ML19274G057
| ML19274G057 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 07/26/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Jeffery Grant TOLEDO EDISON CO. |
| References | |
| NUDOCS 7908290293 | |
| Download: ML19274G057 (1) | |
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UNITED STATES 8'
' 't, NUCLEAR REGULATORY COMMISSION 5
E REGION 'll o,
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799 ROOSEVELT ROAD e
GLEN ELLYN, ILLINOIS 60137 s
Docket No. 50-346 Toledo Edison Company ATTN:
Mr. James S. Grant Vice President - Energy Supply Edison Plaza 300 Madison Avenue Toledo, OH 43652 Gentlemen:
The enclosed IE Bulletin Nos.79-05C and 79-06C is forwarded to you for action. Written responses are required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, b
James G. Kepp er Director
Enclosure:
IE Bulletin Nos.79-05C and 79-06C cc w/ encl:
Mr. T. Murray, Station Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Harold W. Kohn, Power Siting Commission Helen W. Evans, State of
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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 July 26, 1979 IE Bulletin Nos.79-05C & 79-06C NUCLEAR INCIDENT AT TH2EE MILE ISLAND - SUPPLEMENT Description of Circumstances:
Information has become available to the NRC, subsequent to the issuance of IE Bulletins 79-05,79-05A, 79-05B, 79-06,79-06A, 79-06A (Revison 1) and 79-06B, which requires modification to the " Action To Be Taken By Licensees" portion of IE Bulletins79-05A, 79-06A and 79-06B, for all pressurized water reactors (PWRs).
Item 4.c of Bulletin 79-05A required all holders of operating licenses for Babcock & Wilcox designed PWRs to revise their operating procedures to specify that, in the event of high pressure injection (HPI) initiation with reactor coolant pumps (RCPs) operating, at least one RCP per loop would remain operating.
Similar requirements, applicable to reactors designed by other PWR vendors, were contained in Item 7.c of Bulletin 79-06A (for Westinghouse designed plants) and in Item 6.c of Bulletin 79-06B (for Combustion Engineering designed plants).
Prior to the incident at Three Mile Island Unit 2 (TMI 2), Westinghouse and its licensees generally adopted the position ti.at the operator should promptly trip all operating RCPs in the loss of coolant accident (LOCA) situation.
This Westinghouse position, has led to a series of meetings between the NRC staff and Westinghouse, as well as with other PWR vendors, to discuss this issue.
In addition, more detailed analyses concerning this matter were requested by the NRC.
Recent preliminary calculations performed by Babcock & Wilcox, Westing-house and Combu ": ion Engineering indicate that, for a certain spectrum of small breaks in t i reactor coolant system, continued operation of the RCPs can increase the mass lost through the break and prolong or aggravate the uncover-ing of the reactor core.
The damage to the reactor core at TMI 2 followed tripping of the last operating RCP, when two phase fluid was being pumped through the reactor coolant system.
It is our current understanding that all three of the nuclear steam system suppliers for PWRs now agree that an acceptable action under LOCA symptoms is to trip all operating RCPs immediately, before significant voiding in the reactor coolant system occurs.
Action To Be Taken By Licensees:
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.] g 4 In order to alleviate the concern over dela LOCA, all holders of operating licenses for following actions:
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