GO2-11-032, Response to Request for Additional Information for the Review of the License Renewal Application

Response to Request for Additional Information for the Review of the License Renewal Application

ML110330395
Person / Time
Site:	Columbia
Issue date:	01/28/2011
From:	Gambhir S Energy Northwest
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GO2-11-032
Download: ML110330395 (195)

Text

ENERGY NORTHWEST Sudesh K. Gambhir Columbia Generating Station P.O. Box 968, PE04 Richland, WA 99352-0968 Ph. 509.377.83131 F. 509.377.2354 sgambhir@energy-northwest.com January 28, 2011 G02-11-032 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001

Subject:

COLUMBIA GENERATING STATION, DOCKET NO. 50-397 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE COLUMBIA GENERATING STATION, LICENSE RENEWAL APPLICATION

References:

1) Letter, G02-1 0-011, dated January 19, 2010, WS Oxenford (Energy Northwest) to NRC, "License Renewal Application"

6) Letter dated July 1, 2010, NRC to WS Oxenford (Energy Northwest),

"Request for Additional Information for the Review of the Columbia Generating Station License Renewal Application - SAMA Review,"

(ADAMS Accession No. ML101760421)

7) Letter, G02-10-138, dated September 17, 2010, SK Gambhir (Energy Northwest) to NRC, "Response to Request for Additional Information for the Review of the Columbia Generating State License Renewal Application"

8) Letter dated November 10, 2010, NRC to SK Gambhir (Energy Northwest), "Request for Additional Information for the Review of the Columbia Generating Station License Renewal Application - SAMA Review," (ADAMS Accession No. ML102870984)

9) Letter dated December 2, 2010, NRC to SK Gambhir (Energy Northwest), "Request for Additional Information for the Review of the Columbia Generating Station License Renewal Application - SAMA Review," (ADAMS Accession No. ML103330246)

Dear Sir or Madam:

By Reference 1, Energy Northwest requested the renewal of the Columbia Generating Station (CGS) operating license. Via Reference 2, the Nuclear Regulatory Commission (NRC) requested additional information pertaining to the Severe Accident Mitigation Alternatives (SAMA) analysis. In Reference 3, Energy Northwest submitted responses to the Request for Additional Information (RAI) contained in Reference 2.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION LICENSE RENEWAL APPLICATION Page 2 of 2 In References 4 and 5, the NRC requested additional information pertaining to certain responses provided by Energy Northwest in Reference 3. Transmitted herewith in is the Energy Northwest response to the RAIs contained in References 4 and 5. Enclosure 1 contains Amendment 24 to the License Renewal Application (LRA) that was submitted in Reference 1.

Certain responses in Reference 3 relied upon the results of a sensitivity study, which was to be provided at a later date. Transmitted herewith in Attachment 3 is the sensitivity study based upon the Columbia Integrated Full Power Probabilistic Safety Assessment Model Revision 7.1 referred to in Reference 3.

No new commitments are included in this response. A total of sixteen SAMA candidates will be considered for implementation.

If you have any questions or require additional information, please contact Abbas Mostala at (509) 377-4197.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the date of this letter.

Respectffuly,

/SK Gam bhi r ViceG.President, Engineering : List of Acronyms : Response to Request for Additional Information : Sensitivity Study Based upon the Integrated PSA Model Rev. 7.1 :

Amendment 24 to the LRA cc:

NRC Region IV Administrator NRC NRR Project Manager NRC Senior Resident Inspector/988C EFSEC Manager RN Sherman - BPA/1 399 WA Horin - Winston & Strawn D Doyle - NRC NRR (w/a)

BE Holian - NRC NRR RR Cowley - WD

LIST OF ACRONYMS Page 1 of 3 AC Alternating Current ADS Automatic Depressurization System AOC Averted Off-Site Property Damage Costs AOE Averted Occupational Exposure AOSC Averted On-Site Costs APE Averted Public Exposure AR Action Request AST Alternative Source Term

ATWS, Anticipated Transient Without Scram BED Basic Event Data BOC Break Outside Containment BOP Balance of Plant BWR Boiling Water Reactor BWROG Boiling Water Reactor Owners Group CAS Control Air System CCF Common Cause Failure CDF Core Damage Frequency CET Containment Event Trees CGS Columbia Generating Station CIA Containment Instrument Air System CIV Containment Isolation Valve CPT Control Power Transformer CRC Curriculum Review Committee CRD Control Rod Drive CRDM Control Rod Drive Mechanism CST Condensate Storage Tank DC Direct Current DG Diesel Generator (used interchangeably with EDG)

DMA Diesel Mixed Air EAC Executive Authorization Committee EAL Emergency Action Level ECCS Emergency Core Cooling System EDG Emergency Diesel Generator (interchangeable with DG)

EOP Emergency Operating Procedure EPG Emergency Procedure Guideline ER Environmental Report F&Os Fact and Observations FP Fire Protection FPSA Fire Probabilistic Safety Assessment F-V Fussell-Vesely FW Feedwater HEP Human Error Probability HPCS High Pressure Core Spray HRA Human Reliability Analysis HVAC Heating, Ventilation and Air Conditioning IPE Individual Plant Examination IPEEE Individual Plant Examination - External Events

LIST OF ACRONYMS Page 2 of 3 ISLOCA LCO LERF LLOCA LOCA LOOP LPCI LPCS LRA MAAP MACCS2 MCC MLOCA MO MOC MOV MRule MS MSIV MSPI MSO NC-FTO NC-FTRC NDE NPSH NRC NUMARC 00S PCS PDS PRA PRC PSA RAI RAW RCC RCIC rem RFW RG RHR RHRSW RPV RRW RWCU SAG SAMA Interfacing System Loss of Coolant Accident Limiting Condition for Operation Large Early Release Frequency Large Loss of Coolant Accident Loss of Coolant Accident Loss of Off-Site Power Low Pressure Coolant Injection Low Pressure Core Spray License Renewal Application Modular Accident Analysis Program MELCOR Accident Consequence Code System Motor Control Center Medium Loss of Coolant Accident Motor Operator Mechanism Operated Cell Motor Operated Valve Maintenance Rule Main Steam Main Steam Isolation Valve Mitigating System Performance Indicator Multiple Spurious (Equipment) Operations Normally Closed - Fail to Open Normally Closed - Fail to Remain Closed Non-Destructive Examination Net Positive Suction Head Nuclear Regulatory Commission Nuclear Management and Resources Council Out of Service Power Conversion System Plant Damage State Probabilistic Risk Assessment Project Review Committee Probabilistic Safety Assessment Request for Additional Information Risk Achievement Worth Reactor Closed Cooling Reactor Core Isolation and Cooling roentgen equivalent man Reactor Feedwater Regulatory Guide Residual Heat Removal Residual Heat Removal Service Water Reactor Pressure Vessel Risk Reduction Worth Reactor Water Cleanup Severe Accident Guideline Severe Accident Mitigation Alternative(s)

LIST OF ACRONYMS Page 3 of 3 SAT SBO SDC SGT SLC SLOCA SORV SPC SPSA SRV SSEL SW TREQ TS TSW Systematic Approach to Training Station Blackout Shutdown Cooling Standby Gas Treatment Standby Liquid Control Small Loss of Coolant Accident Stuck Open Relief Valve Suppression Pool Cooling Seismic Probabilistic Safety Assessment Safety Relief Valve Safe Shutdown Equipment List (Standby) Service Water Training Request Technical Specifications Plant Service Water

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 1 of 16 BACKGROUND:

The NRC has issued two additional letters requesting information for the SAMA analysis: ADAMS Accession No. ML102870984 dated November 10, 2010, and ADAMS Accession No. ML103330246 dated December 2, 2010. The following table presents a list of the RAI questions and the location of the responses.

Note: All references in this attachment refer to the list of references contained in the cover letter.

RAI Date Location 3.b-1 12/2/10 3.d(i)-1 11/10/10 3.d(ii)-I 12/2/10 Section 2.2 3.i-1 12/2/10 (Corrected LRA page in Enclosure 1) 5.a-1i 12/2/10 5.d-1i 12/2/10 (SAMAs FR-03, OT-07R also evaluated in Attachment 3) 5.1-l i 12/2/10 - included in response to 6.j-1 ii (SAMA FR-08 was also evaluated in Attachment 3) 5.1-1 ii 12/2/10 6.b-1 i 12/2/10 - included in response to 6.j-1 ii (SAMAs AC/DC-02, 03, 15, 16 were also evaluated in Attachment 3) 6.c(i)-1 12/2/10 6.c(ii)-I 12/2/10 (SAMA CW-03 is also evaluated in Attachment 3) 6.h(c,d)-I 12/2/10 (SAMAs FR-07a, 07b also evaluated in Attachment 3) 6.j-1 11/10/10 Section 4.3 and Appendix A Tables A-15, A-16 6.j-lii 12/2/10 and Attachment 3 Section 4.2 and Appendix B Table B-8 6.j-liv 12/2/10 NRC Request:

3.b-1 Given that the use of NUREG/CR-6850 was limited to only the refinement of electrical hot short probabilities, describe the conservatisms remaining in the fire PSA beyond those that may have been associated with the use of NUREG/CR-6850 used to support SAMA analysis.

Energv Northwest Response:

Areas of conservatism exist in the use of full compartment burn-up, rather than more detailed fire scenarios for some risk-significant fire areas. Also, conservative fire ignition frequencies are used. Although a significant amount of detailed fire scenario modeling has been performed for PSA Rev. 6.2, additional detailed scenario modeling of risk significant fire areas was not completed. Detailed fire scenario modeling would allow reduced risk using current plant configuration. An additional conservatism is in modeling of ignition frequencies. Newer industry data for fire ignition frequencies are significantly lower (on the order of a factor of two in some cases) than the fire frequencies used for PSA Rev. 6.2.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 2 of 16 NRC Request:

3.d(i)-l The response states that the "electronic database used to select and locate cables does not include all conduit locations," and that "most, but not all" of the multiple spurious equipment operations (MSOs) that may need to be modeled have been captured and that, for those not captured, the response to RAI 6.j will account for the incompleteness. The response continues to the conclusion that the "model incompleteness is judged to be encompassed by the provided sensitivity analysis," which includes the use of a 9 5 th percentile uncertainty band on the base fire core damage frequency (CDF). (The response to RAI 6.j further cites sensitivity analysis via the 95th percentile approach). As Columbia estimates a fire CDF using an analysis that goes beyond the typical fire individual plant examination - external events (IPEEE),

enhancements to reduce potential conservatisms, as well as enhancements to remove potential non-conservatisms, that might exist in an IPEEE-like estimate of fire CDF should be present. For example, source-target-specific fire scenarios should have been used in lieu of more conservative assumptions of total room burn-up; and hot short probabilities typically of at least 0.3 should have been assumed in lieu of potentially non-conservative lower values. Please describe these enhancements, including those used with regard to compensating for any incompleteness in the cable location database and modeling of MSOs as cited in the response.

Energy Northwest Response:

To respond to this request, a sensitivity study was performed using PSA Rev. 7.1, which integrates Internal Events, Fire and Seismic PSA models and facilitates the use of the upgraded Internal Events Level 1 and 2 models by the Fire and Seismic models. Rev.

7.1 also includes an update of the hot short probabilities to 0.3 for all of the 130 fire-induced spurious operations modeled, with the exception of some spurious operations of air-operated valves within the condensate system where hot short durations were evaluated and modeled (see response to RAI 3.d(ii)-1 in Attachment 3 for further sensitivity results associated with hot shorts).

Modeling of MSOs is an area of incompleteness in the Fire model. Conservative treatment of hot short modeling was used in part to respond to this incompleteness.

Additionally, in response to Enforcement Guidance Memorandum EGM 09-02, plant modifications are in progress to address MSOs in safe shutdown circuits. Once implemented in the plant, a model update will occur. This effort supports, but is separate from the SAMA evaluation process and would be duplicative for safe shutdown components.

Generally, the industry has seen some increase in CDF contribution from inclusion of MSOs in PSAs. The full quantitative impact of inclusion of MSOs for accident mitigating systems is not known at this time. It is estimated that the impact would not be significant enough to impact the SAMA analysis results when the 9 5 th percentile uncertainty factor (multiplier of 2.6 for Fire) is applied to the benefit results.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 3 of 16 The FPSA model (both Rev. 6.2 and the Rev. 7.1 integrated model) contain selected source-target-specific fire scenarios in lieu of more conservative assumptions of total room burn-up. This was primarily performed for the higher risk fire zones. The lower risk fire zones were included in the model using conservative full room burn-up assumptions. A description of the detailed fire modeling is reported in section E5.5.2 of the ER. However, the amount of detailed fire zone modeling using source target methodology is incomplete and further reduction in conservatism is possible. This incompleteness is judged to not be significant enough to result in masking of importance.

Another area of identified incompleteness is the modeling of circuits routed in conduit.

The current Cable and Raceway (Edison) database was reviewed. This database has been upgraded after the issuance of Rev. 6.2 FPSA. This database has been in an update activity during the last two years and has indentified the conduit that was not included in the Rev. 6.2 Fire model. This update provided building and, in most cases, the fire zone locations of the conduits. However, the routing within the fire zone is not exact enough in the database for further refinement without walkdowns and detailed fire modeling within the zone. Nevertheless, the Integrated PSA Model Rev. 7.1 was modified to include fire impacts to the conduits and enclosed circuits and a sensitivity evaluation performed. Refinements at the scenario level in many instances could not be made. That is, conduits whose location was known only at the zone level based on the data in Edison, were assumed to be failed for all fire scenarios within that zone.

