ML19254F769
| ML19254F769 | |
| Person / Time | |
|---|---|
| Issue date: | 07/26/1979 |
| From: | Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Grier B, James Keppler, James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML19254F764 | List: |
| References | |
| NUDOCS 7911160552 | |
| Download: ML19254F769 (3) | |
Text
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.I-S$$RGYhRIAT RECORD C 4
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f July 25,1979 i'I'DRA'iDU't FOR:
B. H. Grier, Director, Region I J. P. O'Reilly, Director, Region II J. G. Keppler, Director, Region III K. V. Seyfrit, Director, Pegion IV R. H. Engelken, Director, Region V FT.0:.:
- h. C. Moseley, Director, Division of Feactor Oaerations Inspection, Office of Ir.saection and Enforcerer.t SU5 JECT:
I: C'.'LLETIM ' 0.79-050 & 79-000
'.UCLEAR MCICE"T AT THP.EE ".ILE ISLMD - SUPPLE"EMT The subject IE Eulletin snould be disratched for action today, to all WR nower racctor facilities with an operating license.
7,3 : ext of the Eu11etin and draft letter to licensees are enciesed for this rurpcse.
- ct-.an C.' 'esciey, Df: ector Civision of ;eactor O':erations Insnection Office of Inspection and Enforcement
Enclosure:
IE Bulletin 79-05C L 79-06C cc:
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(Draft letter to all PWR facilities with an operating license)
IE Bulletin Nos.79-05C & 79-06C Addressee:
The enclosed Bulletin 79-05C & 79-06C is forwarded to you for action.
Written responses are required.
If you desire additional information regarding this I
matter, please contact this office.
Sincerely, Sicnature (Regional Director)
Enciosure:
IE Bulletin Nos.79-05C & 79-060 D *
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1347 229
UNITED STATES NUCLEAR REGULATORY COMMISSION 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 July 26, 1979 IE Bulletin Nos.79-05C & 79-05C NUCLEAR INCIDENT AT THREE MILE ISLAND
. SUPPLEMENT Description of Circumstances:
Infonnation has become available to the NRC, subsequent to the issuance of IE Bulletins 79-05,79-05A, 79-05B, 79-06,79-06A, 79-05A (Revison 1) and 79-055, which requires modification to the " Action To Be Taken By Licensees" portion of IE Bulletins79-05A, 79-05A and 79-C55, for all pressuriced water reactors (PWRs).
Item a.c of Bulletin 79-05A recuired all holders of operating licenses for Babcock & Wilcox desianed PWRs to revise their ocerating procedures to soecify
- nat, in the event of'high pressure injection (HPI) initiation with reactor coolant pumps (RCPs) operating, at least one RCP per loon would remain operating.
Similar recuirements, applicable to reactors designed by other PWR vendors, were cor.tained in Item 7.c of Sulletin 79-06A (for Westinghouse designed -lants) and in Item 6.c of Bulletin 79-C63 (for Comoustion Engineering cesigned p Ents).
Prior to the incident at Three Mile Island Unit 2 (TMI 2), Westinghouse and its licensees generally adocted the position that the caerator should promctly trip all operating RCPs in the loss of cooiant acciden. (LOCA) situation.
Tnis Westinghouse position, has led to a series of meetings between the NRC staff and Westingnouse, as well as wi-n other PWR vendors, to ciscuss tnis issue.
In addition, more cetailed analyses concerning this matter were requested by tne NRC.
Recent preliminary calculations performed by Saccock & Wilcox, Westing-house and Comoustion Engineering indicate that, for a certain spectrum of small breaks in the reactor coolant system, continued operation of tne RCPs can increase the mass Icst 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 ooerating RC?, when two phase fluid was being pumoed through the reactor coolant sys em.
It is our current understanding that all three of the nuclear steam system supoliers for PWRs now agree that an acceptable action under LOCA symptczns is to trip all operating RCPs immediately, before significant voiding in the reactor coolant system occurs.
Action To Be Taken By Licensees:
In order to alleviate the concern i LOCA, all holders of operating lici DUPLICATE DOCUMENT following actions:
Entire document previously entered into system under:
14M01ol7/
ANO No. of pages:
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