XA04CI731INSTITUTE OF ATOMIC ENERGY

RESEARCH REACTOR CENTRE

Operational characteristics of research

reactor MARIA after modernisation.

Grzegorz KrLysztoszek

Paper to be presented at:

6 th Meeting of the International Group on Research Reactors, Taejon, The Republic of Korea

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Operational characteristics of research reactor MARIA after modernisation.

Grzegorz Krzysztoszek,

Head Reactor MARIA Operation Department Research Reactor Centre,

05-400 OTWOCK-�wierk POLAND

tel. 048(22) 7798488; fax 048(22) 7799700

Abstract

Polish high flux research reactor MARIA is a pool type reactor moderated with

beryllium and water and cooled with water. The fuel is 80% enriched uranium, in the shape of

multitube fuel elements, each tube made up of Ual, alloy in aluminum cladding.

MARIA reactor has been operated in the year of 1977-85 and then it was modernised

and again put into operation in December of 1992.

Reactor is used for radioisotope production and physical research on neutron beams.

Nominal power of the reactor is 30 MWtj, and its maximum thermal neutron flux is

equal to 45 1014 n- CM-2S-1.

After modernisation the reactor core was extended from 12 to 18 fuel channels. Within

the frame of nuclear fuel burn-up optimisation the high bum-ups of fuel up to ca. 45% have

been reached.

Irradiation of the target materials is linked mostly with the production of - P-32 J131

and Ir- 1 92.

Material investigation and dynamics of the crystal lattice by means of neutron

spectrometer at the neutron beams outlets of the reactor are conducted.

Radioactive products releases to the atmosphere were on the minimal level and they

were contained within one several percent of the annual release limit.

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1. INTRODUCTION

High flux research reactor MARIA is situated at wierk near Warsaw and operated bythe Institute of Atomic Energy.

Maria has been designed ad constructed by Polish industry. It is water and berylliummoderated, water cooled reactor of a pool type with pressurised fuel channels containingconcentric multi-tube assemblies of fuel elements.

MARIA has been designed with a high degree of flexibility to provide possibilities ofproduction of radioisotopes, of physical and iadiation experiments. Operational power is 30MW and thermal neutron flux in the centre of the core 4xI 018 n/M2S.

The main reactor possibilities are as follow:- testing of fuel and material for nuclear power stations,- production of radioisotopes,- neutron physics,- neutron activation analysis,- neutron radiography.First criticality of the MARIA reactor was reached in December 1974. The reactor was

in operation since 1975 until 1985. In July 1985 it was shout down for modernisation.Modernisation of the MARIA reactor as related to the core was connected with extension ofberyllium matrix from 20 to 48 blocks which was accomplished by the substitution of theretired graphite reflector blocks with the new beryllium ones. MARIA reactor was put againinto operation in 1993.

2. DESCRIPTION OF REACTOR MARIA

A vertical cross section across the reactor pool is shown in. Fig. 1. The reactor corefuel and loop channels, head 'ers, and connections between the headers and fuel channels are allsubmerged in the pool under a layer of water ensuring sufficient radiation shielding above thecore.

The characteristic design feature of the core is a conical arrangement of fuel channels.The fuel channels are situated in beryllium matrix made of blocks of II 0 cm height andenclosed by a lateral reflector made of graphite blocks in aluminium cans. Some of the blockscontain horizontal holes for extraction of neutron beams from the reflector to the horizontaltubes penetrating the reactor lateral shield. A view of the reactor core and reflector from aboveis shown in Fig. 2

In area of reftetor core and reflector tere is a number of vertical irradiation channels,made of altiminium tubes. The reactor core layout, shown in Fig. 3 gives an example of coremanagement, which fulfils the needs of radioisotope production and several experimentalprograms.

Fuel assembly is shown in Fig. 4 It contains six tubes with uranium enriched to 80 %U-235 content in the fuel assembly is 350 g. In future the enrichment will be changed to 36 U-235.

Fuel assemblies are placed in the pressurised channels. Each channel is individuallyconnected to the primary cooling circuit.

The main moderating element in the core is water, which also provides cooling of fuelchannels and core materials. Its volumetric fractions in the core is only 20 %, but itscontributions to neutron slowing down is 70 .

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The other moderating materials is beryllium, constituting the matrix which fill up thespace between the fuel channels. The reflector is assembled of graphite blocks canned inaluminiurn and cooled by water flowing in the separate pool cooling circuit.

