ML20003B786

LER 81-006/03L-0:on 810113,steam Generator 11,level Channel D Placed Out of Svc Per Tech Specs to Correct Problem W/Ref Leg.Caused by Indication Deviation Among Redundant Safety Channels Due to Level Transmitter Valve leak-through

ML20003B786
Person / Time
Site:	Calvert Cliffs
Issue date:	02/12/1981
From:	Davis S, Rizzo P BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20003B785	List: ML20003B784 ML20003B786
References
LER-81-006-03L, LER-81-6-3L, NUDOCS 8102250521
Download: ML20003B786 (2)

Text

NRC FORM 366 U. S. NUCLEAR REGULATORY COMMISSION

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7 8 60 61 DOCKET NUM8ER 68 69 EVENT DATE 74 75 A EPORT DATE do EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h Io i2I I At 1110 Steam Generator (SG) #11 Level Channel "D" was niaced nut of I lo 1a i i service oer T.S. 3.3.1.1 to correct a oroblem with its reference lea. I l o 141 1 #11 SG Level Channel "0" was returned to service at 1100 on 1-14-81. I Io !sI I The three redundant channels remained operable durino the event. This I lo is 1 I is not a recetitive occurrence. I 1 o 171 l I 1o ta l I l CCDE ODE SL CO E COMPONENT CODE SL 8 CO D'E S ODE ioisi i II Al@ l X I@ LX,j@ l V I A Il I V I E l X l@ IX l@ LZJ @

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44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS liloll Level transmitter ecualizino valve leak-throuch is believed to have caused I li t i l I an indication deviation' amono redundant safety channels. Both 1-LT-11130 I ii,2, I and parallel-connected 1-LT-1111 (control channel) were affected. Indi- I iii3i l cation returned to normal after blowdown of the shared reference leo and I i i i # 41 l transmitter piping. No preventive action is deemed necessarv. I 7 8 9 80 STA  % PCwER OTHER STATUS 0$ RY DISCOVERY DESCRIPTION Ii 15 I l El@ l 015 l 0 l@l NA l l8l@l Durina Loa Readinos I i ACTIVITY CO TENT l

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LER NO. 81-06 DOCKET NO. 50-317 LICENSE NO. DPR-53 EVENT DATE 01-13-81 REPORT DATE 02-12-61 ATTACHMENT CAUSE DESCRIPTION AND CORRdCTIVE ACTIONS (CONT'D)

Operators had reported Channel L-lll3D indication deviated from that of the other three safety channels. (1-LIC-Ill3D indicated about 10 inches higher). Investigation showed control Channel L-1111 also was affected.

The transmitters share system connections to #11 Steam Generator. LT-1111 was removed from th! level control circuit.

Both transmitters were removed from service, their reference leg and equalizing lines were blown down. The reference leg was partially re-filled from the variable leg and time was allowed for completing the fill through steam condensation. When placed in service, all ill SG Level Channels were in agreement to within 1 inch.

i It is believed a smcIl leak existed in an equalizing or blowdown valve (less likely, due to redundancy) due to foreign material ca a valve seat.

The valves in question were operated and lines were blown down during the recent refueling outage. Foreign material could have entered a valve during lineup changes as the plant was being started up. No preventive action is deemed necessary due to redundancy of installations which in-clude 6 transmitters divided anong 4 sets of piping connections to the sys tem.

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