ML20210S401
| ML20210S401 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 09/03/1997 |
| From: | Graham P NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEIN-96-048, IEIN-96-48, NLS970164, NUDOCS 9709090431 | |
| Download: ML20210S401 (4) | |
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NLS970164 September 3,1997 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 2055$ 0001 Gentlemen:
Subject' improved Focus on Safety Cooper Nuclear Station, NRC Docket 50-298, DPR-46 The management at Cooper Nuclear Station (CNS) believes that it has been proactive and effective in dealing with longstanding equipment and programmatic issues. Many of these issues are not unique to CNS and have challenged the industry for some time. We believe our response to these issues is indicative of an organization that has matured rapidly over the last two years in the meas of engineering and operations and reflects an organization that has developed a strong focus on nuclear safety. These conclusions are supported by the following examples.
In the last quarter of 1996, the plant continued to respond to a periodic double pumping ano.maly from the drywell floor drain sump. This problem periodically surfaced and had been an unexplained issue for approximately ten years. The engineering staff at CNS resolved to correct this longstanding probkm and subsequently determined that the problem had been introduced during the recirculation piping replacement outage in 1985, The s+a4Tdeveloped a modification to correct the malfunctioning drain system and the problem was corrected during our last refueling outage. While determining additional actions that might be necessary to further troubleshoot this problem in the event that the modification was not effective, management directed that cameras be installed in the drywell to enhance leak detection capabilities. This additional aid, while not necessary to correct the floor drain pumping problem, was instrumental in locating floor drain leakage that developed shortly after startup. This installation allowed us to quickly locate the source, plan repair packages in advance, and repair a problem that could have otherwise caused a shutdown transient on the plant.
During this same refueling outage, our engineering organization similarly took an aggressive approach in developing and implementing the torus suction strainer modification. CNS management considered this modification to be a significant element in resolving a concern that needed to be addressed. This decision placed additional stress on an engineering organization which has been struggling to improve its performance over the last several years and, because of [
its timing, threatened to adversely impact the outage schedule. While the final NRC/BWROG 1
resolution of the debris generation / transportation issue has yet to be achieved, we decided that installing the modification (rather than asking for a deferment) was the right thing to do from a g
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nuclear safety perspective. As a result, this modification has been successfully installed and tested and now provides CNS addhional assurance of Ememency Core Cooline System (ECCS) operability' 970M90431 970903 hi i lllh.
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s NLS970164 September 3,1997 Page 2 of 3 While the recent refueling outage provided CNS the opportunity to address many longstanding issues, others resurfaced. For example, all of the safety relief valves failed to ptss their as-found testing criteria. This problem has existed at CNS for years and has been a longstanding issue in the industry as well. Although we were not able to definitively resolve the concern during this outage, our engineering evaluations support continued operation within limits for at least ten montbc following startup. Consequently, as described in LER 97-002, we have committed to a mid-cycle outage to take corrective action to ensure our safety relief valves stay within allowable specifications (e.g., pilot valve seat material replacement).
During the outage we also discovered a potential concern where there was inadequate margin to assure that some motor starter contacts would pick up during analyzed undervohage conditions.
Immediate actions were taken to resolve this specific issue. This finding was a result of a comprehensive and on-going self-initiated upgrade of our electrical distribution system analysis to ensure potential concerns are identified and corrected.
Our focus on safety has not been totally inward directed as our focus on industry experience is also much improved. Prior to the refueling outage, we evaluated difliculties being experienced at another utility with similar diesel generators for potential applicability to CNS. We sent our system engineer to evaluate a concern with cylinder liners and expanded our own diesel generator inspections to ensure that we did not share similar concerns.
In response to information Notice 96-48, " Motor-Operated Valve Performance issues," CNS engineering evaluated our situation against potential worst-case scenarios and took proactive measures to implement a valve modification to address motor sizing concerns.
We are very proud of our performance over recent months. Continued process improvements have resulted in reductions in engineering backlogs. Our refueling outage gave us opportunities to reinforce management expectations relative to the rigor to be applied in the Control Room and in the conduct of routine business. As a result, our outage was one of our most focused and safe in many years. While improvements in our safety focus are demonstrated by the results outlined above, we recognize that further and continued performance improvement is necessary to achieve our goals.110 wever, we are confident we will achieve our goals because we are committed to safety and are actively pursuing problems and their resolution.
Sincerely, PML P. D. Graham Vice President of Nuclear Energy
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NLS970164 i
- Sel tember 3,1997 Page 3 of 3 cc: Regional Administrator USNRC - Region IV Senior Project Manager USNRC - NRR Project Directorate IV 1 1
Senior Resident inspector USNRC NPG Distribution b
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l ATTACHMENT 3 LIST OF NRC COMMITMENTS l
Correspo,ndence No: NLS970164 The following table identifies those actions committed to by the District in this document. Any other actions discussed in the submittal represent intended or planned actions by the District.
They are descrioed to the NRC for the NRC's information and are not regulatory commitments.
Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.
COMMITTED DATE COMMITMENT OR OUTAGE None.
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PROCEDURE NUMBER 0.42 l
REVISION NUMBER S l
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