ML20214V036
| ML20214V036 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/04/1987 |
| From: | Shelton D TOLEDO EDISON CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 1384, GL-81-21, NUDOCS 8706110417 | |
| Download: ML20214V036 (1) | |
Text
TOLEDO
%mm EDISON DONAU] C. SHELTON Docket No. 50-346 Vce Prendert-Nudear (419) 24E2399 License No. NPF-3 Serial No. 1384 June 4, 1987 United States Nuclear Regulatory Commission Document Control Desk Washington, D. C.
20555 Gentlemen:
On May 5, 1981, the NRC issued Generic Letter 81-21 (Log No. 714), which concerned natural circulation cooldown. Toledo Edison responded to this letter and subsequent requests for additional information. Through these three letters (Serial Nos. 770, 969 and 1124), Toledo Edison justified the selected natural circulation cooldown rate of 1.5*F/ hour.
Toledo Edison has since reviewed the GPUN TMI-1 Topical Report 017, Revision 1, July 2, 1985 (Natural Circulation Cooldown Analysis Without Reactor Vessel Upper Head Void Formation) and has concluded that it is applicable to the Davis-Besse reactor vessel configuration. The method-ology described in the GPUN report odequately models cooling mechanisms at Davis-Besse. Therefore, Toledo Edison finds it acceptable to adopt the report's conclusions.
In order to preserve a degree of conservatism, however, rather than use the 50*F/ hour cooldown rate which the GPUN report justifies, Davis-Besse will allow a maximum 10*F/ hour cooldown rate when using natural circulation. This rate is easily controlled and results in a significantly decreased time to reach a condition where the decay heat removal system can be used for long-term cooling.
Davis-Besse is currently in the process of revising the cooldown procedure to utilize this new 10*F/ hour cooldown rate cooldown rate.
Very tru
- yours, DCS:DRB:plf cc: DB-1 NRC Resident Inspector A. B. Davis, Regional Administrator (2 copies) l 8706110417 870604
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DR ADOCK 05000346-PDR THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO. OHIO 43652
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