LR-N10-0309, Supplement to RAI Responses Submitted in PSEG Letter LR-N10-0164 Dated May 24, 2010, Related to the Severe Accident Mitigation Alternatives (SAMA)

Supplement to RAI Responses Submitted in PSEG Letter LR-N10-0164 Dated May 24, 2010, Related to the Severe Accident Mitigation Alternatives (SAMA)

ML102320211
Person / Time
Site:	Salem
Issue date:	08/18/2010
From:	Neely C Public Service Enterprise Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LR-N10-0309, FOIA/PA-2011-0113
Download: ML102320211 (26)

Text

PSEG Nuclear LLC P.O. Box 236, Hancocks Bridge, NJ 08038 0 PSEG NuclearLLC AUG 18 2010 10 CFR 50 10 CFR 51 10 CFR 54 LR-N10-0309 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Salem Nuclear Generating Station, Unit No. 1 and Unit No. 2 Facility Operating License Nos. DPR-70 and DPR-75 NRC Docket Nos. 50-272 and 50-311

Subject:

Supplement to RAI responses submitted in PSEG letter LR-N10-0164 dated May 24, 2010, related to the Severe Accident Mitigation Alternatives (SAMA) review of the Salem Nuclear Generating Station, Units 1 and 2.

References:

1. Letter from Mr. Charles Eccleston (USNRC) to Mr. Thomas Joyce (PSEG Nuclear, LLC) "Request For Additional Information Regarding Severe Accident Mitigation Alternatives For Salem Nuclear Generating Station, Units 1 And 2",

dated April 12, 2010

2. Letter from Mr. Paul J. Davison (PSEG Nuclear, LLC) "Response to NRC Request for Additional Information", dated April 12, 2010, related to the Severe Accident Mitigation Alternatives (SAMA) review of the Salem Nuclear Generating Station, Units 1 and 2.

3. Teleconference held on July 29, 2010 between the USNRC Staff and PSEG Nuclear regarding clarifications to the RAI responses provided in the Reference 2 letter.

In the Reference 1 letter, the NRC requested additional information related to the Severe Accident Mitigation Alternatives (SAMA) review of the Salem Nuclear Generating Station, Units 1 and 2. In the Reference 2 letter, PSEG responded to the NRC's requests for additional information related to SAMA. In the Reference 3 teleconference the NRC Staff sought clarification pertaining to some of the PSEG SAMA RAI responses. The enclosed supplement provides that clarification.

This letter and its enclosure contain no regulatory commitments. A o,,c

AUG 18 2010 Document Control Desk LR-N 10-0309 Page 2 If there are questions, please contact Helen Gregory, Environmental Manager, PSEG Nuclear, at 856-339-1341 I declare under penalty of perjury that the foregoing is true and correct.

Executed on 10 Sincerely, Chris e T. Neel Director, Regulatory Affairs PSEG Nuclear LLC

Enclosure:

Supplement to SAMA RAI Responses cc: Regional Administrator - USNRC Region I C. Eccleston, Environmental Project Manager, License Renewal - USNRC R. Ennis, Project Manager - USNRC NRC Senior Resident Inspector - Salem P. Mulligan, Manager IV, NJBNE L. Marabella, Corporate Commitment Tracking Coordinator Howard Berrick, Salem Commitment Tracking Coordinator

LR-N1 0-0309 Enclosure Enclosure Supplement to RAI responses submitted in PSEG letter LR-N10-0164 dated May 24, 2010, related to the Severe Accident Mitigation Alternatives (SAMA) review of the Salem Nuclear Generating Station (SGS), Units 1 and 2 NOTE: A list of acronyms and abbreviations used in this response is provided at the end of this document.

Page 1 of 24

LR-N1 0-0309 Enclosure

1. Clarification requested regarding RAI 1.c.

PSEG provided a description and SAMA impact analysis of 8 "key" findings from the November 2008 PWR Owner's Group, and stated that the scope of the peer review included Level 1, Level 2, and internal flooding. The summary provided does not sufficiently describe the results of the peer review and, furthermore, none of the "key" findings are related to the new Level 2 model. Provide a table of each supporting requirement that is either Capability Category 1 or Not Met. For each of these supporting requirements, provide an assessment of the impact on the SAMA analysis of not meeting Capability Category 2 or 3, or alternatively, justify that the capability category assignment is adequate for the SAMA application. In addition, provide an overall assessment of the impact on the SAMA analysis of all Supporting Requirements determined by the peer review team to not meet Capability Category 2 or 3.

Response

A formal peer review of the Rev. 4.1 Probabilistic Risk Assessment (PRA) Model was performed in November 2008 against Addendum B of the PRA Standard [ASME 2005]

and the criteria in Regulatory Guide (RG) 1.200, Rev. 1 [NRC 2007a], including the NRC positions stated in Appendix A of RG 1.200, Rev. 1, and further issue clarifications [NRC 2007b]. The supporting requirements (SRs) identified from the peer review as not meeting Capability Category 2 or 3 that remain open in the Rev. 4.3 PRA Model are summarized in Table 1-1 below along with an assessment of the impact on the base PRA model and Severe Accident Mitigation Alternatives (SAMA) analysis. The below table also lists those SRs associated with the Level 2 model that were identified as not meeting Capability Category 2 or higher.

Although the SAMA analysis is not considered a risk-informed application that requires a discussion on technical adequacy and compliance with RG 1.200, all identified SRs that the peer review team identified as not meeting Capability Category 2 or higher will be reviewed for consideration during the next periodic PRA model update. Overall, these identified SRs have only a minimal impact on the SAMA analysis and would be well within the range of the 9 5 th percentile uncertainty analysis provided in Section E.7.2 of the SGS License Renewal Environmental Report.

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LR-N 10-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard Title Resolution Applicable Impact on Base PRA Model or SAMA Supporting Analysis Requirements IE-Al-01 A loss of an AC bus may not result in a reactor trip, but may result in a IE-Al Minimal impact on SAMA analysis; forced shutdown due to technical specifications. If the lost bus referenced event is bounded by the happens to be the operating bus for equipment, systems will be modeled reactor trip initiator.

challenged. Loss of an AC bus is generally modeled in most PRAs.

This fact and observation (F&O) is characterized as a finding based on the lack of sufficient documentation to allow verification of SR.