Further refinements for this sensitivity evaluation were not possible at this time without walkdowns and additional scenario development. Although this creates very conservative modeling and potential masking of importance of those circuits with more refined detail, the determination of the RRW for SAMA analysis is of value for assessing the incompleteness. The sensitivity evaluation used six existing SAMA cases that are representative of important systems and fire compartments at CGS to determine if the conduit modeling incompleteness would give an indication of impacting the SAMA results. Table 3.d(i)-1 provides the comparative results of these six SAMA cases.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 4 of 16 Table 3.d(i)-1 SAMA Description Original Sensitivity Case RRW (Fire)

RRW (Fire)

Install permanent hardware changes that make it AC/DC-27 possible to establish 500 kV backfeed through 1.615 1.047 the main step-up transformer.

FR-07b Improve the fire resistance of critical cables 1.036 1.000 Install early fire detection in the following FR-09R Reactor Building physical analysis units: R-1 B, 1.183 1.3981 R-1D, R-1J, R-1L, R-1C, R-1K FR-08 Protect RHR and SW cables from fires.

2.284 1.915 FR-12R Install early fire detection in the following 1.141 1.2411 physical analysis units: T-1A, T-12, T-1C, T-1D Install early fire detection in the following FR-11 R physical analysis units: RC-02, RC-03, RC-05, 2.266 1.067 RC-04, RC-07, RC-08, RC-11, RC-14, RC-13, RC-1A 1FR-09R and FR-12R: The increase in RRW was less than the Uncertainty Factor in Table 4-1 The sensitivity evaluation RRWs that are smaller in the modified model is most likely due to lack of refinement in detailed modeling of the fire impacts to conduits that are routed in large zones or span multiple zones. The conservatism is partially masking the tbenefit seen from the individual SAMA candidates. The increase in RRW values

-associated with SAMA candidates for two of the more important fire compartments were within the uncertainty factor of Table 4.1. However, there is not a significant increase in the RRW value that would impact the SAMA results. This fact supports the judgment that the conduit modeling incompleteness in the FPSA model does not impact the SAMA results.

NRC Request:

3.i-1 In the response, Table 3.i-1 (as well as Table E.4-4 in the ER) shows that PDS 2C (Transient with stuck-open SRV or LOCA with loss of containment heat removal and containment failure occurs prior to core damage with the reactor vessel at low pressure) does not apply to the internal events PSA, but does apply to fire PSA, while at the same time PDS 2D (Transient with loss of containment heat removal and containment fails prior to core damage with the reactor vessel at high pressure) applies to the internal events PSA but not the fire PSA. This appears to be inconsistent. Furthermore, it is not clear why the fire PSA does not include fire-induced containment bypass events (see page 54 of the response). Clarify the apparent discrepancy between consideration of PDS 2C and 2D in the fire PSA. Provide justification on why the fire PSA does not include fire-induced containment bypass events.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 5 of 16 Energy Northwest Response:

Table E.4-4 in the ER identified a PDS 2C that was reproduced in the CGS RAI response to 3.i in Reference 3. The reference to PDS 2C has been identified as an error. PDS 2C does not exist in any portion of the CGS PSA model. The values for PDS 2D (Loss of containment decay heat removal, containment failed, high RCS pressure; low pressure injection failed and decay heat removal failed) for the Level 1 Fire were shown inadvertently in the 2C row. The row with the 2C identification will be deleted. Corrected Tables 3.i-1 and 3.i-2 are provided below.

Table 3.i-1 Comparison of Level 1 by PDS for Internal Events and Fire PSA PDS Level 1 Internal Events PSA Level 1 Fire PSA Frequency (/yr)

Percent Frequency (/yr)

Percent 1A1 561 E-08 1.1%

0.OE+00 0.0%

1 A2 8.4E-07 17.5%

8.3E-07 11.2%

1A3A 4.7E-08 1.0%

0.OE+00 0.0%

1A3B 9.8E-08 2.0%

3.2E-07 4.3%

113B01 3.1E-07 6.5%

2.4E-06 32.4%

1C 1.5E-07 3.1%

0.OE+00 0.0%

1G 4.9E-07 10.2%

1.6E-06 21.6%

1 HA 3.5E-08 0.7%

0.OE+00 0.0%

1 HB 4.7E-08 1.0%

7.7E-08 1.0%

213 1.6E-09 0.0%

2.8E-08 0.4%

2D")(2) 5.1 E-07 10.6%

1.5E-06 20.3%

3C 3.OE-07 6.3%

N/A N/A 4BA 1.1 E-07 2.3%

2.7E-10 0.0%

4BL 6.4E-08 1.3%

0.OE+00 0.0%

5 1.5E-07 3.1%

Note 2 0.0%

6A1A 3.OE-07 6.3%

0.OE+00 0.0%

6A1 B 7.4E-07 15.4%

3.7E-07 5.0%

6A2 2.3E-08 0.5%

7.6E-08 1.0%

6B1 3.3E-07 6.9%

2.7E-07 3.6%

6B2A 5.7E-08 1.2%

0.OE+00 0.0%

6B2B 1.4E-07 2.9%

3.7E-08 0.5%

Note (1): PDSs associated with long term Loss of Decay Heat Removal scenarios.

Note (2): Node ISO in the Fire CETs captures the potential for containment bypass events. The node probability is conservatively based on the Internal Events MSIV CCF failure to isolate probability.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 6 of 16 Table 3.J-2 ComDarison of Level 2 LERF by PDS for Internal Events and Fire PSA Level 2 LERF Internal Events PSA Level 2 LERF Fire PSA Frequency (/yr)

Percent Frequency (/yr)

Percent 1A1 5.5E-09 0.8%

0.OE+00 0.0%

1 A2 9.1 E-08 13.9%

9.OE-08 36.6%

1A3A 2.9E-10 0.0%

0.OE+00 0.0%

1A3B 4.3E-09 0.7%

1.3E-07 52.8%

1130___

0.OE+00 0.0%

0.0E+00 0.0%

1C 1.5E-07 23.0%

0.OE+00 0.0%

1G 3.8E-10 0.1%

1.23E-09 0.5%

1 HA 2.7E-1 1 0.0%

0.OE+00 0.0%

1HB 3.6E-11 0.0%

5.97E-11 0.0%

213")

0.OE+00 0.0%

0.OE+00 0.0%

2D~l) 0.OE+00 0.0%

0.OE+00 0.0%

3C 2.3E-10 0.0%

N/A N/A 4BA 1.1E-07 16.8%

2.7E-10 0.1%

4BL 6.4E-08 9.8%

0.OE+00 0.0%

5 1.5E-07 23.0%

0.OE+00 0.0%

6AIA 2.OE-08 3.1%

0.OE+00 0.0%

6A1B 5.OE-08 7.7%

2.5E-08 10.2%

6A2 0.OE+00 0.0%

0.OE+00 0.0%

6B1 0.OE+00 0.0%

0.OE+00 0.0%

6B2A 0.OE+00 0.0%

0.OE+00 0.0%

6B2B 0.OE+00 0.0%

0.OE+00 0.0%

Note (1): PDSs associated with long term Loss of Decay Heat Removal scenarios.

Note (2): Node ISO in the Fire CETs captures the potential for containment bypass events. The node probability is conservatively based on the Internal Events MSIV CCF failure to isolate probability.

Fire induced containment bypass events are addressed in the FPSA model. PDS State 5, which is used to capture LOCA outside containment with failure to isolate the break in the Level 1 PSA, is not used for the FPSA. Instead, the Fire Level 2 CETs contain a first branch node that asks if the containment is isolated. The value used for this branch node is consistent with the value used for the Internal Events node for loss of containment. This value is based on the Internal Events CCF of the MSIVs to isolate.

The assumption is that the most impacting result of a fire to containment isolation would be to cause a major containment isolation pathway to not close or to inadvertently open.

The node for failure of containment isolation for fire events primarily impacts the large-early, non-scrubbed (LEN) release category in the PSA model, thereby maximizing'its importance. This is a modeling simplification for the PSA Rev. 6.2 model.

For FPSA Rev. 6.2, the LERF analysis uses a probability of 7.8E-04 for failure of containment isolation for all PDSs. It is dominated by the CCF of a pair of MSIVs to close, multiplied by the 4 pairs of MSIVs. For FPSA Rev. 7.1, the LERF analysis uses a probability of 2.72E-03 for failure of containment isolation for all PDSs. It is dominated by the probability for pre-existing containment failures.

The only ISLOCA pathway from the containment that contains two in-series MOVs is the RHR shutdown cooling suction line that is isolated by MOVs RHR-V-8 and RHR-V-

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 7 of 16

9. Valve RHR-V-9 is maintained in the closed position during normal plant operation with power removed from the motor via a protected isolation switch maintained in the "ISOLATE" position. Spurious control and power signals resulting from hot shorts cannot cause the valve motor to energize. The de-energized (isolated) power feeder has been routed in a grounded steel conduit to protect it against external three-phase hot shorts. A fire-induced three phase hot short impacting the RHR-V-9 power feeder, per NUREG/CR-6850, is significantly less than the probability for failure of containment isolation modeled in the FPSA.

Thus, the likelihood for a fire-induced ISLOCA is found to be significantly less than the values used for failure of containment isolation.

NRC Request:

5.a-1 i The response states that 72 cost-beneficial industry SAMAs were evaluated.

Of these, 51 SAMAs were determined to not be applicable to CGS, have already been implemented at CGS, or were already considered in the ER.

This suggests that 21 of the 72 SAMAs were further evaluated. In addition, the RAI response states that these "remaining industry cost-beneficial candidates, along with the 4 candidates specifically identified in the RAI, are listed in Table 5.a-1, and an assessment of the applicability to CGS is provided." This suggests that Table 5.a-1 should have 25 SAMA candidate entries, however, the table only provides an assessment of 16 SAMAs.

Clarify the discrepancy between the 25 SAMAs that should have been further considered, and the 16 SAMAs that were further considered in Table 5.a-1.

Energy Northwest Response:

All 72 cost-beneficial industry SAMA candidates were evaluated. A number of the candidates were duplicates of each other. Twenty-one of the SAMA candidates were determined to be not applicable to CGS. Twenty of the SAMA candidates were determined to be already implemented at CGS with an additional one candidate being a duplicate. Ten of the SAMA candidates were already evaluated in the ER with an additional two candidates being duplicates. As such, the remaining eighteen SAMA candidates were further evaluated, which included the four candidates specifically identified in the original RAI 5.a. Of the 18 candidates, two were duplicates, which were omitted from Table 5.a-1, leaving sixteen SAMA candidates.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 8 of 16 NRC Request:

5.d-1 i In the response in Table 5.d-1 there are several basic events (e.g., HS-CIAV-MO30A, HS-CIAV-MO20, CIAHUMNV1 04BH3-F) that were not considered because the fire PSA conservatively does not credit the air accumulators installed at each of the SRV's and so the basic event is judged to not be a realistic contribution to risk. Provide an assessment of what the RRW would be for these events if the air accumulators were credited and whether this would lead to additional SAMA candidates.

Energy Northwest Response:

The basic events, HS-CIAVMO30A, HS-CIAV-MO20, and CIAHUMNV1 04BH3-F were evaluated and a direct approach to assess the benefit from protecting these components from fire through new SAMA cases was performed. Additionally, two SAMA candidates for addressing the benefit of improving the pneumatic components' reliability for the SRVs was also performed to bound the improvement that crediting the air accumulators to the SRVs would provide.

The hot short basic events were evaluated by performing a new SAMA case FR-03 using the integrated PSA Rev 7.1 model. The Fire RRW associated with protecting CIA-MO-30A and CIA-MO-20 from failure (along with three other hot shorts) due to Fire was 1.064. This SAMA was found to be NOT cost-beneficial. See Table B-8 in. Basic Event CIAHUMNV1 04BH3-F was evaluated as part of the new SAMA Candidate OT-07R to improve procedures and operator training to identify systems and operator actions determined to be important from the PSA. See Table B-8.

The existing SAMA candidate CC-08 effectively evaluated the benefit of including the SRV air accumulators in the PSA model by improving the reliability of the most important of the SRVs. SAMA candidate CC-08 evaluated doubling the reliability of the seven ADS valves. The calculated RRW was 1.000, indicating little to no risk improvement. A second existing SAMA candidate IA-05 doubled the reliability of all SRVs and MSIV pneumatic components and produced an RRW of 1.001. Both of these candidates were screened as very low benefit and a cost-benefit analysis was not performed.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 9 of 16 NRC Request:

5.1-1i The proposed SAMA was evaluated using the baseline assumptions and for a sensitivity case assuming a 3% discount rate. Provide an assessment of this proposed SAMA for the uncertainty analysis sensitivity case presented in response to RAI 6.j and follow-up RAI 6.j-1 i.

Energy Northwest Response:

This RAI concerns SAMA candidate FR-08. See response to RAI 6.J-1 ii in the following pages and the sensitivity study in Attachment 3.

NRC Request:

5.1-1 ii Provide the detailed cost-benefit results for this proposed SAMA (i.e., Tables 11-2, 11-3 and 11-4 results).

Energy Northwest Response:

The detailed cost-benefit results (base cost) for SAMA candidate FR-08 are presented in Table 5.1-1 ii-1 below.

