ML20037B600

Safety Evaluation Supporting Proposed Modified Offgas Treatment Sys

ML20037B600
Person / Time
Site:	Dresden
Issue date:	12/02/1974
From:	Silver R, Ziemann D US ATOMIC ENERGY COMMISSION (AEC)
To:
Shared Package
ML20037B599	List: ML20037B598 ML20037B600
References
NUDOCS 8010220720
Download: ML20037B600 (5)

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1} letter of harch 3,1973, ve inforc ef. Co mcrAccith 16iton '(Cz).

thct, in our opinion, the gescouc effluent release fre-Ircrden tr Ice cs trceticc'le cod-Ier,ucsted suwittcl cf plen=

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fer inctallction of an cupented off gas systcr.

Iy letter ci Jcrch 5,1574, CE submitted a report centoining a description cr.t. cuclysis

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of the proposed Unit 1 Fiodified Of f Gas -Trecteent Syster O CG);

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R c MC trill include equiprent and instrucentsticc te centrol relccse I

cf rcdiccctive.ctericls in caseous cificents iret 'thc -!:au.n Unit 1 rcin condenser air ejectors. At present,- the cir ejecter r.esects efilecnt

n-2 ntescs through a pipt taica provides A, cut, c ten cincte.h.q cna tnrce:.

prreiculate filters. -It then is relecsed to.the strorp..cre'vir:s I

'00-foot stock.

As proposed, the *;cscs vill itts tarce; '.cn' ceded t-reconbiner sunsystee, the existing coloup pipe, cne cn s_

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4 c:elcy cubsystc :.

It will then be released through tre c::ntin; pcrticulate e

filter installction and - the 300-f cot stcck.

Inc recorbinen subsystcc ccnverts the radiolytic hydro;cn cnd c::ygen in the cit pcs te Mtcr.

Ac a result, the ncn-condenscele:cffluent is grectl} re.iuccc in 'voltrc, t,ie 11cv rate into ti:c ' holdup pipe is reuucec ano tu reciocctive decay tire in the holdup. pipe is increased. Tae charcoci delcy sucsyste n

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rrovides selcetive adsorptien and deley of v.enons end 1 ryt tene in the cffluent resultin in c further reduction in rcdiccetive acteria.1 rc1cccc.

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. :.e. e.esirn ch,1ective of t.oc conce systu s is to rccccc tnc e d res rcticcctive relecte rcte irce the frecent sycte by c fcercr c! 1M.

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In our revi a of the preposed systen, ue evaluated enc syster integrity,.

redundcccy, cnd instrucentation. Uc also evalusted the en ccted

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performance of the syste:a in reducing radioactive efiluent to vclues lou as practicci and the radiological consequences of systen icilures.

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The licensce bcs etated that to assure cecepteble interrity, tne c er te.-

ill te G.ri st: cri corrtrected in cecc~ vec is

.reqcre qssci uc h, Lection mil c'd i..il M1.1 iceer t il r u, c.

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...nclude telcet,;oints, therever ' ;cs en., ic c'.e a c c f-Lellore-rec 1 vc1ve ste s.

In ccdition,. the syster it dedrnd te lf h vsi;'cr hiract to sr.intain its intc;;rity in the event ci c

, :ro;cc-cr: rcr deterctien.

Furtnertore, to'. reduce tnc car.rce fct-hydrogen-cry;cn..dctonation, the design utili:cs ster.n dilutien to 1-

=cintain hydrogen concentrations below the. lover. explosive licit.

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I-hydrogen cnclycer is provided'to assure that the reccrSiner 'is crcrcting

prcperly, itsed en cur evaluation of the consequences cf' loss of intecrity',

-ve consider the decirn criteria:for system interrity.to be cceeptabic.

