ML101670319
| ML101670319 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 06/16/2010 |
| From: | Cowan P Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML101670319 (14) | |
Text
ExeIn N c]ear 10 CFR 50.90 June 16, 2010 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Units 1 and 2 Facility Operating License Nos, NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-35
Subject:
License Amendment Request Supplemental Information Proposed Changes to Technical Specifications Sections 3.5.1, 3.6.2.3, 3.7.1.1, 3.7.1.2 and 3.8.1.1 to Extend the Allowed Outage Times
Reference:
Letter from P. 8. Cowan (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, License Amendment Request, Proposed Changes to Technical Specifications Sections 3.5.1, 3.6.2.3, 3.7.1.1, 3.7.1.2 and 3.8.1.1 to Extend the Allowed Outage Times, dated March 19, 2010.
In the referenced letter, Exelon Generation Company, LLC (Exelon) requested changes to the Technical Specifications (TS), Appendix A of Operating License Nos. NPF-39 and NPF-85 for Limerick Generating Station (LGS), Units 1 and 2, respectively. The proposed changes would extend the TS allowed outage time (AOT) for the Unit 1 and Unit 2 Suppression Pool Cooling (SPC) mode of the Residual Heat Removal (RHR) system, the Residual Heat Removal Service Water (RHRSW) system, the Emergency Service Water (ESW) system, and the A.C. Sources Operating (Emergency Diesel Generators) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to seven (7) days in order to allow for repairs of the RHRSW system piping. Attachment 3 of the referenced letter provided an evaluation of the technical adequacy of the Probabilistic Risk Assessment (PRA) and summary of PRA assessment in accordance with Regulatory Guide 1.200, Revision 1.
During a conference call with the NRC on May 11, 2010, the NRC indicated that, with respect to Tables 4-2 and 4-3 in Attachment 3 of the referenced letter, a more detailed discussion of the identified gaps was needed, rather than the associated supporting requirement descriptions. As a result, the attachment to this letter provides revised versions of Tables 4-2 and 4-3 that include a discussion of the gaps identified during the PRA peer review. As discussed during the conference call with the NRC, the items that were previously identified in Tables 4-2 and 4-3 in of the referenced letter as being addressed in the last PRA model update with no impact on the application are not included in the revised tables.
Exelon Nuclear 20 0 Exelon Way Kennett Square. PA 19348 June 16, 2010 www exelon corp.com Exelon.
Nuclear 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Units 1 and 2 Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353
Subject:
License Amendment Request Supplemental Information Proposed Changes to Technical Specifications Sections 3.5.1,3.6.2.3,3.7.1.1,
3.7.1.2 and 3.8.1.1 to Extend the Allowed Outage Times
Reference:
Letter from P. B. Cowan (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "License Amendment Request, Proposed Changes to Technical Specifications Sections 3.5.1, 3.6.2.3, 3.7.1.1, 3.7.1.2 and 3.8.1.1 to Extend the Allowed Outage Times," dated March 19, 2010.
In the referenced letter, Exelon Generation Company, LLC (Exelon) requested changes to the Technical Specifications (TS), Appendix A of Operating License Nos. NPF-39 and NPF-85 for Limerick Generating Station (LGS), Units 1 and 2, respectively. The proposed changes would extend the TS allowed outage time (AOT) for the Unit 1 and Unit 2 Suppression Pool Cooling (SPC) mode of the Residual Heat Removal (RHR) system, the Residual Heat Removal Service Water (RHRSW) system, the Emergency Service Water (ESW) system, and the A.C. Sources -
Operating (Emergency Diesel Generators) from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to seven (7) days in order to allow for repairs of the RHRSW system piping. Attachment 3 of the referenced letter provided an evaluation of the technical adequacy of the Probabilistic Risk Assessment (PRA) and summary of PRA assessment in accordance with Regulatory Guide 1.200, Revision 1.