Table 5.1-1 ii-1 Case 28 (FR-08) (Cables - RHRSW)

Internal Events Fire Seismic Off-site Annual Dose (rem) 3.68E+00 1.88E+00 6.75E+00 Off-site Annual Property Loss ($)

$6,140

$3,274

$11,106 Comparison CDF 4.80E-06 7.41 E-06 5.25E-06 Comparison Dose (rem) 3.68E+00 8.60E+00 6.75E+00 Comparison Cost ($)

$6,140

$15,547

$11,106.17 Enhanced CDF 4.80E-06 2.08E-06 5.25E-06 Reduction in CDF 0.00%

71.94%

0.00%

Reduction in Off-site Dose 0.00%

78.12%

0.00%

Immediate Dose Savings (On-site)

$0

$459

$0 Long Term Dose Savings (On-site)

$0

$2,002

$0 Total Accident Related Occupational Exposure (AOE)

$0

$2,461

$0 Cleanup/Decontamination Savings (On-site)

$0

$75,076

$0 Replacement Power Savings (On-site)

$0

$110,736

$0 Averted Costs of On-site Property Damage (AOSC)

$0

$185,812

$0 Total On-site Benefit

$0

$188,274

$0 Averted Public Exposure (APE)

$0

$175,360

$0 Averted Off-site Damage Savings (AOC)

$0

$160,168

$0 Total Off-site Benefit

$0

$355,517

$0 Total Benefit (On-isite + Off-site)

$0

$523,791

$0 NRC Request:

6.b-1 i SAMAs AC/DC-02, AC/DC-03, AC/DC-15, and AC/DC-1 6 were evaluated using the baseline assumptions. Provide an assessment of these SAMAs for

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 10 of 16 the uncertainty analysis sensitivity case presented in response to RAI 6.j.

Energy Northwest Response:

See response to RAI 6.j-1 ii in the following pages.

NRC Request:

6.c(i)-1 The response did not answer the question. Provide the time available to recover offsite power with RCIC operating assumed in the baseline PSA without the SAMA.

Energy Northwest Response:

The time available to recover offsite power with RCIC operating assumed in the baseline PSA Rev. 6.2 is eight hours with DC power load-shedding and six hours without load-shedding.

The time available to recover offsite power with RCIC operating assumed in the baseline Integrated PSA Model Rev. 7.1 is seven hours with DC power load-shedding and five hours without load-shedding.

NRC Request:

6.c(ii)-1 The response did not provide the requested information for SAMA CW-03.

Provide a description of the PSA model changes for this SAMA in layman terms.

Energy Northwest Response:

SAMA candidate CW-03 is to replace the ECCS pump motors with air-cooled motors.

The pump motor cooling dependencies modeled for the low pressure ECCS pump motors were set to a low value (1.OE-09). Note: There is no external pump motor cooling for HPCS, so there was no change for the HPCS pump motor.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 11 of 16 NRC Request:

6.h(c,d)-1 Both SAMAs FR-07a and FR-07b provide cost estimates based on assuming that polymeric cables would be replaced by metal-sheathed ("armored?")

ones so as to prevent electrical circuit failure. Depending upon the failure mode involved (short circuit, short to power ["hot short"], open circuit, grounded circuit, etc.), the use of metal-sheathed cables may or may not prevent the assumed electrical failure from occurring (cable degradation can occur due solely to heat transfer even if there is no flame impingement directly on the cable jacketing). Specifically, if the electrical failure could result from degradation WITHIN a specific cable, such as an INTRA-cable hot short, vs. degradation requiring two or more cables to interact, such as an INTER-cable hot short, the use of metal sheathing may not preclude failure.

Discuss the specific electrical failure modes that the SAMA intends to prevent and justify that the use of metal-sheathed cables will prevent these from occurring.

Energv Northwest Response:

Energy Northwest agrees with the RAI discussion on circuit failure modes and the need to ensure that the types of mitigation selected provide the appropriate protection for the circuits involved. It was never intended to indicate that armored cabling could be used for mitigation of all spurious operations. The intent of selecting metal-jacketed (armored) cable as an example in SAMA candidates FR-07a and FR-07b was to address, with a relatively lower cost of implementation, some of the circuit failure modes that cause spurious operations. By using this approach, the estimated cost for implementation of the SAMA candidates was conservatively minimized. Additionally, CGS has actual cost information from installation of armored cable, upon which to base the cost estimate.

Armored cabling is among the least costly of a variety of options to mitigate fire-induced spurious operations. Options such as Meggitt cable, Darmatt wrap or other approved wrapping systems are more expensive. The choice of fire protection enhancement will depend on detailed circuit analyses that include consideration of the circuit logic, the routing, the presence of energized intra-conductors or energized external inter-conductors, the routing through the fire area, and required fire hour rating.

During the implementation phase of these cost-beneficial SAMA candidates, specific protective schemes applicable to the circuit failure mode(s) of concern will be selected.

For example, the criteria for using armored cabling would include: a) the circuit is normally de-energized with no energized intra-cable conductors existing, b) a design basis related fire would cause no change in the component function, and c) no impact on post-fire safe shutdown would occur; that is, if this cable is routed in 3-hour fire areas, it would be routed away from fire-induced falling debris, etc. There is one spurious operation event examined by SAMA candidates FR-07a and FR-07b that could potentially utilize armored cabling in lieu of the more expensive Meggitt-type protection.

Mitigation of other spurious operations would require a Meggitt cabling system or a

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 12 of 16 combination of enclosed raceways with Darmatt or other approved wrapping at increased cost for implementation.

This cost-benefit analysis approach utilized is conservative. Further detailed engineering analysis is not necessary at this time for the SAMA evaluation.

NRC Request:

6.j-1 ii It is unclear how the "Estimated Benefit" in Table 6.j-2 were developed using the uncertainty factors provided in Table 6.j-1. For example, for SAMA AC/DC-27, assuming 7% discount rate, the baseline total benefit from the ER was stated to be $56,044 for internal events, $184,421 for fire events, $0 for seismic events, and $56,044 for other external events, resulting in a total baseline (internal + external) benefit of $296,509. Applying the uncertainty factors from Table 6.j-1 in an uncertainty benefit of $151,319 ($56,044 x 2.7) for internal events, $571,705 ($184,421 x 3.1) for fire events, and $151,319

($56,044 x 2.7) for other external events, resulting in a total uncertainty (internal + external) benefit of $874,343. However, Table 6.j-2 reports the estimated benefit to be $586,944. The uncertainty factors should be applied to all of the elements of the benefit calculation (i.e., APE, AOC, AOE, and AOSC) since each is weighted by CDF. Describe how the uncertainty analysis was performed and justify the "Estimated Benefits" provided in Table 6.j-2.

Energy Northwest Response:

Upon further review of the calculation used to support the Reference 3 response to RAI 6.j, Energy Northwest determined that the uncertainty factors were not applied to all elements of the benefit calculation. The benefits have been recalculated by applying the uncertainty factors to all of the elements of the benefit calculation (APE, AOC, AOE and AOSC). The uncertainty factors from the Reference 3 response to RAI 6.j were utilized in this calculation. The results are presented in Table 6.j-1 ii-1 below.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION.

Page 13 of 16 Table 6.11-11l-1 Estimated 2008 Sensitivity Case Benefit Estimated Cost Conclusion AC/DC-01 Provide additional DC battery

$104,545

$1,799,200 Not Cost Effective capacity.

AC/DC-02 Replace lead acid batteries with fuel

$104,545

$1,040,000 Not Cost Effective cells.

AC/DC-03 Add portable, diesel driven battery

$104,545

$500,000 Not Cost Effective charger to existing DC system.

AC/DC-10 Provide an additional DG.

$717,764

$10,816,000 Not Cost Effective AC/DC-15 Install a gas turbine generator.

$717,764

$2,080,000 Not Cost Effective AC/DC-16 Install tornado protection of gas

$717,764

$2,080,000 Not Cost Effective turbine generator.

AC/DC-23 Develop procedures to repair or

$60,639

$375,000 Not Cost Effective replace failed 4 kV breakers.

Install permanent hardware changes AC/DC-27 that make it possible to establish 500 kV backfeed through the main

$874,344

$1,700,000 Not Cost Effective step-up transformer.

.........2.Reduce common cause failures 00 Cost Efective AC/D-28 between EDG-3 and EDO 1/2.

1976~$0,00

>Cs fetv AC/DC-29 Replace EDG-3 with a diesel diverse from EDG-1 and EDG-2.

$418,599

$4,200,000 Not Cost Effective AT-O5 Add an independent boron injection

$15,550

$800,000 Not Cost Effective AT____05_

system.

Add a system of relief valves to AT-07 prevent equipment damage from

$0

$1,124,864 Not Cost Effective pressure spikes during an ATWS.

AT-1 3 Automate SLC injection in response

$503

$660,000 Not Cost Effective AT-13____

to ATWS event.

AT-14 Diversify SLC explosive valve

$1,006

$370,000 Not Cost Effective operation.

Install additional pressure or leak CB-01 monitoring instruments for detection

$0

$5,600,000 Not Cost Effective of ISLOCAs.

CB-03 Increase leak testing of valves in

$0

$400,000 Not Cost Effective CB-03___ "ISLOCA paths.

CB-08 Revise EOPs to improve ISLOCA

$0

$20,000 Not Cost Effective identification.

CB-09 Improve operator training on

$0

$30,000 Not Cost Effective ISLOCA coping.

Install an independent active or CC-01 passive high pressure injection

$2,573,180

$29,120,000 Not Cost Effective system.

Provide an additional high pressure injection pump with independent CC-02

$2,573,180

$5,200,000 Not Cost Effective

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 14 of 16 Table 6.-1 ii-1i Estimated 2008 Sensitivity Case Benefit Estimated Cost Conclusion CW-03 Replace ECCS pump motors with

$314,158

$1,124,864 Not Cost Effective air-cooled motors.

$314,158

$1,124,864 NotCostEffectiv CW-04 Provide self-cooled ECCS seals.

$314,158

$675,000 Not Cost Effective CW-07 Add a service water pump.

$530,799

$6,136,000 Not Cost Effective FR-03 Install additional transfer and

$647,723

$2,000,000 Not Cost Effective Based upon the results in Table 6.j-1 ii-1, the following SAMA candidates are cost-beneficial: AC/DC-28, CC-03b, FR-07a, FR-07b, FR-08 and HV-02. All of these SAMA candidates will be considered for implementation through the normal processes for evaluating possible plant changes at CGS.

NRC Request:

6.j-1 iv SAMA CC-03b was determined to be cost-beneficial in the uncertainty analysis. Describe Energy Northwest's plans regarding further evaluation of this SAMA and any other SAMAs determined to be cost-beneficial in response to RAIs and the forthcoming sensitivity study.

Energy Northwest Response:

The following processes are used in the review of cost-beneficial SAMA candidates:

" Action Request (AR) Process - Used for tracking procedure revision requests, design change requests, engineering evaluations and training requests Project Proposal, Approval and Funding Process - Used to structure the review and approval of the cost-beneficial SAMA candidates

" Plant Modification and Configuration Control Process - Used for implementing plant modifications Processing of Procedures - Used for implementing procedure changes

" Systematic Approach to Training (SAT) Process-Used for implementing training

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 15 of 16 SAMA Candidates Requiring Plant Modifications:

Each of the cost-beneficial SAMA candidates is entered into the Action Request system.

These SAMA candidates will be AR type EVAL (Evaluation) requiring a technical evaluation. The disposition of the technical evaluation can be a design change, major maintenance, program or other assignment. For actions requiring budget and support to track costs, a project will be established. Projects will follow a three phase project proposal and approval process to address the (1) planning (scope study and project plan development), (2) design, and (3) implementation phases individually. The first step of the process generally involves issue identification and prioritization. Then project funding estimates are developed as part of the project proposal. If the project cost is estimated to be >$250,000, a business case will be prepared and included with the project proposal.

The project proposal is reviewed by the Project Review Committee (PRC) to review the project ranking and determine whether the project should be approved, the appropriate funding level, and the appropriate funding year(s). If the project is approved by PRC and is >$250,000, the project proposal is reviewed by the Executive Authorization Committee (EAC) for final approval. If the project is approved, it will be placed on the Long Range Plan and will be implemented using Energy Northwest processes for project management, configuration control and design changes (plant design change, minor plant design change, or minor alteration). If the project is not approved, the

,project owner will close out any follow-up actions requested by PRC and cancel the AR

'if future approval is not foreseen.

It is possible that a SAMA candidate could be tabled by PRC/EAC awaiting additional information. The information request would likely fall into one of the following categories:

" PRC identified a correction that needs to be made in the SAMA analysis. The impact of the correction needs to be determined.

" PRC identified an alternate solution that will meet the SAMA goal at a lower cost.

The alternate solution needs to be examined.

" PRC requests a PSA sensitivity study to determine the effect of implementing a specified SAMA subset on this SAMA candidate.

" PRC requests a PSA sensitivity study to determine the effect of already approved SAMA candidates on this SAMA candidate.

" PRC requests coordination of this SAMA candidate with related MSPI margin recovery activities. The details of this coordination need to be presented to PRC.

A tabled SAMA candidate will be represented to PRC and EAC (as appropriate) when the requested information has been assembled. At the completion of the review by

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION Page 16 of 16 PRC/EAC, there will be no tabled SAMA candidates. Each PRC/EAC decision and its rationale will be documented in the minutes of the associated PRC/EAC meeting.

SAMA Candidates Requiring Procedure Changes:

Each of the cost-beneficial SAMA candidates is entered into the Action Request system.

If the SAMA candidate consists entirely of a procedure revision for which the technical basis exists, a procedure revision will be initiated to implement the SAMA candidate via the normal procedure review and approval process.

If the SAMA candidate requires further development of the technical basis, additional AR assignments will be made to engineering to support development of the procedure revision. It is possible that the technical basis cannot be developed as described in the SAMA analysis. In this case, the SAMA candidate may not be cost-beneficial and thus will not be implemented. If implementation will continue, a procedure revision will be initiated to implement the SAMA candidate via the normal procedure review and approval process.

