Text

Response to Request for Additional Information, NextEra Energy Seabrook License Renewal Application
	ML11122A075
Person / Time
Site:	Seabrook
Issue date:	04/18/2011
From:	Freeman P; NextEra Energy Seabrook
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	SBK-L-11067
	Download: ML11122A075 (73)
	v • d • e

NEXTera ENERG-jY&A ES April 18, 2011 SBK-L-1 1067 Docket No. 50-443 U.S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 Seabrook Station Response to Request for Additional Information NextEra Energy Seabrook License Renewal Application

References:

1. NextEra Energy Seabrook, LLC letter SBK-L-10077, "Seabrook Station Application for Renewed Operating License," May 25, 2010. (Accession Number ML101590099)

2. NRC Letter "Request for Additional Information for the Review of the Seabrook Station License Renewal Application-SAMA Review (TAC NO. ME3959) November 16, 2010.

(Accession Number ML103090215)

3. NextEra Energy Seabrook, LLC letter SBK-L-11001, "Seabrook Station Response to Request for Additional Information, NextEra Energy Seabrook License Renewal Application," January 13, 2011. (Accession Number ML110140810)

4. NRC Letter "Schedule Revision and Request for Additional Information for the Review of the Seabrook Station License Renewal Application Environmental Review (TAC Number ME3959) March 4, 2011. (Accession Number ML110590638)

In Reference 1, NextEra Energy Seabrook, LLC (NextEra) submitted an application for a renewed facility operating license for Seabrook Station Unit 1 in accordance with the Code of Federal Regulations, Title 10, Parts 50, 51, and 54.

Nx4 NextEra Energy Seabrook, LLC, P.O. Box 300, Lafayette Road, Seabrook, NH 03874

United States Nuclear Regulatory Commission SBK-L-1 1067 / Page 2 In Reference 2, the NRC requested additional information in order to complete its review of the License Renewal Application. In Reference 3, NextEra submitted its responses to the staffs RAls.

In reference 4 the staff identified areas where additional information is necessary to complete the SAMA review. The Enclosure contains the NextEra Energy Seabrook response to the NRC request for additional information dated March 4, 2011. There are no new or revised commitments made in this submittal.

The License Renewal Application, Appendix E, page F-6 contains a list of acronyms used in these responses. If there are any questions or additional information is needed, please contact Mr. Richard R. Cliche, License Renewal Project Manager, at (603) 773-7003.

If you have any questions regarding this correspondence, please contact Mr. Michael O'Keefe, Licensing Manager, at (603) 773-7745.

Sincerely, NextEra Energy Seabrook, LLC.

Paul Freeman Site Vice President Enclosure cc:

W.M. Dean, NRC Region I Administrator G. E. Miller, NRC Project Manager, Project Directorate 1-2 W. J. Raymond, NRC Resident Inspector R. A. Plasse Jr., NRC Project Manager, License Renewal M. Wentzel, NRC Project Manager, License Renewal Mr. Christopher M. Pope Director Homeland Security and Emergency Management New Hampshire Department of Safety Division of Homeland Security and Emergency Management Bureau of Emergency Management 33 Hazen Drive Concord, Ni 03305 John Giarrusso, Jr., Nuclear Preparedness Manager The Commonwealth of Massachusetts Emergency Management Agency 400 Worcester Road Framingham, MA 01702-5399

United States Nuclear Regulatory Commission SBK-L-1 1067 / Page 3 NEXTeraN ENERGY, -

SEABROK I, Paul 0. Freeman, Site Vice President of NextEra Energy Seabrook, LLC hereby affirm that the information and statements contained within are based on facts and circumstances which are true and accurate to the best of my knowledge and belief.

Sworn and Subscribed Before me this

//1!Iday of . A 2011 Paul 0. Freeman Site Vice President Notary Pudlic

Enclosure to SBK-L-11067 NextEra Energy Seabrook Responses to Supplementary NRC Request for Additional Information Regarding Severe Accident Mitigation Alternatives Analysis

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure SAMA Supplemental RAI 1 The responses to RAI 1.f and 2.e state that Tables F.3.1.1.1-2 and F.3.2.1-2 consider initiating events. However, Tables F.3.1.1.1-2 and F.3.2.1-2 show only basic events, and so it is not clear how initiating events are explicitly considered in the importance analysis. For example, the most dominant initiating event contributor according to the listing in Table F.3.1.1 .1-1 is loss of offsite power due to weather (LOSPW), but there appears to be no corresponding event in Tables F.3.1.1.1 -

2 or F.3.2.1-2. Additionally, the responses to RAI .f and 2.e state that Attachment F.A describes a number of SAMA probabilistic risk assessment (PRA) cases that specifically addressed initiating events. While this is the case, it is unclear if all of the dominant initiating events in Table F.3.1.1.1 -1 are addressed. For example, while Attachment F.A describes "NOLOSP" as the modeling case used to determine the benefit of eliminating all Loss of Off-Site Power (LOSP) events, none of the SAMAs evaluated using this case (i.e., SAMAs 13, 14, 16, 24, and 156) specifically addressed initiating event FLLP, "Flood in Turbine Building (causing LOSP)." Other examples from Attachment F.A are PRA cases "FIRE 1" and "FIRE2," which are the PRA model cases used to determine the benefit of eliminating control room induced LOCA and fire in Turbine Building causing loss of power to emergency buses, respectively. Neither of these modeling cases addresses the specific scenario of a fire in Switchgear Rooms A or B and no SAMAs were identified or developed to specifically address fire in Switchgear Rooms A and B. Please provide an explanation, including a table, which correlates SAMA candidates to each of the risk-important initiating events and identifies whether there are any potentially lower cost plant-specific SAMA candidates for the specific initiating events identified. Include, as an example, a demonstration in Tables F.3.1.1.1-2 and F.3.2.1-2 of how LOSPW is considered.

NextEra Energy Seabrook Response to SAMA Supplemental RAI 1 As noted in the Seabrook responses to RAIs 1.f and 2.e (Reference 3), the determination of basic event risk reduction worth (RRW) presented in Tables F.3.1.1.1-2 and F.3.2.1-2 (Reference 1) specifically includes consideration of all initiating events listed in Table F3.1.1.1-1 (Reference 1).

For example, the initiator contributing the most to CDF in Table F.3. 1.1.1-1 is LOSPW - weather-related loss of offsite power. Among the components that are important for mitigating LOSPW are the turbine-driven EFW pump and the EDGs, as demonstrated in the basic event RRW listing of Tables F.3.1.1.1-2 and F.3.2.1-2. The RRW of the basic events associated with the turbine-driven EFW pump and EDG considers all initiating events where these basic events are credited for mitigation. This includes as an example, all loss of offsite power events including; loss of offsite power due grid-related events (LOSPG, loss of offsite power due to hardware or maintenance (LOSPP) or loss of offsite power as a result of turbine building flooding (FLLP). Therefore the basic event SAMA review performed in RAI 5.b of Reference 3 specifically includes consideration of initiating events for which the basic event is credited for mitigation.

Table 1A is provided below to correlate possible SAMA candidates to the top ten risk-important initiating events and identify whether there are any potentially lower cost plant-specific SAMA candidates for these specific initiating events. Based on the Table 1A assessment, no additional cost-beneficial SAMA candidates are identified.

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United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure Table X-1 SAMA Assessment of Top 10 Initiating Events FInitiator Initiating ICDF F FPRA Associated SAMA(s)

AI Assessment Disposition Event Description Case(s)

2 - Replace lead-acid batteries with fuel NOLOS NOLOSP The NOLOSP case conservatively maximizes the benefit by cells P $335K (nom. assuming that the core damage risk contribution from weather benefit) (LOSPW), grid (LOSPG) and plant (LOSPP) loss of offsite

9 - Provide an additional diesel power events is eliminated.

$638K (UB generator (complete - SEPS) benefit)

10 - Bypass DG trips (complete - non- OECR Red: -43%

essential trips bypassed during emergency start)

13 - Install additional buried offsite power source The NOSBO case conservatively maximizes the benefit by assuming that the emergency AC power supplies (EDGs) do not

14 - Install gas turbine NOSBO $155K (nominal fail. NOSBO SAMAs are not cost beneficial based on assumed

16 - Improve uninterruptible power benefit) elimination of all EDG failures

$295K (UB benefit) supplied OECR Red: -14%

20 - Add new backup source of diesel SAMAs #9, #10, #155 and #160 have already been addressed cooling by Seabrook.

Loss of offsite

24 - Bury offsite power lines The remaining SAMA candidates are judged to be not cost

1 - power due to 10.0 beneficial and are not sensitive to an increase in seismic risk as LOSPW weather-related # 154 - Modify SEPS to accommodate addressed below in RAI 4.

events auto bus alignment and loading It is noted that Seabrook Station is nearing completion of a

155 - Install swing DG (complete - multi-phase, multi-million dollar, comprehensive project to SEPS) improve the reliability of the electrical switchyard. These switchyard upgrades will enhance the reliability of offsite power

156 - Alternate offsite source, bypass and should result in an overall reduction in loss of offsite power switchyard initiating event frequency.

160 - SF6 enhancements (complete)

161 - EDG alternate cooling water source

190 - Add synchronization capability to SEPS DG Basic event SAMAs addressed in Tables X-3 through X-7 also apply to this initiating event.

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United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure Table X-1 SAMA Assessment of Top 10 Initiating Events Initiating Initiator PRA Event Description CDF Associated SAMA(s) Case(s) Assessment Disposition SAMA - Improve overall Seabrook Station RXTI $41K (nominal Modifications to reduce/eliminate reactor trip risk are judged reliability; reduce potential for plant trip benefit) not cost beneficial based on assumed complete elimination of initiating event frequency or reliability of $77.3K (UB benefit) . .. p initiator RXT1. The cost benefit is not sensitive to the assumed Cost: >$250K increase in seismic risk evaluated below in RAI 4.

2 - Reactor trip with It is noted that Seabrook Station is nearing completion of a RXTI condenser 6.4% multi-phase, multi-million dollar project to install a digital available feedwater control system and digital electro-hydraulic control Basic event SAMAs addressed in Tables system. These upgrades will replace obsolete components and X-3 through X-7 apply to this initiating enhance the reliability of the existing control systems and event, should result in an overall reduction in reactor trip initiating event frequency.

Reduce/eliminate impact of 0.7g seismic E7T $31.2K (nom.

event (PRA Case E7T). benefit)

$59.3K (UB benefit)

OECR Red: -2%

Cost: >$500K PRA Case E7T conservatively assumes complete elimination of SEISMI $102.4K (nom. this initiating event. E7T contributes 6.3% of the total CDF.

181 - Improve relay chatter fragility CO1 benefit) Based on the conservative PRA case, modifications to eliminate

3 - Seismic 0.7g 6.3% $195K (UB benefit) or reduce this contribution are judged not cost beneficial. The E7T transient event OECR Red: -17% cost benefit is not sensitive to the assumed increase in seismic risk evaluated below in RAI 4.

182 - Improve seismic capacity of EDGs and EFW SEISMI <$1K (nom. benefit)

C02 <$1K (UB benefit)

Basic event SAMAs addressed in Tables OECR Red: 0%

X-3 through X-7 apply to this initiating event.

Loss of offsite

4 - power due to LOSPG grid-related 6.2% Refer to #1 Refer to Refer to #1 LOSPG included in NOLOSP, therefore refer to # 1 events

5 - Seismic og 59% Refer to #3 Refer to Refer to #3 E7T bounds E1OT; therefore refer to #3 EOT transient event 0 1 eerto#3 4 of 15

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure Table X-1 SAMA Assessment of Top 10 Initiating Events Initiating Enti Initiator PRA Descrition CDF Associated SAMA(s) CA Assessment Disposition Event Description Case(s)

Loss of offsite power due to

6 plant 5.6% Refer to#1# Refer to Refer to # 1 LOSPP included in NOLOSP, therefore refer to # 1 LOSPP hardware or maintenance Plant improvements related to SAMA # 183 were identified via the Seabrook IPE (1991). As a result improvements to the turbine building flood alarms and operator response have

183 -Turbine building internal flooding # 183 Improvements occurred since the IPE. Procedure OS1238.02, Turbine improvements. have been addressed Building Flooding, was improved to include specific operator actions and required timing to mitigate a major flood event as a result of postulated failure of a CW system expansion joint.

Protect relay room from potential impact from Actions are initiated based on flood alarms: condenser pit flood HELB (a) F4TREL $22K (nom. benefit) hi level alarm, condenser pit flood hi-hi level alarm,. and turbine

$41.8K (UB benefit) building sump no. I level hi-hi alarm. Other indications OECR Red: -2% include loss of condenser vacuum and reports of circulation

7 Flood in turbine 4.2% Cost: >$100K water flooding conditions in the turbine building. For a major FLLP building - LOSP flood event, actions include tripping the reactor, opening the turbine building rollup doors, closing doors to the relay room Basic event SAMAs addressed in Tables X-3 and emergency switchgear room E5 (these doors are normally through X-7 apply to this initiating event. closed) and tripping CW pumps.

(a) The preliminary SSPSS2010 model, which includes the latest internal flood model and insights, was reviewed as part of this RAI response. The dominant TB flood event is postulated HELB impact to the relay room. Based on PRA case F4TREL, no additional potentially cost beneficial SAMAs are identified to reduce TB flood risk and this result is not sensitive to the increase in seismic risk.

Evaluated in Reference 3, RAI 2.f, item #15 in Table RC LL3, basic event EDESWG6.FX. The E6S PRA case assumes no Loss of Train B failures of Bus E6 that would cause an initiating event during

8 essential AC Improve Bus E6 reliability, eliminate power operation, and no failures of Bus E6 as a support system.

LACPB power (4kV Bus 4.1% potential for bus fault. E6S $39K (nom. benefit) SAMA candidate not cost beneficial based on benefit when E6) $74. I K (UB benefit) assuming elimination of all Bus E6 faults verses SAMA OECR Red: -2% estimated cost and this result is not sensitive to the increase in Cost: >$200K seismic risk.

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United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure Table X-1 SAMA Assessment of Top 10 Initiating Events Initiating Enti Initiator PRA Descrition CDF Associated SAMA(s) CA Assessment Event Description Case(s) Disposition

119 - Institute maintenance practice to perform 100% inspection of SG tubes during each refueling

121 - Increase pressure capacity of secondary side so that a SG tube rupture would not cause the relief valves to lift

125 - Route discharge from the MS safety $86.1 K (nom. SAMA candidates are not cost beneficial based on benefit when

9 Steam Generator valves through a structure where water spray NOSGT benefit) assuming elimination of all SGTR events verses SAMA SGTR% would condense steam and remove fission R $164K (UB benefit) estimated costs and this result is not sensitive to the increase in products OECR Red: -14% seismic risk as addressed below in RAI 4.

126 - Install a highly reliable (closed loop) Cost: >$500K SG shell-side heat removal system

129 - Vent MS safety valves in containment Basic event SAMAs addressed in Tables X-3 through X-7 also apply to initiating events.

Improve/reduce the core damage frequency FSGBE6 $14.4K (nom. SAMA PRA case eliminates fire initiator FSGBE6, fire in contribution of Switchgear Room B fire benefit) Switchgear B resulting in loss of electrical bus E6, to events. $27.6K (UB benefit) conservatively assess the benefit of possible SAMAs to reduce OECR Red: -1% the fire frequency and core damage consequence. FSGBE6 is Cost: >$100K not a significant contributor to CDF. As stated in RAI Ii of Basic event SAMAs addressed in Tables X-3 reference 3, the fire ignition frequency for scenario FSGBE6 is through X-7 also apply to initiating events. based on the total ignition frequency for Bus E6 (21 cubicles) and other electrical cabinets (86 cabinets) located in the "B" switchgear room. Bus E6 cabinets are a fixed combustible and

10 Fire Switchgear fire within the bus is assumed to fail the bus. Other electrical B - Loss of Bus 2.6% cabinets located in the switchgear room are also a fixed E6 combustible. Fire in these other cabinets has a potential to raise the room temperature and jeopardize operation of the various electrical components within the room. Switchgear Room B is separated from Switchgear Room A with a 3 hour3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months fire barrier.

Given the safety system electrical separation, it is concluded that there are no practical, cost-beneficial SAMAs that would significantly reduce the fire-risk contribution of FSGBE6. This conclusion is also relevant for initiator FSGAE5 in Switchgear Room A (Bus E5) and is not sensitive to the increase in seismic risk as addressed below in RAI 4.

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United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure SAMA Supplemental RAI 2a Concerning the NextEra response to staff RAI 3.b:

a. Relative to the FIVE fire risk analysis methodology, clarify if fire-induced failures of components or human actions credited for mitigating the initiator are assessed, given that the initiator is now fire-induced (including identifying either new components or actions to be modeled or requantifying the random failure probabilities of previously modeled ones). In addition, clarify if hot shorts are considered and, if so, what probabilities are assigned to these. If the assigned probabilities are not bounded by currently accepted values (e.g., best estimates of 0.3 and 0.6, respectively, for intra-cable hot shorts for circuits protected vs. not protected by control power transformers in Tables 10-1 through 10-5 of NUREG/CR-6850

[2005], which are based on Electric Power Research Institute (EPRI) 1006961 [2002]), either provide a technical basis for the values assumed (such as circuit analysis) or perform a sensitivity evaluation using the currently accepted values to determine the effect on the potential cost-benefit of the SAMAs.

NextEra Energy Seabrook Response to SAMA Supplemental RAI 2a Fire initiators that are not screened are evaluated in detail to determine fire sequences and to quantify associated core damage. The quantification of fire-induced events considers the following:

" Fire ignition frequency (events/year)

" Fire severity factor for the specific source

" Conditional probability of target damage given a fire, depending on the presence of the combustible in the critical location and on the success of suppression

Probability of additional failures needed for core damage; this includes unavailability of redundant systems/components, failure of operator actions and recovery actions.

Components that are not impacted by the fire are modeled as random, subsequent failures. For example, fire initiating event FSGBE6 is a fire in SWGR-B, which causes an assumed guaranteed loss of Emergency Bus 6 (Train B). Subsequent random failures, which must also occur to achieve core damage include failures of Train A support system components, such as AC power, service water, PCCW. No new components or actions are identified for re-quantification.

As mentioned in the RAI 3b response, fire initiating events are reviewed in detail and some were screened based on their total fire event frequency compared to the frequency of modeled internal events having similar consequence. The total fire event frequency considers the event ignition frequency, severity factor and probability for hot short initiation (for example, a hot short that would cause inadvertent opening of a PORV causing a small LOCA event). A hot short probability of 0.1 was assigned in the Seabrook screening evaluation for important valves and components. An evaluation using a hot short probability of 0.6 was performed to assess the sensitivity of a change in hot short potential on the quantitative screening of fire events. Based on this evaluation, screening of fire events is relatively insensitive to a hot short probability in the range of 0.1 to 0.6. Although the 7 of 15

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure total frequency for each applicable fire event increases due to the increase in hot short potential, their contribution compared to the frequency of similarly modeled internal events is still relatively low.

For example, the frequency of a specific fire event in the East Main Steam Feedwater Pipe Chase resulting in an inadvertent ASDV opening contributes less than 20% of the modeled internal events frequency of steam line break which has the same plant impacts.

A total of 18 fire events were evaluated for sensitivity to the increase in hot short potential. The results of the sensitivity evaluation are summarized below. Based on the sensitivity evaluation, the increase in hot short potential is judged not to have a significant effect on the cost-benefit of other SAMAs.

Number of Contribution SAMA Disposition Fire to Modeled Events Internal That Events Include Hot Shorts 3 of 18 10% to 20% The 3 fire events that increase are related to inadvertent opening of an ASDV (steam line break). SAMA case NOSLB evaluated the benefit of complete elimination of steam line break contribution to risk. The result of this case are:

$3.1K (nom. benefit)

$6.OK (UB benefit)

OECR Red: -0%

Based on the conservative assessment, the benefit of complete elimination of SLB risk is very low. Therefore, no new SAMAs are identified relative to fire events and the increase in hot short potential is judged not to have a significant effect on the cost-benefit of other SAMAs. This result is not sensitive to the assumed increase in seismic risk evaluated in RAI 4.

15 of 18 <10% These events would continue to contribute only a small fraction (less than 10%) to the frequency of initiating events already modeled in the PRA. These initiators would not have a significant impact on the SAMA results. Therefore, the increase in hot short potential is judged not to have a significant effect on the cost-benefit of other SAMAs.

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United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure SAMA Supplemental RAI 2b Concerning the NextEra response to staff RAI 3.b:

b. Relative to the Fire-induced interfacing system loss-of-coolant accident (ISLOCA) &

Containment Impact section. For the "only area where isolation valves both inside and outside containment could be affected," clarify how "important isolation valves [that] could be controlled locally at the valve" would be so controlled for valves inside containment during operation. For the letdown system and its "several; fail closed air-operated valves (AOVs)," clarify the basis for the statement "it is not credible for all three valves to hot short." For "isolation failure of one or more valves of a single train," clarify the statement "the ability to remove power from fail closed valves to provide isolation" and the case for failed open valves due to hot shorting (which could not be de-powered?).

NextEra Energy Seabrook Response to SAMA Supplemental RAI 2b RAI regarding:

For the "only area where isolation valves both inside and outside containment could be affected, " clarify how "important isolation valves [that] could be controlled locally at the valve" would be so controlled for valves inside containment during operation.

Seabrook Response: Local control of valves applies to isolation valves located outside containment; these valves could be controlled locally or from the Remote Shutdown Panel. Valves located inside containment could be controlled at the Remote Shutdown Panel. No credit is taken for local control of valves inside containment.

RAI regarding:

For the letdown system andits "several;fail closed air-operatedvalves (A OVs),"

clarify the basisfor the statement "it is not credible for all three valves to hot short."

