ML20138A942

Responds to 860129 Questions Re Difference in NRC Handling of TMI-1 860114 Reactor Protection Sys Trip Breaker Test Failure & Salem Feb 1983 ATWS.TMI-1 Problem Less Severe W/Much Lower Safety Significance

ML20138A942
Person / Time
Site:	Salem, Three Mile Island, 05000000
Issue date:	03/11/1986
From:	Blough A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:	Lewis M LEWIS, M.
References
NUDOCS 8603200217
Download: ML20138A942 (2)

Text

a N MAR 11 IEi Marvin I. Lewis 6504 Bradford Terrace Philadelphia, PA 19149 m

Dear Mr. Lewis:

Your January 29 letter asked why the NRC was handling the January 14, 1986 TMI-1 Reactor Protection System (RPS) trip breaker test failure so differently from the February 1983 Salem event involving RPS trip breakers. The answer is that the TMI-1 problem was less severe and had much lower safety significance.

The events were both handled appropriately, though vastly differently, under the NRC Enforcement Policy (10 CFR 2 Appendix C).

1 The Salem Anticipated Transient Without Scram (ATWS) involved failure of a safety function (i.e., automatic reactor trip) to work when called upon in an actual event (i.e., plant conditions exceeding the setpoint for a reactor trip). The event involved failure of the automatic trip feature on both of two redundant breakers. The event was initially not properly diagnosed; consequently, it recurred three days later. Also, our event review revealed significant programmatic problems regarding maintenance practices and quality assurance. The problem was classified as Severity Level I per the enforcement policy and a civil penalty was imposed.

The TMI-1 event involved partial failure of only one breaker. Although the shunt trip feature failed, the undervoltage (UV) trip feature on that breaker, as well as both the shunt and UV trips on redundant breakers, were operable.

Thus, loss of protection would not occur without multiple additional failures.

This event meets Severity Level IV per the enforcement policy. This event was identified by the licensee during testing designed to detect such failures.

We have found the licensee's test programs effective in this regard (see Weekly Status Report for February 21-28,1986). The licensee reported the failure to our inspectors and took corrective actions. Thus, per the Enforcement Policy, no Notice of Violation is to be issued. Nonetheless, we are interested in the licensee's long-term corrective action for this failure and, although no written report is required by regulations, our inspector obtained on January 14, 1986 a commitment from the utility to provide a comprehensive written report.

The conclusion (i.e. no Notice of Violation was planned) you reached from reading the Weekly Status Report was, in this case, correct. However, I wish to point out that the Weekly Status Report relates current plant events which could, in some cases, be the subject of later enforcement action. When an in-spection report is issued that contains enforcement, I plan to note that in the Weekly Status Report. But that will usually be several weeks after the event.

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3 Thank you for your interest and perceptive question.

Please note my proper address listed above.

Etsihal Signed By,t; Allen R. Blough, Chief Reactor Projects Section 1A Division of Reactor Projects n

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