ML19344A737
| ML19344A737 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 07/24/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Groce R Maine Yankee |
| References | |
| NUDOCS 8008220107 | |
| Download: ML19344A737 (1) | |
Text
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<,9 UNITED STATES
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NUCLEAR REGULATORY COMMISSION t
j REGION 1 C
631 PARK AVENUE
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KING OF PRUSSIA, PENNSYLVANIA 19406 July 24, 1980 0 cket No. 50-309 Maine Yankee Atomic Power Company ATTN:
Mr. Robert H. Groce Senior Engineer - Licensing 25 Research Drive Westborough, Massachusetts 01581 Gentlemen:
The enclosed IE Bulletin No. 80-18, " Maintenance of Adequate Minimum Flow Thru Centrifugal Charging Pumps Following Secondary Side High Energy Line Rupture,"
is forwarded to you for action.
A written response is required.
In order to assist the NRC in evaluating the value/ impact of each Bulletin on licensees, it would be helpful if you would provide an estimate of the manpower expended i.n conduct of the review and proptration of the report (s) required by the Bulletin. Please estimate separately the. maapewer associated with corrective actions necessary following identification of problems through the Bulletin.
If you desire additional information regarding this matter, please contact this office.
Sincerely, W2-YY.
- llQ, B ce H. Grier irector
Enclosures:
1.
IE Bulletin No. 80-18 and Enclosure with 2 Attachments 2.
List of Recently Issued IE Bulletins CONTACT:
E. G. Greenman (215-337-5267) cc w/encls:
E. Wood, Plar,t Superintendent E. W. Thurlow, President 8 0082 2 0 t o 7
SSINS No.: 6820 Accession No.:
UNITED STATES 8005050062 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 IE Bulletin No. 80-18 Date:
July 24, 1980 MAINTENANCE OF ADEQUATE MINIMUM FLOW THRU CENTRIFUGAL CHARGING PUMPS FOLLOWING SECONDARY SIDE HIGH ENERGY LINE RUPTURE Description of Circur. stances:
Letters similar to the May 8, 1980 notification made pursuant to Title 10 CFR Part 21 (enclosure) were sent from Westinghouse to a number of operating plants and plants under construction (list, within enclosurs) in early May, 1980.
The letters and the enclose'd "Part 21" letter contain a complete description of the potential problem summarized below. The letters indicated that under certain conditions the contrifugal charging pumps (CCPs) could be damaged due to lack of minimum flow before presently applicable safety injection (SI) termination criteria are met. The particular circumstances that could result in damage vary somewhat from plant to plant, but involve unavail-ability of the pressurizer power operated relief valves (PORVs), with operation of one or more CCPs repressurizing the reactor during SI following a secondary system high energy line break. Since the SI signal automatically isolates the CCP mini-flow return line, the flow through the CCPs is determined by the individual pump characteristic head vs. flow curve, the pressurizer safety valve setpoint, and the flow resistances and pressure losses in the piping and in the reactor core. That minimum flow may not be adequate to insure pump cooling, and resulting pump d uage could violate design criteria before current SI termination criteria are met.
Westinghouse recommends that plant specific calculations outlined in the letter (enclosure) be performed to determine if adequate minimum flow is assured under all conditions. If adequate minimum flow is not assured, Westinghouse recommends specific equipment and procedure modifications which will re:, ult in adequate minimum flow. The recommended modificatior.s assure availability of the necessary minimum flow by assuring that the mini-flow bypass line will be open when needed, but will be closed at lower pressures when the extra flow resulting from bypass line closure might be necessary for core cooling.
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