ML19225D055
| ML19225D055 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 07/26/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 7908060024 | |
| Download: ML19225D055 (1) | |
Text
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[g ha R E Cgjg"'a UNITED STATES v
k.;k'hh'r',O.j NUCLEAR REGULATORY COMMISSION 3e a
REGION V
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'930 N. CALIFORNI A BOULEVARD o
SUITE 202, WALNUT CREEK PLAZ A g'9,,,,, "f WALNUT CR E E K, CAlt FORNI A 94536 July 25, 1979 Docket No. 50-344 Portland General Electric Company 121 S. W. Salmon Street Portland, Oregon 97204 Attention: Mr. Charles Goodwin Assistant Vice President Gentlemen:
The enclosed Bulletin 79-05C and 79-06C is forwarded to you for action.
Written responses are required.
If you desire additional infonnation regarding this matter, please contact this office.
Sincerely, f*'
$s R. H. En9elken Director
Enclosures:
1.
& 79-06C 2.
List of IE Bulletins Issued in Last 12 Months cc w/ enclosures:
B. Withers, PGE F. Gaidos, PGE 421 107 o
79 08000 ()7 zj
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UNITED STATES NUCLEAR REGULATORY CCMt1ISSION OFFICE OF INSPECTION AND ENFJRCEMENT WASHINGTON, D.C.
20E55 July 26, 1979
?.E Bulletin Nos.79-05C & 79-06C NUCLEAR INCIDENT AT THREE MILE ISLAND - SUPPLEMENT Description of Circumstances:
1 Information has beccme 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 79-068, which requires modification to the " Action To Be Taken By Licensees" portion of IE Bulletins79-05A, 79-06A and 79-068, for all pressurized water reactors (PWRs).
Item 4.c of Bulletin 79-05A recuired 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-C6B (for Combustion Engineering designed plants).
Prior to the incident at Three Mile Island Unit 2 (TMI 2), Westinghouse and its licensees genenlly adopted the position that the operator should promptly trip all operatino 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 cencerning this matter were requested by the NRC. Recent preliminary calculations performed by Babcock & Wilcox, Westing-hcuse and Combustion Engineering indicate that, for a certain spectrum of c
small breaks in the reactor coolant system, continued operation of the RCPs can increase the mass lost through the break and prolong or aqqravate 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 imediately, before significant voiding in the reactor coolant system occurs.
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Action To Be Taken By Licensees:
DUPLICATE DOCUMENT -
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In order to alleviate the concern over del
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LOCA, all holders of operating licenses fo Entire document previously entered following actions:
lhto system under:
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