ML19296D451
| ML19296D451 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 02/26/1980 |
| From: | Moody D Maine Yankee |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| MWY-80-31, NUDOCS 8003040606 | |
| Download: ML19296D451 (2) | |
Text
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TURNPIKE ROAD (RT. 9)
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ENGINEERING OFFICE WESTBORO, MASSACHUSETTS 01581 Q
617-366-9011 B.3.2.1 MWY 80 31 February 26, 1980 United States Nuclear Regulatory Commission Was hington, D. C.
20555 Attention: Office of Nuclear Reactor Regulation
References:
(1)
License No. DPR-36 (Docket No. 50-309),
(2)
MYAPC letter to USNRC, dated January 30, 1980, Maine Yankee Reportable Occurrence #80-001/0lL-0, (3)
MYAPC letter to USNPC (WMY 78-62), dated June 26, 1978, Proposed Change #64, (1)
MYAPC letter to USNRC,(WMY 79-143), dated December 5, 1979, YAEC-1202, " Cycle 5 Core Performance Analysis", Yankee letter, WMY 79-143, Proposed Change #73.
Gubject:
Low Power Steam Line Break Dear Sir Reference (2) identified an incorrect postulation in the low power steam line break analyses submitted in References (3) and (4) for Maine Yankee, involving the post reactor trip positioning of-P.he feedwater regulating valve bypass valves. Reanalysis of the event resulted in a return-to-power tr ans lent.
A return to power is not necessarily a concern with respect to the health and safety of the public; however, preventing a return to power post stea? line break has been a licensing criteria imposed by Maine Yankee as a s imple means for evaluation. Furthermore, the potential for a return to power is based on the licensing analysis with inherent conservative assumptions and worst case parameters; i.e., stuck rod, end of cycle (EOC) most negative moderator temperature, coefficient with uncertainties, double-ended guillotine break, one HPSI, etc.
Since the problem is associated with the EOC steam line break there is no impact on the Beginning-of-Cycle 5 operation.
In order to resolve this issue the setpoint on the bypass feed m ter valve override position will be rrodified such that the post trip feedwater flow is low enough to show acceptable results for the zero power steam line break but high enough to provide sufficient feedeter to remove decay heat following a reactor trip from full power.
80030 40g
e United States Nuclear Regulatory Commission February 26, 1980 Office of Nuclear Reactor Regulatiot Page 2 As part of the startup test program for Cycle 5, Maine Yankee will conduct a test to verify the correct positioning of the feeduter regulating bypass valves to limit pos t trip feedeter flow.
Furthermore, Maine Yankee commits to providing a revised steam line break analysis based on the modified feeduter bypass valve setpoint within 30 days following Cycle 5 startup.
We trust this information adequately addresses your concerns; however, should you desire additional information, feel free to contact us.
Very truly yours, MAINE YANKEE ATOMIC POWER COMPANY D.
E. Moody 0
Manager of Operations DD4/ dis e
.