05000373/FIN-2017009-01: Difference between revisions
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| identified by = NRC | | identified by = NRC | ||
| Inspection procedure = IP 71153 | | Inspection procedure = IP 71153 | ||
| Inspector = J Benjamin, A Dunlop, C Phillips, L Rodriguez, K O | | Inspector = J Benjamin, A Dunlop, C Phillips, L Rodriguez, K O'Brien | ||
| CCA = N/A for ROP | | CCA = N/A for ROP | ||
| INPO aspect = | | INPO aspect = | ||
| description = In 1990, the licensee had reviewed and accepted the vendors weak link analyses that provided the upper torque and thrust limits for all safety-related ADDDGV in service at the station. This analysis documentedthat the 1E22-F004 and 2E22-F004 valve stems were the weak link valve components in the closing direction (i.e.,provided enough closing thrust, thevalve stems would be the firstcomponent to becomenonfunctional).Therefore, theclosed thrust limit forthe 1E22-F004 and 2E22-F004 valves was approximately 260,000 lbf. The licensee had set up the valves ina manner that would ensure that the valveswould have enough torque and thrust tooperate under design basis conditions while staying below the maximum weak link limits. Maintenance and test records showed that thelicensee consistently verifiedthat these two valves were setup and maintained within this design window. Typical as-found and as-left closed thrust limits ranged from approximately between200,000240,000 lbf.As described in the licensees failure analysis report and as discussed above, the licensee identified that the pressed-fitcollar could relax its pre-load when operating the valve well within the established maximum closed thrust limitations. The licensees failure analysis report estimated that approximately 130,000 lbf was necessary to shift the collar up and relax the pre-load. Therefore,theteam concluded that the licensees weak link analysis was inadequate based upon the 2E22-F004 valve failure and associated failure analysiswhich determined that the pressed-fitcollar was a weaker component as compared to the valve stem. The team did not identify an associated performance deficiencyfor the inadequate weak link analysis. This determination was based upon the weak link analysis originating from the vendor in 1990, licensees review of that analysis, and latent design issue that had not been previously identified within the industry until recently identified by the licensee.Additionally, the team did not identify a violation of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action. This determination was based, in part, that correcting the unknown stem collar pre-torque issueafter receiving the 10 CFR Part 21 Flowserve notification would not necessarily have identified and corrected the non-conforming inadequate weak link design control issue. Enforcement: Title10 CFR Part 50, Appendix B, Criterion III, Design Control, requires,inpart that measures shall be established to assure that applicable regulatory requirements and the design basis, as defined in 50.2, and as specified in the license application, for those structures, systems, and components to which this appendix apply are correctly translated into specifications, drawings, procedures, and instructions.Contrary to the above, since original plant construction, the licensee failed to ensure thatapplicable design basismaximumclosed thrust and torque valuesfor the safety-related Unit 1 and Unit 2 HPCS injection valves (1E22-F004, 2E22-F004)werecorrectly translatedinto specifications. Specifically, it was identified that the stem-to-wedgepre-torque credited within the design could relax by applying closed direction torque and thrust well within the specified design limitbecause that limit was based uponthe wrong weak link component. The loss of the stem-to-wedgepre-torque could subsequently break the wedge pin and result in stem-to-wedgethread degradation ultimately leading to valve failure.The NRC determined that issue was a Severity Level III Violation based upon Section6.1(c)(2) of the Enforcement Policy. Specifically, a system that is part of the primary success path and which functions or actuates to mitigate a design base accident or transient that either assumes the failure of or presents a challenge to the integrity of the fission product barrier not being able to perform its licensing basis safety function because it is not fully qualified.The NRC exercised enforcement discretion in accordance with Sections 3.10 of the Enforcement Policy and Section 3 of Part1 of the Enforcement Manual. Enforcement Policy Section 3.10 states that the NRC may exercise discretion for violations of NRC requirements by reactor licensees for which there are no associated performance deficiencies. This violation was entered into the Corrective Action Programas Issue Report3972901 and has been corrected by replacing the 1E22-F004 and 2E22-F004 valve stems with