N T R

T U D

ASSOCIATION S.C.K/C.E.N. - BELGONUCLEA RE

L' ANNUAL PROGRESS REPORT 1973

n a i

GAS PURIFICATION PROJECT

N U C L

J. BROOTHAERTS, J CLAE3, 0. COLLARD, W 0OOWCN8

R. HARNIE, P. HEYLEN, J. VAEMN, L. »AfT»LE

H DE 0EUKELAER, G. DUBOIS, R. QLIBERT, j . METTREZ, A. ZAHLEN

BLO 502

144, tv irai» E. FUfky, BRUXEUI» 4 (BELGIQUE)

I, Plttkyfcu* 144, BRUfOL 4 (BtLOU)

J. BR001HACRTS, J CLAES. G COLLARO. W GOOSSENS. R HARNIE. P HEYLEN. J VAESEN L BAETSLE R DE BEUKELAER' , « . DUBOIS*. R GL IBERT ' . J M E S T R E Z V A ZAHLEN* 9LG 502 duni 1975)

A N N U A L PROGRESS REPORT 1973 GAS PURIFICATION PROJECT

ASSOCIATION S.C.K./C.E.N. - BN

Samenvatting Een overzicht van de konceptuele en eksperi"^niele stud'«jj over vangst en retentiesys-tnmen voor nukleaireafgassen wordt gegeven. Sorptietechmeken voor p d i u m en krypton en de kata-tytische oxyuatie van waterstof als simulant voor t r i t ium wordon onderzocht op laboratoriumschaal. Een proefopstelling van 25 m h'1 voor het uittesten van de verschillende eenheidshappen van gasret niging bij opwerking van LMFBR splijtstoffen werd opgebouwd. Als eerste faze in de studies werden de prestaties van wastechnieken voor i j verwijdering bepaald.

De verdere kondttionering van de gassen en de toepassing van de kryodestillatietechnieken voor kryp-tonvangst werd voorbereid. \ 'oor de afgassen van LWR reekforen wore"» een Xe vervalbed bestu­deerd

•BELGONUCLEAIRE

.1 BHÜOTHAERTS. J CLAES. G COLLARD.W GOOSSENS, R. HARNIE. P H E Y L E N . J VAESEN L BAETSLE R DE BEUKELAER". G DUBOIS ' , R G L I B E R T ' . J rvIESTREZ'. A. Z A H L E N * BIG 60? Iiuni 19 '5 I

ANNUAL PROGRESS REPORT 1973 GAS PURIFICATION PROJECT

ASSOCIATION S.C.K./C.E.N. • BN

Pésurrté Le rapport présenie un résumé des résultats des études expérimentales et conceptuelles de systèmes de purification de gaz d'usines de retraitement et de réacteurs. L adsorption d'iode sur tami moléculaires, l'adsorpi-on â Iwsse température de gaz nobles sur charbon actif et l 'oxydation catalyti-«lue de tr i t ium, simulé par de l'hydrogène ont été étuoiées à l'échelle du laboratoire. Une installation pilote pouvant trait**- 2b m' h de gaz a été construite. Les résultats expérimentaux de la première phased» programme d'étu. .concernant l'arrêt de l'iode par lavage caustique des gaz sont présentés. Une extension ultérieure du circuit a été préparée qui comprend le conditionnement des gaz en vue de la capture du krypion par distillation cryogénique.

Sont également mentionnés les résultats expérimentaux de l'étude de lits de rétention de xénon.

•BELGONUCLEAIRE

.! BHOOTHAERTÜ ,l CLAES G C O L I A R D , W GOOSSENS, R HARNIE, P H E Y L E N . J VAESEN L BAETSLE R DE BEUKELAER' , G DUBOIS ' , R G L I 3 E R T ' , J MÊSTREZ*. A, Z A H L E N ' BLG 502 (jum 1975)

ANNUAL PROGRESS REPORT 1973 GAS PURIFICATION PROJECT

ASSOCIATION S.C.K./C E N . - BN

Summiry Conceptual and experimenlal studies on LMFBR reprocessing and reactor off-gas purifica­tion systems are summarized. Iodine sorption on zeolites, low-temperature adsorption of noble gases on charcoal and catalytic oxidation of hydrogen, simulating tr i t ium, are being studied in laboratory setups A pilot loop wi th 25 m h throughput has been constructed Results are quoted from the first phase of the iodine removal programme by scrubbing systems. Further extension of the te*t loop, comprising of f-gases conditioning prior to removal of krypton in acryodisti l lat ion unit, has been pre-

I pared.