Include events for loss of 4Kv bus if they require a forced shutdown consistent with most industry PRAs.

IE-A3-01 Historical events appear to lead to somewhat more complex situations IE-A3 Negligible impact on technical adequacy of than the assigned grouping would indicate. The plant-specific history the PRA model. Referenced event was indicates that on 12/31/01 an event occurred resulting in SI. The binned as a trip with loss of Feed water, categorization of initiating events does not account for this or the case consistent with the classification scheme of ESFAS actuation. employed for the Salem PRA. No impact on This F&O is characterized as a finding based on the lack of sufficient the SAMA analysis.

documentation to allow verification of SR.

Consider re-categorizing this event as an ESFAS actuation (QR9).

IE-A3a-01 Although sited as an input source, there appears to be no IE-A3a This is a documentation consideration only documentation supporting a comparison of initiating events with regard and does not affect the technical adequacy to plants of similar design. The documentation indicates that "past of the PRA model. No impact on the SAMA probabilistic risk assessments" were used for source and experience, analysis.

However, there is not documentation of such a comparison. It also does not identify that any examination was made for Salem-like designs. A comparison to similar designs can potentially identify those design-specific events than may have unique consequences which may not be defined in more generic sources. It also provides an industry basis for selection.

This F&O is characterized as a finding based on the lack of sufficient documentation to allow verification of SR.

Utilize available industry summary documentation to define generally appropriate initiating event list for specific design.

IE-A4-01 The requirement is to address each system, including support systems IE-A4 This is a documentation consideration only to assess potential for initiating events. The analysis only addresses and does not affect the technical adequacy support systems and does not address the impact of other operating of the PRA model. No impact on the SAMA systems with regard to events resulting in a plant upset and analysis.

subsequent trip signal. For charging this has the potential to impact both the initiator and response models such that consequential failures could be possible.

Page 3 of 24

LR-1N 10-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard This F&O is characterizing as a finding based on the lack of sufficient documentation to allow verification of SR.

Add evaluations for frontline operating systems that in particular are part of the PRA response model.

IE-A5-01 SA PRA Initiating Events Notebook, SA-PRA-001, Revision 0, Section IE-A5 This is a documentation consideration only 2.1.2 describes the review of Salem Generating Station Experience and and does not affect the technical adequacy Trip Review. No mention is made of consideration of events that of the PRA model. No impact on the SAMA occurred at conditions other than at-power operation. Also, events analysis.

resulting in controlled shutdown were excluded on the basis that they present only mild challenges rather than being determined to be not applicable to at-power operation.

Failure to consider non-power events and controlled shutdown events could result in exclusion of valid initiating events.

Provide an explicit discussion of the review of non-power events.

Improve the justification for exclusion of controlled shutdown events to address applicability to at-power operation or to provide a quantitative justification for exclusion.

IE-A6-01 SA PRA Initiating Events Notebook, SA-PRA-001, Revision 0, Section IE-A6 This is a documentation consideration only 2.1.2 does not indicate that plant operations, maintenance, and does not affect the technical adequacy engineering, and safety analysis personnel were interviewed or of the PRA model. No impact on the SAMA included in the review process for the initiating events notebook to analysis.

determine if potential initiating events have been overlooked.

Documentation was not available to show that the Category 2/33 requirement was satisfied. The initiating event analysis should document a reasonably complete identification of initiating events.

Document the required interviews.

IE-A7-01 SA PRA Initiating Events Notebook, SA-PRA-001, Revision 0, Section IE-A7 This is a documentation consideration only 2.1.2 does not indicate that a review of plant-specific or industry and does not affect the technical adequacy operating experience was performed for the purpose of identifying of the PRA model. No impact on the SAMA initiating event precursors. analysis.

Failure to consider precursor events and controlled shutdown events could result in exclusion of valid initiating events.

The model owner stated that precursors were considered during the review of plant operating experience. However, because this is not documented, the SR cannot be considered met. This should be explicitly stated in the Initiating Events Notebook.

IE-B3-01 Initiating events are not grouped with less severe events without IE-B3, AS-A5 Minimal impact on the ability to assess assuming the worst potential effects. For example, the potential for a averted cost-risks associated with the SAMA spurious SI actuation is grouped in the general transient category with analysis. Issue only relates to development events such as reactor trip and considered to be no worse than the of initiating events for inclusion in the PRA reactor trip. However, unmitigated spurious SI events can challenge a model.

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LR-N10-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard PORV resulting in a consequential LOCA. Spurious SI events should not be grouped with general reactor trips. Also, the loss of AC power bus (F) is said to result in a degraded loss of condensate/feedwater performance. However, it is placed in the PCS available category.

This presents a problem when developing the conditional failure PCS in

,response to the event.

This F&O is characterized as a finding based on the lack of sufficient documentation to allow verification of SR.

Separate out events on basis of unique impacts to the response sequence.

IE-Clb-01 The loss of SW initiating event fault tree S1 R4.Caf (gate IE-TSW) was IE-Clb, IE-C6 This is a documentation consideration only reviewed and the logic appears to capture the appropriate and does not affect the technical adequacy combinations of equipment failures that contribute to the initiator. of the PRA model. No impact on the SAMA However, the documentation of the development of the initiator fault analysis.

trees appears to be lacking. Section 3.3 of the Salem SA-PRA-001, Revision 0 notebook does not provide much detail of how the initiators modeled as fault trees are developed. It refers to the system model notebook. For the loss of SW initiator, the SW model notebook SA-PRA-005.13, Revision 0 was reviewed and there was no discussion of the development of the loss of SW initiator fault tree. For the loss of CC initi ator fault tree, Section 4.2 of notebook SA-PRA-005.12, Revision 0 provides a good description of how that initiator fault tree is developed.

This F&O is characterized as a finding based on the lack of sufficient documentation to allow verification of SR IE-Clb.

Document how the loss of SW initiating event fault tree is developed.

Likewise for other system initiators as needed. Include a discussion of the recoveries credited in the initiator. This should also be done for the other initiators that are fault trees.

