Review Article Compilation of Existing Neutron Screen...

Review ArticleCompilation of Existing Neutron Screen Technology

N Chrysanthopoulou12 P Savva1 M Varvayanni1 and N Catsaros1

1 National Centre for Scientific Research ldquoDemokritosrdquo Institute of Nuclear amp Radiological Sciences amp TechnologyEnergy amp Safety 15310 Aghia Paraskevi Greece

2 Department of Physics School of Applied Mathematical and Physical Sciences National Technical University of Athens15780 Zografou Greece

Correspondence should be addressed to N Chrysanthopoulou nefeliiptademokritosgr

Received 17 October 2013 Revised 22 April 2014 Accepted 23 April 2014 Published 11 August 2014

Academic Editor Alejandro Clausse

Copyright copy 2014 N Chrysanthopoulou et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The presence of fast neutron spectra in new reactors is expected to induce a strong impact on the contained materials includingstructural materials nuclear fuels neutron reflecting materials and tritium breeding materials Therefore introduction of thesereactors into operation will require extensive testing of their components which must be performed under neutronic conditionsrepresentative of those expected to prevail inside the reactor cores when in operation Due to limited availability of fast reactorstesting of future reactor materials will mostly take place in water cooled material test reactors (MTRs) by tailoring the neutronspectrum via neutron screens The latter rely on the utilization of materials capable of absorbing neutrons at specific energy Alarge but fragmented experience is available on that topic In this work a comprehensive compilation of the existing neutron screentechnology is attempted focusing on neutron screens developed in order to locally enhance the fast over thermal neutron flux ratioin a reactor core

1 Introduction

A neutron screen is a device a model a system or atechnology that provides the capability of locally tailoring theneutron spectrum It contributes to the creation of desirablespecial irradiation conditions that cannot be achieved duringnormal reactor operation for technological or economicreasons Spectrum tailoring is accomplished by using absorb-ing materialsmdashacting as a filter to neutrons with specificenergiesmdashaffecting thus the flux to which the specimen isexposed In the literature the term ldquoneutron screensrdquo referseither to the absorber or to devices containing a neutronfilter In most of the cases the filter is combined with anothermaterial serving technological physical or chemical reasons

The use of neutron screens technology is imperativewithin the framework of the materials qualification for thedevelopment ofGeneration IV (GEN-IV) reactors since theirperformance can easily and inexpensively simulate the char-acteristics of a fast neutron flux facility and accomplish powertransient experiments Neutronic conditions similar to theones prevailing in fast reactor cores can be achieved inMTRs

by tailoring the neutron spectrum in order to properly tunethe reaction rates For the spectrum tailoring two options areoffered that is either (a) to remove the thermal componentusing a neutron screen technique based for example onCadmium Boron or Hafnium shields or (b) to increase thefastthermal neutrons ratio inside an MTR by using fissilematerial It should be noted that several complexities mainlyof technological nature are involved in the use of thermalneutron absorption shields since all candidate shieldingmaterials have their specific problems induced by weldingbehaviour swelling (eg Boron compounds) ormelting (egCadmium)Therefore research and exchange of informationon neutron screens technology is of increasing interest

The purpose of this report is to present the existingneutron screens technology it is examining the neutronscreens developed to address the lack of fast research reac-tors in sufficient number A neutron screen achieves therequired fast neutron environment by cutting off the thermalcomponent of the neutron spectrum using thermal neutronabsorbing material The absorber is almost transparent tofastmdashand much less to epithermalmdashneutrons In order to

Hindawi Publishing CorporationScience and Technology of Nuclear InstallationsVolume 2014 Article ID 395795 23 pageshttpdxdoiorg1011552014395795

2 Science and Technology of Nuclear Installations

reproduce the irradiation conditions prevailing in a sodium-cooled fast reactor (SFR) environment or in a sodium-cooledfast breeder reactor (SFBR) coolant loops and booster fuelsare combined in the irradiation facility This work furtherinvestigates the power transition facilities that are also basedon neutron screens utilization where also thermal neutronabsorbers are used By varying the absorberrsquos concentrationpower transient on the irradiation sample is achieved Theutilization of variable screens is necessary in order to testthe fuel behavior when exposed to sudden power variationconditions

The report is divided into two sections depending onthe form of the absorbing material used that is solid andfluid neutron screensThe first section is dedicated to neutronscreens which use solid absorbing material and serve forsimulation of fast neutron spectrumconditions In the secondsection neutron screens utilized for power transients arepresented Solid neutron screens can provide larger powertransients than fluid screens since they have higher densitybut their utilization is complex Fluid absorbing materialsare often preferred for this purpose since their screen-ing capability can easily change by varying their pressureandor concentration Several successful examples of neutronscreens performance are reviewed while problems appearingin specific cases are pointed out Computational resultsobtained in order to examine the various neutron screensbehavior using mainly MCNP code [1] are also review-ed

2 Solid Neutron Screens

In this chapter neutron screens which use a solid mate-rial are presented four solid thermal neutrons absorbingmaterials are reported that is cadmium hafnium boronand europium All of them are materials widely used innuclear reactors in several applications and all of them haveadequate thermal neutron absorption cross-sections In eachcase the selection of the appropriate material depends onthe requirements of the experiment the available space forscreen loading the safety issues related to screen loadingand thematerials compatibility Additionally for the materialselection the accumulated experience gained using the spe-cific material for other reactor operations is also exploitedThe factors that should be taken into account in a neutronscreen design are the geometrical configuration of the screenits depletion rate the reactivity effect caused by its insertion inthe core the screen cooling medium the acting field and therequired conditionsThe impact that a neutron screen has onreactor operation (reactivity insertion) and on neighboringexperiments if any should be thoroughly analyzed In thisreport the last issue has not been raised

The solid screens are classified bymaterial and are dividedinto subclasses depending on whether they have already beenused or they are under development or study In cases forwhich neutron screens are under development or study theparameters that should be considered for the safety andeffective neutron screen design are still under investigationand have not accurately been predicted

21 Cadmium Neutron Screens Cadmium is a materialwidely used for thermal neutron filtering because of itsexcellent thermal neutron capture capability Its utilizationin neutron screen technology is very common since thereactors community is familiar with itsmechanical propertiesand other technological issues However cadmium screenconstruction is complex from the engineering point of viewbecause of its low melting point and its large thermalexpansion Because of its extremely high thermal neutroncross-section a slightly thin neutron screen is sufficient totailor the neutron flux distribution in most cases The morethermal neutron-absorbing cadmium isotope is 113Cd whichconstitutes only 12 of the natural cadmium In high neutronfluxes 113Cd is quickly depleted thus demanding frequentreplacement of the screen (or additional material) in orderto avoid unexpected increase of power deposited on theirradiated samples

Cadmium screens are being used for many years nowIn BR2 for instance most of the irradiations from the 1960suntil late 1980s were carried out in the framework of the fastreactor development program andmost of the irradiation rigscontained a cadmium thermal neutron-absorbing screen [2]

211 Cadmium Neutron Screens Already Being Used

(1) BelgianReactor 2 Center forNuclear Energy Research (BR2SCKCEN) In BR2 core (Figure 1) at SCKCEN a Cd screenwas installed around a large Na loop (hosting a single fastreactor fuel pin) which was already surrounded by a gaseous3He screen at variable pressure The experiment named VIC(variable irradiation conditions) was installed in a standard842mm channel of BR2 (Figure 1) and its utilization aimedat liquid-metal fast breeder reactor (LMFBR) fuel pins testingunder transient operating conditions The 3He gas screenserves for fuel power transient while the Cd screen providesa fast spectrum environment by cutting off the thermalneutrons The optimization of the neutronic design of theloop was done by calculating an optimal thickness of thewater annuli between the 3He and Cd screens in order toallow for a certain rethermalization (so that the 3He screenwould be able to induce a transient) keeping at the same timethe thermal component of the neutron flux low enough so asto be a representative of a SFR [3] Utilization of 3He screenfor power transients in VIC is also examined in Section 3

Figure 2 shows the neutron spectra in a BR2 experimentwith (red line) and without (dashed line) Cd screen locatedaxially in a fuel element channelThe installation of the screencuts off the thermal component of the neutron spectrumwhereas it has practically no effect on the high fast flux thusleading the radial fission density distributions across fuel pinbundles and inside the fuel pins themselves to become muchflatter and therefore better simulating the conditions of fastreactor

An additional experiment with cadmium screen namedMOL 7D was installed in the central H1 channel of BR2(Figure 1) in order to study the safety parameters of a SFBRThe MOL 7D loop contained 19 fuel pins in a triangularpitch arrangement of 1 (central) + 6 (inner) + 12 (outer)

Science and Technology of Nuclear Installations 3

Fuel element

Control rod

Reflector

L0P341

P319

K349 K11P19

N330H337 G0 H23

N30

H323 F346

D0

F14

F46

H37

B

A330

C341

A30

C41

C79

C19

E30

C101

C139

C161

F166

K169

K109

L120

G120

K191

L180

G180

D180

B180

P161

P101

P199

D120

F106

A150A210

C190

F194

G60

K49

L60

E330

C319

B300

B240

C221

F314

K311L300

K251P259

L240

D300G300

F254

G240

C281

C259

D240

A270

P41

D60

B60

B120

A90

0

H1

H4 H3

H5 H2

Figure 1 Horizontal cross-section of BR2 with a typical loading [2]

fuel pins and was loaded in the central hole of an Al plugin the central channel of BR2 A Cd screen surrounded theloop (Figure 3) Six fuel elements were loaded into the plugaround the loopThose elements acted as driver fuel elementsboosting the fast and epithermal neutron current entering theloop Concurrently they acted as neutralizers to the strongantireactivity of the neutron absorbing Cd screen [2]

(2) High Flux Reactor (HFR) Petten

(a) TRIO Modified for Irradiation of MOX Fuels (TRIOX)Capsule TRIO is an irradiation device holding three circularcross-section thimbles positioned radially per 120∘ In HFR(Figure 4) a TRIO concept that is TRIOX was utilizedfor MOX fuels irradiation with a Cd screen adapted intothe sample holder carrier for spectrum hardening at thelocation of testing fuel [3] Starting from the center andmoving towards periphery (ie from inside to outside) aTRIOX channel is configured in terms of its radially arrangedmaterials as follows sample (ie fuel pin) sodium (245mm)molybdenum shroud (5mm) sodium (1mm) stainless steel(inner containment 1mm) gas gap (02mm) stainless steel(outer containment 1mm) reactor coolant water (68mm)aluminum (6mm) cadmium (3mm embedded into Alover part of the device height) and aluminum (the capsulematerial) the dimensions in parentheses correspond to

035

030

025

020

015

010

005

000

10Eminus03

10Eminus02

10Eminus01

10E+00

10E+01

10E+02

10E+03

10E+04

10E+05

10E+06

10E+07

Energy (eV)

Flux

per

uni

t let

harg

y

Reflector channelAxis of a SVIG fuel elementInside a Cd-screened device in the axis of a fuel element

Figure 2 Neutron spectra in BR2 [2]

the material thickness The gas gap between primary andsecondary containments consisting of HeNe or NeN helpsto control the fuel pin clad temperature The molybdenumshroud is immersed in the helium pressurized stagnantsodium which fills the primary containment in order toprevent convection currents from appearing in Na when thegap between fuel pin and primary containment is too wide

The cadmium incorporated into the TRIOX capsule actsas a neutron screen for the reduction of the thermal fluxinfluence It is a 05 times 19 mm2 wire which is embedded intothe Al structure in a spiral groove made in the Aluminumtube giving a partial cadmium-cover in the TRIOX holderEffective cadmium cover can be changed depending on thedesign requirements In order to avoid design complicationscadmium screen is not directly incorporated to the sampleholder On the other hand the Cd placement in the coolantwater channel allows for the sufficient cooling required forcadmium but has the drawback that some fast neutrons turnthermal once they have passed the neutron screen whichconstitutes a compromise in the design Moreover all threeTRIOX channels can contain cadmium but this causes asignificant reactivity effect From the HFR operation safetypoint of view the TRIOX capsule should be placed in thelower flux positions since in this way it limits the impact ofcadmium wire on the neutronics of the reactor

(b) High Neutron Fluence Irradiation of Pebble Stacks forFusion (HICU) Project The HICU irradiation project hasbeen implemented inHFR (Figure 4) for Li-ceramics irradia-tion under conditions similar to those of a pebble bed reactor(PBR) Li-ceramics are candidate materials for the breederblanket of fusion reactor HICU combines two neutronscreens hafnium rings have been placed alongwith cadmiumrings creating a neutron screen layer within the sample holdertube The combination of the two absorbers allows for alonger irradiation under fast spectrum conditions


