ML19270G105

LER 78-009/03L-0 on 780331:during Control Rod Testing, Rod Block Monitor a Was Bypassed Several Times.Caused by Supervisory Misunderstanding.Misunderstanding Clarified & Precautionary Procedures Added

ML19270G105
Person / Time
Site:	Vermont Yankee
Issue date:	04/28/1978
From:	Conway W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19270G103	List: ML19270G102 ML19270G105
References
LER-78-009-03L, LER-78-9-3L, NUDOCS 7906040258
Download: ML19270G105 (2)

Text

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LICENSEE EVENT REPORT LER 78-9/3L COP.TR'OL BLOCK: l l l l [ l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 1 6 7

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EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h O 2 l l 0 3 l Seeattadedsheet I O 4 1 1 0 5 l l O Wi l i O 7 I I O a i I 7 8 9 . 80 SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SUSCODE COMPONENTCODE SURCODE SUSCODE O 9 II la l@ [x j@ (JJ@ I z l z i z i z l z i z l@ l zi@ Iz l @ 20 7 8 9 10 11 12 13 18 19

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35 36 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i 0 [ l 3 , g See attached sheet I i 2 I I Ii 3 I l 1 4 l _J 7 8 9 80 STA  % POWER OTHE R STATUS OSCOV RY DISCOVERY 0ESCRIPTION 1 5 d @ loIo!9lhl NA I d hl NA I ACTivlTY CON TE NT RELEASED OF RELE ASE AMOUNT OF ACTIVITY LOCATION OF RELEASE 7

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PERSONNEL EXPOSURES NUVSER TYPE C E SC RIPTI O N i 7 Io of ol@lz l@l NA I

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VTVY S1 05000271 LER 78-9/3L Event Description and Probable Consequences During weekly surveillance testing of the control rods, the "A" Rod Block Monitor was bypassed several times after various control rods were inserted one notch and were then prevented from returning to their previous position. Tech. Spec. Table 3.2.5 requires that both Rod Block Monitors be operable in the RUN mode. However, one monitor may be removed from service for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> in order to perform maintenat.ce and/or testing. There were no similar events previously reported to the commission.

Cause Description and Corrective Actions The apparent cause of this event is attributed to a misunder-standing by the Shift Supervisor of an earlier instruction from the Operations Supervisor. The misunderstanding has been clarified and appropriate precautions; have been added to the station operating procedures.

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