IE-C3-01 The initiators that are fault trees, such as loss of SW and loss of CC, IE-C3 This is a conservative modeling issue and the initiator frequency is not based on reactor year. For example, would not adversely impact the SAMA under gate IE-TSW, basic event SWS-PIP-RP-TBHDR has a mission analysis with regard to computing averted time of 8760 hours0.101 days <br />2.433 hours <br />0.0145 weeks <br />0.00333 months <br />. cost-risks.

This F&O is characterized as a finding because it does not meet the SR.

Use reactor year when quantifying the initiator frequencies.

AS-A7-01 Accident Sequences and Event Tree Development Notebook, SA-PRA- AS-A7 This is a documentation consideration only 002, Revision 0 delineates the possible accident sequences for each and does not affect the technical adequacy modeled initiating event. However, some sequences are not explicitly of the PRA model. No impact on the SAMA modeled in the single-top fault tree (e.g., TT sequences S04 and S05 analysis.

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LR-N1 0-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard are combined into a single fault tree gate). No documentation was found to describe the basis of these combinations.

Subsuming non-minimal sequences in the single-top fault tree model could result in loss of risk insights or masking of importance in non-standard configurations.

Provide a description of the process used to combine non-minimal sequences with their bounding equivalent sequence in both the Accident Sequences and Event Tree Notebook or in the Quantification Notebook. Discuss how it is ensured that risk insights are not impacted by the subsuming of sequences. Provide a more complete basis for not modeling sequences judged to have "very low frequencies" such that a reviewer can evaluate the basis for the exclusion.

AS-A7-02 The VS ISLOCA sequence with no piping failure is assumed to be AS-A7 This is a documentation consideration only terminated with operator isolation of the suction path using the pump and does not affect the technical adequacy suction isolation MOVs. However, isolation cannot be accomplished of the PRA model. No impact on the SAMA until primary pressure is reduced. The potential for flooding of adjacent analysis.

areas by water lost through the RHR pump seals and/or RHR heat exchangers prior to isolation does not appear to have been evaluated.

Flooding of adjacent areas could impact additional equipment affecting the ability to achieve a safe, stable condition.

Evaluate the potential volume of water which can be released prior to isolation of the VS sequence with no piping failure to determine if additional mitigation equipment could be affected.

AS-A8-01 Accident Sequences and Event Tree Development Notebook, SA-PRA- AS-A8, AS-B6 Mission times vice recovery of off site power 002, Revision 0 and the associated CAFTA event trees define the end are addressed in the Rev. 4.3 PRA model.

state of each sequence as success or core damage. However, the Documentation to be updated to reflect this.

SBO sequences S08, S11, S14, and S17 are assumed to be No impact on the SAMA analysis.

successful based on offsite power recovery. Operator action to restore mitigating systems after power recovery is not addressed. In addition, given the fact that power recovery is only credible out to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> of mitigating system operation and the potential failures of that equipment over a significant portion of the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> mission time is not being addressed. This failure to address recovery of mitigating systems following power recovery does not ensure a safe, stable end state has been reached for some SBO sequences.

There is also concern that the application of offsite power recovery is included twice in the modeling of the SBO event. Recovery is credited in the application of a diesel mission time of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and again through the application of offsite power recovery top event RBU.

Recovery of offsite power does not guarantee restoration of mitigating systems needed to establish a safe stable condition in the plant. In Page 6 of 24

LR-N10-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard some plant models, operator action to restore required mitigating systems following power recovery has been shown to be significant.

In addition, mitigating system operation over a significant portion of the 24 mission time is not being addressed.

Extend the event tree models to address restoration and operation of required safety functions following offsite power recovery. Potential events to include are decay heat removal and primary inventory makeup.

SC-B5-01 A check of the reasonableness and acceptability of the success criteria SC-B5 This is a documentation consideration only results is not documented. and does not affect the technical adequacy Comparing success criteria results with those of similar plants or of the PRA model. No impact on the SAMA performed using other plant-specific codes provides greater assurance analysis.

that the results are correct.

Document a check of the reasonableness and acceptability of the success criteria results. Supporting requirement SC-B5 provides example methods. Note that the PWROG PSA database identifies success criteria for its constituent plants and may be a helpful resource.

SC-C3-02 Sources of uncertainty are addressed in a draft evaluation using SC-C3, AS-C3, This is a documentation consideration only guidance from draft EPRI report, "Treatment of Parameter and Model HR-D6, HR-G9, and does not affect the technical adequacy Uncertainty for Probabilistic Risk Assessments." HR-13, DA-E3, of the PRA model. No impact on the SAMA An appropriate characterization of uncertainty is required to support QU-E1, QU-E3, analysis.

risk-informed decision making. QU-E4, QU-F4, Apply the EPRI guidance, once finalized, to identify the sources of LE-F2, LE-G4 uncertainty in the analysis.

SY-A4-01 System walkdown documentation not included in the system notebook SY-A4 This is a documentation consideration only documentation. and does not affect the technical adequacy A review of system notebooks and available documentation does not of the PRA model. No impact on the SAMA include system walkdown information. A draft document containing analysis.

photos and documentation of insights from a system walkdown was provided to the peer review but is not finalized.

Finalize the provided notebook.

SY-A6-01 Missing boundary definitions for system models. SY-A6, SY-C2 This is a documentation consideration only The system notebooks do not clearly define the boundaries. The and does not affect the technical adequacy training documentation is not adjusted to be specific to the PRA model. of the PRA model. No impact on the SAMA Additionally some systems, such as AC power, do not include analysis.

discussion of modeled events. The diesel generator and the fuel oil transfer system are not addressed explicitly.

Develop PRA specific illustrations and expand documentation to clearly describe the system boundaries to ensure that no components are double counted or missed.

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LR-N1\0-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard SY-A8-01 Review of notebooks and data notebook did not provide a source for SY-A8 This is a documentation consideration only inclusion or exclusion of failure modes based on data boundaries, and does not affect the technical adequacy No documentation of component boundaries of the PRA model. No impact on the SAMA Expand the data discussion to provide component definitions, analysis.

SY-A10-01 Some systems do not include expected failure modes and although this SY-A10 This is a documentation consideration only may be correct, there is no documentation as to how the data and does not affect the technical adequacy boundaries encompass the expected failures. of the PRA model. No impact on the SAMA One example is the diesel generator model does not include the diesel analysis.

generator day tank and instrumentation. The response to inquiries was that these components are part of the diesel skid package. This is usually separate modeling to capture miscalibrations.

