ML16264A036
| ML16264A036 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 09/20/2016 |
| From: | John Klos Plant Licensing Branch IV |
| To: | Energy Northwest |
| Klos J, DORL/LPLIV-1, 415-5136 | |
| References | |
| CAC MF8302 | |
| Download: ML16264A036 (17) | |
Text
License Amendment Request for One-Time 7 Day Extension of Completion Time for TS 3.5.1.A, 3.6.1.5.A, and 3.6.2.3.A Energy Northwest September 22, 2016
Presentation Outline Proposed Change
Reason for Request
Precedent RHR System Modes of Operation LAR Approach Technical Evaluation Conclusion 2
Proposed Change Revise the completion time specified in Columbia Generating Station (Columbia) Technical Specification (TS) 3.5.1.A, 3.6.1.5.A, and 3.6.2.3.A, by adding a footnote for restoring residual heat removal (RHR) Train A to each of the required actions to allow a one-time 7 day extension (14 day completion time).
The proposed change also deletes a footnote associated with TS 3.5.1.A, 3.6.1.5.A, and 3.6.2.3.A which expired at 05:00 PST on February 9, 2015.
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Proposed Footnote The Completion Time that one subsystem of RHR (RHR-A) can be inoperable as specified by Required Action A.1 may be extended beyond the 7 day completion time up to 7 days to support restoration of RHR-A following the modification activity governed by EC 14635. Upon successful restoration of RHR-A, this footnote is no longer applicable.
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Reason for Request
This amendment request will support preventive maintenance to replace the RHR Train A pump and motor.
Previous experience from replacing just the RHR Train B pump resulted in approximately 6 days out of the 7 day completion time (CT). It is expected that the work needed to replace the RHR Train A pump and motor may not be able to be completed in the current 7 day CT and would necessitate a plant shutdown.
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Precedent A one-time 7 day extension to Columbia TS actions 3.5.1.A, 3.6.1.5.A, and 3.6.2.3.A completion times (ML15031A002) was approved for use at Columbia under license amendment number 230 (ML15030A501) in February 2015.
When the station is on-line, more emergency core cooling system (ECCS) systems and/or subsystems are available to mitigate a design basis accident such as high pressure core spray (HPCS),
low pressure core spray (LPCS), low pressure coolant injection mode (LPCI) of RHR and the automatic depressurization system (ADS).
A mode transition from operating to shutdown brings inherent risk Only one RHR train would be available for shutdown cooling Risk exposure is reduced by staying online 6
Residual Heat Removal (RHR) system The RHR system is comprised of three independent loops. Each loop contains its own motor-driven pump, piping, valves, instrumentation, and controls. In addition, Loops A and B have heat exchangers which are cooled by standby service water (SW).
The RHR system has the following Modes of Operation Low-pressure coolant injection (LPCI) mode Suppression pool cooling (SPC) mode Containment spray cooling (CSC) mode Shutdown cooling mode 7
RHR Shutdown Cooling Mode of Operation 11
LAR Approach This LAR is a risk-informed submittal compatible with current Standard Review Plan (SRP) 5.4.7, 6.2.1.1.C, 6.3, and 16.1 SRP review areas and acceptance criteria will be addressed Regulatory Guide (RG) 1.177 and RG 1.174 will be used to develop the LAR 12
SRP Considerations SRP 5.4.7 There are no changes in the design of the RHR system associated with this LAR SRP 6.2.1.1.C There are no changes in the design of the Containment associated with this LAR SRP 6.3 There are no changes to the ECCS systems associated with this LAR SRP 16.1 The proposed change used the risk-informed approach of RG 1.177 and RG 1.174 13
Technical Evaluation Defense in Depth for Heat Removal Redundant RHR Train B Venting Comp Measures to Protect RHR Trains B and C and support systems Diverse ECCS systems HPCS and LPCS and support systems Reactor Core Isolation Cooling Startup Transformer Division 2 & 3 Diesels and Service Water Systems 14
Technical Evaluation Preliminary Risk Results 14-DAY ALLOWED OUTAGE TIME (AOT) PREVENTIVE MAINTENANCE Average Maintenance Model without Protected Trains Risk Acceptance Risk Assessment Metric Guideline Results ICCDP < 1.0E-6 8.32E-7 ICLERP < 1.0E-7 1.23E-9 14-DAY AOT PREVENTIVE MAINTENANCE Average Maintenance Model with Protected Trains & Compensatory Measures Risk Acceptance Risk Assessment Metric Guideline Results ICCDP < 1.0E-6 3.95E-7 ICLERP < 1.0E-7 6.90E-10 15
Technical Evaluation Columbia PRA Technical Adequacy Columbia Internal Events (with internal flooding) PRA satisfies RG 1.200 NRC SAMA Review Documented in ML12096A334 PSA currently under additional review for Energy Northwests LAR to adopt TSTF-425 ML15093A178
- Responses to Requests for Additional Information (RAIs) related to Columbias PSA model ML15260A570, ML15302A492, ML160984A387 and ML16174A432 Fire and seismic PRA do not meet RG 1.200 PRAs have been updated to use the current internal events PRA Insights into dominant risk contributors are applicable 16
Conclusion The proposed one time 7 day extension of completion time for TS 3.5.1.A, 3.6.1.5.A, and 3.6.2.3.A meets the five key RG 1.177 principles for risk-informed TS changes as follows:
meets the current regulations, is consistent with the defense-in-depth philosophy, maintains sufficient safety margins, quantitative results for ICCDP and ICLERP application are less than the guidance thresholds and are consistent with the intent of the Commissions Safety Goal Policy Statement, and impact will be monitored using performance measurement strategies associated with the Mitigating Systems Performance Index and Columbias Maintenance Rule a(4) program.
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