Cadmium screen

SodiumShroud

Fluence monitor position

Figure 3 Horizontal cross-section of the MOL 7D loop with 19 fuel pins in the central 200mm diameter BR2 channel [2]

Figure 5 shows the power density versus time generatedby (119899 120572) reactions on Li

4SiO4(Li ceramics material) in the

dominant spectrum inside the HICU at core position C7for five cases The power generated by both thermal andfast neutrons was calculated using the MCNP code [3] Theabrupt upturn in power generation (curves B C D and E) isdue to the fact that at that moment Cd is completely burntHaving a lower cross-section Hf is expected to cause a moregradual power upturn In fact it can be seen that curve E (amixture of Cd with some Hf) significantly delays the upturnTherefore shield in curve E allows the longest irradiation(over 500 days) in the fast spectrum The behavior of theunshielded (not accounting for burnup) facility (curve A) islinear [3]

In order to study the screenrsquos behavior the neutron fluxinside the HICU was computed with the MCNP code [5](Figure 6) The computations were performed consideringthe HICU loaded at the third highest flux position of HFRcore (C3 or C7 Figure 4) while two types of fusion breedermaterials containing lithium metatitanate that is Li

2TiO3

with natural Lithium (75 6Li) and Lithium-enriched mate-rial (30 6Li) were assumed The screen is based on a 2mmCd shield together with an Hf wire (06 times 06mm2) [5] Theinstallation of HICU in C7 irradiation position (Figure 4)causes a negative reactivity effect of about 1200 pcm (per centmille) which is considered acceptable by the HFR limitingconditions for operation [3] Concerning the utilization ofbreeding materials it is noted that fusion reactions in ITERare fueled by deuterium and tritium the resources of thelatter being extremely limited (currently estimated at 20 kg)Lithium can be used as a solid breeder material of tritiumin the blanket of fusion reactions in ITER while tritium isproduced by the neutrons leaving the plasma and interactingwith lithium in the blanket Li

2TiO3is used as a tritium

breeding material because it allows high tritium release andpresents low activation whilst being chemically stable

212 Cadmium Neutron Screens underInvestigation or Development

(1) Massachusetts Institute of Technology (MIT) In the MITreactor a design for achieving significantly higher neutronflux has been proposed The proposed facility would behosted in the central fast flux trap of theMIT reactor coreThedesign includes a fast flux trap loop surrounded by fissionablematerial (233U 235U 239Pu and 242mAm) reflected and cooledby liquid eutectic Pb-Bi coolant The fissile material could beenriched in either 235U or 233UThe area containing the fissilepins called amplifier ring consists of 164 oxide fuel pinsarranged in four rings of 32 38 44 and 50 pins respectivelyin a hexagonal arrangementThe Pb coolant acts as a ldquodriverrdquoby reflecting fast neutrons and sending them back to thecentral irradiation facility Between the amplifier ring andthe experimental irradiation facility area a Cd filter wasloaded [6] The optimum thickness of Cd was investigatedand the impact of various Cd thicknesses on the neutronflux is summarized in Table 1 An extremely thin layer ofCd (01mm) was found able to reduce the thermal flux wellover 50 while the fast flux decrease was limited to 2 [6]Figure 7 illustrates the impact of the 01mm Cd thickness onthe neutron flux spectrum

(2) Advanced Test Reactor (ATR) Idaho National Laboratory(INL) In the east flux trap (EFT) of the ATR (Figure 8) atINL irradiation tests of high-actinides-content fuels AFChave been performed with the aim to examine the trans-mutation of long-lived isotopes in spent nuclear fuel into


Beryllium

Fuel element

Control element

A B C D E F G H I

1

2

3

4

5

6

7

8

9

5

6

7

8

9

10

PSFW

122E + 14

113E + 14

132E + 14

174E + 14

103E + 14

135E + 14

292E + 14

177E + 14

237E + 14

137E + 14

132E + 14

173E + 14

189E + 14

115E + 14

201E + 14

948E + 14

178E + 14

346E + 13

152E + 14

437E + 13

150E + 14

442E + 13

142E + 14

411E + 13

159E + 14

300E + 13

155E + 14

167E + 13

870E + 13

802E + 13

542E + 13

376E + 13

623E + 13

868E + 13

607E + 13

616E + 13

745E + 13

102E + 14

591E + 13

620E + 13

575E + 13

836E + 13

826E + 13

755E + 13

517E + 13

374E + 13

ΦthermalΦfast

Figure 4 HFR cross-section [4]

shorter lived fission products in an irradiation environmentsimilar to that of a fast reactor The fuels were loaded inan experiment Al-sheathed basket with a 0114 cm thick Cdabsorber filter The device was cooled by light water which isthe primary coolant of the reactor From a study performedwith the combination of MCNP and ORIGEN-2 codes [7] itwas found that at the beginning of irradiation the peak ofthe linear heat generation rate by the metal fuel with andwithout absorber filter was 237 and 2174Wcmminus1 respectively[8] The maximum basket lifetime was estimated to be about48 effective full power days (EFPDs)

Figure 9 compares the neutron flux spectrum in twocases that is the neutron spectrum produced with andwithout Cd filter for the neutron flux spectrum type of aliquid metal fast breeder reactor (LMFBR) [9] The results

show that omission of a Cd filter (Al-basket) results in asofter neutron spectrum [8] and that Cd-filter can adequatelyharden the neutron spectrum in EFT position

22 HafniumNeutron Screens Hafnium is also a widely usedmaterial in nuclear reactors It has excellentmechanical prop-erties it is extremely corrosion-resistant and therefore can beused without doping Another advantage is its high meltingpoint Hafnium thermal neutron cross-section is not as highas that of the other absorbers presented in this chapter How-ever the formation of Hf isotopes under irradiation whichare good thermal neutron absorbers too makes hafniuma good candidate material for neutron screen technologySince it decays to good thermal absorbers its depletionoccurs slowly delaying thus its replacement requirement


150

100

0

0 100 200 300 400 500 600 700 800

Power production in Li4SiO4 20

Pow

er (W

cc)

Irradiation time (days)

ABC

DE

Figure 5 n-120572 power production versus irradiation time calculated for Li4SiO420 enriched in 6Li Notation for curves is as following

unshielded (A) 1mm Cd (B) and 2mm Cd (C) 2mm Cd 400 days at C7 and then at H8 (D) 2mm Cd and 05mm Hf (E) [3]

MTi 75 shieldedMTi 30 shielded

MTi 75MTi 30

1014

1013

1012

1011

Neu

tron

flux

10minus3

10minus2

10minus1

100

101

102

103

104

105

106

107

Energy (eV)

Figure 6 Neutron flux inside the HICU experiment computed forfour conditions with and without neutron screen with natural Li(75 6Li) and with Lithium-enriched material (30 6Li) [5]

in a neutron screen Hafnium is usually combined withaluminum which is a good heat conductor and is transparentto fast neutrons

100E + 14

100E + 13

100E + 12

100E + 11

100E + 10

100E + 09Nor

mal

ized

(to10

MW

) neu

tron

flux

per u

nit l

etha

rgy

100Eminus09

100Eminus08

100Eminus07

100Eminus06

100Eminus05

100Eminus04

100Eminus03

100Eminus02

100Eminus01

100E+00

100E+01

100E+02

Energy (MeV)

No Cd filterWith Cd filter

Figure 7 Effect of a 01mm-thickCd filter on neutron spectrum [6]

221 Hafnium Neutron Screens Already in Operation

(1) HFR Petten A TRIO-facility sample-holder called CON-FIRM has been used for fast reactor fuel irradiation inHFR (Figure 4) In CONFIRM the fuel pin (typical diameter


18

1920

21

2223

24

NW N NE

W

SW S SE

I I I

I

II

I

I

I

I

I

I

IIIII

I

I

I

I

I

I I1

12

73

45

6

23

4

5

6

7

8

9101112

13

14

15

16

17

Small B position

(222 cm)Fuel element

Neck shim rodSmall I position(381 cm)

East flux trap irradiation facilitiesMedium I position (889 cm)

Standard loop irradiation facility

Outer shimcontrol cylinder

Safety rod

OutboardA position(159 cm)

Large Iposition(127 cm)

Large Bposition(381 cm)

Small B 7shuttleposition

H position(159 cm)

Large loopirradiationfacility

Northeast fluxtrap irradiationfacility

diameter)

Berylliumreflector

Neckshim rodhousing

Inboard Aposition(159 cm)

Core reflectortank

(76 cm or 3998400998400 diameter7 positions each 158 cm)

B1

B1

B1

B2

B4

B4B5

B6

B7

B8

B9

B10

(127 cm or 5998400998400

Figure 8 ATR core cross-sectionmdash4 flux traps 5 in-pile tubes and 68 in reflectormdash[10]

Table 1 Effect of Cd filter thickness on the neutron flux [6]

Cd filterthickness (cm)

Neutron flux modification () for four neutronenergy groups

0ndash04 eV 04 eVndash2 keV 3 keVndash1Mev 1ndash10MeV000 0 0 0 0001 minus55 0 minus2 minus2002 minus65 minus1 minus2 minus3005 minus69 minus2 minus2 minus4007 minus71 minus2 minus1 minus4008 minus72 minus5 minus1 minus4013 minus73 minus5 minus2 minus5021 minus73 minus6 minus2 minus8

655mm) is surrounded by a sodium layer (1325mm thick)enclosed in aMo-shroud (24mm thick) for heat conductivitypurposes The material is placed in a stainless steel contain-ment (14mm thick) while a sodium zone (25mm thick)is interposed between the containment and the Mo-shroudA second stainless steel containment (1mm thick) with a05mm Hf shield endues the first containment a 01mm gapexists between the two containments The whole structure is

placed axially in the TRIO wet channel of 315mm diameterconfined by a 1mm thick stainless steel tube [3]

The irradiation holder was fabricated with Hf and wasloaded at the lower flux positions of the coreThe CONFIRMirradiation was carried out in a wet channel of a dry-wet-dry(DWD) TRIO with a standard rig head The outer surface ofHf was cooled by the water flowing of the wet channel Theheight of the shield was larger than that of the fuel providingan effective shielding In order to study the impact of Hfon the power density computations using MCNP [3] wereperformed for variousHf thicknesses (Figure 10) and two fuelpins of plutoniumwith 87 Pu-239 As can be seen changingof the shield thickness has a large impact on the powerdensity The spectrum in the molybdenum shroud whichsurrounded the fuel sample was also computed Figure 11shows the impact of a 4mmHf shield on the spectrum whileFigure 12 shows the thermal energy range in detail for five Hfthicknesses Figure 13 shows the variation of the normalizedpower as well as of the normalized flux per unit lethargy as afunction of the Hf thickness the variations are very similar

(2)High Flux IsotopeReactor (HFIR)OakRidgeNational Lab-oratory (ORNL) In HFIR ORNL (Figure 14) an irradiationfacility that allows testing of advanced nuclear fuels underprototype LWR (Light Water Reactors) operating conditionsin approximately half the time it takes in other research


10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus10

10Eminus8

10Eminus6

10Eminus4

10Eminus2

10E+0

10E+2

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)

Cd-filterAl-basketLMFBR

Figure 9 Comparison of fast-fission spectrum (LMFBR) with theneutron spectrum produced with and without Cd [9]

1600

1400

1200

1000

800

400

600

200

00 2 4 6 8 10 12 14 16

Top upper Bottom lower

Pow

er (W

cm

3)

Axial position

1mm steel1mm Hafnium2mm Hafnium

3mm Hafnium4mm Hafnium

Figure 10 The influence of the thickness of the Hf shield on thepower density in the two fuel pins [3]

reactors has been developed The cylindrical irradiationdevice holds three axial thimbles of circular cross-sectionwith their centers located radially per 120∘ forming aninscribed concentric circle The intermediate space aroundirradiation holes is filled with aluminum and each capsule issurrounded by a coolant channel Three flux monitor tubes

35E + 14

30E + 14

25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

1E

minus09

1E

minus07

1E

minus05

1E

minus03

1E

minus01

1E

+01

1E

+03

Energy (MeV)0mm Hf4mm Hf

Figure 11 The spectrum in the molybdenum shroud surroundingthe fuel [3]

25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

0mm Hf1mm Hf2mm Hf

3mm Hf4mm Hf

1E minus 08 1E minus 07 1E minus 06

Energy (MeV)