Define what is included within the diesel generator "box" or expand the model.

SY-A12-01 Review of system models identified some missing component failure SY-A12 Components are included in the PRA model modes. either explicitly or as part of a super-Required components are not always addressed in the model. For component. This is a documentation example, the diesel generator day tank and fuel oil check valves are consideration and does not affect the not included. Additionally, restart of some components (such as technical adequacy of the PRA model. No dampers having to re-open for CAV) are absent in the model. impact on the SAMA analysis.

Define boundaries to show incorporation of failure modes by other events or expand model.

SY-A13-01 The modeling excludes some required component failures without SY-A13 This is a documentation issue and does not justification. affect the technical adequacy of the PRA Some failure modes listed for inclusion in the SR are not found or are model. No impact on the SAMA analysis.

excluded from the model. This includes the transfer closed/plugging failure modes for valves and the absence of some check valves and/or tanks.

Justify the exclusion of any failure mode or model the failure mode.

SY-A16-01 The SWS fault tree includes recovery via alignment of the header SY-Al16 Since this impacts only one specific HFE for crosstie. HFE SWS-XHE-FO-OVER2 is used for this recovery action in recovery of SW, it is expected to have only a all cases, even LOOP. However, the timing used in the HRA for this minimal impact on the SAMA analysis and action is based on room heatup following a loss of CAV, not on the the ability to estimate averted cost-risks.

more restrictive timing required for recovery of cooling to a diesel following LOOP.

Application of the HFE for recovery of SW via the header crosstie in the incorrect context may result in underestimating the importance of the HFE and associated equipment required for the recovery.

Create a variation of the SWS-XHE-FO-OVER2 HFE accounting for differences in timing during LOOP conditions where cooling to a diesel generator is required.

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LR-N10-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard SY-Al 9-01 System notebooks do not include discussions on potential adverse SY-A19, SY- This is a documentation consideration only operating conditions that could impact operation. A20 and does not affect the technical adequacy No documentation of any potential for loss of desired system function, of the PRA model. No impact on the SAMA e.g., excessive heat loads, excessive electrical loads, excessive analysis.

humidity, etc.

Add brief discussion.

SY-A21 -01 The current type code does not provide consistent nomenclature for SY-A21, QU- This observation is believed to relate to same failure data. A2b special instances where data are lacking for The SR indicates that the nomenclature should use the same identifier certain component/failure modes (e.g.,

for the same failure mode. The type code changes by system although diesel driven air compressor fails to start).

the data are from the same source. In these cases, data from other similar For data sources from the same reference the same type code should components were used. This is believed to be used. be an appropriate approximation. This issue Using type codes by system may obscure the state of knowledge does not adversely impact the SAMA information. analysis or the ability to estimate averted cost-risks.

SY-B5-01 Documentation indicated that the heated water circulating system was SY-B5 This is a documentation consideration only required. and does not affect the technical adequacy Documentation for several system notebooks (AFW, CVCS and RWST) of the PRA model. No impact on the SAMA indicated that the heated water circulating system was required to analysis.

prevent freezing, but was not modeled.

Model the heated water circulating system or justify the reason for not modeling.

SY-Bi 1-01 Some AFW signals (SI, LOOP) are not defined and no justification for SY-B1 1 This is a documentation consideration only exclusion is provided and does not affect the technical adequacy The SR states that actuation signals must be considered or justification of the PRA model. No impact on the SAMA provided. The AFW start signals are not completely modeled and analysis.

justifications for exclusion are not provided.

Provide justification for exclusion of the AFW signals or model these signals.

HR-C3-01 There is no documentation showing that miscalibration as a mode of HR-C3, SY-B16 Even though these types of pre-initiator failure of initiation of standby systems was considered. An example of human errors may not have been modeled, this is that there is no HFE for miscalibration of bus undervoltage bus, their risk contribution is generally viewed as RPS relays, etc. being relatively low when compared to other There is no documentation showing that miscalibration as a mode of events in the PRA model. Therefore, the failure of initiation of standby systems was considered. An example of impact on the SAMA analysis would be this is that there is no HFE for miscalibration of bus undervoltage bus, minimal and would not adversely affect the RPS relays, etc. ability to estimate averted cost-risks.

Consider analyzing the miscalibration of standby systems.

DA-Al a-01 No discussion of component boundary definition is provided in either DA-Al a, DA-C1 This is a documentation consideration only the data or systems analysis. Boundaries for unavailability events are and does not affect the technical adequacy Page 9 of 24

LR-N 10-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard not established. of the PRA model. No impact on the SAMA Boundary definitions help assure that failures are attributed to the analysis.

correct component and that calculated failure rates and unavailability values are appropriate. Some component boundaries are discussed in the notes to Appendix A, "Generic (Industry) Failure Data" of the Data Notebook. Note 32 states to "Assume that CCW/RHR HX failure rates apply to TDAFW Pump Bearing and governor jacket coolers", however unless the Salem TDAFW pump has unique features that require this to be modeled separately, cooling to the TDAFW pump is usually included in the component boundary to the pump.

Define the component boundary for each component consistent with the failure data source. Establish boundaries for unavailability events consistent with definitions in the svstems analvsis.

DA-Cl-01 Generic unavailability data are used for some SSCs without DA-C1 This is a documentation consideration only demonstrating that the data are consistent with the test and and does not affect the technical adequacy maintenance philosophies for the subject plant. of the PRA model. No impact on the SAMA Generic unavailability data may not be applicable to Salem if its T&M analysis.

approach is different.

Review and state that any generic unavailability data used is applicable to the Salem model.

DA-C2-01 Plant-specific data are only collected for MSPI components. The PRA DA-C2 The majority of high importance systems procedure requires plant specific data to be collected for components were updated with recent plant specific data with a RAW >2 or a F-V greater than 0.005. in the Rev. 4.3 PRA model. No impact on MSPI components are only a subset of the risk-significant components. the SAMA analysis.

Expand collection of plant-specific data to all modeled components or justify why the generic data are applicable.