SAMA Candidates Requiringq Training:

Requests for training are made using a training request (TREQ). The Training Department reviews all TREQs and assigns them to the appropriate Curriculum Review

Committee (CRC). The CRC is composed of a line management team member

,,appropriate to the scope of oversight responsibility of the CRC, line supervisor(s), job

incumbent(s) and a training supervisor/instructor. The CRC will review the information provided in the TREQ to determine if the TREQ should be approved or if more information is needed in order to disposition the TREQ.

If the training is approved, an AR type TREQ will be initiated to track development and implementation of the training using the SAT process. If more information is needed, the CRC will enter a description of what is needed and generate an AR type CRC assignment to ensure the addition information is collected. The TREQ will be reviewed at the next CRC meeting. If the TREQ is not approved, the reason for not approving the training will be provided and the TREQ will be closed.

SENSITIVITY STUDYBASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 1 of 173 Energy Northwest Sensitivity Study Based Upon the Columbia Generating Station Integrated Full Power Probabilistic Safety Assessment Model Revision 7.1 dated September 2010

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 2 of 173

1.0 INTRODUCTION

In letter G02-1 0-011 (Reference 1), Energy Northwest requested the renewal of the CGS operating license. In a letter dated July, 1, 2010 (Reference 2), the NRC requested additional information pertaining to the SAMA analysis. In letter G02-10-138 (Reference 3), Energy Northwest submitted responses to the SAMA RAIs. Certain responses relied upon the results of a sensitivity study, which was to be provided at a later date, and which was to be based upon the Integrated PSA Model Rev. 7.1. As such, this document augments the responses provided in Reference 3 and provides the results of the sensitivity study. The table below provides a cross-reference of the specific RAI referencing the sensitivity study using Rev. 7.1 of the Integrated PSA Model to the location within this Attachment.

Note: All references in this attachment refer to the list of references contained in the cover letter.

RAI Location Sections 2.0, 2.3, 2.5, 5.0 1.a Appendix A Tables A-i, A-2, A-3, A-4, A-5, A-6, A-7, A-8 Appendix B 1.c Same as 1.a above 1.e Section 2.1 2.c Same as l.a above 2.d Section 2.4 2.f Same as 5.c below 5.a Section 3.2 and Appendix B Section 3.1, 5.0 5.c Appendix A Tables A-9, A-10, A-11, A-12, A-13, A-14 Appendix B 5.d Section 3.2 and Appendix B 5.e Section 3.2 and Appendix B 5.j Section 3.2 and Appendix B 5.1 Section 3.2 and Appendix B 5.m Section 3.2 and Appendix B 6.b Section 3.2 and Appendix B

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 3 of 173 2.0 PSA MODEL REVISION The NRC requested that Energy Northwest provide the following information, which is excerpted from Reference 2:

NRC Request:

1) Provide the following information regarding the Level 1 Probabilistic Safety Assessment (PSA) used for the Severe Accident Mitigation Alternatives (SAMA) analysis:

a.... Identify whether a newer PSA model is available, and if so, provide a brief description of the major changes relative to the PSA Revision 6.2, and provide an assessment of the impact on the results of the SAMA evaluation (e.g., increased benefit or additional SAMAs if the baseline core damage frequency (CDF) has increased; any new candidate SAMAs for newly-identified dominant sequences or risk-significant basic events).

c. ER Section E.5.2 presents a list of seven technical reviews (covering internal events and fire, and Level 1 and Level2) of the PSA (page E-31) an a list of four external peer reviews (page E-32) that contributed to updating the PSA models. Provide the following relative to these reviews

... an assessment of their impact on the SAMA evaluation.

2) Provide the following information relative to the Level 2 analysis:

c. ER Section E.5.5.1 lists peer review findings and other self-identified areas that are in progress for the next revision and characterizes them as not expected to significantly alter the SAMA analysis findings.... Justify the conclusion that the unresolved findings are not expected to significantly alter the results of the SAMA analysis.

Energy Northwest Response:

The basis for the SAMA evaluation presented in Reference 1 is Rev. 6.2 of the PSA. A newer Internal Events PSA Level 1 and Level 2 model, Rev. 7.1, is now available that has been upgraded to comport with RG 1.200 Rev. 2, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities," through the peer review process. This model was not available at the time the original SAMA analysis was performed. The Fire and Seismic PSA models have not been upgraded but have been integrated with the new Internal Events model, including integration with the Internal Events Level 2 CET to achieve consistent release categories.

The source of the changes to the Level 1 and Level 2 Internal Events (including flooding) model were from primarily three sources: (1) a number of peer review F&Os remaining from the 2004 peer review, (2) areas of model incompleteness

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 4 of 173 identified by CGS internal reviews (as identified in section E.5 of the ER) and (3)

RG 1.200 Rev. 2 and associated ASME standard for the Level 1, LERF, and Flooding modeling. A significant PSA upgrade effort was required to incorporate these improvements into Rev. 7.0 of the CGS PSA. Rev. 7.0 also updated the model to include added plant design changes, such as DG-4 and DG-3 cross-connect, procedure changes, and CGS plant initiator history and component failure history. The subsequent peer review of Rev. 7.0 Level 1 and Level 2 Internal Events and Flooding was performed in August 2009 and the report was issued in January 2010. F&Os from this peer review that could significantly impact the model quantification were incorporated in Rev. 7.1. A review of the remaining F&Os associated with Supporting Requirements that were graded as Capability 1 or not met, identified none that should be incorporated that would significantly impact the results of SAMA analysis process.

Energy Northwest has elected to perform a sensitivity study using Rev. 7.1 of the Integrated PSA Model to assess the impact of the model change (including incorporation of previously identified F&Os that were not incorporated into Rev.

6.2 of the PSA) on the results of.the SAMA evaluation presented in Reference 1.

Modeling enhancements made as a result of upgrading the Internal Events PSA to RG 1.200 Rev. 2 resulted in a higher baseline CDF and a lower LERF for the Integrated PSA Model Rev. 7.1 relative to Rev. 6.2. The changes in CDF and LERF are characterized below.

CDF - Integrated PSA Model Rev. 7.1 The Rev. 7.1 CDF (Internal Events) is 7.4E-06/rx-year, which is a 55% increase from the Rev. 6.2 CDF (Internal Events) of 4.77E-06/rx-year. Table A-1 (Internal Events) provides the changes in CDF for Rev. 7.1 relative to Rev. 6.2 for all initiating events, along with a characterization of the changes in terms of plant changes and the Internal Events and Flooding upgrade to RG 1.200 Rev. 2.

Similar tables for CDF comparisons for the FPSA and SPSA are provided in Tables A-1 (Fire) and A-1 (Seismic).

LERF - Integrated PSA Model Rev. 7.1 The Rev 7.1 LERF is 3.6E-07/rx-year, which is a 44% decrease from the Rev.

6.2 LERF of 6.5E-07/rx-year. Table A-2 provides a comparison of LERF contributions for PSA Models Rev. 6.2 and Rev. 7.1 for the Internal Events.

Similar tables for Fire and Seismic are not provided; however, Tables A-1 2 and A-1 4 provide the LERF basic events for Fire and Seismic and present the review for potential SAMA candidates. These tables contain the important initiating events associated with Fire and Seismic LERF. A comparison table for Fire and Seismic similar to Table A-2 would provide little additional insight. The Rev. 7.1 Level 2 analysis for Columbia includes the following enhancements / upgrades:

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 5 of 173 Provides a CET that includes sufficient detail to quantify effects of plant modifications and changes in procedures.

" Establishes added success paths for recovery of degraded core conditions within the reactor vessel (e.g., Three Mile Island Unit 2 events). These paths involve recovery actions during in-vessel core melt progression accidents.

Incorporates the EPG/SAG-based emergency procedures at CGS. This includes containment flooding.

" Interfaces with the BWROG/NUMARC containment safety study to incorporate the latest input on severe accident issues as they affect containment response (e.g., direct containment heating, heat management, seal performance).

" Establishes plant specific deterministic calculations to support the improved success criteria using MAAP calculations as the basis.

Provides a traceable documentation path through the CET so that both qualitative and quantitative insights can be developed.

• Couples the dependencies between Level 1 accident sequences and the Level 2 evaluation by linking the Level 1 and 2 accident sequences.

Incorporates responses to issues identified in NUREG-1 150 "Severe Accident Risks; An Assessment for Five U.S. Nuclear Power Plants" in a more visible manner.

" Expands the CET to encompass an entire spectrum of radionuclide release end states. Plant specific MAAP calculations are used as the basis for characterizing the radionuclide end states for individual Level 2 CET sequences. For example, some CET scenarios that were characterized as LERF in the Rev. 6.2 model were re-characterized as non-LERF in the Rev.

7.1 model (e.g., due to changes in the calculated release timing).

These Rev. 7.1 refinements contributed to the reduction in the LERF frequency relative to Rev. 6.2.

Table A-2 examines important basic events from the Rev. 6.2 LERF quantitative results with RRW values greater than 1.005. This set of basic events produces the greatest potential reductions to Rev. 6.2 LERF if refinements to the modeling were made. Each of the events is examined for potential corresponding refinements that were made for Rev. 7.1, which provides particular insights into the lower LERF produced from Rev. 7.1 relative to Rev. 6.2.

Based on the review documented in Table A-2, the Rev. 7.1 LERF decreased from the Rev. 6.2 LERF primarily because:

1. Rev. 6.2 internal flooding accident sequences were all assumed to go to LERF, which is conservative. In Rev. 7.1, internal flooding accident sequences were assigned to realistic PDSs and accident classes, rather than assigning them all to LERF.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 6 of 173

2. Refinements to the LOCA outside containment modeling produced a net reduction in accident Class 5A and therefore reduction in LERF.

3. Rev. 7.1 modeling refinements reduced the likelihood for the occurrence of an ex-vessel steam explosion that fails containment, which produced a reduction in LERF.

Table 2-1 lists the SAMA candidates identified from a review of the results of the Integrated PSA Model Rev. 7.1 that will be considered for further cost-benefit evaluation. The cost-benefit results are provided in Appendix B.

Table 2-1: New SAMA Candidates Identified from the Integrated PSA Model Rev. 7.1 SAMA Description AT-i 5R Modifications to make use of HPCS more likely for ATWS (such as use of auto-bypass, installing throttle valve, etc.)

FL-07R Protect HPCS from flooding resulting from ISLOCA events.

OT-09R For the non-LOCA initiating events, credit the Z (PCS recovery) function.

FL-04R Add Isolation valves for SW, TSW, and FP in the Control Building for rapid isolation given an internal flood.

FL-05R Add leak detection instruments in drain lines from Control Building compartments to detect leaks and flooding.

FL-06R Add additional NDE and inspections to increase probability of detecting

_ degraded lines in raw water systems in the Control Building.

2.1 TRUNCATION LIMITS The NRC requested that Energy Northwest provide the following information, which is excerpted from Reference 2:

NRC Request:

1) Provide the following information regarding the Level 1 Probabilistic Safety Assessment (PSA) used for the Severe Accident Mitigation Alternatives (SAMA) analysis:

e.... Explain the basis for the truncation limits selected.

Energv Northwest Response:

The PSA model is subject to a number of approximations. One of these approximations arises from cutset truncation. Truncation limits are established to address computational time and computer storage capacity limitations, and assurance is needed to ensure that the appropriate limits are selected. In order to select reasonable and acceptable truncation limits, truncation studies are performed to assess the convergence of the quantified results as a function of the truncation limits imposed. Fault tree and event tree cutsets are truncated at a

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 7 of 173 sufficiently low cutoff value so that dependencies associated with significant cutsets or accident sequences are not eliminated.

There are three distinct truncation limits that were used in the Integrated PSA Model Rev. 7.1 for each of the hazards that comprise the integrated model. In quantifying the model for solution of the SAMA cases, the auto-truncation feature in WinNUPRA was disabled entirely for the Integrated PSA Model Rev. 7.1.

Fault Tree Truncation: For the Internal Events, Fire and Seismic PSA solution, the fault tree truncation limits are assigned to be 1 E-1 0 or lower. This approach provides assurance that when system level cutsets are merged to create sequence level cutsets, any significant shared cutset terms and dependencies, such as support system dependencies, are not truncated during sequence quantification.

Event Tree Truncation: For the Internal Events Level 1 and Level 2 PSA, a sensitivity of truncation limits was performed to gain evidence of convergence toward a stable result. The truncation at 5E-12/yr for the event tree solution shows that it is a reasonable value for base CDF and LERF model quantification.

Convergence in accordance with the ASME standard for the Level 1 model occurs by 1E-11/rx-yr. Convergence in the Level 2 Internal Events model occurs near 5E-1 2/rx-yr. Therefore, a common truncation value was selected as 5E-12/rx-yr for the Internal Events (includes flooding) portion of the Integrated PSA Model Rev. 7.1.

For the Fire and Seismic PSA models, Level 1 and Level 2, a formal sensitivity to demonstrate convergence was not performed. Instead, truncation levels were assigned based on the judgment of the model analysts in order to address the need to ensure no significant accident sequences are inadvertently eliminated and the need to avoid excessively burdensome solution times. The truncations are as follows:

" Fire Level 1: 1 E-1 1/rx-year (six orders of magnitude below the quantified Fire Level 1 result)

" Fire Level 2: 1 E-1 2/rx-year (four orders of magnitude below the quantified Fire Level 2 result)

Seismic Level 1: 1 E-12/rx-year (six orders of magnitude below the quantified Seismic Level 1 result)

Seismic Level 2: 1E-12/rx-year (six orders of magnitude below the quantified Seismic Level 2 result)

Global Truncation: After the individual sequences are all calculated, they are concatenated to yield a global core damage equation, which includes cutsets for all sequences from the associated initiators. In the Integrated PSA Model Rev.