Figure 12 The spectrum in the molybdenum shroud surroundingthe fuel Detail of the thermal energy range for five Hf thicknessesThe horizontal lines mark the height of the thermal peak [3]

also surrounded by coolant are placed radially each onebetween two successive irradiation holes The goal of thisdesign is to maintain a relatively constant linear heat rate AnHf screen surrounds the facility basket which is located in thereflector region of HFIR

Two LWR experiments have taken place using the aboveirradiation facility the first contained UN (uranium nitride)and the second contained UO

2fuel pellets inside SiC

claddingThe facilities contain nine fuel pinsmdasheach compris-ing 10 fuel pelletsmdasharranged as three fuel rods (Figure 15) [11]Design calculations indicate that a 161mm thick Hf shielddegrades at a rate similar to the burnup of 38-enrichedUO2fuel so that the linear heat generation rate of the fuel

remains relatively constant at least over the first few cyclesWith this configuration and shield thickness linear power


120

100

80

60

40

20

0

120

100

80

60

40

20

00 1 2 3 4

Nor

mal

ized

pow

er (

)

Hafnium thickness (mm)

Flux

leth

argy

at th

erm

al p

eak

()

Total power (W)Normalized fluxlethargy

Data are normalized tothe 1mm steel (0mmhafnium situation) whichis put at 100

Figure 13 The normalized power density and the normalized fluxper unit lethargy at the thermal peak plotted as a function of the Hfthickness [3]

ratings average 22 kWm for the upper and lower capsulesand 32 kWm in the medium capsule Eventually the screenwas fabricated with a thickness of 0272 cm [18]

222 Hafnium Neutron Screens underDevelopment or Investigation

(1) ATR INL Regarding the development of irradiationcapabilities under fast neutron spectrum conditions at ATR(Figure 9) a boosted fast flux loop (BFFL) concept (Figure 16)has been proposed The desired fast to thermal neutron fluxratio is over 15 The BFFL was designed to be hosted in agas test loop (GTL) in one of ATR corner lobes that isNW or NE (Figure 9) where large space is available In theframework of the GTL Project Conceptual Design severalconfigurations of an experiment facility that could replicatea fast flux test environment have been studied The BFFLcombines boosters for neutron flux enhancing and thermalneutron absorber for neutron filtering and for reinforcing theincrease of fast to thermal flux ratio The absorbing materialis a Hf-Al composite This material retains the high thermalconductivity of Al and has the thermal neutron absorptionproperties of Hf With this approach the produced heat canbe removed by conduction and can be transferred from theexperiment to pressurized water cooling channels [13 19]The fuel meat in the booster fuel is Si meat enriched to 93(U3Si2) in 235U In U-Si plates of the required fuel loading

meat thickness and curvature are prototypes [13] The designshown in Figure 16 provided a fast flux of approximately105 times 1015 ncm2s and a fast (gt01MeV) to thermal (herelt0625 eV) neutron flux ratio of about 23 averaged over16 cm in the three tubes (test spaces) [12] The coolants ofthe configuration include ATR primary light water coolantHe and Na Helium being inert single phase and withoutreactivity effects it was chosen as the gas coolant mediumIn order to study the impact of Hf concentration on thefastthermal neutron flux ratio MCNP calculations wereperformed (Figures 17 and 18) [14] The greater the presenceof Hf in Al the greater the removed fraction of thermal

neutrons (Figure 17) would be The heating rates in the Hf-Al as a function of the Hf concentration in the absorber areshown in Figure 18 The heating rate appears to saturate atabout 6 to 7 Hf concentration which suggests that thispercentage may correspond to an optimum Hf loading [14]It was indicated that with a 65 or greater concentration inHf a fast to thermal neutron flux ratio greater than 40 can beproduced [18]

(2) OSIRIS Saclay An Hf neutron screen has been installedbetween OSIRIS reactor core (Figure 19) and ISABELLE testrig ISABELLE 4 loop has been designed for the irradiationof fuel elements under conditions representative of those ofa pressurized water reactor (PWR) and power transient irra-diation The loop can house 1ndash4 fuel elements or absorbentelements and can be inserted and removed while the reactoris operating The power that can be evacuated by the loop is90 kW and the maximum linear power on the fuel elementsis 500Wsdotcmminus1 The aim of the screen was a higher than01MW fast neutron flux (21013 ncm2sdots) to be reached inthe test rig through the thermal component cutoff by HfThe2mm thick screen is surrounded by a block of 10mm thickAl and is cooled by forced convection from two water gapsThe Al block consists of 3 removable plates with 3mm watergaps in-between that provide cooling by natural convectionHf depletion is low making its replacement during theirradiation unnecessary

23 Boron Neutron Screens Boron and its compounds findextensive application in nuclear reactors Natural boronconsists of 20 10B and 80 11BThe extremely high thermalcross-section of 10B together with its low abundance causequick depletion of the boron screen The depletion can bedelayed by 10B enrichment In contrast with other absorbersthat is cadmium Boron has a significant neutron absorptionin the epithermal energy range Boron is usually combinedas a carbide or oxide However an Al-B alloy has beensuccessfully used as neutron screen and another is underdevelopment A factor that should be taken into account ina boron neutron screen design is the swelling that can becaused due to helium generation after boron irradiation withfast neutrons

231 Boron Neutron Screens Already in Operation

(1) ATR INL In order to achieve a high fast (gt01MeV) tothermal (here lt01 eV) neutron flux ratio [16] a 025 cm thickneutron screen of Al-B alloy filter has been inserted in theirradiation test vehicle (ITV Figure 20) in ATR (Figure 8)The ITV is loaded in the central flux trap where the highestneutron flux occurs The inert inner region of the ITVis filled with Al (Figure 20) in order to avoid water thatwould increase neutrons thermalization He or N

2gases have

been selected for the specimens cooling The screen shouldbe replaced after a certain irradiation time In Table 2 theneutron flux values for a case with the Al-B alloy filter (43wt of 10B in Al) and a case without the Al-B alloy filter arepresented As can be seen the presence of the Al-B screenincreases the fast over thermal flux ratio about twice


Target bundle

Horizontal

Peripheral target

in flux trap

beam tube

position

Inner fuel elementOuter fuel element

Control region

Large vertical

facility (VXF)experiment

Small vertical


Large removable

(RBlowast) beryllium facility

HB-1

HB-2

HB-3

HB-4

0 2 4 6

(Inches)

Figure 14 HFIR horizontal cross-section [11]

Basket assembly

Capsuleassembly

Stainless steel containment

SiC fuel pin assembly

UN or UO2 fuel pellets

Figure 15 Vertical view of the thermal neutron irradiation facilitywith a close-up of one of the nine capsule assemblies [11]

232 Boron Neutron Screens under Development or Study

(1) ATR INLAnAl-B screen has been proposed to be loadedin a test facility in the ATR (Figure 8) in order to harden thespectrum providing an acceptable environment for V alloytesting (The two basic design goals of the test design assemblywere the achievement of 10 displacements per atom (dpa) peryear in vanadiumwhile limiting the 51V transmutation to lessthan 05 for a 30 dpa experiment) The ITV is installed in

Table 2 Neutron fluxes for ATR ITV midplane specimens [16]

Neutron flux at 26MW Center lobe power(ncm2sdots)

Filtered UnfilteredThermal(here lt01 eV) 113 sdot 1014 176 sdot 1014

Fast(gt01MeV) 455 sdot 1014 454 sdot 1014

FT 403 258

the central flux trap where the highest value of the neutronflux occurs The fast (gt01MeV) to thermal (here lt0415 eV)[20] neutron flux ratios for a 254 cm Al-B screen (with95 10B enrichment) have been calculated with MCNP andORIGEN-2 codes [21]The results are presented in Table 3 Ascan be seen the fast over thermal flux ratio (FT) decreaseslinearly over operation time because of the 10B depletion inthe Al-B alloy

Figure 21 shows the impact of an Al-B filter installationon the neutron As the enrichment increases the hardeningof the neutron spectrum is more intense Three differentcases are depicted (a) without filter (b) with Al-B (10B 60enrichment) filter and (c) with Al-B (10B 95 enrichment)filter The FT ratios for the unfiltered case have beenestimated to reach146 whereas with the highly enriched Al-B filter (10B 95) the FT ratio in BOL (beginning of life)reaches 1425 (Table 3) In order to hold the averaged ratioover 80 the filter needs to be replaced after 160 EFPDs (4


125998400998400 OD 125998400998400 ID

10998400998400 OD test space

Al-6061 spacerassembly

025998400998400 ID coolant hole


46 PCS water channels6061 aluminum end plate

6061 aluminum clad

Aluminum baffleStainless steel pressure tube (IPT)

Stainless steel envelope tube

Al-6061 support tubefor the Hf filter

U3Si2 fuel (1228 kg Uper quarter assembly)

North

Dimensions in inches

Gas gap 004998400998400 thick

(He sim30 psig)

Hegas

Hf filter (0040998400998400 or sim1mm)

Water (0078998400998400 or sim2mm)

Figure 16 A graphical representation of the Gas Test Loop conceptual design [12]

60

50

40

30

20

10

00 2 4 6 8 10 12

1055

1050

1045

1040

1035

1030

1025

Fast

to th

erm

al ra

tio

Fast

flux

(1015

ncm

2s

)

Hafnium ()

Figure 17 Sensitivity of fast-to-thermal ratio (blue line) and fastflux intensity (magenta line) to the Hf content in the Al central fillerpiece (absorber) The cycles on the graph correspond to the fast fluxmeasurements [13]

60

50

40

30

20

10

00 2 4 6 8 10 12

16

14

12

10

8

6

4

2

0

Hea

t den

sity

(Wc

m3)

Hea

t rat

e (W

g)

Hafnium ()

Figure 18 The heating rate (magenta line) and heat density (blueline) of the Hf-Al averaged over the central 40 cm (16 inches) of thecore height [14]

Table 3 Fast (gt01MeV) to thermal (here lt0415 eV) neutron fluxratios versus irradiation EFPDs at ITV [21]

Irradiation days Neutron flux FT ratioBoL 14251EFDPs 20 13048EFDPs 40 12721EFDPs 60 12025EFDPs 80 11384EFDPs 100 10854EFDPs 120 9924EFDPs 140 9178EFDPs 160 8799

typical operation cycles)TheAl-B (10B 95) screen canmeetthe desirable requirements [21]

(2) Budapest Research Reactor (BRR) In the frame of theMTR+I3 project a parametric neutron screen studywasmadefor the largest irradiation channel of the BRR (Figure 22)TheB4C filter was inserted between the walls of an Al irradiation

tube The area outside the irradiation tube was surroundedby Al displacers The dimensions of the irradiation tube areshown in Table 4 Two changing parameters were investi-gated that is the thickness of the filter and the enrichment of10B In total eight cases were studied and compared with thereference case in which the B

4C filter was replaced by AlThe

energy spectrum was divided in five groups with their upperboundaries given in Table 5 The influence of the thicknessand enrichment variations on the energy spectrum and on


Ecran EcranEcranEcran

NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a

Figure 19 Horizontal cross-section of OSIRIS core [15]

Table 4 Dimensions of the irradiation tube [17]

Component (mm)Irradiation tube inner radius 28Irradiation tube inner wall thickness 2Neutron filter thickness maximum 7Irradiation tube outer wall thickness 3mm 3Irradiation tube outer radius 40mm 40

Table 5 BRR energy spectrum boundaries [17]

Group number Upper boundary (MeV)1 000012 013 054 105 200

neutron flux is shown in Figures 23 and 24 respectively Thefollowing results were derived by this study

(i) The maximum 10B density causes the maximumtailoring in the spectrum

(ii) All filtering configurations in the thermal energygroup have as a result an effective reduction of thethermal part of the spectrum

(iii) For groups 3 and 4 the filtering effect is very similar

(iv) The same filtering of the spectrum can be obtainedwith different filtering configurations (eg differentenrichment in 10B or different filter thickness)

(v) In filtering cases the thermal neutron fluxes havethe smallest value in contrast with the reference casewhere the opposite occurs

(vi) The presence of B4C causes an increase of 1100ndash

1400 pcm on the reactivity which is not acceptable inreference to the limiting conditions for operation ofthe reactor

Although the results of the study have shown the great ther-mal neutron absorption capability of B

4C its utilization was

not considered in practice because of its reactivity effect and


All dimensions in cm

Upper specimen capsules(189 OD times 173 ID)

Water coolant gaps

Pressure tube (311 OD)

Temperature control gas gaps

Lower specimen capsule (251 OD times 224 ID)

Neutron filter (798 OD times 747 ID)

Thermocouples (016 OD)

411 BC

Center flux trap (815 inside DIA)

Gas channel tube

(256 ID)

Thermocouple sleeve(251 OD 189 ID)

