ML20204D191

Part 21 Rept Re Potential Existence of Design Defect in Bingham/Willamette RHR Pumps Flow Capacity.Ge Will Perform Evaluation of Conditions.Operators Will Be Alerted in Writing to Miminize Time in Min Flow Mode

ML20204D191
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	03/20/1987
From:	Weigand J VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
REF-PT21-87, REF-PT21-87-071-000 FVY-87-34, PT21-87-071-000, PT21-87-71, NUDOCS 8703250444
Download: ML20204D191 (3)

Text

c VERMONT YANKEE NUCLEAR POWER CORPORATION RD 5 Box 169. Ferry Road, Brattleboro, VT 05301

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ENGINEERING OFFICE 1(,71 WORCESTER ROAD FRAMINGHAM, MASSACHUSETTS 01701 TELEPHONE 6174724100 March 20, 1987 U.S. Nuclear Regulatory Commission Office of Inspection & Enforcement Region I 631 Park Avenue King of Prussia, PA 19406 Attn:

Regional Administrator

References:

a)

License No. OPR-28 (Docket No. 50-271)

Subject:

Notification of Potential Existence of a Design Defect in Accordance with 10CFR21.21 In accordance with the provisions of 10CFR21, Section 21, we are hereby notifying you that we have obtained information indicating that a design defect may exist with respect to Bingham /Willamette pumps.

Enclosure I to this letter dccuments the details of this evaluation.

Should you have any questions regarding this matter, please do not hesitate to contact us.

Very truly yours, j

VERMONT YANKEE NUCLEAR POW-ORPORATION l

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J G. Weigand President and Chief Executive Officer l'

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-O' ENCLOSURE I COMPANY INFORMING Vermont Yankee Nuclear Power Corporation THE COMMISSION RD 5, Box 169

' Ferry Road Brattleboro, Vermont 05301 FACILITY Vermont Yankee Nuclear Power Station Box 157 Governor Hunt Road Vernon, Vermont 05354 COMPONENT Bingham /Willamette - RHR/CS Pumps (16x18x26 1 Stage CVIC/12x16x144 1 State CVD31 FIRM SUPPLYING Bingham Willamette COMPONENT 2800 NW Front Avenue Portland, Oregon 97210 NATURE OF DEFECT Vermont Yankee's RHR/CS pumps were originally purchased from Bingham /

Willamette in accordance with GE design specifications. The specification sti-pulated a minimum flow capability of 350 gpm and Bingham /Willamette supplied the pump in accordance with the specification.

Vermont Yankee was notified by Bingham /Willamette on November 13, 1986 that the minimum flow rates for the RHR pumps should be made higher than pre-viously indicated to Vermont Yankee. Specifically, the value for continuous operation (more than two hours of operation within any 24-hour period) should be 2700 gpm_and the value for intermittent operation (less than two hours of opera-tions within a 24-hour period) should be 2075.

As a result of this notification, Vermont Yankee initiated a PRO and its subsequent review. This review determined this matter does not pose a substan-tial safety hazard for Vermont Yankee and was not reportable per 10CFR50.73, but was potentially reportable under 10CFR21 Vermont Yankee, in cooperation with Bingham /Willamette and General Electric, has concluded that a substantial safety hazard does not exist at Vermont Yankee. This conclusion is based on the following information.

Bingham /Willamette defines " intermittent cperation" as lets than two hours of operation in a 24-hour period over the 40-year design life. This translates to a value of up to a total 29,200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation. Vermont Yankee has no significant accumulated time in the minimum flow operating mode to date (cther than successful pre-operational testing). Monthly surveillance testing does not utilize the minimum flow path for more than 15-30 seconds per month and there-fore is considered to be negligible with respect to the 2075 hrs allowable.

In the event of a snall break LOCA, RHR and Core Spray would be required to operate

n in the minimum flow mode fo; a maximum of four or five hours. Vermont Yankee's PRO evaluation estimated a total of 5-10 hours of operation in the minimum flow mode for the life of the plant. As can be seen, these operating durations are far below the 29,200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of operation that Bingham /Willamette considers to be in the " intermittent" operating range, and that sufficient operating times in the minimum flow mode for either the RHR or the Core Spray pumps would not be attained for recirculation cavitation failures to develop.

However, it is determined that this matter could potentially present a significant safety hazard at another facility, depending on the application of this manufacturer's pumps and the length of time that a pump would be required to operate in the minimum flow mode.

DATE OF INCIDENT Vermont Yankee was notified by Bingham /Willamette of this condition by a letter dated November 13, 1986.

The Potential Reportable Occurrence for RHR pumps was generated on November 21, 1986 and approved as not reportable on December 6, 1986. The PRO for Core Spray was generated on December 12, 1986 and approved as not reportable on December 29, 1986.

NUMBER OF COMPONENTS Vermont Yankee has four (4) RHR and two (2) Core Spray pumps of the design previously described.

CORRECTIVE ACTION As a result of the investigation concerr.ing pump operability, Vermont Yankee requested General Electric to perform an evaluation of the conditions.

Vermont Yankee has received a draft report from GE which substantiates our ori-ginal findings.

In addition, Vermont Yankee will inspect the pump internals of the RHR pumps.

If eny degradation is found, further evaluation will be pursued.

Vermont Yankee will also make a Nuclear Network entry delineating the con-ditions of this problem.

As an added precaution, Vermont Yankee will incorporate a caution statement into the appropriate procedures to alert the operators of the need to minimize t;me in the minimum flow mode.

RELATED ADVICE Our evaluation has determined that a significant hazard does not exist at Vermont Yankee because of our application of the pumps. However, it is felt that this matter could create a substantial safety hazard at another nuclear facility.

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