Seabrook Response: It is judged not credible for all of the letdown isolation valves to hot short and remain open for an extended time. Letdown isolation capability is provided by several redundant valves including one AOV outside containment and three AOVs inside containment. All four AOVs fail to the closed position upon loss of air or loss of control power. Shorts to ground of control cables for AOVs or SOVs will move the valve to its failed position just as loss of control power to the circuit. There are also two MOVs inside containment, which could be available for isolation.

RAI regarding:

For "isolationfailure of one or more valves of a single train," clarify the statement "the ability to remove power from fail closed valves to provide isolation" and the caseforfailed open valves due to hot shorting(which could not be de-powered?).

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United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure Seabrook Response: The assessment of fire-induced impact on containment isolation concluded that, for isolation failure of one or more valves of a single train, either redundant isolation would be available or the ability to remove power from fail closed valves to 'provideisolation is available. The ability to remove power from failed closed valves is based on the consideration that, for the subset of control power hot short events that maintain control power to the AOV/SOV, the AOV/SOV can be de-energized by removal of its divisional power supply. This is a reasonable consideration given the plant's divisional cable separation design. Thus, the overall conclusion reached in the review of fire-induced impact on containment is that the frequency of fires that could cause sufficient damage to fail containment isolation is low enough, compared to hardware failures, to not contribute significantly to loss of containment isolation.

SAMA Supplemental RAI 3 The response to RAI 3.c.a states that "[h]owever, the present PRA model has been updated to the more recent EPRI hazards," and that "[t]his was done because, while the methodology and experts used in developing the EPRI hazard are essentially the same as the Seabrook Station Probabilistic Safety Assessment (SSPSA), the EPRI hazard is more recent and the EPRI uniform hazard spectrum (UHS) developed for the Seabrook Station site is more realistic than that used in the SSPSA." Since the EPRI hazard curve was assessed in the individual plant examination external events (IPEEE) as a sensitivity case, and the SSPSA curves were considered the baseline, please clarify the basis for considering the SSPSA curves as the baseline and the EPRI curves as the sensitivity case, and why replacing the SSPSA hazard curves with the EPRI hazard curves is now more appropriate as the baseline representation for Seabrook Station.

NextEra Energy Seabrook Response to SAMA Supplemental RAI 3 As stated in the RAI 3.c.a response, the EPRI hazard is more recent than the original seismic hazard developed in 1983. In the 2005 PRA update, the more recent EPRI hazard and the related uniform hazard spectrum (UHS) developed for the Seabrook Station site were judged more realistic and representative of the best estimate hazard because of overall general improvement in seismic technology since the early 1980's. The more recent seismic hazard and UHS for Seabrook were developed in EPRI NP-6395-D, "Probabilistic Seismic Hazard Evaluations to Nuclear Plant Sites in the Central and Eastern United States: Resolution of the Charleston Earthquake Issue," April 1989.

SAMA Supplemental RAI 4 A seismic core damage frequency (CDF) of 2.2E-05 per year, based on the updated 2008 United States Geologic Survey (USGS) seismic hazard curves (as determined from GI- 199 information),

was used to develop a factor of 2.6 multiplier on the maximum attainable benefit (MAB). The potential effect of this factor is three-fold: (1) for those Phase II SAMAs that were previously screened on high cost or low benefit, the use of this factor could result in some of these SAMAs being reconsidered for a quantitative Phase II evaluation, (2) for those Phase II SAMAs previously evaluated quantitatively and dismissed as non-cost-beneficial, the use of this factor could now render some of these potentially cost-beneficial, and (3) for those Phase II SAMAs previously evaluated and 10 of 15

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure determined to be cost-beneficial, the use of this factor could increase the degree of cost-benefit. The revised MAB based on the 2.6 factor was used to re-assess only those Phase II SAMAs that were qualitatively screened based on high cost or low benefit (Item 1). Phase II SAMAs that were quantitatively evaluated in the original analysis were not re-assessed in the RAI response (items 2 and 3). Based on a scoping assessment by the NRC staff, applying the 2.6 multiplier to the estimated benefit for these non-re-assessed SAMAs will result in many SAMAs becoming potentially cost-beneficial, based on the current cost estimates. Please provide an assessment of the impact of the higher seismic CDF on all SAMAs, including those identified and evaluated in response to the staff's original RAIs. Note that this re-evaluation applies to all SAMAs, whether or not they result from internal or external event considerations. Specifically, please discuss whether random failures are included in the seismic analysis and, if not, use the 2.6 factor to assess the impact of the higher seismic CDF on the SAMA evaluation.

NextEra Energy Seabrook Response to SAMA Supplemental RAI 4 The Seabrook seismic risk analysis considers both seismic-induced component failures and non-seismic-induced component failures. Non-seismic-induced failures consider random, non-mechanistic, component failures, for example, pump fails to start and pump fails to run. These random component failures are assessed in seismic sequences where the seismic event's ground motion acceleration does not challenge the seismic capacity of the component.

In NextEra Energy's response to RAI 3g, Reference 3, a conservative multiplier of 2.6 was used to assess the possible increase in seismic CDF on the SAMA evaluation. The 2.6 multiplier was determined using the 2.2E-05/yr seismic CDF upper bound contribution as suggested by NRC using the earlier Seabrook IPEEE seismic results. The IPEEE seismic evaluation was submitted in 1992 before the Supplemental Emergency Power Supply (SEPS) was installed. Therefore the IPEEE risk results did not consider the seismic benefit of the SEPS. A more realistic multiplier of 2.1 is used, as documented below, based on crediting the seismic benefit of SEPS.

The Supplemental .Emergency Power System (SEPS) was installed at Seabrook Station in 2004. The SEPS diesels are a backup to the two emergency diesels. The SEPS automatically start on loss of offsite power and can be closed onto either emergency bus (E5 or E6, based on local alignment) from the main control room. If the emergency diesels failed (e.g., non-seismic failures) and a diesel could not be immediately recovered, plant operators would close the load breaker to align the SEPS to an emergency bus. SEPS is a seismically rugged component and has been evaluated by an independent consultant to have a median seismic fragility of 1.23g.

Credit for the SEPS function, including its seismic fragility, was modeled in the seismic PRA in 2005. Crediting SEPS in seismic sequences reduces the seismic CDF by approximately 26% by avoiding station blackout sequences. Applying this same factor to the IPEEE results, the IPEEE seismic CDF contribution when SEPS is credited can effectively be reduced by 26%, thus reducing the NRC suggested GI-199 seismic CDF contribution from 2.2E-05 to 1.6E-05. This seismic CDF contribution is used to refine the seismic multiplier used in RAI 3g from 2.6 to 2.1 based on the following approach:

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United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure Seabrook baseline CDF from (at power) internal and external events: 1.17E-05/yr (SSPSS-2009)

Seismic contribution to baseline CDF: 3.11 E-06/yr Estimated maximum seismic contribution from GI-199 (crediting the SEPS diesels):

2.2E-05/yr * (1.0 - 0.26) = 1.6E-05/yr Overall seismic increase factor:

(1.1 7E-05/yr - 3.11 E-06/yr + 1.6E-05/yr) / 1.1 7E-05/yr = 2.1 factor increase in CDF As the NRC staff indicated in this RAI, applying the multiplier to the estimated benefit for the non-re-assessed SAMAs would result in many SAMAs becoming potentially cost-beneficial based on the current cost estimates. As discussed in the ER, Reference 1, the SAMA phase II screening process was performed using a conservative approach to compare the SAMA potential benefit (conservative maximum benefit) against the SAMA potential cost (conservative minimum cost estimate).

As part of NextEra's response to this RAI, the assessment of the seismic risk multiplier impact on the SAMA evaluation included both a review of the PRA Case used to determine the SAMA benefit and a review of the SAMA's original cost estimate. This was done to understand conservatisms and to ensure that the SAMA risk benefit and cost estimate continue to reflect meaningful estimates.

Where NextEra judged the SAMA's original PRA Case to provide an overly conservative risk benefit, a more realistic, (but still conservative) PRA Case is used to provide the SAMA risk benefit.

Where NextEra judged the SAMA's original cost estimate to be overly conservative, the original cost estimate is revised to provide a more realistic (but still conservative) SAMA cost estimate based on an assessment of costs.

Table X-2 (Attachment A) provides the sensitivity evaluation of the potential seismic risk increase for SAMA candidates in Table F.8-1 of the Seabrook ER (Reference 1). Tables X-3 through X-8 (Attachment A) provides the sensitivity evaluation of the SAMA candidates that were evaluated in Seabrook's response to RAIs (Reference 3).

Changes to the SAMA cost estimate are provided in the Cost Estimate column of Tables X-2 thru X-8 with the change highlighted by strikethroughs for deleted cost and bolded italics for revised cost.

The basis for the change in cost is provided in the SAMA evaluation column. Any changes to the selected PRA Case are also shown similarly in Tables X-2 thru X-8, PRA Case column, and are also discussed in the SAMA evaluation column. Based on the assessment performed, the SAMA evaluation is insensitive to the assumed increase in seismic risk. As a result, no new SAMA candidates are identified as being potentially cost beneficial. It is also noted that SAMA cases using previous Cost Estimates would only have been justified by the extremely conservative "upper bound" benefit results. The upper bound benefit sensitivity is included only as a flag to consider more realistic costs and benefits, as was done above.

In addition to Tables X-2 through X-8, NextEra's response to RAI 51 (reference 3) is revised below based on the assumed increase in seismic risk:

12 of 15

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure When considering the seismic risk factor of 2.1, the maximum dollar benefit of a SAMA that eliminates 100% of the risk of a basic event having an RRW value of 1.005 is approximately $5.25K (nominal benefit at 7% discount rate) and approximately $10.1K (upper bound benefit).

SAMA Supplemental RAI 5 The response to staff's RAI 5.b states that all top ranked basic events related to large early release frequency (LERF) have been addressed in response to RAI 2.f. This appears to be the case with the exception of basic event FWP 161 .FS, which has a LERF risk reduction worth (RRW) of 1.0886 (see Environmental Report Table F.3.2.1-2). Please provide an assessment of this basic event for SAMAs, including an identification of the specific basic events that bound this basic event and the associated SAMAs.

NextEra Energy Seabrook Response to SAMA Supplemental RAI 5 Basic event FWP 161 .FS models failure to start of the Pre-lube Oil Pump (FW-P-161). Operation of this pump is needed for success of the Startup Feedwater Pump (FW-P- 113). The potential SAMA candidate would be to improve the reliability of the pre-lube pump via installation of a redundant pump. PRA Case SUFPS is used to conservatively estimate the SAMA benefit. This case is conservative because it assumes guaranteed success of the entire Startup Feedwater system. Basic event FW-P-161 contributes approximately 17.5% to the unreliability of the SUFP system.

Therefore, the maximum benefit associated with reliability improvements to the pre-lube pump is approximately 17.5% of the SUFPS PRA case results.

FW-P- 161 benefit results 7.4K (nominal benefit)

$14.2K (UB benefit)

OECR Red: <1%

Min. Cost: >100K

==

Conclusion:==

Not cost beneficial based on assumed guaranteed success of the pre-lube oil pump and estimated cost. This cost benefit result is not sensitive to the assumed increase in seismic risk evaluated in RAI 4.

SAMA Supplemental RAI 6 The response to staffs RAI 5.b provides the same disposition (not beneficial based on eliminating all supplemental electric power system (SEPS) failures), same associated SAMAs (#9 and #14), and same two pairs of case studies (PRA cases SEPS for #s 8-9 and OSEPI for#s 10-11) for basic events

8, #9, #10, and #11, yet the estimated benefits are different between the pairs #s 8-9 and #s 10-11.

Clarify the differences in the treatment of these four SAMAs, including the two different case studies and provide additional details on the modeling assumptions for each.

13 of 15

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure NextEra Energy Seabrook Response to SAMA Supplemental RAI 6 Basic events SEPSDG2A.FR3 and SEPSDG2B.FR3 (items #8 and #9) model the fail-to-run failure mode of the supplemental electric power supply (SEPS) diesel generators A/B. PRA case SEPES is used to estimate the potential benefit of improving SEPS reliability (e.g. add an additional SEPS diesel). The SEPES PRA case assumes guaranteed success of all SEPS DG hardware (successful start and run). Manual actions to align and connect SEPS to the desired electrical bus are assumed to remain at their baseline HEP values. The SAMA disposition for these basic events is not cost beneficial based on assumed elimination of all SEPS hardware failures which, even with an additional DG, is not practical to achieve. As provided in SAMA#189 of Reference 1, the estimated cost of modifying or analyzing SEPS DG success criteria capability such that 1 of 2 SEPS DGs has capacity to provide LOSP non-SI loads and 2 of 2 SEPS DGs have capacity to provide LOSP SI loads exceeds $300K.

It is noted that the basic event description for item #11, HH.OHPR3.FA, was incorrect in RAI 5.b; this operator action is not related to SEPS. A SAMA evaluation for HH.OHPR3.FA is provided in Table X- 7.

Basic event HH.OSEP 1.FA (item #10) models the human action to manually close the SEPS breaker without a safety injection signal. The action to manually close the SEPS breaker is required to connect SEPS to the desired emergency bus. PRA case OSEPI assumes guaranteed success of operator action OSEP 1 and is used to estimate the potential benefit of improving the reliability of connecting SEPS to the desired bus (e.g. add a SEPS automatic start and load feature). In this case, the SEPS hardware is assumed to remain at its baseline failure probability. The SAMA disposition in the RAI 5.b table of top 15 RRW basic events stated; not cost beneficial based on assumed elimination of all SEPS failures. This was a carry-over from earlier SEPS basic events and is not accurate for the OSEPI case. The more correct disposition for basic event OSEPI is; not cost beneficial based on assumed elimination of the OSEPI action. It is noted that an additional PRA case related to human action HH.OSEP2Q.FA (Case OSEPALL) is provided in NextEra response to RAI 2.f. This case modeled elimination of all manual actions associated with SEPS. The SAMA disposition for providing automatic control of the SEPS breaker is not cost beneficial. As provided in SAMA#154 of Reference 1, the estimated cost to modify the SEPS design to accommodate automatic bus loading and alignment is >$750K.

SAMA Supplemental RAI 7 Clarify why NextEra believes the uncertainty distribution represents the uncertainty in the fire and seismic portions of the PRA model. Include a discussion of whether probability distributions were assigned for external events (such as for fire ignition frequencies, non-suppression probabilities, hot short probabilities, seismic frequencies, other seismic parameters) and, if not or only done so partially, how this impacts the SAMA analysis, including any specific examples of where probability distributions were applied in the fire and seismic models.

14 of 15

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure NextEra Energy Seabrook Response to SAMA Supplemental RAI 7 The NextEra Seabrook PRA fire and seismic results consider uncertainty. Specifically, uncertainty is considered for fire initiating events, seismic initiating events, component seismic fragilities, operator actions and component non-seismic/random failures. Hot short probabilities are accounted for in the fire events screening evaluation, which does not apply uncertainties. Uncertainties in non-suppression probabilities were not specifically addressed in the quantification. However, non-suppression uncertainty is addressed in fire events sensitivity evaluations. A number of sensitivity evaluations were performed to support the fire events and seismic events models to ensure the reasonableness of the key inputs. The results of the sensitivity studies indicate that the baseline fire and seismic results are relatively insensitive to reasonable variations in key inputs. Based on the level of uncertainty applied in the fire events and seismic events analyses, and the associated sensitivity studies performed, the calculated model uncertainty distribution adequately reflects the uncertainty for both internal and external events and is judged reasonable for the SAMA evaluation.

SAMA Supplemental RAI 8 In the response to RAI 5.f for Essential Switchgear Rooms, clarify if electrical raceway fire barriers are also considered for fire areas where cables for redundant trains may be co-located.

NextEra Energy Seabrook Response to SAMA Supplemental RAI 8 As discussed in the response to RAI 5.f, the switchgear rooms are safety train separated. The review of fire impact scenarios on the individual switchgear room components and cables performed as part of the fire risk analysis, did not identify redundant safety train cables/impacts. The switchgear room scenarios involve fires in a single switchgear room/division, with subsequent fire-independent hardware failures of redundant components. Therefore, additional fire barriers were not considered.

15 of 15

United States Nuclear Regulatory Commnission SBK-L-1 1067 / Enclosure /Attachnment A Attachment A to SBK-L-11067 Tables X-2 through X-8 NextEra Energy Seabrook Responses to Supplementary NRC Request for Additional Information Regarding Severe Accident Mitigation Alternatives Analysis 1 of 55

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure /Attachment A rable X-2 , Seabrook Station Sensitiiy Evaluation-using.Seismic:skMultiplier of2.11.

-:.C:' i # rmSar~2Ei dates ar.e.;*:.::.?* : ibe*i2**i

ii::i?!{i Tablei*: !s': *:* }:¢i i!:ii':"?:.;ii:::*k:~£ in:.S:abr%:-E F.8-1)-ii.:i",,:!:

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.: *: !:i;:i:::

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Potetia NJominal~:Pe i SAMA%ý. n Discussion, PRA Case Denefit at df Bnitt Etmt Evaluation Nmb mJlproVemnift t af stiat Replace lead-acid Extended DC powe Not cost beneficial. PRA case NOSBO conservatively assumes elimination of all station blackout 2 batteries with fuel availability during NOSBO $326K $629K >Sim events. The cost of replacing, battenies is expected to significantly exceed benefit.

cells; an SBO Not cost beneficial. PRA case NOLOSP conservatively assumes elimination of all LOSP events.

Install an Cost of installing buried, alternate power source expected to significantly exceed benefit.

additional, buried Reduced probability 4S24M Reduction in seismic risk not significant unless offsite power source is seismically rugged.

1 of-iepo.wer pofe loso ffst OOS 74 $.4 This improvement was previously estimated at $2.485M dollars in the Cooper License Renewal sourcipwe application. Estimate far exceeds the upper bound benefit of $1.34M, and no more refined estimate is warranted.

Not cost beneficial. PRA case NOSBO conservatively assumes elimination of all station blackout events by assumning guaranteed success of onsite diesel generators. Cost of installing an alternate a gas IcesdNOSBO power gas turbine expected to significantly exceed benefit Reduction in seismic risk not 14 Install triegnrtr availability of on- PW 326K $620K $>lM significant unless gas turbine is seismically rugged. PRA case NOSBO is judged more 14 tr~re gnertor site AC power representative than original PRA case NOLOSP. This is because the gas turbine would not eliminate the LOSP event, but rather would help avoid station black-out subsequent to the LOSP event.

Not cost beneficial. PRA case NOSBO conservatively assumes elimination of all station black-out Increased events by assuming guaranteed success of onsite diesel generators. Cost of installing additional Improve aviaiiyopwr NSOpower supplies expected to significantly exceed benefit Reduction in seismic risk not sign.ificant 16 uninterruptible avulablies ofppowrtn AWSB $326K S620K >SIM unless power supplies are seismically rugged. PRA case NOSBO judged more representative power supplies supptlines squipportin than origintal PRA case NOLOSP. This is because additional uninterruptible power supplies frontlineequimentwould not eliminate the LOSP event, but rather would help avoid station black-out subsequent to the LOSP event Add diselNot ne Inceasd cost beneficial. PRA case NOSBO conservatively assumes elimination of all station blackout 20 Iback-up source of generator NOSBO $326K S629K >SIM events. The cost of installing back-up cooling source is expected to significantly exceed benefit o_________

diesel cooling availability Intent of this SAMA is met and furfther development is not cost beneficial. Detailed procedures Incrasedexist for inspection and repair of 4k-V breakers. These procedures are applied to both safety probability of related and non-safety related breakers to ensure that these breakers are proper maintained and Develop recovery from highly reliable. The PRA case BREAKER conservatively assumes guaranteed success of all 4kV procedures to failure of breakers safety and non-safety bus feeder breakers. Thus, the benefit of iniplernenting additional 21 repair or replace that transfer 4.16 W BREAKER $17K $32K -measures for repair and replacement of non-safety breakers is conservatively high. Given that Ifailed 4 KV non-emergency inspection and repair procedures exist, no further actions are judged needed for this SAMA.

breakers buses from unitRePrcdes station service transformers LS0558.04. 4.16KV Circuit Breaker Refurbishment

________I I_______ I________ I____ I____ LX0558.01, 4.16KV Breaker Inspection, I________ esting, and PM 2 of 55

United States Nuclear Regulatory Commission SBK-L- 11067/ Enclosure /Attachment A r*bs*ioo :-f . Statin R of!

Table :-"::*:y da :ikMultiplier

'ar~om bsi

Eauto sn

~SAM~anidaes~arefrm'arook ER-Table F.8-1) -L~ '-::*-:::........................:.............*.*.-..:.:.*.*.....................'........*.*...*."........

........

Salli Nom:in Upperc s. :.:..:.::;: -. :

... Discussio Co"st:..'

BP*A*o:u.n-.ee*itat Evaluation NubW Nuniber

IinRrvemeit nl"Ovnn at i' Benefit at EstimteI

. _.._*::*. __......,.. .:..-____ .x ...............

Not cost beneficial. PRA case NOLOSP conservatively assumes elimination of all loss of offsite Buray off-site Imroedof-ste>$3M expecte to significantly power events. exceedpower Burying offsite benefit lines to the station is judged not practical and cost is power reliability NOLOSP S704K $1.34M 24 Bury off-site power lines during sever $ This improvement was previously estimated at SI .14B dollars in tle Cooper License Renewal weather application. Estimate far exceeds the upper bound benefit of $1.34M, and no more refined estimate is warranted.

Not cost beneficial. PRA case LOCA02 conservatively assumes guarantced success of all high SI pumps.) Therefore, the benefit of head and intermediate head injection pumps (charging and installing a single, independent backup injection system is judged conservatively high.

Installation of an independent, active or passive injection system is judged not practical and cost Install an is expected to significantly exceed the conservative benefit Given the seismic ruggedness of the independent Improved >S2M existing injection system(s), any new/additional system would need to be equally rugged to 25 active or passive prevention of core LOCA02 $978K $I.9M significantly reduce plant risk. Including seismic ruggedness in the design would further increase high pressure melt sequences cost.

injection system This improvement was previously estimated at greater than $2 million dollars in the Pilgrim License Renewal application. In the Duane Arnold License Renewal application, the Pilgrim estimate was judged to be low and used a $20 million estimate based on similar modification experience. Both estimates exceed the upper bound benefit of $1.9M, and no more refined estimate is warranted.

