ML19296A223
| ML19296A223 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 02/14/1979 |
| From: | Moody D VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| WVY79-16, NUDOCS 7902210264 | |
| Download: ML19296A223 (2) | |
Text
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scvcNTY sETcN GROVE STREET RUTLAND.VEIO10 NT 05701 IMS B.3.2.1 REPLY TO-ENGINEERING OFFICE TURNPIKC RO AD WESTDORO. M ASS ACHUSETTS 01581 TELEPHONE 617-366 9011 February 14, 1979 WVY 79-16 Director, Division of Operating Reactors Office of Nuclear Reactor Regulation Nuclear Regulatory Commission Washington, DC 20555
Reference:
(1). License No. DPR-28 (Docket No. 50-271)
(2) USNRC letter to VYNPC dated February 8, 1979 (Bulletin 79-01)
Dear Sir:
Subject:
Environmental Qualification of Class IE Equipment Reference (2) requires that Vermont Yankee determine if certain types of stem mounted limit switches are used and located inside the containment.
It piso requires that Vermont Yankee report, within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, any items which are identified as not meeting the qualification cequirements for the service intended.
The results of our review indicate that we have certain limit switches that do not meet the environmental qualification criteria.
These limit switches are located on Main Steam Line Isolation Valves inside the pri-mary containment and are either Namco Models SL-3CM-7L or SL-3C-11L.
Of the seven unqualified switches identified, three provide an input to the Reactor Protection System and four are used for open indication only.
It should be noted that these switches were not identified as being environ-mentally unqualified in our review of NRC Bulletin 78-04.
Continued plant operation is justified for the following reasons:
a.
The Reactor Prote ction System input is required only to anti-cipate the pressure and flux transient which would occur if these Main Steam Isolation Valves should close during an oper-ational event. This function is not required to cope with a loss of Ccolant Accident.
Separate environmentally qualified sensors provide these inputs to the Reactor Protection System.
The closure of the redundant isolation valves outside the containment provide the identical anticipatory signals to the Reactor Protection System.
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The four switches that are used to provide Main Steam Isolation valve position indication only would not prevent the subject valves from achieving their isolation function during a Loss of Coolant Accident.
The redundant isolation valves outside the primary containment, including the associated instrumentation would be available to allow the Control Room operators to as-certain that containment isolation has been achieved.
In addi-tion, other Control Room indication is available to provide independent verification of main steam line isolation.
A detailed follow-up report will be provided within the required 14 days.
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. E. Moody' Manager of Operations DEM/fb 4
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