During a conference call with the NRC on May 11, 2010, the NRC indicated that, with respect to Tables 4-2 and 4-3 in Attachment 3 of the referenced letter, a more detailed discussion of the identified gaps was needed, rather than the associated supporting requirement descriptions. As a result, the attachment to this letter provides revised versions of Tables 4-2 and 4-3 that include a discussion of the gaps identified during the PRA peer review. As discussed during the conference call with the NRC, the items that were previously identified in Tables 4-2 and 4-3 in of the referenced letter as being addressed in the last PRA model update with no impact on the application are not included in the revised tables.
License Amendment Request Supplemental Information Docket Nos. 50-352 and 50-353 June 16, 2010 Page 2 Exelon has reviewed the information supporting a finding of no significant hazards consideration, and the environmental consideration, that were previously provided to the NRC in of the referenced letter, Exelon has concluded that the additional information provided in this submittal does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration.
In addition, Exelon has concluded that the additional information in this submittal does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.
There are no regulatory commitments contained in this letter.
If you have any questions or require additional information, please contact Glenn Stewart at 610-765-5529.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 16th day of June 2010.
Respectfully,
ói4t4 Pamela B.
owan Director, Licensing & Regulatory Affairs Exelon Generation Company, LLC
Attachment:
Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy cc:
Regional Administrator
- NRC Region I
w/ attachment NRC Senior Resident Inspector
- Limerick Generating Station NRC Project Manager, NRR
- Limerick Generating Station Director, Bureau of Radiation Protection
- Pennsylvania Department of Environmental Protection License Amendment Request Supplemental Information Docket Nos. 50-352 and 50-353 June 16, 2010 Page 2 Exelon has reviewed the information supporting a finding of no significant hazards consideration, and the environmental consideration, that were previously provided to the NRC in of the referenced letter. Exelon has concluded that the additional information provided in this submittal does not affect the bases for concluding that the proposed license amendment does not involve a significant hazards consideration. In addition, Exelon has concluded that the additional information in this submittal does not affect the bases for concluding that neither an environmental impact statement nor an environmental assessment needs to be prepared in connection with the proposed amendment.
There are no regulatory commitments contained in this letter.
If you have any questions or require additional information, please contact Glenn Stewart at 610-765-5529.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on the 16th day of June 2010.
Respectfully, p~~
Director, Licensing & Regulatory Affairs Exelon Generation Company, LLC
Attachment:
Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy cc:
Regional Administrator - NRC Region I NRC Senior Resident Inspector - Limerick Generating Station NRC Project Manager, NRR - Limerick Generating Station Director, Bureau of Radiation Protection - Pennsylvania Department of Environmental Protection wI attachment
ATTACHMENT License Amendment Request Supplemental Information Limerick Generating Station, Units 1 and 2 Docket Nos. 50-352 and 50-353 Proposed Changes to Technical Specifications Sections 3.5.1, 3.6.2.3, 3.7.1.1, 3.7.1.2 and 3.8.1.1 Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy
License Amendment Request Supplemental Information Page 1 of 11 Docket Nos. 50-352 and 50-353 ATTACHMENT Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy TABLE 4-2 IMPACT OF PRA STANDARD SUPPORTING REQUIREMENTS NOT AT LEAST CATEGORY II FOR THE LIMERICK PRA MODEL SR(S)
ISSUE DESCRIPTION IMPACT ON BASE MODEL IMPACT ON APPLICATION IE-A7 Review plant-specific operating experience for initiating event pre-cursors.
This supporting requirement (SR) was assigned as meeting only Category I since formal documentation of the pre-cursor review was not provided.
Minimal impact. The Limerick initiating event development is thorough and includes a comprehensive set of initiating events consistent with most industry BWRs.
Although a formal pre-cursor review was not performed, the current treatment is believed to provide the best estimate response for the plant, and as such not fully meeting this SR has minimal impact on the base model analysis and for most applications of the model.
Minimal impact. A full range of initiating events are included in the model.
SY-A12b Include those failures that can cause flow diversion pathways that result in failure to meet the system success criteria.
This SR was identified as Not Met since it was identified that the HPCI min-flow valve failure to close should be modeled.
Very minimal impact. The failure of the min-flow valve to close was incorporated into the HPCI system logic model as part of the 2008 update. Diversion paths were considered in the development of all of the system logic models. All relevant single valve failures are included. A detailed investigation to look for additional potential diversion paths stemming from multiple valve failures would have a small impact on the CDF and LERF results, and as such will not significantly impact the base model assessment.
