ML20092A714
| ML20092A714 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 02/07/1992 |
| From: | Kovach T COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9202100252 | |
| Download: ML20092A714 (4) | |
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"J W'7 Downers Grove, Illinois 60515 February 7,1992 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
Subject:
LaSalle County Nuclear Station Units 1 and 2 Response t0 Notice of Violation Inspection Report Nos. 50 373/91023; 50 374/91023 NRC Docket Nos. 50-373 and 50-374 tv
Reference:
Brent Clayton letter tc Cordell Reed dated December 24,1991 transmitting NRC Inspection Report 50-373/91023; 50-374/91023 Enclosed is Commonwealth Edison Company's (CECO) response to the subject NOV) which was transmitted with the referenced letter and Notice of Violation (The NOV cited one Severity Level IV violation. The violation inspection Report.
concerned the failure to promptly identify and correct the root causes of the problems which resulted in degradation and failure of emergency _ diesel generator (EDG) air start check valves. CECO's response is provided in the following attachment, if your staff has any questions or comments concerning this letter, please refer them to Annette Denenberg, Compliance Engineer at (708) 515-7352.
Very truly yours, Nuclear Lid. 6vach
.J fnsing Manager Attachmso cc:
A. Bert Davis, NRC Regional Administrator - Rill B. Siegel, Project Manager - NRR
. D, Hills, Senior Resident inspector gon oocsosooga g,
9202100252 920207 I
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RESPONSE TO LEVEL IV VIOLATION i
INSPECTION REPORT l
50 373/91023;50 374/91023 ATTACHMENT A
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VIOLATDON: in 073/91023-01 I
Appendix B Criter5n XVI of the Code of Federal Re0ulations. Title 10 pari 50, lequires measures to be esteblished to essure that conditions adverse to i
quality such as failures and malfunctions are promptly identified and correr tad.
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Comu
- the above, the licensee failed to aromptly identify and correct the
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root causes of the problems, which resulted n degradation and failure of Emergency Diesel Generator Air Start check valves from the period April 23, 1960, to November 18,1991.
This is a Severity Level IV violation (Supplenient 1).
REASON FOR THE VIOLATION:
- Commonwealth Edison acknowledgss the violation.-The violation involved the f ailure to identify a trend and subsequently perform a root cause failure analysis of a degrading condition,i.e. the corrosion and wear of check valves associated with the EDG air stari systems. The inspection repor1 discussed problems on five (5) check valves in the EDG air start systems. However, only three (3) of the valves are actually in the air start systems: the remaining two (2) valves,1DG030 and 2DG036, are the Low Pressure Core i
valves are of the(LPCS) motor cooler outlet check valves. Although the LPCS Spray Systems i
came model and manufacturer as most of the air start check valves, these valves pass cooling water drawn from the lake instead of air.
Commonwealth Edison has reviewed documentation dating back to March 1990. Based upon this review, it was determined that the degraded check valves did not affect the safety function of eith r the EDGs or the LPCS nize a weakness in the motors. However, Commonwealth Edison does recog/.. ~alves.
lack of root cause trending failure analysis of the che.
Administrative and programmatic controls should brav Jen more explicit in their direction, thereby identifying the need for the Otauon to perform a root cause failure analysis and follow up corrective actioii.
CORRECTIVE STEPS TAKEN AND HESULTS ACHIEVED:
Valves 2DG049B and ODG023A were disassembled, inspected, and replaced in Novembe'1991 via Nuclear Work Request's LO8877 and L11779. Acoustic diagnostic testing was performed on all remaining EDG air start systern check valves. All air start systems were found to be operable.
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CORRECTIVE STEFS TAKEN AND RESULTS ACHIEVED: (Continted)
A maintenance Problem Analysis Data Sheet (PADS) was Initiated. It was concluded that the probable root cause of the valve internals bein0 moist and corroded was due to a higher than acceptable molsture content in the air start systems. Also, the probable root cause of the valve body gouging was due to reciprocating pulsations produced by the air compressors, coupled with the design of the check valves.
The Unit 1 LPCS motor cooler outlet check valve (1DG036) was disassembled, ins aected, and cleaned during the refueling outage (L1R04) in 1991 y a Nuclear Work Request LO1542. The check valve spring was also replaced. The Unit 2 LPCS motor cooler outlet check valve (2DG036) is being disnssembled, inspected, and maintenance 3erformed as aaplicable during the current refueling outage (L2R04) via 9uclear Work Request LO8883.
A maintenance PADS concluded that the probable root cause of the valve internals being corroded was due to the chemistry of the LPCS motor cooling water. Prior to start up from LiR04 in 1991, a chemical addition system was added to treat the lake water used in the service water system. This system was added in response to Generic Letter 8913, and is ex3ected to mitigate check valve fouling caused by poor water quality. S nce the system has been in operation for only a short time, measurable benefits are yet to be realized.
CORREC11VE STEPS TO AVOlD FURTHER VIOLATONS:
Administrative procedures LAP 300 30, Check Valve Preventive Maintenance Program and LAP 300 7, Preparation and Control of Nuclear Work Requests, will be revised to enhance the direction given for the initiation of root cause failure analysis documentation. The LAP revisions are expected to be completed by May 31,1992.
i Maintenance Memorandums #6, Review of Total Job Management for Equipment Failure Trends, and #27, Analysis of Maintenance Problems, will be revised to enhance the trending of equipment and the direction given in the performance of a PADS for priority systems and components. The Maintenance Memorandum revisions are expected to be completed by May 31,1992.
Training on the revised Administrai,ve Procedures and Maintenance Memorandums for appropriate personnells expected to be performed by May 31,1992.
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I CORRECTIVE STEPS TO AVOID FUHTliER VIOLATIONS: (Continued)
- Nuclear Work Requests have been wtitten for the disassembly and inspection of the remaining EDG air start system check valves.
Disassembly and inspection is expected to be completed by May 31, 1992. Additionally Nuclear Work Requests have been written for the inspection and verification of proper operation for each of the EDG air start system's dryers. These inspections will be scheduled in accorc ance with routine station work planning practices and are expected to be completed by May 31,1992.
The disc from the Unit 2 LPCS motor check valve (2DG036) will be sent order to determine the root cause of the corrosion.ysis Department, in to Commonwealth Edison's System Materials Anal Acoustic diagnostic testing of check valves in the EDG air start systems and LPCS motor coolers will be performed on a semi annuni basis, so that data may be compiled and trended. The frequency of this testing may be adjusted as deemed necessary by future evaluations.
DATE WHEN FULL COMPLlANCE WILL BE ACHIEVED:
Full compliance will be achleved by May 31,1992, when the identiflod administrative and programmatic controls have been revised.
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