Aluminum filler(726 OD IPT holes ARE 333 ID)

Figure 20 Core region ITV cross-section without specimens [16]

its low heat conductivity [17] The Budapest Advanced Gas-cooled Irradiation Rig Assembly (BAGIRA) rig is recentlyredesigned with B

4C shield [22]

24 Europium Neutron Screens Europium is a material withextremely high thermal neutron cross-section The use ofeuropium is limited since it is rare and hence expensive Innuclear reactors europium is utilized in control rods In thissection only one neutron screen with europium is presentedthat is currently under development in HFIR The FT fluxratio that is predicted to be achieved with europium screen isremarkable (gt400)

241 Europium Neutron Screens Already in Operation Casesof europium neutron screens already used in reactor facilitieshave not been found in the open literature possibly due to thereasons described above

242 Europium Neutron Screens underDevelopment or Investigation

(1) HFIR ORNL An analysis of a fast spectrum irradiationfacility design has been performed in HFIR (Figure 14) at

ORNL The screen has been planned to be installed at thereactor flux trap (FT) (southeastern core part) where the fastneutron flux exceeds 11015 ncm2sdots and the thermal neutronflux may exceed 251015 ncm2sdots [23] A tri-pin assemblydesign (Figure 25) occupying seven target locations wasselected for the application

Calculations of performance characteristics such as linearheat generation rate neutron fluxmagnitude fast-to-thermalflux ratio and displacements per atom (dpa) were performedin HFIR using the MCNP code [24] The results are providedin Table 6 From the obtained results it appears that theproposed requirements of fast neutron flux greater than 1 times1015 ncm2sdots and fast-to-thermal flux ratio greater than 300are achieved It was concluded that this design could providea fast (gt01MeV) to thermal (here lt0625 eV) neutron fluxratio over 400 Figure 26 presents a comparison between theexisting neutron spectrum in the FT and the spectrum insidea 3mm thick europium shieldThe insertion of the screen hasan acceptable impact on the power distribution (less than 9as required by the HFIR safety analysis [25])

25 Summarized Results on Solid Neutron Screens Neutronscreen performances can easily and inexpensively meet


Table 6 HFIR irradiation parameters for proposed tripin concept [23]

Parameter ValueFast (gt01MeV) neutron flux in irradiation volume 12 sdot 1015 ncm2

sdotsec(a) Annual3 fast (gt01MeV) neutron fluence at peak irradiation position 16 sdot 1022 ncm2

(b) Burnupyear 59(c) dpa 195Fuel burnup-to-clad dpa ratio at peak irradiation position 03 atoms per dpaFast (gt01MeV) to thermal (here lt0625 eV) flux ratio 400He-to-dpa ratio in iron at peak irradiation position 02 appm He per dpaLinear heat rate (variable depending upon design of Eu2O3 shield) 300Wcm3Annual estimates are conservatively based on seven cycles per year

10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)

UnfilteredWith AI-B (10B 60 enriched)With AI-B (10B 95 enriched)

Figure 21Neutron spectrumcomparison for three cases unfilteredwith Al-B (10B 60 enrichment) filter and with Al-B (10B 95enrichment) filter [8]

demands for a fast neutron flux facility which arise dueto the absence of adequate number of fast experimentalreactors In Section 2 neutron screens which use a solidshielding material were presented The screens that werereported are either already successfully implemented andused or are still under development or study The purpose oftheir use is the creation of an environment with a neutronenergy spectrum free as much as possible from thermal andepithermal neutrons

Four solid materials were presented that is boroncadmium hafnium and europium In principle the materialselection depends on the reactor which will host the screenand on the required conditions that should be achievedEuropium has not met great industrial development due to

VacuumBe reflector

Be displacers

Water

Figure 22 The geometry of the B shield (marked by the red arrow)inside BRR [5]

its excessively high cost compared to boron cadmium andhafnium which are widespread in nuclear reactors From thesafety point of view europium oxide reacts readily with waterand boron gets highly corrosive at high temperatures On thecontrary hafnium and cadmium are both corrosion-resistantmetals Regarding their mechanical properties cadmium hasthe disadvantages of low melting and low boiling pointsIrradiating boronwith fast neutrons induces the generation ofhelium causing swelling Hafnium exhibits the best mechan-ical properties

The size of the screen depends on the materials depletionand on the experiment requirements The fact that europiumand hafnium activation products have high-cross sectionsdelays their depletion with time extending thus the neutronscreen operational time On the contrary boron and cad-mium have only one isotope with high cross-section and inlow abundance so that both deplete fast with time There-fore boron and cadmium neutron screens demand frequentreplacement in order to prevent a sudden upturn on the reac-torrsquos power deposited on the irradiated sample Furthermorein order to compensate the fast depletion increment of theabsorberrsquos content in the screen is sought This is achieved


050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)

Reference case (no filtering)d = 3mm 10B enr natd = 3mm 10B enr 90d = 5mm 10B enr natd = 5mm 10B enr 90d = 7mm 10B enr natd = 7mm 10B enr 90d = 7mm 10B enr nat + B4C displacerd = 7mm 10B enr 90 + B4C displacer

Figure 23The spectrum in thewhole volume of the irradiation tubefor each case [17]

either by increasing the volume of the material or throughenrichment of the absorber (ie 10B enrichment) the cost ofthe screen being increased accordingly On the other handhafnium has the lowest cross-section of all four materialsTherefore in order to fulfill the same requirements largervolume of hafnium must be used compared to the necessaryvolumes of other screening materials In general few mm ofabsorber thickness are sufficient

Fromall of the fourmaterials boronhas the highest cross-section in the epithermal energy region and its behavior isregular Europium and its isotopes have also very importantcross-section in that region (order of 104 barns) but incontrast with boron they present many resonances Hafniumand its isotopes also present high neutron capture in theepithermal region with many resonances (order of 103ndash105 barns) Finally cadmium has the lowest epithermal cross-sections (order of 103-104 barns) The epithermal neutroncapture capability of the absorbers results to a neutronspectrum which better represents that of a fast reactor Acombination of absorbers can be utilized in order to createa more efficient neutron screen

3 Fluid Neutron Screens

In this chapter neutron screens which use a gaseous or aliquid thermal neutrons absorbing material are presentedThe purpose of fluid screens is to generate power transientsthat is power increase or decrease in a few seconds on thevolume of a fuel sample Fuels fission power alteration is

1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)


Figure 24 The multigroup fluxmdashcorresponding to the 10MWthermal power of the BRRmdashin the whole volume of the irradiationtube for each case [5]

achieved through the fluctuation of the absorbent content inthe screen (thickness of the screen or absorberrsquos enrichment)The fluctuation is accomplished by pressure variation (ie3He case) or variation of the concentration of the absorber(ie 10B in boron compounds) in the screen surrounding thefuelTheperformance of variable screens is necessary in orderto examine the fuels behavior in case of exposure to suddenpower variation conditions

Three different types of variable neutron screens arereported in this chapter that is gaseous 3He liquid H

3BO3

and gaseous BF3 Gaseous BF

3and 3He screens performance

has been abandoned in most of the reactors since both gasespresent characteristics that can jeopardize reactorrsquos safety3He screens have been replaced by liquid H

3BO3ones

Parameters that can enhance the transient amplitudecomprise the core location where the screen is adapted thedistance between the screen and the sample the absorber typethat is used in the screen the absorber content in the screenand the operational phase of the reactor In addition largeamplitude transients can be achieved by combining the screenmodification and the reactor power changes for examplescram

The fluid screens are classified bymaterial and are dividedinto subclasses depending on whether they have already beenused or they are under development or study

31 Helium-3 Neutron Screens 3He is a gaseous syntheticisotope of natural helium and is often used in nuclear


Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel

Figure 25 Tri-pin fast flux shielded irradiation design at HFIR (ORNL) [25]

14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)

1E minus 09 1E minus 07 1E minus 05 1E minus 03 1E minus 01 1E + 01

Neutron energy (MeV)

Fuel pin with Eu2O3 shieldReference HFIR spectrum

Figure 26 Neutron flux spectra within the FT region of HFIR andthe tri-pin fast irradiation facility [23]

reactors 3He thermal neutron cross-section is extremelyhigh making this material an excellent absorber Most ofpower transients with a 3He neutron screen have nowadaysbeen abandoned for safety reasons aroused due to productionof Tritium with 3He activation The first experiment with avariable 3He neutron screen was made in 1977

311 Helium-3 Neutron Screens Already Operational

(1) BR2 SCKCEN

(a) Pressurized Water CapsuleCycling and Calibration Device(PWCCCD) In BR2 at SCKCEN a pressurized water cap-sulecycling and calibration device (PWCCCD) (Figure 27)device has been used for fast power transients on fuel pinsunder conditions similar to those of a boiling water reactor(BWR) or a PWR This is accomplished through 3He pres-surizationdepressurization (1ndash38 bars) With a 2mm widegas gap a transient factor of 175 has been achieved ThePWCCCD device has been applied in several fuel rampingtests during the last 30 years

(b) VIC Experiment A variable pressure 3He screen has beenutilized in BR2 for fuel power transient in VIC experiment(Figure 2) The screen surrounded a Na gas loop in whichthe sample was inserted (Figure 28) The use of 3He screenprovided transient amplitude of 80 As it has been stated inSection 2 the VIC experiment also consisted of a Cd screenwhose presence reduces the transient amplitude to 25 [3]

(2) Halden Norway Although the He gaseous screen per-formance in most reactors has been abandoned ramp testfacilities with 3He screen are still in operation in the Haldenreactor More precisely in-pile loops with gaseous 3Heare utilized for studying the fuel rods performance underpower transient conditions The experiment is surroundedby Zircaloy in order to be isolated from the reactor environ-ment The pressure variance of the gaseous 3He can providea ramping factor up to 4 and a ramp rate between 100 and


Inlet temperaturemeasurement

He screen

Fuel segment

Centre grid PWC module

Al plug

Water flow direction

Outlet temperaturemeasurement

Flow measurement

Stagnant water screen

PWC module with fuelsegment

CCD module

Figure 27 Exploded 3D view of the PWCCCD assembly [26]

200Wcmmin Several power test series have been executedfor the investigation of fuelsrsquo behavior during normaloffnormal operational transients [20] In Figure 29 four typicalpower ramp tests are shown

32 Boron Neutron Screens Boron isotope 10B has anextremely high thermal cross-section For power transientexperiments boron compounds are used 10B enrichmentcan be utilized in order to increase the power transient Asstated in Section 23 boron utilization should seriously beconsidered due to its high reactivity effect Two types of boronfluid screens are described gaseous BF

3and liquid H

3BO3

BF3utilization has been abandoned due to its corrosive and

poisonous nature and its relatively low absorption cross-section which requires screen utilization at high pressure

321 Boron Neutron Screens Already Operational

(1) HFR Petten

(a) MOKA-POTRA-BISAR Experiments A BF3gas screen

has been used in the MOKA POTRA and BISAR boilingwater fuel capsules in HFR (Figure 4) for power control infuel irradiation experiments The capsule carrier is placed in

an aluminum filled space and its horizontal cross-section isdescribed by nine concentric rings surrounding the 104mmradius fuel rod The ringsrsquo compositions and widths in mmfrom center to periphery are respectively Zirconium 134water coolant 146 aluminum 9 water coolant 2 aluminum11 stainless steel 6 BF

3 135 stainless steel 6 water coolant

15 The high thermal neutron absorption of 10B can causea power reduction although the BF

3gas was not sufficient

for large power ramps in the in-pile experiments performedStainless steel was used as a construction material and BF

3

gas was inserted into a special annular space surrounding thefuelThe typical pressure of the gas screen was 50 bar causing20 power reduction Due to the low cost of enriched B thepossibility of using enriched BF

3mdashinstead of naturalmdashwas

consideredWith the same amount of enriched BF3less space

would be necessary and more neutron absorption could beachieved without pressure changes Moreover safety wouldalso be increased BF

3is no longer in use at the HFR because

of its corrosiveness poisonous nature and its relatively lowabsorption cross section which requires screen utilization athigh pressure

(b) TOP Experiment BF3gas screen has been used in a

TOP-scenario experiment in order to study the influence of


VICloop

Double wrapper tube (He inside)

Na containment tube

Enveloping tube (OD 445mm)

Upward Na circulation

3He screen (35mm) 1 to 38 bars

BR2 cooling water

Protecting tube

Cadmium screen (25mm)

Cooling sleeve

Downward Na circulation

Fuel pin (empty6 or 76mm)

BR2 channel empty842mm (Be)

Figure 28 VIC loop cross-section [3]

Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time

Off-normal transient

125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

Figure 29 Four typical power ramp tests at Halden [20]

fast reactor fuelrsquos structure under overpower conditions Thefacility was placed outside the core in the pool side facility(PSF) The sodium-cooled fast reactor fuel was irradiatedwith 1800Wcm maximum The region around the sodiumcontainment was filled with BF

3gas acting as neutron shield

The variation of BF3concentration the displacement of the

facility (to and from the core) or the combination of bothallowed a power transient factor of 2 to 4 The maximumpressure of BF

3into the irradiation device was 45 bar B

pressure increase varied slightly the power reduction andneutron absorption


(1) BR2 SCKGEN A water screen with a variable con-centration of H

3BO3was developed at SCKCEN for fuel

power transient experiments (Figure 30) The screen calledVANESSA surrounds a ldquoclassicrdquo pressurized water capsule


BR2 84mm channelAl filler tube

Outer tubeOuter screen

Separation tubeInner screen

Inner screen tubeGas gap

Inner tube

PWC

BR2 water channel thicknessPressure tube thicknessIsolation gap thicknessScreen inner tube thicknessInner screen thicknessSeparation tube thicknessOuter screen thicknessScreen outer tube thickness

3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter

Aluminium tubeHe isolation gapAluminium tubeInner screenAluminium tubeOuter screenAluminium tube

mmmmmmmmmmmmmm

34ndash3838ndash4242ndash4646ndash5252ndash5656ndash6262ndash66

Figure 30 Horizontal cross-section of VANESSA with dimensions[28]

(PWC) in BR2 reactor (Figure 1) and was developed inorder to replace the existing screen based on 3He pres-surizationdepressurization [27] The modification of boronconcentration allows the tuning of the basic linear powerTheH3BO3concentration can vary between zero (ie pure water)

and slightly below the saturation value of about 60 g H3BO3

per liter at room temperature VANESSA screen was loadedin a BR2 high flux channel for transient testing on very highburnup fuel VANESSA not only provides the variable ther-mal neutron absorption but via the thermal balance methodalso serves for fuel rod power determination Through thevolume of H

3BO3solution generated during the operation

limited number of transients during a cycle takes placeVarious contentenrichments of 10B have been studied

The results showed that with natural boron a fuel powertransient factor of about 20 could be achieved while with100 enriched 10B the power transient factorwas increased to45 [27]The ramp factor has been calculated for two differentscreen thicknesses that is (a) 2mm ramp factor 2 (almostlinear dependence on B concentration) and (b) 65mm rampfactor 4 (strongly nonlinear) [28] A study of the thermalbehavior of the VANESSA part showed thatH

3BO3should be

continuously refreshed (at least every 3 s) in order to avoid itsstagnancy that could lead to unacceptably high temperaturesThe cooling of the screen is performed by the primaryBR2 cooling system water VANESSA can also be used incombinationwith RODEO (rotatable device for the executionof operational transients) device (Figure 31) The RODEOconcept is a rotating plug inserted in the peripheral 200mmdiameter channel of BR2 The PWC is inserted commonlyin an eccentric 84mm channel within RODEO and can berotated by 180∘ Three solutions for the plug material werestudied RODEO filled with water gives the highest transientratio [27] The results are shown in the Table 7

The power increase in the H3 and H4 channels (Figure 1)was calculated With zero H

3BO3

concentration inVANESSA the power in these channels increases by 0to 4 by RODEO rotation (from the remote position to thenear position) With saturated natural boron H

3BO3 the

rotation has a result of 1 to 5 decrease For intermediate Bconcentrations the influence of the RODEO rotation on theneighboring fuel elements will therefore be extremely smallRODEO rotation can be achieved on a time scale of the orderof a few seconds This leads to the conclusion that very fastpower transients with RODEO are possible [27] Figure 32shows the combined utilization of VANESSA and RODEO

33 Summarized Results on Fluid Neutron Screens InSection 3 neutron screens which use a gaseous or a liquidthermal absorbing material were presented The purpose offluid screens is to generate power transients in order toexamine fuelrsquos behavior in case of exposure to sudden powervariation conditions

Two different materials are typically utilized helium andboron that is gaseous 3He gaseous BF

3 and liquid H

3BO3

BF3and H

3BO3screens were developed with the purpose

to replace the widely used 3He screen for safety reasonsHowever BF

3performance also causes safety concerns

through neutron capture 3He generates tritium and BF3

can potentially form F2which is a poisonous and corrosive

gas Compared to the previous materials H3BO3can be

considered a safe candidate for performing power transientssince it is not corrosive and does not produce active by-products3He has an extremely high neutron absorption cross-

section For this reason its replacement with boron com-pounds having much lower cross-sections cannot providethe same power transients This can be compensated eitherby pressure increment or by boron enrichment Moreoverthe screen can be combined with a displacement system(RODEO)

Fluid neutron screens can provide successful powertransients In cases requiring higher power deviations thescreens can be combined with reactorrsquos power alterations orwith displacement systems

4 Overall Conclusions

Neutron screen technology has been developed in order tofulfill several application requirements The key idea of theneutron screens is the utilization of somematerials capabilityto absorb neutrons at specific energy range In this report onlyscreens which utilize thermal (and epithermal) absorberswere presented

First the capability to simulate fast nuclear reactorconditions in a specific area by adapting a neutron screenis reviewed through the presentation of relevant studies andapplications As arises from the available literature severalneutron spectra have been simulated in different reactorsFour solidmaterials were presented that is boron cadmiumhafnium and europium Their performance characteristicsdiffer in terms of their mechanical properties compatibility


IPS penetration

Worm gear

Skirt

Upper flangeUpper thrust bearingRotating plug support

Rotating plugLower thrust bearing

Needles bearing

200mm channelguide tube

Be plug support tube


VANESSA outer tube

Figure 31 RODEO rotating plug at BR2 [27]

depletion and so forth However in most cases presented inthis chapter the utilized material could be replaced by one ofthe rest The material selection is determined by factors suchas the reactor conditions desired to be simulated the reactortype in which the screen will be inserted (and its operationalconditions) the reactor coolant (in order to prevent safetyissues arising from possible interactionwith coolant) and theavailable space for the screen

Second the capability of the existing reactors to irradiatesamples under power transients by exploiting the perfor-mance of neutron screens is examined based on reportedexperience More specifically the utilization of neutronscreens with fluid materials is reviewedThe method is based

on the gas pressure or the liquid concentration variationso that power transients can be initiated Two differentmaterials have been reported that is helium and boronnamely gaseous 3He gaseous BF

3 and H

3BO3 The last two

neutron screens have been developed in order to replace theunsafe utilization of 3He because of the tritium generationproblem BF

3utilization has been limited and eventually

abandoned because of its corrosive and poisonous natureMoreover its performance could not reach power transientranges equivalent to those obtained using 3He Likewise byusing H

3BO3the achieved power transients appear much

lower so that the screen is combined with a displacementsystem (RODEO) thus providing very fast power transients


Table 7 Three solutions for the plug material have been evaluated beryllium light water and aluminum [27]

Min linear power (kWcm) Max linear power (kWcm) RODEO transient ratioBe

Without H3BO3 123 245 2063 gL H3natBO3 061 121 2063 gL H310BO3 020 044 22

H2OWithout H3BO3 039 187 4863 gL H3natBO3 0165 067 4163 gL H310BO3 0055 024 44

AlWithout H3BO3 120 152 1363 gL H3natBO3 069 092 1363 gL H310BO3 031 042 13

Figure 32 RODEO and VANESSA cross-section [29]

The main conclusion is that neutron screens are worthstudying and developing since they can successfully con-tribute to the creation of desirable special irradiation con-ditions which cannot be achieved during normal reactoroperation due to technological or economic reasons

Abbreviations

AFC Advanced Fuel Cycleappm Atomic parts per millionATR Advanced Test ReactorBAGIRA Budapest Advanced Gas-cooled

Irradiation Rig AssemblyBFFL Boosted Fast Flux LoopBOI Beginning Of IrradiationBOL Beginning Of LifeBR2 Belgian Reactor 2

BRR Budapest Research ReactorBWR Boiling Water ReactorCCD Cycling and Calibration DeviceCONFIRM Collaboration On Nitride Fuel Irradiation

and Modelingdpa Displacements per atomDWD Dry-wet-dryEFDPs Effective full power daysEFT East flux trapESF European Social FundFT Fast to thermalFR Fast reactorFT Flux trapGEN-IV Generation IV (GEN-IV)GTL Gas test loopGTL Gas test loopHFIR High flux isotope reactorHFR High flux reactorHICU High neutron fluence irradiation of pebble

stacks for fusionINL Idaho National LaboratoryITV Irradiation test vehicleLHGR Linear heat generation rateLMFBR Liquid metal fast breeder reactorLWR Light water reactorLWR Light water reactorsMCNP Monte Carlo neutron particleMCWO MCNP with origen 2MIT Massachusetts Institute of TechnologyMOX Mixed oxideNSRF National Strategic Reference FrameworkORNL Oak Ridge National LaboratoryPBR Pebble bed reactorpcm Per cent millePSF Pool side facilityPWC Pressurized water capsulePWR Pressurized water reactorRODEO Rotatable device for the execution of

operational transientsSCKCEN Center for nuclear energy researchSFBR Sodium-cooled fast breeder reactor


SFR Sodium-cooled fast reactorTRIO Irradiation device with three thimblesTRIOX TRIO modified for irradiation of MOX

fuelsVIC Variable irradiation conditionsWP Work package

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This research paper has been cofinanced by the EuropeanUnion (European Social FundmdashESF) and by the Greeknational funds through the Operational Program ldquoEducationand Lifelong Learningrdquo of the National Strategic ReferenceFramework (NSRF)mdashResearch Funding Program ThalesInvesting in knowledge society through the European SocialFund

References

[1] MCNP Los Alamos National Laboratory MCNP-A generalMonteCarloN-Particle Transport Code SystemVersion 4C 2014httpsmcnplanlgov

[2] Ch de Raedt E Malambu B Verboomen and Th AoustldquoIncreasing complexity in the modeling of BR2 irradiationsrdquo inProceedings of the International Topical Meeting (PHYSOR rsquo00)Pittsburgh Pa USA May 2000

[3] G van den Eynde J Dekeyser L Vermeeren et al ldquoMutnuruNeutron screen technology overview neutron screen tech-nologyrdquo MTR+I3 Technical Report FI6O-656-036440 (2000)2009 restricted

[4] EC-JRC ldquoCharacteristics of the Installation and the IrradiationFacilitiesrdquo High Flux Reactor (HFR) Petten 2005 httpietjrceceuropaeusitesdefaultfilesdocumentsbrochureshfr miniblue bookpdf

[5] G Van Den Eynde J Dekeyser L Vermeeren et al ldquoNeutronscreen technology Simulation of fast neutron spectrum inMTRMTR+I3rdquo Tech Rep Contract Number FI6O-656-0364402009

[6] T S Ellis B Forget M S Kazimi T Newton and E PilatDesign of a Low Enrichment Enhanced Fast Flux Core for theMIT Research Reactor MIT Reactor Redesign Program Centerfor Advanced Nuclear Energy Systems MIT 2009

[7] M J Bell ORIGENmdashThe ORNL Isotope Generation and Deple-tion Code ORNL-4628 (CCC-217) union Carbide CorporationNuclear Division ORNL 1973

[8] G S Chang and R G Ambrosek ldquoHardening neutron spec-trum for advanced actinide transmutation experiments in theATRrdquo Radiation Protection Dosimetry vol 115 no 1ndash4 pp 63ndash68 2005

[9] G S Chang ldquoCadmium depletion impacts on hardening neu-tron spectrum for advanced fuel testing in ATRrdquo in Proceedingsof the International Conference on Mathematics and Compu-tational Methods Applied to Nuclear Science and Engineering(MampC rsquo11) Rio de Janeiro Brazil May 2011

[10] F M Marshall The Advanced Test Reactor Capabilities andExperiments Idaho National Laboratory 2008 httpscienceenergygovsimmedianppdfresearchidpraThe20Advanced20Test20Reactor20Capabilities20and20Experimentspdf

[11] R J Ellis ldquoComparison of calculated and measured neutronfluence in fuelcladding irradiation experiments in HFIRrdquoTransactions of the American Nuclear Society vol 105 pp 808ndash810 2011

[12] J R Parry ldquoDesigning a gas test loop for the advanced testreactorrdquo Transactions of the American Nuclear Society vol 93pp 662ndash663 2005

[13] INL Boosted Fast Flux Loop Final Report INLEXT-09-16413Fuels Performance and Design Department INL 2009