The control rod units divided into two section, connected with disconnectable joints.The upper section are supported on the upper support plate above the water level and containdrive mechanism, the lower sections, containing active portions of the rods as well asconnections and control rod followers, move inside the tubes placed in 28 mm dia. holes inthe beryllium matrix blocks. The control rods are cooled with pool water flowing down thecore along the gaps in the control rod channel.

3. REACTOR CHARACTERISTIC

The basic characteristics data for the MARIA reactor are presented on the verticalcross section of reactor pool, Fig. 1, on the core and reflector view., Fig. 2 on the crosssection of the fuel assembly, Fig. 3 on the core layout, Fig. 4 and in Table I.

The reactor core power distribution and reactor MARIA parameters of water coolingthe fuel channels are presented in Appendix .

3.1. Neutron flux densities in the channels for irradiation.

In Fig. 4 the 20 - fuel channels' reactor core configuration has been shown and for thiscase the following densities of thermal neutrons' fluxes in the irradiation channels have beendemonstrated in Table 11.

3.2. Thermal neutron flux densities at horizontal channels' outlets.

In accordance with Fig. I and Fig. 2 the MARIA reactor has got six horizontalchannels for neutrons beams output from the reactor core.

The thermal neutron flux densities at the horizontal channels outlets are within therange of 3 - 8109 [n/CM2 S].

3.3. Reactor operation cycles.

Depending on the radioisotopes production programme the reactor can be operated inI 0 hr, 120 hr or 264 hr cycles.

Due to the need of the apparatus maintenance, periodic robes and checks as well arepairs, there are envisaged appropriate breaks in the reactor operation.

The reactor operation schedule for 1998 is presented in Appendix 2.

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4. REPORT ON OPERATION OF THE MARIA RESEARCH REACTOR IN 1997.

The Maria research reactor used at the Institute of Atomic Energy in 1997 wasoperated 3856 hours on power of about 20 MWth.

The reactor operation was aimed for:- irradiation of target materials for the Isotope Research and Development Centre and the

Institute of Chemistry and Nuclear Technique,- usage of neutron beams for physics research.

There have been irradiation 200 cans with sulphur, 74 cans with TeO2, 32 cans withSM203 as well as iridium, ytterbium, potassium bromide, potassium chloride, alkaline andbiological substances. The received specific activities of isotopes, in particular the Ir-192 650Ci/g) have proved the large possibilities of Maria reactor for radioisotope production.

The four out of the six reactor neutron beams were being used:H-4 - materials testing by means of the neutron scattering spectrometer,H-5 - identification of atomic magnetic moment values by usage of polarised neutron

spectrometer,H-6 - research of dynamics of crystalline and magnetic lattice by means of triaxial neutron

spectrometer,H-7 - measurements of thermal neutron current.

Nuclear fuel of the MR-6 type (80 enrichment of U-235) has been tested whichallowed to increase its bum-up to 45 and simultaneously more effective its usage in thereactor.

During the reactor operation the minimal releases of radioactive substances to theqct.T 1013atmosphere occurred e.g., emission of noble p"es (mainly Ar-41) was equal to 9,3. Bq

(i.e., about 10 % of the limit value), emission of iodine - 4,5. 107 Bq (i.e., I of the limitvalue).

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TABLE IGeneral characteristics of MARIA reactor

Nominal power 30 MW

Maximum thermal neutron flux:

in fuel 2,5. El n/m 2sec

in beryllium 4,5. El n/m 2sec

Moderator water and beryllium

Reflector graphite (blocks in Al. Cans) and water

Fuel element:

material U-Al. Alloy clad in Al.

enrichment 80% U-235

shape six concentric tubes

overall dimensions I 0 cm height

Primary fuel cooling system:

type of fuel channel field tube

pressure range 1,8 MPa

temperature, core inlet (outlet) water flow

rate: 40 90) C

per channel 30m 3/h

total 600+700 m 3/h

Primary pool cooling system:

pressure atmospheric

temperature:

at core matrix inlet 400C

at core matrix outlet 450C

water flow rate 1400 in 3/h

Secondary cooling system

pressure 0,25 MPa

temperature:

inlet 340C

outlet 260C

flow rate 2600 in 3/h

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TABLE 1

Characteristics of vertical channels for isotope production

Core Diameter Thermal neutronco-ordinate [mm] flux In/cm 2SI

F-VB 28 2,2 E14

KNIA 28 2,6 E14

1-1-VA 28 3,6 E14

G-VB 28 3,6 E14

F-VIB 28 3,6 E14

1-1-VB 28 4,0 E14

G-VIB 28 4,5 E14

E-VII 28 1,4 E14

11-8 28 3,4 E14

h-8 28 3,2 E14

I-V/ +8 18 2,6 31-10 4

K-VIIIA 28 1,6 E14

II-XII 28 1,4 E13

I-xi 28 4,0 E13

H-M 28 5,0 E13

I-XIII 28 1,0 El 3

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1 2 3 4

....... ...... ... . . ... . .. ... ... ... ..