It is our opinien, however, that hydrogen explosions:in.oif.rcs systces cecur trecuently enough to be consioered anticipatec cperctionci'

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cecurrences, rnd therefore thesradiocetivity. releasee.frer ruch vn _ event

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y ne tropcsed systes is equipped-vith rupture disks vnien.rclitve to

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the building accosphere 'in the cvent of an internal syster cr.plosion.

j-W In this regcrd re believe, bcsed en the infern:ction submitted,' thct M*

it rould Le prudent to add to' the rupture disk vent s ect.ac to: prevent-centinued relcase cf radioactivity following a rupture of the ~ rupture c 1 S,n.

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.cch subsyster of the added systcc has redundcat equi rent.

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t recerbiner subsysten consists ci two reccabiner trricr.

in cr or een trains may be selected.for operation.

Inc charcosi cclcy eutsytte-includes tre ecolcr-condenser trcins and'four chcreocl lect.

in thct subystcc cither cne cr toth coolcr-condenser trtinc rey we telected fcr operaticn.

The valving _fcr tne four chcrcoc1'becs is crranged

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se that various cc binations of beds' cy be selected..In our cpinion, q

the design includes sufficient redundcncy.to cssure that t..c syste:

car perfora its' function during periods of ncrr$1 ecuipr et.t 3mir tenace.

w The MCC sycter includes instrumentation _to moniter raciation, j

f lot: rate, pressure, humidity, tenterature.cnd hydrecen. le enistin rcdiction tenitor ct the beginning of the helcup pipe vill cci,tinuc to

t used to iscirte the of f gas systen upcn Cctcctico of hi;r rc ic-r:tivity.

i. centinuous nts scnplir:g reviter ct the cutle t ci tnc cc.crecc1 acc will tutonctically clerr in tne event concentreticus ti rMictetive nctcrisis in tbc cffluent excecJ e prcoc ter-i.e. vcltc.

ccue.icer the rotosed instrur.cntation acceptenle.

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.ri c.c'vctica of systc:. perforncnce tcs ' bescd en c1 cric : of the

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r.:.Or 's cnalysis cnd cur indercedent icnnlysis. -trcreen Unit 11 ncs a sirgleishell condenser; theretcrc, se hcve eq.loyd c vblee et 10- r e r :ir inlcci.cie in. cur enclysis. -laced on 'thc 3rrenctcrc riven-M l

in' Ap;cnci:: L to n Sii-1255, we cciculate'a nobic.ges relecse rete-tro:7 g--

the.ZCO of 5300 ci/yr, cnd we expect _that alnest-c11 ef tbc iodine Irom'

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~J this teurce vill he held zin' the charcoal.

'Ihe z licensee ' hcs cciculcted..

f a noblej as release rate frec.the EOG of 15,000 Ci/yr. :Ineclicensee's c

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~ higher vclue is due-to the assumption of a higher-air..iuleckcre rate (12 se!:) and a higher cff gas rate (100,000 pCi/sec ct 30 cinutes-

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. decay) used in their. evaluation. Le have used an oii 6ct tctect 30 L;p.

cirrte-ceccy of 70,000 pCi/sec, 'c rate.4hich we consider tac In cc... tion to gerc;ricte' design value-for a reactor of tints size.

at 9-O the affluent from the-MCO,1Ercsden.1 relecscs activity free other sourcce such ts the turbine gland-scal system exhaust and ventilction cir.

.4 These additional sources are esticated to_. release 1900 Ci/yr cf noble M

cses--cnd 0.35.ci/yr of 1-131.-

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.i Dresden-1 shcres c site with Dresden Lnits 2 and 3.

Yue rc6iorctivity relceses have been calculated-in th'e Final Environucut 1 dteterent i-fer-Enits 2/3 to be 46,000 Ci/yr/ unit of noble poet anc 0.34 Ci/yr/ unit of I-131.