Minimal impact. Flow diversion failures will not significantly add to the existing system or train failure probabilities.
Additionally, there are compensatory measures identified that will ensure proper alignment of the ESW/RHRSW return path and standby RHR loop prior to entering the extended AOT configuration. This will reduce the risk associated with potential flow diversions.
License Amendment Request Supplemental Information Page 2 of 11 Docket Nos. 50-352 and 50-353 ATTACHMENT Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy TABLE 4-2 IMPACT OF PRA STANDARD SUPPORTING REQUIREMENTS NOT AT LEAST CATEGORY II FOR THE LIMERICK PRA MODEL SR(S)
ISSUE DESCRIPTION IMPACT ON BASE MODEL IMPACT ON APPLICATION HR-A1 The SR indicates that the test and maintenance pre-initiators should be derived from a review of procedures and practices.
This SR was identified as met during the peer review, but was later identified as a potential gap for Limerick based on findings from other Exelon peer reviews.
Very minimal impact. The model includes several test and maintenance pre-initiators for a number of risk significant systems, but these were not derived from a formal review of procedures and practices.
No impact. Test and maintenance pre-initiators exist for all relevant systems associated with this LAR (i.e., HPCI, RCIC, EDG, and RHRSW loops).
Additionally, compensatory measures are identified that ensure availability of important equipment prior to entering the extended AOT configuration.
DA-C6 The SR is to determine the standby component number of demands based on plant specific:
surveillance tests maintenance acts surveillance tests or maintenance on other components operational demands.
The peer review finding indicated that the methods used to determine exposures (demands, runtime, etc.) were not documented. The reviewer could not validate how demands were obtained.
Minimal impact. For the most part, the estimated demands were determined from the Maintenance Rule database. This database specifically includes the contribution from the listed items, but the contribution is not specifically mapped to each in all cases.
The current treatment provides a reasonable representation of the best estimate response for the plant, and as such not fully meeting this SR has minimal impact on the base model analysis and for most applications of the model.
Minimal impact. The current data values provide a reasonable representation of the best estimate reliability response for the plant based on plant specific data.
License Amendment Request Supplemental Information Page 3 of 11 Docket Nos. 50-352 and 50-353 ATTACHMENT Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy TABLE 4-2 IMPACT OF PRA STANDARD SUPPORTING REQUIREMENTS NOT AT LEAST CATEGORY II FOR THE LIMERICK PRA MODEL SR(S)
ISSUE DESCRIPTION IMPACT ON BASE MODEL IMPACT ON APPLICATION DA-C7 The SR states to base the number of tests, maintenance activities, and unplanned maintenance on actual plant experience.
The peer review finding indicated that the methods used to determine exposures (demands, runtime, etc.) were not documented. The reviewer could not validate how demands were obtained.
Minimal impact. The estimated demands were mostly determined from the Maintenance Rule database which is compiled from actual performance data.
Thus, providing documentation of the maintenance and test procedures and how they are used to estimate demands is unnecessary.
The current treatment provides a reasonable representation of the best estimate response for the plant, and as such not fully meeting this SR has minimal impact on the base model analysis and for most applications of the model.
Minimal impact. The current data values provide a reasonable representation of the best estimate reliability response for the plant based on actual plant data.
IF-B3 The SR specifies that the total volume and temperature and pressure of the flood source be specified.
The peer review finding indicated that since flood areas are documented as screened based on limited system volume, additional scenarios may need to be considered in the PRA if the system volume is considered.
Very minimal impact. This is only a documentation issue as screening of scenarios was not based on volume of water within the system. It was based on initiating event frequencies and bounding CCDPs with no credit for mitigation measures.
Minimal impact. Flooding scenarios are not significant contributors for the proposed RHRSW/SPC AOT extension (Refer to, Appendix B, Table B-2 of the original submittal). Fully addressing this SR is not expected to have a significant impact on the internal flood contribution to this application.
