ML19274E790

LER 79-037/03L-0 on 790323:unidentified Reactor Coolant Leak Greater than One Gallon Per Minute Detected.Caused by Packing Gland Leak in Pressure Control Valve.Valve Was Repaired & Normal Operation Resumed

ML19274E790
Person / Time
Site:	North Anna
Issue date:	04/18/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19274E780	List: ML19274E779 ML19274E785 ML19274E787 ML19274E790 ML19274E794
References
LER-79-037-03L, LER-79-37-3L, NUDOCS 7904240416
Download: ML19274E790 (2)

Text

NRC FORM 366 U. S NUCLE AR REGULATORY COMMISSION (7-77)

LICENSEE EVENT REPORT CONTROL BLOCK: 1 l l l l l l (PLEASE PRINT OR TYPE ALL REOUIRED INFORMATION) 1 6 7

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60 61 DOCKET NUMBEH 68 6') ' EVJNT DATE 14 75 REPOHT DATE So EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 lDuring steady state operation, an unidentified reactor coolant leakaoe areater than I lol3] l1 gallon per minute was detected. This event is reportable under T.S. 6.9.1.9.b. The I o 4 lh ealth and safety of the public were not affected. I o s l l lo I6 I l I 10171 1 l 10181 I l 7 8 9 80 DE CODE SUBCO E COMPONENT CODE SU8C DE SU DE 7

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J6 31 40 43 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h li 101 lUpon detection of the leakage, oower was reduced to 157, and a containment entrv and I lilii Isvsten walkdown was oerformed. The cause of the nroblem was a oackino cland laak in I i 2 la Pressure Control Valve. The valve was repaired and the olant returned to full power.1 liial l I i 4 l l 7 8 9 80 A s  % POWER OTHEH STATUS DISCOV HV DISCOVERY DESCHIPTION l1 Is 1 [.f_j @ l Ol 9 1 8 l @ l N/A l lAl@l Operator Observation l ACTIVITY CONTENT RELEASED OF RELE ASE AMOUNT OF ACTIVITY LOCATION OF RELE ASE i 6 [Zj @ [Z_j@l N/A l N/A l 7 8 9 10 ft 44 45 80 PERSONNE L E XPOSURES NUVHE R TYPF OESCRIPTION i >

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NUV8ER DESCRIPTION i a 7 8 9 1010101@l 11 12 N/A l 80 LOSS OF OH DAMAGE TO FACILITY TYPE DE SCHIP TIO N i 9 [Zj@l N/A l 7 8 9 10 80 7 90424 0 'll b. NRC USE ONLY 7

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80. Ts NAME OF PREPARER PHONE:

Virginia Electric and Power Company North Anna Power Station, Unit 1

Attachment:

Page 1 of 1 Docket No: 50-338 Report No: 79-037/03L-0 Description of Event At 1830 hours0.0212 days <br />0.508 hours <br />0.00303 weeks <br />6.96315e-4 months <br /> on March 23, 1979, during steady state operation, an unidentified reactor coolant leakage greater than 1 gallon per minute was detected. A backup leak rate test was performed. Reactor power was reduced to 15% and a containment entry was.made for a walkdown check.

Probable Consequences of Event Industry experience has shown that while a limited amount of leakage is expected from the RCS, the unidentified portion of this leakage can be reduced to a threshold value of less than 1 GPM. This threshold value is sufficiently low to ensure early detection of additional leakage. Since this leakage was immediately identified and the problem corrected, the health and safety of the public were not affected.

Cause of Occurrence ,

The cause of the problem was a packing gland leak in Pressure Control Valve 1455b.

Immediate Corrective Action Upon discovery of the leakage, the valve was backseated and the air removed.

Scheduled Corrective Action The valve was repaired during a maintenance outage.

Actions Taken To Prevent Recurrence To prevent recurrence, a high temperature packing was used to repair the valve.