ML20058E319
| ML20058E319 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/22/1982 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | Adensam E Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8207280150 | |
| Download: ML20058E319 (2) | |
Text
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TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 374on 400 Chestnut Street Tower II July 22, 1982 Director of Nuclear Reactor Regulation Attention:
Ms. E. Adensam, Chief Licensing Branch No. 4 Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Ms. Adensam:
In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 In 1979 Westinghouse Electric Corporation identified to the NRC, Core Performance Branch, by letters dated November 15 and November 28, 1979 (Reference letter numbers NS-TMA-2162 and NS-TMA-2167), a concern with regard to certain assumptions utilized in the dropped rod accident safety analysis applicable to some Westinghouse NSSS designs. This concern was derived primarily from the potential for an unanalyzed power overshoot while in automatic control following selected dropped rod events which did not result in a reactor trip. The concern was applicable to all Westinghouse plants which rely upon the power range neutron flux high-negative rate reactor trip to mitigate the consequences of the dropped rod accident. Operating plants were notified of an unreviewed safety question under 10 CFR 50 59 and nonoperating plants notified of a significant deficiency under 10 CFR 50.55(e). Westinghouse recommended, and NRC subsequently required, certain operational restrictions above 90-percent power (either manual rod control or restricted rod insertion limits when in automatic rod control) to address this concern on an interim basis and to provide further evaluation.
It is our understanding that a meeting was held between members of the Core Performance Branch staff and Westinghouse to discuss the l
Westinghouse dropped rod evaluation process. This process demonstrated that the DNB design basis can be met for this FSAR Chapter 15 condition II event. We have been notified by Westinghouse that this evaluation process results in conclusions that will allow removal of the interim operating requirements on rod control and insertion.
It is also our understanding that an agreement has been reached between Westinghouse and members of the Core Performance Branch staff that the removal of operating requirements would take place after the NRC review l
of the information subsequently submitted by Westinghouse letter dated l
January 20, 1982 (Reference letter number NS-EPR-2545). This letter I
serves as notification that the dropped rod evaluation process documented by Westinghouse letter NS-EPR-2545, dated January 20, 1982 applies to Sequoyah unit 1, cycle 2 and Sequoyah unit 2, cycle 2.
The results confirm that the DNB design basis is met for the dropped rod accident. Based upon this method, it can be concluded that the interim restrictions on rod control and insertion vill no longer be necessary.
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8207280150 820722 PDR ADOCK 05000327 P
PDR An Equal Opportumty Employer
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. Director of Nuclear Reactor Regulation July 22, 1982 We formally request the NRC to review the material submitted by Westinghouse (NS-EPR-2545, January 20, 1982), and subsequently remove the interim operational restrictions effective with the startup of cycle 2 for both units. Approval is needed before startup of Sequoyah unit 1, cycle 2, presently scheduled for refueling outage in September 1982.
If you have any questions concerning this matter, please get in touch with J. E. Wills at FTS 858-2683 Very truly yours, TENNESSEE VALLEY AUTHORITY l,
. Mills, Manager Nuclear Licensing Sworn af subsc be before me this01r - Eday of 1982 h
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My Commission Expires /'
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U.S. Nuclear Regulatory Commission Region II Attn:
Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303
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