ML19296B890

LER 80-003/03L-0:on 800121,nuclear Instrumentation Sys Power Range Channel 4 Declared Inoperable Due to Erratic Power Bistable Operation.Caused by Failed Ion Chamber Detector.Ion Chamber Detector Replaced

ML19296B890
Person / Time
Site:	North Anna
Issue date:	02/18/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19296B888	List: ML19296B887 ML19296B890
References
LER-80-003-03L-01, LER-80-3-3L-1, NUDOCS 8002220332
Download: ML19296B890 (2)

Text

{{#Wiki_filter:e (7-{7) ' LICENSEE EVENT REPORT CONTROL BLOCK: l l l l l l (PLEASE PRINT OR TYPE ALL REoUIRED INFoRMATION) I b 7 O 1 8 9 V l LICFNSEE A l NCODE l A l S l 1 l@l 0 l 0LICENSE 14 15 l - l 0l 0l 0l 0} 0l -l 0 0l@l4lIlIl1l1l@l NUMsEH 25 '6

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g 18 10 l _ 21 22 L--J 23 10 P 13 24 26 Ld 27 10131 28 29 IL I 30 l-] 31 Lo_] 32 T K N A ON ON PL NT T O HOURS 22 SSBNIT FOR B. SUPPLI R MANUFACT RER lC 33 lgl34Zl@ {g 35 W@ 36 l0]0l0l0l 3/ 40 W@ lNl@ W@ lWl1 2l0l@ 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i O 10riginally, the erratic behavior was attributed to a bad bistable but subse que nt I i i [ testing revealed that a failed ion chamber detector at the reactor veseel was the I i 7 lcause. Corrective action was to replace the ion chamber detector and verify l li;3l l the proper operation of N44. LLill8 l9 7 80 I STA $  % CAEa OTH ER STATUS DIS O RY DISCOVERY DESCRIPTION i s W@ 10 10 l0 l@lNA l [ A_J@l Operator Observation l ACTIVITY CC TENT RELEASED OF RELEA3E A*.'OUNT OF ACTIVITY LOCATION OF RELE ASE WW7 8 9

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Virginia Electric and Power Company North Anna Power Station, Unit #1 Attach =ent: Page 1 of 1 Doc ke t No. 50-338 Report No. LER 80-03/03L-0 Description of Event During startup operations on January 21, 1980, power range channel IV of the nuclear instrumentation system (N44) w..s declared inoperable when the high range, high power bistable was observed operating erratically. This event is contrary to T.S. 3.3.1.1 and reportable pursuant to T.S. 6.9.1.9.b. Probable Consequences of Occurrence The consequences of this event were limited because the affected channel was placed in the tripped condition within the hour and three redundant power range channels were available and functioning properly. As a result, the health and safety of the general public were not affected by this event. There are no generic implications associated with this occurrence. Cause of Event At first, the erratic behavior was thought to have resulted from a defective bistable. After several attempts to replace the bistable failed to correct the problem, it was determined that the actual cause of the malfunction was a failed ion chamber detector. Immediate Corrective Action The channel was placed in the tripped condition and replacement of the erratic bistable was attempted without success. As a consequence, the associated ion chamber detector located at the reactor vessel, was replaced and proper opera-tion of N 44 was verified. The power range channel was then declared operable and returned to its normal operating condition. Scheduled Corrective Action No scheduled corrective action is required. Actions Taken to Prevent Recurrence No further actions are required.}}