7.1, the global core damage equation truncation limit has been maintained the same as the event tree truncation limit to best preserve the cutset integrity.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 8 of 173 The above truncation limits ensure that significant shared cutset terms and dependencies, such as support system dependencies, are not truncated during sequence quantification. The quantification time for the integrated model for some SAMA cases exceeded seven hours. SAMA results would not be significantly altered by further reduction in truncation limits and would result in significantly longer computational time. Additionally, the applicable RG 1.200 Supporting Requirements, SR QU-B3, was specifically reviewed as part of the Internal Events PSA peer review and graded as "met' by the peer review team.

.2.2 HOT SHORT PROBABILITY The NRC requested that Energy Northwest provide the following information, which is excerpted from Reference 5:

NRC Request:

3.d(ii)-1 Where control power transformers are not present, NUREG/CR-6850 indicates hot short probabilities may be double the 0.3 value (i.e., 0.6).

If the treatment "did not take into account the specific circuit and cabling configurations," what is the basis on which the 0.3 value "was judged to be an appropriate representative... and reasonable for the license renewal application (LRA)?" Furthermore, what is the basis for concluding that the response to RAI 6.j will "account for" this "potential modeling uncertainty?"

Energy Northwest Response:

A sensitivity evaluation was performed to assess the potential incompleteness of the CGS FPSA related to modeling of hot shorts. The Rev. 7.1 FPSA model was modified, and selected SAMA cases, FR-03, FR-07a and FR-07b, were rerun with the modified model. These SAMA cases are appropriate for this sensitivity because these hot shorts have RRW significance and they impact numerous important functions, such as primary offsite power source, SRV and MSIV pneumatic supply components, ADS relief valves, and RHR.

First, for selected hot short events (nine total), a circuit evaluation was performed to verify that a control power transformer (CPT) was present. The hot short probabilities for these nine hot short events remained at 0.3 in the model, which is the highest best estimate value for circuits with a CPT per NUREG/CR-6850 "EPRI/NRC-RES Fire PRA Methodology for Nuclear Power Facilities." For all other hot short events, a circuit evaluation was not performed, and the model was modified to revise the remaining hot shorts to a probability of 0.6, which is the highest best estimate value for circuits without a CPT per NUREG/CR-6850.

This sensitivity evaluation is judged to be a bounding calculation for this model incompleteness.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 9 of 173 The resulting CDFs from the sensitivity evaluation (i.e., the modified model) increased relative to the base (i.e., unmodified) model. The delta-CDF for the three SAMA cases also increased relative to the base. The results are shown in Table 2-2.

As shown on the table, the increase in delta-CDF varies by a factor of 1.1 to 2 for the three SAMA cases. The 95th percentile uncertainty factor for Fire for the Integrated PSA Model Rev. 7.1 is 2.6 (see section 4.2). Thus, the sensitivity evaluation demonstrates that the use of the 95th percentile uncertainty factor for these SAMA candidates in determining their cost-benefit is sufficient to address this area of model incompleteness.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 10 of 173 Table 2-2: Sensitivity Evaluation for SAMA Cases FR-03, FR-07a, FR-07b SAMA Description Base Fire Sensitivity Original Sensitivity Delta-CDF Case CDF Fire CDF Delta-CDF Delta-CDF Factor Increase This SAMA examines protecting CGS circuits from hot shorts for the fire most important hot short events. To obtain the sensitivity delta-CDF, the following hot short probabilities were reduced to zero for the most risk significant hot shorts:

FR-03-1 HS-EAC-TRS 1.37E-05 1.43E-05 8.2E-07 1.3E-06 1.5 HS-CIAV-MO20 HS-CIAV-MO30A HS-ADS-OPEN HS-RHRV-MO-6B This SAMA examines protecting containment vent from fire FR-07a-I damage. To obtain the sensitivity delta-CDF, all equipment for 1.37E-05 1.43E-05 4.1 E-06 4.5E-06 1.1 containment vent (valves, containment air, cables and power I supplies) were assumed to be free from fire damage.

This SAMA examines protecting cables that would disable TR-FR-07b-l S due to hot short. To obtain the sensitivity delta-CDF, the hot 1.37E-05 1.43E-05 4.8E-07 9.6E-07 2

short probability for TR-S was reduced to zero: HS-EAC-TRS

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 11 of 173 2.3 CGS PSA MODEL - LEVEL 2 Appendix A Tables A-3 through A-5 provide the Level 2 release categories and frequencies for Internal Events, Fire and Seismic, respectively, for the Integrated PSA Model Rev. 7.1. These tables are equivalent to ER Tables E.4-3, E.4-5 and E.4-6, respectively, provided for the Rev. 6.2 model in Reference 1. A direct comparison is not meaningful due to the expansion of release categories in the Integrated PSA Model Rev. 7.1 as discussed below.

2.4 UPGRADED MODULAR ACCIDENT ANALYSIS PROGRAM CASES The NRC requested that Energy Northwest provide the following information, which is excerpted from Reference 2:

NRC Request:

2) Provide the following information relative to the Level 2 analysis:

d.... Provide information on the selection of the MAAP case for each release category, in particular how scenarios of less than dominant frequency but larger potential consequences were considered.

Energy Northwest Response:

In Reference 3, Energy Northwest responded to the original NRC RAI associated with the release categories used with the Rev. 6.2 Phase 2 SAMA candidate evaluations. At that time, Energy Northwest also recognized that upgraded MAAP cases have been produced as part of the upgrade of the Internal Events PSA Model Rev. 7.1.

The following information is provided:

• Changesto.MAAP cases used to support the Integrated PSA Model Rev. 7.1 Updated PSA Model Rev. 7.1 release categories Updated MAAP cases used to support the Level 3 SAMA evaluation for this sensitivity study Changes to MAAP Cases Used to Support Internal Events PSA Model Rev. 7.1 In support of the Internal Events PSA Model Rev. 7.1, the CGS plant specific MAAP 4.0.4 parameter file was reviewed and revised to update parameters that represent the current CGS configuration (e.g., 3486 MWth power level and ATRIUM-10 core). Approximately 50 MAAP runs originally used to support PSA Model Rev. 6.2 were re-run using the updated CGS MAAP 4.0.4 parameter file.

Furthermore, approximately 100 additional MAAP runs were performed to support the development of the Internal Events PSA Model Rev. 7.1 using the

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 12 of 173 updated CGS MAAP 4.0.4 parameter file. The additional MAAP runs supported the development of Level 1 PSA success criteria and HRA timings and the Level 2 release category definitions and HRA timings.

Updated PSA Model Rev. 7.1 Release Categories The Level 2 release categories used in support of Rev. 6.2 of the PSA (and the ER) were defined based on the following:

Containment Failure Mode (Large or Small) (i.e., failure size equivalent of 6 inch diameter or greater is Large)

" Time of Containment Failure (Early or Late) (i.e., release at 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> or less is Early)

" Scrubbing of Fission Product (Scrubbed or Non-scrubbed) (i.e., Csl release of 0.1 or greater is Non-scrubbed)

For PSA Model Rev. 6.2, the LEN category (Large, Early release, Not scrubbed) was modeled to correspond to the NRC definition of LERF.

For the Integrated PSA Model Rev. 7.1, the Level 2 CET structures were completely upgraded and Level 2 release categories were completely redefined.

Table 2-3 provides the revised release severity and timing classifications. For example, the definition for the "Early" time category has been changed from "Less than 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />" in Rev. 6.2 to "Less than 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />" in Rev. 7.1 based on the latest CGS Emergency Action Levels (EALs) for declaring a General Emergency and the latest evacuation time estimates. The High/Early (H/E) release category (i.e., greater than 0.1 CsI release magnitude and less than 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> release timing) is modeled to correspond to the NRC definition of LERF. The release categories assigned to individual Level 2 CET sequences are based on the updated Level 2 MAAP runs to support the Integrated PSA Model Rev. 7.1.

Updated MAAP Cases Used to Support Level 3 SAMA Evaluation Updated MAAP cases have been selected to support the Level 3 SAMA analysis based on the Integrated PSA Model Rev. 7.1. Table 2-4 provides a summary of the updated MAAP cases selected to represent the nine (9) updated release category definitions provided in Table 2-3. (Note: The "Late" time category is not used for the Integrated PSA Model Rev. 7.1). For the High/Early release category, case CGS080523 is representative of a break outside containment (BOC) sequence.

The updated MAAP cases shown in Table 2-4 have been chosen based on a detailed review of the Rev. 7.1 Internal Events PSA model quantitative contributors to each of the release categories. A quantitative weighted evaluation was performed based on the dominant cutset contributors and the

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 13 of 173 associated MAAP cases for individual release categories. For example, the High/Early release category includes many contributors with a wide variety of associated MAAP cases ranging from Csl release fractions of 0.1 up to 0.93 (i.e.,

BOC scenario MAAP case CGS080523 mentioned above). The quantitative weighted evaluation considered the following:

0 One of the dominant contributors to the Internal Events High/Early frequency is Class 5 (BOC sequence) at 1.36E-07/yr. The Class 5 MAAP case is CGS080523 with a Csl release of 0.93. The other dominant contributors to the Internal Events High/Early frequency are Class 4BA and 4BL (ATWS sequences) at 1.79E-07/yr. The ATWS High/Early frequency is dominated by wetwell water space failures with successful RPV depressurization. This ATWS scenario is similar to MAAP case CGS080521 with a Csl release of 0.19. A Csl weighted average of Class 5 and 4A for these MAAP cases is:

[1.36E-07x0.93 + 1.79E-07x0.19] - 3.15E-07 = 0.51. This Csi value is close to the value for Class 4A MAAP case CGS080518, which has a CsI release of 0.58.

0 Timing: The General Emergency is declared at 45 min for Class 4. MAAP Case CGS080518 shows containment failure at 8 minutes with core damage at 59 minutes such that the release for Class 4 is in the Early timeframe. In addition, the General Emergency is declared at approximately 17 min for Class 5. MAAP Case CGS080523 shows that core damage occurs at approximately 21 minutes such that the release for the BOC scenario is in the Early timeframe.

Case CGS080523 was ultimately selected for the High/Early release category based on the high contribution of BOC and ISLOCA containment bypass sequences to the Rev. 7.1 Internal Events PSA results. In addition, containment bypass events represent the dominant contributor to the Rev. 7.1 Level 2 external events Seismic PSA model results.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 14 of 173 Table 2-3 AND TIMING CLASSIFICATION SCHEME(1 )

RELEASE SEVERITY Release Severity Classification Cs Iodide % in Category Release High (H)

Greater than 10 Medium or Moderate 1 to 10 (M)

Low (L) 0.1 to 1 Low-low (LL)

Less than 0.1 No iodine (OK) 0 Release Timing Time of Initial Release (2 Relative to Time for Classification General Emergency Category Declaration Late (L)(3 Greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Intermediate (I) 3 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Early (E)

Less than 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />(4)

RADIONUCLIDE RELEASE CATEGORIES DERIVED FOR COLUMBIA GENERATING STATION Time of Magnitude of Release Release H

M L

LL E

H/E M/WE L/UE

.LL/E I

H/I M/I L/I LL/I L (`

H/L M/L L/L LL/L (1) The combinations of severity and timing classifications results in one OK release category and 12 other release categories of varying times and magnitudes.

(2) The cue for the General Emergency declaration is taken to be the time when EALs are exceeded.

The declaration of the General Emergency begins the time for evacuation.

(3) The "Late" time category is not used for the Integrated PSA Model Rev. 7.1.

(4) Evacuation time for the Columbia EPZ is found to be less than 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 15 of 173 Table 2-4: Summary of Updated Rev 7.1 MAAP Runs to Use as Input to MACCS2 Calculations MAAP CGS Cs e

CGS GE Release Category AA 2

Representative Case Description Accidents Release D

)5)

RlaeCtgr(

Cases(2 class (3)

Fraction (4)

Dc.(r MSIV Closed, No RPV Injection, No OK - Containment Intact CGS080524 Depressurization, SPC and Sprays Available, 1A2 3.6E-6 0.75 Containment Intact, 3BOC, LLOCA on MS line, No RPV Injection, No SPC High/Early (LERE-BOC)

CGS080523 or Sprays 5

0.93 0.28 SBO, MSIV Closed, RCIC for 4 hr until battery High/Intermediate CGS080530 depletion, No Depressurization, No SPC or Sprays, 6B2 0.25 1.25 2ft Drywell Failure ATWS with SLC Failure, MSIV Closed, RCIC, CRD, and LPCI Available, 7 SRVs at Top of Active Fuel, 1 4BA 9.5E-3(6 )

0.75 Moderate/Early CGS080519 Loop SPC Available, No Sprays, 2ft2 Wetwell Air Space Failure Moderate/intermediate CG S08051 1 t MSIV Closed, LPCS Available, 7 SRVs at -183", No 11BO 1.6E-2 25.85 SPC or Sprays, 2ft2 Drywell Failure Low/Early CGS080505a MSIV Closed, No RPV Injection, 7 SRVs at -183", No 1G 2.1E-2 0.75 SPC or Sprays, Containment Isolation Failure Low/intermediate CGS08051 1 MSIV Closed, LPCS Available, 7 SRVs at -183", No 11B0 1.6E-2 25.85 SPC or Sprays, 2ft2 Drywell Failure LLOCA, No RPV Injection, Containment Flood with Low Low/Early CGS080529 FP System at RPV Failure, No SPC or Sprays, 3C 3.4E-4 0.25 Containment Vent Available (lft2)

MSIV Closed, No RPV Injection, 7 SRVs at -183",

Low Low/Intermediate CGS080509 Sprays Available, No SPC, 28in2 Wetwell Air Space 1G 2.OE-4 0.75 Failure Notes

ý7'CGS Release category is based on the Integrated PSA Model Rev. 7.1 Level 2 model.

