ML20202H211

Forwards Rev 1 to Engineering Evaluation Rept, Core Damage Precursor Event at Trojan. Revised Rept Addresses Region V Comments & Incorporates Some Addl Clarification in Selected Portions of Rept

ML20202H211
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	05/27/1986
From:	Zukor D NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:	Rubin S NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
Shared Package
ML20202H217	List: ML20202H211 ML20202H223
References
AEOD-E514, NUDOCS 8607160238
Download: ML20202H211 (3)

Text

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MAY 2 7 ISSG AE0D/E514 Revision 1 MEMORANDUM FOR: Stuart D. Rubin, Acting Chief Reactor Operations Analysis Branch 4 Office for Analysis and Evaluation of Operational Data FROM: Dorothy J. Zukor, Reactor Systems Engineer Reactor Systems Section 2 Reactor Operations Analysis Branch Office for Analysis and Evaluation of Operational Data

SUBJECT:

REVISED ENGINEERING EVALUATION REPORT: " CORE DAMAGE PRECURSOR EVENT AT TROJAN" The subject revised engineering evaluation report is enclosed for your infonnation. The original report was issued on October 8, 1985. Region V subsequently provided their comments to AE0D in October 1985 and again in April 1986. The revised report addresses these comments and incorporates some additional clarification in selected portiois of the report.

During 1984, five events occurred at the Trojan nuclear power plant which

- could have had serious consequences for equipment or personnel had they occurred under different circumstances. The potentially most serious event occurred on September 20, 1984 when multiple, indeper. dent undetected failures of safety-related components resulted in the partial loss of the emergency onsite power supply and the total loss of the safety-grade auxiliary feedwater system. The other four events are also discussed in detail in the report.

Our findings indicate that the September 20th event was a severe accident precursor with a conditional core melt probability on the order of IE-02 = .01 depending upon the a.ssumptions made. This is a very conservative probability as it does not take into account any surveillance tests detecting preexisting faults. It should be considered an upper bound. Although Region V recognized 1 the significance of the event, this report calculates a conditional core melt probability based on the actual plant conditions at the time and thus emphasizes and quantifies the seriousness of the event.

We found that the reliability of the safety grade AFW pumps was poor and resulted in the need to rely on the non-safety grade motor driven pump more than is desirable. The Region has taken steps to require improvement and it appears that improvement has been made.

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Stuart Rubin Collectively, the five events indicated a lack of attention to detail, a lack of good maintenance practices, and a lack of appreciation of the significance of operating experiences at other facilities. Positive actions to correct each of these deficiencies have been taken by Region V.

The Region V Administrator met with the licensee on October 12, 1984 to discuss the significance of the September 20th event. The Region emphasized that senior management must take more of an interest in the operation of the plant. They are also closely following the licensee's corrective actions, both short term and long term.

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Dorothy J. u or, eactor Systems Engineer Reactor Systems Section 2 Reactor Operations Analysis Branch Office for Analysis and Evaluation of Operational Data

Attachment:

1. Revised Engineering Evaluation

2. Revisions to E514 cc w/ attachment:

C. Trammel, NRR G. Johnston, Region V R. Dodd, Region V S. Richards, SRI

MAY 2 71986 Stuart Rubin Collectively, the five events indicated a lack of attention to detail, a lack of good maintenance practices, and a lack of appreciation of the significance of operational experiencies at other facilities. Positive actions to correct each of these deficiencies have been taken by Region V.

The Region V Administrator met with the licensee on October 12, 1984 to discuss the significance of the September 20th event. The Region emphasized that senior management must take more of an interest in the operation of the plant. They are also closely following the licensee's corrective actions, both short term and long term.

a l' Dorothy J. Z o , Reactor Systems Engineer Reactor Systems Section 2 Reactor Operations Analysis Branch Office for Analysis and Evaluation of Operational Data

Attachment:

l 1. Revised Engineering Evaluation Report i 2. Revisions to E514 cc w/ attachment:

I C. Trammel, NRR G. Johnston, Region V R. Dodd, Region V S. Richards, SRI Distribution:

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NAME :DZukor:rb/as:Plam 4411 : SRubin((f{:FHeb :CHe es  :  :

DATE :5/23/86 :5/23/86 :5/23/86 :5 /86  : /86  :  :

OFFICIAL RECORD ~ COPY

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