ML19225D053
| ML19225D053 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 07/26/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Cavanaugh W ARKANSAS POWER & LIGHT CO. |
| References | |
| NUDOCS 7908060019 | |
| Download: ML19225D053 (1) | |
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UNITED STATES NUCLEAR REGULATORY C0:NISSION OFFICE OF INSPECTION AND ENTORCEMENT WASilING.DN, D.C.
20555 IE Bulletiu Nos.79-05C & 79-06C Date:
July 26, 1979 Page 1 of 1 NUCLEAE IMCIDENT AT THREE MILE ISLAND - SUPPLEMENT Descripi nn 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 raodification to the " Action To Be Taken By Lic nsees" 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 revisc their operating procedures to specify that, in the event of high pressure injection (llPI) 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 ltem 6.c of Bulletin 79-06B (fc; Combustion Engineering designed plants).
Prior to the incid"at at Three Mile Island Unit 2 (TMI 2), Westinghouse and its licensees generally adopted the position that the operator should pro: aptly t rip all operating RCPs ie the loss of coolant accident (LOCA) situation. This Westinghouse postion, has led to a series of meetings between the NRC staff and Westinghouse, as well as wi.th 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, Westinf;-
house and Combustion Engineering indicate that, for a certain spectrum of small breaks in the reactor coolant system, continued operation of the RCPs can increase the mass lost through the break and prolong or aggravate the uncovering 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 ste:na system suppliers for PWRs now agree that an acceptable action under LOCA symptoms is to trip all operating hCPs inaediately, before significant voiding in the reactor coolant system occurs.
Action To Be Taken By Licensees:
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In order to alleviate the concern over ec e
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LOCA, all holders of operating licensee
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