Delay-bed studies on Xe exfact ion from LWR off gases are reported.

•BELGONUCLEAIRE

ASSOCIATION S.C.K./C.E.N. - BELGONUCLEAIRE

ANNUAL PROGRESS REPORT 1973

GAS PURIFICATION PROJECT

J. BROOrHAERTS, J. CLAES, G. COLLARD. W. GOOSfcENS

R. HARNIE. P. HEYLEN, J. VAESEN, L. BAETSLE

R. DE BEUKELAER. G. DUBOIS, R. GLIBERT, J. MESTREZ, A. ZAHLEN

BLG502

CONTENTS

INTRODUCTION 1

TREATMENT OF OFF-GASES FROM REPIOCESSING FAST REACTOR FUELS 1

2.1. Conceptual studies 1

2.2. Test loop for iodine trapping methods 2

2.3. Iodine adsorption studies 5

2.4. Removal of tritium from dry head-end off-gases 7

2.5. Noble gases recovery 7

REACTOR OFF-GAS 9

REFERENCES 10

1. INTRODUCTION

Th« leauirscents of volatile fission product containment increase with the progressing

development of nuclear energy production.

Higher activities of tritium, iodine and noble gase^ are generated iii the fuel ûue

to increasing ourn up and specific power, and, specifically for fast reactor fuels,

as a result of tne considerable shortening cf the post-irradiation decay times which

arc crojectsc. Concentration of multiple reactor ur.its in energy parks and size

enlargement c* the reprocessing plants,on the othsr hand, will restrict tne possi-

bilities of releasa at the stack Pecause of local atmospheric dilution limitations.

'is Jt-clop~er,t of the required gas purification technology is consequently of pri­

mary importance -for minimizing the environmental impact of the nuclear energy

-•••r;a'isio'. '-•a association S.C.K./C.E.N.-BN has therefore projected a long-range

crorr-if" :- w'::- ai. s at the development of' high efficiency fission gas retention

bjï*^, 'i' off-gases of fast reactor fuel reprocessing plants and nuclear power

St'iMc' -,.

'"'•- *c". iowi-.g jcjectivss neve teen stipulated :

- " •- oo :-.pr. iù-i J' tne required gas purification system for the reprocessing of

,.'r- " •-.•; v.itr scaling times of 150 days or more ;

• .•-•".••vit: •iti.,'-, of efficient removal of 3H [DF > 102) 85Kr (DF > 102) and

' 5 ,I i. r -• 106'. ir a composite gas purification system for reprocessing of shcrt-

. o, Lij *-izt. r-actor fuel ;

- •-"-•! ,0f-.•£.; loprent of reliable processes for the retention and disposal of '^Xe ancj i~"-r at "clear power stations.

2. TREATMENT OF OFF-GASES IN REPROCESSING FAST REACTOR FUELS

i-jrlr»- i\\k'. past year the main efforts have been devoted to the following items :

'j-'.:Bpt!.d. c-tudies directed toward tne establishment of flow sheets of off-gas

' i r;.-itrtTit for the reprocessing of SNR f'jel ;

- f-.c construction and preliminary operation of the test loop for iodine trapping

met,hó:Jo ;

- adsorption studies with commercial iodine sorbents.

2.1. Conceptual studies [l] [2]

A conceptual study ^a* allowed the definition of the problems of gas purificatiar:

connected with the adaptation of new typBS of h'-sad-ends In the reprocessing cycle

of ohort-cooled fast breeder fuel. The3e head-ends have as their main function the

2,

complete release of the fission gases contained in the fuel, namely tritium, noble

gases, iodine.

Two methods have been investigated for the disaggregation of the fuel ; by voloxida-

tiLsn and by molten salts. The processes considered being at the lab-scale, the

proposals of the two schemes (Fig, 1 and 2) give only the nature of the gas to be

handled. Some gas processes and t^eir estimated performances, connected with the

different steps of the two proposed schemes, are listed.

All this information should lead to a oetter choice of the type of head-end and a

better understanding of the gas treatment systems to be studied.

On the other hand the study of capacity increase of a "thermal" fuel reprocessing

plant and, consequently, the updating of the existing off-gas circuit, has led to a

better view of the gas purification problems. Among these must be noted the denitra-

tion of the gaseous effluents land its relation with efficiency of iodine arid active

aerosols removal) and the importance of the choice of the trapping technique on the

waste volume produced.

2.2. Test loop for iodine trapping methods

The general purpose test loop "GASTC'M" with a throughput capacity of 25 m h , has

been erected [3J (Fig, 3), During the first phase of operation it will be used for

testing the most promising methods of iodine removal on a semi-pilot scale. Units

for trapping interfering impurities will be added gradually in order to constitute

a complete off-gas treatment system which allows the application af lew-temperature

techniques for- noble gas retention.

