ML11285A481

2011/09/19 Watts Bar 2 OL - TVA Letter to NRC_09-16-11_Revided Samda Response

ML11285A481
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Site:	Watts Bar
Issue date:	09/19/2011
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To:	Division of Operating Reactor Licensing
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Download: ML11285A481 (142)

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WBN2Public Resource From: Boyd, Desiree L [dlboyd@tva.gov]

Sent: Monday, September 19, 2011 8:27 AM To: Epperson, Dan; Poole, Justin; Raghavan, Rags; Milano, Patrick; Campbell, Stephen Cc: Arent, Gordon; Hamill, Carol L; Boyd, Desiree L; Crouch, William D

Subject:

TVA letter to NRC_09-16-11_Revided SAMDA Response Attachments: 09-16-11_Revided SAMDA Response_Final.pdf Please see attached TVA letter that was sent to the NRC.

Thank You,

~*~*~*~*~*~*~*~*~*~*~*~

Désireé L. Boyd WBN 2 Licensing Support Sun Technical Services dlboyd@tva.gov 423-365-8764 1

Hearing Identifier: Watts_Bar_2_Operating_LA_Public Email Number: 526 Mail Envelope Properties (7AB41F650F76BD44B5BCAB7C0CCABFAF232E99A4)

Subject:

TVA letter to NRC_09-16-11_Revided SAMDA Response Sent Date: 9/19/2011 8:27:27 AM Received Date: 9/19/2011 8:27:38 AM From: Boyd, Desiree L Created By: dlboyd@tva.gov Recipients:

"Arent, Gordon" <garent@tva.gov>

Tracking Status: None "Hamill, Carol L" <clhamill@tva.gov>

Tracking Status: None "Boyd, Desiree L" <dlboyd@tva.gov>

Tracking Status: None "Crouch, William D" <wdcrouch@tva.gov>

Tracking Status: None "Epperson, Dan" <Dan.Epperson@nrc.gov>

Tracking Status: None "Poole, Justin" <Justin.Poole@nrc.gov>

Tracking Status: None "Raghavan, Rags" <Rags.Raghavan@nrc.gov>

Tracking Status: None "Milano, Patrick" <Patrick.Milano@nrc.gov>

Tracking Status: None "Campbell, Stephen" <Stephen.Campbell@nrc.gov>

Tracking Status: None Post Office: TVANUCXVS2.main.tva.gov Files Size Date & Time MESSAGE 285 9/19/2011 8:27:38 AM 09-16-11_Revided SAMDA Response_Final.pdf 729539 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 September 16, 2011 10 CFR 50.4 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 Docket No. 50-391

Subject:

WATTS BAR NUCLEAR PLANT (WBN) - UNIT 2 - REVISED SEVERE ACCIDENT MANAGEMENT DESIGN ALTERNATIVE REVIEW (SAMDA) RESPONSE (TAC NO. MD8203)

References:

1. TVA to NRC letter dated June 17, 2011, Watts Bar Nuclear Plant, Unit 2 - Response To Request For Additional Information Regarding Severe Accident Management Design Alternative Review (SAMDA) (TAC NO. MD8203)

2. TVA to NRC letter dated May 25, 2011, Watts Bar Nuclear Plant (WBN) - Unit 2 - Response to Request for Additional Information Regarding Severe Accident Management Design Alternative Review (TAC No. MD8203)

3. TVA to NRC letter dated January 31, 2011, Watts Bar Nuclear Plant (WBN) - Unit 2 - Response to Request for Additional Information Regarding Severe Accident Management Alternative Review (TAC NO. MD8203)

4. TVA to NRC letter dated November 1, 2010, Watts Bar Nuclear Plant (WBN) Unit 2 - Severe Accident Management Alternatives Using Latest Computer Aided Fault Tree Analysis Model -

Additional Information (TAC MD8203)

The purpose of this letter is to provide revisions to data results and conclusions contained within References 1, 2, 3, and 4 regarding the Severe Accident Management Design Alternatives (SAMDA) analysis. These revisions stem from a misinterpretation of the consequence model output for total person-rem for each of several assessed release categories and from two less significant source term errors.

The Enclosure summarizes the changes, the impacts on SAMA evaluations, and the responses to RAIs. Specifically, the following tables are revised:

U.S. Nuclear Regulatory Commission Page 3 September 16, 2011 bcc (Enclosure):

Stephen Campbell U.S. Nuclear Regulatory Commission MS 08H4A One White Flint North 11555 Rockville Pike Rockville, MA 20852-2738 Charles Casto, Deputy Regional Administrator for Construction U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., N.E., Suite 1200 Atlanta, GA 30303-1257

Enclosure 1 Revised Results/Conclusion to Previous Watts Bar Unit 2 SAMDA Responses

ENCLOSURE 1 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION Following the response to RAIs up to and including the TVA submittal of June 27, 2011, an error was discovered by NRC and confirmed by ABS in the interpretation of the MACCs output for total person-rem for each of the assessed release categories. This error underestimated the total person-rem computed, thereby requiring a reanalysis of the identified SAMAs with the corrected person-rem values. The total person-rem exposures are one type of input to the total consequences evaluated in units of dollars for each release category. Direct economic costs are another type of input and this other type constitutes the greatest contribution to total consequence costs. Further independent checking resulted in a change to the computed source terms for release category case, Early 1B and an insignificant reduction in the source terms for release category case, Early 2A. All of these changes have been corrected and the resulting SAMA cost-benefit analysis reevaluated. The changes in results are documented in the form of a succinct statement of changes to the SAMA analysis submittals; i.e. the original SAMA report submitted in October, 2011 and all subsequent responses to RAIs.

The following summarizes the changes, the impacts on SAMA evaluations, and the responses to RAIs. In some cases, tables presented in one submittal were reviewed in later responses to RAIs.

In the summary below, only changes to the last submitted table are provided. When these revised tables were presented in earlier submittals, a cross-reference is provided to the final tables documented herein. The changes are presented in chronological order by submittal date of the past SAMAs reports, beginning with the submittal of October 2010.

Submittal of October 4, 2010 The findings of a review of the October 4, 2010 submittal of the Watts Bar Unit 2 Severe Accident Mitigation Alternatives report to account for correcting the total person-rem computed for each release category are provided below. A number of tables which initially appeared in the October 4, 2010 submittal must be updated to reflect these changes. Some of these tables have already been updated previously in response to subsequent RAIs on the October 4, 2010 submittal. The following cross-reference table directs the reader to the updated table numbers and the associated submittal date under which heading below, the final, updated table may be found.

October 4, 2010 Revised Table Date of Submittal Table Number Number in RAI when Table last Responses changed 8 2.a.iv-4a June 17, 2011 10a 2.a.iv-6 June 17, 2011 16 15-1 May 25, 2011 17 2.a.iv-8 January 31, 2011 18 2.a.iv-9 January 31, 2011 19 2.a.iv-10 January 31, 2011 20 2.a.iv-11 January 31, 2011 1

Two additional tables appearing in the October 4, 2010 are also changed to correct the total person-rem computed for each release category. These are Tables 10b and 21 below.

Table10b.Annual80Kilometer(50mile)PopulationDoseandEconomicCostRisk

Population Dose Risk Economic Cost Risk Release Category (person-rem/year) (dollars/year)

I - LERF 3.73 7.99 x 103 II - BYPASS 0.84 1.86 x 103 III - LATE 14.14 4.14 x 104 IV- ISERF 1.24 2.25 x 103 2

Table21.EvacuationSpeedSensitivitySAMACaseResults

Benefit/ Benefit/ Benefit/

SAMA Cost Cost Cost Change in SAMA Title No. Ratio Ratio Ratio Conclusion 2.2 mph 3.4 mph 1.6 mph 4 Improve DC bus load shedding. 1.26 1.26 1.27 NO Increase training on response to loss of two 8 120V AC buses which causes inadvertent 0.47 0.47 0.47 NO actuation signals.

Provide an additional high pressure injection 26 0.02 0.02 0.02 NO pump with independent diesel.

Add the ability to automatically align emergency core cooling system to 32 0.19 0.19 0.20 NO recirculation mode upon refueling water storage tank depletion.

Enhance procedural guidance for use of cross-45 tied component cooling or service water 0.16 0.16 0.16 NO pumps.

46 Add a service water pump. 0.14 0.14 0.14 NO Install an independent reactor coolant pump 56 seal injection system, without dedicated 0.15 0.15 0.15 NO diesel.

Install accumulators for turbine-driven 70 0.39 0.39 0.40 NO auxiliary feedwater pump flow control valves.

Install a new condensate storage tank 71 0.00 0.00 0.00 NO (auxiliary feedwater storage tank).

Replace service and instrument air compressors with more reliable compressors 87 0.00 0.00 0.00 NO which have self-contained air cooling by shaft driven fans.

Install an unfiltered, hardened containment 93 0.40 0.40 0.40 NO vent.

Provide a reactor vessel exterior cooling 101 0.08 0.08 0.09 NO system.

Institute simulator training for severe accident 103 0.18 0.17 0.18 NO scenarios.

109 Install a passive hydrogen control system. 0.08 0.08 0.08 NO Erect a barrier that would provide enhanced protection of the containment walls (shell) 110 0.09 0.09 0.09 NO from ejected core debris following a core melt scenario at high pressure.

Add redundant and diverse limit switches to 112 0.00 0.00 0.00 NO each containment isolation valve.

Install motor generator set trip breakers in 136 0.06 0.05 0.06 NO control room.

NO. Proposed Eliminate RCP thermal barrier dependence on procedure 156 CCW, such that loss of CCW does not result 24.70 24.67 24.77 change directly in core damage. ineffective.

See Sec. 10 Provide a connection to alternate offsite power 176 0.09 0.09 0.09 NO source.

191 Provide self-cooled ECCS seals. 0.00 0.00 0.00 NO Provide a means to ensure RCP seal cooling 215 so that RCP seal LOCAs are precluded for 0.88 0.88 0.88 NO SBO events.

3

Table 21. Evacuation Speed Sensitivity SAMA Case Results (Continued)

Benefit/ Benefit/ Benefit/

SAMA Cost Cost Cost Change in SAMA Title No. Ratio Ratio Ratio Conclusion 2.2 mph 3.4 mph 1.6 mph Permanent, self- powered pump to backup 226 0.49 0.49 0.49 NO normal charging pump.

Permanent, Dedicated Generator for the NCP, 255 one Motor Driven AFW Pump, and a Battery 0.26 0.26 0.26 NO Charger.

Install Fire Barriers Around Cables or Reroute 256 56.11 55.95 56.45 NO the Cables Away from Fire Sources.

Provide an auto start signal for AFW on loss 276 0.04 0.04 0.04 NO of Standby Feedwater pump.

Provide a permanent tie-in to the construction 279 0.08 0.08 0.08 NO air compressor.

Add new Unit 2 air compressor similar to the 280 0.09 0.09 0.09 NO Unit 1 D compressor.

282 Provide cross-tie to Unit 1 RWST. 0.00 0.00 0.00 NO Improve training to establish feed and bleed 285 cooling given no CCPs are running or a vital 3.85 3.85 3.86 NO instrument board fails Improve training to reduce failure probability 292 to terminate inadvertent safety injections prior 14.78 14.55 15.18 NO to water challenge to PORVs Increase frequency of containment leak rate 295 0.06 0.06 0.06 NO testing Initiate frequent awareness training for plant 299 operators/ maintenance/ testing staff on key 10.66 10.65 10.69 NO human actions for plant risk Revise procedure FR-H.1 to eliminate or simplify complex (and/or) decision logic for 300 establishing feed and bleed cooling and to 0.57 0.57 0.57 NO improve operator recovery from initial mistakes Move indication/ operator interface for 303 0.03 0.03 0.03 NO starting hydrogen igniters to front MCR panel Add annunciator or alarm signaling 304 parameters to initiate hydrogen igniters to 0.03 0.03 0.03 NO front panel on MCR Revise procedure E-1 to include recovery Not Not Not 305 Estimated Estimated Estimated NO steps for failure to initiate hydrogen igniters Improve operator performance by enhancing Not Not Not 306 Estimated Estimated Estimated NO likelihood of recovery from execution errors Make provisions for connecting ERCW to 307 0.00 0.00 0.00 NO CCP 2B-B The list of conclusions in Section 10 of the October 4, 2010 submittal is unchanged, with one exception. SAMA 215 is now only to be considered if SAMA 58, which addresses the same RCP seal LOCA sequences, is not implemented. See the updated commitment in enclosure 2 of the submittal of May 25, 2011.

RAI Response Submittal of January 31, 2011 4

The findings of a review of the January 31, 2011 submittal in response to RAIs to account for correcting the total person-rem computed for each release category are provided below.

TVAs responses to items 1 through 2 of this submittal have been reviewed and concluded to be unchanged by correcting the total person-rem computed for each release category.

For item 3, a number of Tables which initially appeared in the January 31, 2011 submittal must be updated to reflect these changes. Some of these tables have subsequently been updated in response to later RAIs. These include Tables 2.a.iv-4 and 2.a.iv-6, which were last updated in the RAI response submittal of June 17, 2011; i.e. see the updated tables under that heading below.

Additionally, Tables 2.a.iv-7 through 2.a.iv-11, Table 4.d-2 and 5.c-1 are changed as a result of correcting the total person-rem computed for each release category. These updated tables are presented below.

Item 4a of this submittal concerns the identification and screening of candidate SAMAs. TVA used the basic event RRW values to CDF and to LERF to identify the key basic events for purposes of identification of candidate SAMAs. RRW cutoffs for identification were justified on the basis of the maximum averted cost risk (MACR) at that time and minimum costs applicable for training ($26,773) and for hardware fixes ($100,000). The cutoffs selected previously are modified here to reflect the changed MACR values after correcting the total person-rem computed for each release category.

Submittal date CDF LERF Training/ HRA Hardware Training/ HRA Hardware

$26,773 $100,000 $26,773 $100,000 1/31/2011 1.007 1.026 1.0293 1.117 September 2011 1.006 1.0227 1.0437 1.1817 A revision to Table 4.a.i-1, presenting the basic events with RRW greater than 1.006 is provided below. For CDF, four additional basic events are identified as having RRWs between 1.026 and 1.022; i.e. DGGFD2GEN_0822B-B, MTM_2GEN_0822B-B, U0_ERCW_PMP_FR_CCF_IE_ALL, and HAERCW3. All of these events were already evaluated for potential SAMAs in Table 4ai-1 of the January 31, 2011 submittal. No additional SAMAs are therefore identified for hardware fixes contributing to CDF at the revised RRW screening value.

For operator training and HRA related basic events contributing to CDF, two new HRA related basic events of lower importance now just exceed the lower RRW threshold of 1.006. These events are dependent HRA combinations named HRADEP-POST-293 and HRADEP-POST-193.

Three of the human actions which are included in these two dependent action groups have already been evaluated for potential improvements; i.e. for actions HARR1, HAFR1 and AFWOP3. The remaining human action event, used in both of these two dependent action combinations was not previously evaluated for potential SAMAs; i.e. HAMU2B - Makeup to 5

RWST using containment spray test recirculation from the containment sump during a small LOCA. This action outside the control room has an HEP value of 5E-3. The contributors to this human error probability are both from cognitive errors (3.1E-03) and from execution errors (1.9E-03). The cues and indications for this action are good and procedure ECA-1.1, Appendix C is clear in its direction of the action. A new SAMA, number 340, is defined here to improve the error rate for action HAMU2B by additional training.

As a Phase 1 screening analysis, we note that this new SAMA is at best marginal because even if the entire benefits of eliminating this error rate were obtained, the cost-benefit would be just

$26,773 considering the 2.28 multiplier and the 2.7 uncertainty on the CDF frequency. More likely the training should address both operations staff (to reduce the cognitive error rate) and those performing the action locally (execution errors). Further, the same procedure (ECA-1.1, step 10b) directs the operators to notify the TSC to evaluate transferring water to the RWST from other sources. These backup actions are not yet credited in the PRA model. Therefore, accounting for these other water sources as a means to lowering the 5E-3 error rate would further reduce the perceived benefit. New SAMA 340 is therefore considered screened on very low benefit.

For the LERF metric, the above RRW cutoff comparison table shows that the minimum RRW factors have increased from the previous evaluation. This is because the offsite exposure and offsite economic data from the October 4, 2011 used in the previous evaluation of these factors has changed. While the offsite economic costs for the early release category have gone up since the October 4, 2011 submittal, the offsite economic costs for the bypass release category have gone down by a greater amount. The latest consequence values for release categories were used in computing the revised RRW cutoffs. As a result, it now takes a greater change in LERF frequency to obtain the same benefit. Since the basic events with the lower LERF RRWs were evaluated for potential SAMAs in the January 31, 2011 submittal, no further potential SAMAs to reduce LERF need be postulated here. Table 4.a.ii-1 is unchanged and, therefore, not repeated here.

The RAI responses to item 4b (WBN1 IPE insights), item 4c (IPEEE seismic review screening),

item 4d (FIVE related SAMAs) , item 4e (Phase I screening justifications), item 4f (internal flood prevention), item 4g (SAMA 242 screening), and item 4h (SAMA 296 screening) are all confirmed after correcting the total person-rem computed for each release category. The Phase I screening documented in Table 16 of the October 4, 2010 submittal is accurate as is and need not be updated.

For item 5, the conclusions of the Phase II cost-benefit calculations are unchanged. Tables summarizing the numerical changes caused by correcting the total person-rem computed for each release category are provided below. Table 2.a.iv-10 shows that the cost-benefit ratio for SAMA 93 went up from 0.95 to 1.08 and for SAMA 70 from 0.93 to 1.06. for the 95% CDF sensitivity case. However, these two SAMAs are already being addressed. The benefits of SAMA 70 will be reduced by TVAs commitment to implement SAMA 339. SAMA 93 will be evaluated further should SAMA 58 not prove reliable.

For item 6, the conclusions regarding the Phase I screening when considering the 95% results for 6

both CDF and LERF are unchanged after correcting for the total person-rem computed for each release category.

For item 7, the response is affirmed.

The list of 10 commitments in Enclosure 2 to this submittal is again affirmed. One exception is that for item 1, addressing SAMA 58. This commitment is restated as a revised commitment in enclosure 2 to the RAI response submittal of May 25, 2011. This restatement of the commitment is unrelated to correcting the total person-rem computed for each release category.

7

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs Red SAMA Event Name Probability W SAMA Title Discussion SAMA # Description Reduce 50, 58, probability of 61, 155, large seal Upgrade seals or 242, 260 leak given enhance loss of all procedures to RCP seal cooldown RCS RCPSEAL182 2.07E-01 1.337 cooling before leakage RCP SEAL 182 GPM Loss of Offsite Power

%0LOSP-GR 1.01E-02 1.227 (Grid Related)

In training, Reduced human 22 emphasize error probability steps in during off-site recovery of power recovery.

off-site power after an SBO.

Bury off-site Improved off-site 24 power lines. power reliability during severe weather.

Provide a Increases offsite 176 connection power to alternate redundancy.

offsite power source.

8

Table 4ai Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red SAMA Event Name Probability W SAMA Title Discussion SAMA # Description Provide an Increased 9 additional availability of on-Onsite AC power additionally diesel site emergency AC fails generator. power.

Revise Extended diesel 10 procedure to generator allow operation.

bypass of diesel generator trips.

Improve Increased 11 4.16-kV bus availability of on-cross-tie site AC power.

capability.

9

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Cross-tie Increased 12, 229, 244 diesel availability of on-site generators AC power.

Onsite AC power within or to additionally fails the other (Continued) unit's Provide for open doors or use 160, 246 improved adjacent room's credit to be exhaust fans taken for loss of HVAC sequences, especially for the DG electric board rooms 10

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description 182 gpm RCP seal LOCA Implement Unit 2 has the 58, 232 results from SBO enhanced upgraded high RCP seal temperature o-rings design. in the Reactor Coolant Pumps. A new seal insert design has been proposed by Westinghouse which could eliminate seal LOCA sequences.

Pending topical report approval, this alternate seal design may prove cost effective, however costs are unknown at this time.

Long term AFW fails during Create ability Increased 66, 67, 75 Station Blackout for availability of emergency feedwater.

connection of existing or new water sources to feedwater and condensate systems.