.. ............................................................ ..............

.... ..................... .......... .. ... ................................ ............F F

9 6

10

H3, H - 135 cmH - 1 cmH4, H5, H -95 ,

................ ....... ..................... . .. . ......... :......... ..... .......... . ...... .... ........ ... ... .. .. . .. ... .... ... ..... ................ .. ... .. ............................................................. ...... .. ...... ...... ... ...... ..... ... ... .... ......... ............

I J1 12f 1 3 14

1. control rod drive mechanism 8. beam tube shutter2 mounting plate 9. fuel channel3. ionization chain ber channel I0. ionization chambers shield4. ionization chamber drive mechanism I 1. core and support structure5. fuel and loop channels support plate 12. corc and retlector support plants6 ate support consol 13. reflector blocks7. 0 sutter drive mechanism 14. beam tube compensatorjoint

Fig. 1. Vertical cross-section of the MARIA reactor

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2 3 4 5

H7 H8

0 D 0

0 0 D 0

0 3

0

0 0 0 0 0

0 0 0 0 0 77� 01010- 0

0 ox 0 01 I 010 0 0 00 0 0 0 01 0 1 0 1 L0 0 0 0 0 0 F 0 0 0 0 0 5 0

- 7-0 0 0 0 0 0 0 H5

0 01 0 0 00 0 a 00

0 0 00 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0101F.-77 7 1 tJ

H4 0 OV10101010101 00 0 PI 0 1 0 10 10 1 I 77 +

0101010101010 00 0

H3 00 0 0 0 0

0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0

6

core and rflector support plants 5. graphit rflector block2 multiplegraphiteblock 6. beryllium block3- reflector support structure 7. ionization chambers shield4. bearn tube compensatorjoint

Fig. 2 Horizontal cross-section of the MARIA reactor

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Reactor MARIA core layout

4 5 6 7 8 9 10I

0 0 L(nk

0 K

PAR

3I

h

H

9

G

f

0 F

e

0 0 E

d rV VI VH Vill ix x

control safety automabc irradabonrod rod Cor,%trol rod channels

2) 0 (2) & (1) (D030 025 015 hycraLlic

transport

fuel mov ble graphte SYSternchannN $jet Zmel plug Ad

4 beryllumplag

Fig. 3 Reactor MARIA core layout

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1. fuel tubes2. holder3. distance fins4� cladding5. fuel

052

075

-Fig 4 Fuel assembly

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Appendix Data. -,.Z. U4. I'Jb Godz.: 11:00 Nr.

SU 'D I. L: m 3 II III = 'Jb.':),C SP = I3.bjUMW cmM APMW

IJ. m3/h 14.1 m3/hl Prz e I wk (.). (-) (C b 4. � " U lemperatura

sunka s�inka Ro�nica temp(I )o MW �jw mo�

I 1 m I h 'L26 4 m3/h '28 . 9 m:3/h3 J. 4 " L PJ. i� 1 C /6.4 "U

spinka ou 19.4 o mw (./16 MW o.641 MW

2 9. 1 m3lh '28. m3/h 29.9 m3/h '28.4 m3/h 20.3 m3lh lG1 = b49.9 m3/hi 13-3 7 0 C 9 L�' 4 OC 7 5 7(I C 74 U C (c 2G1 = 1488.7 m31h

A-1 8 OC 3b 4 " C O 8o C 17. 6 ) C s�i r, ka 1161 = 2490.5 m6/h1). 830 MW 1.164 MW 0.640 PIW Q. 1, b 1 M W o. 0c) MW

-`9. -� m3/h i�'J. U m3lh c9. bm,3/h 27, 9 m,3/hh B /. OU 138 J o c '35 4'IC E, 7 OU

30. 0 "L 41. 3 1 U U. to 11 C C. 13 1) cI. oc-o m I MW 293 mW 0. 2 7MW

m�/h .8 U m3/h 28.1 m3/hLZ9. ZZ m3/h '""J. L 1-) - m3/h delta p m 11 U13 b. , �o C Iij I o ',3. Q CU 81 1 'IC 74.b QC 1)

a U t�v. (C 11.1 QC spinka941 MW I b MW IJ131 mw U. b 72 MW 0. uoo PIN Is fI 1. '2c"A MW

k::14. m.S/h 8 m,3/h i� h

I I.J. b U lb. Ck a A. L; I Li. -C

Q. mw U. QI mw Q. 6 QO MW

1,,,. 1m3/he 54.6 QC

s inka0. Ccw) MW

.7 8 13

L) a t a 4. YJ 0 Lmiana; Go d z . 1:00 W.