Not cost beneficial. PRA case LOCA02 conservatively assumes guaranteed success of all high head and intermediate head injection pumps (charging and SI pumps.) Therefore, the benefit of installing a single, independent, backup injection system is conservatively high. Installation of an Provide an additional injection system is judged not practical and cost is expected to significantly exceed the additional high Reduced frequency conservafive benefit. Given the seismic ruggedness of the existing injection system, any 6pressure injection ofore melt from 9>$2M now/additional system would need to be equally rugged to significantly reduce plant risk.

pump with small LOCA and LOCA02 $978K $1.9M Including seismic ruggedness in the design would further increase cost independent SBO sequences This modification was assumed to be the equivalent of adding one new high pressure injection diesel pump powered by a diesel rather than an electric motor with a suitable injection path and suction source. In the Duane Arnold Lioense Renewal application, the cost of this was one half the cost of replacing pumps discussed in SAMA25 above, the cost would be $10 million. This estimate far exceeds the upper bound benefit of$1.9M and no more refined cost estimate is warranted.

Add diverse low Not cost beneficial. PRA case LOCA03 conservatively assumes elimination all low pressure 2 p i Improve injection 28 sste capability LOCA03 S336K $639M >SIM injection failures. The cog of installing an additional low pressure injection system is expected Ssystem cto significantly exceed benefit 3 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A rableX-2 ~ea;S:6bro-ok.S6tion Sen'sitv*i*tyEvluatio6n using Sels6ic Mik'Multiplie'rof2.1 - :

'SAMA'Candidates arOmScbol'R blF84I Nomiinal Upper

.. .- Discussion i o:P.et- PRA Case Benefit at . o. Evaluation.[.I o : .on. .. . .

Imorovement Benefit at Estimate, Not cost beneficial. PRA case LOCA04 conservatively assumes gnaranteed success ofthe RWST volume as a continuous source of water for ECCS. Therefore, the benefit ofthrottling low pressure injection to extend the time to RWST depletion for medium or large break LOCA events is conservatively high. The current system valves and controls do not allow throttling. The cost of engineering analysis, installation ofthe proper valves, control systems, etc. to accomplish this SAMA Throttle low is expected to significantly exceed the conservative benefit Given the seismic ruggedness of the pressure injection exsting injection system, any system changes would need to be equally rugged so as to not impact pumps earlier medums in earliMer- Exthe Extended reactor >$1M cost.current seismic design basis. Including seismic ruggedness in the design would further increase 35 medium or large- water storage tank LOCA04 $332K $630K 4500 break LOCAs to> capacity maintain reactor Implementation would require both LOCA and Containment Mass Energy calculations to be water storage performed. Additional analysis would be required to verify ECCS flow balance and NPSH for low, tank inventory intermediate and high head SI pumps. The implementing modification would address design and licensing basis changes as well as post mod testing to validate required flow balance is achieved.

Pending review of the throttling capability of existing system valves, hardware changes may be necessary to achieve the desired results. The expected cost to implement SAMA 35 will exceed the upper bound benefit of $630K.

Not cost beneficial. PRA case LOCA02 conservatively assumes guaranteed success of all high head and intermediate head injection pumps (charging and SI pumps.) Therefore, the benefit of replacing two electric motor pumps with diesel-driven pumps is conservatively high. Installation Reduced common of diesel-driven pumps in place of the existing motor-driven pumps is judged not practical and Replace two of cause failure of the cost is expected to significantly exceed the conservative benefit. Given the seismic ruggedness of the four electric safety injection the existing injection system, any new/additional equipment would need to be equally rugged so safety injection system. The intent >$2M as to not impact the current seismic design basis. Including seismic ruggedness in the design 39 pumps with of this SAMA prvie ivrst is to LOCA02 $978K $1.9M would further increase cost.

diesel-powered provide diversity Changes to how safety related pumps are powered would require substantial changes to the foot within the high- and pumps low-pressure safety print of the system and re-analysis of safety related piping in addition to the procurement and injections systems installation of the diesel power device. Due to complexity of this modification, the Duane Arnold License Renewal application estimates the cost to be similar in nature to replacement of pumps mentioned in SAMA 25 above ($20 million). As this value substantially exceeds the upper bound benefit of $S.9M, no more refined estimate is warranted.

4 of 55

United States Nuclear Regulatory Commission SBK-L-l 1067 / Enclosure /Attachment A rable X-2 , 'Seabrook Station Sensitivity Evaluation using Seismic Risk Multiplier of 2I.t SAMAoCandidates are from;Seabrook ER Table F.8-1) , .,

s~irolkNominal' pe

.. t.ntil .Discussion. PRA Case , Benefit at Bou.d.at Co...Evaluation....... .......

Improvement Benefit Ettimate Allows low pressure emergency core Create a reactor co l n syste 41 coolant depress coling the LOCA01 $70K $132K >$IM Not cost beneficial. PRA case LOCAOI conservatively assumes elimination small LOCA events.

event of small The cost of installing an RCS depressurization system is expected to significantly exceed benefit system LOCA and high-pressure safety injection failure Add redundant Increased >$100K Not cost beneficial. PRA case SWOI conservatively assumes that the SW pumps are not 43 DC control power SWO1 $20.6K S40K dependent on DC power. The cost of installing an independent DC power system for the SW for SW pumps availability ofSW pumps is expected to significantly exceed benefit Not cost beneficial PRA case CCWOl conservatively assumes guaranteed success of the component cooling water (CCW) systems to provide heat removal. Because CCW is needed for success ofthe ECCS divisions (including room cooling), the benefit of installing ECCS pump motors that are independent of CCW is conservatively high. Installation of air cooled pumps would still rely on room cooling/COW. Therefore, this SAMA would provide negligible benefit and its cost for replacing eight large motors would be expected to significantly exceed even the Replace ECCS Elimination of conservative benefit Given the seismic ruggedness of the existing injection system, any new pump)motors EGGS dependency >s4M equipment would need to be equally rugged so as to not impact the current seismic design basis.

44. ith aoole with air-cooled on component on coponent CCWO0 $384K $731K >5$500K4 Including seismic ruggedness in the design would further increase cost motors cooling system Since all ECCS pumps are dependant on component cooling, the cost ofthis improvement was assumed to be the cost of eight large safety related pumps, engineering design support and installation for a total of at least S4 million. Similar to SAMA 170, replacement of a single large safety related pump independent of cooling water is estimated to cost in excess of $500K. No allowance in the cost estimate was given to account for the possibility that complex support or fit changes were needed. As this value substantially exceeds the upper bound benefit of $731K, no more refined estimate is warranted.

Install an Reduced frequency independent of core damage reactor coolant Not cost beneficial. PRA case RCPLOCA conservatively assumes that RCP seal LOCA events 55 pump seal from loss of RCPLOCA $173K $370K >$IM are eliminated. The cost of installing an independent seal injection system with or without a component cooling injection system, water sece *er dedicated diesel is expected to significantly exceed benefit.

with dedicated diesel or station blackout Install an Reduced frequency independent of core damage reactor coolant from loss of Not cost beneficial. PRA case RCPLOCA conservatively assumes that RCP seal LOCA events 56 pump seal component cooling RCPLOCA $173K $370K >$3M are eliminated. The cost of installing an independent seal injection system with or without a injection system, water or service dedicated diesel is expected to significantly exceed benefit.

without dedicated water, but not a diesel station blackout 5 of 55

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure /Attachment A

ý .. . .. . . ... .. I 1........ .. .... _ .. .... ... .

SAA andid ates are from SeabrookI _____ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Seabrook :~ ni~I I Nominal, pprI' Amkprot eentia Discussion PRJ& Case: Benefit at) ~ f 1 Eoid valuation ,I Not cost beneficial. PRA case CCWOl conservatively assumes guaranteed success of the component cooling water (CCW) systems to provide heat removal. T1hus, the benefit of installing an additional CCW pump is conservatively high. Seabrook has four COW pumps. Adding an additional pump wIll not significantly reduce plant risk due to common-cause failure Redcedliklihodconsiderations and limitations in divisional power. installaton of an additional pump would still Install an Redcel ioesiof rely on the same power supplies as the existing pumps. The cost of installing an additional COW additional cofmlossn cOfl >SIM pump isexpected to significantly exceed the conservative benefit. Given the seismic ruggedness copoen coolingn CCWOI $384K $731K of the existing injection system, any new equipment would need to be equally rugged so as to not 59 comolngaent water leading to a ~4$0K impact the current seismic design basis. Including seismic ruggedness in the design would reactor coolant further increase cost. It is also noted that Seabrook-has an alternate cooling configuration for the pumpsealLOCAcharging pumps should there be a loss of COW. This altemnate cooling configuration reduces the likelihood of loss of RCP seal injection/cooling and associated seal LOCA sequences.

This improvement was previously estimated at greater than $1.2 million dollars in the Kewaunee License Renewal application. As this value substantially exceeds the upper hound benefit of

$73 1K. no more refined estimate is warranted.

Install a digital loduce chanc ofee Not cost beneficial based on an upper bound maximumn attainable benefit (MAB) of SI.56M '

65 feed water loss ofolmain feed >$30M 2.1 = $3.3M. The cost of installing the digital feedwater control upgrade is expected to upgrade Plant trip significantly exceed benefit.

Provide a passive. Reduced potential Not cost beneficial based on an upper bound maximum. attainable benefit (MAB) of $1.56M*

secondary-side fo core damage due 2.1 = $3.3M. As stated in Reference 3, RAI response 3g the installation of such a system is 77 heat-rejection - - >SIOM loop consisting of to loss-of-feedwater judged not practical at an existing nuclear power plant such as Seabrook Station. The cost of this acnesrad events SAMA would be in excess of SlOM significantly exceeding the MAB benefit heat sink__ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Replace existing This SAMAA is firom Reference 3, RAI 5g and is evaluated for sensitivity to the 2. lx. risk increase.

pilot-operated 0Not cost beneficial. PRA case FWOI coonservatively assumes elimination of loss of feedwater relief valves with Increased events. The cost of replacing, the PORVs to increase capacity and improve feed and bleed lagroe7sch poa9iyo FWOI $154K $294K performance is expected to significantly exceed benefit.

that only one is successful feed and MQ required for bleed This SAMA was previously estimated at $237M in the Calvert Cliffs Ucense Renewal application successful] fee (SAMA 77). Estimnate far exceeds the upper bound benefit of $294K and no more refined and bleed estimate is warranted.

aIncreased Provde Provinden taino availability of Not cost beneficial. PRA case HVAC2 conservatively assumes no HVAC dependency for CS, 80 means of components HVAC2 $67.2K $128K >5500K SL RH-Rand CBS pumps. The cost of installing aredundant or independent HVAC system is ventilation dependent on room expected to significantly exceed benefit

__________ cooling____ __ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

6 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A Table X-2 Sabrook Se: StationSensitii'ty Evaluation iusing Seismic Risk Mul4iplier of2.. it . ;

' "."A* L , : . .: . . '. * . . : :. '- . . F" S-.l) ' . " " "* . , * " "I:" : :. ' i : " . : " ' : : : :.* : '! .* :! * .!'. . *[ " * : :![. '. " EI* : q : ?; ' * "* * ' 'r ' L : ' ' * :

(SAMA Candidates are from Seabrook ER'Table F.8-1

"~ ~~.. :!~ '*: ~ ~"::'":"'. ~ ~~~~~~~. '!*"::":"" ... .......

" .... ................ .".*...'*

.*

liil upper ' '

Sote4ti Rounid Cost Evutin111 SAMAo NImprovement Discussion .kefit PRACase ait Benefitjt Estimate Evauaion

.'" -[ - . .

Create ability to switch This SAMA isfrom Reference 3, RAI 5g and isevaluated for sensitivity to the 2.lx risk increase.

emergency Continued fan Not cost beneficial. PRA case OEFWVS conservatively assumes no HVAC dependency for 84 feedwater room operation in a OEFWVS <SlK <$2K >$250K EFW pumps. The cost of modifying the HYAC system to allow for DC power supplies is fan power supply station blackout expected to significantly exceed benefit to station batteries in a station blackout Enhanced debris Create a reactor cool ability, reduced Not cost beneficial based on an upper bound maximum attainable benefit (MAB) of $1.56M

90 cavity flooding core concrete >$4M II = $3.3M. As stated in Reference 3, RAI response 3g. the installation of a cavity flooding 0caty interaction, and system is judged not practical at an existing nuclear power plant such as Seabrook Station. The increased fission cost of installing a reactor cavity flooding system is expected to significantiy exceed benefit product scrubbing Not cost beneficial. PRA case CONTOI conservatively assumes the containment does not fail Install a passive Improved due to overpressure. As stated in Reference 3, RAI response 3g, the installation of a passive 91 containment containment spray CONT01 $342K $651K >$6M containment spray system is judged not practical at Seabrook Station. Design and spray system capability implementation costs are judged to realistically exceed $3M to $6M The cost of installing a passive containment spray system is expected to significantly exceed benefit.

Increased decay heat Install an removal capability Not cost beneficial. PRA case CONTOI conservatively assumes the containment does not fail 93 unfiltered, for non-ATWS CONT01 $342K $651K >$3M due to overpressure. As stated in Reference 3, RAI response 3g, the cost of installing a unfiltered containment vent scrubbinnrelewed hardened containment vent system is expected to significantly exceed benefit.

fission products Install a filtered Not cost beneficial. The conservative PRA case CONTOI assumes elimination of containment containment vent removal capability failure events due to overpressure. The context of this SAMA is to eliminate containment to remove decay overpressure failure events by removing decay heat from containment via a filtered vent which heat Option 1: for non-ATWS >$5M would retain fission products. Based on the high level concept for this SAMA, installation of a 94 Gravel Bed events, with CONT01 $342K $65 1K >5Q filtered vent system is expected to be in the range of $SM to $6M.

Filter2Option 2: scrubbing of Multe Opti released fission This SAMA was previously estimated at $5.7M in the Calvert Cliffs License Renewal application Multiple Ven products (SAMA 12). Estimate far exceeds the upper bound benefit of $651K and no more refined Scrubber estimate is warranted.

Provide post-96 accident containment Redued of hydrogen likelihood and Not cost beneficial. PRA case H2BURN conservatively assumes that hydrogen bums and inerting carbon monoxide H2BURN <$1K <$IK >$100K detonations do not occur. The cost of installing a containment inerting system is expected to inerting csignificantly exceed benefit.

capability gas combustion 7 of 55

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure /Attachment A rable~iX-2, tie* Sbook Station n* S"e:ab . o"k'tSestit ro E R:'.:.

ATi6:M. .Evaluatioii

. . using Seism'ic.

. ,,'a.: Riisk Mtultiplier

2 , .id'a = " "a 21 o6f : .., II

': " '" ::::" ' " - i " :: ;1); I ": i* i ; ; -I i :

I1j: I k Caw Benefin at - pe, . . : vlainI a o.:Discussion .- I::. :.

Improvement ~abro1 Beneefitt at Eound Co t t I

.umb.. 2.h1:... Vx-.

Increased cooling and containment of molten core debris.

Molten core debris Create a large escaping from the concrete crucible vessel is contained Not cost beneficial based on an upper bound maximum attainable benefit (MAB) of S1.56M with heat removal within the crucible >$5OM 2.1 = S33M. As stated in Reference 3. RAI response 3g the cost of installing a core catcher and potential to and a water cooling cooling system in the reactor cavity is expected to significantly exceed benefit and is not practical contain molten mechanism cools at Seabrook Station.

core debris the molten core in the crucible, preventing melt-through of the base mat Increased cooling and containment of molten core debris.

Refractory material would be placed underneath the reactor vessel such that a molten core Not cost beneficial based on an upper bound maximum attainable benefit (MAB) of $1.56M

Create a core falling on the 2.1 = $3.3M. As stated in Reference 3, RAI response 3g. the cost of installing refractory material "98 melt source reductionurcet m material ateria would w ith melt >$50M in the reactor cavity is expected to significantly exceed benefit and is not practical at Seabrook rdcinsystem and combine with Station.

the material.

Subsequent spreading and heat removal from the vitrified compound would be facilitated, and concrete attack would not occur Strengthen Not cost beneficial. The conservative PRA case CONTO0 assumes elimination of containment primary/secondar Reduced probability failure events due to overpressure. The context of this SAMA is to eliminate containment 99 y containment of containment over- CONTOI $342K $651K >$1OM overpressure failure events by adding reinforcement to containment. As stated in Reference 3.

add ribbing (e.g., tpressurization pressurization RAI response 3g., based on the high level concept for this SAMA. installation of reinforcement to containment steel is expected to significantly exceed the benefit.

shells)l)_________ _____ ___________ ____I___________I__________I___________I____

8 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A Table X-2 e--

abrook SttionSensitivityEvaluationlpn g SismicRsk li erfA :si 0 (SAMA.CandidatesarefromSeabrookER TaF--- -. i: . - , ; -

S~abookDisusson ~Upp-er Number eme SAAEssita Dmpro, PRACase Benefitat uvaluation Benefit at -stimate . .

-

Increase depth of the concrete base Not cost beneficial based on an upper bound maximum attainable benefit (MAB) of $1.56M

mat or use an Reduced probability 2.1 = $33M. As stated in Reference 3, RAI response 3g- the cost of installing additional base 100 alternate concrete ofbase mat melt- >$5M material to ensure through mat concrete material in the reactor cavity is expected to significantly exceed benefit and is not melt-through practical at Seabrook Station does not occur Not cost beneficial based on an upper bound maximum attainable benefit (MAB) of S1.56M

Increased potential 2.1 = $3 3M. The cost of installing an RPV external cooling system is expected to significantly to cool a molten exceed benefit and is not practical at Seabrook Station. As stated in Reference 3, RAI response 101 v exterior vessel icore crbeoeicass>$5M before it causes 3g Seabrook Station currently has several proceduralized methods to ensure that the reactor vessel failure, by cavity can be flooded to provide a means of external vessel cooling. These methods include submerging the containment injection ofthe RWST contents and containment injection via the fire protection lower head in water system through an ILRT flange (refer to SAMA #188). Therefore, it is judged that the current Seabrook Station design meets the intent of SAMA #101.

Construct a building to be Not cost beneficial. The conservative PRA case CONTO1 assumes elimination of containment connected to Reduced probability failure events due to overpressure. The context ofthis SAMA is to eliminate containment 102 primary/sec, of containment over- CONTO1 $342K $651K >$1OM overpressure failure events by adding a system to evacuate containment As stated in Reference containment and pressurization 3, RAI response 3g. based on the concept of this SAMA, installation of a containment evacuation maintained at a building/system is expected to significantly exceed the benefit vacuum Delay This SAMA is from Reference 3, RAI Sn and is evaluated for sensitivity to the 2. Ix risk increase.

containment Extended reactor Not cost beneficial. PRA Case OLPRS conservatively assumed guaranteed success of the 105 spray actuation water storage tank' OURS $15. I K $29K >$10K operator action to complete/ensure the RHRILHSI transfer to long term recirculation during large sayatiter alagitak storrge RLOCA events. The results of this case study show that the operator action does not contribute after a large availability significantly to core damage frequency. The estimated cost is expected to significantly exceed benefit Not cost beneficial. PRA case LOCA04 conservatively assumes guaranteed success of the RWST volume as a continuous source of water for ECCS. Therefore, the benefit of throttling containment spray flow to extend the time to RWST depletion is conservatively high. The cost of Extended time over engineering analysis, installation of the proper valves, control systems, etc. to accomplish this Install automatic which water remains SAMA is expected to significantly exceed the conservative benefit containment in the reactor water >SIM Implementation would require both LOCA and Containment Mass Energy calculations to be 106 spray pump storage tank, when LOCA04 $332K $630K performed. Additional analysis would be required to verif ECCS flow balance and NPSH for low.

header throttle full containment 4 intermediate and high head SI pumps. The implementing modification would address design and valves spray flow is not licensing basis changes as well as post mod testing to validate required flow balance is achieved.

needed Pending review of the throttling capability of existing system valves, hardware changes may be necessary to achieve the desired results. The expected cost to implement SAMA 35 will exceed the upper bound benefit of $630K.

9 of 55

United States Nuclear Regulatory Commission SBK-L-11067 / Enclosure /Attachment A rable Xi-z2

. . . : :. . . Seabrook Station . Sensitiviy . . Evaluation

.I.. .

usingoSeism

. . . .

Risk Multiplier

. . .. .

of 2.1

.. . . , . . . . . - .: . .1 . .. ' . "1*: ' ' . : . : .1" .. : .

.. .. .5.. . .r ..f . . . a ~ . .. n. . ... ~

T_,:. ..:.. . : * . . . . . I.. . . .. . . . :. . . , . . . . . . . . . . . .. ,

............. *......

... ,,........... *................. .... ,

Jub.............,

.*d_*

i i mproteent .................

'..............".....:.::.......

Potential:<~Boun Estimate Benefit.at :J:. Cost -*...Ealtin* *............

1V Not cost beneficial. The conservative PRA case CONTOI assumes elimination of containment redundant Increased failure events due to overpressure. The context ofthis SAMA is to eliminate containment 107 containment containment heat CONTO0 $342K $651K >$4M overpressure failure events by adding a redundant containment spray system. As stated in removal ability Reference 3, RAI response 3g- based on the high level concept for this SAMA. installation of a spray system containment spray system is expected to significantly exceed the benefit Install an independent power supply to the hydrogen control system using either new batteries, a non-safety grade Not cost beneficial. PRA case H2BURN conservatively assumes that hydrogen bums and 108 portable Reduced hydrogen H2BURN <$1K <$1K >$100K detonations do not occur. The cost of installing an independent power supply to the H-12 control generator, detonation potential system is expected to significantly exceed benefit It is noted that SAMA # 108 would benefit existing station from SAMA # 157, portable AC generator, which was shown to be potentially cost beneficial batteries, or existing ACIDC independent power supplies, such as the security system diesel Install a passive Reduced hydrogen Not cost beneficial. PRA case H2BURN conservatively assumes that hydrogen burns and 109 hydrogen control Rn H2BURN <41K <$1K >$IOOK detonations do not occur. The cost of installing a passive hydrogen control system is expected to system detonation potential significantly exceed benefit.