During the past year the construction of this installation, comprising the con­

tainment, ventilation, shielding, and WAS te evacuation provisions and the distribu­

tion manifold for carrier- and contaminant gases, has been completed. Reception

and working tests of the wst section of the loop, comprising trie dissolver moei'-up,

condencors, venturi elector sen fiber; brink demister and iodine generator have been

performed [l] [5].

The set-up allows the simulation of the multicomponent gas mixtures, which are to

be expected in gaseous effluents from a fast reactor fuel reprocefsing plant.

These mixtures can be fed into the chemical (Venturi ejector scrubber) and physical

(Brink demister) separation units, ..sing nitrogen carrier gas, at f-low rates varying bt

tween 5 and 35 Nm3h_1.

Loading with iodine is performed at a nominal rate of 2.5 g I 2h_ 1 ; the iodine is

generated in a scaied-up iodine generator developed earlie" for the determination

of break-through curves in a 1 m3hr'- loop.

After check-up of -he control anc measuring equipment, a number of cold -uns has

been performed in order to define the operating characteristics of the different-

units of the loop [6i .

2.2.*. Removal of iodine in aqueous systems

The first experimental canpsign in GASTON was cevoted to the study of the efficiency

of the venturi scrubber (with a 1G % K.OH scrub solution], of a primary impaction

demister ana of the brink demister as Final element of I2 removal from N2-X2

mixtures. The verturi s-rubber was operated with liquid flow rates between 300 and

750 i ,n~', whereas the total gas flow varied oetween 7.2 and 34 ?Jfn3h~' . [7]

Oepgrr;ing joon the I? ".ass flow rate, typical results for the iodine trapping

b + f i .j.-or.oy of the systems inve?tigoted are :

- r,,:' tr;-; :ji<i::jy\ .prutser : > 9?-39.S

- --T : he -/3nturi = crubr.vi'primary demister : > 99-99.C

- 'r," the ventu:! icrub; ;"pr^arybrir.K dw-ister : > 99.9

j-jan c : tativf: uv/aluation c.f tnc results as a function of the operating parameters

û[ ce f red t.i bc ui f t L •.._. i t, ace tc liquid particle entraintnent from the scrub solution

:-• t-i- gas stream. Nevertheless, it became clear that the rather high liquid-to­

gas molar ratios UC1* - 'Ü61, at which the vsn'uri scrubber was operated, ensured

almost ..C'Str-rit and high I? trapping efficiencies even for extreme variation of

scr^b solution a-d l? r«af-s fin* ratç; (f;;g. 4] operating conditions.

In a .-econd pnase nf the opération of :'îA3iON, for testing wet purification systems

for I;: - trapping, the venturi. scrubber was replaced by a gas atomizing aaroscl gene­

rator. The latter produces diluted K.QH liquid particles of 0.5 u.n diameter at flow

rates between 10 and 40 g h - 1. rhes« particles were entrained with the main gas

stream as to capture part of the gaseous icpina. For the same gas and Ij> flow rates

as above, the concentration of the residual gaseous 1^ before the final brinK

demister, showed efficiencies of this system between 32 and 93.9 %, depending u'jon

KOH rrolarity and solution flo* rate. The results obtained with this aerosol system

were analysed as a function of the molar I? concentration, K.OH normality, aerosol

concentration and contact time, yielding the plot shown by Fig. 5, which demonstrates

tnat, even at stoichiometric fTJh/I2 conditions, 7ü \ of gaseous iodine Is removed.

4.

2.2.2. Extension of the test loop [a] [a]

In order to increase the experimental possibilities of the GASTON loop., a study

of the extension of the wet section has been performed. Two goals were aimed at for

a new scrub installation :

- behaviour of iodine in gaseous effluents with high content of nitrous vapours ;

~ study of „he trapping of I-compounds by aqueous scrubbing.

To determine the size of this scrub column, an evaluation of the composition of the

main compounds of the gaseous waste from a reprocessing plant has been made. The

Corresponding inlet flaw rates for the GASTON loop are the following :

nitrous vapours : 8.5 m3h~'

02 : 5.3 m3h"'

N3 :21.2 m V 1

'I compounds) trace

total flow 35 m3h_1

If an absorption efficiency of the nitrous vapours of 9C % is assumed (as in in­

dustrial conditions), the outlet flow is 25 m^h*1.

