ML20212Q421
| ML20212Q421 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/20/1986 |
| From: | Heltemes C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Hebert R TERRY CORP. |
| Shared Package | |
| ML20209B180 | List: |
| References | |
| AEOD-C602, NUDOCS 8609050098 | |
| Download: ML20212Q421 (3) | |
Text
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1 August 20, 1986 Mr. Russell T. Hebert, Product Manager Products and Services AE0D/C602 Steam Turbine Division Terry Corporation P.O. Box 555 Windsor, Connecticut 06095
Dear Mr. Hebert:
Subject:
Case Study Report--Operational Experience Involving Turbine Overspeed Trips Following resolution of peer review comments received from INP0, the Terry Corporation, and various NRC offices, the Office for Analysis and Evaluation of Operational Data has finalized its case study report en operational experience involving turbine overspeed trips in light water reactors. We have enclosed a copy of our final report for your information and use as you may deem appropriate.
This study was performed in response to action item 8(f) of the actions directed by the EDO to respond to the NRC staff investigations of the June 9, 1985 event at Davis-Besse. A total of 128 turbine overspeed trip events involving AFW, HPCI and RCIC systems were reviewed. Overspeed trips of AFW turbines were found to be relatively widespread and one of the major causes for loss of operability or unavailability of AFW systems. This study concludes that the dominant attributed causes of AFW turbine overspeed trips are speed control problems associated with the governor, and trip and reset problems associated with the trip valve and overspeed trip mechanism. The governor speed control problems involve:
(1) slow response of the governor during quick startup, (2) entrapped oil in the Woodward Model PG-PL governor speed setting cylinder, (3) incorrect governor setting, and (4) wate_r induction into the turbine. The trip and reset problems stem from the complexity of reset operations and a lack of trip position indication. These problems are primarily the result of inadequate performance by plant personnel, inadequate procedures, and insufficient design considerations.
The enclosed case study report contains several specific recommendations aimed at addressing the root causes of the reported failures. These recommendations are currently being reviewed by the Nuclear Regulatory Commission staff.
A copy of the final case study report and this letter are being placed in the Public Document Room at 1717 H Street, N.W. Washington, D.C. 20555.
860905o098 860902 PDR ADOCK 05000346 S
4-Mr. Russell T. Hebert If you or your staff have any questions regarding this report, please contact Chuck Hsu of my staff. Mr. Hsu can be reached at (301)'492-4443.
Sincerely, Orches send er l
C. J. Mtwes, Jr.
C. J. Heltemes, Jr., Director Office'for Analysis and Evaluation of Operational Data
Enclosure:
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Mr. Russell T. Hebert If you or your staff have any questions regarding this report, please contact Chuck Hsu of my staff. Mr. Hsu can be reached at (301) 492-4443.
C. J. Heltemes, Jr., Director Office for Analysis and Evaluation of Operational Data
Enclosure:
As Stated DISTRIBUTION:
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8/[5'/86 iDATE : 8//f/86
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