DA-C6-01 Documentation describing the process of evaluating the number of DA-C6 This is a documentation consideration only plant specific demands for standby components could not be identified. and does not affect the technical adequacy Standby components were identified in Table 1 of the Data Analysis of the PRA model. No impact on the SAMA Notebook and plant specific demands for some of these components analysis.

were listed in Appendix B, however the basis for these numbers of demands was not provided. The draft data procedure states that plant specific data should be estimated by actual counts of hours or demands from logs or counters, use of surveillance procedures to estimate the frequency of demands and run times, or estimates based upon input from the System Engineer.

Failure rates are dependent on an accurate demand count or component importance could be skewed.

Standby components were identified in Table 1 of the Data Analysis Notebook and plant specific demands for some of these components were listed in Appendix B, however the basis for the number of Page 10 of 24

LR-N10-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard demands was not provided. The draft data procedure states that plant specific data should be estimated by actual counts of hours or demands from logs or counters, use of surveillance procedures to estimate the frequency of demands and run times, or estimates based upon input from the System Engineer. Issue the data collection guidance document and document/justify the basis for the demands used.

DA-Ci 0-01 Compare the initiator frequencies used in the Salem model with other DA-C1 0 This is a documentation consideration only generic data sources. and does not affect the technical adequacy This F&O is characterized as a suggestion because the IE notebook of the PRA model. No impact on the SAMA does include a comparison with NUREG/CR-5750. But, it is analysis.

recommended for completeness to check how the Salem set of initiators compares with other data sources.

DA-D4-01 No documentation exists related to the comparison between the DA-D4 This is a documentation consideration only generic value and the plant-specific update value to ensure accurate and does not affect the technical adequacy and meaningful implementation of Bayes approach. The of the PRA model. No impact on the SAMA documentation only indicates that data came from NUREG/CR-6928 analysis.

and that MSPI data was used to perform the update. It then references Appendix B which is only Table B-I. The table provides limited information related to the update and does not provide any comparisons of results or discussions with regard to applicability of results.

The documentation only indicates that data came from NUREG/CR-6928 and that MSPI data was used to perform the update. It then references Appendix B which is only Table B-1. The table provides limited information related to the update and does not provide any comparisons of results or discussions with regard to applicability of results.

Perform comparisons of results with regard to initial ranges of possible generic values and confirmation that the updated results are within the expected range. Also confirmation that plant data, due to relatively small generic alpha factors is not biasing the updated value.

DA-D6-01 No documentation is present that provides any comparisons between DA-D6 This is a documentation consideration only data sources. and does not affect the technical adequacy Perform the evaluation. of the PRA model. No impact on the SAMA analysis.

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LR-N10-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard DA-E2-01 A draft document was provided that documented how to establish DA-E2, DA-C6 This is a documentation consideration only component boundaries, how to establish failure probabilities, sources of DA-C7 and does not affect the technical adequacy generic data, etc. This procedure needs to be formalized. DA-C8 of the PRA model. No impact on the SAMA The draft document discussing how to perform data analyses needs to DA-C9 analysis.

be finalized to ensure quality.

Provide procedure on how to perform data analysis.

QU-B5-01 Salem Quantification Notebook SA PRA-2008-01 Attachment E QU-B5 The convergence issue is addressed in the documents the convergence analysis performed to set an appropriate Rev. 4.3 PRA model. The circular logic truncation value. The truncation level for both CDF and LERF was set issue is judged to be a documentation at 1.OE-1 1. The percentage change between 1.OE-1 0 and 1.OE-1 1 was consideration only and does not affect the 2.2% for CDF, but 6.1% for LERF. Therefore, this SR was not satisfied technical adequacy of the PRA model. No for LERF. impact on the SAMA analysis.

The supporting requirement applies the same criteria for convergence to both CDF and LERF. The criteria were satisfied for CDF, but not LERF.

Document the overall philosophy and method for breaking circular logic in the Quantification notebook and provide sufficient documentation in the system notebooks to provide assurance that unnecessary conservatisms or non-conservatisms are not introduced.

QU-B9-01 Split fractions and undeveloped events are included in the model. QU-B9 This is a documentation consideration only Examples include main feedwater availability for ATWS (MFI- and does not affect the technical adequacy UNAVAILABLE) and some Unit 2 systems credited for recovery of Unit of the PRA model. No impact on the SAMA 1 CAV failure (G2SW22). The derivation of the values for these events analysis.

is not documented.

The derivation of split fractions and undeveloped events is not documented sufficiently to allow identification of shared events and results interpretation based on individual events subsumed into the split fraction.

Document the derivation of any split fractions and undeveloped events used in the model sufficiently to allow results interpretation and to provide assurance that the impact of any shared components is appropriately considered.

QU-D1b-01 There is no discussion in the quantification notebook that indicates a QU-D1b This is a documentation consideration only review of the results was performed for the purpose of assessing and does not affect the technical adequacy modeling and operational consistency. Also, since the sequences were of the PRA model. No impact on the SAMA not quantified, it is difficult to perform this verification. analysis.

This F&O is characterized as a finding because there was insufficient documentation available to verify the SR.

Review the results for modeling consistency (e.g., event sequence models consistency with systems models and success criteria) and operational consistency (e.g., plant configuration, procedures, and Page 12 of 24

LR-N 10-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard plant-specific and industry experience) and include in the quantification notebook.

QU-D3-01 This is a Capability Category 1 because there is no documentation to QU-D3 This is a documentation consideration only indicate that the Salem results were compared to the results of a similar and does not affect the technical adequacy plant. of the PRA model. No impact on the SAMA No documentation was provided showing this requirement was met. analysis.

Provide a comparison of initiating event contributions and significant basic event importances between Salem and similar plants based on information available in the PWROG PRA Comparison Database.

QU-D4-01 There is no documentation indicating that a sampling of non-significant QU-D4 This is a documentation consideration only accident cutsets or sequences were reviewed to determine they are and does not affect the technical adequacy reasonable and have physical meaning. of the PRA model. No impact on the SAMA Quantification Notebook Section 2 only requires a review of the top 100 analysis.

cutsets. Review of a sampling of non-significant cutsets can also reveal logic problems or recovery rules which are not being applied correctly.

Include a requirement for review of a sampling of non-significant sequences in Section 2 of the Quantification Notebook and in procedures governing the model update process.