integral collars. | | description = In 1990, the licensee had reviewed and accepted the vendors weak link analyses that provided the upper torque and thrust limits for all safety-related ADDDGV in service at the station. This analysis documentedthat the 1E22-F004 and 2E22-F004 valve stems were the weak link valve components in the closing direction (i.e.,provided enough closing thrust, thevalve stems would be the firstcomponent to becomenonfunctional).Therefore, theclosed thrust limit forthe 1E22-F004 and 2E22-F004 valves was approximately 260,000 lbf. The licensee had set up the valves ina manner that would ensure that the valveswould have enough torque and thrust tooperate under design basis conditions while staying below the maximum weak link limits. Maintenance and test records showed that thelicensee consistently verifiedthat these two valves were setup and maintained within this design window. Typical as-found and as-left closed thrust limits ranged from approximately between200,000240,000 lbf.As described in the licensees failure analysis report and as discussed above, the licensee identified that the pressed-fitcollar could relax its pre-load when operating the valve well within the established maximum closed thrust limitations. The licensees failure analysis report estimated that approximately 130,000 lbf was necessary to shift the collar up and relax the pre-load. Therefore,theteam concluded that the licensees weak link analysis was inadequate based upon the 2E22-F004 valve failure and associated failure analysiswhich determined that the pressed-fitcollar was a weaker component as compared to the valve stem. The team did not identify an associated performance deficiencyfor the inadequate weak link analysis. This determination was based upon the weak link analysis originating from the vendor in 1990, licensees review of that analysis, and latent design issue that had not been previously identified within the industry until recently identified by the licensee.Additionally, the team did not identify a violation of 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action. This determination was based, in part, that correcting the unknown stem collar pre-torque issueafter receiving the 10 CFR Part 21 Flowserve notification would not necessarily have identified and corrected the non-conforming inadequate weak link design control issue. Enforcement: Title10 CFR Part 50, Appendix B, Criterion III, Design Control, requires,inpart that measures shall be established to assure that applicable regulatory requirements and the design basis, as defined in 50.2, and as specified in the license application, for those structures, systems, and components to which this appendix apply are correctly translated into specifications, drawings, procedures, and instructions.Contrary to the above, since original plant construction, the licensee failed to ensure thatapplicable design basismaximumclosed thrust and torque valuesfor the safety-related Unit 1 and Unit 2 HPCS injection valves (1E22-F004, 2E22-F004)werecorrectly translatedinto specifications. Specifically, it was identified that the stem-to-wedgepre-torque credited within the design could relax by applying closed direction torque and thrust well within the specified design limitbecause that limit was based uponthe wrong weak link component. The loss of the stem-to-wedgepre-torque could subsequently break the wedge pin and result in stem-to-wedgethread degradation ultimately leading to valve failure.The NRC determined that issue was a Severity Level III Violation based upon Section6.1(c)(2) of the Enforcement Policy. Specifically, a system that is part of the primary success path and which functions or actuates to mitigate a design base accident or transient that either assumes the failure of or presents a challenge to the integrity of the fission product barrier not being able to perform its licensing basis safety function because it is not fully qualified.The NRC exercised enforcement discretion in accordance with Sections 3.10 of the Enforcement Policy and Section 3 of Part1 of the Enforcement Manual. Enforcement Policy Section 3.10 states that the NRC may exercise discretion for violations of NRC requirements by reactor licensees for which there are no associated performance deficiencies. This violation was entered into the Corrective Action Programas Issue Report3972901 and has been corrected by replacing the 1E22-F004 and 2E22-F004 valve stems with integral collars. | ||
}} | }} | ||
Latest revision as of 23:25, 21 February 2018
| Site: | LaSalle  |
|---|---|
| Report | IR 05000373/2017009 Section 4OA3 |
| Date counted | Jun 30, 2017 (2017Q2) |
| Type: | Violation: Severity level Enforcement Discretion |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | J Benjamin A Dunlop C Phillips L Rodriguez K O'Brien |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| INPO aspect | |
| ' | |