05000352/FIN-2017007-01
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Finding | |
|---|---|
| Title | Failure to Document Technical Basis for Service Temperature Changes for Limitorque Motor Operated Valve Limit Switches |
| Description | The inspection team identified a Green non- cited violation of Title 10 of the Code of Federal Regulations (10 CFR) 50, Appendix B, Criterion III, Design Control, because Exelons design control measures did not provide for verifying or checking the adequacy of design of the inboard high pressure coolant injection ( HPCI ) steam supply primary containment isolation valve from environmental effects. Specifically, as part of extending component life for license renewal, Exelon changed the normal service temperature of the valve limit switches from 145F to 135F without suff icient technical justification. Exelon documented this issue in their corrective action program as issue report 4076939, and changed the qualified life of the limit switches back to 41 years. Exelon also plans to evaluate the impacts of process fluid tem perature on the qualified life of the limit switches. The inspection team determined that the performance deficiency was more than minor because it was associated with the design control attribute of the Barrier Integrity Cornerstone and adversely affected the cornerstone objective of ensuring that physical design barriers (containment) protect the public from radionuclide releases caused by accidents or events. Specifically, using incorrect service temperatures resulted in inappropriately extending qualified service life of the HPCI inboard containment isolation valve limit switches . The inspection team evaluated this finding in accordance with IMC 0609, Appendix A, The Significance Determination Process for Findings at Power, Exhibit 3, Barrier Integrity Screening Questions. The inspection team determined the finding was of very low safety significance (Green) because it was a design deficiency confirmed not to result in an actual open pathway in the physical integrity of reactor containment and did not involve an actual reduction in function of hydrogen igniters in the reactor containment. The finding had a cross -cutting aspect in the area of Human Performance, Design Margins, because Exelon did not evaluate issues to ensure that margins are carefully guarded and changed only through a systematic and rigorous process. Specifically, Exelon c hanged the service temperature for the Limitorque motor operated valves inside containment in 2014 that extended the qualified service life of the most limiting component beyond 60 years. [H.6] |
| Site: | Limerick  |
|---|---|
| Report | IR 05000352/2017007 Section 1R21 |
| Date counted | Dec 31, 2017 (2017Q4) |
| Type: | NCV: Green |
| cornerstone | Barrier Integrity |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21N |
| Inspectors (proximate) | C Bickett J Ayala K Mangan G Dentel |
| Violation of: | 10 CFR 50 Appendix B Criterion III, Design Control |
| CCA | H.6, Design Margins |
| INPO aspect | WP.2 |
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Finding - Limerick - IR 05000352/2017007 | ||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Limerick) @ 2017Q4
Self-Identified List (Limerick)
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