Erect a barrier that would provide enhanced protection of the Not cost beneficial based on an upper bound maximum attainable benefit (MAB) of $1.56M

containment Reduced probability 2.1 = $33M. As stated in Reference 3. RAI response 3g. the cost of installing additional 110 walls (shell) from of containment >$5M ejected core failure concrete barrier material in the reactor cavity is expected to significantly exceed benefit and is not debris following practical at Seabrook Station.

a core melt scenario at high pressure 10 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A Table X-2 '.:Seabrook Stationi Sensitivi'E'vluation using Seism ic Risk Multiplier of2.1- :'.: :. .

(SAMAkCaindidates arefrom Seabrook:ER*Table F.8'1)

BNominialt,

,Upper iii,'

Seabrook'. Benefit ati: Bound cost Potential' Dis-cussion PRA Case Evaluation. I SAMAk-i' imiprovement JBenefit at ill,!

Number-Not cost beneficial. PRA case CONT02 conservatively assumes guaranteed be success of all containment isolation valves. At Seabrook containment isolation valves are already equipped Add redundant Reduced frequency with limit switches. The limit switch function is primarily for valve position and diverse limit of containment indication/verification and judged not to contribute significantly to the overall reliability of the 112 switches to each isolation faure and containment isolation valves themselves. Adding an additional limit switch would not provide containment significant improvement in the reliability ofthe isolation function. For SAMA purposes, the limit 5

isolation valve switches are conservatively assumed to contribute 0% to the containment isolation function.

Thus, the PRA case upper bound benefit is less than $834K

0.5 = 5417K and is judged not cost beneficial.

Not cost beneficial. PRA case LOCA06 conservatively assumes complete elimination of all ISLOCA risk contribution. Performing increased testing of PIVs would not significantly reduce Inceatse leak the ISL.CA event frequency. Nor is it practical to perform more frequent tests. This is because incrase eak- Reduced ISLOCA PIV testing cannot be safely performed during power operation and would require a plant 113 testing of valves frequency shutdown. Plant transition to shutdown introduces risk and additional costs due to lost in ISLOCA paths generation. For SAMA purposes, increased PIV testing is conservatively assumed to reduce the ISLOCA frequency by 50%. Thus, the PRA case upper bound benefit is less than $111 K

0.5 =

$56K and is judged not cost beneficial.

Not cost beneficial. PRA case CONT02 conservatively assumes guaranteed success of all containment isolation valves. At Seabrook, isolation ofcontainment penetrations is typically performed using motor operated valves (MOV), air operated valves (AOV) and check valves (CV), and combinations of these valves, depending on the operational function and isolation Install self- requirements ofthe specific penetration. Check valves are considered to be self-actuated valves.

114 actuating Reduced frequency MOVs and AOVs automatically close upon receipt of Engineered Safety Actuation Signals.

containment of isolation failure Containment penetrations are either closed (isolated) or if open. automatically close upon receipt isolation valves of reliable Engineered Safety Actuation Signals. Self-actuated valves are judged to not significantly improve the reliability of the containment isolation function. For SAMA purposes, the benefit of a self-actuating valve(s) is assumed to contribute 50%/o to the containment isolation function. Thus, the PRA case upper bound benefit is less than $834K

0.5 = $417K and is judged not cost beneficial. Refer to SAMA# 193, CS-V-167.

11 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A Sab C d Seabroorro 0: Se tatio:n f of 2.1::

.. s c.Risk Mutirpl:r tyEvaluation xsingues ,,itii Sabrook ..... .:t .. .Upper S MDiscussion, Numbe rovement PRA Case Beniefit at B-e.e..tat Estimate:'..Eouaduatson Locate residual Reduced frequency Reducedrrequenc Not cost beneficial. PRA case LOCA06 conservatively assumes that ISLOCA events do not 115 heat removal of ISLOCA outside LOCA06 $59K $112K >$IM occur. The cost of relocating the RHR system function to inside containment is expected to ontinent containment significantly exceed benefit and is judged not practical.

containment Institute a maintenance practice to Reduced frequency Not cost beneficial PRA case NOSGTR conservatively assumes that SGTR events do not occur.

119 perform a 100% of steam generator NOSGTR $181K $345K >$500K The cost of 100% inspection each refueling outage is expected to significantly exceed benefit.

inspection of tube ruptures n Costs for this item were estimated to be >S3M in Kewaunee. Beaver Valley and Calvert Cliffs steam generator License Renewal submittals.

tubes during each refueling outage Increase the pressure capacity Eliminates release of the secondary ptwyt h side so that a npathwato the Not cost beneficial. PRA case NOSGTR conservatively assumes that SGTR events do not occur.

121 steam generator following a steam NOSGTR $18 1K $345K >$500K The cost of analysis and design to increase the SG secondary side pressure is expected to tube rufollowingra tube significantly exceed benefit and is judged not practical.

would not cause ratore the relief valves rupture to lift Route the discharge fotm Not cost beneficial. PRA case NOSGTR conservatively assumes that SGTR events do not occur.

the main steam The cost of a main steam safety valve spray system to reduce fission product release during safetyu valves SGTR is expected to significantly exceed the benefit. It is noted that Severe Accident struc he a cequces Management Guideline SAG-5, Reduce Fission Product Release, includes guidance and 125 swature where a consequences generatoroftube a NOSGTR $181K $345K >$500K procedure steps for use water spray steam 'l euto fS of external eess spraying sources for fission product plume reduction including would condense rupture possible reduction of SG releases.

the steam and remove most of

Reference:

SAG-5. Reduce Fission Product Releases. Section B and Table 7.

the fission products 12of55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A Table X-2 .. .

Ttation.Sensiivity Evaluatio usimSeismicRisk.Multiplerofi1. . .. .". :

(. M

12 n l ia e a ~

firr me: R To :F 1 ;i 1 !: !k![ :!3 .* : ;: ii !: : * ; i* .*. -: !. :!ii** ~

i !). 3..:i .:: . :'-* :!.!.:i.:i:!ii:.:i... :SL.!1(' i L:!*I i' . :: :i . *r-.,,!g! :"i:!,: i ![.i[i'~ '?:i[*?;

'I:i!:!::!?5: :;!~ .:!: iqi.! ,:*'3 -,.[: "

S ,.*, Potentiall .l.:t-.ad Dicusin .... : : PRIe :ii.pevaluation cost..*,:i:?.EI Benrefirti

.I-.l~u Number.:ý ~

...**Ilmprovement e . . .. .E:.tima.

. .*:.:. ____. ... __-_..__::.*

__.-:_..

issoBeei ___. _____ i*:liil:*:* !2L]X *:.lx a iii'!:l. .

simtX e,. . . . . . . ................................ .....................

I Install a highly reliable (closed loop) steam generator shell- Reduced Not cost beneficial. PRA case NOSGTR conservatively assumes that SGTR events do not occur.

126 side heat removal consequences of a NOSGTR $181K $345K >$500K The cost of installing a passive, closed loop SG heat removal system is expected to significantly system that relies steam generator tube exceed the benefit and is judged not practical.

on natural rupture circulation and stored water sources Vent main steam Reduced Not cost beneficial. PRA case NOSGTR conservatively assumes that SGTR events do not occur.

safety valves in consequences of a NOSGTR $181K $345K >$500K The cost of analysis and design to locate main steam safety valves in containment or route 129 scontainment steam generator tube existing Safety valve discharge to containment is expected to significantly exceed the benefit and rupture is judged not practical.

Add an Improved Not cost beneficial. PRA case NOATWS conservatively assumes that ATWS events do not 130 independent availability of boron NOATWS $148K $282K >$500K occur. The cost of installation of an independent boron injection system is expected to boron injection injection during significantly exceed the benefit.

system ATWS Add a system of relief valves to prevent Improved equipment Not cost beneficial. PRA case NOATWS conservatively assumes that ATWS events do not 131 equipment availability after an NOATWS $148K $282K >$500K occur. The cost of installing additional relief capacity is expected to significantly exceed the damage from ATVS benefit pressure spik-es during an ATWS Install an ATWS sized filtered Increased ability to Not cost beneficial. PRA case NOATWS conservatively assumes that ATWS events do not 133 containment vent remove reactor heat NOATWS $148K S282K >$500K occur. The cost of installing a filtered vent sized for ATWS heat removal is expected to to remove decay from ATWS events significantly exceed the benefit and is not practical.

heat Install digital Reduced probability Not cost beneficial. PRA case LOCA05 conservatively assumes that LOCA events, as a result of 147 large break of a large break L 05 $217K $412K >8500K pipe failures, do not occur. The cost of installing a digital break detection system is expected to LOCA protection LOCA (a leak significantly exceed the benefit It is noted that a benchmarked plant estimated the cost of this system before break) type of modification to be -$2M.

13 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachmnent A TableX- A ebokSainSniiiyEauation using Seismnic ik utile of2.

SAM* Candidatesarerom:Seabrook ER.Table'F.8# ) ...... .-

Seabrook' Nominal Upe SAA Ptential: ~ A' B ft Bound - ost a n I I Numrber Imrvmn.Benefit at Estimate- Ib Prevents secondary side depressurization should asteam line break occur Install secondary upstream of the side guard pipes main steamn isolation Not cost beneficial. PRA case NOSLB conservatively assumes that steam line break events do 153 up to the main valves. Also guards NOSLB $6.6K $12.6K >$500K not occur. T'he cost of installing secondary side pipe guards is expected to significantly exceed steam isolatiorn against or prevents the benefit valves consequential multiple steam generator tube ruptures following a main steamn line break event Modify SET'S Not cost beneficial. The PRA case OSEPALL conservatively assumes guaranteed success of all design to Improve reliability manual actions to align and load the SEPS diesel generators. The current design requires the accommodate of onsite power: operator to manually align SET'S to the desired bus and to manually load SET'S to ensure power is 14 atmtcbs reduce SBO CF OEAL $8 10 S5k available to needed components. The proposed SAMA is to install a control system to perform auomaticg bus contribution: N05910 6K 3K>70k these actions automatically. The cost of the automatic control system is estimated to exceed the loading andndn benefit PRA case OSEPALL is judged to be more representative of this proposed SAMA than automatic bus reove dependenccion the original PRA case NOSBO. This is because OSEPALL more accurately models elimination alignent ooprtrof the SET'S manual actions compared to NOSBO, which credits success of dhe EDGs.

Install alternate offsite power Improve offsite Not cost beneficial. PRA case NOLOST' conservatively assumes elimination of all LOST' events.

source that power reliability and Cost of installing, alternate offite power source that bypasses the current switchyard power bypasses the independence of source is expected to significantly exceed benefit 156 switchyard. For switchyard and SF6 NOLOST' $704K $1.34M >$7M Implementation cost was assumed similar to an estimate performned at Seabrook Station which example, use bus duct; allow 44AM would supply campus power directly to plant buses I & 2. A study performed to implement this campus power restoration of offsite change determined it necessary to replace and/or install new transformers and switchgear at an source to power within a few estimated cost >S7M. As this value substantially execeeds the upper bound benefit of Sl.34M, no energize Bus ES hours more refined estimate is warranted.

or E6 Provide independent AC Rdc D f]n power source for Reduc CDFofln 17 battery chargers. teuneSB s: ten SAMA #157 was show to be potentially cost beneficial in the original study. The 2.lx p5Froviexaporale, battery life to allow INDEPAC 548K 595K $30K sensitivity evaluation furthers the degree to which this SAMA is beneficial.

generat ortobl additional time for charge station rcvr

__ _ battery _ _ _ _ _ _ _ _ _ _ _

14 of 55

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure /Attachment A rabsIx-2

-I :" .4 ..4 Seabrook:Station Sensfiviy Evahation-usinSeismic

. Risk Multiplier of2.1* -:::. .: . .. i~ '.:=

.,.-..:' ... : *4 .... ,.: .. .. * .. .. * 'I ". , i.,

i* t . . - ..

~~S.AMIA~~

Cadiaerfrom Seablrook ER TIab)eR8-1) 44 41r Poenia Noia 'BunCs SAMA Discusson Improvement

- ,.

i .

PRA:Case

.

R]Lalea'flatE-luon44

'Benefit at Estimat , ; , .

Reduce CDF of long term SBO In Not cost beneficial. PRA case INDEPAC conservatively assumes that station batteries have AC Instll aditinal sequences; extend 159 Iatteries sequen o allow INDEPAC S483K $94.5K >SIM power available for battery charging. The cost of installing additional batteries is expected to batteiosalatime for significantly exceed the benefit.

recovery Not cost beneficial. PRA case NOSBO conservatively assumes elimination ofall station blackout events by assuming guaranteed success of onsite diesel generators. Thus, the benefit of Modify EDG Alternate cooling to modifying the DG cooling system is conservatively high because loss of cooling does not jacket heat both EDGs would contribute significantly to DG failure. The cost of installing a back-up diesel cooling water system exchanger service reduce CDF long is expected to significantly exceed the conservative benefit. Backup diesel cooling water system water supply and term sequences was also addressed in original SAMA #20 with estimate of>SlM. A reduction in seismic risk return to allow involving LOOP and >M ould not be significant unless the backup cooling water system is also seismically rugged, which 161 timely alignment NOSBO $326K $620K would further inSrease ost.

of alternate tower. A loss of cooling water service water / Approximately 1800 GPM of water to the existing EDG jacket water heat exchangers would be source (supply & cooling tower with a required to support full load operation. Existing firewater system capacity is limited to 1500 GPM drain) from LOOP could result with limited water availability. Other alternate water sources limited to much less. A pump with firewater, RMW, in EDG failure and flexibility of suction source, such as that used in SAG-I. but with higher capacity would be DW, etc. non-recovery needed to achieve the benefit of this SAMA. The lower capacity SAG-I pump with associated hose, fittings and connections cost was $759Y. The expected cost to implement SAMA 161 will exceed the upper bound benefit of $620K.

Extend long term operation of EFW without operator action for CST makeup for Increase the sequences that do Not cost beneficial. PRA case CST0I conservatively assumes a continuous, successful CST 162 capacity margin not go to cold CSTO1 18.1K $33.6K >$100K suction source for EFW. Cost of expanding capacity of the CST is expected to significantly of the CST shutdown. Enhance exceed benefit CST margin for design-basis seismic event with cooldown via SG and transition to RHR 15 of 55

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure /Attachment A Table;X-2 ': Seabrook Statio Sensiiitiiy Evaluation.usiug2Seism.*...sk.,.. p...,.of 2.1 .

Candidates are from Seabrook ER Tale F.8 1).

SAM.

S..'. Upper Seabrook 'onta. ' Dssso- ' '" Nominal: ~ *.rI vlato S SAotentiCsa.Blefta Improvement . Bound ' Cost

. .. B t Benefit at Estimate .................................

_______ _____2.1i'

Reduce CDF of SBO sequences by Not cost beneficial. PRA case TDAFW conservatively assumes guaranteed success of the improving overall turbine-driven EFW pump. Thus, the benefit of installing an additional turb.'e,'riven pump is reliability of EFW conservatively high. Installation of an additional turbine-driven EFW pump is not practical and system independent the cost would be expected to significantly exceed the conservative benefit The reduction in of AC power. An seismic risk would not be significant unless the new equipment is also seismically rugged, which Insall third BFW additional pump >LI would further increase Cost.

163 pump (steam- mievels 2 hbeefi by TDAFW S210K S400K This modification was assumed to be the equivalent of adding one new high pressure injection drien)maintaining .pump described in SAMA 26. A discharge path, suction source and supply from the Main Steamn coverage of SG header would have to be routed, analyzed and supported. Changes to how the safety related EFW tubes thus reducing pumps are configured would require substantial change to the foot print of the system and flow the release potential analysis in addition to procurement and installation of the pump, piping and control valves. A for induced SGTR detailed estimate would far exceed the upper bound benefit of $400K and no more refined cost given high pressure estimate is warranted.

core melt sequence Modify 10" Possible Condensate Filter enhancement of 164g 2V-nhfeale t a long term core ~ Tl 1.K ~ 6 ~ K Not cost beneficial. PRA case CSTOlconservatively assumes a continuous, successful CST 14 26icfeae damage sequences CSO 81 3.K >4K suction source for EFW. Cost of modifying the condensate flange is expected to exceed benefit fire hose adapter that credit CST with isolation makeup.

valve RWST fill from firewater during containment Could enhance long injection - term containment 165 Modify 6"RWAST injection sequences NORMW $158 $298K $50K SAM #165 was shown to be potentially cost beneficial in the original study. The 2. lx Flush Flange to that would benefit sensitivity evaluation furthers the degree to which this SAMA 'isbenieficial.

have a 2'/2 inch from RWST female fire hose makeup adapter with isolation valve 16 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A rable X2 .:.Seabrook Station SensiiMty Evaluaion.iusg Seismic Risk Multiplier of2. ...

,. . . . . ,: . . . , . . . . ,. . ::

. ... . . : ... :.. . . . .. .. : , : . , . , .. . .. . . . . ... .. . ., . . ... * . .. .. . . . . . . .. . . . . .. .* . . . . ., , .. . .. ... ... . . . .. .. . . .i . . .. . .

rSAMACandidates are irom Seabrook PR Table F.8-1): F SeabrookPoNoeitial SrUpperI I SA.MA DicussionPRA Case

.. Imroveent Becilt at. enefit'at ot

-Estimate valuation E~id j Nu..ber.I' 2.. .. , .

Install Reduce CDF indeendnt romNot sal ontibuton cost beneficial. PRA case RCPLOCA conservatively assumes that RCP seal LOCA events 167 inijection pump RCP seal LOCA RCPLOCA $173K 8370K >$IM are eliminated. The cost of installing an independent seal injection pump/systemt with automatic Plow volume events driven by str sepce0osgiiatyece eei pump) with seal cooling sati xetdt infcnl xedbnft automatic start hardware failures Install Reduce CDF independent seal contribution from Not cost beneficial. PRA case RCPLOCA conservatively assumes that RCP seal LOCA events 168 uinection PUMP RCP seal LOCA RCPLOCA $173K S370K >$IlM are eliminated. The cost of installing an independent seal injection pump/system with manual (low volume events driven by str isepced to sinficatlyecd bnfit pump) with seal coolingexet s rcn ecedeei.

manual start hardware failures Reduce CDF Install contnribution from ndependent drC ivealbyC Not cost beneficial. PRA case RCPLQCA conservatively assumes that RCP seal LOCA events 169 c argn seal cooling RCPLOCA $173K $370K >$500K are eliminated. The cost of installing-an independent charging pump with manual start is (high volume ardware failures-, expected to significantly exceed benefit.

paump) withr improve decay heat manualstart removal using feed

& bleed Replace the Positive Displacement Reduce CDI' Pump (PD?) with contribution from Not cost beneficial. PRA case RCPLOCA conservatively assumes that RCP seal LOCA events 170 a 3rd centrifugal RCP seal LOCA RCPLOCA $173K $370K >S500K are eliminated. The cost of installing a centrifurgal pump, independent of cooling water, in place charging pump. events driven by oftePPsati xetdtosgiiatyece eei Consider low seal cooling fh Dstrisepcetosgfcalyxedbnft volume and hardware failures cooling water independence Evaluate Reduce CDF installation of contribution from coolingthardwarelRCtraCnsientK w370Kseal Not ocost beneficial. PRA case RCPLOCA conservatively assumes that RCP seal LOCA events 12 in the RCPs being folnailres aresutn in L 13K $7K>I are elimdinated. The cost of the RCP shutdown seals is expected to significantly exceed benefit.

developed by I C falrsreaultn inC Westinghtouse RCselOA events 17 of 55

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure /Attachment A Taile'X-2 A-' Seabrook'Siation Sensitivity EvaluationusinigSeismic RisckMulitplierof2.1' -. -

SAMACandidades'are-from Seabroo!kER Table F.l.l)'

Seabrook Norninal:*

.Potential.,Bun Cost SAMA Discussion PR~A Cat Benefit at' valuation E~t um Je Improvement',~ Beei 2tl Esimt Improve reliability of reactor scram by Provide alternate providing remnote-scram button to manual capab~ility to Not cost beneficial. PRA case NOATWS conservatively assumes elimination of all ATWS riskc 174 remove power remove rod drive NOATWS S 147.4K S281.4K >$500K Cost of modifying the scram system to provide an alternate scram button is expeced to exceed from MG sets to power should the benefit CR drives reactor trip breakers fail; reduce ATWS contribution Install fire Improve fire Complete. Fire detection is installed in the Turbine Building Relay Room.

175 detection in detection and FIRE2 --

turbine building manual suppression

Reference:

151642.919 and 93DCR021 relay room actions Not cost beneficial. PRA case FIRE 1 conservatively assumes complete elimination of the control room fire initiating event that results in a PORV challenge. The proposed SAMA is to improve operator procedures for coping with a small LOCA due to fire and opening of a PORV. The procedure change would not eliminate, but potentially reduce the significance of this event.

Fire, induced Therefore, the estimated benefit is conservative for this SAMA_ This SAMA is judged to have LOCA response Possible reduction >$20K marginal benefit due to existing design and guidance to minimize potential for inadvertent PORV 179 procedure from in CDF if mitigating FIREM 58.K S15.3K interaction. Also, the likelihood of LOCA with control room uninhabitable for a long period of Alternate fire-induced LOCA 41K time is judged low.

Shutdown Panel Anticipate additional remote indication and controls will need to be installed to achieve the benefit of procedural enhancements. The major Abnormal Procedure change alone has an estimated implementation cost of $ 15K. Total cost expected to significantly exceed the upper bound benefit of S 153K.