Plant availability PLANT AVAILABILITY PAF 9.03E-01 1.226 N/A factor - FACTOR 11

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Loss of Offsite Power

%0LOSP-PC 8.12E-03 1.19 - see %0LOSP-GR - (Plant Centered)

Improve Upgrade unit 2 TD-reliability of AFW pump PUMP FAILS TO TD AFW START AND RUN FOR PTSF12PMP_003001AS 2.43E-02 1.136 pump 223 1 HOUR WBN-1-3-1AS Total Loss of Component Cooling

%2CCS 1.00E+00 1.105 System Unit 2 Common cause failure of Incorporate Improves reliability 274 all CCS pumps diverse of CCS system.

positive displacement pump for CCS Operators fail (HCCSR4) to Improve Procedure (AOI-15) 51260, 299 align ERCW to train A training to already provided for charging pump align and loss of CCS.

initiate Enhance training to alternate improve chances of cooling to 2A- success.

A or 2B-B CCPs when failed 12

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description 182 gpm seal LOCA Implement Unit 2 has the 58, 232 develops enhanced upgraded high RCP seal temperature o-rings design. in the Reactor Coolant Pumps. A new seal insert design has been proposed by Westinghouse which could eliminate seal LOCA sequences.

Pending topical report approval, this alternate seal design may prove cost effective, however costs are unknown at this time.

Reduce probability of can improve core damage procedures to cope from seal with loss of CCS CCF of CCS PUMPS LOCAs (cool-down RCS or 45, 49, 50, FAIL TO RUN, CCS HX resulting from cross-tie to ERCW), 53, 56, 59, PLUGGS, & CCS HX U0-CCS-PCO-FR-CCF-IE- a loss of CCS add a diverse CCS 61, 64, 156, EXCESSIVE ALL 2.75E-04 1.105 system pump 157, 158 LEAKAGE/RUPTURE 13

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve Providing nitrogen 70, 73,299 training for bottles as loss of air accumulators for after plant trip selected valves Restore AFW control would reduce action following initiator and HAFR1 3.70E-03 1.088 difficulty loss of air SUMMER 2.00E-01 1.082 N/A Fraction of year - SUMMER SEASON Loss of Offsite Power

%0LOSP-WI 2.03E-03 1.067 - see %0LOSP-GR - (Weather Induced)

Raw water Eliminate flood 293 pipe break in propagation path 5th vital from battery room to battery room 480v shutdown propagates to board rooms 480v shutdown boards causing Flood event induced by station rupture of RCW line in

%0FLRCW772A8 1.06E-06 1.066 blackout room 772.0-A8 Raw water Eliminate flood 294 pipe break in propagation path HEPA filter from HEPA filter room room to 480v propagates to shutdown board 480v rooms shutdown boards causing Flood event induced by station rupture of RCW line in

%0FLRCW772A9 1.06E-06 1.066 blackout room 772.0-A9 14

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description FL-BATDEP 1.00E+00 1.065 N/A Flag event - Battery Depleted FLAG Improve Procedure (AOI-15) 51,260 training to already provided for align and loss of CCS.

initiate Enhance training to alternate improve chances of cooling from success.

ERCW to 2A-A or 2B-B ALIGN AND INITIATE CCPs when ALTERNATE COOLING HCCSR2 1.60E-02 1.06 CCS failed TO CCP 2A-A

%0TLERCW 1.00E+00 1.059 299,307 Total Loss of ERCW Common cause failure of Refurbish the Improves the 271 all ERCW pumps or ERCW pumps reliability of the strainers & upgrade the ERCW pumps.

capacity of the current pumps.

15

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Dependence of CVCS and Implement The initiation of 154, 215 SI Injection on ERCW procedure to charging flow from open the the opposite unit CVCS cross- should provide tie valve to sufficient RCP seal the opposite cooling to prevent unit early in RCP seal damage.

the accident Another option is the response, or installation of a new, installation of independently a new, powered pump, independently powered pump Create a Allows low pressure 41 reactor emergency core coolant cooling system depressurizati injection in the event on system. of small LOCA and high-pressure safety injection failure.

16

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description 182 gpm pump seal LOCA Implement Unit 2 has the 58, 232 enhanced upgraded high RCP seal temperature o-rings design. in the Reactor Coolant Pumps. A new seal insert design has been proposed by Westinghouse which could eliminate seal LOCA sequences.

Pending topical report approval, this alternate seal design may prove cost effective, however costs are unknown at this time.

17

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Dependence of AFW LCVs Provide a Improve availability 279, 280, on compressed air permanent of air system. 281 tie-in to the construction air compressor, or add new Unit 2 air compressor similar to the Unit 1 D compressor, or replace the ACAS compressors and dryers.

Short term AFW fails (e.g. Improve Providing nitrogen 70, 73 operators fail to locally training for bottles as control LCVs for TD AFWP loss of air accumulators for (compressed air is lost), after plant trip selected valves HAFR1 would reduce action difficulty 18

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Create ability Increased 66, 67, 75 for availability of emergency feedwater.

connection of existing or new water sources to Long-term AFW fails due to feedwater and partial dependence on condensate ERCW systems.

DIESEL GENERATOR FAILS TO RUN AFTER DGGFR2GEN_0822A-A 1.46E-02 1.048 FIRST HOUR Provide a 2 Improves availability 9 MW blackout of AC power during diesel SBO.

generator to power Charging Pumps, Igniters, Inverters, etc Revise extend diesel 10 procedure to generator operation allow bypass of diesel generator trips 19

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve 4.16- Increased 11 kv bus availability of on-site crosstie AC power.

capability Cross-tie Increased 12, 229, 244 diesel availability of on-site generators AC power.

within or to the other unit's Recovery Sequence 7 (Common Cause of DG XSBO14 4.59E-02 1.042 - See %0LOSP-GR - to Start) GR

- See -

DGGFR2GEN_0822 DIESEL 2A-A MTM_2GEN_0822A-A 1.51E-02 1.042 A-A MAINTENANCE

- See - DG 2B-B FAILS FAILS DGGFR2GEN_0822 TO RUN (WBN-2-GEN -

DGGFR2GEN_0822B-B 1.46E-02 1.042 A-A 082-0002B -B)

Recovery Sequence 7 (Common Cause of DG XSBO13 5.60E-02 1.042 - See %0LOSP-GR - to Start) PC Small LOCA Stuck Open Safety Relief

%2SLOCAL 2.88E-03 1.039 Valve 20

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Failure of high pressure Improve Existing EOPs 31,32, 34,36, recirculation from the operator provide directions 187,238, sump, HARR1 performance for monitoring and 247,299 and minimize conserving water in need for the containment manual action recirculation sump.

to complete These procedures high pressure are already used recirculation extensively in alignment license operator initial training and license operator continuing training programs, and are Align high pressure practiced in the plant recirculation, given auto simulator. swap over works Failure to cooldown and Failure to Improve operator Procedure 307 depressurize, AFWOP3 cooldown and performance by ECA-1.1, depressurize, enhancing likelihood loss of RHR AFWOP3 of recovery from sump execution errors recirculation, governs this action Failure to refill the RWST Failure to refill Improve operator Procedure 33, 249,282, 306 using containment spray the RWST performance by ES-1.3 pumps, HACH1 using enhancing likelihood transfer to containment of recovery from containment spray pumps, execution errors sump HACH1 governs this action 21

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Recovery Sequence 4 (DG A And B Fail to Start And TDAFW Fails XSBO11 6.62E-01 1.039 - See %0LOSP-GR - to Start) GR Restore AFW control following HELB scenario induced by MSS supply to AFW line break. Unit HAFR1_FL 1.00E+00 1.038 N/A Flag event - 2, 1.0 FL-ATWS 1.00E+00 1.038 N/A Flag event - ATWS Provide for open doors or use 160, 246 improved adjacent room's credit to be exhaust fans taken for loss of HVAC sequences, especially for BOARD ROOM the DG EXHAUST FAN FAILS electric board TO START OR RUN FNSFD2FAN_030460 9.13E-03 1.035 rooms FIRST HOUR Recovery Sequence 8 (Common Cause of DG to Start AND TDAWF XSBO17 6.62E-01 1.035 - See %0LOSP-GR - Fails to Start) GR Recovery Sequence 4 (DG A And B Fail to Start And TDAFW Fails XSBO10 7.06E-01 1.033 - See %0LOSP-GR - to Start) PC 22

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Provide for open doors or use 160, 246 improved adjacent room's credit to be exhaust fans taken for loss of HVAC sequences, especially for BOARD ROOM the DG EXHAUST FAN FAILS electric board TO START OR RUN FNSFD2FAN_030462 9.13E-03 1.032 rooms FIRST HOUR Improve Upgrade unit 2 TD- 223 reliability of AFW pump TD AFW PUMP WBN-2-3-1AS IN MTM_2PMP003001AS 8.52E-03 1.031 pump MAINTENANCE Recovery Sequence 8 (Common Cause of DG to Start AND TDAWF XSBO16 7.06E-01 1.03 - See %0LOSP-GR - Fails to Start) PC HRADEP-POST-221 8.60E-04 1.028 HAOB2 Goal is to Enhanced 79, 283,285, reduce error procedures already 300 rate for implemented, operator additional training action to could reduce error initiate feed rate Establish RCS Bleed and bleed and Feed cooling given 1.60E-02 cooling no CCPS running 23

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description HAFR1 Improve Providing nitrogen 70, 73, 299 training for bottles as loss of air accumulators for Restore AFW control after plant trip selected valves following initiator and would reduce action loss of air, low 3.70E-03 difficulty dependence on HAOB2 HAERCW3 Improve Procedure (AOI-13) 45, 46,53, training to already available for 54,56, 62,64, align and loss of ERCW. 155, 156 initiate cooling Enhance training to from fire improve chances of protection success.

system to 2A-A or 2B-B CCPs when ERCW (and CCS) fails Recovery Sequence 7 (Common Cause of DG XSBO15 1.37E-01 1.027 - See %0LOSP-GR - to Start) WI See probability that 1 or more are Probability that 0 U2_0BLOCK 7.50E-01 1.027 N/A blocked - PORVs are blocked

- See -

DGGFR2GEN_0822 DG 1B-B FAILS TO DGGFR1GEN_0821B-B 1.46E-02 1.027 A-A RUN

- See - DIESEL GENERATOR DGGFR2GEN_0822 2A-A FAILS TO START DGGFD2GEN_0822A-A 6.88E-03 1.026 A-A AND RUN FIRST HOUR 24

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description

- See - DIESEL GENERATOR DGGFR2GEN_0822 FAILS TO START AND A-A RUN FIRST HOUR (WBN-2-GEN -082-DGGFD2GEN_0822B-B 6.88E-03 1.024 0002B -B)

- See -

DGGFR2GEN_0822 DIESEL 2B-B MTM_2GEN_0822B-B 1.07E-02 1.024 A-A MAINTENANCE Improve Pump improvements 46, 53, 56, reliability of already 62, 155, 158, ERCW pumps implemented. 271 or limit the SAMAs identified to potential for limit dependence on seal LOCAs ERCW given the CCF OF ALL ERCW U0_ERCW_PMP_FR_CCF ERCW PUMPS FAILS TO

_IE_ALL 6.32E-05 1.022 system is lost RUN IE Improve Procedure (AOI-13) 45, 46,53, training to already available for 54,56, 62,64, align and loss of ERCW. 155, 156 initiate cooling Enhance training to from fire improve chances of protection success.

system to 2A-A or 2B-B OPERATOR FAILS TO CCPs when ALIGN EXISTING FIRE ERCW (and PROTECTION PUMP HAERCW3 5.00E-02 1.022 CCS) fails TO CCP 2A-A For multiplier of 2.28 1.022 25

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Reduce Reduce challenges 136, 137, CCF of two probability of to plant trip or 218 components:

reactor trip provide alternate RTBFO2RTB_0990000 failure means to trip reactor A&

U2_RPS_RT__RTB_FO_C RTBFO2RTB_0990000 CF_1_2 3.33E-06 1.021 B Improve Provide procedure 73, 299 Blind Feed DGs training for for local control Recovery manual steam when control power generator is lost for station level control blackout and non station blackout HAOSBF 2.00E-01 1.021 sequences U1_250BATTDEP 1.00E+00 1.021 - Flag event -

HRADEP-POST-128 9.90E-05 1.02 HACH1 Improve Goal is to reduce 35, 91, operator error rate to transfer 92,105, performance containment spray 106,107,306 by enhancing pumps to sump, likelihood of (HACH1) given recovery from successful RHR execution swap over to the errors sump 26

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description HARR1 Improve Existing EOPs 31,32, 34,36, operator provide directions 187,238, performance for monitoring and 247,299 and minimize conserving water in need for the containment manual action recirculation sump.

to complete These procedures high pressure are already used recirculation extensively in alignment license operator initial training and license operator continuing training programs, and are practiced in the plant simulator.

AFWOP3 Improve Sequence involves 299 operator need to performance depressurize and by enhancing cooldown the RCS likelihood of for LPI following a recovery from small LOCA with execution failure of high errors pressure recirculation.

Numerous critical steps with limited recovery of slips or omissions 27

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve Provide a 86, 188,279, availability of permanent tie-in to 280, 281 air system. the construction air compressor, or add new Unit 2 air compressor similar to the Unit 1 D compressor, or replace the ACAS COMPRESSOR A-A compressors and FAILS TO RUN WBN CMPSR0COMP03200060 6.29E-02 1.02 dryers. 32-60 Improve Improve recovery 330 reliability of from failure of high stress execution step (4 action to hours available after isolate the alarm 167-D) which HPFP break dominates error Isolate break in HPFP in the rate. line (supplied by RCW -

auxiliary HPFP diesel pump does FLAB4F 1.30E-01 1.019 building. not start Flood event induced by HPFP in the common areas of the Auxiliary

%0FLHPFPABF 5.49E-04 1.019 - See FLAB4F 330 Building see COMPRESSOR B-B CMPSR0COMP032 FAILS TO RUN WBN CMPSR0COMP03200086 6.29E-02 1.019 - 00060 - 32-86 HRADEP-POST-180 9.70E-05 1.019 28

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Add recovery step for execution error in Reduce starting ERCW execution pump error of failure (HAAEIE=1.8E-3) in to start response to 2 Start standby ERCW standby ERCW pumps failing pump - operating pump HAAEIE 1.80E-03 ERCW pump to run 331 fails - normal ops Improve Providing nitrogen 70, 73, 299 training for bottles as Restore AFW control loss of air accumulators for following initiator and after plant trip selected valves loss of air, (when ERCW would reduce action failed), low dependence HAFR1 3.70E-03 difficulty with HAAEIE Reduce frequency of Improve reliability of

%2TTIE 2.32E-01 1.018 turbine trip power supplies. 218 Turbine Trip

- See -

DGGFR2GEN_0822 DIESEL 1B-B MTM_1GEN_0821B-B 1.22E-02 1.018 A-A MAINTENANCE Provide for improved credit to be taken for loss of HVAC sequences, BOARD ROOM especially for EXHAUST FAN FAILS the DG open doors or use TO START OR RUN electric board adjacent room's FIRST HOUR, on DG FNSFD1FAN_030461 9.13E-03 1.017 rooms exhaust fans 160, 246 1B-B 29

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve training and annunciating to reduce failure probability to terminate inadvertent safety injections Training already prior to water conducted on Terminate Safety challenge to inadvertent Safety 8,292, 299, Injection to prevent SSIOP 6.70E-03 1.017 PORVs Injection (SI), 306 PORV water challenge 30

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description HRADEP-POST-309 2.50E-05 1.016 Improve training and annunciating to reduce failure probability to terminate inadvertent safety injections Training already prior to water conducted on Terminate Safety challenge to inadvertent Safety 8,292, 299, Injection to prevent SSIOP 6.70E-03 PORVs Injection (SI), 306 PORV water challenge Improve Existing EOPs 31,32, 34,36, operator provide directions 187,238, performance for monitoring and 247,299 and minimize conserving water in need for the containment manual action recirculation sump.

to complete These procedures high pressure are already used recirculation extensively in alignment license operator initial training and license operator Align high pressure continuing training recirculation, given auto programs, and are swap over works, practiced in the plant medium dependence on HARR1 3.80E-03 simulator. SSIOP 31

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description SPARE CHARGER FL_SPARE_250_CHGR_N NOT ALIGNED FOR A OT_A 1.00E+00 1.016 - Flag event - TRAIN Reduce fraction of time charging pump in maintenance Reschedule CCP WBN-2-PMP-062-0108-while plant is maintenance to A CCP 1A-A IN MTM_2PMP_0620108A 3.78E-03 1.015 at power shutdown conditions 328 MAINTENANCE SECONDARY BREAK OUTSIDE

%2SSBO-1 2.50E-03 1.014 CONTAINMENT SG 1 Improve Training already 8, 292,299 training and conducted on annunciating inadvertent Safety to reduce Injection (SI),

failure probability to terminate inadvertent safety injections prior to water challenge to Failure to terminate SI PORVs 32

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve Existing EOPs 31,32, 34,36, operator provide directions 187,238, performance for monitoring and 247,299 and minimize conserving water in need for the containment manual action recirculation sump.

to complete These procedures high pressure are already used recirculation extensively in alignment license operator initial training and license operator continuing training Failure to align for high programs, and are pressure recirculation from practiced in the plant the sump, HARR1 simulator.

SECONDARY BREAK OUTSIDE

%2SSBO-4 2.50E-03 1.014 - see %2SSBO-1 CONTAINMENT SG 4 SECONDARY BREAK OUTSIDE

%2SSBO-2 2.50E-03 1.014 - see %2SSBO-1 CONTAINMENT SG 2 SECONDARY BREAK OUTSIDE

%2SSBO-3 2.50E-03 1.014 - see %2SSBO-1 CONTAINMENT SG 3 CCF pump failure CCF of two Reduce CCF probability not components:

failure measurably affected PMAF12PMP_0030011 probability of by procedures, 8&

U2-AFW-TOT-PMA-FD- MD AFW training, nor PMAF12PMP_0030012 CCF_1_2 4.04E-04 1.014 pump indications None 8 33

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description

- See -

DGGFR2GEN_0822 DG 1A-A FAILS TO DGGFR1GEN_0821A-A 1.46E-02 1.014 A-A RUN Random pump failure not measurably affected by procedures, training, nor PUMP FAILS AFTER 1 PTSFR2PMP_003001AS 1.76E-03 1.013 - indications None HOUR WBN-2-3-1AS Reduce operator action error to recover from turbine building flood with Recovery actions independent addresses with failure of action group Major flood in the

%0FLTBMF 8.58E-03 1.013 ACAS. HRADEP-POST-221 None Turbine Building

- See - DG 1B-B FAILS TO DGGFR2GEN_0822 START AND RUN DGGFD1GEN_0821B-B 6.88E-03 1.013 A-A FIRST HOUR 34

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Reduce Action is called for in frequency of procedures and losing all PRA model already AFW caused considers action to when all room restore AFW under cooling is lost Station blackout to TD AFW conditions (HAAF1) pump. when local manual Operator control is required.

action to open However, only credit room for offsite power DC EMERG EXHAUST containing recovery is FAN FAILS TO START AFW pump conservatively AND RUN FOR 1ST should modeled when this Already HOUR WBN-2-30-214, FNSFD2FAN_03000214 9.13E-03 1.012 suffice. fan also fails. implemented for TD AFW pump room Reduce time fraction that Basic plant design pressure relief cannot be changed requires 3 by revising SVs and 2 procedures, PORVs additional training, Interval 2 for PRA (pres during an nor additional relief requires 3 SVs & 2 PRAI2 1.70E-01 1.012 ATWS indications. None PORVs)

- See -

DGGFR2GEN_0822 SEQUENCER 2A-A SEQFD2A-A 3.33E-03 1.012 A-A FAILS (Unknown UNID)

Reduce frequency of Improve reliability of

%2RTIE 2.85E-01 1.012 reactor trip power supplies. 218 Reactor Trip 35

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve Enhanced training or procedures already revise implemented, procedure to additional training establish feed could reduce error and bleed rate cooling given Establish RCS Bleed no CCPs are 283, 285, and Feed cooling given HAOB2 1.60E-02 1.012 running 299, 300 no CCPS running Refurbish the Improves the 271 ERCW pumps reliability of the CCF of all components

& upgrade the ERCW pumps. in group capacity of 'U0_ERCW_TS_PL_CC U0_ERCW_TS_PL_CCF_I the current F_IE', 2 MD AFW E_ALL 6.73E-04 1.011 pumps. pumps

%2LVBB4 1.00E+00 1.011 Loss of Battery Board 4 Loss of AFW given battery Improve Additional training 284,286 board fails training for may reduce isolation MD AFW error rate pump trains A and B and for TD AFW pump isolation tests Feed and bleed cooling Improve Enhanced 285, 283 fails given battery board training to procedures already fails establish feed implemented, and bleed additional training cooling given could reduce error battery board rate lost 36

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Failure of high pressure Improve Existing EOPs 31,32,34,36, recirculation during feed operator provide directions 187,238,247 and bleed with battery performance for monitoring and board lost and minimize conserving water in need for the containment manual action recirculation sump.

to complete These procedures high pressure are already used recirculation extensively in alignment license operator initial training and license operator continuing training programs, and are practiced in the plant simulator.