[14] G R Longhurst D P Guillen J R Parry D L Porter and BW Wallace ldquoWallace boosted fast flux loop alternative coolingassessmentrdquo NLEXT-07-12994 Idaho National Laboratory2007

[15] CEA OSIRIS Nuclear Reactors and Services Department2005 httpwwwcadceafrrjhAdd-Onosiris gbpdf

[16] F W Ingram A J Palmer and D J Stites ldquoTemperaturecontrolled material irradiation in the advanced test reactorrdquoJournal of Nuclear Materials vol 258-263 pp 362ndash366 1998

[17] A Horvath and A Brolly ldquoBrolly neutron screen technologyreport evaluation of new types of absorbers MTR+I3rdquo TechRep FI6O-656-036440 2009

[18] J McDuffee R Hobbs L Ott D Spellman D Heatherly andR J Ellis ldquoIrradiation of advanced light water reactor fuelin the high flux isotope reactorrdquo FY Annual Report (05015)Laboratory Directed Research and Development ProgramORNL 2009

[19] D P Guillen D L Porter J R Parry and H Ban ldquoIn-pileexperiment of a new hafnium aluminide composite material toenable fast neutron testing in the Advanced Test Reactorrdquo inProceeding of the International Congress on Advances in NuclearPower Plants 2010 (ICAPP 10) pp 778ndash784 San Diego CalifUSA June 2010

[20] IAEA ldquoFuel behavior under transient and LOCA conditionsrdquoin Proceedings of the Technical Committee Meeting HaldenNorway November 2002

[21] G S Chang R G Ambrosek and F W Ingram ldquoATR Al-Bneutron filter design for fusion material experimentrdquo FusionEngineering and Design vol 63-64 pp 481ndash485 2002

[22] R Szekely A Horvath F Gillemot M Horvath and D AntokldquoNew irradiation device at the Budapest Neutron Center(BNC)rdquo 2013 httpwwwiaeaorgOurWorkSTNENEFWTechnical AreasNFCdocumentsTM-Smolenice-2011TM-Posters szekelyrichard poster TM HOTLAB SMOLNICE2011 maypdf

[23] J L McDuffee J C Gehin R J Ellis et al ldquoPrimm III proposedfuel pin irradiation facilities for the high flux isotope reactorrdquo inProceedings of the International Congress on Advances in NuclearPower Plants (ICAPP rsquo08) Anaheim Calif USA Paper 8424June 2008

[24] N Xoubi and R T Primm IIIModeling of the High Flux IsotopeReactor Cycle 400 ORNL Oak Ridge Tenn USA 2004

[25] C Gehin R J Ellis and J McDuffe ldquo Development of a FastSpectrum Irradiation Facility for Fuels Development in theHigh Flux Isotope Reactorrdquo 2013

[26] SCK-CEN ldquoPWCCCD Pressurized Water CapsuleCyclingand Calibration Devicerdquo


[27] L Vermeeren P Benoit and J Dekeyser ldquoFinal report onthe VANESSA-RODEO design fuel power transient systemdevelopments-design of in core devicesrdquo Tech Rep MTR+I3FI6O-656-036440 2009

[28] D Moulin L Vermeeren K Bakker C Roth and J L PRodriguez ldquoFuel testing devices power transient systems andneutr on screen development for LWRs assessment of the typeof transients to be achievedrdquo MTR+I3 Technical Report FI6O-656-036440 2007

[29] SCK-CEN ldquoNew Irradiation Infrastructures Fuel Transientrdquo2005 httpwwwiaeaorginiscollectionNCLCollectionStorePublic3609736097559pdf

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of


Journal ofPetroleum Engineering


Industrial EngineeringJournal of


Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of


Journal of


Renewable Energy

Submit your manuscripts athttpwwwhindawicom


StructuresJournal of


RotatingMachinery


EnergyJournal of


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Nuclear InstallationsScience and Technology of


Solar EnergyJournal of


Wind EnergyJournal of


Nuclear EnergyInternational Journal of


High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


reproduce the irradiation conditions prevailing in a sodium-cooled fast reactor (SFR) environment or in a sodium-cooledfast breeder reactor (SFBR) coolant loops and booster fuelsare combined in the irradiation facility This work furtherinvestigates the power transition facilities that are also basedon neutron screens utilization where also thermal neutronabsorbers are used By varying the absorberrsquos concentrationpower transient on the irradiation sample is achieved Theutilization of variable screens is necessary in order to testthe fuel behavior when exposed to sudden power variationconditions

The report is divided into two sections depending onthe form of the absorbing material used that is solid andfluid neutron screensThe first section is dedicated to neutronscreens which use solid absorbing material and serve forsimulation of fast neutron spectrumconditions In the secondsection neutron screens utilized for power transients arepresented Solid neutron screens can provide larger powertransients than fluid screens since they have higher densitybut their utilization is complex Fluid absorbing materialsare often preferred for this purpose since their screen-ing capability can easily change by varying their pressureandor concentration Several successful examples of neutronscreens performance are reviewed while problems appearingin specific cases are pointed out Computational resultsobtained in order to examine the various neutron screensbehavior using mainly MCNP code [1] are also review-ed

2 Solid Neutron Screens

In this chapter neutron screens which use a solid mate-rial are presented four solid thermal neutrons absorbingmaterials are reported that is cadmium hafnium boronand europium All of them are materials widely used innuclear reactors in several applications and all of them haveadequate thermal neutron absorption cross-sections In eachcase the selection of the appropriate material depends onthe requirements of the experiment the available space forscreen loading the safety issues related to screen loadingand thematerials compatibility Additionally for the materialselection the accumulated experience gained using the spe-cific material for other reactor operations is also exploitedThe factors that should be taken into account in a neutronscreen design are the geometrical configuration of the screenits depletion rate the reactivity effect caused by its insertion inthe core the screen cooling medium the acting field and therequired conditionsThe impact that a neutron screen has onreactor operation (reactivity insertion) and on neighboringexperiments if any should be thoroughly analyzed In thisreport the last issue has not been raised

The solid screens are classified bymaterial and are dividedinto subclasses depending on whether they have already beenused or they are under development or study In cases forwhich neutron screens are under development or study theparameters that should be considered for the safety andeffective neutron screen design are still under investigationand have not accurately been predicted

21 Cadmium Neutron Screens Cadmium is a materialwidely used for thermal neutron filtering because of itsexcellent thermal neutron capture capability Its utilizationin neutron screen technology is very common since thereactors community is familiar with itsmechanical propertiesand other technological issues However cadmium screenconstruction is complex from the engineering point of viewbecause of its low melting point and its large thermalexpansion Because of its extremely high thermal neutroncross-section a slightly thin neutron screen is sufficient totailor the neutron flux distribution in most cases The morethermal neutron-absorbing cadmium isotope is 113Cd whichconstitutes only 12 of the natural cadmium In high neutronfluxes 113Cd is quickly depleted thus demanding frequentreplacement of the screen (or additional material) in orderto avoid unexpected increase of power deposited on theirradiated samples

Cadmium screens are being used for many years nowIn BR2 for instance most of the irradiations from the 1960suntil late 1980s were carried out in the framework of the fastreactor development program andmost of the irradiation rigscontained a cadmium thermal neutron-absorbing screen [2]

211 Cadmium Neutron Screens Already Being Used

(1) BelgianReactor 2 Center forNuclear Energy Research (BR2SCKCEN) In BR2 core (Figure 1) at SCKCEN a Cd screenwas installed around a large Na loop (hosting a single fastreactor fuel pin) which was already surrounded by a gaseous3He screen at variable pressure The experiment named VIC(variable irradiation conditions) was installed in a standard842mm channel of BR2 (Figure 1) and its utilization aimedat liquid-metal fast breeder reactor (LMFBR) fuel pins testingunder transient operating conditions The 3He gas screenserves for fuel power transient while the Cd screen providesa fast spectrum environment by cutting off the thermalneutrons The optimization of the neutronic design of theloop was done by calculating an optimal thickness of thewater annuli between the 3He and Cd screens in order toallow for a certain rethermalization (so that the 3He screenwould be able to induce a transient) keeping at the same timethe thermal component of the neutron flux low enough so asto be a representative of a SFR [3] Utilization of 3He screenfor power transients in VIC is also examined in Section 3

Figure 2 shows the neutron spectra in a BR2 experimentwith (red line) and without (dashed line) Cd screen locatedaxially in a fuel element channelThe installation of the screencuts off the thermal component of the neutron spectrumwhereas it has practically no effect on the high fast flux thusleading the radial fission density distributions across fuel pinbundles and inside the fuel pins themselves to become muchflatter and therefore better simulating the conditions of fastreactor

An additional experiment with cadmium screen namedMOL 7D was installed in the central H1 channel of BR2(Figure 1) in order to study the safety parameters of a SFBRThe MOL 7D loop contained 19 fuel pins in a triangularpitch arrangement of 1 (central) + 6 (inner) + 12 (outer)


Fuel element

Control rod

Reflector

L0P341

P319

K349 K11P19

N330H337 G0 H23

N30

H323 F346

D0

F14

F46

H37

B

A330

C341

A30

C41

C79

C19

E30

C101

C139

C161

F166

K169

K109

L120

G120

K191

L180

G180

D180

B180

P161

P101

P199

D120

F106

A150A210

C190

F194

G60

K49

L60

E330

C319

B300

B240

C221

F314

K311L300

K251P259

L240

D300G300

F254

G240

C281

C259

D240

A270

P41

D60

B60

B120

A90

0

H1

H4 H3

H5 H2





035

030

025

020

015

010

005

000

10Eminus03

10Eminus02

10Eminus01

10E+00

10E+01

10E+02

10E+03

10E+04

10E+05

10E+06

10E+07

Energy (eV)

Flux

per

uni

t let

harg

y







Cadmium screen

SodiumShroud







2TiO3








Beryllium

Fuel element

Control element

A B C D E F G H I

1

2

3

4

5

6

7

8

9

5

6

7

8

9

10

PSFW

122E + 14

113E + 14

132E + 14

174E + 14

103E + 14

135E + 14

292E + 14

177E + 14

237E + 14

137E + 14

132E + 14

173E + 14

189E + 14

115E + 14

201E + 14

948E + 14

178E + 14

346E + 13

152E + 14

437E + 13

150E + 14

442E + 13

142E + 14

411E + 13

159E + 14

300E + 13

155E + 14

167E + 13

870E + 13

802E + 13

542E + 13

376E + 13

623E + 13

868E + 13

607E + 13

616E + 13

745E + 13

102E + 14

591E + 13

620E + 13

575E + 13

836E + 13

826E + 13

755E + 13

517E + 13

374E + 13

ΦthermalΦfast







150

100

0

0 100 200 300 400 500 600 700 800


Pow

er (W

cc)


ABC

DE




MTi 75MTi 30

1014

1013

1012

1011

Neu

tron

flux

10minus3

10minus2

10minus1

100

101

102

103

104

105

106

107

Energy (eV)



100E + 14

100E + 13

100E + 12

100E + 11

100E + 10

100E + 09Nor

mal

ized

(to10

MW

) neu

tron

flux

per u

nit l

etha

rgy

100Eminus09

100Eminus08

100Eminus07

100Eminus06

100Eminus05

100Eminus04

100Eminus03

100Eminus02

100Eminus01

100E+00

100E+01

100E+02

Energy (MeV)






18

1920

21

2223

24

NW N NE

W

SW S SE

I I I

I

II

I

I

I

I

I

I

IIIII

I

I

I

I

I

I I1

12

73

45

6

23

4

5

6

7

8

9101112

13

14

15

16

17

Small B position






Safety rod





H position(159 cm)



diameter)

Berylliumreflector

Neckshim rodhousing


Core reflectortank


B1

B1

B1

B2

B4

B4B5

B6

B7

B8

B9

B10

(127 cm or 5998400998400











10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus10

10Eminus8

10Eminus6

10Eminus4

10Eminus2

10E+0

10E+2

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)



1600

1400

1200

1000

800

400

600

200

00 2 4 6 8 10 12 14 16


Pow

er (W

cm

3)

Axial position





35E + 14

30E + 14

25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

1E

minus09

1E

minus07

1E

minus05

1E

minus03

1E

minus01

1E

+01

1E

+03



25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

0mm Hf1mm Hf2mm Hf

3mm Hf4mm Hf


Energy (MeV)








120

100

80

60

40

20

0

120

100

80

60

40

20

00 1 2 3 4

Nor

mal

ized

pow

er (

)


Flux

leth

argy

at th

erm

al p

eak

()













2gases have



Target bundle

Horizontal

Peripheral target

in flux trap

beam tube

position


Control region

Large vertical


Small vertical


Large removable


HB-1

HB-2

HB-3

HB-4

0 2 4 6

(Inches)


