05000277/LER-1976-012, Telecopy LER 76-012/01P:on 760225,allowable Gross Activity Gaseous Release Rate Exceeded Tech Spec.Caused by Xenon Gases Released During Filter Demineralizer Backwash.No Immediate Corrective Action Possible

Telecopy LER 76-012/01P:on 760225,allowable Gross Activity Gaseous Release Rate Exceeded Tech Spec.Caused by Xenon Gases Released During Filter Demineralizer Backwash.No Immediate Corrective Action Possible

ML20086F838
Person / Time
Site:	Peach Bottom
Issue date:	02/25/1976
From:	Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
LER-76-012-01P, LER-76-12-1P, NUDOCS 8401090575
Download: ML20086F838 (2)

LER-2076-012, Telecopy LER 76-012/01P:on 760225,allowable Gross Activity Gaseous Release Rate Exceeded Tech Spec.Caused by Xenon Gases Released During Filter Demineralizer Backwash.No Immediate Corrective Action Possible

Event date:
Report date:
2772076012R00 - NRC Website

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f3 (v%iI LADE LPiiI A ELECTRIC COJA N T Peach Botton Atonic Pover Station

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Delta, Pennsylvania )

1731h February 25, 1976 Mr. Tadei P. O'Reilly, D. rector- }

Of ce of Inspection and En fo rc e=e nt United States Nuclear Redulatory Commission 631 Park Avenue Oj King of Prussia., Penncylvania. 19h 06- [M[ /

SUBJECT:

' REPORTABLE OCCURRENCE . PROMPT N O T I F I C A T.I.O N ,

Confirming R. S. Fleischennn's phone conversstion with Mr. Valt E n u n a c k ,. .R e g i o n. 1 , Uni:t e d S.t at e s Nuclear RegulaItary- '

Co=cicsion.co. Eebruary 25,.. 1976.

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Reference:

Docket Number 050-2.77 '

Unit No. 2 Technical 3'p ec i.fi c at io n R e f e re nc e :. 3.8.C 1 Report No.: 2-76-12/IP Occurrence D a t.e :. F e b r ua ry- 25,. 1974 Identifiention.of Cccurrence:

Exceeded Technical Specifi. cation 3.8.C.1. - Allevable Gross

( Activity-(Gasecus) release rate for.a short period o f ti=e .

Conditions Price to Occurrence:

Unit 2 a t- loo? power and Uni.t 3 at 60%.

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Plast gasecus re1 ease rate about ep 75.of. Technical S p e c.l fi.c ati.o n allowable.

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i Descriptien of Occurrence:

At 9: 40 n.c. on 2/25/76 the yni.t 2 roof vent radia. tion-=onitors spil upward.. It was estinat.ed. quickly that -it could have exceeded Technical Specification lini.ts.

Apparent Cause of Occurrence:

At 6:50 a . c .. o n 2/25/76 the 2A RWCU fil t e r decineralizer was I reno ved .from.'s e rvice to be backvashed and.preccated. The back-l vash vac started a t. about 9 : 4 0; a . n:. The vess'el vas left bottled.

This 50 ninuto hold apparently a11oved.some of the Icdine absorbed en the powdex resin to decay to Xenon. When.the RWCU vessel was

) onekusshed, the Xenon 6ases which had builtup in the vessel vere releasci to the bsekvAsh. receiving tank. The backwash receiving tank is vented to the ventilation system through a HEPA filter, which 'alloved tie. gases to be relenced fron the unit i ventilation stack. i Analysis of Occurrence:

The Unit 2 roof vent =cnitor spiked at about 9:hC a.n. ,The peak i instantaneous. release rate was calculated to be 2 3 5x10" uCi/sce. l l

This release- rate in abcut 3 9 ti=ec- the Technical Specification lisi.t. The main st ack and Unit 3 roof vent release rates renuined unchanged during the period that the 2 roof vent release rate was b, i g h.. In less than 10 ninutes the calculated l I

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0401090575 760225 gDRADOCK 050002[

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2uaaz wux Reportable Occurrence p.c 2 Prompt !io t i fi ca t i o rr 2-7 6-12 /IP,,

Unit 2 roof vent relesse rate was less than Technical Spec ificat i on. .lici.t s . The total. length o -f tice t hat .the-Unit 2 roof vent- release rate was higher than norcal was less than- 55 minut.esu ,,

Initial analysis.of the particulat.c filtern and iodine cartridges indiented..no s ig n i f i can.t in.c re as e in pa rt i e.ula t e.

or iodine relense. rates. /, n isot;opic analysis was run on.

a gas sacple-obtained at .t.h'er end of the release.. It indicated only.Xel35 and XeL33 It van esticated that the.

activity r e l e a-s e dm due to this-spike was ab ou t. 25 c.u ri e s (based on Oroam Radiat ion Roof. Vent Monitor Readings)..

The release c a l c ul a t i.o n s. for roof vent. releases contain a tt MPC of 3.- 3. !ia . uci /e e for a 10 minute old offgas =ixture per T e c h n i e nl S p e.e-i r i.c at i o n s . Ho we ve r. , in this case the.=ost ,.

liciting MPQLfor the eaj or activity vculd. be: 3N7 aci/ce.

If the. sust li=i.t itn g MPC.of activity.nessured is used.in the-r ele a-s e calcul.at: ion 40 the Technical Specification.relesse l ,

linit; i s. noCS. exceeded;. .,' , , .

! 3ased o n .t h e.n a b o v e g: the shoEb-tere l e n g.t h:.: o.f t h e release'and the fric t t hat: .th er .=aj or =ensurm.d . activi.ty were nob le gases, the *ef f e e t st..from:- t h.is re.leaoe should: :be, very mininn.li.

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l The- re leuse: ve.s shert . tern 'in nat ure ; n.o -incediate etrreetive-action'vas pos:s;ihle . Yurther. invest.igati'on vill be.=nde. L.nr.ra the .s ec h an i nc.. c.f release. The..procedu re. for b ackst.sah. anst.

precoat. of..the reactor v e.t e r e l>c a m.u p: filter decinerali- ers..

{ v.1 I.%. c e revise d' if improve =ents; aru. .found; to .dec re asc. the ,

6aseous reletse ratea. ..

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