PRA case SEiSMICO I conservatively assumes complete elimination of relay chatter. As stated in the ER SAMA report, there is significant uncertainty in relay fragility and this is not necessarily

>$0K addressed by component replacement and is beyond state-of-die-art.

Ipoerly Reduce CDF 1mroerea contribution from SEISMICOI S214K $49 The scope of this proposed SAMA would include approximately 34 relays associated with the chatter fragility reaychffr 30K ED~s and load sequencers. The expected average cost of a relay replacement is $20K each. As the implementation cost of replacing 34 relays (>$600K) exceeds the upper bound benefit of S409K, no more refined estimate is warranted. It is noted that a SAMA related to the seismic

______ __________

_________ ______ ______ _______upgrade of relays for Diablo Canyon was estimated at >S4M.

18 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A table"X-2 i.'... Seabro6okStati6n Sensitivity Eva.uation.using.$eismic i lMult.p.ier.of.2.1 Candidates are from Seabrook ER Table F.8-1)............... pSAMA .. ... ,

Seabrook Pot.ntial .

poetilBound . - , ,Nominal :UPP : . ..

Cost Eauto ..

SAMA Discussion PRA;Case enefit at Benefit at *.: Estimate Evaluation Numnber'-.. . 2i Improve seismic Improve component Not cost beneficial. PRA case SEISMIC02 conservatively assumes no seismic failures of the 1 c2 canpacity o s frility and redue SEISMIC02 <$1K <41K >$500K EDGs and turbine-driven EFW pump occur. The cost of upgrading the EDGs or the TD-EFW EFW pump contribution to CDF pump is expected to significantly exceed benefit Purge path is large Control/reduce opening. Reduce Not cost beneficial. PRA case PURGE conservatively assumes that the containment purge valves time that the exposure time of are continuously in the closed position and are not opened periodically. The cost of procedural 184 containment open path, improve PURGE <$1K <$1K >$20K changes is expected to significantly exceed benefit In addition, it is noted that historically, the purge valves are reliabilitylavailabilit exposure fraction of the containment online purge (COP) supply and exhaust paths is less than ir openin postion opn position failure Y Of Cicontribution reduce CI 109/a, which is judged not significant to large release Improve Not cost beneficial. PRA case CISPRE conservatively assumes complete elimination of pre-Install containment existing containment leakage. The proposed SAMA is to install a leakage detection system containment reliability by CISPRE having the proper sensitivity to detect leakage. Thus, upon detection of a leak, actions would be 186 leakage reducing the GQN-k4m S23K 543K >$500K taken to identify the leakage source and take actions to reduce leakage. PRA case CISPRE is monitoring potential for pre- judged more representative than original PRA case CONTO0. This is because CISPRE more system existing containment accurately models the benefit of a leakage monitoring system compared to CONTOI, which leakage assumes elimination of containment failure events due to overpressure.

Not cost beneficial. PRA case LOCA06 conservatively assumes that ISLOCA events do not occur. The cost of installing a leakage monitoring system at the RHR isolation valves is expected Install RI-IR Reduce ISLOCA to significantly exceed the benefit.

isolation valve challenge to RHR >S190K Will require pressure and/or temperature transmitters installed between isolation valves. Alerts 187 leakage by identification of LOCA06 $59K $112K operator that lower pressure piping is being challenged by RCS leakage. This enhancement is monitoring upstream valve similar to SAMA 111 contained in the Kewaunee License Renewal application. In that system failure application S190K, the lowest of three estimates assessed was used for an implementing cost basis. The expected cost to implement SAMA 187 of$190K will exceed the upper bound benefit of $1 12K.

Modify or Allow all equipment analyze SEPS tob nflowg capability: I of 2 LOSP with EDG Not cost beneficial. PRA case Iof2SEPS models the change in SEPS success criteria from 2 of 2 189 SEPS for LOSP fai t lof2SEPS $63K 5120K >5300K DGs to I fo 2 DGs. The cost of analysis, hardware modifications and testing is expected to non-Sl loads, 2 of sucressful start and significantly exceed the benefit.

LOSP SI 2 for leadsload loadeof strS loads Of SEPS Add Elim~inate current Add requirement for Not cost beneficial. PRA case NOSBO conservatively assumes elimination of all station blackout 190 synchronization capability to dead bus from SEPS transfer to NOSBO 5326K $620K >SIM events. The exceed significantly cost of installing benefit synchronization capability to the SEPS diesel is expected to SEPS Diesel normal power I I I I 19 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A rable X-ý2 Seab~rook Station Sensitivkiy Ealuiti~on usin-,Seism'ic Risk Multiplier of211 . Jlý

,SAMA dCandidatesare.from'Seabrook ER TabeF.II*e F.8-1)

Po e tial . . -omi.. . . , .- . . al-. . U.pper U po . ., . ." a. o. ... .. . . . ..

AMA' mber mproveme ..Diesn. ... . FkCase R

..- Benefit at.

.:Benefit at Coslua Estimate..,i ion i Potential for some This SAMA is from Reference 3, RAI 5n and is evaluated for sensitivity to the 2. Ix risk increase.

Remove the 135F improvement in Not cast beneficial. PRA Case PCTES assumed elimination of 100% of the inadvertent failure of 191 temperature trip PCCW reliability by p <$IK <$IK >$100K the redundant temperature element/logic as a failure mode of the associated PCC division for of the PCCW eliminating both loss of PCCW (A/B) initiating events (during the year) and loss of PCCW (A/B) mitigative pumps consideration of function (mission time). The results of this case study show that inadvertent actuation of the spurious trip temperature/element logic does not contribute significantly to the system unreliability.

Reduce CDF Install flow contribution of CB SAMA #192 was shown to be potentially cost beneficial in the RAI submittal, reference 3. The 192 orifice in fire flooding due to fire NOCBFLD S338K $644K 5200K 2.1x sensitivity evaluation furthers the degree to which this SAMA is beneficial. SAMA#192 protection system protection pipe was identified in RAI Ia (Reference 3) break Eliminate Reduce containment SAMA #193 was shown to be potentially cost beneficial in the RAI submittal, reference 3. The 193 CSVp67AC isolation failure V167AC $403K $766K $300K 2j1x sensitivity evaluation furthers the degreto which this SAMA is beneficial. SAMA#193 pwdependence CSoVi 67 was identified in RAI 2f (Reference 3)

Purchase or manufacture of a gagging device" Improve release 194 that could be mitigation for a MSSVRS <$1K <51K >530K This SAMA is from Reference 3, RAI 7, item c and is evaluated for sensitivity to the 2.1x risk used to close a SGTR event prior to increase. Not cost beneficial based on conservative PRA case and estimated cost stuck-open steam core damage generator safety valve 20 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A

,:,TAb 6ok' S fiýifg-ensite Ia. 4ýýOiýAmc icAtAgiiý4i 46 bl;6i V' ti asieit'vents are W36abro6kR si J1, P, ji r

., . ., ..... bin t e * . .. .. . . . ..

. ... . . 'I .. I. . ..

elimintionrolallltationblackot evets'by ssum"n guarnteed ucces Notna cotbnfcal R aeNOB osratvl sue conserative beeIt No cost benfiia PR aeNSB osraivlsue W1pov elcria syte reiailF is exetdtiinfiatyece h

" ............................ "_ _ _ _ 8 OO Not cost(A A16 PRA case NOSBO beneficial. CISPRE conservatively assumes cmlt

____,- __"____,__,_"____'*q Smal pe-eistng 186elimination all station blackout elimination of prllexstaiong events leaasuige lcontainments by assuming aouadranteed Thearoposed sucAciss success close-IA faisEPSruof onsite diesel Teusc generators. dsg reqies the oeratpopeo manually alonsite

1

I2AHOPfa.FRl ndente clHadwr

9,ouur

oril 14,prcdua S0, #b155 chang NOSBO $326K toinstal of adleakael detecations Thsysthem haveingth sensityivitye todetec

$620K >$IM electrical power system to add or modify DZ.CIS.PREE IS fo to elimnat or,4reduce155CISPR 8323.K S42.6K > leakriage Thspone deste ctionadorm lek a y a DcinG df SDG towimproveeliminate ae udbto ideoe~lm ntDpGifyG SI Siglfaures likeihoo ofmallpreexis100K thelueakagesousrcaiel is conservatively and take actonst h Thetof high.

blckontainments reducelleakge cost of inslling an anot leakage.minggproposed adtioat the additional cotof suceiss Da to Smal leakage~impov pe-eistng 186elimination ekg of pre-exstaiong ntlgcthrdware en~e system freleakagidtecio is expected improve electrical system reliability is expected to signifioanty exceed the tosinfctl exceedth C1,#15ISBOE $326K $42.6K $1M eleatriage conservative Thspone sys te tiona c ormdf leka y cinD wudbto ideoe/

benefet. lm nat ify ae DGDGIB.FR3.)S contimn to elimnat or,reduc Not cost beneficial. PRA case TOSDA conservatively assumes

2 unide1 faied Hardw e or pnsteed suesel of th turbine-drav Ege Th benefit ofthe us, peutors.

Turbilrneselyh.os of tu ie dan additional installing p mionsee rvag Ntie thig o

failsntifie toiruoe i cstwoaldwbe system oreiagifit expeeed is te ons exceednth eliminate opratredcaIP toSina E $31 4.Kla e hs pndtction onetsaleakproponsewd ailbetneddcm SA i taeto i dnstally Top Even lOelho Notconfo c n PRA es thesla costsystem l to-perform beneficial. a ecase actionsaSsPued atomrd c NT etssumes latially.

ecroenvatively omwt cost ofth athe Opent Cis #193 tmidentifie leakage guaimnateoe su iensefismcrst antoalticgaohtrdwar Thne redution of system ashowng ol ed lestima aligco bexpefitedt.

o dtoexcdtion fosconbeipoent esgiiatuls benecalhe prposdiAesi thee e mClPen pe-exisolation Hardware change torel am nate g40Krato rst a geurrente s sensitivit a p y th the degree frvalv enmC L 67 MOV C o w dependene to Notwhich this SA0A TePRA.

cost beneficial. i$50s caseT al.e SEALL benefci conservatively assumres success of the taurbine-divens o pump. Thusloa theS EPS ieselo Operatr fais to # 54guaranteed i venupet mpre s o nservatorto vaealy ahigh.

genstalling Thn adiioaur bin e-des losrbie DEreiven to action S20 39 M Isalalabetion oaneededitimonentsthrie propoed E Apmp is nt practiall an SI3F Pumpa eliminate

163 fails to run ~~atheti costrwouldsysemexpetmted tosinfctl exceed the osraie benef it Top Event CIS, #193Notetal cost beneficial. bR ased on aonsuedrvieplyassumentosO ihF

~ ~~~

6~slto ~

adaecag ~ oeiiae ~ ~ V6A ~ ~ ~ Pe.X3~

43 ~

76 ~ ~~

30.succe19ws~gaate shown t bne-dpotental to cost beneicia Thns the beneIto al e Driven6 TurbinO M V A po e d p n e ces binstall , re ern c 3.io a T hrie -d venstv y evaluais onse uratihe rs theidg ree thos whichthi i expeted osinfctyexedheosraiv beneficial fIlst u 21 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachmnent A gX3 -, 1' lsrk;6i

'.1 1,,

oi~

so,J nstry toutoio1,p siiyns Hi 4.ej'.

I I Sr" i .

.............. ..:...,...........

.....:f..- ;: ..... . I l .'*. Nomfinal Esimat:,?:

Evaluation Basic Event i I i ,vnt .. :C: e, ':., Benefif at': Bound:it BI. : I 1I

. . :. ~

i~~~~ss~ Mksj~:- Ie~ , iI ;ii:I'! L.efV :... ...i1 r?,,; I.: R iui Not cost beneficial The PRA case OSEPALL conservatively assumes Operator fails to #154 guaranteed success of all manual actions to align and load the SEPS diesel close SEPS breaker generators. The current design requires the operator to manually align HHLOSEPIQ.FA from MCB given closure of SEPS breaker to OSEPALL $683K $130.2K >$750K SEPS to the desired bus and to manually load SEPS to ensure power is seismic event eliminate operatoravailable to needed components. The proposed SAMA is to install a liminate o action control system to perform these actions automatically. The cost of the automatic control system is estimated to exceed the benefit.

Not cost beneficial PRA case SEPES conservatively assumes elimination of all SEPS DG hardware failures (assumes guaranteed success of SEPS 1-SEPS-DG-2-A #9. #14, #189, Elimination of DGs). Thus. the benefit of modifying the SEPS electrical power system to SEPSDG2# FR3 fails to run within all potential for SEPS failure SEPES $83.6K $159.2K >$300K add or modify a DG to improve/eliminate DG failures is conservatively

EP8D A.FR3 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months high. The cost to analyze existing SEPS DGs, or installation of an additional DG to improve electrical system reliability is expected to significantly exceed the conservative benefit Not cost beneficial. PRA case SEPES conservatively assumes elimination of all SEPS DG hardware failures (assumes guaranteed success of SEPS 1-SEPS-DG-2-B DGs). Thus, the benefit ofmodifying the SEPS electrical power system to SEPSDG2.FR3 fails to run within all potential for SEPS filure SEPES $83.6K $159.2K >$300K add or modify a DG to improve/eliminate DG failures is conservatively 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months ahigh. The cost to analyze existing SEPS DGs, or installation of an additional DG to improve electrical system reliability is expected to significantly exceed the conservative benefit Operator fails to close containment Provide a hardware This SAMA basic event candidate is related to basic event CSVI67.FO

10 isolation valve modification (additional signals OC.2S $5.5K $10.5K N/A and SAMA #193, which has been shown to be potentially cost beneficial HMOCL2Q.FL CSV-167 locally or remote capability) to based on assumed replacement of MOV with FC AOV.

given medium automatically close V-167.

seismic event DG-IA Engine

11 Driven Lube Oil Provide hardware modification Not cost beneficial based on assumed elimination of DGP I 15A/B basic DOPII5ASS Pump fails to run to improve lube oil pump DGP 115A/B $19K $35.7K >$100K event RRW SE3, LL3, SE1, LL4 failure contribution and estimated cost to reliability add hardware (additional pump) needed to improve reliability.

Not cost beneficial PRA case NOSBO conservatively assumes elimination of all station blackout events by assuming guaranteed success

12 D-lA fais to art of onsite diesel generators. Thus, the benefit of modifying the onsite DGDGIA.FS on demand #9. #10, #14, # 155 NOSBO $326K S620K >$lM electrical power system to add or modify a DG to improve/eliminate DG failures is conservatively high. The cost of installing an additional DG to improve electrical system reliability is expected to significantly exceed the conservative benefit.

22 of 55

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure /Attachment A 23 of 55

United States Nuclear Regulatory Commission SBK-L-l 10671/ Enclosure /Attachment A 24 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A Il!1

,ýfrqhi!ý~

j:N

!SirokOtton nstVity!Evaluat~ion

I',Ie.l

of Top Basic te'vIsts'otributino. oRL3 sn S'.l; . *. ,L : . . Be.!ise:!it ati.:i Nominial' ;.

Iý Jppler: '!

'

sm i!Mlilejfl I

~

I 1 1 1 -ikh

.1]ý ii Id i DOM ti "* : " I L' :!i :*" 11 :i' ',2 ,1,i.

l .x:t,,

Bound" i! 7costs1t!;

i ii:ai:.

I ]RA on i I

.As:I.c!.t.

i d;.;S:iI MA:I,,:ii s)i:

., .:.i.!i.:i::.l. *Iii.1 Ii; !

I i* i'.? i lk.f IaIl Not cost beneficial based on assumed elimination of all risk associated with TE-2171 and TE-2271 failures. PRA case PCCTS conservatively assumes guaranteed success of the TE function for PCC Trains A and B that could cause an initiating event (1Bmodel) and/or fail PCCW during PCC Train B mission time (support system model). Hardware changes that would

3 Temperature Improve PCC TE reliability. >3250K significantly improve temperature control reliability., for example adding Element CC-TE- eliminate potential for temp. PCCTS $61 K $116K 42SOK additional redundant instrumentation and controls, is expected to CCME2271 .FZ 2271 transmits false element failure significantly exceed the conservative benefit.

low Design changes to implement this type of action would be similar in nature to SAMAs 147, 174, 186 and 186,which were estimated to exceed

$500K. As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

Not cost beneficial based on assumed elimination of all risk associated with TE-2171 and TE-2271 failures. PRA case PCCTS conservatively assumes guaranteed success of the TE function for PCC Trains A and B that could cause an initiating event (E model) and/or fail PCCW during PCC Train A mission time (support system model). Hardware changes that would

4 Temperature Improve PCC TE reliability, >$250K significantly improve temperature control reliability, for example adding CCTE2171.FZ Element CC-TE- eliminate potential for temp. PCCTS $61K SI 16K additional redundant instrumentation and controls, is expected to 2171 transmits false element failure significantly exceed the conservative benefit low Design changes to implement this type of action would be similar in nature to SAMAs 147, 174, 186 and 187, which were estimated to exceed

$500K. As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

Not cost beneficial. PRA case TDAFW conservatively assumes guaranteed success of the turbine-driven EFW pump. Thus, the benefit of 5Turbine Driven installing an additional turbine-driven pump is conservatively high.

Pump FW-P-37A D163 TDAFW $210K S399K >$2M Installation ofan additional turbine-driven EFW pump is not practical and FWP37A.FR fails to run the cost would be expected to significantly exceed the conservative benefit. The reduction in seismic risk would not be significant unless the new equipment is also seismically rugged. which would further increase cost Not cost beneficial based on assumed elimination of all risk associated with loss of offsite power. PRA case NOLOSP assumes elimination of all

6 Loss of Offsite LOSP events and provides a conservative benefit for ZZ.SY1.FX, which Power subsequent #13, #156, #160 NOLOSP $704K S$.34M >$2M models consequential loss of offsite power following a plant trip event ZZ.SYI.FX to Plant Trip The cost of power system upgrades that would significantly reduce or eliminate consequential loss of offsite power events is expected to significantly exceed the conservative benefit 25 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A 26 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A I'bl X111 Sbiook botin: riiivt' vaH - B'onido.Miid 6t ~ffibiting to XMC-LLpiusin"'of 2.

2f) o., ase,.e T I I Ba:'I Nominal,I Utr

,Assoezated bAMA(s)'I~ ' II 'PiRA aseJ"i 1 Bendit ati Ist !

Descr'iptioa ; ~ Ii .1 A**q::iX I I il*

!i :.':sim.i!

i lIi . .:. J

-pl, Not cost beneficial based on assumed elimination of SWGI IA/B basic event, case E6S is representative of Bus El lB. The PRA case conservatively assumes elimination ofbus faults that could cause an initiating event (IE model) and/or fail the associated power division during mission time (support system model) by assuming guaranteed success of the bus. It is noted that due to their relatively passive design, DC Power Panel do buses are relatively reliable and have a low failure rate. A hardware

11 11B fails to operate Improve Bus El lB reliability, >$500K E6S $812K $156K change that would significantly improve bus reliability, for example EDESWGI IB.FX Top Event DCP, eliminate bus failure >$1 OOK adding a redundant bus within a division,;is judged impractical and is CCF Group BUSFL cxpected to significantly exceed the conservative benefit.

Implementation assumed to involve design of additional bus to achieve improvement in bus reliability with a cost of>$1M. This scope is assumed similar to SAMA # 16 (improved uninterruptible power supplies). As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

Not cost beneficial based on assumed elimination of SWG 1A/B basic event, case E6S is representative of Bus El IA. The PRA ease conservatively assumes elimination of bus faults that could cause an initiating event (IE model) and/or fail the associated power division during mission time (support system model) by assuming guaranteed DC Power Panel success ofthe bus. It is noted that due to their relatively passive design.

do buses are relatively reliable and have a low failure rate. A hardware

12 fails to operate Improve Bus EA IA reliability $2K $156KK change that would significantly improve bus reliability, for example EDESWGI IA.FX Top Event DCP, eliminate bus failure 41-00K adding a redundant bus within a division, is judged impractical and is CCF Group BUSFL expected to significantly exceed the conservative benefit.

Implementation assumed to involve design of additional bus to achieve improvement in bus reliability with a cost of>$IM. This scope is assumed similar to SAMA #16 (improved uninterrupdble power supplies). As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

SW Secondary Not cost beneficial based on .assumed elimination of SWV5 basic event

13 Isolation MOV SW- RRW LL3, LIA, SE1 failure contribution. A hardware change that would V-5 fails to close on Improve SWV-5 reliability, SWV5 $17K S34K >$I00K significantly improve isolation valve reliability, for example adding SWVS.FO demand eliminate valve failure redundant valves for isolation of SW to Turbine Building SW loads, is expected to significantly exceed the conservative benefit Not cost beneficial. PRA case NOSBO conservatively assumes

14 DG-1A fails to run #,0#14#155 NOSBO $26K $620K >$1M elimination of all station blackout events by assuming guaranteed success DGDG1A.FR3 for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of onsite diesel generators. Thus, the benefit of modifying the onsite electrical power system to add or modify a DG to improve/eliminate DG 27 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A I

28 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A S Sti on nsittwv ioibiit'to luaino.T6 as E RCvat1 of,2,i.i... -..-. I ' *

.,a l** 5 : '. .-.- I~eab r°il : " I.H .bi. '.ii .."II. . it .. .'g. . . " g I

. I':1 ; ": : H::

. . . .. . .

...,.,.[.,.I.,....::. I.I

- new:*eq"imen i a se r whic .. f uld incEre a Is I I

1' Turb.ine..

Driven.-..- ;::!:! *alllation I.nst of.an adi turine-dive

-oa ..W pum is no pracica.an Not cost beneficial. PRA oase TDAFW conservatively assumes gOaranteed success ofcthe turbine ariven EFW pump. Thus, the benefit of

1 urbie Drveninstalling an additional turbine-driven pump is conservatively hig~h.

