ML20199J307
| ML20199J307 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 11/11/1997 |
| From: | Hosmer J COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9711280105 | |
| Download: ML20199J307 (3) | |
Text
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I CO Opus I'lu r om nrn on,w n rmis s oi November i1,1997 United States Nuclear Regulatory Commission Washington, D.C. 20555 Attention: Document Control Desk
Subject:
llyron Nuclear Power Station, Units 1 & 2 Facility Operating Licenses NPF-37 & NPF-66 NRC Docket No. 50-454 and 50-455 13raldwood Nuclear Power Station, Units 1 & 2 Facility Operating Licenses NPF 72 & NPF 77 NRC Docket No. 50-456 and 50-452 Supplement to Response for Requu,t for Additional Information Regarding Primary Containment and Reactor Coolant System
References:
1.
J. Ilosmer (Comed) Letter to USNRC, Primary Containment and Reactor Coolant System Amendment, dated January 30.1997 2.
USNRC Request for Additional Information Regarding Primary Containment and Reactor Coolant System, dated March 20,1997 3.
J. Ilosmer (Comed) Letter to USNRC, Primary Containment and Reactor Coolant System RAI Response, dated May 23,1997 4.
J. Ilosmer (Comed) Letter to USNRC, P ; mary Containment and Reactor Coolant System RAI Response to Question #4, dated August 8,1997 In Reference 1, Comed submitted a request for a License Amendment in accordance with 10CFR50.90 regarding the revised calculated peak containment pressure, Pa, and the increased RCS volume. These changes are associated with the replacement steam generators to be installed on 13yron and llraidwood Units 1. Subsequent to that submittal, the NRC Staffissued a Request J
for Additional Informati< 1 regarding the proposed change (Reference 2) Comed responded to that request in References 3 and 4.
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U.S. Nuclear Regulatory Commission. November 11,1997 l
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- In the respon.;e to Question #3 (Reference 3), Comed committed to provide an update to the NRC Staff following resolution of r i issue pertaining to a main steam line break (MSLB) outside
- containment. The attachment to this letter is in response to that commitment.
t Please address any comments or questions regarding this information to Marcia Lesniak, Nuclear Licensing Administrator at (630) 663-6484.
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Sincerely.
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John B. Ilosmer.
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Regional Administrator-Rlli l
Byron /Braidwood Project Manager - NRR Senior Resident Inspector - Byron Senior Resident inspector - Braidwood j
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Supplemental Response For Request for Addit'onalInformation Regarding the Primary Containment and Reactor Coolant System Volume Hyron and Hraidwood Nuclear Power Stations NRC Question 3:
Provide a discussion of the potential main steamline break (MSLB) containment temperature profile effect of the replacement SGs, and the need to address the environmental qualification of equipment in containment and steamline spaces.
Supplemental Response to Question 3:
At issue was the qualification of equipment requireo A mg a MSLB event in the area outside containment. The concern was that superheated steam, caused by the uncovery of the steam generator tubes in a faulted steam generator, elevated temperatures in the confined area of the main steant pipe tunnel and safety valve enclosures. Peak transient temperatures occurred later in the transient than was initially considered. All equipment in the affected Environment Qualification (EQ) zone required to mitigate the transient has always been qualified for the time and conditions necessary to perform its safety function, which occurs early in the transient. Additional evaluation was necessary, however, to verify that instrumentation used for post-accident monitonng was qualified for the peak temperature which occurs late in the event. Tempera.ures are reduced significantly upon isolation of auxiliary feedwater fic1w to the faulted steam generator. The additional evaluation has been completed. The evaluation bounds the transient response from both the current Westinghouse D4 and D5 steam generators and the B&W replacement steam generators scheduled to be installed in Unit I for both Byron and Braidwood stations, werdwewpwaceme