- See -

DGGFR2GEN_0822 SEQUENCER 2B-B SEQFD2B-B 3.33E-03 1.011 A-A FAILS (Unknown UNID)

Random pump and valve failures not measurably affected by procedures, training, nor Partial Loss of Main

%2PLMFW 1.46E-01 1.011 - indications None Feedwater 37

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description

- See None DGGFR2GEN_0822 A-A, opening room doors is not CCF of all components sufficient to in group U0_EPS_VDG_FAN_FD2_ adequately cool the 'U0_EPS_VDG_FAN_F CCF_ALL 1.62E-04 1.011 DG room D2_CCF' Add procedures PRA assumes room and perform cooler is required analysis to (cooled by ERCW) justify that for pump operation.

CCP room Opening door to may be CCP room is not adequately included in the PRA cooled by just nor yet verified to be opening doors effective at keeping CCP A ROOM COOLER when room temperatures FAN FAILS DURING FNSFR2FAN_03000183 2.66E-03 1.011 cooling is lost. acceptable 337 OPERATION Reduce fraction of time CAS compressor D in Reschedule CAS maintenance compressor D CAS COMPRESSOR D while plant is maintenance to IN MAINTENANCE MTM_0CAD03204900 3.30E-02 1.011 at power shutdown conditions 329 WBN-0-32-COMP-4900 Recovery Sequence 4 (DG A And B Fail to Start And TDAFW Fails XSBO12 9.31E-01 1.011 - See %0LOSP-GR - to Start) WI 38

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve Providing nitrogen 70, 73,299 training for bottles as loss of air accumulators for after plant trip selected valves would reduce action difficulty. Current PRA model gives no credit for action to cope with loss of air, but procedures Major flood event apply equally well to induced by RCW in the flood induced common areas of the

%0FLRCWABMF 3.94E-05 1.01 losses. Auxiliary Building (

Secondary contributor to loss of ERCW initiating event; see responses for ERCW PUMP A-A

%0TLERCW, FAILS TO HAAEIE, and RUNINITIATING POEFR0PMP_06700028IE 2.97E-02 1.01 - HAERCW3 - EVENT WBN-0-67-28 Secondary contributor to loss of ERCW initiating event; see responses for ERCW PUMP C-A

%0TLERCW, FAILS TO RUN HAAEIE, and INITIATING EVENT POEFR0PMP_06700036IE 2.97E-02 1.01 - HAERCW3 - WBN-0-67-36 39

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Secondary contributor to loss of ERCW initiating event; see responses for ERCW PUMP E-B

%0TLERCW, FAILS TO RUN CC 1/4 HAAEIE, and INITIATING EVENT POEFR0PMP_06700047IE 2.97E-02 1.01 - HAERCW3 - WBN-0-67-E-B Secondary contributor to loss of ERCW initiating event; see responses for ERCW PUMP G-B

%0TLERCW, FAILS TO HAAEIE, and RUNINITIATING POEFR0PMP_06700055IE 2.97E-02 1.01 - HAERCW3 - EVENT WBN-0-67-55

- See None DGGFR2GEN_0822 A-A, opening room doors is not sufficient to EXHAUST FAN FAILS adequately cool the TO START OR RUN FNSFD2FAN_030448 9.13E-03 1.01 DG room FIRST HOUR

- See None DGGFR2GEN_0822 A-A, opening room doors is not sufficient to EXHAUST FAN FAILS adequately cool the TO START OR RUN FNSFD2FAN_030452 9.13E-03 1.01 DG room FIRST HOUR 40

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Recovery Sequence 8 (Common Cause of DG to Start AND TDAWF XSBO18 9.31E-01 1.01 - See %0LOSP-GR - Fails to Start) WI Reduce time Basic plant design fraction that cannot be changed pressure relief by revising requires 3 procedures, SVs and 1 additional training, Interval 3 for PRA (pres PORV during nor additional relief requires 3 SVs & 1 PRAI3 1.50E-01 1.01 an ATWS indications. None PORV)

Basic plant design Improve cannot be changed reliability of by revising 6.9kv circuit procedures, 6.9kV SDBD BREAKER breaker to SD additional training, 1816 FAILS TO OPEN, CBKFO2BKR_2111816/16 BD to open nor additional required for power from

-A 2.55E-03 1.009 on demand indications. None EDG Basic plant design cannot be changed by revising procedures, Reduce additional training, potential for nor additional failing to open indications. Local WBN-1-RFV-062-0636-on demand action to open S RELIEF VALVE the common breaker would be FAILS TO OPEN on relief valve on too late to achieve common seal injection RLVFO2RFV_0620636 2.47E-03 1.009 seal return success. None return line HRADEP-POST-289 1.10E-02 1.009 41

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Action error rate Improve dominated by operator execution steps performance which are already by improving well documented in procedures ES-1.2, though high and training stress is postulated for completing for the medium RCS LOCA. High depressurizati dependence on during a assumed between medium execution steps and LOCA to occurrence of allow low feedback to Depressurize/cooldown pressure operators for to low pressure injection AFWOP1 2.10E-02 injection recovery. 338 following MLOCA 42

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve Existing EOPs 31,32, 34,36, operator provide directions 187,238, performance for monitoring and 247,299 and minimize conserving water in need for the containment manual action recirculation sump.

to complete These procedures high pressure are already used recirculation extensively in alignment license operator initial training and license operator Align high pressure continuing training recirculation, given auto programs, and are swap over works; high practiced in the plant dependence on HARR1 3.80E-03 simulator. AFWOP1 Reduce CCF probability of multiple Basic plant design safeguard cannot be changed CCF of two driver cards by revising components:

resulting in procedures, SGDCF2SGD_099A517 loss of additional training, A&

U2_ESF_SGD_CF_517_C actuation nor additional SGDCF2SGD_099A517 CF_1_2 9.32E-05 1.009 signals indications. None B

- See -

DGGFR2GEN_0822 DIESEL 1A-A MTM_1GEN_0821A-A 1.10E-02 1.009 A-A MAINTENANCE 43

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description BOARD ROOM EXHAUST FAN FAILS FNSFD1FAN_03046 TO START OR RUN FNSFD1FAN_030459 9.13E-03 1.009 1 FIRST HOUR, DG 1A-A Basic plant design cannot be changed by revising Improve procedures, 125V DC VITAL reliability of additional training, BATTERY BOARD IV DC bus to nor additional FAILS DURING BUSFR0BD__2364G_IE 3.80E-03 1.009 operate indications. None OPERATION Loss of Component Cooling System Train

%2CCS2A 1.00E+00 - See %2CCS - 2A HRADEP-POST-220 2.40E-03 1.009 Improve Can provide manual alternate means to actions to re- establish secondary establish heat removal or secondary improve training and heat removal procedures to or initiate respond to loss of bleed and actuation signal feed cooling when automatic Perform cooldown with actuation of 66,68, 276, main feedwater, HACD1 AFW fails 296, 299 following AFW failure Start AFW (Reactor trip, no SI), medium HAOS3 dependence on HACD1 44

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Goal is to Enhanced 79, 283,285, reduce error procedures already 300 rate for implemented, operator additional training action to could reduce error Establish RCS Bleed initiate feed rate and Feed cooling given and bleed no CCPS running, high HAOB2 cooling dependence on HAOS3 HRADEP-POST-218 5.40E-03 1.009 Improve Can provide manual alternate means to actions to re- establish secondary establish heat removal or secondary improve training and heat removal procedures to or initiate respond to loss of bleed and actuation signal feed cooling when automatic Perform cooldown with actuation of 66,68, 276, main feedwater, HACD1 3.24E-02 AFW fails 296, 299 following AFW failure Goal is to Enhanced 79, 283,285, reduce error procedures already 300 rate for implemented, operator additional training Establish RCS Bleed action to could reduce error and Feed cooling given initiate feed rate no CCPS running, and bleed medium dependence on HAOB2 1.60E-02 cooling HACD1 45

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve Existing EOPs 31,32, 34,36, operator provide directions 187,238, performance for monitoring and 247,299 and minimize conserving water in need for the containment manual action recirculation sump.

to complete These procedures high pressure are already used recirculation extensively in alignment license operator initial training and license operator continuing training programs, and are Align high pressure practiced in the plant recirculation, given auto HARR1 3.80E-03 1.009 simulator. swap over works Basic plant design Improve cannot be changed reliability of by revising 6.9kv circuit procedures, 6.9kV SDBD BREAKER breaker to SD additional training, 1828 FAILS TO OPEN, CBKFO2BKR_2111828/16 BD to open nor additional required for power from

-B 2.55E-03 1.009 on demand indications. None EDG 46

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Flood event None induced by break of HPFP line in room 757.0-A2 propagates to Basic plant design all 4 6.9kv cannot be changed shutdown by revising boards procedures, causing additional training, Flood event induced by station nor additional break of HPFP line in

%0FLHPFPAB757A2 1.44E-07 1.008 blackout indications. room 757.0-A2 HRADEP-POST-305 1.30E-05 1.008 Sequence involves

%SSBO-1,2,3,4 with failure to terminate SI prior to PZR Reduce PORV water likelihood that challenge; Modify operators procedures to reset SI signal ensure that failing sump operators confirm auto-swap that no RCS leakage over by occurs once PORV including is challenged to execution minimize chance of Inadvertently Reset SI recovery step inadvertently Signal, Failure of Auto HCRL1 3.80E-03 in procedures resetting SI signal. 333 Sump Swap over 47

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve training and annunciating to reduce failure probability to terminate inadvertent safety Terminate Safety injections Training already Injection to prevent prior to water conducted on PORV water challenge, challenge to inadvertent Safety 8,292, 299, high dependence on SSIOP 6.60E-03 PORVs Injection (SI), 306 HCRL1 Human error rate conservatively evaluated assuming timing for a large Improve LOCA. Much procedures to greater time include available for recovery from secondary side Recover from auto swap execution breaks with stuck over failure, medium HARL1 2.30E-03 errors open PZR PORV 334 dependence on SSIOP

- See - CCF of two DGGFR2GEN_0822 components:

A-A DGGFR1GEN_0821B-B U0_EPS_GA_GEN_FR_C &

CF_2_3 3.59E-04 1.008 DGGFR2GEN_0822A-A 48

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Provide for open doors or use 160, 246 improved adjacent room's credit to be exhaust fans; taken for loss already of HVAC implemented at sequences, Watts Bar especially for the DG EXHAUST FAN FAILS electric board TO START OR RUN FNSFD2FAN_030450 9.13E-03 1.008 rooms FIRST HOUR Provide for open doors or use 160, 246 improved adjacent room's credit to be exhaust fans; taken for loss already of HVAC implemented at sequences, Watts Bar especially for the DG EXHAUST FAN FAILS electric board TO START OR RUN FNSFD2FAN_030454 9.13E-03 1.008 rooms FIRST HOUR Total Loss of Plant

%0TLPCA 9.81E-03 1.008 - See HAFR1 - Compressed Air HRADEP-POST-171 2.10E-04 1.008 Action is to start selected pump to Reduce allow traveling execution screen to rotate at error rate by least one full adding revolution, for 20 Operators fail to clear recovery step minutes or until no ERCW screens before DHAERCWS 3.80E-03 to procedures longer needed 332 plant trip 49

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve Providing nitrogen 70, 73,299 training for bottles as Restore AFW control loss of air accumulators for following initiator and after plant trip selected valves loss of air, low would reduce action dependence on HAFR1 3.70E-03 difficulty DHAERCWS Provide for open doors or use 160, 246 improved adjacent room's credit to be exhaust fans; taken for loss already of HVAC implemented at sequences, Watts Bar especially for the DG electric board EXHAUST FAN 2-FAN-FNSFR2FAN_030460 2.66E-03 1.008 rooms30-460 FAILS TO RUN Add procedures PRA assumes room and perform cooler is required analysis to (cooled by ERCW) justify that for pump operation.

CCP room Opening door to may be CCP room is not adequately included in the PRA cooled by just nor yet verified to be opening doors effective at keeping when room temperatures CCP A ROOM COOLER MTM_2FAN_03000183 2.00E-03 1.008 cooling is lost. acceptable 337 FAN IN MAINTENANCE 50

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Add procedures PRA assumes room and perform cooler is required analysis to (cooled by ERCW) justify that for pump operation.

CCP room Opening door to may be CCP room is not adequately included in the PRA cooled by just nor yet verified to be opening doors effective at keeping when room temperatures CCP A ROOM COOLER TTM_2FAN_03000183 2.00E-03 1.008 cooling is lost. acceptable 337 FAN IN TEST See CMPSR0COMP032 CAS COMPRESSOR A 00060 FAILS TO RUN WBN CMPSR0COMP03200025 6.29E-02 1.008 - and HAFR1 - 32-25 See CMPSR0COMP032 COMPRESSOR B 00060 FAILS TO RUN WBN CMPSR0COMP03200026 6.29E-02 1.008 - and HAFR1 - 32-26 Reduce Reduce challenges 136, 137,218 probability of to plant trip or reactor trip provide alternate Manually trip reactor, HART1 1.40E-03 1.008 failure means to trip reactor given SSPS fails 51

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Flood event None induced by rupture of RCW line in room 757.0-A17 propagates to Basic plant design all 4, 6.9kv cannot be changed shutdown by revising boards procedures, causing additional training, Flood event induced by station nor additional rupture of RCW line in

%0FLRCW757A17 1.27E-07 1.007 blackout indications. room 757.0-A17 Flood event None induced by rupture of RCW line in room 757.0-A9 propagates to Basic plant design all 4, 6.9kv cannot be changed shutdown by revising boards procedures, causing additional training, Flood event induced by station nor additional rupture of RCW line in

%0FLRCW757A9 1.27E-07 1.007 blackout indications. room 757.0-A9 ALIGN PORTABLE DIESEL GENERATOR TO SHUTDOWN XSBO25 5.00E-01 1.007 - See %0LOSP-GR - BOARD 2B-B 52

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description CCF of all components in group U0_ERCW_PMP_FR_CCF 'U0_ERCW_PMP_FR_

_ALL 3.88E-06 1.007 - See %0TLERCW - CCF' CCP 1B-B ROOM See COOLING FAN FAILS FNSFR2FAN_03000 TO START AND RUN FNSFD2FAN_03000182 9.13E-03 1.007 - 183 - FOR FIRST HOUR Reduce error rate for operators failing to restart an Residual Heat Removal (RHR) pump for HP recirculation Revise procedures from the and training to OPERATOR FAILS TO sump after address this human RESTART RHR PUMP previously action (DHARR3 = FOR HP DHARR3 1.00E-03 1.007 securing SI. 1E-3). 336 RECIRCULATION CCF of two components:

CMPSR0COMP032000 See 60 &

U0_032_ACAS_CMP_FR_ CMPSR0COMP032 CMPSR0COMP032000 CCF_1_2 3.25E-03 1.007 - 00060 - 86 See FNSFR2FAN_03046 EXHAUST FAN 2-FAN-FNSFR2FAN_030462 2.66E-03 1.007 - 0 - 30-462 FAILS TO RUN 53

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Biggest contributors from steam line breaks leading to stuck open PZR PORVs' i.e., smaller LOCAs. Basic plant design cannot be Reduce changed by revising probability of procedures, sump additional training, strainers nor additional plugging indications. Local precluding action to open recirculation breaker would be SUMP SUCTION from the too late to achieve STRAINERS PLUGGED SMPPL2STN_SUMP1 1.00E-03 1.007 sump success. None (LLOCA OR MLOCA)

- See - DG 1A-A FAILS TO DGGFR2GEN_0822 START AND RUN DGGFD1GEN_0821A-A 6.88E-03 1.007 A-A FIRST HOUR Sequence leads to loss of CCS with seal LOCA and fails recirculation from sump due to multiple operator actions (HRADEP-POST-A1). Consider WBN-2-HTX-070-0185 improvements to Hardware CCS HEAT HXRPL2HTX_07000185IE associated human fixes not cost EXCHANGER A T 5.65E-03 1.007 actions below effective PLUGGING 54

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description ALIGN AND INITIATE ALTERNATE COOLING HCCSR2 1.60E-02 - See HCCSR2 - TO CCP 2A-A Transfer Containment Spray to Sump (RHR HACH1 1.10E-02 - See %2SLOCAL - Swap Successful)

Depressurize/cooldown to low pressure injection following small LOCA AFWOP3 1.10E-02 - See %2SLOCAL - with failure HRADEP-POST-B7 7.61E-03 1.007 Improve training and procedures to cross-connect fire protection pump flow to ERCW in the event ERCW pumps all fail as initiating event with power from Procedure MA-1, OPERATOR FAILS TO shutdown Rev 3, Appendix C ALIGN FIRE boards details the steps to PROTECTION PUMP HAERCW2 7.80E-02 available follow. 335 TO ERCW HEADER 55

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Improve Procedure (AOI-13) 45, 46,53, training to already available for 54,56, 62,64, align and loss of ERCW. 155, 156 initiate cooling Enhance training to from fire improve chances of OPERATOR FAILS TO protection success. ALIGN EXISTING FIRE system to 2A- PROTECTION PUMP A or 2B-B TO CCP 2A-A, low CCPs when dependence on ERCW (and HAERCW2 performed HAERCW3 5.00E-02 CCS) fails within minutes Not Training or HRA AOV FAILS TO CLOSE AOCFC0PCV_03300004 7.39E-04 1.006 N/A related ON DEMAND WBN-0-33-4 Not Training or HRA CONTROL RODS FAIL CRI 1.20E-06 1.006 N/A related TO INSERT DC EMERGENCY EXHAUST FAN FAILS TO Not Training or HRA RUN AFTER 1ST HOUR FNSFR2FAN_03000214 2.66E-03 1.006 N/A related WBN-2-30-214 Flood event induced by Not Training or HRA break of HPFP line in room

%0FLHPFPAB757A24 1.07E-07 1.006 N/A related 757.0-A24 56

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description HRADEP-POST-293 2.10E-04 1.006 Failure of high pressure Improve Existing EOPs 31,32, 34,36, recirculation from the operator provide directions 187,238, sump, HARR1 performance for monitoring and 247,299 and minimize conserving water in need for the containment manual action recirculation sump.

to complete These procedures high pressure are already used recirculation extensively in alignment license operator initial training and license operator continuing training programs, and are Align high pressure practiced in the plant recirculation, given auto simulator. swap over works HAFR1 Improve Providing nitrogen 70, 73, 299 training for bottles as loss of air accumulators for Restore AFW control after plant trip selected valves following initiator and would reduce action loss of air, low 3.70E-03 difficulty dependence on HAOB2 57

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description HRADEP-POST-193 3.1E-05 1.006 Failure of high pressure Improve Existing EOPs 31,32, 34,36, recirculation from the operator provide directions 187,238, sump, HARR1 performance for monitoring and 247,299 and minimize conserving water in need for the containment manual action recirculation sump.

to complete These procedures high pressure are already used recirculation extensively in alignment licensed operator initial training and license operator continuing training programs, and are Align high pressure practiced in the plant recirculation, given auto simulator. swap over works Depressurize/cooldown to low pressure injection following small LOCA AFWOP3 1.10E-02 - See %2SLOCAL - with failure 58

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Makeup to RWST using Improve containment spray test Cognitive contribution operator is 3.1E-03, Execution recirculation from the performance is 1.9E-03. Procedure containment sump HAMU2B 5E-03 via training ECA-1.1 governs 340 (New) during a small LOCA BLOCK VALVE CLOSED Not Training or HRA TO ISOLATE LEAKING XPORV1 5.29E-02 1.006 N/A related PORV CCF of all components in group U0_EPS_GA_GEN_FD_CCF Not Training or HRA 'U0_EPS_GA_GEN_FD_C

_ALL 9.01E-05 1.006 N/A related CF' SAFETY VALVE FAILS TO RESEAT AFTER Not Training or HRA STEAM RELIEF WBN SRVSR2SRV_06800563 7.95E-04 1.006 N/A related 68-563 SAFETY VALVE FAILS TO RESEAT AFTER Not Training or HRA STEAM RELIEF WBN SRVSR2SRV_06800564 7.95E-04 1.006 N/A related 68-564 SAFETY VALVE FAILS TO RESEAT AFTER Not Training or HRA STEAM RELIEF WBN SRVSR2SRV_06800565 7.95E-04 1.006 N/A related 68-565 59

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Isolate CCW following Not Training or HRA major break in Turbine FLTB1C 1.00E-02 1.006 N/A related Building Not Training or HRA Total Loss of Main

%2TLMFW 7.01E-02 1.006 N/A related Feedwater Not Training or HRA SEQUENCER 1B-B FAILS SEQFD1B-B 3.33E-03 1.006 N/A related (Unknown UNID)

Not Training or HRA EXCESSIVE LOCA

%2EX 1.00E-07 1.006 N/A related (VESSEL RUPTURE)

Not Training or HRA COMPRESSOR C FAILS CMPSR0COMP03200027 6.29E-02 1.006 N/A related TO RUN WBN-0-32-27 Not Training or HRA Loss of Condenser

%2LOCV 6.53E-02 1.006 N/A related Vacuum 60

Table 4ai-1 Review of Basic Events with RRW Greater than 1.006 to CDF for Potential New RAI SAMAs (Continued)

Red Event Name Probability W SAMA Title SAMA Discussion SAMA # Description Not Training or HRA PUMP WBN-2-3-128-B IN MTM_2PMP00300128 4.22E-03 1.006 N/A related MAINTENANCE PUMP FAILS TO START Not Training or HRA AND RUN FOR 1 HOUR PMAF12PMP_00300118 2.89E-03 1.006 N/A related WBN-2-3-118-A Not Training or HRA PUMP WBN-2-3-118-A IN MTM_2PMP00300118 3.84E-03 1.006 N/A related MAINTENANCE for Multiplier of 1.006 2.28 61

Table 2.a.iv-7.