Qesign studies far two types of column (trays and packing) have shown the difficulty

of putting this new wash installation in the existing ncod. For the above absorption

conditions, the kinetics of nitrous vapours removal are led by the oxidation of HO to

M02 -'n gaseous phase which, involves a long residence time of th'e gas in the column.

In this case, the trays column is the best choice. However, the preliminary informa­

tion obtained concerning the trapping mechanism of iodine by scrubbing (main reaction

ir liquid phase) and the fact that the packed column is better adapted to experir«nta

work, have led to the choice of a packed column.

The available space in the existing hoods, toget.her with a market research led to the

following specification for this scrub column :

diameter : 150 mm

packing height : 180C mm

An experimental programme has been written which considers the choice of this column

and the information to be collected on gas purification by wet methods. This

programme concerns both scrubbers (venturi and packed column) and includes four

working conditions for the new scrubbers.

5.

•"lo'w rate

ption

ption

ptinn

ption

i

-

3

4

2-

1.6

2;

3. h

rr n

i _1

r.3|-i

T>3r--i

Inlet composition Scrub solution

3.5 % NO NaOH

i

i

25 \ NO X

5-1Q % NO y

3.5 * NO X

HN03 5 N

HNO3 5 H

HNO3 16 "1

Ciodex process)

h rem fhese operational conditions, the different elements of the raw scrub section

have r.ee<-' analysed and specified (cooler, pump, waste, buffer tannsl.

The 'îQ-nscticn tu the GASTUM loop has been studied and the process flaw sheet, in-

cljdino tnp instrumentation, has been drawn.

lid IÖVJ;

COl^r-- i-

t.,is wet section has been started and the mounting of th

t, e first nor, the of 1974.

2.3. IuditK adsorption studies

< . i. *. r r" ijr?to:'y werK

1' . is>. jf t h-v jtj-j-, -," th=3 re'oval of 1 3 îI labelled organic iodine compounds, a

",*- - j . I.:.,- ?:--^:ic;t njs cc-en -jevyloped which is based en diffusion through a

' p:ï.:jrv *•:.-• . on -vcted to a temperature-controlled CH3I vessel in which complete

iso;j:'i.. :./-.iang:: r.a& teen acr.ievea. Although this system gives good results during

s-o.'t :;p r-it.io,' tim-js, it is r, c«~,sary ta control the operating conditior.s very

Ij-Ji''t- ad'-.Trpt: ori '.ft-, the-. : nvestigatfcd [_1 QJ in a silver-coated copper tube (dia-

->n'-:r i "-m, ;e:\K',h 1 :r, a'1"! IS T. The removal efficiency was 99.99 \ ; scanning

•• "tidïur^-onts indicated that ta9 distribution of '3_lI was exponential.

"ht- ort-iSSure drop characteristics cf sorbent beds were determined [_11J in a column

oT' ..!.'"' mm diameter.

A literature rsviow and evaluation study of sorbents far applications in humid NO

atmospheres was made |_12J.

2.3.2. Adsorption isotherms for iodine on impregnated sorbents

Impregnated /eoliths .have been considered for high efficiency trapping of iodine and

its compounds, in tru-i presence of disturbing agents such as water vapour and nitron.^

j'ido.:-. lhe iodine capacity of copper, lead and silver zeolites was measured by

tr ipplng ^ M trac*! iodine on a shallow bed of sorbent iri a well-type scintilla-

':.'! •-.rystal. It wa'.. found that the capacity of these impregnated zeolites Is smaller

ttmn tha capacity of tha rwiaprajnatad ona*. Sllvwr is tl» baat ijapratnant. laading

to a capacity of silvar zoolitas of 5 wt, t which was net influençai by a tamper-

atura change from 30 to 1Q0"C, tha lattar taa*>er«tur« balrtg of interaat for ob­

taining wary high iodine ratantion efficiencies.

Based on these promising results for silver Zaolltas. a parametric study was started

on the silver impregnation of large samples of 500 g molecular sieves Union-Carbide

type 13-X using the through-flow column investigated last year. The best results

were ottained with a small excess (10 %} of a molar solution of silver nitrate giving

a 92 I cation exchange efficiency for the impregnation pTJcess.

2.3.3. Dynamic adsorption of iodine on itolecular sieves

Based on capacity measurements or. various sorbents. Union Carbide 13-X molecular

sieves were selected for parametric investigation of the dynamic behaviour of sor­

bents for trapping iodine from dry gases. From measurements of break-through curves

performed in the 1 m*h loop, the following conclusions could be drawn :

- the residual sorbent capacity influences the kinetics according to a second order

law, as was deduced earlier from static shallow bed measurements i

- the sorbent capacity is independent of the inlet iodine concentration in tht

range 70 to 400 mg l2m~^2-

- regeneration at 2Q0°C has no subsequent effect on the dynamical behaviour of the

sorbent : after five adsorption-desorption cycles, each involving more than 200 h

at 200QC, neither the capacity nor the shape of the brean.-through curve are

significantly affected.

