ML18153A317

Provides Util Actions Completed to-date & Update of Action Re part-length Control Rod Drive Mechanism Housing

ML18153A317
Person / Time
Site:	Surry, North Anna
Issue date:	08/14/1998
From:	Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
98-480, GL-97-01, GL-97-1, NUDOCS 9808200245
Download: ML18153A317 (2)

Text

e VIRGINIA ELECTRIC AND PowER CoMPANY RICHMOND, VIRGINIA 23261

~ ,* August 14, 1998 United States Nuclear Regulatory Commission Serial No.: 98-480 Attention: Document Control Desk NLOS/ETS R1 Washington, DC 20555-0001 Docket Nos.: 50-338/339 50-280/281 License Nos.: NPF-4/7 DPR-32/37

Dear Sir:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 SURRY POWER STATION UNITS 1 AND 2 PART-LENGTH CONTROL ROD DRIVE MECHANISM HOUSING LEAKAGE ACTION PLAN UPDATE In a letter dated April 14, 1998 (Serial No 98-171A), Virginia Electric and Power Company (Virginia Power) provided a preliminary action plan to address a leak identified in a dissimilar metal weld in a part-length control rod drive mechanism (CROM) housing at Prairie Island Nuclear Station for both Surry and North Anna Power Stations. Virginia Electric and Power Company continues to be actively involved in the Westinghouse Owners Group (WOG) activities associated with the part-length CROM housing weld failure evaluation and proposed corrective actions. This letter provides Virginia Power's actions completed to-date and an update of our action plan. This action plan is based on the WOG activities and the ultrasonic examination results to-date.

Surry Unit 1 (March 1998 Maintenance Outage)

Due to the length of the outage, the timing of the identification of this issue, as well as the limited examination experience and design information gained at that time, a "best effort" visual inspection was performed on the reactor vessel head and penetration area from the missile shield area during the maintenance outage. This inspection was only capable of detecting steam or boron deposits on the visually accessible portions of the head and penetration area. There were no indications of a leak identified during this inspection effort.

North Anna-Unit 2 Spring-*1998-Refueling 0utage ***

• During the refueling outage, four of the five part-length CROM housings were cut and capped. The fifth part-length CROM housing containing the reactor head vent dissimilar ((JJ&/

metal weld was ultrasonically (UT) inspected and found fully acceptable. The dissimilar metal welds in the four removed part-length CROM housings were ultrasonically examined and no indications were identified. These examination results are consistent with the industry examination results to-date.

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e e Future Refueling Outages for North Anna Unit 1 and Surry Units 1 and 2 (Scheduled for Fall 1998, Fall 1998, and Spring 1999, Respectively)

Based on the status of the WOG investigation, the industry inspection experience gained to-date and_the assessment performed by Westinghouse for the WOG, Virginia Power does not plan to perform any additional ultrasonic examinations of the part-length CROM housings. Consistent with our response to Generic Letter 97-01, we will continue to perform an augmented inspection (i.e., visual inspection of the accessible areas on the top of the reactor vessel head with insulation in place) of the reactor head area of each unit during scheduled refueling outages to identify any boric acid deposits.

Heightened Awareness to Reactor Coolant System Leakage Consistent with industry experience and part-length CROM housing examination results to-date, Virginia Power will continue to monitor RCS leakage in accordance with the Technical Specifications' required frequency. Station management and the operating staff recognize the significance of closely monitoring RCS leakage. RCS leakage is evaluated by various, diverse means to ensure that any increase would be promptly identified and applicable corrective actions would be taken in a timely manner.

Should you have any questions or require additional information, please contact us.

Very truly yours, James P. O'Hanlon Senior Vice President - Nuclear Commitments made in this letter: None cc: U.S. Nuclear Regulatory Commission Region II Atlanta Federal Center 61 Forsyth Street, SW Suite 23T85 Atlanta, GA 30303-3415 Mr. M. J. Mor-gan NRC Senior Resident Inspector North Anna Power Station Mr. R. A. Musser NRC Senior Resident Inspector Surry Power Station