ML20137Y186

Forwards AEOD/E514, Engineering Evaluation for Core Damage Precursor Event at Trojan. Most Serious of Five Events Occurred on 840920.Events Indicate Lack of Attention to Detail & Lack of Good Maint Practices

ML20137Y186
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	10/08/1985
From:	Zukor D NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:	Seyfrit K NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
Shared Package
ML20137Y190	List: ML20137Y186 ML20137Y198
References
AEOD-E514, TAC-60783, NUDOCS 8603120185
Download: ML20137Y186 (3)

Text

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October 8, 1985 AE0D/E514 MEMORANDUM FOR Karl V. Seyfrit, Chief Reactor Operations Analysis Branch 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:

ENGINEERING EVALUATION rep 0RT:

" CORE DAMAGE PRECURSOR EVENT AT TROJAN" The subject engineering evaluation report is enclosed for your information.

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, independent 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 of 3.5E-2 to 4.9E-3 de-pending upon the assumptions made. The significance of this event as a severe accident precursor and its potential consequences had not previously been recognized.

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. If the safety grade AFW pumps continue to demonstrate a poor reliability record, as in the past, the Region should take steps to require improvement.

Collectively, the five events indicate a lack of attention to detail, a lack of good maintenance practices, and a lack of appreciation of the significance of operating experience at other facilities. Positive actions to correct all of these deficiencies have been initiated.

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. Karl V. SeyG it The Region V Administrator met with the licensee on October 12, 1984 to discuss the significance of the Scptember 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.

4 6M t . D Dorothy J. I k , RMctor Systems Engineer Reactor Systems Section' 2 Reactor Operations Analysis Branch Office for Analysis and Evaluation of Operational Data

Enclosure:

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October 8,1985 MEMORANDUM FOR Karl V. Seyfrit, Chief Reactor Operations Analysis Branch AE00/E514 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:

ENGINEERING EVALUATION REPORT: " CORE DAMAGE PRECURSOR EVENT AT TROJAN" The subject engineering evaluation report is enclosed for your information.

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, independent 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 of 3.5E-2 to 4.9E-3 de-pending upon the assumptions made. The significance of this event as a severe accident precursor and its potential consequences had not previously been recognized.

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. If the safety grade AFW pumps continue to demonstrate a poor reliability record, as in the past, the Region should take steps to require improvement.

Collectively, the five events indicate a lack of attention to detail ~, a lack of good maintenance practices, and a lack of appreciation of the significance of operating experience at other facilities. Positive actions to correct all of these deficiencies have been initiated.

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