SU t / 1. UmV h I I 5 . b o C SP = 13.478MW CMM MW...........

19. m3/h 14.0 m3lh Przepl vik u. 'IC 53.8 "c 'Fe m Perat ura

Spinka spinka Noznica tempMW Wo mw mo�

Ic"'. 0 m 3 II -8 4 m3lh �28 9m 3/ h3J. - 'IL 16.5 11 L 75 7 (CWnka -2 U " L 9. �, oc

MW /14 MW V 64 MW

i� m3/h '�B. 8 m3/h 29.9 m3/h --O. m3/h 20 3 m3lh IGI = 55 6. O m 3 hi 83.1 1 U 91. -7 'IC 15.1 ou 13 O tA. b 0 C 2`6 = 4 4. 8 m h3.L - ocEG I n U O IL 18.6 oc 16. Ij oc spinka 1161 = --"4-19.'j m3lh

U.1386 MW 1.158 MW 0.633 MW 0.534 MW 0.000 mw

.c,9 1 M3111 i2 V. m3lh 5 m31h 28. O m3lhII 6 . L O C 9B.3 O C 94.7 'IC 62 1 . oc

ISQ. / 11 U 41.8 1) U 38. 1) C 6. --- oc1.(19 MW 1. j82 mw 1. i�Bb MW U. 96 mw

c_:f. m3/h L:9. m3/h L8. m3lh ;:�8 7 m3/h I 5. m delta p 1.99 m H 134. LI 11 L; 7 8 QC I ,C 2Lai. 'IC I " L; 30.--1 'IC 3 'IC k

0. also) PIW 1. i2i�4 MW 9131 MW U. b67 MW (.0 mw I, 1.221 w

14.'/ mj/h L8.8 m i29.1 m3/ht b4. E I, U ./ Li. O QL�/hj 4.b o U

spinka --,I 'IC 18.1 (ICMW U. /Ob MW 0. 00 mw

IL.1 m3/he 54.0 'IC

spinka0. mw

b 8 13

326 -

Appendix 2

Schedule of reactor MARIA operation in 1998Data of actualization 16.03.98

Mo. Tu ';We; Th; Fr Mo:: Tu': Wel Th: Fr Mor Tu W6. Th Fr Mo Tu: We. Th: Fr Mo:: Tu'We' Th Fr Mo Tu

6 7 8 9 :13 14:15: 9 2 2 2 6 ::2 7 ':2 :2 9 ::3 January

;53 :4 :10 :11:12 :13 17 :18 ::19 ::2 t4 25 :26 ;2 7February IV I

V ...........4 5 6 :10 A I :`1 2 :I 3 6 17 A 8 :19 :2 7 3,0 �31

March Villt

8 9 :1 o : 4 :1 5 :16 ;: 7 0 7 1 22 �2 3 2 4 �2 8 �2 9 3April xi: : V------ -----

I A 2 'I 3 :14 :1 5 �1,8 19 :2 :2 1 '2 6 2 7 :2:8 .1 2 2�5 :2 9q aMay :7 iv:

;XV

-1 2 :3 14 :5 :10 :11 A 6 7 ::I ::I 9 3 4 ::2 � 6 9 !3 June : i XVIa �. I I:

-------------a

I 2 3 8 9 'I :14 1 5 6 17 :. 0 .21 :2 2 i2 3 !2 4 �,7 2 :29 30::31July F- I XVI I x I .,.X 31-

t7=;4 A I: 2A 3 ::I 4 :1 8 . 9 :2 :2 1 :2 :2 ::2 7 :2

X ;IIAugust X.

September .1 5 C17 1 8 1 2 2 :2 3 :2 4 :2 -8 2 9 �30

2 2 2 3 '2

2A 3:14:1 Z6: o28::29:3October

- - - -- - - --- - -- - - - -- - -- - - -- -- - - - --- -- - -- -

.2 3 ;4 ::5 :6 1 2 17 18 �9 RO 24 5 2 6 �7November�Xvi.:

-I m2 3 ::4 8 :9 ::I � I I 5 ::I 6 7 ;,I 22 73 24 .25 .29 .30 �3 1December x., XXXI

Operation

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