IWP-7 Pull Tubn Driven 20K $39 > Installation of a additional turbirie-driven EFW pump is not practical and the cost wouls expected tt significantly exceed the conservative FWP37A.FR to n fu l failo benefit. 'fe reduction in seismic risk would not be significant unless the new equipment is also seismil rugged, which would further increase cost.

Not cost beneficial based on assumed elimination of operator faslure to feed SG. A hardware chag to provide automatic b ef d flow to dSe faulted

2 Operator establishes Hardware for automatic feedpower system ul significantly reduceoim endaeualatedii fautedI.FA flo, HH.XOEF flowto poentialforProced$8.6s$16.rKe$100gProceduescdirctingetisuactoniarelufficintlyedeailed fed elimnate HH.OEWIFA SG operator failure to feed SG the PRA human reliability analysis. Any changes to procedures are judged not to have a significant beneficial impact on release risk.

flow to faulted flow, eliminateconseqential feed OF 86 1.K >$0K SNotsepeeos cost beneficial based on assumed ex lo oofsigiiateloereensi elimination of alligebnificnly t peed oesseaassociated risk with loss ofsor power. PRA case NOLOSP assumes elimination ofael

3 Loss of Mffite LOSP events and provides a conservative benefit for ZZ.SY2.FX, which Power subsequent #13, #156,4#160 NOLOSP $704K $1.34M >$2M models consequential loss of offsite power followin a LOCA event. The 7-Z.SY2.FX to IOCA initiator cost ofpower system upgrades that would significantly reduce or eliminate consequential loss of lst power events is expected to significantly exceed the conservative benefit Not cost beneficial based on assumed elimination of all risk associated with the startup feedwater pump hardware. A hardware change to improve SUFP system reliability, e.g.. install a parallel valve, is expected to significantly exceed the conservative benefit. PRA Case SUFPS is used to conservatively estimate the SAMA benefit This case is SUFP to EFW Improve reliability of SUFP, conservative because it assumes guaranteed success of the entire Startup

4 Header MOV FW- pFeedotersystem. Basic event FWV156.FC contributes approximately eliminate potential for SUFP SUFPS >$100K FWV156.FC V-156 fails to open failures sg $ -- 23% to the total unreliability of the SUFP system. Therefore, the on demand maximum benefit associated with reliability improvements to valve FW-V-156 is approximately 23% ofthe SUFPS PRA case results. Thus, the adjusted benefits are:

Nominal Benefit: $89K

0.23 = $20.5K Upper Bound Benefit $170K

0.23 = $39.1K 29 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A Baýcvetslarejro ;SeabrookR,*ne oAI.I jli'.1iL .. p;~i~:;i A,cie '... :" . . . . . . . ..

I ... 'RA.JaB i efi?- t ":"ud**,:d i Co' [".

1;nei

.at, E rl~ t E valua Not cost beneficial based on assumed elimination of all risk associated with the startup feedwater pump hardware. A hardware change to improve SUFP system reliability, e.g., install a parallel valve, is expected to significantly exceed the conservative benefit PRA Case SUFPS is used to conservatively estimate the SAMA benefit. This ease is SUHe to EFW Improve reliability of SUFP, conservative because it assumes guaranteed success of the entire Startup

5Header MOV FW- elaiiyofSF50.5K $2rv 539.1K Fed trsytmBsievtFW1.Fasoon'ts eliminate potential for SUFP SUFPS >$100K eedwater system. Basic event FWV163.FC also contributes FWV163.FC V-163 aos to open failures 59K $14-70K approximately 23% to the total unreliability of the SUFP system.

on demand Therefore, the maximum benefit associated with reliability improvements to valve FW-V-163 is approximately 23% of the SUFPS PRA case results.

Thus, the adjusted benefits are:

Nominal Benefit $89K

0.23 = $20.5K Upper Bound Benefit: S170K

0.23 =39.1K Not cost beneficial based on assumed elimination of all risk associated with MD EFW pump failures. A hardware change to reduce/eliminate mechanical failures of the motor-driven EFW pump is expected to EFW motor-driven Hardware change to eliminate significantly exceed the conservative benefit.

6 pump FW-P-37-B or reduce mechanical failures of MEFWS $81K $154.1K >$200K SAMA 25,26 and 28 evaluated installation of a similar redundant pump, FWP37B.FS fails to start on MD EFW pump (installation of 410 this improvement was previously estimated at greater than $2 million demand additional motor-driven pump) dollars in the Pilgrim License Renewal application. In the Duane Arnold License Renewal application, the Pilgrim estimate was judged to be low and used a $20 million estimate based on similar modification experience.

Operator action for Not cost beneficial based on assumed elimination of the human failure risk SI termination given including actions OTSI3, OTSI4 and OTS15 for SI termination during successful Implement hardware change to SGTR. A hardware change to improve reliability of SGTR control is

7 cooldown and improve reliability of SGTR OTSIS $59.4K $113K >$300K expected to significantly exceed the conservative benefit HH.OTSI3.FA depressurization for control eliminate or reduce -410K Design changes to implement this type of action would be similar in nature SGTR. operator failure to terminate SI to SAMAs 147, 174, 186 and 187, which were estimated to exceed 5500K. As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

Not cost beneficial. PRA case TDAFW conservatively assumes Turbine Driven guaranteed success of the turbine-driven EFW pump. Thus, the benefit of

8 Pump TRBINE installing an additional turbine-driven pump is conservatively high.

FWP37A.FSP 3p f210K falt #163 TDAFW $399K >$2M Installation of an additional turbine-driven EFW pump is not practical and start on demand the cost would be expected to significantly exceed the conservative benefit The reduction in seismic risk would not be significant unless the new equipment is also seismically rugged, which would further increase 30 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A Eialiipperýiifpli

-iil Y~~i Nominal; Ro, n U: i I. . Ii Ascate.d SAl s). -PpkIqis i2.n~j1X; l '2.lx JE: iv:

i...!.. . . .. . . . . . . ; ".

4 -+ -I-. 4.

cost.

+ 4 + 4 Not cost beneficial based on assumed elimination of the human failure risk. A hardware change to improve reliability of ECC control is expected Operator minimizes to significantly exceed the conservative benefit ECCS flow Implement hardware change for

9 automatic ECC control, >$300K Design changes to implement this type of action would be similar in nature w/reeirculation ORWS $66.8K $1273K HI-lORWMZI. failure eliminate or reduce operator to SAMAs 147. 174, 186 and 187. which were estimated to exceed failure to min- ECC flow $500K. As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

ATWS -

Unfavorable

100 .rE ) PrTime Exposure b abi i ty . pImprove ro ced u rehardware s to red u cand e or Not cost beneficial based on assumed elimination of UET basic event o6.3K eliminate unfavorable exposure UET $12.6I >$50K RRW LEI. LIA probability contribution. A hardware or procedure change to improve CRI availability is expected to significantly exceed the ZZgPORV.NOCRI ivenavailable, SVs 2 PORVsw/o &3 availability improve CRI probability. conservative benefit.

Control rod insertion (CRI)

Operator fails to Not cost beneficial based on assumed elimination of all risk associated

. P. istart SUei? given S Pror e$3.K ofedtor 27SUFP, with manual action to start the SUFP. A hardware change to provide an initiator eliminate potential for operator OSPFPS $13.9K $26.7K >$100K auto-start feature to the startup feedwater pump is expected to significantly failure to start SUFP] exceed the conservative benefit.

Not cost beneficial based on assumed elimination of all risk associated with the startup feedwater pump hardware. A hardware change to improve SUFP reliability is expected to significantly exceed the conservative benefit. PRA Case SUFPS is used to conservatively estimate the SAMA benefit. This case is conservative because it assumes

12 Startup Feed Pump Improve SUFP reliability, S20.5K $39.1K uauranteed success of the entire Startup Feedwater system. The startup FW-P 113 fails to eliminate potential for SUFP SUFPS >$100K feed purmip itself contributes approximately 15% to the total unreliability of FWP113.FS start on demand mechanical failures $SW S the SUFP system. Therefore, the maximum benefit associated with reliability improvements to the startup feed pump is approximately 15% of the SUFPS PRA case results. Thus. the adjusted benefits are:

Nominal Benefit. $89K

0.15 = $13.3K Upper Bound Benefit $170K

0.15 = $25.5K 31 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A Trtidle!Xl5s Ii ,i*.. I'broo*Station Sesit*:viuto~fTp*a~ v ns ConnfriIu6ng to !R(*-!fl'uslng Seismi Rts~l*]flltiherof [-i' !! 2*.:.I*.;I!!: ii:i. 11.pi.i:.

i*:i:[I].--,1j1! i: 11!

Bi a . I , .I ...iD1 s -I . I,,,. B a ,1... .. .. . :. .: I i:. i ' i; : .2 ! J1i. .A H1D i P1. I II , J I,1- -_ _ _ , t;. . 1 ,

............. ... .. *.-*.............................i.t .*,,. *****'******I*] 1I.wI: 1LItr IIKW Not cost beneficial based on assumed elimination of all risk associated with MD EFW pump fa'iures. A hardware change to reduce/eliminate mechanical failures of the motor-driven EFW pump is excpected to Hardware change to improve significantly exceed the conse-rvatie benefit.

3EFW motor-driven pump reliability, eliminate or >$200K SAMA 25, 26 and 28 evaluated installation of a similar redundant pump, pump FW-P-37-8 reduce mechanical failures of MEFWS " 80.91K S154.1K thils improvement was previously estimated at greater than $'2 million FWP37B.FR fails to run MD EFW pump (installation of >$OO dollars in the Pilgrim License Renewal application. In the Duane Arnold additional motor-driven pump) LiUcense Renewal application, the Pilgrim estimate was judged to be low and used a $20 million estimate based on similar modification experience.

Not cost beneficial based on assumed elimination of all risk associated with the startup feedwater pump hardware. A hardware change to improve SUFP reliability is expected to significantly exceed the consrative benefit. PRA Case SUFPS is used to conservatively estimamte he SAMA benefit. This case is conservative because it assumes

1-SFW-rPCVrcuati6 Hardwrelihabilityo eiminateo JO S1.guaranteed success of the entire Startup Feedwater system. The SUFP

W 1 4 32.C fiS to openicuton SUPredueptniaily flmnaeor S$P/&vcOKP $13 >$100K recirculation valve FW-PCV-4326 contributes approximately 9.0%, to the FWP373,FRfail FWPC432.FC o to rnt opn ump fo MDEFW fais reucepotntia (nstalatin SUP~ave ofdolrsivn UFP $g/4 t-7A/4total EF Pilgmim unreliabilityupof theLiesbenewal hrfrthe SUFP system. Therefore, the associatinInt DuneArol maximumed benefit demand failures associated with reliability improvements to valve FW-PCV-4326 is approximately 9.0% of the SUFPS PRA case results. Thus, the adjusted benefits are:

Nominal Benefit $89K

0.09 = $8.0K SD _ Upper Bound Benefit: $ 70K*0.09= $ 5.3K Not cost beneficial based on assumed elimination of all risk associated with MD EFW pump failures. A hardware change to reduce/eliminate mechanical failures ofthe motor-driven EFW pump/valves is expected to Hardwar c e tsignificantly exceed the conservative benefit. Valve FW-V-347 FWP3BHardware me chanical reaue failuresto of change improve MD rEFWS $S. reliability approximatelyto8.5%

contributesimprovements valvetoFW-V-347 the total unreliability of the 8.5%

is approximately motor-of the

1!5 FW-V-37MOV recirculation K 3 45 pump/valves addioeniow EFW MEFWS PRA case results. Thus, the adjusted benefits are:

Nominal Benefitc basK

0.085 e oc7.6K Upper Bound Benefit $170K

0.085 = $14.5K 32 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A rok Sustii~ ~'i~i of'top Biia v oRcSi

'heCnrbtn sngSsmt Rak ultiplier pfF.;.I. i h]I]Iii'I C ris; 0 AI:1

.11 ij II I I

l. *j1:111i:

: 1:*..

" E: I I Ii **I*i. I I'*I.,., *, II I II i

I Boirnd I i t !':!*

on i ;i! Assocatted SAMA. PRA.

i Case:i Benefit at 'Bcnefit 1.1~~.::i l'::: I I 1111 at .Estunat~ ii .. .1 J1 A1 SI II. I 2Ax III Not cost beneficial based on assumed elimination of the human failure risk Operator action for including actions OTSB, OTSI4 and OTSIS for SI termination during SI termination given SGTR. A hardware change to improve reliability of SGTR control is

successful cooldown Provide HHOS.A and depressurization eliminateautomatic or reducecontroL operator OTSIS $59.4K $113K >$300K expected to significantly exceed the conservative benefit HH.OTSI3.FArS failure to tereuinate So SS300K Design changes to implement this type of action would be similar in nature for SGTR f eto SAMAs 147, 174, 186 and 187, which were estimated to exceed

$500K. As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

Not cost beneficial based on assumed elimination of the human failure Operator minimizes risk. A hardware change to improve reliability of ECC control is expected ECCS flow Implement hardware change for to significantly exceed the conservative benefit.

2 w/recirculation automatic ECC control, >$300K HH.ORWMZ1.FA failure eliminate or reduce operator ORWS 66.8K 127.3K -$00K Design changes to implement this type of action would be similar in nature failure'to min. ECC flow to SAMAs 147, 174, 186 and 187, which were estimated to exceed

$500K. As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

Not cost beneficial based on assumed elimination of all risk associated with loss ofoffsite power. PRA case NOLOSP assumes elimination of all 43 Loss of Offsite LOSP events and provides a conservative benefit for ZZ.SY2.FX, which Power subsequent to #13, #156, #160 NOLOSP $704K $1.34M. >$2M models consequential loss of'offsite power following a LOCA event The ZZ.SY2.FX LOCA initiator cost of power system upgrades that would significantly reduce or eliminate consequential loss of offsite power events is expected to significantly exceed the conservative benefit OTSIS is representative case for HK.ODDSGI.FA. Not cost beneficial based on assumed elimination of the human action to diagnose SGTR Operator fails to event. A hardware change to improve reliability of SGTR control is

4 diagnose SG Tube Implement hardware change to >$300K expected to significantly exceed the conservative benefit HH-.ODDSGLFA Rupture Event eliminate or reduce operator OTSIS $59.4K $ 113K failure to terminate SI >$109K Design changes to implement this typ of action would be similar in nature to SAMAs 147, 174, 186 and 187, which were estinmated to exceed

$500K. As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

Operator Implement hardware change to Not cost beneficial based on assumed elimination of operator action to

5 depressurizes RCS improve reliability of SGTR S $ $ depressurize RCS. A hardware change to improve reliability of SGTR HH.OSGRDI.FA to Stop Break Flow control eliminate operator OSGRDS . control including depressurization is expected to significantly exceed the to Ruptured SG action to depressurize conservative benefit.

____________(SGTR) cnevtv eei 33 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A Not cost beneficial based on assumed elimination of operator action to Implement hardware change to cooldown and depressurize RCS. A hardware change to improve improve reliability, eliminate ORWCDS $9.3K reliability of VSEQ control including depressurization is expected to operator action to depressurize significantly exceed the conservative benefit Not cost beneficial. PRA case TDAFW conservatively assumes guaranteed success of the turbine-driven EFW pump. Thus, the benefit of installing an additional turbine-driven pump to improve reliability is

7 conservatively high. Installation of an additional turbine-driven EFW

163 FWP37A.FR pump is not practical and the cost would be expected to significantly exceed the conservative benefit. The reduction in seismic risk would not be significant unless the new equipment is also seismically rugged, which would further increase cost.

ORWS is representative case for HHORWIN 1.FA. Not cost beneficial based on assumed elimination of the human action to perform RWST Operator fails to makeup. A hardware change to improve reliability of RWST makeup initiate makeup to Hardware change to provide (automatic control system) is expected to significantly exceed the

8 RWST given LOCA >$300K w/ recirculation auto-makeup to RWST, conservative benefit HH.ORWIN I.FA eliminate operator action >$IOOK failure Design changes to implement this type of action would be similar in nature to SAMAs 147, 174, 186 and 187, which were estimated to exceed

$500K. As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

4 +

OSGRDS is representative case for HH.OTEF3.FA. Not cost beneficial based on assumed elimination of operator action to terminate EFW flow Operator fails to for SGTR, A hardware change to improve reliability of SGTR control terminate EFW flow including control of EFW to the ruptured SG is expected to significantly

9 Hardware change to eliminate >S300K to ruptured SG - OSGRDS S9.5K $17.9K exceed the conservative benefit.

HH.OTEFW3.FA SGTR operator action to depressurize Design changes to implement this type of action would be similar in nature to SAMAs 147, 174, 186 and 187, which were estimated to exceed

$500K. As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

34 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A ivt6Ealiat2oii o4'f' 1Basic kEýiets 16'triutiln oRCSI.... inýS-,I,ri.d hi'...2l1..

I I'

" Rii*s ' i

. . III:!.. ! Il PIRA INominal, IJI B'eefit, atl Cst]ML

-Estnnatc:i:*

22x 'i>i:*:,:

2. I I,'

C *. I. =

1*

ORWS is representative case for HH.ORWLTF:*. Not cost beneficial based on assumed elimination of the human failure risk A hardware Operator fails to Hardware change for automatic change to improve reliability of RWST makeup (automatic control system) maintain stable plant

10 control or eliminate operator >$300K is expected to significantly exceed the conservative benefit conditions w/ long ORWS $66.8K $1273K HI-LORWLT1.FA term makeup action to maintain stable Design changes to implement this type of action would be similar in nature conditions to SAMAs 147, 174, 186 and 197, which were estimated to exceed

$500Y. As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

OSGRDS is representative case for HH.OSGRC1.FA. Not cost beneficial Operator fails to based on assumed elimination of operator action to cooldown RCS. A cooldown RCS to hardware change to improve reliability of SGTR control including RCS

11 allow isolation of Hardware change for automatic >$300K cooldown is expected to significantly exceed the conservative benefit control or eliminate operator OSGRDS $9.5K $17.9K HH.OSGRCI.FA ruptured SG (SGTR) action to cooldown RCS :-S4004K Design changes to implement this type of action would be similar in nature to SAMAs 147,174. l6 and 187, which wereestimated to exceed

$500K. As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

Operator fails to cool/depressurize Rcoere - D awr ag rao tiNot cost beneficial based on assumed elimination of all ORHCD related

12 RCS for RHR S oD Hardware change for automatic operator actions to cooldown RCS. A hardware change to improve HH.ORHCD.FA cooling for SGTR control or eliminate operator QRHCDS 525.8K 49.4K >S100K reliability of SGTR control including RCS cooldown is expected to OSMRD significantly exceed the conservative benefit Containment Building Spray Hardware change to improve Not cost beneficial based on assumed elimination of both CBS-V-11 and

3Pump P-9B valer~eliblteiiaeCS CSV <K $K >10 CBS-V-17 failure to open on demand. A hardware change to improve CSV7.FC discharge MOV valve reliability, eliminate CBS CBSDVS <2K <2K >$100K reliability of CBS discharge valves is expected to significantly exceed the CBS-V-17 fail to conservative benefit.

open on demand 35 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A i I I

36 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A 37 of 55

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure /Attachment A lii uainOf n~i To l IC si'E~tt k VC ont4 MA~tingý to RC- L44]';: Ul NominJ

" al""

T I 1*1 1.1.1 Be.ne.f]

k:it!i ,i:

AM AH. PR~4'Case~ at2mn..x Not cost beneficial. PRA case E6S is representative of 4Kv Bus E5. The PRA case conservatively assumes elimination of Bus E5 faults that could cause an initiating event (IEmodel) and/or fail the associated power division during mission time (support system model) by assuming guaranteed success of the bus. It is noted that due to their relatively passive design.

4kV buses are relatively reliable and have a low failure rate. A hardware

5 Improve Bus E5 reliability. >$500K change that would significantly improve bus reliability, for example adding eliminate all potential for bus E6S $82K S 156K a redundant bus within a division, is judged impractical and is expected to XY(EDESWG5.FX fault ~4100K significantly exceed the conservative benefit Implementation assumed to involve design of additional bus to achieve improvement in bus reliability with a cost of>$1M. This scope is assumed similar to SAMA #16 (improved uninterruptible power supplies). As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

Not cost beneficial. PRA case NOSBO conservatively assumes elimination of all station blackout events by assuming guaranteed success of onsite diesel generators. Thus, the benefit of modifying the onsite electrical power

9, # 10, #14, #155 NOSBO $326K S620K >SIM system to add or modify a DG to improve/eliminate DG failures is conservatively high. The cost of installing an additional DG to improve electrical system reliability is expected to significantly exceed the conservative benefit Not cost beneficial. The PRA case conservatively assumes elimination of Bus E6 faults that could cause an initiating event (IE model) and/or fail the associated power division during mission time (support system model) by assuming guaranteed success of the bus. It is noted that due to their relatively passive design, 4kV buses are relatively reliable and have a low Improve Bus E6 reliability, >$500K failure rate. A hardware change that would significantly improve bus

7 eliminate all potential for bus E6S $82K S156K reliability, for example adding a redundant bus within a division, is judged XX.EDESWG6.PX fault >$100 impractical and is expected to significantly exceed the conservative benefit.