RAI Revised Base Cost Comparison October 2010, Revised (RAI) Sept

% Change SAMA Report 2011 SAMA Results Base Cost with External Event $3,309,176 $3,860,606 + 17%

Muliplier 2.0 Base Cost with External Event $3,772,461 $4,401,090 + 17%

Multiplier 2.28 62

Table 2.a.iv RAI Revised SAMA Phase II Analysis Results Revised September, 2011 SAMA RAI Results Revised September, 2011 SAMA RAI Results (External Events Multiplier = 2.0) (External Events Multiplier = 2.28)

Benefit/ Benefit/

SAMA Estimated Estimated Cost Change in Estimated Estimated Cost Change in No. SAMA Title Benefit Cost Ratio Conclusion Benefit Cost Ratio Conclusion Already Already committed committed to do, to do, see January, Improve DC bus load see Jan.,2009t 2009SAMA 4 shedding. $35,111 $31,675 1.11 SAMA submittal $40,026 $31,675 1.26 submittal Already Increase training on response committed to do, Already committed to loss of two 120V AC buses see January, to do, see January, which causes inadvertent 2009 SAMA 2009 SAMA 8 actuation signals. $10,949 $26,773 0.41 submittal $12,482 $26,773 0.47 submittal Provide an additional high pressure injection pump with 26 independent diesel. $57,181 $3,571,000 0.02 Not cost beneficial $65,186 $3,571,000 0.02 Not cost beneficial Add the ability to automatically align emergency core cooling system to recirculation mode upon refueling water storage 32 tank depletion. $351,587 $2,100,000 0.17 Not cost beneficial $400,809 $2,100,000 0.19 Not cost beneficial Enhance procedural guidance for use of cross-tied component cooling or service 45 water pumps. $4,562 $31,675 0.14 Not cost beneficial $5,201 $31,675 0.16 Not cost beneficial 46 Add a service water pump. $129,763 $1,042,511 0.12 Not cost beneficial $147,930 $1,042,511 0.14 Not cost beneficial Install an independent reactor coolant pump seal injection system, without dedicated 56 diesel. $1,080,157 $8,233,000 0.13 Not cost beneficial $1,231,379 $8,233,000 0.15 Not cost beneficial Install accumulators for turbine-driven auxiliary feedwater pump flow control 70 valves. $88,566 $256,204 0.35 Not cost beneficial $100,966 $256,204 0.39 Not cost beneficial Install a new condensate storage tank (auxiliary 71 feedwater storage tank). $0 $1,706,586 0.00 Not cost beneficial $0 $1,706,586 0.00 Not cost beneficial 63

Table 2.a.iv RAI Revised SAMA Phase II Analysis Results (Continued)

Revised September, 2011 SAMA RAI Results Revised September, 2011 SAMA RAI Results (External Events Multiplier = 2.0) (External Events Multiplier = 2.28)

Benefit/ Benefit/

SAMA Estimated Estimated Cost Change in Estimated Estimated Cost Change in No. SAMA Title Benefit Cost Ratio Conclusion Benefit Cost Ratio Conclusion Replace service and instrument air compressors with more reliable compressors which have self-contained air 87 cooling by shaft driven fans. $1,908 $886,205 0.00 Not cost beneficial $2,175 $886,205 0.00 Not cost beneficial 93(See Install an unfiltered, Note 1) hardened containment vent. $1,089,701 $3,100,000 0.35 Not cost beneficial $1,242,259 $3,100,000 0.40 Not cost beneficial Provide a reactor vessel 101 exterior cooling system. $182,392 $2,500,000 0.07 Not cost beneficial $207,927 $2,500,000 0.08 Not cost beneficial Not cost beneficial, Cost Not cost beneficial, includes new Cost includes new Institute simulator training for software and software and 103 severe accident scenarios. $1,229,070 $8,000,000 0.15 hardware upgrade $1,401,139 $8,000,000 0.18 hardware upgrade Install a passive hydrogen 109 control system. $265,139 $3,736,000 0.07 Not cost beneficial $302,259 $3,736,000 0.08 Not cost beneficial Erect a barrier that would provide enhanced protection of the containment walls (shell) from ejected core debris following a core melt scenario 110 at high pressure. $90,783 $1,151,000 0.08 Not cost beneficial $103,493 $1,151,000 0.09 Not cost beneficial Add redundant and diverse limit switches to each 112 containment isolation valve. $2,815 $691,524 0.00 Not cost beneficial $3,210 $691,524 0.00 Not cost beneficial Install motor generator set trip 136 breakers in control room. $11,679 $241,795 0.05 Not cost beneficial $13,315 $241,795 0.06 Not cost beneficial Proposed procedure change Proposed procedure Eliminate RCP thermal barrier ineffective. See change ineffective.

dependence on CCW, such Section 10 of See Section 10 of that loss of CCW does not Oct., 2010 SAMA Oct., 2010 SAMA 156 result directly in core damage. $686,176 $31,675 21.66 report $782,241 $31,675 24.70 report 64

Table 2.a.iv RAI Revised SAMA Phase II Analysis Results (Continued)

Revised September, 2011 SAMA RAI Results Revised September, 2011 SAMA RAI Results (External Events Multiplier = 2.0) (External Events Multiplier = 2.28)

Benefit/ Benefit/

SAMA Estimated Estimated Cost Change in Estimated Estimated Cost Change in No. SAMA Title Benefit Cost Ratio Conclusion Benefit Cost Ratio Conclusion Provide a connection to 176 alternate offsite power source. $686,153 $9,126,460 0.08 Not cost beneficial $782,214 $9,126,460 0.09 Not cost beneficial Provide self-cooled ECCS 191 seals. $0 $1,000,000 0.00 Not cost beneficial $0 $1,000,000 0.00 Not cost beneficial Not cost Not cost beneficial; beneficial; first of first of a kind Provide a means to ensure a kind installation; installation; RCP seal cooling so that RCP downside impacts downside impacts seal LOCAs are precluded for on risk impact not on risk impact not 215 SBO events. $1,153,970 $1,500,000 0.77 assessed $1,315,525 $1,500,000 0.88 assessed Permanent, self- powered pump to backup normal 226 charging pump. $1,153,970 $2,700,000 0.43 Not cost beneficial $1,315,525 $2,700,000 0.49 Not cost beneficial Permanent, Dedicated Generator for the NCP, one Motor Driven AFW Pump, and 255 a Battery Charger. $737,229 $3,225,000 0.23 Not cost beneficial $840,441 $3,225,000 0.26 Not cost beneficial Already committed to do, Already committed Install Fire Barriers Around see January, to do, see January, Cables or Reroute the Cables 2009 SAMA 2009 SAMA 256 Away from Fire Sources. $965,083 $19,608 49.22 submittal $1,100,195 $19,608 56.11 submittal Provide an auto start signal for AFW on loss of Standby 276 Feedwater pump. $22,114 $615,605 0.04 Not cost beneficial $25,210 $615,605 0.04 Not cost beneficial Provide a permanent tie-in to 279 the construction air $63,064 $909,893 0.07 Not cost beneficial $71,893 $909,893 0.08 Not cost beneficial 65

Table 2.a.iv RAI Revised SAMA Phase II Analysis Results (Continued)

Revised September, 2011 SAMA RAI Results Revised September, 2011 SAMA RAI Results (External Events Multiplier = 2.0) (External Events Multiplier = 2.28)

Benefit/ Benefit/

SAMA Estimated Estimated Cost Change in Estimated Estimated Cost Change in No. SAMA Title Benefit Cost Ratio Conclusion Benefit Cost Ratio Conclusion compressor.

Add new Unit 2 air compressor similar to the Unit 1 D 280 compressor. $63,064 $814,546 0.08 Not cost beneficial $71,893 $814,546 0.09 Not cost beneficial Provide cross-tie to Unit 1 282 RWST. $18,319 $10,215,000 0.00 Not cost beneficial $20,883 $10,215,000 0.00 Not cost beneficial Improve training to establish feed and bleed cooling given no CCPs are running or a vital Potentially cost Potentially cost 285 instrument board fails $90,528 $26,773 3.38 beneficial $103,202 $26,773 3.85 beneficial Improve training to reduce failure probability to terminate inadvertent safety injections prior to water challenge to Potentially cost Potentially cost 292 PORVs $347,048 $26,773 12.96 beneficial $395,634 $26,773 14.78 beneficial Increase frequency of 295 containment leak rate testing $126,291 $2,500,000 0.05 Not cost beneficial $143,972 $2,500,000 0.06 Not cost beneficial Initiate frequent awareness training for plant operators/

maintenance/ testing staff on key human actions for plant Potentially cost Potentially cost 299 risk $250,281 $26,773 9.35 beneficial $285,320 $26,773 10.66 beneficial Revise procedure FR-H.1 to eliminate or simplify complex (and/or) decision logic for 300(Se establishing feed and bleed Not cost e Note cooling and to improve beneficial; Not cost beneficial; 1)(See operator recovery from initial Requires PWROG Requires PWROG Note 1) mistakes $50,156 $100,000 0.50 approval $57,178 $100,000 0.57 approval 66

Table 2.a.iv RAI Revised SAMA Phase II Analysis Results (Continued)

Revised September, 2011 SAMA RAI Results Revised September, 2011 SAMA RAI Results (External Events Multiplier = 2.0) (External Events Multiplier = 2.28)

Benefit/ Benefit/

SAMA Estimated Estimated Cost Change in Estimated Estimated Cost Change in No. SAMA Title Benefit Cost Ratio Conclusion Benefit Cost Ratio Conclusion Move indication/ operator interface for starting hydrogen 303 igniters to front MCR panel $1,515 $50,000 0.03 Not cost beneficial $1,727 $50,000 0.03 Not cost beneficial Not cost beneficial; HRA analysis Not cost beneficial; considered HRA analysis Add annunciator or alarm procedure E-1 but considered signaling parameters to initiate not SAG-6, procedure E-1 but hydrogen igniters to front panel already not SAG-6, already 304 on MCR $1,515 $50,000 0.03 implemented $1,727 $50,000 0.03 implemented HRA analysis considered HRA analysis Revise procedure E-1 to procedure E-1 but considered include recovery steps for not SAG-6, procedure E-1 but failure to initiate hydrogen Not already Not not SAG-6, already 305 igniters $133,980 Estimated NA implemented $152,737 Estimated NA implemented HRA analysis considered HRA analysis procedures ES- considered 1.3 and FR-Z.1 procedures ES-1.3 Improve operator performance but not SAG-6, and FR-Z.1 but not by enhancing likelihood of Not already Not SAG-6, already 306 recovery from execution errors $149,539 Estimated NA implemented $170,474 Estimated NA implemented Make provisions for connecting 307 ERCW to CCP 2B-B $531 $98,600 0.01 Not cost beneficial $605 $98,600 0.01 Not cost beneficial Note 1 - SAMA 93 was revised (see RAI Response to Question 5.f). SAMA 300 was revised (see RAI Response to Question 5.i).

67

Table 2.a.iv SAMA RAI 3% RDR Sensitivity Results SAMA Revised September 2011 Results SAMA Revised September 2011 Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

SAMA SAMA Title Benefit/ Benefit/ Change in Benefit/ Benefit/ Change in Conclusion No. Cost Ratio Cost Ratio Conclusion Cost Ratio Cost Ratio 7% RDR 3% RDR 7% RDR 3% RDR 4 Improve DC bus Already Already committed to do, see load shedding. committed January,2009 SAMA submittal to do, see January, 2009 SAMA 1.11 1.96 submittal 1.26 2.24 8 Increase training Already Already committed to do, see on response to committed January, 2009 SAMA submittal loss of two 120V to do, see AC buses which January, causes inadvertent 2009 actuation signals. SAMA 0.41 0.74 submittal 0.47 0.85 26 Provide an NO NO additional high pressure injection pump with independent diesel. 0.02 0.03 0.02 0.03 68

Table 2.a.iv SAMA RAI 3% RDR Sensitivity Results SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28) 32 Add the ability to NO NO automatically align emergency core cooling system to recirculation mode upon refueling water storage tank depletion. 0.17 0.29 0.19 0.34 45 Enhance NO NO procedural guidance for use of cross-tied component cooling or service water pumps. 0.14 0.26 0.16 0.30 46 Add a service NO NO water pump. 0.12 0.22 0.14 0.25 56 Install an NO NO independent reactor coolant pump seal injection system, without dedicated diesel. 0.13 0.23 0.15 0.26 70 Install NO NO accumulators for turbine-driven auxiliary feedwater pump flow control valves. 0.35 0.61 0.39 0.70 69

Table 2.a.iv SAMA RAI 3% RDR Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/ Benefit/ Benefit/ Benefit/

SAMA Cost Ratio Cost Ratio Change in Cost Ratio Cost Ratio Change in No. SAMA Title 7% RDR 3% RDR Conclusion 7% RDR 3% RDR Conclusion Install a new condensate storage tank (auxiliary feedwater storage 71 tank). 0.00 0.00 NO 0.00 0.00 NO Replace service and instrument air compressors with more reliable compressors which have self-contained air cooling by shaft 87 driven fans. 0.00 0.00 NO 0.00 0.00 NO Install an unfiltered, hardened 93 containment vent. 0.35 0.61 NO 0.40 0.70 NO Provide a reactor vessel exterior 101 cooling system. 0.07 0.13 NO 0.08 0.14 NO Institute simulator training for severe accident 103 scenarios. 0.15 0.27 NO 0.18 0.31 NO 70

Table 2.a.iv SAMA RAI 3% RDR Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/ Benefit/ Benefit/ Benefit/

SAMA Cost Ratio Cost Ratio Change in Cost Ratio Cost Ratio Change in No. SAMA Title 7% RDR 3% RDR Conclusion 7% RDR 3% RDR Conclusion Install a passive hydrogen control 109 system. 0.07 0.12 NO 0.08 0.14 NO Erect a barrier that would provide enhanced protection of the containment walls (shell) from ejected core debris following a core melt scenario 110 at high pressure. 0.08 0.14 NO 0.09 0.16 NO Add redundant and diverse limit switches to each containment 112 isolation valve. 0.00 0.01 NO 0.00 0.01 NO Install motor generator set trip breakers in 136 control room. 0.05 0.09 NO 0.06 0.10 NO 71

Table 2.a.iv SAMA RAI 3% RDR Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/ Benefit/ Benefit/ Benefit/

SAMA Cost Ratio Cost Ratio Change in Cost Ratio Cost Ratio Change in No. SAMA Title 7% RDR 3% RDR Conclusion 7% RDR 3% RDR Conclusion NO. NO.

Proposed Proposed Eliminate RCP procedure procedure thermal barrier change change dependence on ineffective. ineffective.

CCW, such that See Section See Section loss of CCW does 10 of Oct., 10 of Oct.,

not result directly 2010 SAMA 2010 SAMA 156 in core damage. 21.66 38.10 report 24.70 43.44 report Provide a connection to alternate offsite 176 power source. 0.08 0.13 NO 0.09 0.15 NO Provide self-cooled ECCS 191 seals. 0.00 0.00 NO 0.00 0.00 NO YES; first of YES; first of Provide a means a kind a kind to ensure RCP installation; installation; seal cooling so downside downside that RCP seal impacts on impacts on LOCAs are risk impact risk impact precluded for not not 215 SBO events. 0.77 1.36 assessed 0.88 1.55 assessed Permanent, self-powered pump to backup normal 226 charging pump. 0.43 0.75 NO 0.49 0.86 NO 72

Table 2.a.iv SAMA RAI 3% RDR Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/ Benefit/ Benefit/ Benefit/

SAMA Cost Ratio Cost Ratio Change in Cost Ratio Cost Ratio Change in No. SAMA Title 7% RDR 3% RDR Conclusion 7% RDR 3% RDR Conclusion Permanent, Dedicated Generator for the NCP, one Motor Driven AFW Pump, and a 255 Battery Charger. 0.23 0.40 NO 0.26 0.46 NO Install Fire Already Already Barriers Around committed committed Cables or Reroute to do, see to do, see the Cables Away January, January, from Fire 2009 SAMA 2009 SAMA 256 Sources. 49.22 87.01 submittal 56.11 99.19 submittal Provide an auto start signal for AFW on loss of Standby 276 Feedwater pump. 0.04 0.06 NO 0.04 0.07 NO Provide a permanent tie-in to the construction 279 air compressor. 0.07 .12 NO 0.08 0.14 NO Add new Unit 2 air compressor similar to the Unit 280 1 D compressor. 0.08 0.14 NO 0.09 0.16 NO Provide cross-tie 282 to Unit 1 RWST. 0.00 0.00 NO 0.00 0.00 NO 73

Table 2.a.iv SAMA RAI 3% RDR Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/ Benefit/ Benefit/ Benefit/

SAMA Cost Ratio Cost Ratio Change in Cost Ratio Cost Ratio Change in No. SAMA Title 7% RDR 3% RDR Conclusion 7% RDR 3% RDR Conclusion Improve training to establish feed and bleed cooling No No given no CCPs (Remains (Remains are running or a Potentially Potentially vital instrument cost cost 285 board fails 3.38 6.16 beneficial) 3.85 7.02 beneficial)

Improve training to reduce failure probability to terminate No No inadvertent safety (Remains (Remains injections prior to Potentially Potentially water challenge to cost cost 292 PORVs 12.96 22.69 beneficial) 14.78 25.87 beneficial)

Increase frequency of containment leak 295 rate testing 0.05 0.09 NO 0.06 0.10 NO Initiate frequent awareness training for plant operators/

maintenance/ No No testing staff on (Remains (Remains key human Potentially Potentially actions for plant cost cost 299 risk 9.35 16.51 beneficial) 10.66 18.82 beneficial) 74

Table 2.a.iv SAMA RAI 3% RDR Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/ Benefit/ Benefit/ Benefit/

SAMA Cost Ratio Cost Ratio Change in Cost Ratio Cost Ratio Change in No. SAMA Title 7% RDR 3% RDR Conclusion 7% RDR 3% RDR Conclusion Revise procedure FR-H.1 to eliminate or simplify complex (and/or) decision logic for establishing feed and bleed cooling and to improve YES; YES; operator recovery Requires Requires from initial PWROG PWROG 300 mistake 0.50 0.91 approval 0.57 1.04 approval Move indication/

operator interface for starting hydrogen igniters to front MCR 303 panel 0.03 0.05 NO 0.03 0.06 NO Add annunciator or alarm signaling parameters to initiate hydrogen igniters to front 304 panel on MCR 0.03 0.05 NO 0.03 0.06 NO 75

Table 2.a.iv SAMA RAI 3% RDR Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/ Benefit/ Benefit/ Benefit/

SAMA Cost Ratio Cost Ratio Change in Cost Ratio Cost Ratio Change in No. SAMA Title 7% RDR 3% RDR Conclusion 7% RDR 3% RDR Conclusion Revise procedure E-1 to include recovery steps for failure to initiate Not Not 305 hydrogen igniters Estimated NA NO Estimated NA NO Improve operator performance by enhancing likelihood of recovery from Not Not 306 execution errors Estimated NA NO Estimated NA NO Make provisions for connecting ERCW to CCP 307 2B-B 0.01 0.01 NO 0.01 0.01 NO 76

Table 2.a.iv SAMA RAI 95% CDF Sensitivity Results SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/ Benefit/