The kinetics of iodine adsorption on 13-X-sorbent follows a mathematical model

which allows the prediction of the outlet iodine concentration ^s a function of gas

flow rate and bed height. Fig. 6 show9 the fitting of experimental data to the

mathematical model.

The effect of humidity in the carrier gas Is disastrous for the iodine retention on

this type of molecular sieve : a bed saturated with iodine instantaneously releases

the iodine as BOOH as water vapour is present in the carrier gas. Similarly, mole­

cular sieves (such as Norton Zeolon 900 and CECA HK 20), adsorb only 0.5 wt. \ when

they have been previously saturated with humidity. Consequently, the sorption of

iodine from a humid gas on these molecular sieves requires either predrying of the

humid carrier gas or metallic impregnation of thB molecular sieve.

With a IIL' 13-X aorbent, predrying and adsorption can possibly be combined in one

column, tha iodine capered on the sorbent is displaced by water without affecting

the initial iodina decontamination factor ae long as the iodine front does not reach

tha bad and.

The behaviour of organic iodine compounds und*r dynamic opvrating conditions re­

mains to be determined.

2.4. Rcaoval of tri tit» f re* dry b**d-ei«l off-g*i««

If complete release of tritium from the fuel can be c'ltadrnH in the dry head-end

processes under development, the proposed treatanertt for removal and disposal of the

nuclide consists of catalytic oxidation on noble metals or metal oxides and subse­

quent adsorption of tritiated water on molecular sieves-

The catalytic oxidation of tritium and in-situ retention of water on the substrate

of the CuO catalyst is investigated in a test loop of S m'h'1 where tritium is si­

mulated by hydrogen at a maximum flow rate of 3 I h~*. The first run indicated

the necessity for strict control of the gas prehaater and the catalytic bed and the

need for discrete chromatographic gas analysis. A 5 t bed of Cat-Chem C54-S

catalyst werking for 1 SO h at 160°C and using 5 m3h_1 carrier gas, showed a hydrogen

decontamination factor greater than 250.

2.5. Noble gases recovery

8ELG0NUCLEAIRE has updated the scheme and the working conditions of a pilot plant

for the recovery of noble gases from gaseous wastes. Inquiry has been made Into the

composition of the gaseous effluents to be handled in reprocessing plants and light

water power stations (PWR and BWR). The results of this inquiry have allowed the

definition of the optimum service conditions of a pilot plant and a range of saluas

in which the performances of the pilot must be investigated (_13J .

The inlet composition of the eff-gaa was :

N2

°2 Kr

Xe

ao i

20 \

1 SO vpm

1500 vpm

Thp performance reauired was 99 % recovery of Kr and Xe, with a concentration

factor of 10* for the noble gases recovered.

2.S.1. Adsorption of noble gases on charcoal

The static adsorption capacity of activated carbons for Kr and Xe has been

determined at different temperatures L 1 4]* The adsorption isotherme of Kr on various

activated carbons (RBL-3, Norit Extra, flerch Carbon and CECA NC 30) with specific

surface areas ranging from 1300 to 2000 irrg"1, were found to follow Freundlich's

law in the temperature range -198 to 25eC. The adsorption of Xe on the same cerbens

has bsen studied at room temperature (for delay bed operation) and at »78°C Cfor chro

matographicel separation from Kr). The Xe isotherms derived showed an uncertain

».

dependence on partial pressure, which can te approximate** by • l i n w relationship.

During adsorption tests of Xa and Rr In • loop constructed to perform dynamic tuts

en chromatographic separation of Xa and Kr at -76*C, St was found that X* »*es

absorbed in a rather small part of the bed whereas the Kr was spread over the whole

bed.

An evaluation was made of a low temperature adsorption system for th« removal of

*5Kr from reprocessing off-gases, [lb]. It followed from the conceptual study that,

coopered to cryogenic distillation, this system is more complicated t the former

was consequently chosen for construction and study at the S.C.K./C.E.N.

2.5.2. Cryogenic distillation

Concerning the cryodistillotion unit retained as a pilot plant (Fig, 7), the entire

scheme, including instrumentation, has been reviewed.

