ML20086B472

AO 50-267/74-8:on 740507,low Power Physics Tests for Helium in Reactor Prepared.Caused by Misinterpretation of Limiting Condition for Operation 4.9.1.Reactor Mode Switch Moved to Off Position & Breakers Opened

ML20086B472
Person / Time
Site:	Fort Saint Vrain
Issue date:	05/29/1974
From:	Swart F PUBLIC SERVICE CO. OF COLORADO
To:
Shared Package
ML20086B470	List: ML20086B468 ML20086B472 ML20086B474
References
AO-50-267-74-8, NUDOCS 8311170443
Download: ML20086B472 (4)

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DATE: Ifay 29, T974 Alm 010fAL OCCURRE!:CE FORT ST. VRAIt' :;UCLEAR GE'!ERATII:G STATION PUBLIC SERVICE C0::PA?.T Ol' COLORADO P. O. BOX 361 PLATTEVILLE, COLORADO 80651 . ,

REPORT NO. 50-267/74/8 .

Prclininary [ ,

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Final X IDENTIFICATI0:; 0F OCCURRENCE:

The following occurrence is considered an Abnormal occurrence under defi-nition 2.lb of the Technical Specifications.

On Ilay 7, 1974, following evacuation and backfill of the reactor vessel with helium, preparations were being nade to take the reactor critical to determine the dif ference in critical rod heir;ht with the core in air and heliu=. The ren ter 3:2 n -rer tchen eri incl. Or.ly tu: red gr up w ra withdrawn.

This operation was considered a violaticn of LCO 4.9.1 insofar as the reactor vessel had been backfilled with heliua and operation of the reactor is then considered to f all under category 2 of LCO 4.9.1 which requires co:apletion of all construction items and a sign of f by Regulat.ory Opera-tions prior to procecding with IIot Physics Tests in a helium environment and the power ascension program.

CONDITIONS PRIOR TO OCCURRENCE: Steady State Power Routine Ehutdown llot Shutdown Routine Load Chance Cold Shutdown X _0ther (specify)

Refueling Shutdown Low Power Physics Toots -

Routine Startup Reactor in IIellun 8311170443 740530 PDR ADOr,K 05000267 S PDR A

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Page 2 The major plant parameters at the time of the event were .is follows:

Power PTR, N/A INth

' ELECT, N/A 1%'c , .

Secondary Coolant Pressure N/A psig Temperature N/A 'F Plow N/A #/hr. .

Primary Coolant Pressure 78 psig Temperature 100 *F Core Inlet 100 *F Core Outlet Flow N/A // /hr.

DESCRIPTION OF

.O._CCU RRE::CC :

nn n , .,, 1, low , penp2rneinne tovo in pennvnee en endo tha vn,,nene neiein i in hellun iretediately following backfill of the reactor vessel to deternine the change in critical red height with the reactor in helium as conpared to those critical' red heights neasured in air. In addition, data uas to be taken to determine the e:: tent of a suspected problen concerning pernanent source placement and strength and their effect on the 1/M Curve for predictine, criticality.

We were questioned by the local net;ulatory Operations Inspector as to the permissibility of operating the reacter in heliua per the restrictions of LCO 4.9.1. A dinensalon was subsequently held with Directortte'of Licensina who advised that because of the wording of I.C0 4.9.1, all physics tests, not just ilot Physics Tent s in liclium were forbidden.

At the time of this converstation, two rod groups ucre fully uithdrawn and the reactor was suberitical. The control rods were returned to the core, the Reactor !!cdc Switch turned to the "Off" position and the key removed to the key cabinet in the Shift Supervisor's office.

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APPARE:TT CAUSE OF OCCUR 31'.::CE: Design Ununual Service Cend.

Including Environment

!!anu facturc Component Failure Installation /Conut. X Other (specify)

Operator lii;fnterprptation f _

_of LCO 4.9.1 Procedure ,

ANALYSIS OF OCCURRENCE:

Purnuant to Technical Specification 7.1.2, the Plant Operations Review Committec (PORC) uns convened to investigate the violction of the Limiting Condition of Operation, LCO 4.9.1.

The p0RC concluded that Station Management had not properly interpreted LCO 4.9.1. Ilot Physica Testing in the A series startup tests starts with SUT A-S, Reactivity Coefficient Iteasurcacutc. The words of LCO 4.9.1 for Phase I, in an air environnent, and Phase II in a helium environr:ent ucre not properly factored into the decision to proceed.

CORRECTIVE

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The Reactor !!ade Suitch has been moved to the "of f" position and the key removed and stored in the key cabinet in the Shift Supervisor's office.

In addition, the breakers on all the control rod drives have been opened to prevent any possible movement.

When necessary, to facilitate' Tcchnical Specification surveilln6cc testing, a Speedi-Mcmo authori::ing operation of the reactor node switch vill be issued by the Superintendent or Assistant Superintendent and this authori-s:ation chall be filed uith the Surveillance Test.

FAILURE DATA /

STMILAR OCCURRENCES:

No sinilar occurrences of this type reported.

PROCPECIATIC I!! PACT:

No proRrammatic impact expected.

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CODE I!!"ACT:

lione i

Approved:

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L!s:  ! 4si' s s W ,.qrd 1^

Fyederic C. Swart Superintcudent Fort St. Vrain l'uclear Generating Station e

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