Cost Cost Ratio Ratio Mean Benefit/ Mean Benefit/

CDF Cost CDF Cost SAMA (Base Ratio Change in (Base Ratio Change in th No. SAMA Title Case) 95 %CDF Conclusion Case) 95th%CDF Conclusion Already Already committed committed to do, see to do, see January, January, 2009 2009 Improve DC bus load SAMA SAMA 4 shedding. 1.11 2.99 submittal 1.26 3.41 submittal Already Already committed committed Increase training on to do, see to do, see response to loss of two January, January, 120V AC buses which 2009 2009 causes inadvertent SAMA SAMA 8 actuation signals. 0.41 1.10 submittal 0.47 1.26 submittal Provide an additional high pressure injection pump with independent 26 diesel. 0.02 0.04 NO 0.02 0.05 NO 77

Table 2.a.iv SAMA RAI 95% CDF Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Add the ability to automatically align emergency core cooling system to recirculation mode upon refueling water storage tank 32 depletion. 0.17 0.45 NO 0.19 0.52 NO Enhance procedural guidance for use of cross-tied component cooling or service water 45 pumps. 0.14 0.39 NO 0.16 0.44 NO Add a service water 46 pump. 0.12 0.34 NO 0.14 0.38 NO Install an independent reactor coolant pump seal injection system, 56 without dedicated diesel. 0.13 0.35 NO 0.15 0.40 NO Install accumulators for turbine-driven auxiliary feedwater pump flow 70 control valves. 0.35 0.93 NO 0.39 1.06 NO Install a new condensate storage tank (auxiliary 71 feedwater storage tank). 0.00 0.00 NO 0.00 0.00 NO 78

Table 2.a.iv SAMA RAI 95% CDF Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/

Cost Benefit/ Ratio Cost Ratio Benefit/ Mean Benefit/

Mean CDF Cost CDF Cost SAMA (Base Ratio Change in (Base Ratio Change in No. SAMA Title Case) 95th%CDF Conclusion Case) 95th%CDF Conclusion Replace service and instrument air compressors with more reliable compressors which have self-contained air cooling by 87 shaft driven fans. 0.00 0.01 NO 0.00 0.01 NO Install an unfiltered, hardened containment 93 vent. 0.35 0.95 NO 0.40 1.08 NO Provide a reactor vessel 101 exterior cooling system. 0.07 0.20 NO 0.08 0.22 NO Institute simulator training for severe 103 accident scenarios. 0.15 0.41 NO 0.18 0.47 NO Install a passive 109 hydrogen control system. 0.07 0.19 NO 0.08 0.22 NO 79

Table 2.a.iv SAMA RAI 95% CDF Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/

Cost Benefit/ Ratio Cost Ratio Benefit/ Mean Benefit/

Mean CDF Cost CDF Cost SAMA (Base Ratio Change in (Base Ratio Change in No. SAMA Title Case) 95th%CDF Conclusion Case) 95th%CDF Conclusion Erect a barrier that would provide enhanced protection of the containment walls (shell) from ejected core debris following a core melt scenario at high 110 pressure. 0.08 0.21 NO 0.09 0.24 NO Add redundant and diverse limit switches to each containment 112 isolation valve. 0.00 0.01 NO 0.00 0.01 NO Install motor generator set trip breakers in 136 control room. 0.05 0.13 NO 0.06 0.15 NO NO. NO.

Proposed Proposed procedure procedure Eliminate RCP thermal change change barrier dependence on ineffective. ineffective.

CCW, such that loss of See Section See Section CCW does not result 10 of Oct., 10 of Oct.,

156 directly in core damage. 21.66 58.49 2010 SAMA 24.70 66.68 2010 SAMA 80

Table 2.a.iv SAMA RAI 95% CDF Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/

Cost Benefit/ Ratio Cost Ratio Benefit/ Mean Benefit/

Mean CDF Cost CDF Cost SAMA (Base Ratio Change in (Base Ratio Change in No. SAMA Title Case) 95th%CDF Conclusion Case) 95th%CDF Conclusion report report Provide a connection to alternate offsite power 176 source. 0.08 0.20 NO 0.09 0.23 NO Provide self-cooled 191 ECCS seals. 0.00 0.00 NO 0.00 0.00 NO YES; first of YES; first of a kind a kind installation; installation; Provide a means to downside downside ensure RCP seal cooling impacts on impacts on so that RCP seal LOCAs risk impact risk impact are precluded for SBO not not 215 events. 0.77 2.08 assessed 0.88 2.37 assessed Permanent, self- Yes Yes powered pump to backup Potentially Potentially 226 normal charging pump. 0.43 1.15 cost beneficial 0.49 1.32 cost beneficial 81

Table 2.a.iv SAMA RAI 95% CDF Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/

Cost Benefit/ Ratio Cost Ratio Benefit/ Mean Benefit/

Mean CDF Cost CDF Cost SAMA (Base Ratio Change in (Base Ratio Change in No. SAMA Title Case) 95th%CDF Conclusion Case) 95th%CDF Conclusion Permanent, Dedicated Generator for the NCP, one Motor Driven AFW Pump, and a Battery 255 Charger. 0.23 0.62 NO 0.26 0.70 NO Already Already committed to committed to Install Fire Barriers do, see do, see Around Cables or January, January, Reroute the Cables 2009 SAMA 2009 SAMA 256 Away from Fire Sources. 49.22 132.89 submittal 56.11 151.50 submittal Provide an auto start signal for AFW on loss of Standby Feedwater 276 pump. 0.04 0.10 NO 0.04 0.11 NO Provide a permanent tie-in to the construction air 279 compressor. 0.07 0.19 NO 0.08 0.21 NO Add new Unit 2 air compressor similar to the 280 Unit 1 D compressor. 0.08 0.21 NO 0.09 0.24 NO Provide cross-tie to Unit 282 1 RWST. 0.00 0.00 NO 0.00 0.01 NO 82

Table 2.a.iv SAMA RAI 95% CDF Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/

Cost Benefit/ Ratio Cost Ratio Benefit/ Mean Benefit/

Mean CDF Cost CDF Cost SAMA (Base Ratio Change in (Base Ratio Change in No. SAMA Title Case) 95th%CDF Conclusion Case) 95th%CDF Conclusion Improve training to No No establish feed and bleed (Remains (Remains cooling given no CCPs Potentially Potentially are running or a vital cost cost 285 instrument board fails 3.38 9.13 beneficial) 3.85 10.41 beneficial)

Improve training to reduce failure probability No No to terminate inadvertent (Remains (Remains safety injections prior to Potentially Potentially water challenge to cost cost 292 PORVs 12.96 35.00 beneficial) 14.78 39.90 beneficial)

Increase frequency of containment leak rate 295 testing 0.05 0.14 NO 0.06 0.16 NO Initiate frequent awareness training for No No plant operators/ (Remains (Remains maintenance/ testing Potentially Potentially staff on key human cost cost 299 actions for plant risk 9.35 25.24 beneficial) 10.66 28.77 beneficial) 83

Table 2.a.iv SAMA RAI 95% CDF Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/

Cost Benefit/ Ratio Cost Ratio Benefit/ Mean Benefit/

Mean CDF Cost CDF Cost SAMA (Base Ratio Change in (Base Ratio Change in No. SAMA Title Case) 95th%CDF Conclusion Case) 95th%CDF Conclusion Revise procedure FR-H.1 to eliminate or simplify complex (and/or) decision logic for establishing feed and bleed cooling and to YES; YES; improve operator Requires Requires recovery from initial PWROG PWROG 300 mistakes 0.50 1.35 approval 0.57 1.54 approval Move indication/ operator interface for starting hydrogen igniters to front 303 MCR panel 0.03 0.08 NO 0.03 0.09 NO Add annunciator or alarm signaling parameters to initiate hydrogen igniters 304 to front panel on MCR 0.03 0.08 NO 0.03 0.09 NO Revise procedure E-1 to include recovery steps Not for failure to initiate Not Estimat 305 hydrogen igniters Estimated NA NO ed NA NO 84

Table 2.a.iv SAMA RAI 95% CDF Sensitivity Results (Continued)

SAMA Revised September 2011 SAMA Revised September 2011 Results Results (External Events (External Events Multiplier = 2.0) Multiplier = 2.28)

Benefit/

Cost Benefit/ Ratio Cost Ratio Benefit/ Mean Benefit/

Mean CDF Cost CDF Cost SAMA (Base Ratio Change in (Base Ratio Change in No. SAMA Title Case) 95th%CDF Conclusion Case) 95th%CDF Conclusion Improve operator performance by enhancing likelihood of Not recovery from execution Not Estimat 306 errors Estimated NA NO ed NA NO Make provisions for connecting ERCW to 307 CCP 2B-B 0.01 0.01 NO 0.01 0.02 NO 85

Table 2.a.iv RAI Revised Evacuation Speed Sensitivity Results Base Case Faster Evacuation Slower Evacuation (2.2m/s) (3.4m/s) (1.6m/s)

Total Total Total Person- Economic Person- Economic Person-Case Rem Cost ($) Rem Cost ($) Rem Economic Cost ($)

I. Early 2.96E+06 6.34E+09 2.83E+06 6.34E+09 3.19E+06 6.34E+09 II. Bypass 2.39E+06 5.31E+09 2.35E+06 5.31E+09 2.46E+06 5.31E+09 III. Late 1.09E+06 3.19E+09 1.09E+06 3.19E+09 1.09E+06 3.19E+09 IV. SERF 3.22E+05 5.85E+08 3.16E+05 5.85E+08 3.34E+05 5.85E+08 86

Table 4.d-2 RAI SAMAs Identified for 18 Key Fire Scenarios from the FIVE Screening Analysis SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition Reduces frequency of fire scenarios in Install automatic fire this room with or suppression in AB without manual Maximum reduction in CDF 757-A13 (refueling suppression FIVE is 7.46E-7 corresponding to Excessive Implementation 308 room) success contributors about $84,000 benefit. Cost Reduces frequency of fire scenarios in Install automatic fire this room with or suppression in AB without manual Maximum reduction in CDF 757-A22 ( 125v vital suppression FIVE is 8.35E-7 corresponding to Excessive Implementation 309 battery board room) success contributors about $94,000 benefit. Cost Reduces frequency of fire scenarios in Install automatic fire this room with or suppression in AB without manual Maximum reduction in CDF 786-AR (auxiliary suppression FIVE is 3.1E-7 corresponding to Excessive Implementation 310 building roof) success contributors about $35,000 benefit. Cost Reduces frequency Install automatic fire of fire scenarios in suppression for the this room with or main panels of the without manual Maximum reduction in CDF main control room suppression FIVE is 9.65E-7 corresponding to Excessive Implementation 311 CB 755-C12 success contributors about $108,000 benefit. Cost 87

Table 4.d-2 RAI SAMAs Identified for 18 Key Fire Scenarios from the FIVE Screening Analysis (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition Reduces frequency Install automatic fire of fire scenarios in suppression in areas this room with or of small ignition without manual Maximum reduction in CDF sources in the suppression FIVE is 2.20E-7 corresponding to Excessive Implementation 312 turbine building success contributors about $25,000 benefit. Cost Enhance fire department training and carry out drills Maximum reduction in CDF for the 9 key rooms Reduces frequency is the sum of all sequence 4 contributing the most of fire scenarios contributions or 4.59E-6 to the sum of the with or without corresponding to about FIVE CDF screening manual suppression FIVE $516,000 benefit. See note 313 frequencies. success contributors (1) Already Implemented Per Table 15f, SAMAs previously identified are:

70, 73, 79, 282, 285, 299, and 300. SAMAs 285 and Enhance training for 299 previously committed local control of AFW Reduce probability to. Maximum reduction in given station of losing all CDF is the sum of all blackout, loss of secondary heat sequence 4 contributions or control air, or fires removal during FIVE 3.89E-6 corresponding to 314 affecting AFW LCVs. station blackout. contributors about $437,000 benefit. Already Implemented 88

Table 4.d-2 RAI SAMAs Identified for 18 Key Fire Scenarios from the FIVE Screening Analysis (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition Per Table 15e, applicable SAMAs previously identified are: 50, 58, 61, 155, 242, and 260. SAMAs 61 and 155 are already Reduce probability implemented. Maximum of significant RCP reduction in CDF is the sum Upgrade seals or seal leakage in of all sequence 4 enhance procedures event of losing all contributions or 2.28E-6 to cooldown RCS seal cooling and FIVE corresponding to about 315 before leakage seal injection. contributors $256,000 benefit. Already Implemented 8kv power cables are expensive and difficult to locate. Maximum reduction Reroute offsite in CDF is the sum of all power cables away Reduce demands sequence 4 contributions or from fire area 737- on onsite AC power FIVE 4.24e-7 corresponding to Excessive Implementation 316 A1A system contributors about $48,000 benefit. Cost 8kv power cables are expensive and difficult to locate. Maximum reduction Reroute offsite in CDF is the sum of all power cables away Reduce demands sequence 4 contributions or from fire area 737- on onsite AC power FIVE 5.05e-7 corresponding to Excessive Implementation 317 A1B system contributors about $57,000 benefit. Cost 89

Table 4.d-2 RAI SAMAs Identified for 18 Key Fire Scenarios from the FIVE Screening Analysis (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition 8kv power cables are expensive and difficult to locate. Maximum reduction Reroute offsite in CDF is the sum of all power cables away Reduce demands sequence 4 contributions or from fire area 737- on onsite AC power FIVE 2.89e-7 corresponding to Excessive Implementation 318 A1C system contributors about $33,000 benefit. Cost 2PL6510A & 2PL6512A are the only 6-9kv SDBD 2A-A cables in 737-A1B and they are to be protected with fire wrap for Appendix R.

Reroute onsite Maximum reduction in CDF power cables to Limit fire impact to is the sum of all sequence 4 either SD BD 2A-A just one train of SD contributions or 5.05e-7 or 2B-B away from BDs when also fail FIVE corresponding to about TVA implementation in 319 fire area 737-A1B offsite power. contributors $57,000 benefit. process Providing nitrogen bottles as Per Table 15f, SAMAs accumulators for previously identified are:

selected valves Reduce joint human 70, 73, 79, 282, 285, 299, would reduce action error probability and 300. SAMAs 285 and difficulty. Enhance between recovery of 299 previously committed procedures already AFW given loss of to. Maximum reduction in implemented, control air (HAFR1) CDF is the sum of all additional training and action to initiate sequence 4 contributions or could reduce error feed and bleed FIVE 8.75e-7 corresponding to 320 rate cooling (HAOB2) contributors about $98,000 benefit. Already Implemented 90

Table 4.d-2 RAI SAMAs Identified for 18 Key Fire Scenarios from the FIVE Screening Analysis (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition Reroute cables in fire area Aux Bldg 757-A22 to preclude failure of both trains of SD BDs (6.9kv SD BD 2B-B and Limit fire impact to Maximum reduction in CDF 480v SD BDs on A just one train of SD FIVE is 8.35E-7 corresponding to Excessive Implementation 321 train) BDs contributors about $94,000 benefit. Cost 8kv power cables are Reroute offsite expensive and difficult to power cables away locate. Maximum reduction from Aux Bldg 786- Reduce demands in CDF is 3.1E-7 AR - auxiliary on onsite AC power FIVE corresponding to about Excessive Implementation 322 building roof system contributors $35,000 benefit. Cost Enhance procedures for control room fire Plant abnormal operating evacuation and instructions exits for fires in associated each room. AOI-30.2C.69 procedures to applies to these rooms.

achieve safe Limit potential for Maximum reduction in CDF shutdown from operator error FIVE is 1.23E-6 corresponding to 323 shutdown panel following evacuation contributors about $138,000 benefit. Already Implemented 8kv power cables are expensive and difficult to locate. Maximum reduction Reroute offsite Reduce demands in CDF is 5.92E-7 power cables away on onsite AC power FIVE corresponding to about Excessive Implementation 324 from turbine building system contributors $67,000 benefit. Cost 91

Table 4.d-2 RAI SAMAs Identified for 18 Key Fire Scenarios from the FIVE Screening Analysis (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition

• Provide an additional diesel Per Table 15e, previously generator - 2 MW identified SAMAs are: 9, 10, blackout diesel 11, 12, 229, and 244. WBN generators to power is purchasing a 2MW charging pumps, blackout diesel generator igniters, Inverters, for Unit 2. SAMAs 10, 11, etc. SAMA 9 and 12 are already implemented. Procedures

• Revise procedure for cross-tying 6.9 kV buses to allow bypass of are available but DG trips. SAMA 10 Improved reliability conservatively not credited

• Improve 6.9 kV bus of onsite AC power in the FIVE analyses. It is crosstie capability. sources. credited in the SAMA model SAMA 11,229,244 Procedures already for internal events.

• Cross-tie diesel modified to add Maximum reduction in CDF generators within or manual cross-tie FIVE is 3.82E-7 corresponding to 325 to the other units. capabilities contributors about $43,000 benefit. Already Implemented 92

Table 4.d-2 RAI SAMAs Identified for 18 Key Fire Scenarios from the FIVE Screening Analysis (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition

• Modify procedure to provide ability to align diesel power to more air compressors.

SAMA 86

• Improve reliability of ACAS compressors when AC power is available. SAMA 188

• Provide a permanent tie-in to the construction air compressor. SAMA 279

• Add a new Unit 2 air compressor Per Table 15e, SAMAs similar to Unit 1 D previously identified include compressor. SAMA 86, 188, 279, 280, and 281.

280 SAMAs 86, 188, 279 and Already Implemented. A

• Replace the ACAS 280 are not cost effective. study has been initiated to dryers and Maximum reduction in CDF see if it is practical to compressors. Improve availability FIVE is 7.22E-7 corresponding to improve ACAS availability 326 SAMA 281 of air system contributors about $81,000 benefit. (SAMA 281).

93

Table 4.d-2 RAI SAMAs Identified for 18 Key Fire Scenarios from the FIVE Screening Analysis (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition Per Table 15a, SAMAs previously identified are:

46, 53, 56, 62, 155, 158, and 271. SAMAs 46 and 53 are not cost effective.

SAMAs 62,155, 158 and 278 are already implemented. Action HAERCW2 has been added to the SAMA model to allow for crosstie of the fire protection water to a failed ERCW system. The action can be accomplished within the 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> available for most seal leakage rates.

For 480 gpm leak rates no credit is taken for the crosstie. The analysis to Improve reliability of Pump extend the time to CCS ERCW system improvements failure and to implement failure in response to already and refine the analysis is plant trip or limit the implemented. not cost effective.

potential for seal SAMAs identified to Maximum reduction in CDF leak given loss of all limit dependence on FIVE is 6.39E-8 corresponding to 327 RCP seal cooling. ERCW contributors about $7,000 benefit. Already Implemented Note (1) 94

The fire department at Watts Bar is a dedicated organization that responds to fires on site and maintains the majority of the fire protection equipment. The fire response organization is staffed and equipped for firefighting activities. The fire brigade is comprised of a fire brigade leader and four fire brigade members (minimum). The fire brigade shall not include the Shift Manager or the other members of the minimum shift crew necessary for safe shutdown of the unit, nor any personnel required for other essential functions during a fire emergency. Additional support is available when needed through an agreement with a local fire department (s). The fire brigade composition may be less than the minimum requirements for a period of time not to exceed two hours, in order to accommodate unexpected absence, provided immediate action is taken to fill the required positions.

The fire department already schedules quarterly fire drills for each rotating shift crew in specific fire areas. Each drill includes a formal critique to evaluate the effectiveness of the fire brigade in responding to a simulated fire emergency. The drills conducted have already included 8 of the 9 areas with relatively high screening values in the final FIVE screening analysis. The one area for which no drills have been conducted is AB 786 RA, which has minimal combustibles; i.e., less than 5 minute fire. Both announced and unannounced drills are conduced to fulfill NRC, OSHA, and NEIL training requirements. Abnormal operating instruction series AOI-30.2 is to direct the actions to be carried out for all Appendix R cooldowns. The steps required are listed as a function of the room in which the fire occurs. Further, fire pre-plans are developed for each fire area to facilitate fire fighting. These pre-plans contain the following types of information laid out on an easy to read room diagram; primary and secondary access routes, stairs and fire related barriers, safe shutdown equipment locations, hose stations, installed fire suppression systems, and locked access locations.

