ML20236F599
| ML20236F599 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 06/26/1998 |
| From: | Leach D VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 50-271-97-201, BVY-98-89, IEB-88-004, IEB-88-4, NUDOCS 9807020240 | |
| Download: ML20236F599 (3) | |
Text
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,[
VERMONT YANKEE y
NUCLEAR POWER CORPORATION 1' 5 Old Ferry Road, Brattleboro, VT 05301-7002 8
(802) 257-5271 June 26,1998 BVY 98-89 United States Nuclear Regulatory Commission I
- ATTN: Document Control Desk'
{
Washington, DC 20555
References:
(a)
Letter, USNRC to VYNPC, Vermont Yankee Design Inspection, Report No. 50-271/97-201, NVY 97-130, dated August 27,1997 (b)
I2tter, VYNPC to USNRC, Reply to Inspection Report 50-271/97-201, BVY 97-138, dated October 27,1997 (c) letter, VYNPC to USNRC, Supplemental Response to Bulletin 88-04, BVY 97-179, dated December 31,1997 i
l
Subject:
Vermont Yankee Nuclear Power Station License No. DPR-28 (Docket No. 50-271)
Final Disposition of Bulletin 88-04 In Reference (b), Vermont Yankee indicated a revised response to IEB 88-04 would be provided to specify additional plans and schedules to resolve the issues described in your Inspection Report (Reference a), concerning the installed Residual Heat Removal (RHR) and Core Spray
. CS) pump minimum flow capability. In Reference (c), Vermont Yankee provided an action
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plan for resolving the minimum flow concerns for the RHR and CS systems. This letter serves I
to provide the results of the four (4) actions' communicated in Reference (c) and constitutes our disposition of IEB 88-04 issues.
Vendor Acce== ment of Pumo Operability
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Our pump vendor, Sulzer Bingham (S/B) was requested to evaluate and verify operability of the d CS/RHR pumps for a number of minimum flow scenarios. It was Vermont Yankee's belief that the pumps would operate satisfactorily at the original General Electric specified minimum flow values, consistent with our current operating practices. The vendor has re-assessed pump.
minimum flow requirements, taking into account the vibration data taken during original and recent pump minimum flow operation. Based upon the scenarios provided to S/B and the
- resultant information provided back from S/B, the CS and RHR procedures have been revised to reflect the current pump minimum flow requirements.
9807020240 PDR ADOCK 71 0
VERMONT YANKEE NUCLEAR POWER CORPORATION Page 2 ef 3 l
Flow Instrumentation Modification u
l Vermont Yankee committed to the development of a design change to upgrade the CS and RHR L
flow instrumentation with safety class, environmentally qualified (EQ) instrumentation, which could be used by operators to assia in any necessary manual actions. The design change included all.CS and RHR flow instrumentation requirements to address the pump minimum flow-issue as well as ECCS suction strainer and in-service testing issues. The safety class and EQ instrumentation was installed during our recently completed Cycle 20 refueling outage.
CS and RHR System Modifications Vermont Yankee committed to develop a design change to modify the controls for the CS full flow test valves to allow operators to open the valves when an accident signal is present, if
=~~~y. The modification allows bypassing the continuous close signal that the valves receive l
due to an accident signal. The modification requires two distinct and separate operator actions l
in' order to open the valves when an accident signal is present to minimize the potential for
' operator error. This modification was installed during our Cycle 20 refueling outage, along with i.
the qualified instrumentation mentioned previously, to ensure adequate long term minimum flow can be provided simultaneously with requiled vessel flow.
As previously mentioned in Reference (c), the RHR system did not require modification other than the flow instrumentation upgrade. By utilization of the torus cooling valves and IPCI injection valves, operators have the ability to control required flow to the vessel, while ensuring
' adequate, long term minimum flow.
In Plant Testing A test procedure was developed and implemented to satisfy a commitment to the NRC to verify j
l the RHR minimum flow rate and to obtain vibration data at the minimum flow value and at other I
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flow rates. The test resulted in a measured minimum flow rate of greater than 350 gpm
' (original design value) and was consistent with the assumptions made in a Basis for Maintaining j'
Operation (BMO) in place at that time. The flow and vibration data taken on an RHR pump operating at minimum flow was forwarded to our pump vendor (Sulzer Bingham) in support of
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their evaluation / conclusions of RHR minimum flow requirements previously summarized in this letter.'
The results of the actions summarized in this letter provide our final disposition of the issues pertaining to IEB 88-04 as committed to in earlier correspondence. It is concluded that with these actions taken, along with procedural enhancements, that the RHR and CS minimum flow requirements are adequately addressed for long term pump operation for all modes of operation.
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A A
O ER CORPORADON
- BVY 98-89 Page 3 of 3
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Should you have any questions or require any additional information regarding this issue, please contact this office.
j.
Sincerely, l
VERMONT YANKEE NUCLEAR POWER CORPORATION N
W/f Don M.
h Vice President, Engineering cc:
USNRC Region 1 Administrator N 8AN04 USNRC Project Manager - VYNPS _
USNRC Resident Inspector '?YNPS NOTAR)
Vermont Department of Public Service l
FUBUC A
STATE OF VERMONT
)
q
)ss
- 00g, WINDHAM COUNTY
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Then personally appeared before me, Don M. Ieach, who, being duly sworn, did state that he is Vice President, Engineering of Vermont Yankee Nuclear Power Corporation, that he is duly authorized to execute and file the foregoing document in the name and on behalf of vermont yankee Nuclear Power Corporation, and that the statements therein are true to the best of his j
knowledge and belief.
L Y b $2L Safly A. Simdstdun, Notary Public l
My Commission Expires Febmary 10,1999 I:
I c
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