Implementation assumed to involve design of additional bus to achieve improvement in bus reliability with a cost of>VIM. This scope is assumed similar to SAMA #16 (improved uninterruptible power supplies). As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

38 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A uationfof Toip Basic Th'ents Con~tribting to RC-L 414

'i Not cost beneficial based on assumed elimination of all risk associated with loss of offsite power. PRA case NOLOSP assumes elimination of all LOSP events and provides a conservative benefit for ZZ._SY 1.FX, which models NOLOSP $704K $1.34M >S2M consequential loss of offsite power following a plant trip event The cost of power system upgrades that would significantly reduce or eliminate consequential loss of offsite power events is expected to significantly exceed the conservative benefit

1* *1*

Not cost beneficial. The PRA case conservatively assumes elimination of Bus E6 faults that could cause an initiating event (IE model) and/or fail the associated power division during mission time (support system model) by assuming guaranteed success of the bus. It is noted that due to their relatively passive design, 4kV buses are relatively reliable and have a low

.Improve Bus E6 reliability, failure rate. A hardware change that would significantly improve bus

-#9 45100K 4KV BUS E6 fault eliminate all potential for bus E,6S $82K $156K reliability, for example adding a redundant bus within a division, is judged EDESWG6.FX fault impractical and is expected to significantly exceed the conservative benefit Implementation assumed to involve design of additional bus to achieve improvement in bus reliability with a cost of >$1M. This scope is assumed similar to SAMA #16 (improved uninterruptible power supplies). As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

Not cost beneficial. PRA case SEPES conservatively assumes elimination of all SEPS DG hardware failures (assumes guaranteed success of SEPS

9. #14, #189, Improve DGs). Thus, the benefit of modifying the SEPS electrical power system to

10 l-SEPS-Do A reliability of SEPS DO, add or modify a DG to improve/eliminate DG failures is conservatively high. The cost to analyze existing SEPS DGs or installation of an additional SEPSDG2XFR3 fi touru 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months failure potential for SEPS eliminate DG to improve electrical system reliability is expected to significantly exceed the conservative benefit Not cost beneficial. PRA case SEPES conservatively assumes elimination of all SEPS DO hardware failures (assumes guaranteed success of SEPS

11 I-SEPS-DG-2-B #9, #14, Improve reliability of DGs). Thus, the benefit of modifying the SEPS electrical power system to fails to run within SEPS DG, eliminate potential SEPES $83.6K $159.2K >$300K add or modify a DG to improve/eliminate DG failures is conservatively SEPSDG2B.FR3 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months for SEPS failure high. The cost to analyze existing SEPS DGs or installation of an additional DG to improve electrical system reliability is expected to significantly exceed the conservative benefit.

39 of 55

United States Nuclear Regulatory Commission SBK-L-I 1067 / Enclosure /Attachment A ic ~Ris 1 Mltipi~il Ii? . I::: :lr! i i

"- " " .-."'. : ; I: ,.i: I ...

Evaluation -. , 1 "

iI.

Not cost beneficial based on assumed elimination of all risk associated with TE-2171 and TE-2271 failures. PRA case PCCTS conservatively assumes guaranteed success of the iE function for PCC Trains A and B that could cause an initiating event (IE model) and/or fail PCCW during mission time PCC Train B (support system model). Hardware changes that would significantly

12 Temperature Improve PCC TE reliability, improve temperature control reliability, for example adding additional Element CC-TE- eliminate potential for temp. redundant instnraentation and controls, is expected to significantly exceed cCCrE2271 .FZ 2271 transmits false element failure the conservative benefit.

low Design changes to implement this type of action would be sirmilar in nature to SAMAS 147, 174, 186 and 187, which were estimated to exceed $500K, As this value substantially exceeds the upper bound benefit no more refined estimate is warranted..

Not cost beneficial based on assumed elimination of all risk associated with TE-2171 and TE-2271 failures. PRA case PCCrS conservatively assumes guaranteed success of the TE function for PCC Trains A and B that could PCC Train A cause an initiating event (IE model) and/or fail PCCW during mission time Temperature (support system model). Hardware changes that would significantly

13 Element'CC-TE- Improve PCC TE reliability, >$250K improve temperature control reliability, for example adding additional CCTE2171.FZ 2171 traiismits false eliminate potential for temp. u"'Wog redundant instrumentation and controls, is expected to significantly exceed low element failure I the conservative benefit.

Design changes to implement this type of action would be similar in nature to SAMAs 147, 174, 186 and 187. which were estimated to exceed S500K.

As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

Operator fails to start containment Hardware change for automatic Not cost beneficial based on assumed elimination of all operator actions to

14 injection-early without AC power initiation of containment initiate containment injection (XOINE1. XOINE2. & OINE3). A hardware

-H.OINF3.FA (gravity drain of injection gravity drain, change to improve containment injection reliability is expected to RWST) eliminate operator action significantly exceed the conservative benefit 40 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A 41 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A 42 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A jI'ablX 7' S rbkgiiýS e~fiiyEaut~i of Cotitt1kt R;sn ~si ~~utpi*

ý15v~~~ntsar~~firbf'ebO one toiiI5" I H idli., iWJ-ýj

~ Ii Ass...iate. I.4: '-Upper,']

Aissociate'd SA Nominali k v :.: *!i Cost~'

BasicEveat I IDesciptzOu PR ast Benefitait I, E~timatc

: : -:

. :.* . .:

. I I.. .I

'Iii .:. .. . : . . . "j:1 . .. 1 Not cost beneficial based on assumed elimination of all risk associated with loss ofoffsite power. PRA case NOLOSP assumes elimination of all LOSP

5 Loss of Offsite events and provides a conservative benefit for ZZ.SY1.FX, which models Power subsequent #13, #156, #160 NOLOSP $704K $1.34M >$2M consequential loss ofoffsite power following a plant trip event. The cost of ZZ.SYI.FX to plant trip power system upgrades that would significantly reduce or eliminate consequential loss ofoffsite power events is expected to significantly exceed the conservative benefit.

Not cost beneficial based on assumed elimination of all risk associated with loss of offsite power. PRA case NOLOSP assumes elimination of all LOSP

6 Loss of Offsite events and provides a conservative benefit for ZZ.SY2.FX, which models Power subsequent #13. #156, #160 NOLOSP 8704K $1.34M >$2M consequential loss of offsite power following a LOCA event The cost of ZZ.SY2.FX to LOCA initiator power system upgrades that would significantly reduce or eliminate consequential loss of offsite power events is expected to significantly exceed the conservative benefit.

Not cost beneficial. PRA case TDAFW conservatively assumes guaranteed Turbine Driven success of the turbine-driven EFW pump. Thus, the benefit of installing an

7 Pump T additional turbine-driven pump is conservatively high. Installation of an F#P37A.FS1 FW-P-37A fails to #163 TDAFW $210K $399K >$2M additional turbine-driven EFW pump is not practical and the cost would be start on demand expected to significantly exceed the conservative benefit The reduction in seismic risk would not be significant unless the new equipment is also seismically rugged, which would further increase cost.

Not cost beneficial. PRA case SEPES conservatively assumes elimination of all SEPS DO hardware failures (assumes guaranteed success of SEPS 1-SEPS-DG-2-A fails to run within #9, #14, #189, Improve DGs). Thus, the benefit of modifying the SEPS electrical power system to

8 toSran-wit2iA reliability ptnilSEPES of SEPS DG, 83.6K $159.2K >8300K add or modify a DG to improve/eliminate DG failures is conservatively eliminate potential for SEPS high. The cost to analyze existing SEPS DGs or installation of an hours failure additional DG to improve electrical system reliability is expected to significantly exceed the conservative benefit.

Not cost beneficial. PRA case SEPES conservatively assumes elimination of all SEPS DO hardware failures (assumes guaranteed success of SEPS

9, #14. #189, Improve DGs). Thus, the benefit of modifying the SEPS electrical power system to SEPSDG2B reliability of SEPS DG, add or modify a DG to improve/eliminate DO failures is conservatively SEPSDG2B.FR3 sto rn within reliminate potential for SEPS SEPES 83.6K 159.2K >300K high. The cost to analyze existing SEPS DGs or installation of an Srfailure additional DO to improve electrical system reliability is expected to significantly exceed the conservative benefit.

43 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A

. .

ii. I

. . .

'~t Iii

.. . ..

!~~iI:I!:L!iI~!

. . .. . .

~

. . . . . . . .. .. . .... . . ..

I' I II . i + . .

lat-2.1x ii .1. 'IIW Nstime Evaluai on' , II I .iji..

j iIJ I Not cost beneficial. The PRA case OSEPALL conservatively assumes guaranteed success of all manual actions to align and load the SEPS diesel generators. The current design requires the operator to manually align

10 OPERATOR fails SEPS to the desired bus and to manually load SEPS to ensure power is

9. #14, #154, Provide auto-to close SEPS >S750K I available to needed components. The proposed SAMA is to install a HH.OSEPI .FA start and load for SEPS DG breaker from MCB control system to perform these actions automatically. The cost of the automatic control system is estimated to exceed the benefit. PRA case OSEPALL models elimination of all SEPS operator actions and is used here for operator action HH.OSEP1.FA in place of PRA case OSEPI.

Not cost beneficial. PRA ease LOCA04 conservatively assumes guaranteed success of the RWST volume as a continuous source of water for ECCS.

Included in this conservative PRA case is the assumption that all operator OPERATOR fails to align ECCS for actions for the various high and low pressure seequences and hardware to Provide hardware change for

11 HP Cold Leg automatic alignment of initiate the ECCS swap-over to the sump are successful Therefore, the LOCA04 benefit of an automatic swap-over control system is conservatively high.

HH.OHPR3.FA Recirculation for recirculation. eliminate operator The cost of implementing a swap-over control system is expected to Feed & Bleed action significantly exceed the conservative benefit The implementation cost is Cooling with CBS consistent with the implementation cost estimated for other plants, for example Indian Point and MecGuire estimated >$1M and Diablo Canyon estimated >$6M.

12 PORV RC-PCV- Improve reliability of PORV Not cost beneficial based on assumed elimination of all PORV reclose reseat functiont,ailure eliminate failure potential. A hardware change to improve reseat reliability is 456B fails to reseat reseat f RCPCV456B.RS PORV re-seat failure expected to significantly exceed the conservative benefit Not cost beneficial. PRA case E6S is representative of 4Kv Bus ES. The PRA case conservatively assumes elimination of Bus E5 faults that could cause an initiating event (iE model) and/or fail the associated power division during mission time (support system model) by assuming guaranteed success of the bus. It is noted that due to their relatively passive design, 4kV buses are relatively reliable and have a low failure rate. A

13 Improve Bus E5 reliability, hardware change that would significantly improve bus reliability, for 4KV BUS E5 fault eliminate / reduce potential for example adding a redundant bus within a division, is judged impractical and EDESWG5.FX bus fault is expected to significantly exceed the conservative benefit.

Implementation assumed to involve design of additional bus to achieve improvement in bus reliability with a cost of>$1M. This scope is assumed similar to SAMA #16 (improved unintenuptible power supplies). As this value substantially exceeds the upper bound benefit no more refined estimate is warranted.

44 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A 45 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A

IT'i Wkig%;:i ;1111il. sa bro.o k Stati 0 i ns va qat!qp 9 . eismic! s !M !: !i ý-!'ý i ý: I' H W, Iljýý1V AI ~ 1 IIII1IiIIIIIIIIIIII;.II ji IiiI fl knI!

ni~III I arook~oIer;ngiiaLianK AI'HI 1IIl I II, a ) Ii

'

i

.~ I~j.:;

... j EvIito to Si sm i II'.. IT Salem.SItatioia P'iopoged SAfA CaTdteI, III Enhance Procedures and Screened Phase 1, Criterion B - Intent Met.

Provide Additional Seabrook currently has a specific abnormal procedure for implementing compensatory SAMA intent is met, therefore SAMA evaluation not sensitive to seismic SAMA #1 Equipment to Respond to actions for loss of control room ventilation or air conditioning A compensatory procedure risk increase. No impact on SAMA evaluation.

Loss of Control Area for loss of Essential Switchgear Room ventilation also exists (as addressed in Seabrook Ventilation. SAMA #82).

Screened Phase 2, Not Cost-Beneficial.

Re-configure Salem 3 to Seabrook Station is a single unit site with no other onsite power generation capability Seabrook SAMAs # 13, #14 and #156 have been evaluated for sensitivity to Refer SAMA #2 Provide Backup aAC More Expedient Power Source (exceptpower onsite for onsite emergency generation capability was evaluateddiesel and supplemental generators).

in Seabrook SAMA Installation of additional

13 (buried oflsite seismic X-2.increase and have been shown not to be cost beneficial.

to Table risk for Salem I and 2. power source), SAMA # 14 (gas turbine), and SAMA #156 (install alternate offsite power source). These SAMA candidates were judged not cost-beneficial in Phase 2.

Screened Phase I. Criterion A - Not Applicable.

Install Limited EDG Cross- Seabrook Station is a single unit site with no other onsite power generation capability SAMA not applicable, therefore SAMA evaluation not sensitive to seismic SAMA #3 tie Capability Between Salem (except for onsite emergency and supplemental diesel generators). Phase I screening is risk increase. No impact on SAMA evaluation.

I and 2. consistent with Seabrook SAMA# 12, Create AC Cross-de Capability with Other Unit (multi-unit site).

Screened Phase 1, Criterion B - Intent Met.

Install Fuel Oil Transfer Pump on -C' FDG & This SAMA is similar to Seabrook SAMA # I1 and SAMA #17. Seabrook currently has 2 SAMA #4 Provide Procedural Guidance EDCs that are dedicated to their respective emergency bus. In addition, Seabrook has a SAMA intent is met, therefore SAMA evaluation not sensitive to seismic for Using -C- EDG to Power third diesel generator unit - supplemental emergency power supply (SEPS), which can be risk increase. No impact on SAMA evaluation.

Selected "A" and "B- Loads. aligned to either emergency power division. In addition, Seabrook has the capability to cross-tie the divisional EDG fuel oil tarks.

46 of 55

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure /Attachment A tjiI Ta~~-8 Sa~l I I ttinestiiyvau~d ~'t P~~S her I p IjKl.I~'I!I~

,...II.I,'.~.i "

(~~~~~ther~~~~~~ K AiiS~~i'I Pl1~t,~Tl)'II Rs~li

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SAi

t6ý !11: ._ ici I .;: Iý I` I e l .t cik PDP Replacement - Screened Phase 2, Not Cost-Beneficial Replacement of PDP and installing a diesel generator for motive power is similar to PDP Replacement - Seabrook SAMA #26 has been evaluated for sensitivity Seabrook SAMA #26 (install additional high pressure injection pump with independent to seismic risk increase and shown not to be cost beneficial. Refer to Table diesel). This SAMA was shown to be not cost-beneficial. X-2.

Portable Battery Charger - Not screened - Potentially Cost-Beneficial - however, similar to Seabrook SAMA #157 Portable Battery Charger - Seabrook SAMA # 157 (provide independent AC Install Portable Diesel Installing portable diesel generator for charging batteries is similar to Seabrook SAMA power source for battery chargers) has been evaluated for sensitivity to Generators to Charge Station #157 (provide independent AC power source for battery chargers). ThisSAMAwa seismic risk increase. This SAMA is potentially cost beneficial. Referto SAMA #5 Battery and Circulating shown to be potential cost beneficial to extend main station battery life during long term Table X-2.

Water Batteries & Replace SBO sequences.

PDP with Air-Cooled Pump.

Regarding switchyard DC cont-ol power, Seabrook has an 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months switchyard battery system, independent of the main station batteries. If switchyard batteries become depleted, Seabrook switchyard breakers can be operated locally/manually without DC control power. Switehyaard Do Control Power - SAMA intent is met, therefore SAMA This local/manual action is accounted for in the PRA by assuming an additional hour is evaluation.

needed to recover offsite power during long term SBO sequences. Removal of the additional hour for local action is judged to have a negligible positive impact on SBO core damage risk.

Not screened - Potentially Cost-Beneficial - however, similar to Seabrook SAMA # 157 Portable Battery Charger- Seabrook SAMA # 157 (provide independent AC Installing portable diesel generator for charging batteries is similar to Seabrook SAMA power source for battery chargers) has been evaluated for sensitivity to

157 (provide independent AC power source for battery chargers). This SAMA was seismic risk increase. This SAMA is potentially cost beneficial. Refer to shown to be potential cost beneficial to extend main station battery life during long term Table X-2.

Install Portable Diesel SBO sequences.

SAMA Generators to Charge Station Regarding switchyard DC control power, Seabrook has an 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months switchyard battery

5A Battery and Circulating system, independent of the main station batteries. If switchyard batteries become depleted.

Water Batteries. Seabrook switchyard breakers can be operated locally/manually without DC control power. Switchyard DC Control Power - SAMA intent is met, therefore SAMA This local/manual action is accounted for in the PRA by assuming an additional hour is evaluation not sensitive to seismic risk increase. No impact on SAMA needed to recover offsite power during long term SBO sequences. Removal of the evaluation.

additional hour for local action is judged to have a negligible positive impact on SBO core damage risk.

Enhance Flood Detection for Screened Phase 1, Criterion B - Intent Met.

84' Aux Building and SAMA #6 Enhance Procedural Flood alarms, sump alarms, response procedures and associated operator actions were SAMA intent is met, therefore SAMA evaluation not sensitive to seismic Guidance for Responding to reviewed as part of updated internal flooding assessment. Current alarm response risk increase. No impact on SAMA evaluation.

Service Water Flooding. procedures judged adequate and are reflected in assessment.

47 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A d

-,ýbr"kl tation! 11.8 .

ernitiVit" E .i . f.iNheý kiantý' §ýýlTýas lsm!c'iý 4 X"Ire Iromi S j-SAM

!:MA 1 :D ptionI :ijj I:::;: 'I i :IIi~~~

SeabroonalEvaluat F R I:iSk .... ....,Senstiwty I' dI iai. .I.:F!~ FI !

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Screened Phase 2, Not Cost-Beneficial This SAMA involving long term makeup to the CST is similar to Seabrook SAMA #162 (increase capacity ofthe CST) and SAMA #164 (modify 10- condensate filter flange to have 2-112-inch female fire hose adapter with isolation valve). These SAMAs were shown Install -B" Train AFWST to be not cost-beneficial. In addition, it is noted that the time to empty the CST is Seabrook SAMAs #162 and #164 have been evaluated for sensitivity to SAMA #7 Makeup Including Alternate approximately 17 hours1.967593e-4 days 0.00472 hours 2.810847e-5 weeks 6.4685e-6 months . Seabrook currently has several means ofmaking-up water seismic risk increase and have been shown not to be cost beneficial. Refer Water Source. inventory to the CST. These include alignment of the Demineralized Water (DW) system to Table X-2.

pumps or alignment of the gravity drain of the Demineralized Water Storage Tanks to the CST, makeup from the condenser hot well spill or by use of the cooling tower portable pump. Therefore, the intent of the Salem SAMA is judged to be met regardless of cost-benefit Screened Phase 1, Criterion B - Intent Met.

Install High Pressure Pump This SAMA is similar to Seabrook SAMA #66 and SAMA #75. Seabrook currently has Powered with Portable Diesel the capability to connect several water sources to supply the EFW suction header. These SAMA intent is met, therefore SAMA evaluation not sensitive to seismic SAMA #8 Generator and Long-term include: the fire system using a diesel-driven fire pump- the portable diesel-driven pump risk increase. No impact on SAMA evaluation.

Suction Source to Supply the with suction connected to the fire main and the cooling tower portable makeup pump using AFW Header. either the cooling tower basin or Browns River. In addition, the water contents in the DWST can be gravity drained to the CST.

Screened Phase L.Criterion B - Intent Met.

tower Basin to Salem Seabrook is a single unit site. Seabrook is currently equipped with a four-train (two-SAMA #9 Service Water System as division) Ocean Service Water System. The alternate service water supply is provided by SAMA intent is met, therefore SAMA evaluation not sensitive to seismic Alternate Service Water the service water cooling tower, which consists of two pump divisions and a cooling tower risk, increase. No impact on SAMA evaluation.

Supply. water basin with a capacity of greater than 3M gallons. The cooling tower service water supply is independent of the ocean supply.

Screened Phase 1, Criterion B - Intent Met RCS cooldown and depressurization procedures are addressed in Seabrook SAMA #50.

Seabrook's emergency procedures include actions to cooldown and depressurize the RCS at Provide Procedural Guidance a rate of'30 to 50 Flhr while maintaining adequate subcooling margin and to establish SAMA#10 for Faster Cooldown on Loss conditions for operation of RHR shutdown cooling. These actions are currently modeled in SAMA intent is met, therefore SAMA evaluation not sensitive to seismic of RCP Seal Cooling. the PRA and any changes to further enhance the procedures are judged to have negligible risk increase. No impact on SAMA evaluation.

benefit on the accident sequences.

48 of 55

United States Nuclear Regulatory Commission SBK-L-I 1067 / Enclosure /Attachment A

ý,;I;!c.111 1 Ll § i II a i, b1iX1ý8 I- I- i;Sehbr&kStatioft, s1us.ing- eismi 111P 1:11:14 i:1111 W1'11ý1 iýý1l],

1'1(Qth6f-P ah 11, S D'Sebrookion( ;)s-l S ,.a..iEvaluation' .' .

Screened Phase 1. Criterion B- Intent Met Seabrook's charging system design includes two centrifugal charging pumps A and B and a Modify Plant Procedures to single positive displacement pump (PDP). The PDP is powered from a non-safety SAMA intent is met, therefore SAMA evaluation not sensitive to seismic SAMA #11 Make Use of Other Unit's electrical power source and requires component cooling from PCCW train B. The PDP is risk increase. No impact on SAMA evaluation.

PDP for RCP Seal Cooling, credited for seal injection in the loss of RCP seal injection initiating event in the PRA.

Replacement ofthis pump with a centrifugal pump was evaluated as Seabrook SAMA #

170.

Seabrook SAMA #192 (installation of flow limiting device in Control Improve Flood Barries This SAMA is applicable to Seabrook SAMA # 192, installation of flow limiting device in Building fire protection piping) has been evaluated for sensitivity to seismic SAMA12 Ouswieh of2 0 VControl Building fire protection piping. Refer to Seabrook response to RAI 1a. risk increase. This SAMA is potentially cost beneficial. Refer to Table X-2.

Screened Phase 2. Not Cost-Beneficial.

Expand AMSAC Function to Seabrook SAMA # 174 is j udged similar to this Salem Station SAMA for ATWS Seabrook SAMA #174 has been evaluated for sensitivity to seismic risk SAMA#14 Include Backup Breaker Trip mitigation. SAMA #174 evaluated the cost-benefit of providing an altemate scram button increase and has been shown not to be cost beneficial. Refer to Table X-2.

on RPS Failure. to remove power from the MG-sets to the control rod drives. This change was judged not cost-beneficial in the Seabrook Phase 2 assessment Enhance Procedures and Provide Additional Screened Phase 1. Criterion A - Not Applicable. SAMA not applicable, therefore SAMA evaluation not sensitive to seismic SAMA#17 Equipment to Respond to Seabrook Station does not have EDG control rooms or EDI control room ventilation risk increase. No impact on SAMA evaluation.