Basket assembly

Capsuleassembly











FT 403 258




125998400998400 OD 125998400998400 ID

10998400998400 OD test space





6061 aluminum clad





North


Gas gap 004998400998400 thick

(He sim30 psig)

Hegas


Water (0078998400998400 or sim2mm)


60

50

40

30

20

10

00 2 4 6 8 10 12

1055

1050

1045

1040

1035

1030

1025

Fast

to th

erm

al ra

tio

Fast

flux

(1015

ncm

2s

)

Hafnium ()


60

50

40

30

20

10

00 2 4 6 8 10 12

16

14

12

10

8

6

4

2

0

Hea

t den

sity

(Wc

m3)

Hea

t rat

e (W

g)

Hafnium ()











NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















Fuel element

Control rod

Reflector

L0P341

P319

K349 K11P19

N330H337 G0 H23

N30

H323 F346

D0

F14

F46

H37

B

A330

C341

A30

C41

C79

C19

E30

C101

C139

C161

F166

K169

K109

L120

G120

K191

L180

G180

D180

B180

P161

P101

P199

D120

F106

A150A210

C190

F194

G60

K49

L60

E330

C319

B300

B240

C221

F314

K311L300

K251P259

L240

D300G300

F254

G240

C281

C259

D240

A270

P41

D60

B60

B120

A90

0

H1

H4 H3

H5 H2





035

030

025

020

015

010

005

000

10Eminus03

10Eminus02

10Eminus01

10E+00

10E+01

10E+02

10E+03

10E+04

10E+05

10E+06

10E+07

Energy (eV)

Flux

per

uni

t let

harg

y







Cadmium screen

SodiumShroud







2TiO3








Beryllium

Fuel element

Control element

A B C D E F G H I

1

2

3

4

5

6

7

8

9

5

6

7

8

9

10

PSFW

122E + 14

113E + 14

132E + 14

174E + 14

103E + 14

135E + 14

292E + 14

177E + 14

237E + 14

137E + 14

132E + 14

173E + 14

189E + 14

115E + 14

201E + 14

948E + 14

178E + 14

346E + 13

152E + 14

437E + 13

150E + 14

442E + 13

142E + 14

411E + 13

159E + 14

300E + 13

155E + 14

167E + 13

870E + 13

802E + 13

542E + 13

376E + 13

623E + 13

868E + 13

607E + 13

616E + 13

745E + 13

102E + 14

591E + 13

620E + 13

575E + 13

836E + 13

826E + 13

755E + 13

517E + 13

374E + 13

ΦthermalΦfast







150

100

0

0 100 200 300 400 500 600 700 800


Pow

er (W

cc)


ABC

DE




MTi 75MTi 30

1014

1013

1012

1011

Neu

tron

flux

10minus3

10minus2

10minus1

100

101

102

103

104

105

106

107

Energy (eV)



100E + 14

100E + 13

100E + 12

100E + 11

100E + 10

100E + 09Nor

mal

ized

(to10

MW

) neu

tron

flux

per u

nit l

etha

rgy

100Eminus09

100Eminus08

100Eminus07

100Eminus06

100Eminus05

100Eminus04

100Eminus03

100Eminus02

100Eminus01

100E+00

100E+01

100E+02

Energy (MeV)






18

1920

21

2223

24

NW N NE

W

SW S SE

I I I

I

II

I

I

I

I

I

I

IIIII

I

I

I

I

I

I I1

12

73

45

6

23

4

5

6

7

8

9101112

13

14

15

16

17

Small B position






Safety rod





H position(159 cm)



diameter)

Berylliumreflector

Neckshim rodhousing


Core reflectortank


B1

B1

B1

B2

B4

B4B5

B6

B7

B8

B9

B10

(127 cm or 5998400998400











10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus10

10Eminus8

10Eminus6

10Eminus4

10Eminus2

10E+0

10E+2

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)



1600

1400

1200

1000

800

400

600

200

00 2 4 6 8 10 12 14 16


Pow

er (W

cm

3)

Axial position





35E + 14

30E + 14

25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

1E

minus09

1E

minus07

1E

minus05

1E

minus03

1E

minus01

1E

+01

1E

+03



25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

0mm Hf1mm Hf2mm Hf

3mm Hf4mm Hf


Energy (MeV)








120

100

80

60

40

20

0

120

100

80

60

40

20

00 1 2 3 4

Nor

mal

ized

pow

er (

)


Flux

leth

argy

at th

erm

al p

eak

()













2gases have



Target bundle

Horizontal

Peripheral target

in flux trap

beam tube

position


Control region

Large vertical


Small vertical


Large removable


HB-1

HB-2

HB-3

HB-4

0 2 4 6

(Inches)


Basket assembly

Capsuleassembly











FT 403 258




125998400998400 OD 125998400998400 ID

10998400998400 OD test space





6061 aluminum clad





North


Gas gap 004998400998400 thick

(He sim30 psig)

Hegas


Water (0078998400998400 or sim2mm)


60

50

40

30

20

10

00 2 4 6 8 10 12

1055

1050

1045

1040

1035

1030

1025

Fast

to th

erm

al ra

tio

Fast

flux

(1015

ncm

2s

)

Hafnium ()


60

50

40

30

20

10

00 2 4 6 8 10 12

16

14

12

10

8

6

4

2

0

Hea

t den

sity

(Wc

m3)

Hea

t rat

e (W

g)

Hafnium ()











NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















Cadmium screen

SodiumShroud







2TiO3








Beryllium

Fuel element

Control element

A B C D E F G H I

1

2

3

4

5

6

7

8

9

5

6

7

8

9

10

PSFW

122E + 14

113E + 14

132E + 14

174E + 14

103E + 14

135E + 14

292E + 14

177E + 14

237E + 14

137E + 14

132E + 14

173E + 14

189E + 14

115E + 14

201E + 14

948E + 14

178E + 14

346E + 13

152E + 14

437E + 13

150E + 14

442E + 13

142E + 14

411E + 13

159E + 14

300E + 13

155E + 14

167E + 13

870E + 13

802E + 13

542E + 13

376E + 13

623E + 13

868E + 13

607E + 13

616E + 13

745E + 13

102E + 14

591E + 13

620E + 13

575E + 13

836E + 13

826E + 13

755E + 13

517E + 13

374E + 13

ΦthermalΦfast







150

100

0

0 100 200 300 400 500 600 700 800


Pow

er (W

cc)


ABC

DE




MTi 75MTi 30

1014

1013

1012

1011

Neu

tron

flux

10minus3

10minus2

10minus1

100

101

102

103

104

105

106

107

Energy (eV)



100E + 14

100E + 13

100E + 12

100E + 11

100E + 10

100E + 09Nor

mal

ized

(to10

MW

) neu

tron

flux

per u

nit l

etha

rgy

100Eminus09

100Eminus08

100Eminus07

100Eminus06

100Eminus05

100Eminus04

100Eminus03

100Eminus02

100Eminus01

100E+00

100E+01

100E+02

Energy (MeV)






18

1920

21

2223

24

NW N NE

W

SW S SE

I I I

I

II

I

I

I

I

I

I

IIIII

I

I

I

I

I

I I1

12

73

45

6

23

4

5

6

7

8

9101112

13

14

15

16

17

Small B position






Safety rod





H position(159 cm)



diameter)

Berylliumreflector

Neckshim rodhousing


Core reflectortank


B1

B1

B1

B2

B4

B4B5

B6

B7

B8

B9

B10

(127 cm or 5998400998400











10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus10

10Eminus8

10Eminus6

10Eminus4

10Eminus2

10E+0

10E+2

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)



1600

1400

1200

1000

800

400

600

200

00 2 4 6 8 10 12 14 16


Pow

er (W

cm

3)

Axial position





35E + 14

30E + 14

25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

1E

minus09

1E

minus07

1E

minus05

1E

minus03

1E

minus01

1E

+01

1E

+03



25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

0mm Hf1mm Hf2mm Hf

3mm Hf4mm Hf


Energy (MeV)








120

100

80

60

40

20

0

120

100

80

60

40

20

00 1 2 3 4

Nor

mal

ized

pow

er (

)


Flux

leth

argy

at th

erm

al p

eak

()













2gases have



Target bundle

Horizontal

Peripheral target

in flux trap

beam tube

position


Control region

Large vertical


Small vertical


Large removable


HB-1

HB-2

HB-3

HB-4

0 2 4 6

(Inches)


Basket assembly

Capsuleassembly











FT 403 258




125998400998400 OD 125998400998400 ID

10998400998400 OD test space





6061 aluminum clad





North


Gas gap 004998400998400 thick

(He sim30 psig)

Hegas


Water (0078998400998400 or sim2mm)


60

50

40

30

20

10

00 2 4 6 8 10 12

1055

1050

1045

1040

1035

1030

1025

Fast

to th

erm

al ra

tio

Fast

flux

(1015

ncm

2s

)

Hafnium ()


60

50

40

30

20

10

00 2 4 6 8 10 12

16

14

12

10

8

6

4

2

0

Hea

t den

sity

(Wc

m3)

Hea

t rat

e (W

g)

Hafnium ()











NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















Beryllium

Fuel element

Control element

A B C D E F G H I

1

2

3

4

5

6

7

8

9

5

6

7

8

9

10

PSFW

122E + 14

113E + 14

132E + 14

174E + 14

103E + 14

135E + 14

292E + 14

177E + 14

237E + 14

137E + 14

132E + 14

173E + 14

189E + 14

115E + 14

201E + 14

948E + 14

178E + 14

346E + 13

152E + 14

437E + 13

150E + 14

442E + 13

142E + 14

411E + 13

159E + 14

300E + 13

155E + 14

167E + 13

870E + 13

802E + 13

542E + 13

376E + 13

623E + 13

868E + 13

607E + 13

616E + 13

745E + 13

102E + 14

591E + 13

620E + 13

575E + 13

836E + 13

826E + 13

755E + 13

517E + 13

374E + 13

ΦthermalΦfast







150

100

0

0 100 200 300 400 500 600 700 800


Pow

er (W

cc)


ABC

DE




MTi 75MTi 30

1014

1013

1012

1011

Neu

tron

flux

10minus3

10minus2

10minus1

100

101

102

103

104

105

106

107

Energy (eV)



100E + 14

100E + 13

100E + 12

100E + 11

100E + 10

100E + 09Nor

mal

ized

(to10

MW

) neu

tron

flux

per u

nit l

etha

rgy

100Eminus09

100Eminus08

100Eminus07

100Eminus06

100Eminus05

100Eminus04

100Eminus03

100Eminus02

100Eminus01

100E+00

100E+01

100E+02

Energy (MeV)






18

1920

21

2223

24

NW N NE

W

SW S SE

I I I

I

II

I

I

I

I

I

I

IIIII

I

I

I

I

I

I I1

12

73

45

6

23

4

5

6

7

8

9101112

13

14

15

16

17

Small B position






Safety rod





H position(159 cm)



diameter)

Berylliumreflector

Neckshim rodhousing


Core reflectortank


B1

B1

B1

B2

B4

B4B5

B6

B7

B8

B9

B10

(127 cm or 5998400998400











10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus10

10Eminus8

10Eminus6

10Eminus4

10Eminus2

10E+0

10E+2

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)



1600

1400

1200

1000

800

400

600

200

00 2 4 6 8 10 12 14 16


Pow

er (W

cm

3)

Axial position





35E + 14

30E + 14

25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

1E

minus09

1E

minus07

1E

minus05

1E

minus03

1E

minus01

1E

+01

1E

+03



25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

0mm Hf1mm Hf2mm Hf

3mm Hf4mm Hf


Energy (MeV)








120

100

80

60

40

20

0

120

100

80

60

40

20

00 1 2 3 4

Nor

mal

ized

pow

er (

)


Flux

leth

argy

at th

erm

al p

eak

()













2gases have



Target bundle

Horizontal

Peripheral target

in flux trap

beam tube

position


Control region

Large vertical


Small vertical


Large removable


HB-1

HB-2

HB-3

HB-4

0 2 4 6

(Inches)


Basket assembly

Capsuleassembly











FT 403 258




125998400998400 OD 125998400998400 ID

10998400998400 OD test space





6061 aluminum clad





North


Gas gap 004998400998400 thick

(He sim30 psig)

Hegas


Water (0078998400998400 or sim2mm)


60

50

40

30

20

10

00 2 4 6 8 10 12

1055

1050

1045

1040

1035

1030

1025

Fast

to th

erm

al ra

tio

Fast

flux

(1015

ncm

2s

)

