05000361/LER-1982-125, Forwards LER 82-125/03L-0.Detailed Event Analysis Submitted

From kanterella
Jump to navigation Jump to search
Forwards LER 82-125/03L-0.Detailed Event Analysis Submitted
ML20069P198
Person / Time
Site: San Onofre Southern California Edison icon.png
Issue date: 11/22/1982
From: Ray H
SOUTHERN CALIFORNIA EDISON CO.
To: Engelken R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20069P201 List:
References
NUDOCS 8212070406
Download: ML20069P198 (2)


LER-2082-125, Forwards LER 82-125/03L-0.Detailed Event Analysis Submitted
Event date:
Report date:
3612082125R00 - NRC Website

text

_

  • o

. l\1 Southern California Edison CompanyQ? y WE S AN ONOFRE HUCLE AR GENER A TING ST A TION  !.

P.o. sox 12s S AN C LEMENT E. C A LIF ORNI A 92672 h' .

""" " " ^ " ^ " " November 22, 1982 oi" as "a U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596-5368 Attention: Mr. R. H. Engelken, Regional Administrator

Dear Sir:

Subject:

Docket No. 50-361 30-Day Report Licensee Event Report No.82-125 San Onofre Nuclear Generating Station, Unit 2

Reference:

Letter, H. B. Ray (SCE) to R. H. Engelken (NRC),

dated October 29, 1982 This letter provides the follow-up to the referenced interim report which was made in accordance with Technical Specification 6.9.1.13b.

The reported condition involved Limiting Conditions for Operation (LC0's) 3.4.1.4.2 and 3.4.1.4.1 associated with the Shutdown Cooling System (SCS). A final copy of LER 82-125 is enclosed.

As stated in the referenced letter, on October 1,1982, decreasing water level in Train A Component Cooling Water Surge Tank T-003 indicated a leak in the Component Cooling Water System (CCWS). Additionally, since the CCWS provides for heat removal from the SCS while in Modes 4, 5 and 6, Train A SCS was declared inoperable.

An investigation revealed that the root cause of Train A SCS inoperability was due to a chain of events beginning with failure of CCWS Surge Tank T-003's level control switch 2LSH-6498. This high-level shutoff switch failed to isolate make-up water from the Nuclear Service Water System being provided to the surge tank. The surge tank was filled solid and the resultant pressure increase caused relief valve 2PSV-6403 on Train A CCWS emergency chiller to lift. Additionally, the increase in pressure aggravated a pre-existing tube leak in the Train A CCW heat exchanger.

The leak was located and repaired as reported in the referenced letter.

8212070406 821122 PDR ADOCK 05000361 S PDR XE - 4 g) ^ll2 Y

R. H. Engelken November 22,1982 The CCW surge tank level control switch 2LSH-6498 was recalibrated.

The pre-existing tube leak is assumed to be the result of tube degradation caused by excessive impingement of seashells on the Saltwater Cooling System side of the tubes. As a result, an engineering investigation has been initiated to evaluate the feasibility of design modifications to the circulating water screens and rakes to preclude excessive seashell collection in the heat exchanger.

Since the redundant full capacity SCS train remained operable throughout the event, there was no impact on health and safety of plant personnel or the public.

If there are any questions regarding the above, please contact me.

Sincerely,

/0 - t,/

Enclosure:

LER 82-125 cc: A. E. Chaffee (USNRC Resident Inspector, San Onofre Unit 2)

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

_ . _ _ __ _ _ _ ._. __ _ -__ _