ML20072A110
| ML20072A110 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 05/27/1983 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Varga S Office of Nuclear Reactor Regulation |
| References | |
| TAC-51720, NUDOCS 8306090368 | |
| Download: ML20072A110 (2) | |
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Telephone (412) 4564000 Nuclear Division P.O. Box 4 Shippingport, PA 150774004 May 27, 1983 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission At tn :
Mr. Steven A. Varga, Chief Operating Reactors Branch No. 1 Division of Licensing Washington, DC 20555
Reference:
Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 Request to Remove Operational Restrictions on Rod Control Gentlemen:
In 1979, Westinghouse identified to the Core Performance Branch a concern with regard to certain assumptions employed in the dropped rod accident safety analysis applicable to some Westinghouse NSSS designs.
This concern was denied 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 when operating in power ranges in excess of 90 percent.
The concern was applicable to all Westinghouse plants which rely upon the Power Range Neutron Flux-High Negative Rate Reactor Trip to mitigate the consequence of the dropped rod accident. Duquesne Light Company was notified by Westinghouse of an Unreviewed Safety Questi i under 10 CFR 50.59 applicable to Beaver Valley Power Station, Un1
%. 1.
Westinghouse recommended and the NRC subsequently required certain oper-ational restrictions above 90% 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.
We understacd that the new Westinghouse Dropped Rod Evaluation Process has been reviewed and found acceptable by the NRC staff (Ref-erence 1).
This process demonstrates that the DNB design basis can be met for this Condition II event and results in conclusions allowing removal of the interim operating restrictions on rod control and insertion.
By letter dated Iby 23,1983 (Cycle 4 Reload Safety Evaluation Report),
we stated that the Dropped Rod Evaluation Process has been applied to the Cycle 4 design and will be applied to future cycle designs.
Based upon these results which confirm that the DNB design basis is met for the Droppec Rod accident, it can be concluded that the interim restrictions on rod automatic control are no longer necessary, 8306090368 830527 PDR ADOCK 05000334 I
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,B;tver V:lley Powar St: tion, Unit No. 1 o
Docket No. 50-334, License No. DPR-66 Request to Remove Operational Restrictions on Rod Control Page 2 Therefore, we formally request notification from the NRC that the interim operating restrictions on automatic rod control can be removed, effective with BVPS Unit 1 Cycle 4.
Reference 1:
Acceptance for Referencing of Licensing Topical Report WCAP-10297 (P), WCAP-10298-(NS-EPR-2545) Entitled " Dropped Rod Methodology for Negative Flux Rate Trip Plants".
Very truly yours, 6fAk J. J. C.arey resident, Nuclear Vice r cc:
Mr. Peter Tam, Project Manager U. S. Nuclear Regulatory Commission Phillips Building Washington, DC 20555 Mail Stop 438 -
Mr. W. M. Troskoski, Resident Inspector U. S. Nuclear Regulatory Commission Beaver Valley Power Station Shippingport, PA 15077 U. S. Nuclear Regulatory Commission c/o Document Managment Branch Washington, DC 20555