ML20077R671
| ML20077R671 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 08/19/1991 |
| From: | Murphy W VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BVY-91-76, NUDOCS 9108230266 | |
| Download: ML20077R671 (3) | |
Text
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4 VERMONT YANKEE NucnEAlt POWElt COltPOllATION
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Ferry Road. Brattleboro, VT 053017002 ENGINE G OF FICE H
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!M.h ?N (711 August 19, 1991 U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Attention:
Document Control Desk
References:
a)
License No. DPR 28 (Docket No. 50 271) b)
Letter, USNRC to VYNPC, NRC Safety System Functional Inspection Team Report 50 271/90 80, dated October 23, 1990
- c)
Reportable Occurrence - No. LER 9010, Supplement 1,-
November 16, 1990 d)
Letter, VYNPC to USNRC, Response to NRC Safety System Functional Inspection 50 271/90 80), Notice of Violations, BVY 90-119, dated (November 28, 1990
Dear Sir:
Subject:
Supplemental Response to NRC Safety System Functional Inspection, Notice of. Violations This letter provides supplemental information to Reference d) regarding proposed corrective actions for load testing the emergency diesel generators and withdraws our earlier request for additional NRC review of 50 271/90 80 03.
VIOLATION "PART 4.10 A.1.a of the Technical Specifications requires that each diesel generator shall be started and loaded once a month for sufficient time for the diesel engine and generator to reach equilibrium -temperature at exIsocted maximum emergency loading, not to exceed the continuous rating, to demonstrate operational readiness.
Contrary to the above, the diesel generators'were nsistently tested at loads lower than expected maximum pr-Jed in the Final Safety. Analysis Report, Section 8.5.3. - The under loading _
was caused by using a unity or 100% power factor during the test rather than usinsi a realistic value of 80 90% power factor.
Further, both the 4ovember 1988 and April 1990~ diesel generator loading. studies made by the licensee provided information that the diesel generator loading was substantially higher than the FSAR and the monthly surveillance. tests loading value."
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4 VCRMONT YANKCC NUCLC AR POWER CORPORATION U.S. Nuclear Regulatory Commission August 19, 1991 Page 2 y
BESPONSE As stated during telecons with NRC Region i Staff on 8/1/91 and 8/2/91 concerning Diesel Generator surveillance testing, Vermont Yankee will develop testing methods and procedures to perform monthly diesel generator surveillance testing with a VAR load equivalent to the maximum emergency load.
We will test this new surveillance method on our simulator and train the station operators during the tralning cycle scheduled to begin on 10/1/91 (LOR 91.4) so that on-or before the normal monthly diesel surveillance for December 1991, we will be able to commence the new test method.
VIOLATION "10CFR50, Appendix B,
Criterlon lil, requires that design control measures provide fer verif'f ng or checking the i
adequacy of the design.
The Vermont Yankee Operational Quality Assurance Manual, Section Ill, Design Control reciulres... 'the performance of proper design verification or cliecking by means of design reviews or alternate calculations by verifiers with the proper qualifications and the required level of responsibility for adequacy of design'.
Contrary to the above, an analysis was conducted,-Calculation VYC 791, to verify the adequacy of the safety related 480 voll motor control centers to orovide power to the attached loads.
The analysis concluded that the motor control centers were adequate y sized to suppl the necessary power of 481 amperen; however, the anal sia and the requireo verification revlew failed to recognize i at the electrical capacity of MCC-8A was limited by the feeder circuit breaker and cables to 400 amperes."
RESPONSE
in response to the 1990 NRC SSFI team queries, VY revised VYC 791 on
- August 15, 1990.. This revision evaluated the Im aact of MCC feeder cable size, feeder breaker trip ratings, and identified the lim ting factors affecting the ability of MCC 8A to supply emergency loads. The revised load schedule for MCC 8A showed that although the MCC load approached the long time feeder breaker trip setting, it was operable in the as found condition.
Time current curves for the MCC 8A feeder breaker were also developed in accordance with Vermont Yankee's relay coordination and protection
4 VERMONT YANKEE NUCLE AR POWER CORPORATION U.S. Nuclear Regulatory Commission August 19, 1991 Pago 3 quidelines.
Now breaker sottings woro provided to Vermont Yankoo personnel Jor their use on September 20, 1990, and the trip sotting was modiflod during the 1990 refueling outage. This change provided additional assurance that MCC 8A would supply its required emergency loads and protect the foodor cable.
Additionally, the load tables for MCCs BB, 9A, 9B, 90, and 9D were reviewed and revised to ensure that all omt gency loads were included.
The limiting factors (i.e., feedor cable or feodor breaker trip sottings) woro evaluated to ensure that the MCCs woro capable of supplying their required emergency loads.
No additional concerns with feodor circuit breakers or cables were identiflod.
Vermont Yankeo will continue the design basis reconstitullon efforts in the area of electrical distribution, as discussed in NUMARC 9012, Design Basis Program Guldelines sind in our previous response to this violation in Referenco d).
In this regard, we withdraw our request for further NRC revlow of this violation.
We trust the additional Information provided above adequately addrost.e; those issues: however, should you have any questions or desire additional information, please do not hesitate to contact us.
Respectfully, Vermont Yankoo Nuclear Power Corporation
' h wy W
Warren P.
rph Senior Vic rest o t, p ations cc:
USNRC Regional Administrator, Region l USNRC Resident inspector, VYNPC USNRC Project Manager, VYNPC
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