Ecsed on our cycluation of all scurecc t.t the Lrcsden Etttien,-

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.1 (1) ::.e relecscs of radioactive a:cterials in ;csecus ciflecnt:: will ret :ccult in an cnnual cir dose,'et or beyona the site Jeundary, in

_T eces: cf-10 cred for rate: rcdiction cud 20. rcd for-tete radiction, c:::ccc 15 n rc.,

(1) tcc ennus1 thyroid-dose to en individual will net considering the location of the nearest dairy herd (2.'in.iles torth of the site), and l(3) tne annual qucntity of iodinc-131 - relccsed till

_g not exceed l'Ci for ecch recctor at the site.. 1:e consicer these deces

y and iedine release levels to be acceptable.

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Ce hcvc performed an independent analysis of the dose consequences of l:

e pcctulcted failure cf the proposed off ges syster for tresden Unit 1.

-'.re rnelysis censiders a nobic s cc position spccified in G. :..

-eticci Eerort TLIO 10734.

The ccicult.tica rce ccccc en c conscrvttively ni" relcese rcte ci ;31,000 nicrocurics per eccent riter A A - ira t c

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51--: inute ccicy line s.as assuned icr thic criculttien.

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- :17is iriict.tes tent c fr.ilure of the Lreeden.1 'off r cs systc; ccr>irtin-ci t cc:ci relcese vit' tin tro 1.ours ci the contents or tk delt.y tins end encrcoal beds, with stecm jet air ejector (5JAL) isolstic6 witriin-cne hour vill not result in c two hour whole body dose in excess of

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It-it cur position thct this dcsc ic'ic.: 1:nccch-.

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tog:cc.o:ce che need f or. cdditienol reasures. to reduce tw.g1<clineod p, s c Lce;. ecycnces.cf c loss cf intc.;rity.

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l e' hcVe revicted the systec's ccpability..to reduce: relecscs.ot radio-active :ctericls in gamous' effluents-to "as low as pri,cticcole': Icvelt

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in.accordcnce with 10 CFF. Ierts 20 cnd 50.36a considering norr.sl.crerctict ecd anticipated operational occurrences, ke hcve considered the design.

crevisions ' incorporated: to preclude hydrogen explosions ccd to control relesces of radiocetive =ctericis 'in,;cccous cffluentsi in accordance vith iencrcl Desirn Criterin' St; of /ppenci:: I to;10 U h'scrt 50. 'he.

1cve e.vclusted the appliccnt's systen dcccripticos,: process iloifdia;rtas, decipn cbjectives, cnd cesign criteric ter the: conponents' of the 1.0G.

system.

Ec' have perf creed cn independent calculation of toc:-rsdiolcriccl consecuences of.c loss cf 1.0G integrity.

Our basis for evaluation and f'; _

eccepttnceL har been confort-cnce =of the epplicent's designe, design-

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l criterio,-lced design bares fer ~ tne.easeous warte sytter to the cp;.licicle

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Cc-nissien regulcticus referenced clove, cs tell cs to stcff:tcchniccl-I

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positions cnd industry stcncarcs.

Lcsed on cur evalut. tion, % find tcet I

the preposed codified off res. trectrent systect is ceceptcel: cnd.prevides is recrercile crstrcnce that the'hecith cnd ecfet ei t.H ruclic cil1~

net be endentered.

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Richard D. Silver-l Operating Reactors Branch #2 i-Directorate of Licensing t

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Dennis L. Zie:cnn, Chief Operating Reactors Branch f2.

Directorate'of Licensing Dctc:

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10 CFE Pcrt 5c Section 50.34c - lublished Lcrch 16, 1571.

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1:1.02-1250 rinal Envirenacntcl Stateraent Concernic: Frepoccd Lule

..chint !ction:

l'unerical Guide for Desi;;n Ctjectives aru Limiting Conditions for Creration to Leet the Criterion As 1.cu t.s Frecticctle' for Ecdioactive Lcterial in Licht 'ecter-coolec a uclear 1over hesctor If fit:entc" Vel 2, July 1973.

1(;. ftJ4 i. A e, cnc rc.i. jus L111CLt1Cn iCr (.10S$ 11ica tiCli 0: &LI1UCat l

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Trectnent System as Group E,

Gencrcl E.lectric, February, i$73.

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