ML20210K872
| ML20210K872 | |
| Person / Time | |
|---|---|
| Issue date: | 04/22/1986 |
| From: | Heltemes C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Harold Denton, Minogue R, Taylor J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE), Office of Nuclear Reactor Regulation, NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| Shared Package | |
| ML20210K832 | List: |
| References | |
| NUDOCS 8604290099 | |
| Download: ML20210K872 (2) | |
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4' UN) ED STATES E ,epr%q'o,h~
NUCLEAR REGULATORY COMMISSION E WASHINGTON, D. C. 205S5 3
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MEMORANDUM FOR: Harold R. Denton, Director ,
Office of Nuclear Reactor Regulation 0 James M. Taylor, Director Office of Inspection and Enforcement Robert B. Minogue, Director Office of Nuclear Regulatory Research Thomas E. Murley, Regional Administrator, Region I .
J. Nelson Grace, Regional AdministNator, Region II James G. Keppler, Regional Administrator, Region III .
I Robert D. Martin, Regional Administrator, Region IV John B. Martin, Regional Administrator, Region V
. f FROM: C. J. Heltemes, Jr., Director Office for Analysis and Evaluation of Operational Data ,
SUBJECT:
REQUEST FOR PEER REVIEW COMMENTS--PRELIMINARY CASE STUDY-- -
OPERATIONAL EXPERIENCE INVOLVING TURBINE OVERSPEED TRIPS A preliminary AEOD case study report on nuclear plant operating experiences involving overspeed trips of auxiliary feedwater (AFW) system steam turbines is enclosed. The preliminary study also includes a review of overspeed trip events involving high pressure coolant injection (HPCI) system turbines and reactor core isolation cooling (RCIC) system turbines, to aid in the identification of c;uses for AFW turbine overspeed' trips. A total of 124 turbine overspeed trip events involving AFW, HPCI and RCIC systems were reviewed. The events studied occurred during the period from early 1972 to
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September 1985 and were identified primarily from Licensee Event Reports. ;
Each of the events involves a steam turbine designed and built by the Terry Steam Turbine Corporation and a governor supplied by the Woodward Governor Company. This study was performed in response to action item 8(f) of the actions directed by the ED0 to respond to the NRC staff investigations of the ~ June 9,1985 event at Davis-Besse.
Our preliminary study report concludes that the dominant 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 l 8604290099 860422 "
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3 overspeed trip mechanism. The governor speed control problems involve:
(1) slow response of the governor during quick startup, (2) entrapped oil in the Woodward M6 del PG-PL governor speed setting cylinder, (3) incorrect ;
governor setting, and (4) water 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 system 2 design considerations. Preliminary recommendations for preventing or reducing these unwanted turbine overspeed trips have also been developed and are included in the enclosed report. L In accordance with our " peer review" process and prior to finalization and !
distribution of our case study reports, we are providing a copy of the preliminary report for your review and comment. We are particularly f interested in obtaining your view on the accuracy and completeness of the [
technical details. Changes to the findings, conclusions, and recommendations will only be considered if the underlying information concerning the details of equipment design or systems operation is in error. Therefore, coments are being solicited on the technical accuracy of the report. The findings, [
i conclusions, and recomendations are provided for your i.nformation in order that you and your staff may understand the significanc'e which AE0D places on these events and obtain a more complete picture of the total report. We would welcome coments either informally by telephone' or formally by memorandum. By separate transmittal letters we have forwarded a copy of the preliminary report to the Terry Steam Turbine Corporation, INP0 and NSAC in order to solicit additional peer review coments.
Since we wish to issue the final report shortly, we ask that any coments be received by us within 30 days from receipt of the preliminary report. Should ,
your staff require additional time beyond that point, please let us know; otherwise, it will be assumed that there are no coments.
A copy of the preliminary report and this letter are being placed in the' Public Document Room at 1717 H Street, N.W., Washington, D.C. 20555.
If you have any questions regarding this study, please feel free to contact ,
Chuck Hsu of my staff. Mr. Hsu can be reached at (301) 492-4443.
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RdEteWeT,[Vr., Director 0 forAnalMisandEvaluation of Operational Data
Enclosure:
As Stated .
cc w/ enclosure: -
V. Stello, EDO T. Speis, NRR G. Arlotto, RES. A. DeAgazio, NRR D. Eisenhut, NRR R. Bosnak, NRR E. Jordan, IE I. Jackiw, RIII R. Bernero, NRR W. Johnston, NRR R. Baer, IE F. Miraglia, NRR B. Liaw, NRR R. Kiessel, IE H. Thompson, NRR ' R. Ballard, NRR J. Stolz, NRR 1
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