ML20040D749
| ML20040D749 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 01/27/1982 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| 770, A82-68B, GL-81-21, NUDOCS 8202020216 | |
| Download: ML20040D749 (4) | |
Text
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Docket No. 50-346 g
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Mr. Darrell G. Eisenhut, Director Division of Licensing Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
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Dear Mr. Eisenhut:
This letter is in response to the NRC Generic Letter No. 81-21, Log No. 714, dated May 5, 1981, on the St. Lucie Natural Circulation Cooldown as applicable to Davis-Besse Nuclear Power Station Unit 1.
Attached is Toledo Edison's re-quired response.
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THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEOO, OHIO 43652
SUBMITTAL IN RESPONSE FOR.
DAVIS-BESSE NUCLEAR POWER STATION UNIT 1 FACILITY OPERATING LICENSE NO. NPF-3 This letter is submitted in conformance with 10 CFR 50.54(f) relating to Mr.
Darrell Eisenhut's letter dated May 5, 1981.
This deals with the training and procedural guidance implemented as a result of the St. Lucie Natural Circulation Cooldown, in order to cooldown safely in that mode with the avoidance / recognition of reactor vessel voiding.
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Docket No. 50-346 License No. NPF-3 Serial No. 770 RESPONSE TO GENERIC LETTER NO. 81-21 (NATURAL CIRCULATION COOLDOWN)
Item 1:
A demonstration that controlled natural circulation cooldown from operating conditions to cold shutdown conditions, conducted in accordance with our procedure should not result in reactor vessel voiding.
Response: Toledo Edison feels that a demonstration or analysis to prove that no reactor vessel voiding will occur would not be totally conclusive considering the many variables that could be involved in a natural circulation cooldown.
It would therefore be impractical to try to prove that voiding will not occur in every possible situation.
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It is felt, however, that the Shutdown and Cooldown Procedure used, incorporating Babcock and Wilcox's guidelines on natural circulation, is sufficient to prevent reactor vessel void formation._ Even if a voiding situation should occur, Toledo Edison is further-satisfied that due to the procedural guidance given, the operators will be able to quickly recognize the situation and-take the proper correc-tive action. Toledo Edison is confident then that the procedures-used are adequate to safely cooldown on natural circulation with proper recognition and corrective action in case of a void formation.
Item 2:
Verification that supplies of condensate grade auxiliary feedwater are sufficient to support our cooldown method.
Response: Toledo Edison has performed an analysis verifying that the condensate storage capacity is sufficient to support the cooldown based on our procedural method.
Item 3:
A description of the training program and the provisions of.our pro-cedures that deal with prevention or mitigation of reactor vessel voiding.
Response: The Training Department covered the St. Lucie circular in operator training classes from July 3 to July 31, 1980. The operators were also required to review all the procedural changes concerning natural circulation and void formation.
A new section has been added to the shutdown and cooldown procedure to handle a natural circulation cooldown. These directions were incor-porated from Babcock and Wilcox's Interim Guidelines, calling for a 20*/ hour cooldown rate which will allow the hotter water in the head region to come into equilibrium with the bulk coolant. This is done while maintaining a 50* subcooling margin.
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Docket No. 50-346' License No. NPF-3 Serial No. 770 -
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Upon.a rapid increase in pressurizer level, the procedure calls for l
stopping the-cooldown and depressurization and increasing the pres-sure using the' pressurizer heaters and makeup pumps.- Pressure is increased to'as high as practical while maintaining reactor vessel.
pressure-temperature' limits. High pressure injection pumps are used to maintain the 50*F subcooling margin.
'With'these items covered in the training program and procedures, a safe-cooldown on natural circulation is expected.
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