ML19323G707
| ML19323G707 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 05/08/1980 |
| From: | Heider L VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-80-07, IEB-80-7, WVY-80-70, NUDOCS 8006060511 | |
| Download: ML19323G707 (2) | |
Text
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VERMONT YAN KEE NUCLEAR POWER CORPORATION SEVENTY SEVEN GROVE STREET B.4.1.1.
RUTLAND, VensoxT osvon WVY 80-70 R EPLY TO:
May 8, 1980 ENGINEERING OFFICE TURNPIKE ROAD WESTBORO. M ASS ACHUSETTS 01591 United States Nuclear Regulatory Commission TELEPHONE 617 366-9011 Office of Inspection & Enforcement Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 Attention:
Mr. Boyce H. Grier, Director
References:
(a)
License No. DPR-28 (Docket No. 50-271)
(b) USNRC Letter to VYNPC dated April 4, 1980; IE Bulletin 80-07
Subject:
Response to IE Bulletin 80-07; BWR Jet Pump Assembly Failure
Dear Sir:
Recent experiences at Dresden Unit 3, Quad Cities Unit 2 and Pilgrim indicate that hold-down beam assemblies and jet pump function can degrade during operation. Reference (b) requires certain actions to be taken by licensees of GE designed BWR-3 and BWR-4 facilities that are currently operating.
The following information i.s submitted in response to Reference (b):
B.1 Justification for Continued Operation Vermont Yankee has established the procedures for a daily surveillance of jet pump parameters which assures proper jet pump performance.
These procedures utilize established operational data bases with a daily surveillance program to provide an early indication of an impending jet pump disassembly.
Information received from General Electric indicates that an operational surveillance program of this type can provide a 7 to 13 day early warning of jet pump disassembly.
If it were determined that a jet pump beam had failed during normal operation, the plant would be brought to a cold shutdown condition.
Based on information obtained from plants that have experienced jet pump beam failures and General Electric, prior to detection, the recirculation flow through the jet pump nozzles decreases, which in turn causes a core power decrease.
Disassembly results in a minor flow reduction transient somewhat like a single recirculation pump trip event. Operation with t_c jet pump disasembled would create conditions similar to that during single loop operation; that is, back flow would be observed in a portion of the loop containing the disassembled pump and the other loop produces the majority of the core flow.
The jet pump disassembly will not impair naturcl circulation capabilities and thus the plant can be brought to a safe shutdown condition without benefit of recirculation drive flow.
1 Vermont Yankee is presently formulating plans necessary to allow visual 1
(television) and ultrasonic examinations to be conducted during the refueling outage presently scheduled to begin in September,1980.
j 80060605 0 j
Bnacd en inform tion contsin:d tbovs and that mida (vailabic by Ganaral Elsctric clong with implerentation of a cuitable surveillance progrrm, Vermont Yankee concludes that:
(1) Significant cracking of a jet pump beam which could lead to a jet pump disassembly can be detected.
(2) Jet pump beam cracks do not involve a significant increase in the probability of occurrence or consequences of accidents previously considered and they do not involve a decrease in the safety margin during postulated accidents.
(3) There is reasonable assurance that the health and safety of the public will not be endangered by continued operation until the jet pump beams can be inspected at the next scheduled refueling outage.
B.2 Surveillance Program The surveillance program suggested by Bulletin 80-07 was initiated within 10 days following receipt of this bulletin. We feel confident that this augmented surveillance program improves our ability to identify jet pump degradation or failure.
B.3 Reactor Operation If it is determined that a jet pump is inoperable or significantly degraded, the reactor will be shut down in accordance with the revised statien operating procedures.
B.4 Procedures Plant procedures have been reviewed and revised as necessary to ensure that station operators have adequate instruction regarding identification and response to jet pump failure.
We t ru s t the above supplied information is satisfactory; however, should you desire any additional information, please contact us.
Very truly yours,
VERM0 T YANKEE NUCLEAR POWER CORPORATION L. H. Heider Vice President COMMONWEALTH OF MASSACHUSETTS)
)ss COUNTY OF WORCESTER
)
Then personally appeared before me, L. H. Heider, who, being duly sworn, did state that he is a Vice President of Vermont Yankee Nuclear Power
-Corporation, that he is duly authorized to execute and file the foregoing request in the name and on the behalf of Vermont Yankee Nuclear Power Corporation, and that the statements therein are true to the best of his knowledge and belief.
HK Robert H. Groce Notary Public My Commission Expires September 14, 1984