ML20086B129

AO 50-267/74-21:on 741121,high Pressure in Gas Waste Vacuum Tank Lifted Relief Valve Allowing Release of 700 Scf Uncontaminated Gas.Caused by Procedural Error.Investigation of Valve Seat Replacement Initiated

ML20086B129
Person / Time
Site:	Fort Saint Vrain
Issue date:	12/01/1974
From:	Rodgers W, Swart F PUBLIC SERVICE CO. OF COLORADO
To:	Howard E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20086B083	List: ML20086B079 ML20086B100 ML20086B107 ML20086B115 ML20086B123 ML20086B129
References
AO-50-267-74-21, NUDOCS 8311170065
Download: ML20086B129 (4)

Text

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\N pumie service company e osomeo P. O. Box 361, Platteville, Colorado 80651 3

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December 1, 1974 i

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4 q S NC E0 i Mr. E. Morris Howard, Director 2 4*]

Directorate of Regulatory Operations j I

Region IV, USAEC h f.. /f/

I P. O. Box 5039 White Settlement, Texas 76108 f, /(

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Dear Mr. Howard:

i Ref: Facility Operating License No. DPR-34 i

Docket No. 50-267 Enclosed please find a copy of Abnormal Occurrence Report No. 50-267/74/21, submitted per the requirements of the Technical Specifications.

Very truly yours, b 7' .M mG.a.L E .4-4I l _

Frederic E. Swart Superintendent Nuclear Production

. Fort St. Vrain Nuclear 6 Generating Station

, FES:11

, cc: Mr. Angelo Gianbusso I

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PDR l . .

12805

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f) 12',*~';I 7 4 RJ.T 0;1T I:*sT C:

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OCCHi:R'M: Cf: DATE: 31/2}/74 - - - -

8-FORT ST. VIM 1 ; NUCLEAR CT!!ERATI?$J STNTION PUBLIC SERVICC Cn: PANY OP C0f0PJ.D0 P. O. LOX 361 PLATTEVILLl:, COLORADO 80651 ,

El: PORT NO. 50-2f,7/74/21 l'reliminary IDI:!1TIFICATION OF OCCURRE':CE:

On November 21,1974,[high pressure in the gan vnut e vacuna tank ruptured a rupture dice and lif Led ri relief valve allowing en unauthori: cd releas.e of appro::i: ttely 703 Sci of uncontar.inated gas to the reactor buf1 ding ventilat. ion systen , This in identified as an abnornal occurrence per Technical Specifications 2.1.C.

C0!!DITIO :S PRIGR TO GCLi' :'C ICE: Routine Shuth :n Steady State Pouct flot Shutdown Routine Load Cb nr Cold Shutdown Other (noccify)

X Refueling Shutdown _ _ _

Routine Startup _

The najor pinnt parancters at the tinc of the event were as follows:

PTR, _ M/A __IMth Pouer ELECT, it/A INc Pressurc .t!/A . ,psig Secondary Coolant

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Tenporaturc , r/4 .__ *P Flow N/A #/hr.

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Presnurc . O knig Prita.ary Coolant.

Tenperature l'15 *P Core Inlet 135 , 'F Core Oatlet

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'Flov - 0 _.__#/hr.

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.DT;SCRIPTIO!; 0F OCCURMP':CP:

L'hile ventinn d n n the hellun purification regeneration nysten, to the nas vaste vacuun tanh, et the conclunion of t he renencration of "A" lov tenpernture nds.orber, hinh prensure on "A" rac vante nurn.' tank van nlarmed.

The reactor operator it'r.ediately nuitched t o the "B" t.nnk but the inlet valve (In*-6336) to "B" surge tank had been handjached shut, ef f ectively shuttinn of f the discharno flou path of both gar veste cenprennorn and lifting the relief valves on the discharge of the conprensors. The resul. tine, abrupt prensure increase in the vacunn tank caused the rupture disc and nafety valve to lue blown, relcaninn 4 700 SCF of ran to the ventilation nynten exhriunt. The ventilation cxhaunt i t, r.cnitored and thcce instrunenta nhnued no det ectahic

! change in count rate. Subcequest lab analysis of the "A" nurge tank contents contained that no detectahic activity van present in the gan.

i APPARE!!T CAUSE OF OCCURim! CE:

X Design Unusun1. Service Cond.

Including Environ.

Manufacture Component Tailure Inntn11ation/Connt. Other (specify) .

X Operator X Procedure ANAhYSIS OF I OCCUP.RE::CE:

s Design:

The isolation valves at the inlet to cach nan vaste nurne tank have leahed in the past and a practice han heen entabliched to set the handjack on a valve during a release f rca the tar.h to prs. vent in lenhane and release of unanalyzed gan. The handjach van net but not released af ter the tank was enpty.

Operator:

l A hold tag should have been placed on the handsvitch to alert the operator that the handjack on IP!-5336 uns net closed.

Procedure:

The valve list does not specifically lint a check of handjach removal or a test of valve operation.

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COP.[',itTIVC ti:TIO:::

Desi;,a :

Investination of replacing the seats in the inlet valve, llV-6335,36, to the ras vaste surge tank is ur.dcrway. A good seal in these valves could ruke the use of the handjr.ch unnecessary. .

A Plant Trcubic Report uill be insued to inventigate changing the viring so either ilV-6335 or !!V-6336 uill always he open.

Oper5 tor:

Operators vill be ist,utd a neno to place a "Il0LD" tr.g on the tank selector

'r,uitch when a handjach is set on either valve.

Procedure:

The valvc list vill be riodified to call f or handjack rer: oval af ter the discherne in cor.plete and includes a test of valve operation.

FA? LURE DATA /SIMILAR REP 0_RTED OCCURRE':CES:

1one PROCRA':li?. TIC l!!P/.CT:

!!ane CODE IMPACT:

!!one

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' i Subnitted by: 1/ - *lY" ** ~ 52LJ h ,

.h $ /y a,. . .- . .s U,

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D. Duane Rodptra ederic E. Svart Operations Supervisor Superintendent Iaclear Prod,uct.fonn Port St. Vrain ::aclear Generating Station G

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