05000361/LER-1982-008, Forwards LER 82-008/01T-0.Detailed Event Analysis Submitted

Forwards LER 82-008/01T-0.Detailed Event Analysis Submitted

ML20054C629
Person / Time
Site:	San Onofre
Issue date:	04/07/1982
From:	Ray H SOUTHERN CALIFORNIA EDISON CO.
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20054C630	List: 05000361/LER-1982-008, Forwards LER 82-008/01T-0.Detailed Event Analysis Submitted 05000361/LER-1982-008-01, /01T-0:on 820324,dilution of 0.7% Reactivity Occurred Due to Addition of 6,732 Gallons of Water from Refueling Water Storage Tank to Rcs,Resulting in 19% Shutdown Margin.Caused by Leaking Flow Valve 2FV-0210X
References
NUDOCS 8204210447
Download: ML20054C629 (2)

LER-1982-008, Forwards LER 82-008/01T-0.Detailed Event Analysis Submitted

Event date:
Report date:
3611982008R00 - NRC Website

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Southern California Edison Company W? Gy,3

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Office of Inspection and Enforcement

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Region V 1450 Walnut Lane, Suite 210 V

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Docket No. 50-361 m

Licensee Event Report 4

- 08 San Onofre, Unit 2 Attention: Mr. R. H. Engelken j

Regional Administrator

Dear Sir:

This letter describes a reportable occurrence involving the Chemical and Volume Control System. This submittal is in accordance with the reporting requirements stipulated in Section 6.9.1.12.d of Appendix A to the Facility Operating License NPF-10.

On March 24,1982, at 0830, Operations personnel began adding water to the Reactor Coolant System (RCS) from Refueling Water Storage Tank t

T006. A total of 6732 gallons of water was added to the RCS which resulted in a dilution in RCS boron concentration from 1972 to 1897 ppm.

A dilution of 30 ppm had been expected for this quantity of additional water. Therefore, an unplanned dilution of 45 ppm (0.70% delta k/k) occurred.

Investigation revealed that a leakage path existed from the Primary Makeup Water Tank to the Refueling Water Storage Tank (RWST) T006 which caused an unidentified dilution of T006 and T005. This, in turn, caused the unexpected dilution of the RCS which resulted in a Shutdown Margin of 19% delta k/k (Technical Specifications require at least 2% delta k/k for Mode 5). The requirement for a boron injection path was satisfied by the Boric Acid Makeup Tanks, and not the RWST, during this event.

The leakage path existed via two closed valves (2FV-0210X and j

S21901MU586) in the demineralized water makeup line to the Volume Control Tank. Leak rate was about 11 gpm. This relatively low leak rate was j

not noticed since the demineralized water (2FE-0210X) will not indicate i

flows less than about 17 gpm and the leak path existed only on an inter pg mittent basis when a third valve (S21208MUO54) connecting to the RWST was open.

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8204210447 820407 PDR ADOCK 05000361 S

PDR

, The two leaking valves will be reworked and repaired to prevent recurrence of this problem. An evaluation of the flow element will be conducted to determine if replacement with a more sensitive element is appropriate.

Should you require any further information, please contact me.

Sincerely, l

Attachment (LER No.82-008) cc:

U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Office of Management Information and Program Control Institute of Nuclear Power Operations (INP0)

A. E. Chaffee - USNRC Resident Inspector - Unit 2