(2)

CGS MAAP case is the representative case for corresponding release category. Case CGS050851 it is used for M/I and also for LI release bins. The conservatism associated with this case for the L/I bin is acceptable because the LI bin frequency is very low.

(3)

CGS accident class designation based on CGS naming convention.

(4) MAAP Csl release fraction at the end of the run.

(5)

CGS General Emergency declaration time.

(6)

Csl value is slightly below the typical 1 E-02 moderate magnitude definition. This MAAP case is judged most reflective of the driving sequences for this bin and is therefore judged appropriate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 16 of 173 2.5 CGS PSA MODEL - LEVEL 3 Base case sensitivity results generated by the Integrated PSA Model Rev. 7.1 for Internal Events, Fire, and Seismic (per release category) are reported in Appendix A Tables A-6, A-7 and A-8, respectively. These tables show the estimated population dose (whole body dose in person-rem/year) and the economic impact in dollars/year. These tables are equivalent to ER Tables E.7-1, E.7-2 and E.7-3, respectively, provided for the Rev. 6.2 model in Reference 1.

3.0 SAMA CANDIDATE SELECTION 3.1 LEVEL 1 AND 2 BASIC EVENTS IMPORTANCE LISTS The NRC requested that Energy Northwest provide the following information, which is excerpted from Reference 2:

NRC Request:

2) Provide the following information relative to the Level 2 analysis:

f. The ER does not provide an importance list of either Level 1 or Level 2 basic events and so it is not possible to ascertain the significance of recovery events or operator actions in the PSAs. Discuss the extent to which recovery of systems or operator actions following the onset of core damage is credited in the Level 2 assessment and how recovery is modeled.

5) Provide the following with regard to the SAMA identification and screening process:

c.... Provide a basic events importance list, in decreasing order of risk reduction worth (RRW), for the Level 1 and Level 2 internal, fire and seismic PSA results that includes a description of each basic event, identifies the RRW and probability of each basic event, and identifies the SAMA(s) that address each basic event and how. Provide the information for all basic events having an RRW benefit value greater than the minimum cost of a procedure change at CGS.

Energy Northwest Response:

Basic events importance lists are presented in Appendix A Tables A-9 through A-14 in decreasing order of RRW for the Level 1 and Level 2 Internal Events, Fire and Seismic PSA results from Rev. 7.1 of the Integrated PSA Model.

The basic event importance lists are truncated at an RRW importance value estimated to provide a maximum cost-benefit equal to the lowest cost of a procedure change at the plant. A simple procedure change is judged to be the

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 17 of 173 lowest cost SAMA candidate possible. A value of $12,000 is conservatively chosen as the lowest cost for implementing a procedure change. Procedure changes of this nature need no engineering calculations or significant training development.

The cost-benefit versus RRW assumes that cost-benefit is directly proportional to the reduction in CDF. Cost is not perfectly correlated with CDF due to the fact that different scenarios, even with the same CDF, will result in different distributions of release categories. It is judged that this correlation provides a reasonable estimate of potential benefit. When coupled with what is judged to be a low cost for a procedure change, this provides a strong confidence that cost-effective SAMA candidates will be captured.

In addition to the cost estimate for a simple procedure change, an estimate is made for the lowest cost for which a simple plant hardware change can be made.

It is conservatively estimated that any plant hardware change cannot be implemented for less than $100,000.

Each of the basic events with RRW importance values equivalent to an estimated cost-benefit equal to or greater than the cost of a simple procedure change have been dispositioned as follows:

• Any SAMA candidates from the original cost-benefit analysis that address the basic event have been identified, Any basic events that require a plant hardware fix and has a calculated RRW equating to less than $100,000 in cost-benefit are screened from further consideration, and For all remaining basic events at least one SAMA candidate is created.

The estimated benefit based on RRW uses the following maximum attainable benefit for the three categories of events:

Table 3-1: Maximum Benefit by Hazard Total Benefit Internal Events

$500,446 Total Benefit Fire

$863,256 Total Benefit Seismic

$436,020

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 18 of 173 Based on the above maximum attainable benefits, the estimated benefits based on RRW by hazard have been developed. Table 3-2 provides a representative selection of estimated benefits. The following formula is used for deriving the estimated benefit based on RRW:

EB(BE)= Bt x (1 - 1/RRW) where:

EB(BE)

BtRRW

= The estimated benefit based on a basic event

= The total benefit for the hazard (Internal Events) from Table 3-1

= The RRW for the basic event from the PSA, by hazard, assuming the basic event failure probability is reduced to zero.

Similar formulas are used for development of the estimated benefit based on RRW for the fire and seismic hazards.

The RRW for the Level 2 PSA basic events may be calculated based on LERF rather than CDF. Additional conservatism is added by treating Level 2 PSA basic event RRW values based on LERF as if they were based on CDF (i.e., the use of Bt significantly overstates their benefit), and the degree of conservatism could be large.

Table 3-2: Estimated Benefit based on RRW for Basic Event Screening RRW Internal Events Fire Seismic (Benefit by CDF)

(Benefit by CDF)

(Benefit by CDF) 1.01

$4,954.91

$8,547.09

$4,317.03 1.015

$7,395.75

$12,757.48

$6,443.65 1.02

$9,812.67

$16,926.59

$8,549.41 1.025

$12,206.00

$21,055.02

$10,634.63 1.03

$14,576.10

$25,143.38

$12,699.61 1.04

$19,247.92

$33,202.15

$16,770.00 1.05

$23,830.76

$41,107.43

$20,762.86 1.06

$28,327.13

$48,863.55

$24,680.38 1.07

$32,739.46

$56,474.69

$28,524.67 1.08

$37,070.07

$63,944.89

$32,297.78 1.09

$41,321.23

$71,278.02

$36,001.65 1.1

$45,495.09

$78,477.82

$39,638.18 1.15

$65,275.57

$112,598.61

$56,872.17 1.2

$83,407.67

$143,876.00

$72,670.00 1.25

$100,089.20

$172,651.20

$87,204.00 1.3

$115,487.54

$199,212.92

$100,620.00

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 19 of 173 Table 3-3 lists the SAMA candidate identified from a review of the Level 1 and Level 2 basic events importance lists that will be considered for further cost-benefit evaluation. The cost-benefit results are provided in Appendix B.

Table 3-3: New SAMA Candidates Identified from Basic Events Importance Lists SAMA Description CB-1OR I Provide additional NDE and inspections of MS pipinq in Turbine Building 3.2 SAMA CANDIDATES IDENTIFIED IN G02-10-138 (REFERENCE 3)

Several of the RAI responses in Reference 3 identified additional SAMA candidates that would be evaluated for cost-benefit using the Integrated PSA Model Rev. 7.1. Table 3-4 identifies the specific RAI responses and additional SAMA candidate identifiers. These SAMA candidates have been considered for cost-benefit evaluation. The results are provided in Appendix B.

Table 3-4: New SAMA Candidates Identified G02-10-138 (Reference 3)

RAI SAMA Description of Potential SAMA Examine the potential for operators to control RFW and avoid a reactor FW-05R titrip CC-26R Install hard pipe from diesel fire pump to vessel FL-05R FL-04R Improve control building flooding scenarios FL-06R Backfeed the HPCS system with SM-8 to provide a third power source 5.a CC-24R frHC for HPCS CC-25R Enhance alternate injection reliability by including RHRSW and fire water crosstie in maintenance program Increase Fire Pump House Building integrity to withstand higher winds OT-10R so the fire system will be capable of withstanding a severe weather event OT-08R Install explosion protection around CGS transformers 5.a OT-07R Improve procedures and operator training to identify systems and 5.e operator actions determined to be important from the PSA 5.d FR-09R Install early detection for FRIJ (physical analysis unit R-1J)

Install early detection for FR1 D (physical analysis unit R-1 D)

Install early detection for FW14 (analysis unit RC-14)

Install early detection for FW04 (analysis unit RC-04)

Install early detection for FWl 1 (analysis unit RC-1 1)

Install early detection for FW03 (analysis unit RC-03)

FR-i 1 R Install early detection for FW08 (analysis unit RC-08)

Install early detection for FW05 (analysis unit RC-05)

Install early detection for FW02 (analysis unit RC-02)

Install early detection for FW13 (analysis unit RC-13)

Install early detection for FW1A (analysis unit RC-1A)

FR-10R Install early fire detection in the Control Room (RC-10)

AC/DC-30R Provide an additional DG diverse from DG-1 and DG-2 FR-12R Install early detection for FT1A (physical analysis unit T-1A)

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 20 of 173 Table 3-4: New SAMA Candidates Identified G02-10-138 (Reference 3)

RAI SAMA Description of Potential SAMA Install early detection for FT12 (physical analysis unit T-12) 5.j SR-05R Increase seismic ruggedness of MCC-7F and MCC-8F 5.1 FR-08 Improve the fire resistance of cables to RHR and SW 5.m FW-04 Add a motor-driven FW pump AC/DC-02 Replace lead-acid batteries with fuel cells (SAMA previously subsumed)

Add a portable, diesel-driven battery charger to existing DC system 6.b (SAMA previously subsumed)

AC/DC-15 Install a gas turbine generator (SAMA previously subsumed)

AC/DC-16 Install tornado protection on gas turbine generator (SAMA previously subsumed) 4.0 SENSITIVITY CASES Energy Northwest has determined that the sensitivity cases of 3% discount rate and 9 5 th percentile factor for CDF are the leading sensitivity cases from the original group of SAMA candidates considered for further evaluation. As such, it is appropriate to run sensitivity cases associated with Rev. 7.1 of the PSA using the 3% discount rate and the 9 5 th percentile factor for CDF.

4.1 3% DISCOUNT FACTOR The first sensitivity case investigates the sensitivity of each analysis case to the discount rate by assuming a lower discount rate of 3% per year. As discussed in Section E.8 of the ER, the base discount rate is 7% per year. The results of this sensitivity case are presented in Appendix B Table B-8 as Sensitivity Case #1.

4.2 9 5 th PERCENTILE FACTOR FOR CDF The second sensitivity case investigates the impact of using uncertainty factors for Internal Events, Fire and Seismic based on the 9 5 th percentile CDF for each analysis. The uncertainty factors are derived from the ratio for the 9 5 th percentile to the mean point estimate for Internal Events, Fire and Seismic CDF. Table 4-1 provides the uncertainty factors used. The results of this sensitivity case are presented in Appendix B Table B-8 as Sensitivity Case #2.

Table 4-1: Uncertainty Factors Uncertainty Factors Internal Events 2.4 Fire 2.6 Seismic 3.0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 21 of 173 4.3 APPLICATION OF UNCERTAINTY TO PHASE 1 SCREENING In Reference 4, the NRC requested that Energy Northwest provide the following information:

NRC Request:

6.j-1 The uncertainty analysis presented in response to this RAI did not re-evaluate the Phase 1 SAMAs using the maximum uncertainty benefit (from eliminating all internal and external risk) from' applying the uncertainty factors provided in Table 6.j-1. Specifically, the maximum baseline benefit in the ER is reported to be $1.9M, while applying the Table 6.j-1 uncertainty factors would increase the maximum benefit to

$5.6M (NRC staff estimate). Provide an assessment of each Phase 1 SAMA eliminated using Screening Criterion D and E to determine whether any Phase 1 SAMAs originally screened should have a Phase 2 cost-benefit evaluation performed. Provide a Phase 2 cost-benefit evaluation for any SAMA not screened.

Energy Northwest Response:

Section E.12 in the ER provided a qualitative justification for not applying the 9 5 th percentile uncertainty to Phase 2 SAMA candidates. RAI 6.j in Reference 2 requested that an additional sensitivity analysis associated with the CDF uncertainty be applied to the Phase 2 SAMA results. Energy Northwest provided the requested sensitivity analysis in Reference 3. In Reference 4, the NRC requested that the CDF uncertainty be applied to the Phase 1 screening of potential SAMA candidates. NEI 05-01, "Severe Accident Mitigation Alternatives (SAMA) Analysis Guidance Document," does not specifically require that uncertainty be applied to Phase 1 screening; however, such an application has merit and would confirm that no SAMA candidates were inadvertently screened using the qualitative method for judging the candidates' potential cost-benefit.

The two criteria identified in NEI-05-01 that would be most impacted by applying the 9 5 th percentile uncertainty factor to Phase 1 screening are Criterion D (Excessive Implementation Cost) and Criterion E (Very Low Benefit).

Table E.10-1 in the'ER presented the results of the Phase 1 SAMA candidate screening using the criteria defined in section E.10.1 through E.10.5. As requested, each of the SAMA candidates screened as either Criterion D or Criterion E have been reevaluated using an RRW benefit related to the maximum benefit obtained and applying the uncertainty factors based on the 9 5 th percentile CDF uncertainty of each hazard of the Integrated PSA Model Rev. 7.1.

