ML20149G048
| ML20149G048 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 05/02/1997 |
| From: | Lochbaum D UNION OF CONCERNED SCIENTISTS |
| To: | Diaz N, Dicus G, Shirley Ann Jackson, Mcgaffigan E, Rogers K, The Chairman NRC COMMISSION (OCM) |
| Shared Package | |
| ML20149G041 | List: |
| References | |
| IEB-80-17, NUDOCS 9707220416 | |
| Download: ML20149G048 (2) | |
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'A v1 UNION OF CONCERNED SCIENTISTS May 2,1997 Chairman Shirley A. Jackson Commissioner Kenneth C. Rogers Commissioner Greta J. Dieus Commissioner Nils J. Diaz Commissioner Edward McGafrigan, Jr.
United States Nuclear Regulatory Commission Washington, DC 20555-0001
Dear Chairman and Commissioners:
1 As reported in NRC Bulletins 80-17,80-17 Supplement No.1, and 80-17 Supplement No. 2,76 of the 185 control rods failed to fully insert following a manually initiated scram signal at TVA's Browns Ferry Unit 3 on June 28,1950. The cause of the event is generally attributed to blockage in the scram discharge volume which precluded complete drainage of the water coming from the control rods on the east side of the core.
I call your attention to the attached Atomic Energy Commission memo dated July 11,1973, from S.
H. Hanauer to J. M. Hendric, V. Stello, and T. Ippolito. In this memo, Mr. Hanauer reported that "An anonymous friend of mine in a utility" informed him that "The discharge pipes from the GE rod drives must be open (to the scram discharge volume) to allow the rods to scram." Mr. Hanauer stated that "It seems to me that these potential problems are indeed worth looking into." This concern essentially described the Browns Ferry event and pre-dated it by nearly seven years. I respectfully request a copy of all available documentation produced by or on behalf of the AEC (NRC) regarding the concern expressed in Mr. Hanauer's memo of July 11,1973.
I was a Shift Technical Advisor and Reactor Engineer at Browns Ferry at the time of the incomplete scram event. In fact,it was mere chance that I was not covering shift that night. The STA scheduled to work that evening took vacation and my supervisor and I flipped a coin to see who would cover.
Following the event, the Reactor Engineering section at Browns Ferry provided the General Electric Company with complete information on the operating cycle for Unit 3. GE's engineers in San Jose informed us that they were performing an analysis to determine the consequences from such an event occurring during a generator load rejection at rated power instead of during a manual scram from 36%
power. GE released NEDC-24276, " Evaluation ofIncomplete Control Rod Insertion Event at Browns Ferry 3," in October 1980. This report did not discuss the consequences from an event postulated at rated power. The Institute fot Nuclear Power Operations released NSAC/20, " Analysis ofIncomplete Control Rod Insertion at Browns Ferry 3," in December 1980. Section 4.6 of this report provided the results from GE's analyses for the actual evee.t and indicated that "further analysis is planned to explore the question of whether there are partial scram conditions which could carry the potential for fuel damage."
9707220416 970713 PDR ADOCK 05000259 H
PDR Washhgton Ofnce: 1616 P Street NW Suite 310 Washhgton DC 200361495 202-332-0900 FAX: 202-332-0905 Cambrktge Omes: Two Brattle Square Cambrkige MA 02238-9105 617-547-5552 FAX: 617-864-9405 Capomia Omce: 2397 Shattuck Avenue Suite 203 Berkeley CA 94704-1567 510-843-1872 FAX: 510-843-3785
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a May 2,1997 Page 2 of 2 Did GE ever provide the NRC will its analysis of the Browns Ferry incomplete control rod insertion.
j event for a postulated generator load rejection from rated power? If so, I respectfully request a copy of this analysis and the NRC's assessment. If not,I respectfully request the NRC to solicit this information from GE and place it in the Public Document Room. I also respectfully request a copy of al.1 available analyses produced by or on behalf of the NRC regarding the safety implications of the Browns Ferry event.
i Sincerely,
&Ust)0-David A. Loch aum Nuclear Safety Engineer attachment:
AEC Memo "Pote *ial for Common-Mode Failures in Instrumentation and Rod-Drive Systems," July 1*,1973.
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