ML20062J192

Forwards Response to IE Bulletin 82-02, Degradation of Threaded Fasteners in RCPB of PWR Plants. Improved Design Gasket Is Onsite & Ready for Use to Repair Reactor Coolant Pump

ML20062J192
Person / Time
Site:	Oconee
Issue date:	07/29/1982
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
REF-SSINS-6820 IEB-82-02, IEB-82-2, NUDOCS 8208160291
Download: ML20062J192 (3)

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Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303

Subject:

Oconee Nuclear Station IE Bulletin 82-02

Dear Sir:

As specified in IE Bulletin 82-02 dated June 2, 1982, please find attached a response to Item 3. Other actions are being performed as specified in the Bulletin and will be reported at the appropriate time.

I declare innder penalty of perjury that the statements set forth herein are true and correct to the best of my knowledge, executed on July 29, 1982.

Ver truly yours,

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William O. Parker, Jr.

JFN/php Attachment cc: Mr. W. T. Orders NRC Resident Inspector Oconce Nuclear Station Mr. Philip C. Wagner Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 8208160291 820729 ppR ADOCK 05000 ff/l

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Attachment Item 3 NRC Information Notice Nos. 80-27 and 82-06, and similar INPO (Institute of Nuclear Power Operations) correspondence (with recommendations) have been issued in regard to corrosion problems associated with bolts / studs in RCPB closures (INP0/NSAC SER 81-12). To assist the Nuclear Regulatory Commission in its ongoing review and assessment of the scope of the problem you are asked to provide the following information for closures and connections within the scope of this bulletin:

a. Identify those bolted closures of the RCPB that have experienced leakage, particularly those locations where leakage occurred during the most recent plant operating cycle. Describe the inspections made and corrective measures taken to eliminate the problem. If the leakage was attributed to gasket failure or its design, so indicate.

b. Identify those closures and connections, if any, where fastener lubricants and injection sealant materials have been or are being used and report on plant experience with their application particularly any instances of SCC of fasteners. Include types and composition of materials used.

Response

Item 3a: The bolted closures (that are a part of the reactor coolant pressure boundary where leakage problems have been experienced) have been the once through steam generator (OTSG) manways and the Unit 2 and 3 (Bingham) reactor coolant pumps (RCP) main closure flange. The OTSG manways are inspected as l a part of the RB fins 1 tour before a start-up from cold shutdown. If leakage l is detected, it is repaired before proceeding with unit heat-up. Because of i .the scope of the work that would be necessary to repair the leak in the RCPs with new closure gasket, other methods, as will be discussed later, are being used to slow down the leakage rate. It appears that the design of the gaskets currently installed in the Unit 2 and 3 RCPs is possibly deficient and the possible reason for the leakage. An improved design gasket is onsite ready for

, use the next time there is an opportunity to repair the RCPs.

l Item 3b: Almost all RCPB bolted closures have had some type of thread lubricant l applied to it. The Duke Power Company Power Chemistry Materials Guide specifies what thread lubricants can be used. Typically, Molykote G-Rapid spray,NEVER-SEEZ Pure Nickel, and Felpro N-5000 are the most widely used lubricants. Furmanite F-500 and F-700-N have been used as sealants on four valves and four RCPs as

, follow: Valve 3CF-1 (NSM ON-983), valve 2RC-68 (NSM ON-1594), valve ILP-1 (NSM ON-

! 1936), valve 3HP-152 (NSM ON-1997), RCPs 2A1, 2A2, 2B2, and 3Al. Valve 3HP-152, l which is a Velan stop check valve, is the only valve that has not been dis-l assembled, furmanite removed, repaired, and reassembled. The RCPs had the furmanite injected into an annulus above the outermost of the two closure gaskets and none cave been disassembled for repair after the furmanite injection.

The only known problem with stress corrosion cracking (SCC) on RCPB bolting occurred on Unit 3 on the 3A OTSG lower primary manway (reported in Licensee Event Report No. 287/80-11). As was stated in a later report, Molykote G-Rapid

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was suspected of having caused the SCC although this has not been proven as being the main cause.

A check would have to be made with each manufacturer to ensure that the com-position of each product is nonproprietary. However, Duke Power Company is not as concerned about the composition as ensuring that the materials do not centain known contaminants. Lubricants and scalants are tested by Duke Power and classified as to where each can be used in accordance with the Duke Power Company Power Chemistry Materials Guide. Of the materials listed above, the Molykote G-Rapid spray lubricant is of potential concern due to its high sulphur content. While the composition of the material as formulated is not of concern, there is some question regarding the potential for degradation of the material ~

in a specific aqueous environment.

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