Hafnium ()


60

50

40

30

20

10

00 2 4 6 8 10 12

16

14

12

10

8

6

4

2

0

Hea

t den

sity

(Wc

m3)

Hea

t rat

e (W

g)

Hafnium ()











NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















150

100

0

0 100 200 300 400 500 600 700 800


Pow

er (W

cc)


ABC

DE




MTi 75MTi 30

1014

1013

1012

1011

Neu

tron

flux

10minus3

10minus2

10minus1

100

101

102

103

104

105

106

107

Energy (eV)



100E + 14

100E + 13

100E + 12

100E + 11

100E + 10

100E + 09Nor

mal

ized

(to10

MW

) neu

tron

flux

per u

nit l

etha

rgy

100Eminus09

100Eminus08

100Eminus07

100Eminus06

100Eminus05

100Eminus04

100Eminus03

100Eminus02

100Eminus01

100E+00

100E+01

100E+02

Energy (MeV)






18

1920

21

2223

24

NW N NE

W

SW S SE

I I I

I

II

I

I

I

I

I

I

IIIII

I

I

I

I

I

I I1

12

73

45

6

23

4

5

6

7

8

9101112

13

14

15

16

17

Small B position






Safety rod





H position(159 cm)



diameter)

Berylliumreflector

Neckshim rodhousing


Core reflectortank


B1

B1

B1

B2

B4

B4B5

B6

B7

B8

B9

B10

(127 cm or 5998400998400











10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus10

10Eminus8

10Eminus6

10Eminus4

10Eminus2

10E+0

10E+2

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)



1600

1400

1200

1000

800

400

600

200

00 2 4 6 8 10 12 14 16


Pow

er (W

cm

3)

Axial position





35E + 14

30E + 14

25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

1E

minus09

1E

minus07

1E

minus05

1E

minus03

1E

minus01

1E

+01

1E

+03



25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

0mm Hf1mm Hf2mm Hf

3mm Hf4mm Hf


Energy (MeV)








120

100

80

60

40

20

0

120

100

80

60

40

20

00 1 2 3 4

Nor

mal

ized

pow

er (

)


Flux

leth

argy

at th

erm

al p

eak

()













2gases have



Target bundle

Horizontal

Peripheral target

in flux trap

beam tube

position


Control region

Large vertical


Small vertical


Large removable


HB-1

HB-2

HB-3

HB-4

0 2 4 6

(Inches)


Basket assembly

Capsuleassembly











FT 403 258




125998400998400 OD 125998400998400 ID

10998400998400 OD test space





6061 aluminum clad





North


Gas gap 004998400998400 thick

(He sim30 psig)

Hegas


Water (0078998400998400 or sim2mm)


60

50

40

30

20

10

00 2 4 6 8 10 12

1055

1050

1045

1040

1035

1030

1025

Fast

to th

erm

al ra

tio

Fast

flux

(1015

ncm

2s

)

Hafnium ()


60

50

40

30

20

10

00 2 4 6 8 10 12

16

14

12

10

8

6

4

2

0

Hea

t den

sity

(Wc

m3)

Hea

t rat

e (W

g)

Hafnium ()











NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















18

1920

21

2223

24

NW N NE

W

SW S SE

I I I

I

II

I

I

I

I

I

I

IIIII

I

I

I

I

I

I I1

12

73

45

6

23

4

5

6

7

8

9101112

13

14

15

16

17

Small B position






Safety rod





H position(159 cm)



diameter)

Berylliumreflector

Neckshim rodhousing


Core reflectortank


B1

B1

B1

B2

B4

B4B5

B6

B7

B8

B9

B10

(127 cm or 5998400998400











10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus10

10Eminus8

10Eminus6

10Eminus4

10Eminus2

10E+0

10E+2

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)



1600

1400

1200

1000

800

400

600

200

00 2 4 6 8 10 12 14 16


Pow

er (W

cm

3)

Axial position





35E + 14

30E + 14

25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

1E

minus09

1E

minus07

1E

minus05

1E

minus03

1E

minus01

1E

+01

1E

+03



25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

0mm Hf1mm Hf2mm Hf

3mm Hf4mm Hf


Energy (MeV)








120

100

80

60

40

20

0

120

100

80

60

40

20

00 1 2 3 4

Nor

mal

ized

pow

er (

)


Flux

leth

argy

at th

erm

al p

eak

()













2gases have



Target bundle

Horizontal

Peripheral target

in flux trap

beam tube

position


Control region

Large vertical


Small vertical


Large removable


HB-1

HB-2

HB-3

HB-4

0 2 4 6

(Inches)


Basket assembly

Capsuleassembly











FT 403 258




125998400998400 OD 125998400998400 ID

10998400998400 OD test space





6061 aluminum clad





North


Gas gap 004998400998400 thick

(He sim30 psig)

Hegas


Water (0078998400998400 or sim2mm)


60

50

40

30

20

10

00 2 4 6 8 10 12

1055

1050

1045

1040

1035

1030

1025

Fast

to th

erm

al ra

tio

Fast

flux

(1015

ncm

2s

)

Hafnium ()


60

50

40

30

20

10

00 2 4 6 8 10 12

16

14

12

10

8

6

4

2

0

Hea

t den

sity

(Wc

m3)

Hea

t rat

e (W

g)

Hafnium ()











NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus10

10Eminus8

10Eminus6

10Eminus4

10Eminus2

10E+0

10E+2

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)



1600

1400

1200

1000

800

400

600

200

00 2 4 6 8 10 12 14 16


Pow

er (W

cm

3)

Axial position





35E + 14

30E + 14

25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

1E

minus09

1E

minus07

1E

minus05

1E

minus03

1E

minus01

1E

+01

1E

+03



25E + 14

20E + 14

15E + 14

10E + 14

50E + 13

00E + 00

Flux

leth

argy

0mm Hf1mm Hf2mm Hf

3mm Hf4mm Hf


Energy (MeV)








120

100

80

60

40

20

0

120

100

80

60

40

20

00 1 2 3 4

Nor

mal

ized

pow

er (

)


Flux

leth

argy

at th

erm

al p

eak

()













2gases have



Target bundle

Horizontal

Peripheral target

in flux trap

beam tube

position


Control region

Large vertical


Small vertical


Large removable


HB-1

HB-2

HB-3

HB-4

0 2 4 6

(Inches)


Basket assembly

Capsuleassembly











FT 403 258




125998400998400 OD 125998400998400 ID

10998400998400 OD test space





6061 aluminum clad





North


Gas gap 004998400998400 thick

(He sim30 psig)

Hegas


Water (0078998400998400 or sim2mm)


60

50

40

30

20

10

00 2 4 6 8 10 12

1055

1050

1045

1040

1035

1030

1025

Fast

to th

erm

al ra

tio

Fast

flux

(1015

ncm

2s

)

Hafnium ()


60

50

40

30

20

10

00 2 4 6 8 10 12

16

14

12

10

8

6

4

2

0

Hea

t den

sity

(Wc

m3)

Hea

t rat

e (W

g)

Hafnium ()











NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















120

100

80

60

40

20

0

120

100

80

60

40

20

00 1 2 3 4

Nor

mal

ized

pow

er (

)


Flux

leth

argy

at th

erm

al p

eak

()













2gases have



Target bundle

Horizontal

Peripheral target

in flux trap

beam tube

position


Control region

Large vertical


Small vertical


Large removable


HB-1

HB-2

HB-3

HB-4

0 2 4 6

(Inches)


Basket assembly

Capsuleassembly











FT 403 258




125998400998400 OD 125998400998400 ID

10998400998400 OD test space





6061 aluminum clad





North


Gas gap 004998400998400 thick

(He sim30 psig)

Hegas


Water (0078998400998400 or sim2mm)


60

50

40

30

20

10

00 2 4 6 8 10 12

1055

1050

1045

1040

1035

1030

1025

Fast

to th

erm

al ra

tio

Fast

flux

(1015

ncm

2s

)

Hafnium ()


60

50

40

30

20

10

00 2 4 6 8 10 12

16

14

12

10

8

6

4

2

0

Hea

t den

sity

(Wc

m3)

Hea

t rat

e (W

g)

Hafnium ()











NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















Target bundle

Horizontal

Peripheral target

in flux trap

beam tube

position


Control region

Large vertical


Small vertical


Large removable


HB-1

HB-2

HB-3

HB-4

0 2 4 6

(Inches)


Basket assembly

Capsuleassembly











FT 403 258




125998400998400 OD 125998400998400 ID

10998400998400 OD test space





6061 aluminum clad





North


Gas gap 004998400998400 thick

(He sim30 psig)

Hegas


Water (0078998400998400 or sim2mm)


60

50

40

30

20

10

00 2 4 6 8 10 12

1055

1050

1045

1040

1035

1030

1025

Fast

to th

erm

al ra

tio

Fast

flux

(1015

ncm

2s

)

Hafnium ()


60

50

40

30

20

10

00 2 4 6 8 10 12

16

14

12

10

8

6

4

2

0

Hea

t den

sity

(Wc

m3)

Hea

t rat

e (W

g)

Hafnium ()











NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















125998400998400 OD 125998400998400 ID

10998400998400 OD test space





6061 aluminum clad





North


Gas gap 004998400998400 thick

(He sim30 psig)

Hegas


Water (0078998400998400 or sim2mm)


60

50

40

30

20

10

00 2 4 6 8 10 12

1055

1050

1045

1040

1035

1030

1025

Fast

to th

erm

al ra

tio

Fast

flux

(1015

ncm

2s

)

Hafnium ()


60

50

40

30

20

10

00 2 4 6 8 10 12

16

14

12

10

8

6

4

2

0

Hea

t den

sity

(Wc

m3)

Hea

t rat

e (W

g)

Hafnium ()











NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of



















NorthA B C D

D

E

E

F

F

G

G

H

H

J

J

K

K

L

L

M

M

N

N

D

E

F

G

H

J

K

L

M

N

O P

10

20

30

40

50

60

70

80

Molfi

REA OBE

Pied

percors

OBEIrma 4

OBEIrma 5

prod

REAprod

REAprod

Isabelle 1

Tano

xos 1

Griffonos 1

03

Molfi01

Quad

Diodons

03

11

1

1

12

11

10

9

12

11

10

9

22

2

233

3

344

4

45

5

6

6

7

Bariton

eauBo teı a




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of




















Water coolant gaps






411 BC


Gas channel tube

(256 ID)





4C shield [22]













10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of






















10E minus 1

10E minus 2

10E minus 3

10E minus 4

10E minus 5

10E minus 6

10E minus 7

10E minus 8

10E minus 9

10Eminus9

10Eminus7

10Eminus5

10Eminus3

10Eminus1

10E+1

Nor

mal

ized

flux

per

leth

argy

Energy (MeV)





VacuumBe reflector

Be displacers

Water





050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















050

040

030

020

010

000

Spec

trum

[1]

00001

01

05

10

200

Energy (MeV)







1014

1013

1012

1011

Neu

tron

flux

(1c

m2s

)

00001

01

0510

200

Energy (MeV)





3BO3




3BO3ones





Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















Coolant channel

Eu2O3

Stainless steel

R 5300 cm

R 4336 cm

R3257

cmR2750

cm

R2575

cm

R 12900 cm

R 14300 cm

R 15444

cmR18281 cm

R19425

cm

R19910

cm

R20670

cm

R3307 cm

Fuel

Fuel

Fuel


14

12

10

08

06

04

02

00

Flux

leth

argy

(au

)







(1) BR2 SCKCEN






He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of



















He screen

Fuel segment


Al plug



Flow measurement



CCD module




3and liquid H

3BO3




(1) HFR Petten








3










VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















VICloop


Na containment tube




BR2 cooling water

Protecting tube


Cooling sleeve





Normal transient

Pow

er (

)Po

wer

()

Pow

er (

)Po

wer

()

100

Time


125

100

10min

Time

Ramp margin

150

100

Time

Power cycling

100

Time

1000 cycles4h

4h

















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of






















Inner tube

PWC


3022223232

mmmmmmmmmmmmmmmmmm

PWC diameter


mmmmmmmmmmmmmm









3BO3should be



3BO3


3BO3 the




3 and liquid H

3BO3

BF3and H














IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of


















IPS penetration

Worm gear

Skirt



Needles bearing




VANESSA outer tube





3 and H

3BO3 The last two














Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of

























Abbreviations












Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of






















Acknowledgments


References



































FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of

























FuelsJournal of







Advances in



Journal of


Renewable Energy





RotatingMachinery


EnergyJournal of

















Review Article Compilation of Existing Neutron Screen...

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Transcript of Review Article Compilation of Existing Neutron Screen...