Loss of EDG Control Room systems.

Ventilation.

Screened Phase 1. Criterion B - Intent Met.

Provide Procedural Guidance Seabrook is a single unit site. Seabrook is currently equipped with a four-train (two-SAMA #24 to Cross-tie Salem I and 2 division) Ocean Service Water System. The alternate service water supply is provided by SAMA intent is met, therefore SAMA evaluation not sensitive to seismic Service Water Systems. the service water cooling tower, which consists of two pump divisions and a cooling tower risk increase. No impact on SAMA evaluation.

water basin with a capacity of greater than 3M gallons. The cooling tower service water supply is independent of the ocean supply.

Screened Phase 1, Criterion B - Intent Met In Addition to the Equipment This SAMA. involving seismic connections to alternate AFW water sources, is similar to Installed for SAMA 5, Install the current Seabrook capability. At Seabrook, the CST is seismically qualified and is Peraently Piped tecreteaoocaaiiyAtearoteCTisesialquifdanis SAMA intent is met, therefore SAMA evaluation not sensitive to seismic SAMA #27 Seismically Qualified protected from external events by a rugged, seismic structure. A permanent. seismically sk intent imct on SAMA evaluation.

Connections Qto temale qualified flanged connection exists to allow connection of an alternate water supply to the risk increase. No impact on SAMA evaluation.

AeW Water So n. EFW turbine driven pump suction and/or refill of the CST.

49 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A

..S.. ti. .on Silri.SW6ity;,-E.*adt.i.atioImo f ',Me-ýýk-&t:-; S- Riýk-W Itip'ller.of 1111, 11 iih' A !;I!;-

L; k)T:ý!, :ý11'HI i I I I alEv uaionIIII j'qp SkIIIII ;:,.I ýE:Ii onItoI Seiii I I .16&ei :ise M 1x1;:iiFi 1 iI.1:I iii~i Diablo Canydu Proposd SAMA Candidaites ____________________________

Improve Fire Barriers for Screened Phase 1. Criterion B - Intent Met.

ASW and CCW Equipment Additional barriers for fire areas were screened out based on the Seabrook Station plant SAMA intent is met, therefore SAMA evaluation not sensitive to seismic SAMA #12 in the Cable Spreading design with 3-hour rated fire barriers. Also, a review of the fire risk by location in the most risk increase. No impact on SAMA evaluation.

Room. recent update supports this screening that additional fire barriers would not significantly impact fire risk (refer to RAI 5.f)

Screened Phase 1, Criterion B - Intent Met The Cable Spreading Room (CSR) at Seabrook was screened from detailed evaluation Improve Cable Wrap for the based on the absence of ignition sources and the fact that only small amounts of transient SAMA intent is met, therefore SAMA evaluation not sensitive to seismic SAMA #13 PORVs in the Cable combustibles would likely be found in the area. Also, the area is equipped with fire risk increase. No impact on SAMA evaluation.

Spreading Room. detection and suppression. Cables for the two safety trains enter the room at different locations and are separated. Cables travel from the separate trays to the control room from through metal wire ways to the penetrations in the ceiling.

Screened Phase 2, Not Cost-Beneficial.

The context of this SAMA is that clearing of the water seals in the cold legs after core damage could result in a greater challenge to a SG thermally induced tube rupture (SGTI) due to the resulting unobstructed flow path of hot gas between the reactor vessel and SG(s).

Thus, a procedure change to ensure that the cold legs are not cleared would reduce the SGTI challenge and reduce the associated release. To assess this SAMA for Seabrook, Prevent Clearing of RCS PRA case XSGTIS was run, which eliminated 1001/6 of the potential for SGTI. The results SAMA evaluation not sensitive to seismic risk increase based on the low SAMA #24 Cold Leg Water Seals. of this case show that SGTI has minimal contribution to release. The reason SGTI does not benefit. No impact on SAMA evaluation.

contribute significantly to release is because successfully maintaining SG water inventory or depressurizing the RCS also effectively mitigate the SGTI tube rupture challenge. It is noted that the first two steps in Seabrook's Severe Accident Management Guideline (SAMG) diagnostic flow chart is to ensure SG water level greater than 10% narrow range and RCS pressure <285 psi. The associated nominal and upper bound cost-benefits of this SAMA are both less than $1K. This SAMA isjudged not cost-beneficial based on the estimated cost for a procedure modification, which is in the range of $15 to $201C Screened Phase 1, Criterion B - Intent Met.

The context of this SAMA is for plant procedures to ensure that there is sufficient water level in the Ss (preferably a faulted SG) so that fission product release through a Fill or Maintain Filled The postulated tube rupture will be reduced by scrubbing effects. At Seabrook, procedures SAMA #25 Steam Generators to Scrub specifically address SG water level and isolation of a faulted SG to minimize the possibility SAMA intent is met, therefore SAMA evaluation not sensitive to seismic Fission Products. of release. In addition,0 severe accident guidelines, which are entered before the onset of risk increase. No impact on SAMA evaluation.

core damage (at 1100 F), further address the importance to inject into the SGs and to maintain SO inventory for the purpose of: (1) protecting the SG tubes from creep rupture, (2) scrubbing fission products that could enter the SG from tube leakage, and (3) making the SGs available as a heat sink for the RCS.

50 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A

. . M. . .! i * . . . - .* .- H. . . V. *. ! , ;i F 1. ..-. i . , * . i : . . .. , . .

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.Voot~etatxouro1o idIA1%(!]ndidtes I.H. F- I F I, F Screened Phase 2, Not Cost-Beneficial.

Maintain full-time black start Seabrook Station is a single unit site with no other onsite power generation capability Seabrook SAMAs #13, #14 and # 156 have been evaluated for sensitivity to SAMA #2 capability of the Plant Wilson (except for onsite emergency and supplemental diesel generators). Installation of additional seismic risk increase and have been shown not to be cost beneficial. Refer combustion turbines. onsite power generation capability was evaluated in Seabrook SAMA #13 (buried offsite to Table X-2.

power source), SAMA #14 (gas turbine), and SAMA #156 (install alternate offiTe power source). These SAMA candidates were judged not cost-beneficial in Phase 2 Screened Phase 1. Criterion A- Not Applicable.

Prepare procedures and Seabrook Station is a single unit site with no other onsite power generation capability SAMA not applicable, therefore SAMA evaluation not sensitive to seismic SAMA #4 operator training for Cross- (except for onsite emergency and supplemental diesel generators). Phase I screening is risk increase. No impact on SAMA evaluation.

tying an opposite unit DG. consistent with Seabrook SAMA# 12, Create AC Cross-te Capability with Other Unit (multi-unit site).

Screened Phase 2, Not Cost-Beneficial.

The purposeof this Vogtle SAMA is to reduce the likelihood ofa Vogtde-specific SW failure mode that could lead to loss ofEDG cooling following a LOSP event. The proposed modification is to install redundant quick opening valves in parallel with existing cooling tower isolation valves, which are signaled to close and re-open during a LOSP event Failure to re-open would result in loss of cooling to the respective EDG. Thus, redundant SAMA evaluation not sensitive to seismic risk increase. No impact on Implementation of a bypass parallel valves would tend to increase the reliability of EDG cooling. The EDCs at SAMA evaluation. The proposed Vogtle SAMA is not applicable to SAMA #6 line for the cooling tower Seabrook are also cooled by Service Water (SW). SW to each EDG is normally isolated by Seabrook. The costs ofmodifying the SW system to accommodate parallel return isolation valves. a closed AOV designed to fail open on loss of power or instrument air. The AOVs open redundant valves would be similar to SAMA 161 with a cost estimate of automatically upon EDO demand and are not cycled closed and opened similar to the >$I M. A detailed less optimistic risk evaluation would further show this Vogtle design. The Seabrook AOVs have a history of reliable operation. As a result, option as being not cost-beneficial.

installation of redundant, parallel SW valves would not significantly improve EDG reliability and would not be cost-beneficial based on inspection of PRA Case NOSBO (which is very conservative) and cost of implementation judged to be on the order of

$500K. Detailed (less optimistic) evaluation would further show this option as being not cost-beneficial.

Screened Phase 2, Not Cost-Beneficial.

This Vogtle SAMA did not identify any specific procedural changes to improve the risk of ISLOCA events. Vogtle simply calculated a decrease in risk assuming elimination of all SAMA evaluation not sensitive to seismic risk increase. No impact on SAMA #16 Enhance procedures for ISLOCA risk. Seabrook PRA Case LOCA06 also quantified the risk benefit associated SAMA evaluation. ISLOCA procedures are sufficiently detailed and ISLOCA response. with elimination of ISLOCA risk. Based on this optimistic assessment, the UB benefit was evaluated in the PRA human reliability analysis. Any changes to procedures determined to be on the order of $53K. Based on a review of procedures, any changes to are judged not to have a significant beneficial impact on ISLOCA risk.

procedures are judged not to have a significant impact on ISLOCA risk. The cost of procedure changes and training are judged to be in the range of $30 to $40K. Detailed (less optimistic) evaluation would further show this option as being not cost-beneficial.

51 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A

'Tab~~~~~eX~~.~~AIuIW I Ietr.kSai~

,~sti't I~aiat~~~

1ýtiei usn Sesi RikI~ut 1 le ;2~~~

i yý y..*' 5k)I. aIf'if;$iI pi s ' i'e' t .1$I111 RI: . rok OrgI, Evaluation (!-5k) . . . . . . iisk Sesalcati-oe. ,i.

ii il I i:I! ~~ I 1i'H Ii hý1: -11 k I~.

I',

IndiadpointPropoedSAMACandidates II Not screened - Potentially Cost-Beneficial - however, similar to Seabrook SAMA #157 Portable Battery Charger- Seabrook SAMA # 157 (provide independent AC Installing portable diesel generator for charging batteries is similar to Seabrook SAMA power souce for battey chargers) has been evaluated for sensitivity to Provide a portable diesel- seismic risk increase. This SAMA is potentially cost beneficial. Refer to SAMA driven batty charger. # 157 (provide independent AC power source for battery chargers). This SAMA was shown to be potential cost beneficial to extend main station battery life during long term Table X-2.

SBO sequences.

Screened Phase I, Criterion B - Intent Met This SAMA is similar to Seabrook SAMA #66 and SAMA #75. Seabrook currently has Open city water supply valve the capability to connect several alternate water sources to supply the EFW suction header. SAMA intent is met, therefore SAMA evaluation not sensitive to seismic SAMA #52 for alternative AFW pump These include: the fire system using a diesel-driven fire pump, the portable diesel-driven risk increase. No impact on SAMA evaluation.

suction. pump with suction connected to the fire main, and the cooling tower portable makeup pump using either the cooling tower basin or Browns River. In addition, the water contents in the DWST can be gravity drained to the CST.

Screened Phase 1, Criterion B - Intent Met.

Provide hard-wired Seabrook currently has two, separate Remote Safe Shutdown (RSS) panels, one panel for connection to one SI or RHR each division. The panels are located in the respective divisional emergency switchgear SAMA intent is met, therefore SAMA evaluation not sensitive to seismic SAMA#55 pump from the Appendix R room. Each RSS division has the capability to use the associated EDG and emergency risk increase. No impact on SAMA evaluation.

bus (MCC 3I2A). buses to control/stabilize RCS inventory using boric acid transfer pump and/or high head charging pump: perform plant cooldown using ASDVs and EFW. and initiate shutdown cooling using an RHR pump.

Screened Phase I, Criterion B - Intent Met Upgrade the Alternate Safe Shutdown System (ASSS) to Seabrook's Remote Safe Shutdown (RSS) panels currently have the capability to provide SAMA intent is met, therefore SAMA evaluation not sensitive to seismic SAMA #61 allow timely restoration of both seal injection and cooling. Seal injection is provided using a high head charging risk increase. No impact on SAMA evaluation.

seal injection and cooling, pump. Seal cooling is provided using a thermal barrier cooling (TBC) pump with PCCW and SW pumps for heat sink SAMA #62 Install flood alarm in the This SAMA is applicable to Seabrook SAMA #192. installation of flow limiting device in Seabrook SAMA #192 (installation of flow limiting device in Control 480VAC switchgear room. Control Building fire protection piping. Refer to Seabrook response to RAI la. Building fire protection piping) has been evaluated for sensitivity to seismic risk increase. This SAMA is potentially cost beneficial. Refer to Table X-2.

52 of 55

United States Nuclear Regulatory Commission SBK-L- 11067 / Enclosure /Attachment A I 1 eabroktdo 1sn Senitiit ýSe9fism Risk MWi~

. ... .*:1 ... Ti ,

1 7.

I - I*I..

'1 '1 ' II 1 Wolf*C.ee*k Proposed SAM CaididAtes. .. .I : :

Screened Phase 1, Criterion B - Intent Met.

The context of this Wolf Creek SAMA is to reduce SBO RCP seal LOCA scenarios by installing an additional dedicated diesel generator power source for the normal charging Permanent- Dedicated pump (NCP). Seabrook currently has 2 EDGs that are dedicated to their respective Generator for the NCP with emergency bus. In addition, Seabrook has a third diesel generator unit - supplemental SAMA intent is met, therefore SAMA evaluation not sensitive to seismic SAMA #1 Local Operation of TD AFW emergency power supply (SEPS), which can be aligned from the control room to either risk increase. No impact on SAMA evaluation.

Afrer 125V Battery emergency power division. Once the breaker for SEPS is manually closed onto the aligned Depletion. bus, the load sequencer connects the required loads. Because SEPS can be quickly aligned from the control room to re-energize an emergency bus, restoration of the thermal barrier cooling and seal injection functions is accomplished in time to preserve RCP seal integrity and avoid seal failure.

Screened Phase 2, Not Cost-Beneficial.

Modify the Controls and Seabrook Station is a single unit site with no other onsite power generation capability Seabrook SAMAs #13, #14 and #156 have been evaluated for sensitivity to SAMA #2 Operating Procedures Sharpe Station to Allowforfor (exceptpower onsite for onsite emergency generation and supplemental capability was evaluateddiesel generators). Installation of additional in Seabrook SAMA # 13 (buried offsite seismic to Tablerisk X-2.

increase and have been shown not to be cost beneficial Refer Rapid Response. power source), SAMA #14 (gas turbine), and SAMA #156 (install alternate offsite power source). These SAMA candidates were judged not cost-beneficial in Phase 2.

Screened Phase 1,Criterion B - Intent Met.

The context of this Wolf Creek SAMA is to provide enhanced capability to cross-tie the SAMA #3 AC Cross-tie Capability. emergency 4kV buses. This SAMA is similar to Seabrook SAMA #11. Seabrook currently SAMA intent is met therefore SAMA evaluation not sensitive to seismic has 2 EDGs that are dedicated to their respective emergency bus. In addition, Seabrook has risk increase. No impact on SAMA evaluation.

a third diesel generator unit - supplemental emergency power supply (SEPS). which can be aligned to either emergency power division.

53 of 55

United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A iQ ! i 1 .111!!

1,1 lo"H A.1.1 iiblelX18ij iiýý'iýýS61115riii6kW iioni nsitivity, uAýon jo.! er, SAIIW IEOng: Seimmie Risk!Mulfipilei l6f I L l,; X;l 11:0F To, R'

(Oth YJ ItAIVLAslarelrorn z) roor:k iiýe i6 PA '60 .1,ýilý,ýý , d I'! , ýi 15 ' 111 1:!i 1111 I

]esii.'Evalualtioi.

i :! :; ; l ý i to eisiiic~Rs~nraeo2, .1li~_

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Screened Phase 2, Not Cost Beneficial.

The context of this Wolf Creek SAMA is to provide a procedural enhancement for operators to locally. manual close RHR valves to isolate an ISLOCA should the valves fail to close remotely. At Seabrook. ISLOCA events are postulated to occur in the RHR system due to: (1) multiple MOV failures in the RHR suction supply from the RCS hot legs, and (2) multiple check valve failures in the RHR injection lines to the RCS cold/hot legs.

Upgrade emergency Remote manual isolation of an ISLOCA event in RHR is detailed in plant EOPs. From a procedures to direct local PRA perspective, isolation ofa postulated ISLOCA originating from the RHR suction valve manual closure of the RHR failures is assumed not possible and thus is not credited in the PRA, Isolation of a SAMA evaluation not sensitive to seismic risk increase based on the low SAMA 4 EJHV8809A and postulated ISLOCA originating from RHR injection valve failures is possible via manual benefit There is no change to the SAMA conclusion based on the original EJHV8809B valves ifthey closure of valve RH-MOV-14 or RH-MOV-26. However, only limited isolation credit is Seabrook evaluation.

fail to close remotely, given in the PRA for events when RHR relief valves are successful and RHR piping and heat exchanger pressure boundaries remain intact. Thus, ISLOCA leakage is a result of relief valve opening and RHR pump seal degradation. Failure of the operator action to isolate RHR. valve 14 (26) has an RRW of only 1.0001. Given this extremely low risk reduction, the actual cost-benefit of making improvements to associated procedures or valve hardware will be well below the range of $28K to $53K, which assumed elimination of all ISLOCA risk in PRA Case LOCA06. Therefore, this SAMA is judged not cost-beneficial.

Screened Phase I, Criterion B - Intent Met.

The context of this Wolf Creek SAMA is to provide for alternate EDG room cooling during favorable outdoor ambient temperature conditions by opening room doors. At Seabrook, the diesel air handling (DAH) systems consists of a supply and exhaust fan and associated Enhance procedures to direct dampers for ventilating/cooling the respective diesel room. The DAH is included in the operators to open EDG PRA model due to the relatively short heatup times. Note, however, that during a SAMA intent is met therefore SAMA evaluation not sensitive to seismic SAMA o5 Room oren ae substantial time of the year. the outside temperature is low enough that ventilation may not risk increase. No impact on SAMA evaluation.

doorsforaltemate be required. DAH compensatory ventilation actions exist for maintaining acceptable DG room temperatures depending on outdoor ambient temperatures when DAH components are unavailable. In addition, DG room high temperature alarm response procedures recommend several actions including monitoring of DG temperatures and providing portable fans to cool the affected room.

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United States Nuclear Regulatory Commission SBK-L-1 1067 / Enclosure /Attachment A I I ' "I ." I, I.I : .- i, ..'I., : 11 . i !.::l .: .i, i ' '1.i :i . - I : .. S -n , I .s:., -".,.tIi i" . I , I. I Screened Phase 1,Cniterion B- Intent Met..

Scabrook currently has 2 ED~s that are dedcaled to their respective emergency bus. The capability to cross-tie the divisional EDG fuel oil tanks exists. Fuel oil ma~keup to t.he respective EDO day tank is accomplishedl via the dlivisional fuel oil transfer pump. Gravity drain from the fuel oil storage tanks to the associated day tank is not practical. However, Altemnative Fuel Oil Tank the discharge from each fuel oiltransfer pump can be aligned to supply the opposite SAMA intent is met, therefore SAMA evaluation not sensitive to seismic SAMA #13 with Gravity Feed Capability, division EDO day tank. This provides flexibility to maintain day tank inventory should a risk increase. No impacton SAMA evaluation.

problem develop with one transfer pump. Inaddition, as noted above. Scabrook has a third diesel generator unit - supplemental emergency power supply (SEPS), which can be aligned to either emergency power division. The SEPS has a dedicated fuel oil, independent of the EOfuel oil.

Screened Phase I, Criterion B - Intent Met The context of this Wolf Creek SAMA issimilar to Wolk Creek SAMA #1 but with increased diesel generator capacity to also operate a meotor-driven AW pump. As noted above, Seabrook has already installed a third diesel generator unit - supplemental Permanent, Dedidated emergency power supply (SEPS), which can be aligned from the control room to either SAMA #14 Generator for the NCP one eergency power division. Once the breaker for SEPS eis anually losed Onto the aligned SAMA intent is met, therefore SAMA evaluation not sensitive to seismic Motor Driven AFW Pump, bus, the load sequencer connects the required loads. Because SEPS can be quiekly aligned risk increase. No impact on SAMA evaluation.

and a Battery Charger. from the control room to re-energize an emergency bus, restoration of the thienal barrier cooling and seal injection functions is accomplished in time to preserve RCP seal integrity and avoid seal f1ilure. The SEPS diesel generator load is maintained at or below 5280kW.

This is sufficient capacity to operate may important systems including motor-driven EFW and_ aBatteryCharger. pump or the startup feedwater pump, SW pump, PCCW pump. batteiy charger. ete.

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v t e Letter Sequence Response to RAI
TAC:ME3959, (Approved, Closed)
Initiation Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request Acceptance, Acceptance Supplement Administration Meeting, Meeting, Meeting Questions 31 July 2012 29 October 2010 21 December 2010 16 November 2010 3 January 2011 28 February 2011 4 March 2011 7 April 2011 20 March 2012 16 July 2012 1 November 2012 Answers 23 November 2010 23 November 2010 23 November 2010 23 November 2010 23 November 2010 23 November 2010 23 November 2010 23 November 2010 23 November 2010 23 November 2010 23 November 2010 22 January 2014 22 January 2014 22 January 2014 23 November 2010 23 November 2010 13 January 2011 16 March 2011 18 April 2011 10 June 2011 13 September 2012 22 January 2014 6 September 2016 Results Approval, Approval, Approval, Approval, Approval, Approval, Approval Other: ML103070056, ML103360209, ML103360212, ML11126A365, ML11343A025, ML12352A141, ML13352A511, ML13353A536, ML18127A116
MONTHYEAR2010-08-10 [Table View]

SBK-L-11067, Response to Request for Additional Information, NextEra Energy Seabrook License Renewal Application

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SBK-L-11067, Response to Request for Additional Information, NextEra Energy Seabrook License Renewal Application

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