In order to evaluate most of the SAMA candidates screened as Criterion E, the PSA modeling is modified to represent the candidate's improvement and to develop an RRW based on its improvement of the specific hazard or hazards that are affected (i.e., base-CDF for each hazard divided by improved-CDF for the

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 22 of 173 hazard due to the SAMA candidate). Once the RRW is established for a SAMA candidate, its benefit (multiplied by the 9 5 th percentile uncertainty factor) can be derived and then assessed as to whether it is below the cost of a procedure change or a small design change, or whether the cost of implementation greatly exceeds the RRW uncertainty benefit such that a further evaluation in Phase 2 is not required. If the SAMA candidate affects more than one hazard, the benefit for each hazard (adjusted for the 9 5 th percentile uncertainty) is added to produce a final uncertainty benefit for screening consideration.

This approach provides a more quantitative approach for the Phase 1 Criterion E screening basis. There is good correlation between RRW benefit and Phase 2 SAMA benefits to justify this approach to Phase 1 screening. This correlation is demonstrated in the following table for four specific SAMA candidates.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 23 of 173 Table 4-2: Comparison of Phase 2 Benefit Results to RRW Benefits, SAMA Phase 2 Benefit with uncertainty RRW RRW Benefit (See Table B-8) with uncertainty Fire 1.43

$675,000 FR-07a Other 1.43

$675,000 Note 1 LERF 1.000 0

$839,005 Total

$1,350,000 Int. Events 1.12

$129,000 Fire 1.15

$285,000 CW-07 Seismic 1.00

$1,000 Note 2 Other 1.12

$129,000 LERF (fire) 1.255

$456,000

$475,184 Total

$1,000,000 Int. Events 1.005

$6,000 Fire 1.000 0

AC/DC-01 Seismic 1.001

$1,500 Note 3 Other 1.005

$6,000 LERF 1.000 0

$8,125 Total

$13,500 Int. Events, 1*

$66,000 Fire

.12.

$42,0*00 AC/DC-23 Seismic 1.00 0

Note 3 Other 1.06

$66,000 LERF 1.0015

$50,000

$173,164 Total

$224,000 (1)

SAMA candidate FR-07a has a Phase 2 calculated benefit (with 95th percentile uncertainty factor) of $839,005 (see Table B-8). The RRW of FR-07a is 1.43 for Fire and yields a benefit based on RRW (with uncertainty) of $675,000 based on Fire alone.

Since there is no impact to Internal Events, the RRW for Other External Events is set equal to the primary hazard benefit. The resulting benefit is $1,350,000 and exceeds the amount calculated by the Phase 2 analysis.

(2)

SAMA candidate CW-07 provides an example of a SAMA that has an impact on more than one hazard. The Phase 2 calculated benefit with uncertainty is $475,184. The RRW values for this SAMA are 1.12, 1.15, 1.00, 1.12, and 1.255 for Internal Events, Fire, Seismic, Other External Events, and LERF, respectively. The corresponding RRW benefit is $1,000,000 with uncertainty. Again, the RRW b'enefit exceeds that of the actual Phase 2 result.

(3)

SAMA candidates AC/DC-01 and AC/DC-23 provide examples of SAMA candidates with low Phase 2 benefits. The Phase 2 benefit of AC/DC-01 with uncertainty is $8,125 and its RRW benefit with uncertainty is $13,500. Similarly, the AC/DC-23 Phase 2 benefit with uncertainty is $173,164 and its RRW benefit is $224,000.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 24 of 173 This method can also be used for screening Criterion D SAMA candidates whose implementation costs do not exceed the total maximum benefit. If sufficient difference between the RRW benefit and the implementation cost exists, the candidate can be screened as excessive cost and not considered for further evaluation since a sufficient basis is available, through the RRW benefit, to conclude that the SAMA candidate would not be cost-beneficial.

In some instances, the implementation cost estimates have been revisited from those provided in Reference 1. The previous estimates for SAMA candidates AT-10, CP-12, CP-22, CP-24, and CC-12 were based on industry estimates.

These estimates were phrased as 'the cost would exceed a specific value'. That value was usually the maximum cost-benefit for that licensee. No approximate estimated cost for the SAMA candidate was provided. With the inclusion of the uncertainty factor based on the 9 5 th percentile sensitivity, the previous entries require a CGS specific estimate to assess the cost-benefit based on maximum uncertainty benefit. The CGS estimates are in accordance with the intent of NEI-05-01. However, the estimates are sufficiently low so that a cost-beneficial SAMA candidate will not be inadvertently screened out. Details of the cost estimates for these SAMA candidates are presented below:

• AT-10 and CP-12 Implementation Cost Estimate Details Cost implementation estimates for SAMA candidates AT-10 and CP-12 are related in that both candidates provide for a filtered containment vent to remove decay heat. This allows the suppression pool to remain effective.

The primary difference in the conceptual design was one of size. SAMA candidate AT-1 0 assumes a filtered containment vent sufficient to accommodate an ATWS event (assumed at 100% power) for a reasonable period of time to allow extra ordinary measures to be implemented to shutdown the reactor.

The design concept for the ATWS-sized cooling vent was that it would require a hardened vent piping from the wetwell to a large tank outside of the reactor building. Since no primary containment penetrations exist of sufficient size, the potential for modifying the wetwell access hatch was conceptualized.

This would replace the existing hatch with one modified for dual purpose (entry and venting). A removal spool piece would be installed between the modified wetwell hatch and the hardened ATWS-sized piping. Pipe routing and supports would be required inside the Reactor Building to avoid the large secondary containment access hatch used for refueling operations and dry cask loading. The piping would exit the secondary containment through secondary containment isolation valves and modifications of the reinforced Reactor Building concrete walls. The piping externally would transition above a Diesel Generator room and to a large pressure-rated tank at ground level.

The tank would have the ability to absorb heat and filter the suppression pool discharge (assuming steam at 220-3000F). A small self-contained diesel generator similar to DG-4 would be available for powering the multiple SGT

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 25 of 173 fans. Drains from the enclosure to Radwaste processing would be provided.

Project management and security impacts were also considered.

The cost for the ATWS-sized filtered containment vent to remove decay heat was estimated as follows:

a. Design - $2,600,000

b. NRC approval - $1,200,000

c. Materials and installation pressure vessel and pad - $2,500,000

d. Modification of wetwell equipment hatch - $1,000,000

e. Large sized piping and solation valves from hatch to Reactor Building penetration: assume 60"- 72" piping - $1,250,000

f. New Reactor Building penetration with inboard/outboard isolation valves -

$1,400,000

g. Piping to ATWS-sized gravel bed enclosure (not estimated)

h. Gravel bed enclosure or vent filters from gravel bed enclosure - $400,000

i. Drain system collection back to Radwaste processing - $850,000

j. Project support - $800,000

k. Security impacts - $750,000 Total: $12,750,000 The design concept for CP-1 2 (Install a filtered containment vent to remove decay heat) was similar except that the pressure vessel size was reduced yielding a $1,000,000 reduction.

Total $11,750,000 CP-22 Implementation Cost Estimate Details SAMA candidate CP-22 proposes to increase the depth of the concrete base mat or to use an alternate concrete material to ensure melt-through does not occur.

The cost estimate for this SAMA candidate assumes thickening the concrete base mat using materials and methods typical of underground tunneling methods standard in underground roadway or underwater rapid transit tunneling projects. The project would be performed in sections or slices in order to avoid massive underground Reactor Building support structures. The cost estimate assumes design, NRC approval, materials, rebar installation, removal of existing below-ground infrastructure conflicts, micro-tunneling, pit excavation, horizontal concrete slurry injection, spoils and re-compaction and miscellaneous project support including security.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 26 of 173 The cost for approximately doubling the Reactor Building base depth was estimated as follows:

a. Design - $5,000,000

b. NRC - $1,500,000

c. 48" micro-tunneling - $12,000,000

d. Pit excavation - $2,500,000

e. Utility/infrastructure conflicts - $6,000,000

f. Rebar material and placement- $2,000,000

g. Horizontal concrete slurry injection - $4,000;000

h. Spoils - $400,000

i. Project Support - $2,500,000 Total: $35,900,000 CP-24 Implementation Cost Estimate Details SAMA candidate CP-24 proposes to construct a building of sufficient size adjacent to the Reactor Building/containment to be maintained at a vacuum in order to provide additional means to filter releases. This SAMA candidate would improve the release mitigation effectiveness of the secondary containment (Reactor Building).

A building sized to the Reactor Building space - 3.5 E+06 cubic feet would be cost-prohibitive. However, a lesser cost option would be to build a large tank which could be maintained at a higher vacuum than the current reactor building at a reduced size. The vacuum could be established and maintained by motor driven vacuum pumps powered by self-contained diesel generators similar to DG-4.

The cost for this SAMA candidate was estimate as follows:

a. Design - $2,250,000

b. NRC approval - $1,500,000

c. Tank - $2,000,000

d. Motor driven vacuum pumps w/building - $1,250,000

e. Diesel w/building - $1,250,000

f. Piping to Reactor Building - $1,000,000

g. Penetration of Reactor Building and isolation valves - $1,000,000

h. Security impacts -$800,000

i. Project support - $800,000 Total: $11,850,000

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 27 of 173 CC-12 Implementation Cost Estimate SAMA candidate CC-1 2 proposes to establish a diverse low pressure system to support injection. CGS design has four existing low pressure systems and one high pressure injection system (HPCS) that can be used for low pressure injection. Initially, this SAMA candidate was screened as low benefit. In response to the NRC RAI to reexamine the Phase 1 screening using an RRW uncertainty benefit method, this candidate was found to have a moderate risk improvement; therefore, it was re-examined. The re-examination found that the RRW uncertainty benefit was approximately $1,000,000. A CGS-specific cost estimate was not developed for this SAMA candidate. The cost estimate developed by Vermont Yankee is used.

For some SAMA candidates that had been screened as Criterion D or Criterion E, no RRW value can be generated by the PSA. SAMA candidates of this nature are those that only affect the release amount and not its frequency. SAMA candidates CP-1 2 and CP-1 3 of Table A-1 5 are of this nature. These SAMA candidates scrub releases to reduce the dose to the public but do not affect the frequency of the release; thus, an RRW is not possible to generate. For these SAMA candidates, a search of the industry Phase 2 SAMA analysis has been performed. The search identified that SAMA candidates CP-12 and CP-13 have been evaluated by other BWRs using a Phase 2 analysis. Their benefit and implementation costs have been reviewed for applicability to CGS. Where appropriate, these references are used to assess the likely benefit and costs at CGS and are used in the Phase 1 screening of the candidates.

Finally, in a few cases, the reevaluation has determined that a revised screening criterion is warranted or that the SAMA candidate has effectively been addressed by an alternate SAMA candidate that was developed during the response to the original set of RAIs. In some cases, application of the uncertainty factor has changed the screening from Criterion E (Very Low Benefit) to one of the other four criteria. In addition, a few SAMA candidates have been determined to either be not applicable to CGS (Criterion A) or to have already been implemented (Criterion B) (or are in the process of being implemented). The screening criteria for the affected SAMA candidates have been revised as appropriate and justification provided.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 28 of 173 The results of the reevaluation of the original Criterion D and Criterion E SAMA candidates using the approaches described above are presented in Tables A-15 and A-16, respectively. No additional SAMA candidates were identified from the reevaluation.

Energy Northwest concludes that the RRW benefit method provides high assurance in discerning the cost-benefit potential of these SAMA candidates.

The use of the RRW uncertainty benefit method requires the first step of a Phase 2 evaluation to be performed (i.e., modeling the SAMA candidate in the PSA) for Criterion E candidates. This method is also useful in supporting the screening of Criterion D candidates whose estimated implementation cost does not exceed the maximum uncertainty benefit. For these cases, an RRW uncertainty benefit can be established and its potential for being cost-beneficial readily determined.

This approach results in a more thorough evaluation of the candidates' importance for risk mitigation. These results support the use of the qualitative Phase 1 screening approach prescribed by NEI 05-01. The use of the RRW uncertainty benefit method is effective as an additional check for those candidates for which some doubt exists as to a candidate's potential benefit without having to perform a full Phase 2 evaluation.

5.0 CONCLUSION

S As shown in Attachment 2, the following SAMA candidates were determined to be cost-beneficial using PSA Rev. 6.2: AC/DC-28, CC-03b, FR-07a, FR-07b, FR-08 and HV-02.

Based upon the results in Table B-8, the following additional SAMA candidates are cost-beneficial: SR-05R, FL-05R, FL-04R, FL-06R, CC-24R, CC-25R, OT-07R, FW-05R, OT-09R and FR-11 R.

All of the above SAMA candidates (16 total) will be considered for implementation through the normal processes for evaluating possible plant changes at CGS as described in Attachment 2 RAI 6.j-1 iv.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 29 of 173 APPENDIX A PSA MODEL REVISION Table A-1 (Internal Events)

Table A-1 (Fire)

Table A-1 (Seismic)

Table A-2 Table A-3.

Table A-4 Table A-5 Table A-6 Table A-7 Table A-8 Table A-9 Table A-10 Table A-11 Table A-12 Table A-13 Table A-14 Table A-15 Table A-16 Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Comparison of LERF Contributions for PSA Models Rev.

