ML20151U140

Discusses Mod of Previous Commitment to Replace Feedwater Check Valve VFW-305 Resilient Seal to Correct Past Poor Performance.Commitment Should Be Incorporated Into Normal Preventive Maint Program

ML20151U140
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	08/17/1988
From:	Scott W Office of Nuclear Reactor Regulation
To:	Berry K NORTHERN STATES POWER CO.
References
NUDOCS 8808180414
Download: ML20151U140 (4)

Text

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jog UNITED STATES 8 o NUCLEAR REGULATORY COMMISSION 5 E WASHING TON, D. C. 20555 August 17, 1988 k.....

Docket No. 50-155 Mr. Kenneth W. Berry Director, Nuclear Licensing Consumers Power Company ,

1945 West Parnall Road Jackson, Michigan 49201

SUBJECT:

MODIFICATION OF PREVIOUS COMMITMENT TO REPLACE FEEDWATER CHECK VALVE (VFW-305) RESILIENT SEAL (TAC 68215)

In a letter dated May 25, 1983, Consumers Power Company (CPC) discussed adding an Anchor-Darling dual seat ten-inch check valve (VFW-305) to the feedwater line to correct the past poor performance of the feedwater check valve with respect to containment integrity. The letter stated that the new design was chosen to enhance the ability of the valve to seat with low pressure air applied. The letter also stated that CPC conducted an informal survey of four nuclear power plants using Anchor-Darling dual seat check valves in their feedwater systems and found that a failure had been caused by crud impingement on the soft seat. To alleviate the concern about soft seat failure, CPC committed to replacing the soft seat on the valve each refueling outage until performance determines that another frequency is appropriate.

! Ir your letter dated April 18, 1988, you pointed out that NRC IE Information l Notite No. 84-12, "Failure of Soft Seat Valve Seals," was issued about eight months after you installed VFW-305. That Information Notice was issued i be,ause of concern over failures of LaSalle County Nuclear Plant's dual seat valve seals, one of which failed at the vulcanized seam. You reviewed the performance of VFW-305, stating that local leak rate tests (LLRTs) improved since the June 1983 original installation, as follows:

o 07/84 as-found LLRT - leak rate 10.8% of the maximum allowable containtrent leak rate technical specification limit Original seat with vulcanized seal replaced after the LLRT by an Anchor-Darling provided seat with molded seal.

l o 10/85 as-found LLRT - leak rate 0.5% of the technical specification limit l Replaced seat with similar seat.

l l o 01/87 as-found LLRT - leak rate 1.008% of the technical specification i limit i

Replaced seat with similar seat. ,

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You stated your belief that the above leak rates are not excessive for a ten-inch check valve and indicate acceptable performance. In October 1985, the valve was subject to a successful containment integrated leak rate test, further indicating satisfactory performance of the seats.

You also stated that durometer testing of the resilient seat indicates that the hardness of the seal is relatively unchanged over the period of one cycle, with measurements from 69 to 73.5, as compared to the manufacturer's original record of 70. Additionally, you stated that your current information from the valve ganufacturer indicates testing of the seal material (Stillman compound) at 420 F revealed only slight swelling over a period of Ig months with no substantial degradation; your application is at about 375 F, which you feel should extend the period for similar performance.

Based on the review of the information in your letter dated April 18, 1988, the NRC staff finds that your May 25, 1983 commitment has been fulfilled.

Valve VFW-305 should be incorporated into your normal preventive maintenance program. Prudent testing of the valve and examination and replacement of its seats and seals should continue.

Sincerely, Signed by Thomas V. Wambach ftr/

Wayne E. Scott, Jr. , Project Manager Project Directorate III-1 Division of Reactor Projects - III, IV, V & Special Projects cc: See next page Distribution eDocket F3Te3 NRC & Lccal PDRs PDIII-1 gray file MVirgilio GHolahan WScott RIngram OGC-WF1 EJordan BGrimes ACRS (10)

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O You stated your belief that the above leak rates are not excessive for a ten-inch check valve and indicate acceptable performance. In October 1985, the valve was subject to a successful containment integrated leak rate test, further indicating satisfactory performance of the seats.

You also stated that durometer testing of the resilient seat indicates that the hardness of the seal is relatively unchanged over the period of one cycle, with measurements from 69 to 73.5, as compared to the manufacturer's original record of 70. Additionally, you stated that your current information from the valve ganufacturer indicates testing of the seal material (Stillman compound) at420FrevealedonlyslightswellingoveraperiodofIgmonthswithno substantial degradation; your application is at about 375 F, which you feel should extend the period for similar performance.

Based on the review of the information in your letter dated April 18, 1988, the NRC staff finds that your May 25, 1983 commitment has been fulfilled.

Valve VFW-305 should be incorporated into your normal preventive maintenance program. Prudent testing of the valve and examination and replacement of its seats and seals should continue.

Sincerely, tl 4 Wayne E. Scott, Jr., Project Manager Wv Project Directorate III-1 Division of Reactor Projects - III, IV, V & Special Projects cc: See next page

Mr. Kenneth W. Berry Consumers Power Company Big Rock Point Plant cc:

Mr. Thomas A. McNish, Secretary Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201 Judd L. Bacon, Esquire Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201 Mr. Thomas W. Elward Plant Manager Big Rock Point Plant 10269 U.S. 31 North Charlevoix, Michigan 49720 Mr. Bud Heeres County Commissinner 303 Sheridan Charlevoix, Michigan 49720 Office of the Governor loom 1 - Capitol Building Lansing, Micnigan 48913 Regional Administrator, Region III U.S. Nuclear Regulatory Commission 199 Roosevelt Road Glen Ellyn, Illinois 50137 Nuclent Facilities and Environmental Monitoring Section Office Division of Radiological Health P. G. Box 30035 Lansing, Michigan 48909 U.S. Nuclear Regulatory Commission Resident Inspector Office Big Rock Point Plant 10253 U.S. 31 North Charlevoix, Michigan 49720 t

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