ML20086E244

AO 75-04:on 750204,gradual Flow Reduction Discovered in Air Ejector Offgas Monitoring Sys.Caused by Removal of 3-way Solenoid Valve for Cleaning & Repair.Valve Replaced

ML20086E244
Person / Time
Site:	Vermont Yankee
Issue date:	02/05/1975
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086E235	List: ML20086E244
References
AO-75-04, AO-75-4, VYV-3644, NUDOCS 8312060437
Download: ML20086E244 (2)

Text

~

% gh L

VEnMONT YANKEM NUCLEAR 1*OWER CORPORATIO'N ScVctJTY CcVCr4 OROVC STRecT RUTi, ann, VI;1tMONT 05701 X 157 VcRrJOrd. VERMOtJT oS354 February 5; 1975 q

l I' \

Director I , hL' a Directorate of Regulatory Operations, Region I ,' ff;h m $.! '

United States Atomic Energy Commission F 631 Park Avenue 6 hg .e-'t King of Prussia, Pennsylvania 19406 5 ',(,\' ejp ut a &

REFERENCE:

Operating License DPR-28 Docket No. 50-271 Qh '

Abnormal Occurrence No. A0-75-04 (24 Hour Report)

Dear Sir:

As defined by Technical Specifications for the Vermont Yankee Nucicar Power Station, bection o. / , we are repon.ing the following Abnormal Occurrence as A0-75-04 and confirming our telephone conversation with your office.

At approximately 1035 on February 4,1975, Chenistry and Health Physicc personnel attccpted to determine the cause of a very gradual flow reduction in the Air Ejector Off-gas Monitoring system, which resulted in a corresponding decrease in activity level as indicated by the radiation monitors in the Control Room. The cause of the flow restriction was traced to a 3-way solenoid valve which was removed and replaced with a temporary Tygon bypass line. At approximately 1215, with the bypass line in place, flow inacdiately returned to normal.

During this period of 1 3/4 hours, the reduced flow rendered both channels of the associated Off-gas System Isolation instrumentation incapable '

of scusing the trip 1cvel settings of 0.3 Ci/sec. and 1.5 Ci/sec. as required by Technical Specifications Table 3.2.4.

The 3-way valve was cleaned, repaired and replaced by 1530.

0312060437 750214

. PDR ADOCK 05000271 s PDR 1484 J

r- u s- ~

L)3 g VERMONT YANKLu NuCLCAR POvVER CORPOD e ATION e .s Directorate of Ecgulatory operations February 5, 1975 Page 2 Because of the brief time periods during which the reduced and interrupted flow caused both channels of the trip system to be l unavailabic, and since the plant was utilizing the Augmented Off-gas System with its associated discharge monitors throughout the incident, the action required by Note 2 of Table 3.2.4 was deemed to be unnecessary.

The plant was operating at 99.7% power at the tinci l l

Very trul yours, O

hh-Bradford W. Rile

)bj/

3 PlantSuperintenby4 ,

e BMB/kbd

(

e

• 9 0

e 4

S e

e 4

4 O

e S

e

(.