QU-F2-01 This requirement was only partially met as described below: QU-F2, QU-F3, This is a documentation consideration only

- (a) This requirement is met by the system and HRA notebooks. QU-F6 and does not affect the technical adequacy (b) There is a cutset review process description. of the PRA model. No impact on the SAMA (c) There is no description of how the success systems are analysis.

accounted for. Since a one top tree is used the software already accounts for this. A statement stating would be satisfactory. The truncation values and how they were determined were documented. The method for applying recovery and how post initiator HFE's are applied was not described.

(d) This requirement was met.

(e) This requirement was met.

(f) This requirement was not met since the cutsets per accident sequence were not discussed.

(g) This requirement was not met since equipment or human actions that are the key factors in causing the accidents sequences to be are not discussed.

(h) This requirement was not met since sensitivities were not documented.

(i) This requirement was not met since the uncertainty notebook was not finalized.

(j) This requirement is not met since there is no discussion of Page 13 of 24

LR-N10-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard importance.

(k) This requirement is not met because there is not list of mutually exclusive events and there justification.

(I) This requirement is not met because there is no discussion of asymmetries in quantitative modeling to provide application users the necessary understanding regarding why such asymmetries are present in the model.

(m) This requirement is met since CAFTA and Forte are being used. Both of these pieces of software are industry standards and therefore no further testing is required.

Several documentation items called for in this supporting requirement were not available for review. Specific items not included in the documentation were: the process used to account for system successes, accident sequence results, discussion of factors causing accidents to be non-dominant, sensitivity assessments, uncertainty distribution, importance measure results, basis for elimination of mutually exclusive events, asymmetries in the model, and a quantitative definition of significant basic event, significant cutset, and significant accident sequence.

Expand the documentation to address the items documented in the F&O.

LE-C8a-01 Equipment survivability and human actions under adverse LE-C8a, LE- No credit is taken for equipment or actions environments must be considered to reach Category 2. C8b, LE-C9a, under adverse environments. This is a No documentation provided or credit taken for equipment or operators LE-C9b documentation consideration only and does in adverse environment. not affect the technical adequacy of the PRA Provide discussion on environmental conditions and the effects on model. No impact on the SAMA analysis.

operator actions.

LE-Fl b-01 Other than verifying that the sum of the three end states (INTACT, LE-Fi b This is a documentation consideration only LATE and LERF) is approximately equal to the core damage frequency, and does not affect the technical adequacy no checks on the reasonableness of the LERF contributors is of the PRA model. No impact on the SAMA documented. analysis.

A review for reasonableness is required to meet the intent of this SR.

Review contributors for reasonableness (e.g., to assure excessive conservatisms have not skewed the results, level of plant specificity is appropriate for significant contributors, etc.).

Page 14 of 24

LR-N 10-0309 Enclosure Table 1-1 Identified Gaps to Capability Category 2 or 3 of the ASME PRA Standard LE-F3-01 _ LERF uncertainties are not characterized consistent with the LE-F3 This is a documentation consideration only requirements in Tables 4.5.8-2(d) and 4.5.8-2(e). and does not affect the technical adequacy LERF uncertainties must be appropriately characterized to meet the of the PRA model. No impact on the SAMA intent of this SR. analysis.

Characterize the LERF uncertainties consistent with the requirements in PRA Standard Tables 4.5.8-2(d) and 4.5.8-2(e).

LE-G5-01 Limitations in the LERF analysis that would impact applications are not LE-G5 This is a documentation consideration only documented. and does not affect the technical adequacy Limitations in the LERF analysis that would impact applications must be of the PRA model. No impact on the SAMA discussed to meet this SR. analysis.

Document the limitations in the LERF analysis that would impact applications.

LE-G6-01 A definition for significant accident progression sequence is not LE-G6 This is a documentation consideration only documented. and does not affect the technical adequacy A definition for significant accident progression sequence must be of the PRA model. No impact on the SAMA included to meet this SR. analysis.

Include in the documentation a definition for significant accident progression sequence.

References:

ASME 2005 ASME (The American Society of Mechanical Engineers). 2005. ASME RA-Sb-2005, Addenda to ASME RA-S-2002 Standard for Probabilistic Risk Assessment for Nuclear Power Plant Applications. December.

NRC 2007a Regulatory Guide 1.200, An Approach for Determining the Technical Adequacy of ProbabilisticRisk Assessment Results for Risk Informed Activities, Revision 1, January 2007.

NRC 2007b U.S. Nuclear Regulatory Commission Memorandum to Michael T. Lesar from Farouk Eltawila, "Notice of Clarification to Revision 1 of Regulatory Guide 1.200", July 27, 2007.

Page 15 of 24

LR-N 10-0309 Enclosure

2. Clarification requested regarding RAI 5.b.

PSEG provided a revised basic events importance list based on an updated PRA model (MOR Rev. 4.3) and correlated the important events to existing SAMAs for all but three basic events. For these three basic events, PSEG identified new SAMAs and provided a cost-benefit analysis of each using the MOR Rev. 4.3 PRA model. The response to RAI 1.d states that the updated MOR Rev. 4.3 has an internal events CDF of 2.20E-05 /yr compared to 4.77E-05 /yr for MOR Rev. 4.1 used in the SAMA analysis and that this reduction is due to plant design and procedure changes. Clarify whether any of the PRA model changes since MOR Rev. 4.1 may have increased the risk significance of the MOR Rev. 4.1 important basic events and, if so, assess the impact on the SAMA evaluation (i.e., would any SAMAs previously determined to not be cost-beneficial become cost-beneficial if their benefits were assessed based on MOR Rev. 4.3?).

PSEG Response:

Averted costs were calculated and the net benefit quantified using the Rev. 4.3 PRA model for several of the SAMAs identified in the original SGS License Renewal Environmental Report, as well as the three new SAMAs identified from the Rev. 4.3 PRA model importance list review. The 9 5 th percentile results using the Rev. 4.3 PRA model are tabulated below in Table 2-1 and compared to the original net values that were calculated using the Rev. 4.1 PRA model.

No SAMAs previously determined to not be cost-beneficial became cost-beneficial when assessed using the Rev. 4.3 PRA model. Those SAMAs identified in the original SGS License Renewal Environmental Report that were evaluated using the Rev. 4.1 PRA model and were found to not be cost beneficial were not re-quantified using the Rev. 4.3 PRA model, since the changes made to produce the Rev. 4.3 PRA model would have minimal impact on these SAMAs. Table 2-2 provides a listing of these SAMAs and the justification as to why they would remain not cost beneficial, thus not requiring them to be re-quantified using the Rev. 4.3 PRA model.