License Amendment Request Supplemental Information Page 4 of 11 Docket Nos. 50-352 and 50-353 ATTACHMENT Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy TABLE 4-2 IMPACT OF PRA STANDARD SUPPORTING REQUIREMENTS NOT AT LEAST CATEGORY II FOR THE LIMERICK PRA MODEL SR(S)
ISSUE DESCRIPTION IMPACT ON BASE MODEL IMPACT ON APPLICATION IF-C2b The SR calls for an accounting for drains in estimating flood volumes and SSC impacts from flooding.
The peer review finding indicated that no specific analysis of drains appears to have been performed and that calculation of the drain capacities was not evident.
Very minimal impact. The few scenarios that were analyzed in detail typically did not credit drain capacities in determining time available to respond.
However, two scenarios did credit drainage. One of those areas was an upper area of the reactor enclosure where drainage to lower elevations would be virtually ensured by the presence of an open hatch in addition to the drains. The other scenario was for the reactor safeguards and isolation valve area where drainage failure was assumed to be required for component damage to occur. This is a reasonable assumption given the overall drain capacities and ability to transfer water as necessary to mitigate large flooding events such that the base model results provide representative results for the potential impact from internal flooding events.
Minimal impact. Flooding scenarios are not significant contributors for the proposed RHRSW/SPC AOT extension (Refer to, Appendix B, Table B-2 of the original submittal). Fully addressing this SR is not expected to have a significant impact on the internal flood contribution to this application.
Additionally, sensitivity calculations indicate that there would be less than a 1% impact on the calculated delta-CDFs if no credit were taken for the drains in the reactor safeguard and isolation valve area.
License Amendment Request Supplemental Information Page 5 of 11 Docket Nos. 50-352 and 50-353 ATTACHMENT Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy TABLE 4-2 IMPACT OF PRA STANDARD SUPPORTING REQUIREMENTS NOT AT LEAST CATEGORY II FOR THE LIMERICK PRA MODEL SR(S)
ISSUE DESCRIPTION IMPACT ON BASE MODEL IMPACT ON APPLICATION IF-C3(1)
This SR was only assigned a Category I since the RG 1.200 clarification for meeting Category II requires a qualitative assessment of the flooding mechanisms that are not formally addressed (e.g.,
using the mechanisms listed under Capability Category III of this requirement), by using conservative assumptions.
The peer review finding indicated that the basis provided, which referred to the dynamic effects of pipe breaks being considered in the design process, was not sufficient as the specific equipment evaluated in the PRA compared to the equipment considered in the design analysis, e.g., EQ lists, was not documented.
Minimal impact. Although the explicit consideration of these failure mechanisms might ultimately introduce a few additional scenarios, the approach which initially utilizes bounding assumptions regarding the failure of all equipment in the flood area for the initial CCDP determination would tend to overshadow the potential risk increase associated with these low likelihood events.
Minimal impact. Flooding scenarios are not significant contributors for the proposed RHRSW/SPC AOT extension (Refer to, Appendix B, Table B-2 of the original submittal). Fully addressing this SR is not expected to have a significant impact on the internal flood contribution to this application.
License Amendment Request Supplemental Information Page 6 of 11 Docket Nos. 50-352 and 50-353 ATTACHMENT Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy TABLE 4-2 IMPACT OF PRA STANDARD SUPPORTING REQUIREMENTS NOT AT LEAST CATEGORY II FOR THE LIMERICK PRA MODEL SR(S)
ISSUE DESCRIPTION IMPACT ON BASE MODEL IMPACT ON APPLICATION IF-C3b(1)
This SR was only assigned a Category I since the RG 1.200 clarification for meeting Category II requires that potential barrier unavailability be included in the inter-area propagation identification process.
The peer review finding indicated that no consideration of barrier unavailability due to maintenance, and how such unavailability could affect flood scenarios, was documented.
An additional finding supporting Category I was identified based on the identification of drains and electrical penetrations in the EDG rooms not being addressed for potential back flow considerations. Also, potential backflow considerations from drains in the control enclosure, turbine enclosure, and reactor enclosure are not addressed.
Minimal impact. Flood barrier unavailability is controlled at the site, and would at most lead to short time frames where additional potential flood scenarios would exist. The short time frames involved ensure that these would be small or negligible risk contributors.
