ML20054G374
| ML20054G374 | |
| Person / Time | |
|---|---|
| Site: |  |
| Issue date: | 06/11/1982 |
| From: | Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML20054G368 | List: |
| References | |
| LER-82-023-03L-03, LER-82-23-3L-3, NUDOCS 8206210496 | |
| Download: ML20054G374 (2) | |
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U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1) (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)
/0/1/ /V/A/N/A/S/2/ (2) /0/0/-/0/0/0/0/0/-/0/0/ (3) /4/1/1/1/1/ (4) / / / (5)
LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT O
~ R
/L/ (6) /0/5/0/0/0/3/3/9/ (7) /0/5/1/6/8/2/ (8) /0 /6 /1/1/8 /2 / (9)
DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)
/0/2/ / On On May 16, 1982 and again on May 17, 1982 while in Mode 5, the pressure in the/
f0/3/ / ni-J cogen reservoir for the pressurizer PORV (PCV-2455C) dropped below the minimum /
f0/4/ / pressure required to maintain the PORV operable. Since the pressure was restored /
/0/5/ / within the time of the T.S. 3.4.9.3.a action statement and the redundant PORV /
/0/6/ / remained operable, the health and safety of the public were not affected. This /
/0/7/ / event is reportable pursuant to T.S. 6.9.1.9.b. /
/0/8/ / /
SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE
/0/9/ /C/J/ (11) /B/ (12) /A/ (13) /V/A/L/V/E/X (14) /F/ (15) /B/ (16)
SEQUENTIAL OCCURRENCE REPORT REVISION LER/R0 EVENT YEAR REPORT NO. CODE TYPE NO.
(17) REPORT NUMBER /8/2/ /-/ /0/2/3/ / / /0/3/ /L/ /-/ /0/
(CTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT FAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER
[X/ (18) /F/ (19) /Z/ (20) /Z/ (21) /0/0/0/0/ (22) /Y/ (23) /N/ (24) /A/ (25) /M/1/2/0/ (26)
CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27) fl/0/ / Leakage in the PORV nitrogen supply system caused the reservoir pressure to /
/1/1/ / decrease. In addition, the curreat method for replenishing nitrogen supply is /
/1/2/ / inadequate. A design study has been completed and Jm system will be modified to /
'l/3/ / improve reliability. /
'1/4/ / /
FACILITY METHOD OF STATUS % POWER DISCOVERY DESCRIPTION (32)
'l/5/ /C/ (28) /0/0/0/ (29) / OTilER NA STATUS / ( } DISCOVERY
/A/ (31) / Operational Event /
ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35) LOCATION OF RELEASE (36)
/1/6/ /Z/ (33) /Z/ (34) / NA / / NA /
PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)
'l/7/ /0/0/0/ (37) /Z/ (38) / NA /
PERSONNEL INJURIES NUMBER DESCRIPTION (41)
':/8/ /0/0/0/ (40) / NA /
LOSS OF OR DAMAGE TO FACILITY TYPE DESCRIPTION (43)
'1/9/ /Z/ (42) / NA /
PUBLICITY ISSUED DESCRIPTION (45) NRC USE ONLY
/2/0/ /N/ (44) / NA /////////////
NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 __
8206210496 820611 PDR ADOCK 05000339 q PDR
Virginia Electric and Power Company North Anna Power Station, Unit No. 2-
Attachment:
Page 1 of 1 Docket No. 50-339 Attachment to LER 82-032/03L-0 Description of Event On May 16, 1982 and on May 17, 1982, while in Mode 5, the nitrogen supply that provides the operating medium for the pressurizer PORV decreased to below the minimum pressure required to maintain the PORV's operable. PORV operability is based on the design requirement for 120 valve cycles (1775 psig). Since the tanks were repressurized within the time frame of the Action Statement and the redundant PORV remained operable to provide overpressure protection, the health and safety of the public were not affected.
Probable Consequences of Occurrence The operability of the PORV's in cold shutdown conditions is required to ensure that the reactor coolant pressure boundary is not pressurized in the non-ductile range. The redundant PORV remained operable and there was no pressure transient. Therefore, there was no affect on the health or safety of the public.
Cause of Event The low nitrogen pressure condition was caused by excessive leakage in the nitrogen supply system and an inadequate method of replenishing nitrogen to the system. In addition, the setpoint on a relief valve within the system drifted low causing an additional leak path.
Immediate Corrective Action Additional nitrogen was supplied and thc supply tanks restored to the proper pressure. The setpoint on the relief valve was readjusted.
Scheduled Corrective Action No additional actions will be taken at this time.
Action Taken To Prevent Recurrence The nitrogen system has been reviewed to correct the operational problems. As a result, a design change is being developed. When implemented, the leakage experienced should be reduced and an adequate method for replenishing nitrogen supplies provided.
Generic Implications North Anna Units 1 and 2 have experienced excessive nitrogen system leakage since the system was installed.