Page 16 of 24

LR-N10-0309 Enclosure TABLE 2-1 COMPARISON OF AVERTED COST RISKS BETWEEN THE R4.1 AND R4.3 PRA MODELS SAMA ID COST OF 9 5 TH NET VALUE (R4.1 9 5 TH NET VALUE IMPLEMENTATION PERCENTILE MODEL) PERCENTILE (R4.3 MODEL)

AVERTED AVERTED COST-RISK COST-RISK (R4.1 MODEL) (R4.3 MODEL)

SAMA1 $475,000 $11,960,631 $11,485,631 $2,360,208 $1,885,208 SAMA2 $875,000 $4,001,975 $3,126,975 $1,818,798 $943,798 SAMA3 $4,175,000 $5,986,200 $1,811,200 $2,947,327 -$1,227,673 SAMA4 $585,000 $5,961,020 $5,376,020 $3,059,114 $2,474,114 SAMA5 $3,320,000 $7,643,895 $4,323,895 $2,758,498 -$561,502 SAMA6 $250,000 $750,315 $500,315 $1,006,749 $756,749 SAMA7 $470,000 $1,028,610 $558,610 $1,432,236 $962,236 SAMA8 $2,510,000 $4,119,803 $1,609,803 $5,653,569 $3,143,569 SAMA9 $1,235,000 $4,256,415 $3,021,415 $1,643,943 $408,943 SAMA10 $100,000 $276,410 $176,410 $346,443 $246,443 SAMA11 $100,000 $4,997,310 $4,897,310 $6,824 -$93,176 SAMA12 $475,000 $1,375,390 $900,390 $1,951,377 $1,476,377 SAMA14 $485,000 $1,326,220 $841,220 $81,979 -$403,021 SAMA17 $200,000 $1,265,450 $1,065,450 $393,288 $193,288 SAMA 24 $175,000 $1,753,580 $1,578,580 $2,688,053 $2,513,053 SAMA27 $4,230,000 $7,746,828 $3,516,828 $2,816,571 -$1,413,429 SAMA30 $100,000 N/A N/A $82,925 -$17,075 SAMA31 $100,000 N/A N/A $56,287 -$43,713 SAMA32 $250,000 N/A N/A $104,566 -$145,434 Page 17 of 24

LR-N10-0309 Enclosure TABLE 2-2 JUSTIFICATION FOR SAMAS NOT BEING RE-QUANTIFIED USING THE REV. 4.3 PRA MODEL SAMA SAMA TITLE SAMA DESCRIPTION COST COST COST JUSTIFICATION NO. ESTIMATE BENEFICIAL IN BENEFICIAL SAMA USING REV. 4.3 SUBMITTAL PRA MODEL (YES [Y] OR NO (YES [Y] OR

[N]) NO [N])

13 Install Primary The availability of primary side $17,750,000 N N Cost estimate exceeds 95th percentile Side Isolation steam generator isolation valves MACR.

Valves on the would provide a simple means of Steam isolating ruptured SGs. While Generators secondary side isolation capability exists, these valves would help avoid challenges to secondary side integrity due to failure to rapidly cool down the primary side.

15 Automate RCP CCW cools the letdown and seal $210,000 N N The same contributors would be active and Seal Injection water return heat exchangers which with the reduction in the EE PACR due to the Re-alignment on will raise VCT temperature and overall CDF reduction, the SAMA would Loss of CCW ultimately result in overheated RCP remain not cost beneficial.

seals if charging continues to take suction from the VCT. This HEP models the operator action to isolate letdown and transfer charging pump suction to the RWST. If Charging suction is not transferred prior to reaching 225 'F, the sudden lowering of the seal water injection temperature from the RWST could cause the RCP seals to crack and fail. In addition, as CCW cools the positive displacement charging pump (13) which is normally in service, the Loss of CCW procedure directs that the 11 or 12 charging pump be placed in service as their oil coolers use SW. Automating the isolation of the letdown line, the swap to a CCP, and the suction source alignment to the RWST Page 18 of 24

LR-N10-0309 Enclosure TABLE 2-2 JUSTIFICATION FOR SAMAS NOT BEING RE-QUANTIFIED USING THE REV. 4.3 PRA MODEL SAMA SAMA TITLE SAMA DESCRIPTION COST COST COST JUSTIFICATION NO. ESTIMATE BENEFICIAL IN BENEFICIAL SAMA USING REV. 4.3 SUBMITTAL PRA MODEL (YES [Y] OR NO (YES [Y] OR

[N]) NO [N])

could reduce the risk of seal LOCAs.

16 Install an While Salem already has a $2,535,000 N N Not cost beneficial by a large margin. This Additional Train reasonably reliable action to provide SAMA is expected to remain not cost of Switchgear alternate cooling to the switchgear beneficial.

Room Cooling rooms, loss of cooling is still a Equipment significant contributor to risk.

Further reductions in loss of switchgear room cooling contributions would require the installation of an additional train of cooling that would operate automatically on loss of cooling.

18 Automate In cases where fewer Service Water $635,000 N N This was a low cost-benefit SAMA, and with Turbine Header pumps are available than required the reduction in the EE PACR due to the Isolation in the for cooling the safety related loads, overall CDF reduction, it would remain not Service Water the turbine header isolation function cost beneficial.

System on Low could be enhanced by installing Pump Discharge another isolation valve, such as an Pressure MOV, in series that is powered by a different electrical train so as to ensure redundancy and reliability.

19 Install Spray The installation of spray shields for $350,000 N N This was a low cost-benefit SAMA, and with Shields on the the RHR pumps in the Aux. Building the reduction in the EE PACR due to the RHR Pumps 45' el. area would provide the overall CDF reduction, it would remain not necessary protection against any cost beneficial.

damaging spray scenario, and thus would allow functionality of these pumps. Spray scenarios, by virtue of their flow rate being < 100 gpm, would not likely threaten the operability and functionality of the ruptured water system providing the Page 19 of 24

LR-N10-0309 Enclosure TABLE 2-2 JUSTIFICATION FOR SAMAS NOT BEING RE-QUANTIFIED USING THE REV. 4.3 PRA MODEL SAMA SAMA TITLE SAMA DESCRIPTION COST COST COST JUSTIFICATION NO. ESTIMATE BENEFICIAL IN BENEFICIAL SAMA USING REV. 4.3 SUBMI'TAL PRA MODEL (YES [Y] OR NO (YES [Y] OR

[N]) NO [N])

source of spray in this area.