Although the consideration of back flow through drains and electrical penetrations might lead to the identification of a few new flood scenarios, the added time associated with flood propagation through these mechanisms before additional equipment is failed would lead to small or negligible risk contributors.
Minimal impact. Flooding scenarios are not significant contributors for the proposed RHRSW/SPC AOT extension (Refer to, Appendix B, Table B-2 of the original submittal). Fully addressing this SR is not expected to have a significant impact on the internal flood contribution to this application.
License Amendment Request Supplemental Information Page 7 of 11 Docket Nos. 50-352 and 50-353 ATTACHMENT Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy TABLE 4-2 IMPACT OF PRA STANDARD SUPPORTING REQUIREMENTS NOT AT LEAST CATEGORY II FOR THE LIMERICK PRA MODEL SR(S)
ISSUE DESCRIPTION IMPACT ON BASE MODEL IMPACT ON APPLICATION IF-D5a(1)
This SR was only assigned a Category I since plant-specific experience was not directly factored into the development of the internal flood initiating event frequencies.
The peer review observation was to update the frequencies using a Bayesian update.
However, this was only identified as a suggestion (not a finding) since it was recognized that this would not appreciably change the overall pipe failure frequencies.
Minimal impact. As noted by the peer reviewer, it is not expected that a revised assessment would appreciably change the overall pipe failure frequencies.
Minimal impact. Flooding scenarios are not significant contributors for the proposed RHRSW/SPC AOT extension (Refer to, Appendix B, Table B-2 of the original submittal). Fully addressing this SR is not expected to have a significant impact on the internal flood contribution to this application.
IF-E5a The SR calls for a systematic assessment of the existing operator actions that are included in flood sequences.
The peer review finding indicated that no systematic assessment of the existing operator actions that are included in the flood sequences was performed.
Minimal impact. Supporting detailed HEP evaluations were developed for the major flood contributors.
Further analysis for all existing HEPs associated with the flooding analysis is not expected to significantly impact the results where all but a few contributors were left in the model as bounding scenarios.
Minimal impact. Flooding scenarios are not very significant contributors for the proposed RHRSW/SPC AOT extension (Refer to, Appendix B, Table B-2 of the original submittal). Fully addressing this SR is not expected to have a significant impact on the internal flood contribution to this application.
(1) Note that the discussion for this SR, which was identified as meeting Category I in the internal flood PRA peer review report, was inadvertently omitted from Table 4-2 in the original LAR submittal, and is provided here with this supplemental information for completeness.
License Amendment Request Supplemental Information Page 8 of 11 Docket Nos. 50-352 and 50-353 ATTACHMENT Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy TABLE 4-3 IMPACT OF SIGNIFICANT PRA PEER REVIEW FINDINGS FOR THE LIMERICK PRA MODEL SR(S)
ISSUE DESCRIPTION IMPACT ON BASE MODEL IMPACT ON APPLICATION AS-B3 For each accident sequence, identify the phenomenological conditions created by the accident progression.
The peer review finding indicated that the discussion contained in the event tree notebook indicates that there are no additional impacts associated with the breaks of RWCU, main steam, HPCI and others when the break occurs outside the containment, but that the basis for that assumption has not been adequately documented.
Very minimal impact.
Although other failures may occur due to the environmental conditions resulting from a pipe break outside of containment, the current treatment that ultimately relies on injection from an external source outside of the reactor enclosure dominates the impact of these events, and as such not fully addressing this finding has minimal impact on the base model analysis and most applications of the model.
Minimal impact. High energy line break scenarios are not very significant contributors for the proposed RHRSW/SPC AOT extension (Refer to, Appendix B, Table B-2 of the original submittal).
HR-H3 Account for any dependency between the HFE for operator recovery and any other HFEs.
The peer review finding indicated that common cause operator error events are included across system boundaries, but it appears that some cross system combinations are not addressed, but rather are dismissed as risk negligible. It was suggested that an alternative method could be employed to handle human error dependencies across system boundaries.