95

Table 5.c-1. October 2010, SAMA Model Release Categories, Frequencies, Doses, and Economic Costs Release Category 1 - LERF Release Category 2 - BYPASS Release Category 3 - LATE Release Category 5 - SERF Dose Dose Dose Dose Risk Economi Risk Economi Risk Economi Risk Economi SAM Freq (man - c Risk Freq (man - c Risk Freq (man - c Risk Freq (man - c Risk A (per yr) rem/yr) ($/yr) (per yr) rem/yr) ($/yr) (per yr) rem/yr) ($/yr) (per yr) rem/yr) ($/yr) 1.26E- 3.72E+0 3.50E- 8.37E- 1.30E- 1.42E+0 3.84E- 1.23E+0 Base 06 0 $7,971 07 01 $1,859 05 1 $41,614 06 0 $2,243 1.25E- 3.70E+0 3.45E- 8.25E- 1.29E- 1.40E+0 3.81E- 1.23E+0 4 06 0 $7,929 07 01 $1,832 05 1 $41,231 06 0 $2,231 1.25E- 3.71E+0 3.50E- 8.37E- 1.30E- 1.42E+0 3.82E- 1.23E+0 8 06 0 $7,963 07 01 $1,859 05 1 $41,608 06 0 $2,235 1.23E- 3.65E+0 3.50E- 8.37E- 1.28E- 1.40E+0 3.81E- 1.23E+0 26 06 0 $7,827 07 01 $1,859 05 1 $40,944 06 0 $2,228 6.51E- 1.93E+0 3.50E- 8.37E- 1.30E- 1.41E+0 2.36E- 7.60E-32 07 0 $4,134 07 01 $1,859 05 1 $41,506 06 01 $1,380 1.26E- 3.72E+0 3.50E- 8.37E- 1.30E- 1.42E+0 3.83E- 1.23E+0 45 06 0 $7,970 07 01 $1,859 05 1 $41,586 06 0 $2,241 1.25E- 3.70E+0 3.49E- 8.35E- 8.11E- 1.36E+0 3.77E- 1.21E+0 46 06 0 $7,924 07 01 $1,855 06 1 $39,797 06 0 $2,203 1.18E- 3.48E+0 3.50E- 8.37E- 1.27E- 8.82E+0 3.21E- 1.03E+0 56 06 0 $7,459 07 01 $1,859 05 0 $25,891 06 0 $1,880 1.25E- 3.70E+0 3.48E- 8.33E- 1.30E- 1.38E+0 3.79E- 1.22E+0 70 06 0 $7,936 07 01 $1,850 05 1 $40,449 06 0 $2,214 1.26E- 3.72E+0 3.50E- 8.37E- 1.30E- 1.42E+0 3.84E- 1.23E+0 71 06 0 $7,971 07 01 $1,859 05 1 $41,614 06 0 $2,243 1.26E- 3.72E+0 3.50E- 8.37E- 1.30E- 1.42E+0 3.83E- 1.23E+0 87 06 0 $7,971 07 01 $1,859 05 1 $41,592 06 0 $2,242 1.26E- 3.72E+0 3.50E- 8.37E- 1.30E- 1.42E+0 3.84E- 1.23E+0 93 06 0 $7,971 07 01 $1,859 05 1 $41,614 06 0 $2,243 6.14E- 1.82E+0 3.50E- 8.37E- 1.32E- 1.44E+0 3.84E- 1.23E+0 101 07 0 $3,896 07 01 $1,859 05 1 $42,256 06 0 $2,243 96

Table 5.c-1. October 2010, SAMA Model Release Categories, Frequencies, Doses, and Economic Costs (Continued)

Release Category 1 - LERF Release Category 2 - BYPASS Release Category 3 - LATE Release Category 5 - SERF Dose Dose Dose Econo Risk Econom Dose Economi Risk Economi Risk mic SAM Freq (man - ic Risk Freq Risk (man c Risk Freq (man - c Risk Freq (man - Risk A (per yr) rem/yr) ($/yr) (per yr) - rem/yr) ($/yr) (per yr) rem/yr) ($/yr) (per yr) rem/yr) ($/yr) 10 5.20E- 3.42E- 9.85E- 1.49E-3 07 1.54E+00 $3,299 07 8.17E-01 $1,816 06 1.07E+01 $31,464 06 4.79E-01 $871 10 6.43E- 3.50E- 1.26E- 3.84E-9 07 1.90E+00 $4,078 07 8.37E-01 $1,859 05 1.37E+01 $40,212 06 1.23E+00 $2,243 11 9.51E- 3.50E- 1.31E- 3.84E-0 07 2.82E+00 $6,037 07 8.37E-01 $1,859 05 1.43E+01 $41,825 06 1.23E+00 $2,243 11 1.26E- 3.42E- 1.30E- 3.84E-2 06 3.72E+00 $7,971 07 8.18E-01 $1,816 05 1.42E+01 $41,614 06 1.23E+00 $2,243 13 1.25E- 3.50E- 1.30E- 3.82E-6 06 3.71E+00 $7,954 07 8.37E-01 $1,859 05 1.42E+01 $41,611 06 1.23E+00 $2,234 15 1.19E- 3.50E- 9.70E- 3.44E-6 06 3.53E+00 $7,568 07 8.37E-01 $1,859 06 1.06E+01 $30,988 06 1.11E+00 $2,011 17 1.14E- 2.72E- 1.05E- 3.46E-6 06 3.37E+00 $7,227 07 6.50E-01 $1,445 05 1.14E+01 $33,523 06 1.11E+00 $2,025 97

Table 5.c-1. October 2010, SAMA Model Release Categories, Frequencies, Doses, and Economic Costs (Continued)

Release Category 1 - LERF Release Category 2 - BYPASS Release Category 3 - LATE Release Category 5 - SERF Dose Dose Dose Dose Risk Economi Risk Economi Risk Economi Risk Economi SAM Freq (man - c Risk Freq (man - c Risk Freq (man - c Risk Freq (man - c Risk A (per yr) rem/yr) ($/yr) (per yr) rem/yr) ($/yr) (per yr) rem/yr) ($/yr) (per yr) rem/yr) ($/yr) 1.26E- 3.72E+0 3.50E- 8.37E- 1.30E- 1.42E+0 3.84E- 1.23E+0 191 06 0 $7,971 07 01 $1,859 05 1 $41,614 06 0 $2,243 1.16E- 3.44E+0 3.50E- 8.37E- 7.78E- 8.47E+0 3.18E- 1.02E+0 215 06 0 $7,369 07 01 $1,859 06 0 $24,856 06 0 $1,860 1.16E- 3.44E+0 3.50E- 8.37E- 7.78E- 8.47E+0 3.18E- 1.02E+0 226 06 0 $7,369 07 01 $1,859 06 0 $24,856 06 0 $1,860 1.05E- 3.10E+0 1.88E- 4.50E- 1.05E- 1.14E+0 3.47E- 1.12E+0 255 06 0 $6,651 07 01 $1,001 05 1 $33,373 06 0 $2,026 9.42E- 2.79E+0 2.63E- 6.28E- 9.77E- 1.06E+0 2.88E- 9.26E-256 07 0 $5,978 07 01 $1,396 06 1 $31,211 06 01 $1,682 1.25E- 3.70E+0 3.48E- 8.32E- 1.30E- 1.41E+0 3.81E- 1.23E+0 276 06 0 $7,926 07 01 $1,849 05 1 $41,368 06 0 $2,231 1.25E- 3.71E+0 3.50E- 8.35E- 1.28E- 1.39E+0 3.80E- 1.22E+0 279 06 0 $7,954 07 01 $1,856 05 1 $40,768 06 0 $2,223 1.25E- 3.71E+0 3.50E- 8.35E- 1.28E- 1.39E+0 3.80E- 1.22E+0 280 06 0 $7,954 07 01 $1,856 05 1 $40,768 06 0 $2,223 1.25E- 3.71E+0 3.42E- 8.18E- 1.30E- 1.42E+0 3.83E- 1.23E+0 282 06 0 $7,965 07 01 $1,816 05 1 $41,614 06 0 $2,238 1.25E- 3.70E+0 3.49E- 8.34E- 1.30E- 1.42E+0 3.74E- 1.20E+0 285 06 0 $7,936 07 01 $1,852 05 1 $41,605 06 0 $2,186 5.97E- 1.77E+0 3.50E- 8.37E- 1.29E- 1.41E+0 2.03E- 6.54E-292 07 0 $3,788 07 01 $1,859 05 1 $41,266 06 01 $1,189 1.26E- 3.72E+0 3.50E- 8.37E- 1.30E- 1.42E+0 3.89E- 1.25E-295 06 0 $7,971 07 01 $1,859 05 1 $41,614 09 03 $2 1.23E- 3.64E+0 3.50E- 8.37E- 1.19E- 1.30E+0 3.71E- 1.19E+0 299 06 0 $7,803 07 01 $1,859 05 1 $38,156 06 0 $2,169 1.25E- 3.70E+0 3.49E- 8.34E- 1.30E- 1.42E+0 3.78E- 1.22E+0 300 06 0 $7,936 07 01 $1,852 05 1 $41,604 06 0 $2,209 303 1.25E- 3.71E+0 $7,964 3.50E- 8.37E- $1,859 1.30E- 1.42E+0 $41,589 3.84E- 1.23E+0 $2,243 98

Table 5.c-1. October 2010, SAMA Model Release Categories, Frequencies, Doses, and Economic Costs (Continued)

Release Category 1 - LERF Release Category 2 - BYPASS Release Category 3 - LATE Release Category 5 - SERF Dose Dose Dose Dose Risk Economi Risk Economi Risk Economi Risk Economi SAM Freq (man - c Risk Freq (man - c Risk Freq (man - c Risk Freq (man - c Risk A (per yr) rem/yr) ($/yr) (per yr) rem/yr) ($/yr) (per yr) rem/yr) ($/yr) (per yr) rem/yr) ($/yr) 06 0 07 01 05 1 06 0 1.25E- 3.71E+0 3.50E- 8.37E- 1.30E- 1.42E+0 3.84E- 1.23E+0 304 06 0 $7,964 07 01 $1,859 05 1 $41,589 06 0 $2,243 9.06E- 2.68E+0 3.50E- 8.37E- 1.29E- 1.40E+0 3.84E- 1.23E+0 305 07 0 $5,749 07 01 $1,859 05 1 $41,199 06 0 $2,243 9.07E- 2.68E+0 3.50E- 8.37E- 1.30E- 1.42E+0 3.79E- 1.22E+0 306 07 0 $5,755 07 01 $1,859 05 1 $41,563 06 0 $2,218 1.26E- 3.72E+0 3.50E- 8.37E- 1.30E- 1.42E+0 3.84E- 1.23E+0 307 06 0 $7,969 07 01 $1,859 05 1 $41,605 06 0 $2,243 99

RAI Response Submittal of May 13, 2011 TVAs responses to items 1 through 16 have been reviewed and concluded to be unchanged by correcting the total person-rem computed for each release category. With regard to item 12 (RAI 5.e), the previous response recognized that SAMA 70 would exceed a cost-benefit ratio of 1.0 if an uncertainty multiplier of 2.78 were assumed. This exceedance is now slightly greater because of the change correcting the total person-rem computed for each release category. This SAMA 70 has, however, been superseded by TVAs commitment to implement SAMA 339.

The list of commitments in enclosure 2 is also unchanged.

0

RAI Response Submittal of May 25, 2011 TVAs responses to items 2 through 3 have been reviewed and concluded to be unchanged by correcting the total person-rem computed for each release category.

The TVA response to item 5 has been reviewed and some discussion is offered to the response for part b. Correcting the total person-rem computed for each release category required a change to the maximum averted cost risk (MACR). The changes offered caused the SAMA 93 cost benefit ratio to go from just below 1.0 to slightly greater than 1.0 for the CDF 95th percentile sensitivity case. However, the potential benefits of implementing SAMA 93 are also addressed by SAMA 58. Hence, the existing commitment in enclosure 2 to the May 25, 2011 submittal adequately addresses this potentially cost beneficial SAMA.

Furthermore, the next highest benefit-cost ratio SAMA in the revised Table 2.a.iv-10, is SAMA 255 with a 95th percentile ratio of 0.70. If the 2.78 95th percentile multiplier is used instead of the 2.7, then SAMA 255 would have a benefit-cost ratio of 0.72.

Therefore, all remaining SAMAs are well below the 1.0 benefit-cost ratio using the 2.78 95th percentile multiplier and no other SAMA conclusions would change.

Part f of item 5 gives a breakdown of contributions to the MACR. This table is updated and presented below as Table 2.a.iv.f.

The response to item 15 (RAI 6) also involves changes to Tables 15-1 and 15-2. The updated tables are presented below. Table 15-3 summarizes a Phase 1 rescreening of the SAMAs which were screened because of Excessive Cost of Very Low Benefit. Table 15-3 has been reviewed in light of correcting the total person-rem computed for each release category and the conclusions found to be unchanged.

The list of commitments in enclosure 2 is also unchanged.

1

Table 2.a.iv-f from May 25, 2011 Submittal Revised September, 2011 October 2010, (RAI) SAMA Cost Category SAMA Report Results Off-Site Exposure Cost $ $514,379 $535,803 Off-Site Economic Cost $ $466,032 $720,324 On-Site Exposure Cost $ $8,153 $8,153 On-Site Economic Cost $ $666,023 $666,023 Total Base Cost $ $1,654,587 $1,930,303 Base Cost with External Event Multiplier 2.0 $3,309,174 $3,860,606 Base Cost with External Event Multiplier 2.28 $3,772,461 $4,401,090 Table 15 Revised RAI SAMA Maximum Averted Cost of Risk (MACR) Results Cost Description Revised September, 2011 (RAI) SAMA Results MACR Onsite MACR Offsite Costs Costs (Function of (Function of Core Core Damage Damage and Release Total without Release Costs)

MACR Costs)

Base Cost with External $ 3,860,606 $1,347,351 34.9% $2,513,254 65.1%

Event Multiplier 2.0 Base Cost with External $4,401,090 $1,535,981 34.9% $2,865,110 65.1%

Event Multiplier 2.28 95% Cost with External $10,423,635 $3,637,849 34.9% $6,785,786 65.1%

Multiplier 2.0 (95%

Multiplier 2.70) 95% Cost with External $11,882,944 $4,147,147 34.9% $7,735,796 65.1%

Multiplier 2.28 (95%

Multiplier 2.70) 2

Table 15-2. 95% MACR Risk Reduction Case Types LERF (Early  % Potential SAMA & Contribution Change in Case CDF Bypass) LATE SERF to MACR MACR 1 Changed Linear Linear Linear 100.0% $11,882,944 2 Fixed Changed Fixed Fixed 13.2% $1,564,242 3 Fixed Fixed Changed Fixed 48.6% $5,779,353 4 Fixed Fixed Fixed Changed 3.3% $389,118 5 Changed Changed Fixed Fixed 16.4% $1,952,178 6 Changed Fixed Changed Fixed 75.1% $8,927,170 7 Changed Fixed Fixed Changed 11.1% $1,315,493 3

Table 15-3. Phase I SAMA Candidates SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition 2 Replace lead-acid Extended DC power NEI 05- Basis for Screening: For a plant with Excessive batteries with fuel availability during an SBO. 01 (Rev significant construction already completed, Implementation cells. A) the cost of implementation caused by Cost. (Table replacing all batteries with fuel cells, 15-2 Case 1) including structural, electrical, and HVAC changes required, including a fuel supply which does not currently exist on site, would exceed $2M and the bounding benefit would be less than 13% reduction in CDF. More complex technology with alternate fuel source requirements.

Combine with SAMA 174.

9 Provide an Increased availability of NEI 05- Basis for Screening: For a plant with Excessive additional diesel on-site emergency AC 01 (Rev significant construction already completed, Implementation generator. power. A) the cost of implementation ($8,500,000 to Cost. (Table

$22,800,000, representative of similar 15-2 Case 1) nuclear power plants, WBN specific cost estimate $5,000,000) and benefit would be less than 28% reduction in CDF. WBN in process of updating cost estimate for non-SAMA reasons but expected to not be SAMA cost beneficial. Combine with SAMA 233.

4

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition 13 Install an Reduced probability of loss NEI 05-01 Basis for Screening: There are two existing Excessive additional, buried of off-site power. (Rev A) 161 kV connections to a nearby dam Implementation off-site power switchyard above ground. The estimated Cost. (Table source. cost of burying them would exceed $5M 15-2 Case 1) and the benefit would be much less than 28% reduction in CDF. Pricing of above ground 161 kV line from hydro to construction yard was excessive. Buried would be even more.

14 Install a gas turbine Increased availability of NEI 05-01 Basis for Screening: For a plant with Excessive generator. on-site AC power. (Rev A) significant construction already completed, Implementation the estimated cost of implementation Cost. (Table

($3,350,000 to $30,000,000, representative 15-2 Case 1) of similar nuclear power plants) would be much less than 28% reduction in CDF.

Based on cost of completion of 5th Diesel Generator, addition of turbine/gen with extra fuel source and building would be even more expensive.

15 Install tornado Increased availability of NEI 05-01 Basis for Screening: A gas turbine Excessive protection on gas on-site AC power. (Rev A) generator is not available at the Watts Bar Implementation turbine generator. site. Based on cost of completion of 5th Cost. (Table Diesel Generator, addition of turbine/gen 15-2 Case 1) with extra fuel source and building would be even more expensive.

24 Bury off-site power Improved off-site power NEI 05-01 Basis for Screening: The distance that Excessive lines. reliability during severe (Rev A) would be necessary to bury offsite power Implementation weather. lines would be significant since severe Cost. (Table weather to which transmission lines are 15-2 Case 1) susceptible typically affects a broad area.

5

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition For a plant with significant construction already completed, the estimated cost of implementation would exceed the potential benefit. Similar to #13 except two lines buried. Approx 2 miles underground duct bank and 161 underground cable. Benefit would be much less than 40% of CDF.

25 Install an Improved prevention of NEI 05-01 Basis for Screening: The previous passive Excessive independent active core melt sequences. (Rev A) UHI system was removed from the WBN Implementation or passive high design. For a plant with significant Cost. (Table pressure injection construction already completed, the 15-2 Case 1) system. estimated cost of implementation would exceed the bounding benefit. Design basis safety reanalysis would be around $3M.

Engineering, construction, hardware, and testing costs would be in addition to that.

Total costs would greatly exceed $3M and bounding risk reduction benefit would be less than 25% reduction in CDF.

34 Provide an in- Continuous source of water NEI 05-01 Basis for Screening: For a plant with Not Feasible to containment to the safety injection (Rev A) significant construction already completed, implement reactor water pumps during a LOCA the estimated cost of implementation inside storage tank. event, since water released would exceed the bounding benefit. There containment from a breach of the is limited room in containment to install an due to limited primary system collects in in-containment RWST. Complex space available.

the in-containment reactor engineering problem. Ice condenser Will also screen water storage tank, and currently acts as in-containment water on Excessive thereby eliminates the need source approx equal to the RWST after Cost. (Table to realign the safety melt. Additional tank would reduce 15-2 Case 1) injection pumps for long- containment available volume for pressure 6

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition term post-LOCA suppression and raise post accident water recirculation. level with additional post accident water level flooding issues.

37 Upgrade the For a plant like the NEI 05-01 Basis for Screening: For a plant with Excessive chemical and Westinghouse AP600, (Rev A) significant construction already completed, Implementation volume control where the chemical and the estimated cost of implementation to Cost. (Table system to mitigate volume control system increase CVCS flow capacity would 15-2 Case 1) small LOCAs. cannot mitigate a small exceed the bounding benefit. WBN LOCA, an upgrade would currently has 2 trains of high head decrease the frequency of charging pumps. Additional charging core damage. pump would require additional power source and water supply. Recirculation from the sump would still be required.

Cost would exceed $2M and benefit would be much less than 10% reduction in CDF.

39 Replace two of the Reduced common cause NEI 05-01 Basis for Screening: For a plant with Excessive four electric safety failure of the safety (Rev A) significant construction already completed, Implementation injection pumps injection system. This the estimated cost of implementation to Cost. (Table with diesel- SAMA was originally replace the SI pumps would exceed the 15-2 Case 1) powered pumps. intended for the bounding benefit. Current SI pumps are Westinghouse-CE System Diesel backed. Diesel driven pumps 80+, which has four trains would require a separate building along of safety injection. with appropriate protection (tornado, However, the intent of this seismic, etc., and ASME piping into SAMA is to provide containment).

diversity within the high-and low-pressure safety injection systems.

41 Create a reactor Allows low pressure NEI 05-01 Basis for Screening: For a plant with Excessive coolant emergency core cooling (Rev A) significant construction already completed, Implementation 7

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition depressurization system injection in the the estimated cost of implementation to Cost. (Table system. event of small LOCA and install larger PORVs would exceed the 15-2 Case 1) high-pressure safety bounding benefit. Would require ASME injection failure. connections to the RCS and appropriately qualified valves and control circuits.

Safety analysis update including seismic RCS loop reanalysis would be required.

Cost would exceed $2M and benefit would be much less than 10% reduction in CDF.