20 Fire/Seismic A potential option to mitigate fires $13,100,000 N N Cost of implementation is greater than the Safe System for that cause damage across multiple MACR.

Primary and trains and systems would be to Secondary install two engine driven pumps that Inventory can be controlled locally to provide Control makeup to the RCS and steam generators. These systems would not rely on any other systems for success and while they may be relatively difficult to operate, they would provide a path for success when other makeup options are not available. The RCS makeup pump would require a suction connection to the RWST and an injection connection through the safety injection lines (outside containment, but downstream of the MOVs). For the secondary side makeup pump, suction would be required from the fire water system and injection through the turbine driven AF pump line. Ensuring the equipment is seismically qualified and stored in a seismically qualified structure would also provide a means of mitigating seismic events that cause widespread system failures.

21 Seal the The dominant fire scenario in the $3,230,000 N N While the EE multiplier went up, the fire Category 2 and Relay Room (IFA-AB-100A) is a PACR went down due to the overall CDF 3 Cdbinets in the cabinet fire that is not suppressed reduction and the averted cost-risk would Page 20 of 24

LR-N10-0309 Enclosure TABLE 2-2 JUSTIFICATION FOR SAMAS NOT BEING RE-QUANTIFIED USING THE REV. 4.3 PRA MODEL SAMA SAMA TITLE SAMA DESCRIPTION COST COST COST JUSTIFICATION NO. ESTIMATE BENEFICIAL IN BENEFICIAL SAMA USING REV. 4.3 SUBMITTAL PRA MODEL (YES [Y] OR NO (YES [Y] OR

[N]) NO [N])

Relay Room and is able to propagate to the point also decrease accordingly.

where it is large enough to force main control room abandonment.

The issue for this scenario is not necessarily the availability of equipment, but more that the operators are forced to take control of the plant from the RSP. The most effective method identified to reduce the risk from this scenario is to provide better barrier separation for cabinet fires in this area in order to reduce the threat of fire propagation from one cabinet to another. What this would involve includes the means of providing fire barrier and adequate cabinet/train separation so as to minimize the unavailability of both safety related trains due to fire propagation. This would involve the modification of several cabinets within the relay room. It was estimated that 48 out of 68 cabinets in the room would require protection using an approved fire barrier material. This SAMA would not involve installation or modification of any new or existing fire detection or suppression equipment.

22 Install Fire The largest contributors to fires in $1,600,000 N N While the EE multiplier went up, the fire Barriers the CRE are those that force PACR went down due to the overall CDF Between the abandonment of the CRE due to reduction and the averted cost-risk would 1CC1, 1CC2, damage in the 1CC1, 1CC2, and/or also decrease accordingly.

Page 21 of 24

LR-N10-0309 Enclosure TABLE 2-2 JUSTIFICATION FOR SAMAS NOT BEING RE-QUANTIFIED USING THE REV. 4.3 PRA MODEL SAMA SAMA TITLE SAMA DESCRIPTION COST COST COST JUSTIFICATION NO. ESTIMATE BENEFICIAL IN BENEFICIAL SAMA USING REV. 4.3 SUBMITTAL PRA MODEL (YES [Y] OR NO (YES [Y] OR

[N]) NO [N])

and 1CC3 1 CC3 consoles. The most effective Consoles in the means of reducing the CDF of these CRE scenarios is considered to be preventing the need to abandon the CRE. Using an approved fire barrier material within these cabinets is one method of reducing the likelihood of having a fire in one cabinet propagate to another cabinet. The prevention of a fire from causing damage to one of the other two cabinets will help to reduce the need to abandon the MCR. This SAMA would not involve installation or modification of any new or existing fire detection or suppression equipment.

23 Install Fire Rooms that include cable or $975,000 N N While the EE multiplier went up, the fire Barriers and equipment for multiple divisions PACR went down due to the overall CDF Cable Wrap to introduce the undesirable situation reduction and the averted cost-risk would Maintain in which a single fire event can also decrease accordingly.

Divisional disable multiple divisions of Separation in the equipment. Given the importance of 4160V AC the 4160V AC equipment, the Switchgear cables and equipment in the 4160 Room Switchgear room should be protected to prevent the propagation of a fire from one division to another.

Page 22 of 24

LR-N10-0209 Enclosure ACRONYMS AND ABREVIATIONS ACRONYM OR ABREVIATION DEFINITION AC alternating current AFW auxiliary feed water ASME American Society of Mechanical Engineers ATWS anticipated transient without scram CAV control area ventilation CCPs component cooling pumps CCW component cooling water CDF core damage frequency el. elevation EPRI Electric Power Research Institute ESFAS engineered safety features actuation system F-V Fussell-Vesely F&O fact and observation gpm gallons per minute HEP human error probability HFE human failure event ISLOCA interfacing system loss of coolant accident LERF large, early release fraction [or frequency]

LOCA loss of coolant accident LOOP loss of offsite power MACR maximum averted cost risk MOV motor operated valve MSPI mitigating systems performance index NRC Nuclear Regulatory Commission Page 23 of 24

LR-N1 0-0209 Enclosure ACRONYMS AND ABREVIATIONS ACRONYM OR ABREVIATION DEFINITION PACR partial averted cost-risk PCs power conversion system PCS process control system PORV power operated relief valve PRA probabilistic risk assessment PSA probabilistic safety assessment PWROG Pressurized Water Reactor Owners Group RAI request for additional information RAW reliability achievement worth RCP reactor coolant pump RG Regulatory Guide RHR residual heat removal RPS reactor protection system RWST refueling water storage tank SAMA severe accident mitigation alternative SG steam generator SGS Salem Generating Station SI safety injection SW service water SR supporting requirement SSCs structures, systems, and components TDAFW turbine-driven auxiliary .feedwater pump T&M test and maintenance VCT volume control tank Page 24 of 24