The preliminery design of each equipment has begun, and two types of low temperature

heat exchanger have been studied and compared', packed regenerators and plate-?in

heat Rxchangers. The latter are nowadays widely used in large cryogenic gas

separation plants and they offer several advantages :

- high performance i

- no contamination of purified gas by the incoming stream t

- simpler set-up (no valves for flow inversion).

However, this last advantage is lost whan the incoming gas contains impurities such

as H2D, CO2. ^tc. having relatively high condensation and freezing temperatures »

in this case, plate-fin exchangers must be operated in reversing mode.

In addition, their length must bv sufficiently great to limit heat leakage by

axial conduction, which leads, for small units to on awkward design. The regenerators

therefore seem to be preferable for the pilot plant.

For the sizing and the choice of the absorption and distillation columns, some Infor­

mation has been collected end computation done. Theoretical methods for predictions

of phase equilibria have been used for Kr-Xe-Dj-^ systems. The existing methods

have not given better results than Reoult's law [l6j [l7J ,

The advantages and disadvantages of packed and tray-columns have been discussed for

the pilot plant. A packed column has been chosen because it gives greater expérimental

possibilities than trays 1 the height and type of packing oan be changed. After a

literature review and a market inquiry small metallic mesh rings are considered the

best choice.

9.

Ta apeed ÜP th« installation of thi» pilot plant, a global offer for *ba cryodi»tina­

tion unit has been written and eant to potential manufacturers.

This preliminary specification [is] gives the conceptual design, the charcqtaristics

of the effluent to be processed fsee above. Inlet Composition of the Off-gas)»

the requirements concerning operation and the performances demanded.

3. REACTOS OFF-GAS [l9J

The study of an alternative to the conventional decay tanKs to process the off-gas

from PtaR has been pursued. The flow sheet of an installation baaed on delay beds has

been defined (Fig. 8), and gas- composition and flow rate have been estimated for a

1000 HWe PWE. The gas decontamination factor retained for the 133Xs is 103.

Two types of operation of the delay line have been proposed and studied : delay beds

working at atmospheric pressure in the first case, at 5 ata in tlr? second one. The

sizing and the preliminary design of equipment corresponding to these two working

conditions have been carried out, namely buffer tanKo, dryer unit and delay beds.

Increase of pressure allows an increase in the quantity of gaseous waste processed

with the same gas facility, or a SIZB reduction of the delay beds for the same flow

rate. Nevertheless, the work at pressure requires an accurate regulation of the

pressure and increases the risk of leakage. The final choice between these two

working conditions will be e function of both safety and economical criteria.

Thus the preliminary design of the two off-gas systems based on theoretical data

has to be checked with the help of an experimental programme, For this purpose, a

col ...in of 15 cm diametBr using various lengths of active charcoal has been built at

S.C.K./C.E.N. Mol. The dynamic runs of adsorption will be startGd in the beginning

of next year. In all cases the study has shown that the delay line allowing instan­

taneous handling of contaminated off-gas gives more reliability and safety than the

decay tank system.

For the 8WR, the study of the off-gas system has been startedr Process flow sheets

with different options have been established (Fig. 9). Each flow sheet includes

the recombination of radiolytic H and O2 and a delay line for the lj3Xe. Further

work will be devoted to the analysis of the options, the elaboration of an engineering

flow sheet and the preliminary design of equipment.

10.

UFEUMCSS

[ l ] G. Duboi»

Retraitement des combustib&B rapides - Traitement dea affluant» gazaux

BN Nota 712.4Vl93/ni/097-July 11. 1973

[2] ». Glibert

Définition de tjuslquss problèmes r e l a t i f s ou traitement ÖÖB affluants gazeux

d*ufts u*ina da re t re i* nt de combustible theinique

BN Note 712.44/193A jy 22. 1973

[3] J. Broothaert*. R. Bami e, J Vaceen

Proefopstell ing voor jodiumvangst

SCK/CEN NotB 573/44/l44/JB/mvre/4, March 29. 1873

[4] J . Claes

Experimenteel programma gaszuivering - 1973 j GASTON I 1 Natte behandeling

SCK/CEN Note S73/44/144/JC/lb/4, Fetr. 2, 1973

[5] M- Ponet

lodium generator voor de 25 m3h~^ loop - Modus operandi

BN NotB 712.44/193/n/089, June 26, 1973

[e] A. Zahlen

Etallonnage et essais de réception et de fonctionnement de divers éléments

de la boucle 25 m V 1 ; GASTON

BN Note 712.44/183/n/100, July 27, 1973

[7j J . Claes

Bedrijfsvoeringsresulteten van da proefopstelling GASTON-Joaiumvangst uit

opwarkingsafgassen met natte zuiveringstechnieken

SCK/CÊN Note S74/44/144/JC/pool/62, Febr. 2, 1974

[s] G. Duboi»

Propositions pour une installation de colonnee de lavage (Boucle GASTON -

25 m'h"1)

BN Note 712.44/193/n/101, Aug. 14, 1973

[9] G. Duboi»

P r o p o r t i o n s pour le raccordement d'une i n s t a l l a t i on de levage aqueux à la

boucle GASTON - 25 m V 1

[10] C. Collar*

Adaorption de l'iode eur un tube argenté

SCK/CEN Not» S73/44/144/GC/hm/24, July 10, 1973

11.