55 Install an Reduced frequency of core NEI 05-01 Basis for Screening: For a plant with Excessive independent damage from loss of (Rev A) significant construction already completed, Implementation reactor coolant component cooling water, the estimated cost of implementation Cost. (Table pump seal injection service water, or station would exceed the bounding benefit. 15-2 Case 1) system, with blackout. Hardware, building, facilities support dedicated diesel. would be high cost. ASME, safety grade interface to CVCS. SAMA 56 (reactor coolant pump seal injection system without dedicated diesel) was screened out in Phase II evaluation. Would be considered with other Seal LOCA SAMAs.

77 Provide a passive, Reduced potential for core NEI 05-01 Basis for Screening: For a plant with Excessive secondary-side damage due to loss-of- (Rev A) significant construction already completed, Implementation heat-rejection loop feedwater events. the estimated cost of implementation Cost. (Table consisting of a would exceed the bounding benefit. 15-2 Case 1) condenser and heat Potential change is less than 50% of CDF.

sink. A passive heat removal system using air as the ultimate heat sink would be extremely large and expensive to install.

78 Modify the startup Increased reliability of NEI 05-01 Basis for Screening: Implementation of Excessive feedwater pump so decay heat removal. (Rev A) this SAMA requires a flow path around the Implementation 8

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition that it can be used isolation valves. Also for use during a Cost. (Table as a backup to the station blackout the Standby Feedwater 15-2 Case 1) emergency pump would have to be powered from a feedwater system, diesel generator. For a plant with including during a significant construction already completed, station blackout the estimated cost of implementation scenario. would exceed the bounding benefit.

Would require flowpath from condenser through hotwell pumps, through condensate system and around safety grade isolation valves (or alternate power source to reopen valves and power pumps).

Potential change is less than 50% of CDF.

90 Create a reactor Enhanced debris cool NEI 05-01 Basis for Screening: For a plant with Excessive cavity flooding ability, reduced core (Rev A) significant construction already completed, Implementation system. concrete interaction, and the estimated cost of implementation Cost. (Table increased fission product ($8,750,000, representative of similar 15-2 Case 2 )

scrubbing. nuclear power plants) would yield a benefit of much less than 20% reduction in LERF.

91 Install a passive Improved containment NEI 05-01 Basis for Screening: The source of this Excessive containment spray spray capability. (Rev A) SAMA is the AP600 Design Certification Implementation system. Review submittal. For a plant with Cost. (Table significant construction already completed, 15-2 Cases 2 the cost of implementation ($20,000,000, and 3) representative of similar nuclear power plants) would exceed the bounding benefit.

94 Install a filtered Increased decay heat NEI 05-01 Basis for Screening: For a plant with Excessive containment vent removal capability for non- (Rev A) significant construction already completed, Implementation to remove decay ATWS events, with the estimated cost of implementation Cost. (Table heat. Option 1: scrubbing of released ($5,700,000, representative of similar 15-2 Case 3) 9

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition Gravel Bed Filter fission products. nuclear power plants) would not reduce all Option 2: Multiple of the LATE consequences and would Venturi Scrubber result in a benefit of less than 50%

reduction in LATE.

95 Enhance fire Improved fission product NEI 05-01 Basis for Screening: Enhancements to the Excessive protection system scrubbing in severe (Rev A) EGTS and ABGTS filters to provide Implementation and standby gas accidents. scrubbing for ISLOCA source terms would Cost. (Table treatment system exceed the bounding benefit. This system 15-2 Case 2) hardware and is not currently credited in the PSA and has procedures. limited capability for beyond design basis events due to filter loading concerns.

Upgrading the system for severe accidents would require a redesign with more capable equipment. EPSIL already contains instructions for spraying release points with fire water, which would provide fission product scrubbing. Costs would exceed expected benefit.

97 Create a large Increased cooling and NEI 05-01 Basis for Screening: For a plant with Excessive concrete crucible containment of molten core (Rev A) significant construction already completed, Implementation with heat removal debris. Molten core debris the estimated cost of implementation Cost. (Table potential to contain escaping from the vessel is ($90,000,000 to $108,000,000, 15-2 Cases 2 molten core debris. contained within the representative of similar nuclear power and 3) crucible and a water plants) would exceed the bounding benefit.

cooling mechanism cools the molten core in the crucible, preventing melt-through of the base mat.

98 Create a core melt Increased cooling and NEI 05-01 Basis for Screening: For a plant with Excessive source reduction containment of molten core (Rev A) significant construction already completed, Implementation 10

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition system. debris. Refractory material the estimated cost of implementation Cost. (Table would be placed ($90,000,000, representative of similar 15-2 Cases 2 underneath the reactor nuclear power plants) would exceed the and 3) vessel such that a molten bounding benefit.

core falling on the material would melt and combine with the material.

Subsequent spreading and heat removal from the vitrified compound would be facilitated, and concrete attack would not occur.

99 Strengthen Reduced probability of NEI 05-01 Basis for Screening: For a plant with Excessive primary/secondary containment over- (Rev A) significant construction already completed, Implementation containment (e.g., pressurization. the cost of implementation would exceed Cost. (Table add ribbing to the bounding benefit. 15-2 Cases 2 containment shell). and 3) 100 Increase depth of Reduced probability of NEI 05-01 Basis for Screening: For a plant with Excessive the concrete base base mat melt-through. (Rev A) significant construction already completed, Implementation mat or use an the cost of implementation caused by Cost. (Table 15-alternate concrete reconstruction of the containment building 2 Cases 2 and material to ensure would exceed the bounding benefit. 3) melt-through does not occur.

102 Construct a Reduced probability of NEI 05-01 Basis for Screening: For a plant with Excessive building to be containment over- (Rev A) significant construction already completed, Implementation connected to pressurization. the cost of implementation ($10,000,000 Cost. (Table primary/secondary and up, representative of similar nuclear 15-2 Cases 2 containment and power plants) would exceed the bounding and 3) maintained at a benefit.

11

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition vacuum.

105 Delay containment Extended reactor water NEI 05-01 Basis for Screening: Delay of containment Excessive spray actuation storage tank availability. (Rev A) spray actuation would require reanalysis of Implementation after a large safety analysis. Current safety analysis Cost. Would LOCA. does not allow actuation delay. Cost of re- require analysis and implementation would exceed development the maximum benefit (<.0008 CDF) and NRC approval of new gothic containment model and revised mass/energy release model.

Costs are excessive unless done through an Owners Group cost share with other ice condenser plants. (Table 15-2 Case 1) 106 Install automatic Extended time over which NEI 05-01 Basis for Screening: The estimated cost of Excessive containment spray water remains in the (Rev A) implementing a design change including Implementation pump header reactor water storage tank, reanalysis of the safety analysis is Cost. (Table throttle valves. when full containment considered excessive cost compared to the 15-2 Case 1) spray flow is not needed. risk benefit. Would require development and NRC approval of new gothic containment model and revised 12

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition mass/energy release model. Benefit is less than 1% of CDF. Costs are excessive unless done through an Owners Group cost share with other ice condenser plants.

(proposal in progress) 115 Locate residual Reduced frequency of NEI 05-01 Basis for Screening: For a plant with Excessive heat removal ISLOCA outside (Rev A) significant construction already completed, Implementation (RHR) inside containment. the estimated cost of implementation Cost. (Table containment. ($28,000,000, representative of similar 15-2 Case 5) nuclear power plants) would exceed the bounding benefit. Combine with SAMA 178.

119 Institute a Reduced frequency of NEI 05-01 Basis for Screening: The current cost of Excessive maintenance steam generator tube (Rev A) steam generator eddy current inspection is Implementation practice to perform ruptures. approximately $1million per steam Cost. (Table a 100% inspection generator. The cost of performing 100% 15-2 Case 5) of steam generator inspection including the cost of the added tubes during each outage time would exceed the bounding refueling outage. benefit. SGTR IE reduction in CDF is very small.

120 Replace steam Reduced frequency of NEI 05-01 Basis for Screening: The cost of replacing Excessive generators with a steam generator tube (Rev A) the steam generators at Watts Bar Unit 1 Implementation new design. ruptures. was $221,760,000. This exceeds the Cost. (Table bounding benefit. SGTR IE reduction in 15-2 Case 5)

CDF is very small.

121 Increase the Eliminates release pathway NEI 05-01 Basis for Screening: For a plant with Excessive pressure capacity to the environment (Rev A) significant construction already completed, Implementation of the secondary following a steam the estimated cost of implementation Cost. (Table side so that a steam generator tube rupture. would exceed the bounding benefit. SGTR 15-2 Case 5) generator tube IE reduction in CDF is very small.

13

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition rupture would not cause the relief valves to lift.

122 Install a redundant Enhanced depressurization NEI 05-01 Basis for Screening: Normal and auxiliary Excessive spray system to capabilities during steam (Rev A) pressurizer spray capability is available in Implementation depressurize the generator tube rupture. the current design. The estimated cost of Cost. ASME primary system implementation of a new pressurizer spray safety grade during a steam system would exceed the potential benefit. connections to generator tube SGTR IE reduction in CDF is very small. RCS and rupture. civil/DBA reanalysis would drive costs high.

(Table 15-2 Case 5) 125 Route the Reduced consequences of a NEI 05-01 Basis for Screening: For a plant with Excessive discharge from the steam generator tube (Rev A) significant construction already completed, Implementation main steam safety rupture. the estimated cost of implementation of a Cost. (Table valves through a new structure would exceed the bounding 15-2 Case 5) structure where a benefit. Installation of another structure, water spray would additional SRV tailpipe, and new SRVs, condense the steam larger Steam Gen connections to and remove most accommodate additional piping pressure of the fission drops and remain inside the current safety products. analysis would be costly. SGTR IE reduction in CDF is very small.

126 Install a highly Increased reliability of NEI 05-01 Basis for Screening: For a plant with Excessive reliable (closed decay heat removal. (Rev A) significant construction already completed, Implementation loop) steam the estimated cost of implementation of a Cost. (Table generator shell-side water cooled isolation condenser would 15-2 Case 5) 14

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition heat removal exceed the bounding benefit. Potential system that relies change is less than 50% of CDF. A on natural passive heat removal system using water as circulation and the ultimate heat sink would be extremely stored water large and expensive to install.

sources 129 Vent main steam Reduced consequences of a NEI 05-01 Basis for Screening: The estimated cost of Excessive safety valves in steam generator tube (Rev A) design reanalysis and implementation of Implementation containment. rupture. hardware changes would exceed bounding Cost. (Table benefit. Implementation would also have 15-2 Case 5) negative consequences since the increase in containment pressure would result in containment isolation phase B which would empty the RWST. This would convert the event into a LOCA with consequential challenges. SGTR IE reduction in CDF is very small.

133 Install an ATWS Increased ability to remove NEI 05-01 Basis for Screening: For a plant with Excessive sized filtered reactor heat from ATWS (Rev A) significant construction already completed, Implementation containment vent events. the estimated cost of implementation Cost. (Table to remove decay would exceed the potential benefit; i.e. 15-2 Case 1) heat. <.04 of CDF.

143 Upgrade fire Decreased consequences of NEI 05-01 Basis for Screening: Two and three hour Excessive compartment a fire. (Rev A) regulatory required fire protection barriers Implementation barriers. are installed and maintained. Non Cost. (Table regulatory required two hour fire barriers 15-2 Case 1) are also credited in IPEEE. For a plant with significant construction already completed, the estimated cost of upgrading to 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> fire barriers would exceed the 15

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition potential benefit. Potential SAMAs for FIVE contributors were described in the response to RAI 4d.

166 Create a water- This rubble bed would Cook Basis for Screening: For a plant with Excessive cooled rubble bed contain a molten core significant construction already completed, Implementation on the pedestal. dropping onto the pedestal, the estimated cost of implementation Cost. (Table and would allow the debris ($18,000,000, representative of similar 15-2 Cases 2 to be cooled. nuclear power plants) would exceed the and 3) bounding benefit.

172 Increase Reduces chance of Cook Basis for Screening: For a plant with Excessive containment design containment overpressure significant construction already completed, Implementation pressure. failures. the cost of implementation caused by Cost. (Table reconstruction of the containment building 15-2 Cases 2 would exceed the bounding benefit. and 3) 211 Replace reactor Reduces core damage Cook Basis for Screening: For a plant with Excessive vessel with contribution due to vessel significant construction already completed, Implementation stronger vessel. failure. the estimated cost of implementation Cost. (Table would exceed the bounding benefit. 15-2 Case 1) 214 Reinforce the Seismic failure of the steel Cook Basis for Screening: For a plant with Excessive seismic capacity of structure supporting the significant construction already completed, Implementation the steel structure auxiliary building would the estimated cost of implementation to Cost. (Table supporting the lead to collapse of the reinforce the auxiliary building to 15-2 Case 1) auxiliary building. building. Reinforcing the withstand beyond-design-basis earthquake building potentially levels would exceed the potential benefit.

precludes or lessens this failure mode.

233 Implement The implementation of an Vogtle Basis for Screening: The cost of installing Excessive alternate AC power alternate AC power source an additional EDG has been estimated to Implementation source. would most likely take the be greater than $20 million in the Calvert Cost. (Table form of an additional EDG. Cliffs Application for License Renewal. It 15-2 Case 1) 16

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition This SAMA would help was similarly estimated to be about mitigate LOSP events and $26.09M for both units at Vogtle. As the would reduce the risk per unit cost of approximately $10M to during time frames of on- $13M is greater than the Watts Bar line EDG maintenance. maximum benefit, it has been screened The benefit would be from further analysis.

increased if the additional DG could 1) be substituted for any current diesel that is in maintenance, and 2) if the diesel was of a diverse design such that CCF dependence was minimized.

242 Permanent, This SAMA provides a Wolf Basis for Screening: Local operation of Excessive Dedicated means of limiting the size Creek the TDAFWP is currently proceduralized. Implementation Generator for the of a seal LOCA and This requires a dedicated DG with auto Cost. (Table NCP with Local providing primary side start capability and auto transfer to meet 15-2 Case 1)

Operation of TD makeup through the the 13 minute criteria to prevent seal AFW after 125V installation of a diesel LOCA. Additionally the DG and Charging Battery Depletion. generator that can be Pump lube oil cooling and seal cooling rapidly aligned to the NCP would require CCS and ERCW. The from the MCR. Long term estimated cost of implementation of a secondary side cooling can dedicated DG would exceed the potential be provided through the benefit. This SAMA will be considered operation of the turbine with other Seal LOCA SAMAs under driven AFW pump using consideration if SAMA 58 is shown existing Wolf Creek unreliable. See also SAMA 226.

procedures. This arrangement would make it 17

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition possible to provide adequate core cooling in extended SBO evolutions.

253 Install SG Isolation Installation of primary side Wolf Basis for Screening: For a plant with Excessive Valves on the isolation valves provides Creek significant construction already completed, Implementation Primary Loop Side. an additional means of the estimated cost of implementation Cost. (Table isolating and controlling an would exceed the bounding benefit. 15-2 Case 5)

SGTR event. These valves Would require ASME safety related piping would also eliminate the and valves in additional to verification by need for local action to analysis and testing of the increased flow complete a steam generator resistance. Also seismic reanalysis of the isolation after a tube RCS system. SGTR IE reduction in CDF rupture has occurred. is very small.

261 Guidance to align In the event of a loss of IPE Basis for Screening: The cost to refurbish, Excessive the C-S diesel offsite power followed by complete and license the spare 5th DG was Implementation generator. the failure of both estimated at ~2 to 3 million in 1996. Cost. See #9.

shutdown boards on one Currently the cost is estimated at $7 (Table 15-2 unit, the procedures would million plus labor. The potential benefit is Case 1) be enhanced by adding the much less than 20% reduction in CDF.

guidance to align the C-S Procedures to align the portable DG have diesel generator (i.e., the already been implemented.

fifth diesel generator) to one of the shutdown buses not powered in the accident sequence due to the loss of a normally aligned diesel generator. This alignment could be accommodated by including a reference to the spare diesel generator in 18

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition AOI 35, "Loss of Offsite Power."

270 Delay containment From a severe accident IPE Basis for Screening: The current Watts Bar Excessive spray operation point of view, one potential design basis calculations require sprays to Implementation relative to phase B change, for consideration, initiate at containment phase B conditions. Cost. See #105.

conditions. would be the delaying of This SAMA would require reanalysis of (Table 15-2 spray operations relative to Safety analysis; and the benefit is less than Case 1) the Phase B condition. 1% of CDF. Therefore it is considered Currently, containment cost prohibitive.

sprays actuate immediately in response to a Phase B condition, and air return fans (ARF) actuate after a 10 minute delay. This is currently a requirement of the design basis LOCA where switchover to containment spray recirculation occurs prior to ice melt; thereby limiting pressure increases below containment design pressure. Modular Accident Analysis Program analyses of representative core damage sequences indicate that actuation of the containment sprays while ice remains in the ice condenser has little impact 19

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition on severe accident containment performance and may be detrimental in that operation of the sprays rapidly depletes the inventory of the RWST, making its contents unavailable for vessel injection. Since many scenarios have successful injection but failure at recirculation, the rapid depletion of the RWST due to spray operation accelerates the time to core damage. Therefore, an evaluation balancing the severe accident versus design basis requirements could be made.

274 Replace CCS Improves reliability of RRW Basis for Screening: PD pump removed Excessive pumps with CCS system. Review from CVCS due to problems during initial Implementation positive testing on U1. WBN preference to avoid Cost. (Table displacement PD pumps on other systems. For a plant 15-2 Case 1) pumps. with significant construction already completed, the estimated cost of implementation would exceed the bounding benefit.

287 Increase 0.232 Probability taken from CAFTA Basis for Screening: For a plant with Excessive probability of hot analysis of Sequoyah in IPE significant construction already completed, Implementation 20

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition leg failure prior to NUREG/CR-4551 the estimated cost of implementation Cost. (Table Vessel breach would exceed the bounding benefit. A 15-2 Case 5) given no fundamental change in RCS piping design temperature would be needed to materially change this induced SGTR probability, plus new safety analysis including civil analysis would be required.

Since this change would not reduce the core damage frequency, the expected benefit is limited.

288 Reduce 5.14E-2 Probabilities taken from CAFTA Basis for Screening: For a plant with Excessive probability of NUREG-1570 IPE significant construction already completed, Implementation temperature the estimated cost of implementation Cost. (Table induced SGTRs for would exceed the bounding benefit. A 15-2 Case 5)

SBO sequences fundamental change in RCS/SGTTR with no secondary piping design would be needed to heat sink materially change this probability, likely including new steam generators. SGTR IE reduction in CDF is very small.

289 Reduce 3.81E-2 Probabilities taken from CAFTA Basis for Screening: For a plant with Excessive probability of NUREG-1570 IPE significant construction already completed, Implementation temperature the estimated cost of implementation Cost. (Table induced SGTRs for would exceed the bounding benefit. A 15-2 Case 5) non-SBO fundamental change in RCS/SGTTR sequences with no piping design would be needed to secondary heat sink materially change this probability, likely including new steam generators. SGTR IE reduction in CDF is very small.

290 Reduce probability Probabilities taken from CAFTA Basis for Screening: For a plant with Excessive of rocket mode and NUREG/CR-6427 IPE significant construction already completed, Implementation ex-vessel steam the estimated cost of implementation Cost. (Table 21

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition explosions causing would exceed the bounding benefit. A 15-2 Case 2) early containment fundamental change in Reactor vessel failure cavity design would be needed to materially change this probability.

5 Provide DC bus Improved availability of NEI 05-01 Basis for Screening: Since cross-ties are Very Low cross-ties. DC power system. (Rev A) available at the 480V supplies, and the #5 Benefit. (Table spare battery can be aligned to and supply 15-2 Case 1) any of the 4 buses, this SAMA has very little risk benefit (<2% CDF) Combine with SAMA 258.

16 Improve Increased availability of NEI 05-01 Basis for Screening: Four new inverters Very Low uninterruptible power supplies supporting (Rev A) have been incorporated and a spare is Benefit. (Table power supplies. front-line equipment. already available. PRA modeling changes 15-2 Case 1) to realistically reduce the loss of 120V AC initiating event frequencies has greatly reduced the importance of these supplies.

Benefit is less than 0.1% of CDF.

28 Add a diverse low Improved injection NEI 05-01 Basis for Screening: See response to item Very Low pressure injection capability. (Rev A) 10, RAI 4.e.ii regarding the feasibility of a Benefit. (Table system. similar diverse low pressure injection 15-2 Case 1) system. For a plant with significant construction already completed, the estimated cost of implementation would exceed the bounding benefit.