Very minimal impact. The approach used in the Limerick model does account for dependencies across system boundaries in an appropriate fashion and utilizes a standard approach to do so. All of the HFE dependency examples provided in the finding are already included in the Limerick model, and restructuring the current analysis to the suggested approach will have a minimal impact on the overall CDF and LERF results, and as such would not significantly impact the results of the base model assessment or applications.
Minimal impact. Human error dependencies are addressed in the PRA model used for this application.
This finding is better characterized as a suggestion of a potential alternate means of addressing human error dependencies.
License Amendment Request Supplemental Information Page 9 of 11 Docket Nos. 50-352 and 50-353 ATTACHMENT Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy TABLE 4-3 IMPACT OF SIGNIFICANT PRA PEER REVIEW FINDINGS FOR THE LIMERICK PRA MODEL SR(S)
ISSUE DESCRIPTION IMPACT ON BASE MODEL IMPACT ON APPLICATION DA-B1 Group components according to their type and according to the characteristics of their usage.
A peer review finding indicated that Category II requires usage characteristics to be included in the component grouping. The use of Maintenance Rule data may take this into account for some components; however, there is no discussion to support the extent to which this requirement is met.
Very minimal impact. The updated data analysis utilizes groupings consistent with the available data including the recently implemented generic data from NUREG/CR-6928. Full compliance with this finding is simply a documentation issue, and as such would not significantly impact the results of the base model assessment or in applications.
Minimal impact. The current data values provide a reasonable representation of the best estimate reliability response for the plant similar to the impact on the base PRA model.
DA-B2 Do not include outliers in the definition of a group.
A peer review finding indicated that there is no discussion of unique components or how outliers (if any) were treated.
No specific examples were found that created an issue; however, there is no assurance that they were evaluated.
Very minimal impact. A formal analysis to find outliers was not performed, but this is mostly expected to be a documentation issue, and in any event will not have a substantial impact on the CDF and LERF results.
As such, fully addressing this finding would not significantly impact the results of the base model assessment or in applications.
Minimal impact. The current data values provide a reasonable representation of the best estimate reliability response for the plant.
License Amendment Request Supplemental Information Page 10 of 11 Docket Nos. 50-352 and 50-353 ATTACHMENT Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy TABLE 4-3 IMPACT OF SIGNIFICANT PRA PEER REVIEW FINDINGS FOR THE LIMERICK PRA MODEL SR(S)
ISSUE DESCRIPTION IMPACT ON BASE MODEL IMPACT ON APPLICATION DA-C10 Count only completed tests or unplanned operational demands as success for component operation.
A peer review finding indicated that there is no documentation to support this requirement. If surveillance test data was not used then this SR is n/a.
Otherwise, additional documentation is needed to determine how surveillance test data was used as a basis to count component demands to validate that the SR is met.
No impact. This was performed for some systems, but not all.
However, it is also not necessary since the failure and demand data includes actual plant experiential data over the last several years for the Maintenance Rule risk significant systems.
No Impact.
DA-C12 Evaluate the duration of the actual time that the equipment was unavailable for each contributing activity and interview maintenance and operations staff to generate estimates of ranges in the unavailable time.
A peer review finding indicated that interviews with maintenance and operations was not documented to support this SR.
No impact. The total unavailability data includes actual plant test and maintenance experiential data over the last several years for the Maintenance Rule risk significant systems.
No Impact.
License Amendment Request Supplemental Information Page 11 of 11 Docket Nos. 50-352 and 50-353 ATTACHMENT Additional Information Supporting Probabilistic Risk Assessment Technical Adequacy TABLE 4-3 IMPACT OF SIGNIFICANT PRA PEER REVIEW FINDINGS FOR THE LIMERICK PRA MODEL SR(S)
ISSUE DESCRIPTION IMPACT ON BASE MODEL IMPACT ON APPLICATION IF-C2a For each flood zone and flood source, include in the documentation the specific automatic or operator actions that could be taken to isolate each flood event.
This SR was identified as met by the peer review team, but a finding was issued since the specific actions, such as close valve xxx, are not described in detail.
No impact. No automatic actions were identified as being credited for flood termination or mitigation.
Operator actions that are credited with terminating or mitigating a flooding event are generally described but could benefit from more detailed reference to specific valve numbers, etc.
No Impact.