[il] G. CoHerd, M. Anoathakriahnaa

Date record of pressure drop measurements for fixed bed of adsorbents

SCIC/CEN Note S73/44/144/GC/jnvm/21» June 12, 1973

{jf] G. Collard

Evaluation d'adsorbants pour la purification de gaz de retraitement

SCK/CEN S73/44/144/GC/mvm/12, March 12, 1973

[l3] R. Glibert

Concentration et récupération des gaz nobles de fission contenus dans des

effluents gazeux. Détermination des conditions opératoire* d'une unité pilota

et schéma de fonctionne»nant

BN Note ?12.44/193/n/107. Sept- 28, 1873

[l4] M. Ananthakrishnan

Removal of noble gas isotopes from radioactive gas streams

SCtt/CEN report R. 2541, June 1973

[Î5] J- Broothaerts

.Krypton vangst door adsorptie op ektiev» kool bij loge temperatuur

SCK/CEN Note S73/44/143/JB/pool/2, Oct. 18, 1973

[16] G. Collard

Etude théorique de la solubilité de Kr dans Na liquide

SCK/CEN Note S73/44/144/GC/IW28

0 3 C. Dubois

Bases expérimentales pour le calcul dss courbes d'équilibre das systèmes

krypton-azote et xénon-azote

3N Note 712.44/193/ni/105, Aug. 28, 1973

jje] J. Mestrez

Unité pilote de séparation et de concentration de Krypton ot de xénon par ab­

sorption et distillation cryogénique

BN Note 712.44/1B3/8/1D6, Oct. 2, 1873

[19] C. Dubois

Traitement des effluents gazeux hydrogénés d'un réacteur PWR (1DOO MWe)

Proposition de schéma général de circulation

BN Note 712.44/l93/n/093, rtay 30, 1373

Soent fuel

jSod'um el imination j

i , .

Dissolution by

HNO3 + HF

N , 0 2 I N O Mt>2

FIG. 1 REPROCESSING OF FAST BREEDER FUEL (SHORT COOLING TIME) OFF GAS TREATMENT

Option : "Disaggregation by Voloxidation"

f

J 1 t j Disaggregation

i voio*.tC t .

ianon

1 N,02

L iO, PuOj dusts

X e K r | T i t r i t i um removal

"1

r _ _ ,^

Optional

Nitrous • • a p o u ' s j ^ j fodtne J Nobip gases | treatment \ \ uedtnenr I " ^ ue f. 'Tt«nt T 1

Storage of h.gb-acTive level i tquid wastes

tquipment veoti idtton

j Concentration of 1 H .gh-active level [ >-qu>d wastes

r r Ceil venti lation

"iNOa-NO-COi (!)

Scrubbing i {water or nitr ic! acid> \

CKidation and water recovery (Sieves, sihcagef)

i r Scrubbing ; (water! !

I N O

. I ,DF iaioo

Scrubbing (rustic) Scrubbing «ni»rcuriL Solution)

n r

N O , 0 2 (I)

Absorption m ruofoear-bon suivants Cryogenic d tsMla fon

ludme OF 1000

J L Nk>t>lc g<ises DF

10 100

Cotci trap Acid scrubbing Men uric scrubbinq Causae scrubbing

- IAg Reactur)

Scrubbing (water)

Mercuric scrubbing , Cracking i N C V C O j I separation !