29 Provide capability Improved injection NEI 05-01 Basis for Screening: See response to item Very Low for alternate capability. (Rev A) 10, RAI 4.e.ii regarding the feasibility of a Benefit. (Table injection via diesel- similar diverse low pressure injection 15-2 Case 1) driven fire pump. system. There is a minimal benefit from this SAMA since it does not provide a recirculation path. Therefore it is not 22

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition considered further. This SAMA is considered cost prohibitive relative to the potential benefit.

47 Enhance the screen Reduced potential for loss NEI 05-01 Basis for Screening: The location of the Very Low wash system. of SW due to clogging of (Rev A) intake on the river is protected from debris Benefit. (Table screens. therefore there is minimal benefit of this 15-2 Case 1)

SAMA (i.e. <1.6% CDF). Combine with SAMA 202 50 Enhance loss of Reduced probability of NEI 05-01 Basis for Screening: Upon receipt of any Very Low component cooling reactor coolant pump seal (Rev A) RCP seal no. 1 outlet temperature high Benefit. (Table water procedure to failure. alarm, AOI-15 & 24 require an RCS 15-2 Case 1) underscore the cooldown after isolation of the CCS path desirability of to the RCP thermal barrier and isolation of cooling down the RCP seal injection. This order of actions reactor coolant is deemed appropriate for overall plant system prior to seal stabilization following a loss of CCS.

LOCA. Enhanced procedure will not affect the risk because of the rapid progression of the seal leak. Therefore, the intent of this SAMA is minimal benefit. This SAMA may be considered with other Seal LOCA SAMAs in Phase II.

53 On loss of essential Increased time before loss NEI 05-01 Basis for Screening: AOI-13 for ERCW Very Low raw cooling water, of component cooling (Rev A) system loss or rupture does not provide Benefit. (Table proceduralize water (and reactor coolant directions to quickly implement loss of 15-2 Case 1) shedding pump seal failure) during CCS procedure AOI-15 if ERCW cannot component cooling loss of essential raw be restored. AOI-13, however, does water loads to cooling water sequences. provide directions to trip all of the RCPs, extend the isolate thermal barrier cooling, cooldown component cooling the plant and cross-tie ERCW if available.

23

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition water heat-up time. There is minimal risk reduction for CCS load shedding since this is a timing issue for recovery of ERCW. The PRA model credits manual alignment of fire protection water to ERCW as a backup... Therefore this SAMA has very low risk improvement benefit.

79 Replace existing Increased probability of NEI 05-01 Basis for Screening: The Watts Bar Very Low pilot-operated successful feed and bleed. (Rev A) success criteria for bleed and feed is two Benefit. (Table relief valves with PORVs only if charging is not available. 15-2 Case 1) larger ones, such Otherwise one PORV is sufficient. Larger that only one is valves would require piping changes, block required for valve changes, and analysis changes.

successful feed and There is a larger probability of leakage bleed. with larger valves. Based on this, this SAMA provides little benefit for the estimated cost.

80 Provide a Increased availability of NEI 05-01 Basis for Screening: Provisions for Very Low redundant train or components dependent on (Rev A) compensatory ventilation is in place for the Benefit. (Table means of room cooling. 480V electric board rooms and margin to 15-2 Case 1) ventilation. room heatup limits exists in the 480V transformer room. Plant chillers are being upgraded based on Freon considerations.

TVA has committed to purchasing new temporary ventilation equipment. See the response to item 11, RAI 4.e.v. This SAMA is considered not cost beneficial due to low risk benefit.

81 Add a diesel Improved diagnosis of a NEI 05-01 Basis for Screening: The diesel generator Very Low building high loss of diesel building (Rev A) building is manned during DG starts, and Benefit. (Table 24

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition temperature alarm HVAC. shiftly operator rounds take temperature 15-2 Case 1) or redundant louver measurements per SI-2. Therefore this and thermostat. SAMA is considered very low benefit.

92 Use the fire water Improved containment NEI 05-01 Basis for Screening: Although there are Very Low system as a backup spray capability. (Rev A) two 2-inch test connections (72-545 & Benefit. (Table source for the 544) that could be used to connect fire 15-2 Case 1) containment spray water to containment spray, this lineup system. bypasses the containment spray heat exchangers and would not remove containment heat. It also cannot recirculate water from the containment sump. The low flow rate would be ineffective for fission product removal.

Therefore this SAMA is considered very low benefit. Combine with SAMA 170.

116 Ensure ISLOCA Scrubbed ISLOCA NEI 05-01 Basis for Screening: The cost of Very Low releases are releases. (Rev A) implementation of this SAMA has not Benefit. (Table scrubbed. One been estimated in detail. A minimum 15-2 Case 2) method is to plug value of $100K for a hardware change is drains in potential assumed for screening purposes. Auxiliary break areas so that building releases are scrubbed by the Aux break point will be Building Gas Treatment System (ABGTS);

covered with however the ABGTS may not be sized for water. ISLOCA releases. RHR suction and discharge lines are in the overhead and therefore would not be submerged.

Contributes <0.1 % to LERF). Therefore this SAMA is considered very low benefit.

Combine with SAMA 237.

124 Provide improved Improved mitigation of NEI 05-01 Basis for Screening: In the latest model, Very Low 25

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition instrumentation to steam generator tube (Rev A) the contribution of steam generator tube Benefit. (Table detect steam ruptures. ruptures to the core damage frequency is 15-2 Case 5) generator tube only .0001. For a plant with significant ruptures, such as construction already completed, the Nitrogen-16 estimated cost of implementation of rad monitors. monitors for each steam generator would exceed the bounding benefit.

131 Add a system of Improved equipment NEI 05-01 Basis for Screening: For a plant with Very Low relief valves to availability after an (Rev A) significant construction already completed, Benefit. (Table prevent equipment ATWS. the estimated cost of installing a relief 15-2 Case 1) damage from valve system (likely well over $1million) pressure spikes is judged to be excessive relative to the during an ATWS. risk benefit since ATWS accounts for only 3.8 % of the total internal event CDF.

137 Provide capability Decreased time required to NEI 05-01 Basis for Screening: Implementation of Very Low to remove power insert control rods if the (Rev A) this SAMA would require reevaluation of Benefit. (Table from the bus reactor trip breakers fail the loss of the loads on the unit boards. 15-2 Case 1) powering the (during a loss of feedwater Training and procedure changes is control rods. ATWS which has rapid estimated to cost more than the potential pressure excursion). benefit. The contribution of ATWS to CDF is 3.8%. Of this fraction roughly 95% is attributable to RCS overpressurization events resulting from inadequate pressure relief within the first couple of minutes. The ability to remove holding power from the control rods would have to be under a time constraint of 1-2 minutes in order to affect the resulting peak pressures. This response time is not feasible and later response times would 26

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition have minimal benefit; i.e. about 0.2% of CDF. Therefore this SAMA is considered very low benefit.

147 Install digital large Reduced probability of a NEI 05-01 Basis for Screening: The FVI of large Very Low break LOCA large break LOCA (a leak (Rev A) break LOCAs to the core damage Benefit. (Table protection system. before break). frequency is less than .0008. For a plant 15-2 Case 1) with significant construction already completed, the estimated cost of implementation would exceed the bounding benefit.

152 Develop Reduced consequences of NEI 05-01 Basis for Screening: An anti barge boom is Very Low procedures for transportation and nearby (Rev A) installed at the intake structure to reduce Benefit. (Table transportation and facility accidents. transportation accidents. There are no 15-2 Case 1) nearby facility identified hazardous barge shipments near accidents. the Watts Bar site. Therefore this SAMA is considered very low benefit.

153 Install secondary Prevents secondary side NEI 05-01 Basis for Screening: The FVI of all Excessive side guard pipes up depressurization should a (Rev A) secondary side breaks, both inside and Implementation to the main steam steam line break occur outside containment, in the current model Cost. (Table isolation valves. upstream of the main steam is just .06. For a plant with significant 15-2 Case 1) isolation valves. Also construction already completed, the guards against or prevents estimated cost of implementation (i.e.

consequential multiple much greater than $700k) would exceed steam generator tube the bounding benefit.

ruptures following a main steam line break event.

167 Enhance air return Provide an independent Cook Basis for Screening: 10 CFR 50.44 Very Low fans (ice condenser power supply for the air analysis shows these fans are a negligible Benefit. (Table containment). return fans, potentially contribution to the containment's ability to 15-2 Cases 2 reducing containment handle a hydrogen burn. Therefore this and 3) 27

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition failure probability during SAMA is considered very low benefit.

SBO sequences.

183 Implement internal Options considered include Cook Basis for Screening: The current modeling Very Low flood prevention 1) use of submersible of flooding concerns in the WBN PRA Benefit. (Table and mitigation MOV operators, and 2) does not indicate a vulnerability to this 15-2 Case 1) enhancements. back flow prevention in item. Therefore this SAMA is considered drain lines. very low benefit.

184 Implement internal Implement improvements Cook Basis for Screening: The current modeling Very Low flooding to prevent or mitigate 1) a of flooding concerns in the WBN PRA Benefit. (Table improvements rupture in the RCP seal does not indicate a vulnerability to this 15-2 Case 1) identified at Fort cooler of the CCW system, item. Therefore this SAMA is considered Calhoun Station. 2) an ISLOCA in a very low benefit.

shutdown cooling line, and

3) an AFW flood involving the need to possibly remove a watertight door.

For a plant where any of these apply, potentially reduces flooding risk.

199 Provide auxiliary Enhances ventilation in Cook Basis for Screening: Normal auxiliary Very Low building vent/seal auxiliary building. building ventilation is not risk significant Benefit. (Table structure. at Watts Bar unit 2. Therefore this SAMA 15-2 Case 1) is considered very low benefit.

222 Establish a Potentially reduces Cook Basis for Screening: There is a limited use Very Low preventive flooding initiating event of expansion joints at Watts Bar and no Benefit. (Table maintenance frequency and the failure indication of a vulnerability. Therefore 15-2 Case 1) program for probability of plant this SAMA is considered very low benefit.

expansion joints, components.

bellows, and boots.

225 Upgrade main Potentially reduces turbine Cook Basis for Screening: Since the turbine trip Very Low 28

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition turbine controls. trip frequency. initiator contributes less than 2% CDF and Benefit. (Table most turbine trips are not related to control 15-2 Case 1) problems, the estimated cost of implementation would exceed the minimal risk benefit from this SAMA. Therefore this SAMA is considered very low benefit.

234 Implement The implementation of an Vogtle Basis for Screening: The WBN design Very Low automatic initiation automatic HPI initiation initiates HPSI on low RCS pressure which Benefit. (Table of HPI on low RCS system would reduce the would result from an RCP seal LOCA. 15-2 Case 1) level (after AC potential for core damage The PRA model does not explicitly include power recovery). from occurring following operator actions to restore the pumps after events where ac power is AC power recovery since this sequence is recovered, but where a seal dominated by non-recovery of AC power LOCA has already sources. Manual start of the pumps after occurred. In these cases, AC power recovery is already RCS level must be restored proceduralized. Including this operator to avoid core damage from action would result in limited risk benefit occurring. and therefore is not analyzed further.

254 Alternate Fuel Oil EDG failures related to Wolf Basis for Screening: Failure of the fuel oil Very Low Tank with Gravity failure of the fuel oil Creek transfer pumps contributes less than 1% Benefit. (Table Feed Capability. transfer pumps are the internal event CDF based on RRW 15-2 Case 1) currently considered to be review. Improvements in the fuel oil unrecoverable in the PSA transfer system are judged to be a minimal model. The installation of risk benefit. The cost of this enhancement a large volume tank at an has been previously estimated to be elevation greater than the $150,000 by Wolf Creek.

EDG fuel oil day tanks would allow for emergency refill of the day tanks in the event of fuel oil transfer 29

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition pump failure.

262 Provide A potential improvement IPE Basis for Screening: The potential Very Low connections for that could be evaluated is a improvement was evaluated and there is Benefit. (Table centrifugal plant change to provide low benefit to aligning a second charging 15-2 Case 1) charging pumps to connections for both pump to ERCW.

the ERCW system. centrifugal charging pumps, on both units, to the ERCW system for lube oil cooling in the event of a loss of CCS cooling to the associated pump.

Currently, this capability is only available for centrifugal charging pump A on Unit 1.

273 Provide a Eliminates single failure RRW Check valve 62-504 is a single failure Very Low redundant path for potential of RWST check Review point for ECCS injection but it contributes Benefit. (Table ECCS suction from valve failure to open. <.00001 to CDF in the SAMA model. The 15-2 Case 1) the RWST around cost of a design change, new hardware and check valve 62- analysis greatly exceeds the potential risk 504. reduction benefit.

277 Replace shutdown Improved reliability of RRW Basis for Screening: The potential Very Low board chillers. shutdown board HVAC. Review improvement was evaluated by reviewing Benefit. (Table the risk reduction worth (RRW) of the 6.9 15-2 Case 1) kV board room ventilation and ventilation recovery. There is low benefit to these ventilation systems. However, these chillers are being upgraded and replaced for other reasons.

284 Improve training Additional training may CAFTA MD and TD AFW pump isolation test Very Low 30

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition for MD AFW reduce assigned error rate IPE restoration errors (WHEMDA_1, Benefit. (Table pump train A or B WHEDA_2, and WHEAFW) can impact 15-2 Case 1) isolation tests AFW system reliability, especially under conditions of loss of a vital instrument bus or vital battery board. Human failure rate was re-evaluated substantially lower after initial identification of this SAMA to recognize that the error must occur on at least two steam generators rather than just the flow path to just 1 steam generator.

Revised contribution is much less than 0.1% of CDF. Estimated cost is $26,773 for enhanced training.

286 Improve training to Additional training may CAFTA Human failure rate was re-evaluated Very Low avoid a TD AFW reduce assigned error rate IPE substantially lower after initial Benefit. (Table isolation test error identification of this SAMA to recognize 15-2 Case 1) that the error must occur on at least two steam generators rather than just the flow path to just 1 steam generator. Revised contribution is much less than 0.1% of CDF. Estimated cost is $26,773 for enhanced training.

296 Improve training Needed to address failure CAFTA Leading cutset involves common cause Very Low and procedures to combinations of DC buses, IPE failure of safeguards actuation signal in a Benefit. (Table respond to loss of vital instrument buses, and sequences where there is a plant trip 15-2 Case 1) both trains of AFW failures of SSPS. without an SI condition (action HAOS3).

actuation signal Event importance markedly reduced to less than 1% now that initiating event frequencies for loss of inverters and battery boards have been lowered.

31

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition 297 Improve remote Valve indication in MCR CAFTA Difficulty to inspect valves are more likely Very Low valve position allows operators to check IPE to be checked if indicated in MCR. Benefit. (Table indication in the realignment Human failure rate was re-evaluated 15-2 Case 1)

MCR for MD substantially lower after initial AFW pump identification of this SAMA to recognize isolation valves that the error must occur on at least two steam generators rather than just the flow path to just 1 steam generator. Revised contribution is much less than 0.1% of CDF 298 Require added Check is to be performed CAFTA Human failure rate was re-evaluated Very Low supervisory check separately from (not IPE substantially lower after initial Benefit. (Table to MD AFW pump concurrent to) the initial identification of this SAMA to recognize 15-2 Case 1) train isolation checks that the error must occur on at least two valve test steam generators rather than just the flow procedure path to just 1 steam generator. Revised contribution is much less than 0.1% of CDF 301 Require added Check is to be performed CAFTA Human failure rate was re-evaluated Very Low supervisory check separately from (not IPE substantially lower after initial Benefit. (Table to TD AFW pump concurrent to) the initial identification of this SAMA to recognize 15-2 Case 1) train isolation checks that the error must occur on at least two valve test steam generators rather than just the flow procedure path to just 1 steam generator. Revised contribution is much less than 0.1% of CDF 302 Improve remote Valve indication in MCR CAFTA Difficult to inspect valves are more likely Very Low valve position allows operators to check IPE to be checked if indicated in MCR. Benefit. (Table indication in the realignment Human failure rate was re-evaluated 15-2 Case 1)

MCR for TD AFW substantially lower after initial 32

Table 15-3. Phase I SAMA Candidates (Continued)

SAMA Number SAMA Title SAMA Discussion Source Phase I Comments Disposition pump isolation identification of this SAMA to recognize valves that the error must occur on at least two steam generators rather than just the flow path to just 1 steam generator. Revised contribution is much less than 0.1% of CDF 33

RAI Response Submittal of June 17, 2011 TVAs responses in this submittal to items 1,2, 3 and 5 have been reviewed and concluded to be unchanged by correcting the total person-rem computed for each release category.

The response to item 4 is updated below in the form of revised tables to account for correcting the total person-rem computed for each release category. The methodology confirmed in the response is again confirmed here. However, the changed total person-rem computed for each release category does affect the tables provided in this response. Changes to Tables 2.a.iv-4, 2.a.iv-6 and 2.a.iv-4a are provided below. The updated tables account for the corrected person-rem values, a correction to the source term consequences for case Early 1B and a very minor change to the consequence results for Early case 1A.

34

Table 2.a.iv RAI Revised Source Terms for Eleven Release Category Cases Case Noble I Cs Te Ba Sr Ru La Ce Frequency Early 1A 8.5E-01 2.2E-02 1.5E-02 1.7E-02 9.1E-03 1.4E-02 9.5E-03 8.4E-03 9.2E-03 35.0%

Early 1B 8.5E-01 1.0E-02 9.0E-03 1.3E-02 8.1E-03 1.4E-02 9.3E-03 8.1E-03 8.1E-03 30.0%

Early 2A 8.5E-01 1.3E-01 7.1E-02 5.5E-02 1.8E-02 1.6E-02 1.0E-02 1.1E-02 1.9E-02 20.0%

Early 2B 8.5E-01 3.2E-01 1.7E-01 1.3E-01 3.4E-02 1.9E-02 1.1E-02 1.6E-02 3.7E-02 15.0%

Bypass 8.5E-01 9.0E-02 4.9E-02 3.6E-02 1.1E-02 1.1E-02 7.2E-03 7.5E-03 1.2E-02 100.0%

Late 1A 8.5E-01 1.1E-02 6.7E-03 7.1E-03 2.7E-03 4.6E-03 2.5E-03 2.3E-03 2.8E-03 6.6%

Late 1B 8.5E-01 5.3E-03 3.7E-03 5.5E-03 2.6E-03 4.7E-03 2.5E-03 2.3E-03 2.6E-03 30.0%

Late 2A 8.5E-01 7.4E-03 4.8E-03 6.0E-03 2.5E-03 4.6E-03 2.5E-03 2.2E-03 2.6E-03 3.4%

Late 2B 8.5E-01 1.7E-02 9.2E-03 9.3E-03 3.3E-03 4.8E-03 2.5E-03 2.5E-03 3.4E-03 60.0%

SERF 1 8.5E-03 2.4E-04 2.6E-04 2.9E-04 3.0E-04 3.4E-04 3.2E-04 3.1E-04 3.0E-04 80.0%

SERF 2 8.5E-03 2.7E-03 2.1E-03 1.8E-03 1.6E-03 1.5E-03 1.5E-03 1.5E-03 1.6E-03 20.0%

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Table 2.a.iv RAI Revised Doses and Economic Consequences for Eleven Release Category Cases Case Total Person-Rem Economic Cost, $

Early 1A 2.20E+06 4.66E+09 Early 1B 1.96E+06 4.23E+09 Early 2A 3.74E+06 7.97E+09 Early 2B 5.68E+06 1.23E+10 Bypass 2.39E+06 5.31E+09 Late 1A 1.09E+06 2.97E+09 Late 1B 8.99E+05 2.77E+09 Late 2A 9.52E+05 2.83E+09 Late 2B 1.19E+06 3.45E+09 SERF 1 2.47E+05 2.96E+08 SERF 2 6.21E+05 1.74E+09 Table 2.a.iv-4a - RAI Revised Weighted Source Terms for Four Release Category Cases Case Noble I Cs Te Ba Sr Ru La Ce Early 8.5E-01 8.4E-02 4.7E-02 4.0E-02 1.4E-02 1.5E-02 9.9E-03 1.0E-02 1.5E-02 Bypass 8.5E-01 9.0E-02 4.9E-02 3.6E-02 1.1E-02 1.1E-02 7.2E-03 7.5E-03 1.2E-02 Late 8.5E-01 1.3E-02 7.2E-03 7.9E-03 3.0E-03 4.7E-03 2.5E-03 2.4E-03 3.1E-03 SERF 8.5E-03 7.3E-04 6.3E-04 6.0E-04 5.6E-04 5.8E-04 5.5E-04 5.5E-04 5.6E-04 RAI Response Submittal of June 27, 2011 The answer provided in this submittal is unchanged by correcting the total person-rem computed for each release category.

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