ML18052B160
| ML18052B160 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/30/1987 |
| From: | Wambach T Office of Nuclear Reactor Regulation |
| To: | Guldemond W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 8707060501 | |
| Download: ML18052B160 (2) | |
Text
50-255 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20665 June 30, 1987 MEMORANDUM FOR:
William G. Guldemond, Chief Projects Branch No. 2 Division of Reactor Projects Region III FROM:.
Thomas V. Wambach, Project Manager Project Directorate III-1 Division o~ Reactor Projects - III, IV, V
& Special Projects Office of Nuclear Reactor Regulation
SUBJECT:
PALISADES SHUTDOWN JUNE 20, 1987 - BOP Failures On June 20, 1987, Palisades Plant was taken to Hot Standby because of a crack in the EHC tubing that resulted in the turbine valve control oil being sprayed into the turbine building.
Following a manual trip of the turbine, there were several component failures in secondary-side equipment.
The Steam Generator 11A 11 Main Feedwater Regulating Valve failed to respond to *high steam generator level, the-Main Feedwater Pump P-lA high pressure trip and throttle valve failed to isolate, the steam inlet isolation valve to the moisture separator reheater failed to isolate, and one of the steam generator level indicators in the control room failed.
The NRC staff was concerned whether these failures reflected adversely on the effectiveness of the material condition improvement program instituted after the May 19, 1986, reactor trip and used as a basis for restart in March 1987.
As a result, the Project Manager was dispatched to assist in an on-site review of the circumstances of these failures.
The EHC system was included in the improvement program (Observation No.:
TGS-01).
Work was performed to stop internal leaks (MOOG valve and dump
~ valves) and external leaks (flared fittings).
In 1985, another EHC tube ruptured at the control block for another valve which had excessive leakage past the dump valves producing vibration.
At that time, all the flared ends of tubing to Nos. 1 and 4 governor valves and of the high pressure tubing to all other valves were inspected using DPT.
One tube showed a possible indication.
That tubing and the one that failed were replaced.
The tubing that failed on June 20, 1987, showed no crack indications.
During operation since the maintenance outage, the EHC system was monitored by system walk-down at least once a shift.
The failed tubing was replaced and the system has now been instrumented to allow detection and improved monitoring of vibrations during return to operation.
The Main Feedwater Regulating Valves were also included in the improvement program (Observation No. FWS-01).
The failure of the valve was attributed to a blockage of a 3-5 mil nozzle in the pneumatic controls for the valve by foreign ma.tter.
During the maintenance outage prior to this restart, the air system was systematically blown out including these lines for these valves.
The blow was checked for foreign material prior to completion.
The licensee now believes that a carbon steel valve harness around a filter in the air
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They, therefore, have now replaced the carbon steel ~,rl_th_ copper and installed a.five micron filter.
The remaining three fai.lures were in components that did not fall under the
~urview of the Material Condition Task Force bec~use there were no outstanding work orders on those components, there was no previous history of failures for the isolation vaJves, and the licensee had previously planned.replacement of the type indicators used for the steam generator level over a four-year period based on an undesirable "fail-as-is" feature and anticipated maintenanc.e problems with the servo-drive feature.
In addition, the isolation valves for the steam to the main feedwater pump turbines and to the moisture separator reheater would not have fallen under the scope of the Task Force as being components important to reliable p.l ant operation or safety related.
Based on the above considerations,. the staff concluded that these failures wou*ld not invalidate the conclusion, o.n plant readiness for operation.
Follow-up on the implementation of the specific' corrective measures for these failures is
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'/J0/87 OFFICIAL RECORD COPY Original signeq by Thomas V. Wambach, Project Manager Project Directorate 111-1 Di~ision of Reactor ~rojects - Ill, IV, V
& Special Projects
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