- Cold trap Ag Zeolite

• Impregnated charcoal

ludine DF 1000

NO„DF 10-100 Iodine OF 10 Iodine DF 25

Soent fuel F I G . 2 R E P R O C E S S I N G O F F A S T B R E E D E R R E A C T O R F U E L ( S H O R T C O O L I N G T I M E ) O F F G A S T R E A T M E N T

O p t i o n : "Disaggregation by mo l ten salts"

Optional

' Concentration of ! high-active

level wastes

Filter

CO > (1)

Stack

L

Cette ventilation S- Stack

•>

• Scrubbing Oxidation Molecular sieves Silicagel

Cold trap Scrubbing (causticl

Iodine DF : 1CT

Absorption in fluorocarbon solvents Cryogenic distillation

Cold trap Scrubbing (caustic or mercuric or acidl (Ag Reactor)

Scrubbing (water J

Scrubbing (mercuric) Cracking N O „ / C 0 3

separation

Cold trap Ag zeolite Impregnated charcoal (Ag Reactor)

Noble gases DF 10 100

Iodine DP : 1000

NOx DF 10- 100

Iodine DF 10 Iodine DF 25

HG 3 res: LOOP roR IOOINE TRAPPING

«JO IN~-

1 > o ; J<

A S'.rubuinç l iqu id

b Venturi urucher

i Üenistc:"

0 üissolver

F Condensor;.

F; Storage of basic solut ion

F. Storage of acid solut ion

i Uaste transport

\. Vacuuj, r.roup

I. Iodine generator

k Condensed l i qu id

0 Charcoal f i l t e r

P f'unfi

I.C. Thermocouple

k Storage of waste solut ion

X Brink deimter V ury section

',Q Gas sampling

SL Liquid sMiplInç,

ICO Column

101 Cooler

102 Recycle vessel

103 Pump

104 A/E Uaste solution storaçe

Ne* connections

New lines

Gas c i r cu i t

Liquid c i r c u i t

Fl

PI

TI

LG

Flow indicator

Pressure indicator

Temperature indicator

Level rauge

DF

103

102

M, i g h ' )

0 0 9 5

0 0 9 6

1920 •

2.900

10 I I I I I f "

10»

I I I 1 I I I I >

1 0 '

T—i—r i ! i i l i i

io-«

H G 4 IODINE TRAPPING IN VFNTURI

SCRUBBER

01 10 10 100

mol.h-' KOH

mol.h"' I ,

FIG. 5 AEROSOL GENERATOR OF VERSUS MOLAR KOH/I, RATIO

FIG b FITTING OF EXPERIMENTAL BREAK-THROUGH CURVES

outlet activity

Gas velocity Ims"1 i

0.28

0.28

007

0.21

Column height (nil

^ * *

Ventilation

+4^Analysls Winmail** Vacuum

Fr*m avtftr tank

Comprtitor

FIG 7 CRYODISTILLATION SCHEME OF THE PILOT INSTALLATION

Add i t i o na 1 t q u i piru. n t

Operation under press*, re

r—1

--'>'.'"»:^4- " < >4 -»- Ventilation

(.t-.> stack*

Pressure diagram

I

1.25 to 8 ata max.

.25 to 8 ata «ax.!

*r

»L *r

6 tu 8 ata •L T

1 ata

Constat! 5 ata d. T

I a i

I : Buffer tank 2A - 21 : Compressors

1 : Filter 4 : Buffer tank

5A - 51 î Compressors 4 : suffer tank

?A - 71 : Coolers 8A - 8s - 8C : Silica-gel _dryers

9A - 9B : Charcoal beds I0A - 10» : Filters

PR : Pressure Recorder TR : Temperature Recorder FR : Flow Recorder

X : Charcoal bsd operating pressure : 5 aca Y : Charcoal bsd operating pressure ' 1 ata

rig. g F M S SU» I ZED WATER REACTOR 1000 MWe

OrF-CAS'TUATWHT CEJIEBAL FLOW-SHEET

Off -gas trom ram c o n d e n s e r "

C a t a l y t i c r ecombina t ion ot r a d i o l v t i i ' R- dr.d

? !£-gas trom

Opt ion I : RECÜMBI.VER t'SINO STEAM DILl'EST

Air d i l u e n t r ecyc led

Air j e t P r e h e a t e r C a t a l y t i c Reco^biner ondenier%

h.,1. j tcy: ieti

to reader

option II : RECOMBINE» L'S £NC A NÜS-COSDESSIK- :...,'.\Cl.V:> DRIEST

Delay of short

heif-life isotopes Of f-gas dry ing

Charcoal adsorption

(delay-bed»)

LUI e lay-pkpe

r&

Dessinant dryer

Charcoal beds Filter

Opt ion !II : CKARC0A1. BEDS r.PEHATlNC AT AMBIENT TEMPERATURE

l£K Cooler Charcoal bods File*-

Re£rigerated vaulc

O p t i o n IV : CHARCOAL BEDS OPERATING AT l.OU TEMPERATURE

F i g - 9

BC1LINC WATER RrACTOR 1 0 0 0 KUe

OFF-GAS TREATMENT

PROCESS FLOW-SHEtTS