05000338/LER-1980-003-03, /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

/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: 05000338/LER-1980-003, Forwards LER 80-003/03L-0 05000338/LER-1980-003-03, /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
References
LER-80-003-03L-01, LER-80-3-3L-1, NUDOCS 8002220332
Download: ML19296B890 (2)

LER-1980-003, /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

Event date:
Report date:
3381980003R03 - NRC Website

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 V l A l N l A l S l 1 l@l 0 l 0 l - l 0l 0l 0l 0} 0l -l 0 0l@l4lIlIl1l1l@l l l@ O 1 '6 LICENSE TYPE JO b7 CAI $8 7 8 9 LICFNSEE CODE 14 15 LICENSE NUMsEH 25 / CON'T Zu"C' lL l@l 0 l 5 l 0 l 0 l 0 l 3 l 3 l 8 @l 0 l1 12 l1 l 8 l0 l@l0l2 11 l8 l8 lo l@ o 1 7 8 bo 61 DOCKET NUMuER 68 6'> EVENT DATE 14 75 HEPOR T DAT E 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h O 2 On January 21, 1980, with the unit in Mode 2, NIS power rance channel IV (N-44) I l was declared inoperable due to erratic operation of the high range power bistable. I O 3 l Since redundant power range channels were available and functioninst proDeriv. tha I o 4 o s health and safety of the general public were not af fected. Reportable pursuant to l 0 s T. S. 6.9.1.9.b. I 10171I I O s I l 80 7 8 9 SYSTEM

CAUSE

CAUSE COMP. VALVE CODE CODE SUSCODE COMPON ENT CODE SU8 CODE SUSCODE lIlAl@ y @ El@ l I l N I S l T l R l U lh Fl@ J @ O 9 7 8 9 10 11 12 13 18 19 20 SEQUEN TI AL OCCURRENCE REPORT REVISION LER EVENT YEAR R E POR T NO. CODE TYPE N O. @ sgo/RO 18 10 l L--J 10 P 13 Ld 10131 IL I l-] Lo_] a g _ 21 22 23 24 26 27 28 29 30 31 32 T K N A ON ON PL NT T O HOURS 22 SSBNIT FOR B. SUPPLI R MANUFACT RER lC lgl34Zl@ {g W@ l0]0l0l0l W@ lNl@ W@ lWl1 2l0l@ 33 35 36 3/ 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 10riginally, the erratic behavior was attributed to a bad bistable but subse que nt I i O i i [ testing revealed that a failed ion chamber detector at the reactor veseel was the I lcause. Corrective action was to replace the ion chamber detector and verify l i 7 li;3l l the proper operation of N44. LLill l I 7 8 9 80 STA $ % CAEa OTH ER STATUS DIS O RY DISCOVERY DESCRIPTION W@ 10 10 l0 l@lNA l [ A_J@l Operator Observation l i s ACTIVITY CC TENT RELEASED OF RELEA3E A*.'OUNT OF ACTIVITY LOCATION OF RELE ASE NA l NAl W W @ l Z l@l 7 8 9 10 11 44 45 80 PERSONNEL EASOSLRES NUMBER TYDE C E SCRIPTION l 0 l 0 l 0 l@l Zl@l NA 1 7 ,E R SO~ N E L'4 ES NUMBER O ESCRIP TION NA l [IlT) l 0 l 0 0l@l 7 8 9 11 12 80 LOSS OF OR OAVAGE TO FActLITY L'19J lZ J@l NA 80 0999n M1 1 TYPE

DESCRIPTION

~ ~ " 7 8 9 10 80 PU t3 LICI TY NRC USE ONLY y [N_j@ DESCRIPTION ISSUED l NA l 1ll lllllllll*; 7 8 9 10 68 69 80 5 o Cn enight PHONE: ('03) $4 3131 NAME OF PREPARER "_ o

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. }}