ML20059D207

Intervenor Exhibit I-MFP-193,consisting of Review of LER 1-90-015-00,re Docket 50-275,dtd 910118

ML20059D207
Person / Time
Site:	Diablo Canyon
Issue date:	08/24/1993
From:	Richards S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
OLA-2-I-MFP-193, NUDOCS 9401070065
Download: ML20059D207 (2)

Text

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• fl Pacific Gas and Electric Company IE '. E -

pc sm - fi 77 Beale Street, Room 1451 @ '" C San Francisco, California 94106 pismsunon n Attention: Mr. J. D. Shiffer, Senior Vice President and General Managed NRAC Nuclear Power Generation nog HD C Gentlemen:

SUBJECT:

REVIEW 0F LICENSEE EVENT- REPORT 1-90-015-00 Thank you for your Licensee Event Report (LER) 1-90-015-00, transmitted by

• PG&E letter DCL-91-003, dated January 7, 1991, and titled "ESF Actuation, P-14 (High-High Steam Generator Water Level), Due to Feedwater Regulating and Bypass Valves Leakage."

Our review of the report indicates some clarification may be required. The report states that the root cause of the event on December 8, 1990, was valve leakage experienced during a startup from an inadvertent reactor trip. The report further states that, as an action to prevent recurrence,.

the leaking valves were subsequently repaired in late December after a second .

inadvertent reactor trip.

Our understanding of the event indicates that the valves discussed in the LER (main feedwater check valve FW 531, main feedwater regulating valve FW 530, and the main feedwater regulating bypass valve FW 1530) were observed to be leaking and causing level control difficulties during unit restart attempts or reactor trips in December 1989, February 20, 1990, February 22, 1990, and also on June 14 and June 19, 1990. Tnerefore it would appear the operators should not have been surprised by the leaking valves and either should have been pre-warned and provided with a strategy for dealing with.the leaking valves, or the valves should have been fixed at one of the earlier opportunities.

Operator statements after the Dacember 8,1990, event indicate that they were not aware of the valve conditions. _It appears that the lack of operator knowledge should be considered as a root cause and appropriate corrective action considered.

Additionally, the fact that the valves leaked should not have caused a rapic Re level drop in steam generator 1-3 unless the water had a location to which

$Qp to flow. Your LEP, does not describe the flow path. It _is our understanding mo that another valve, FCV420, the feedwater recirculation valve to the main S8 condenser, was found to have substantial seat leakage on December 21, 1990, "O during an operations walkdown done in response to inquiries as to where the g

oc feedwater was flowing. Therefore it appears that lack of timely investigative and corrective action after the previously observed level control events l R outlined above, may have been a contributing root cause and may indicate other O@ appropriate corrective actions are required. I RECEIVED

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l Further we understand the safety analysis results, which the LER states were not adversely affected, are being reevaluated by your personnel given the possibility that significant portions of auxiliary feedwater flow could have been diverted to the condenser by these leaking feedwater valves.

1 Please give this event and event report further consideration and revise the I report if appropriate.

In accordance with 10 CFR 2.790 (a), a copy of this letter will be placed in the NRt, rublic Document Room I Sincerely, I i

bd9 S. A. Richards, Chief I Reactor Projects Branch  !

1 cc: J. A. Sexton, PG&E R. F. Locke, PG&E J. D. Townsend, PG&E (Diablo Canyon)

D. A. Taggert, PG&E (Diablo Canyon)

T. L. Grebel, PG&E (Diablo Canyon)

News Services, PG&E State of California )

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