6.2 and Rev. 7.1 Internal Events Level 2 Release Categories Fire Level 2 Release Categories Seismic Level 2 Release Categories Base Case Sensitivity Results for Internal Events (release category, whole body dose, economic impact)

Base Case Sensitivity Results for Fire (release category, whole body dose, economic impact)

Base Case Sensitivity Results for Seismic (release category, whole body dose, economic impact)

Level 1 Internal Events Basic Events Importance List Level 2 Internal Events Basic Events Importance List Level 1 Fire Basic Events Importance List Level 2 Fire Basic Events Importance List Level 1 Seismic Basic Events Importance List Level 2 Seismic Basic Events Importance List Re-evaluation of Phase 1 Screening of Criterion D SAMA Candidates Re-evaluation of Phase 1 Screening of Criterion E SAMA Candidates

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 30 of 173 Table A-1 (internal Events): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Total CDF:

Rev 7.1 - 7.4E-06 Rev 6.2 - 4.77E-06 Overall Factor Difference:

1.54 Initiator D

i CDF Percentage CDF Percentage Discussion Factor Description

(/rx-yr) of total CDF

(/rx-yr) of total CDF Difference Several ISLOCA event tree revisions that arose from F&Os resulted in increased CDF ISLOCA for Rev. 7.1:

pipe rupture likelihood now based on published data; if is ISLOCA 1.02E-07 1%

3.8E-1 0 0%

piping doesn't rupture, it 268.5 leaks (no credit for "no leakage"); early isolation probability increased based on updated guidance; initiating event frequency based on most current failure data.

Revised HEPs from the S1 MLOCA 7.83E-08 1%

3.6E-10 0%

updated HRA caused an increase in CDF contribution 219.7 from MLOCA.

Enhanced modeling realism caused the CDF to increase:

TSH6 Loss of Bus SH-6 2.58E-08 0%

3.7E-10 0%

the backup source of cooling 69.9 for CRD operation is impacted by the loss of the 6.9kV bus SH-6.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 31 of 173 Table A-1 (Internal Events): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Total CDF:

Rev 7.1 - 7.4E-06 Rev 6.2 - 4.77E-06 Overall Factor Difference:

1.54 CDF Percentage CDF Percentage Discussion Factor Initiator Description

(/rx-yr) of total CDF

(/rx-yr) of total CDF Difference ATWS contributions increased due to not crediting HPCS, LPCS, and LPCI injection based on insights from plant procedures and TTC2 Turbine Trip ATWS 1.39E-09 0%

5.3E-1 1 0%

Operations to minimize 26.2 Low Power power flow oscillations. This was driven by the EOPs, where HPCS is allowed to be used only under certain restrictive conditions for power level control.

TFC Loss of FW ATWS 5.33E-07 7%

2.2E-08 0.5%

See TTC2.

24.8 TMC MSIV Closure ATWS 2.13E-07 3%

9.1E-09 0%

See TTC2.

23.4 TIC SORV ATWS 1.22E-07 2%

5.7E-09 0%

See TTC2.

21.3 Loss of TSW initiating event frequency increased for Rev.

7.1. The previous initiating event fault tree modeling had deficiencies relative to the TTSW Loss of TSW 1.62E-08 0%

9.5E-1 0 0%

requirements of the ASME/ANS PRA Standard's 16.9 requirements. The new initiating event frequency for the TTW initiator is also now in close agreement with generic initiating event data.

TCC Loss of Condenser 3.39E-07 5%

2.2E-08 0.5%

See TTC2.

15.1 ATWS The initiating event frequency TIA Loss of CIA 8.29E-08 1%

7.2E-09 0%

increased for Rev. 7.1, which 11.5 reflects plant-specific experience.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 32 of 173 Table A-1 (Internal Events): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Total CDF:

Rev 7.1 - 7.4E-06 Rev 6.2 - 4.77E-06 Overall Factor Difference:

1.54 CDF Percentage CDF Percentage Factor Initiator Description

(/rx-yr) of total CDF

(/rx-yr) of total CDF Discussion Difference In accordance with the ASME/ANS PRA Standard, initiating event TM now TM MSiV Closure 3.56E-07 5%

4.6E-08 1%

includes bus losses that cause MSIV Closure, which include a loss of 4160V switchgear E-SM-7 and a loss of 480V bus E-SL-71.

Manual Shutdown now includes explicit modeling of TS LCO related shutdowns MS Manual Shutdown 7.87E-07 11%

1.3E-07 3%

that could arise from failures 6.2 of equipment modeled in the PSA, driven by the ASME/ANS PRA Standard.

Potential CCF plugging of A

LLOCA 6.02E-10 0%

9.7E-11 0%

ECCS suppression pool 6.2 suction strainers is now modeled.

The increase to the SLOCA contribution was primarily S2 SLOCA 2.40E-08 0%

4.OE-09 0%

due to an update of the 6.1 human failure event I_ dependency analysis.

TTC Turbine Trip ATWS 1.43E-07 2%

2.5E-08 0.5%

See TTC2.

5.8 Full Power I

I I

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 33 of 173 Table A-1 (Internal Events): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Total CDF:

Rev 7.1 - 7.4E-06 Rev 6.2 - 4.77E-06 Overall Factor Difference:

1.54 CDF Percentage CDF Percentage Discussion Factor Initiator Description

(/rx-yr) of total CDF

(/rx-yr) of total CDF Difference For Rev. 7.1, LOCA outside containment modeling now includes explicit modeling for all potential sources (MS, RFW, RWCU, RCIC), rather than only MS. LOCAs LOCA LOCA Outside 583E07 8%

1.5E-07 4%

outside containment also now 3.8 Outside Containment account for the environmental Containment impacts to plant equipment as required by the ASME/ANS PRA Standard, e.g., impacts to 4160V buses SM-1, SM-2 and SM-3 in the Turbine Building.

The human reliability dependency analysis was TF Loss of FW 7.19E-07 10%

1.9E-07 4%

updated, which was a 3.8 significant reason for the increased contribution from TF.

Flood sources were identified in the Radwaste / Control Building and are now modeled in the Rev. 7.1 PSA.

Internal This upgrade was driven by Flooding Internal Flooding 2.32E-06 31%

7.4E-07 15%

supporting requirements 3.1 IFSO-A1 and ISFO-A5 to identify flooding sources from fire, service water systems, etc., for a range of break sizes SR Reactor Level 1.42E-07 2%

7.OE-08 1%

Relatively similar contribution 2.0 Instrument Line Break 3.69I-07_5%

2.2E-07 45SilatoT1.

TC Loss of Condenser 3.69E-07 5%

12.2E-07 4.5%

Similar to TF 1.7

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 34 of 173 Table A-1 (Internal Events): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Total CDF:

Rev 7.1 - 7.4E-06 Rev 6.2 - 4.77E-06 Overall Factor Difference:

1.54 CDF Percentage CDF Percentage Discussion Factor Initiator Description

(/rx-yr) of total CDF

(/rx-yr) of total CDF Difference T il22No Significant change in the 1.3 TT Turbine Trip 1.48E-07 2%

1. 1 E-07 2%

CDF result.

CR-HV Loss of Control Room 4.15E-10 0%

4.1E-10 0%

No Significant change 1.0 HVAC TI Inadvertent Open Relief Valve / SORV 8.27E-08 1%

2.1E-07 4%

No Significant change 0.4 The LOOP initiating event T(E)N LOOP 9.25E-08 1%

3.OE-07 6%

frequency was updated to the 0.3 most current data.

TCAS Loss of Control and 2.38E-08 0%

1.OE-07 2%

No significant change 0.2 Service Air SBO-I SBO with RCIC DG-3 crosstie is modeled in 0.1 Available 6.51 E-08 1%

5.3E-07 12%

Rev. 7.1.

Rev. 7.1 produced a significant reduction in the contribution from SBO-R, S130 with RCIC primarily due to a large SBO-R Unavaith 6.01E-08 1%

1.1E-06 23%

reduction in RCIC failure-to-0.1 run data provided by NUREG/CR-6928, and the modeling of the DG-3 cross-ties.

Refined unavailability for EACTRL-ASH E-W3D1 TSH5 Loss of SH-5 1.08E-11 0%

3.2E-10 0%

(unavailability of offsite power 0.0 to TR-S) reduced this CDF contribution significantly.

Excessive LOCA Initiating event frequency RPVR Ecsv e

9.95E-09 0%

3.OE-07 7%

revised downward based on 0.0 (RPV Rupture)

NRC expert elicitation.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 35 of 173 Table A-1 (Internal Events): Comparison CDF Contributions-for PSA Models Rev. 6.2 and Rev. 7.1 Total CDF:

Rev 7.1 - 7.4E-06 Rev 6.2 - 4.77E-06 Overall Factor Difference:

1.54 CDF Percentage CDF Percentage Discussion Factor Initiator Description

(/rx-yr) of total CDF (Irx-yr) of total CDF Difference Refined unavailability for EACTRL-ASHE-W3D1 TSM3 Loss of SM-3 1.08E-1 1 0%

3.5E-10 0%

(unavailability of offsite power 0.0 to TR-S) reduced this CDF contribution significantly.

Refined unavailability for EACTRL-ASHE-W3D1 TSM1 Loss of SM-1 2.72E-10 0%

1.4E-08 0%

(unavailability of offsite power 0.0 to TR-S) reduced this CDF contribution significantly.

Refined unavailability for EACTRL-ASHE-W3D1 TSM2 Loss of SM-2 9.53E-1 0 0%

6.2E-08 1%

(unavailability of offsite power 0.0 to TR-S) reduced this CDF contribution significantly.

Refined unavailability for Loss of Div 2 DC EACTRL-ASHE-W3D1 TDC2 Power 5.50E-1 1 0%

7.1 E-09 0%

(unavailability of offsite power 0.0 to TR-S) reduced this CDF contribution significantly.

Refined unavailability for Loss of Div 1 DC EACTRL-ASHE-W3D1 TDC1 Power 4.70E-1 1 0%

7.8E-09 0%

(unavailability of offsite power 0.0 to TR-S) reduced this CDF contribution significantly.

TEC LOOP /ATWS 4.79E-08 1%

n/a 0%

New initiating event n/a new FLCqL (flood Combined results in Flood Consequential with n/a -

consequential LOOP Internal new lE LOOP)

Flood Loss of Div 1 and Div n/a -

DDC 2 DC Power 8.61 E-09 0%,

new IE 0%

New initiating event n/a Group

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 36 of 173 Table A-1 (Internal Events): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Total CDF:

Rev 7.1 - 7.4E-06 Rev 6.2 - 4.77E-06 Overall Factor Difference:

1.54 CDF Percentage CDF Percentage Discussion Factor Initiator Description

(/rx-yr) of total CDF

(/rx-yr) of total CDF Difference FLSBR(flood followed by Combined consequential Flood SBO following with n/a -

LOOP results Consequential LOOP Internal n/a new IE 0%

New initiating event n/a in SBO with

- RCIC Unavailable RCIC Flood unavailable)

FLSBI (flood followed by Combined consequential Flood SBO following with n/a-LOOP results Consequential LOOP Internal n/a new IE 0%

New initiating event n/a in SBO with

- RCIC Available Flood RCIC available)

Loss of SM-7 and DAC SM-8 Due to CCF 3.32E-09 0%

n/a 0%

New initiating event n/a Loss of Div 1 No longer an initiating event and Div 2 No longer an initiating 0

0%

4.3E-07 9%

based on updated room heat-n/a Switchgear event HVAC up calculations No longer an initiating event SG1HV No longer an initiating 0

0%

1.4E-08 0%

based on updated room heat-n/a event up calculations No longer an initiating event SG2HV No longer an initiating 0

0°/o 1.OE-09 0%

based on updated room heat-n/a eventup calculations

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 37 of 173 Table A-1 (Fire): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.12 Fire Compartment Rev 6.2 Fire Rev. 7.1 Fire Fire CDF Percenta e CDF (/rx-yr)

CDF (/rx-yr)

Difference Increase Discussion Total 3.6E-06 1.37E-05 1.01 E-05 278%

The Rev. 7.1 FPSA modeling of long term RCIC operation differs from the Rev. 6.2 FPSA in crediting RCS makeup in the event RCIC fails to continue to run due to containment back-W07 (Radwaste 467' pressure. The assumption that an RCS W07 Radwste 67'makeup source was available was not carried Division 2 Electrical 9.OE-08 1.7E-06 1.6E-06 44%

frard forRev a.aThe Integrated Equipent)forward for Rev 7.1 FPSA. The Integrated PSA Equipment)

Model Rev. 7.1 was established for SAMA evaluations and this conservatism is judged appropriate for the SAMA application. This resulted in an increased importance for fire compartment W07.

Based on the revised Rev. 7.1 RFW fault tree model, RFW is now failed if a full compartment TIC (Turbine 5.2E-08 1.3E-06 1.3E-06 36%

burnout occurs. Modeling of additional Generator East 441')

dependencies in the Rev 7.1 Internal Events model identified increased importance to this fire compartment.

Rev. 7.1 has a conservatism in modeling the failure of some Division 2 equipment associated with this fire compartment. The investigation into this conservatism was not completed prior W04 (Radwaste 467' to performing the sensitivity study. When this Division 1 Electrical 8.4E-07 1.7E-06 8.6E-07 24%

conservatism is removed, the Rev. 7.1 W04 Equipment Room) compartment fire CDF decreases by a factor of about two. Overall fire CDF decreases by about 6%. This modeling would not adversely affect the SAMA analysis results by screening out a cost-beneficial SAMA candidate.

W08 (Radwaste 467' 3.6E-07 9.7E-07 6.1 E-07 17%

See discussion for compartment W07.

Switchgear Room #2)

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 38 of 173 Table A-1 (Fire): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.12 Fire Compartment Rev 6.2 Fire Rev. 7.1 Fire Fire CDF Percenta e CDF (/rx-yr)

CDF (/rx-yr)

Difference Increase Discussion Total 3.6E-06 1.37E-05 1.01 E-05 278%

The Rev. 6.2 FPSA credits one train of RHR to be available and not failed for a fire in this compartment. This was not carried forward to the Rev. 7.1 integrated model. The investigation to confirm this modeling assumption was not completed prior to W03 (Radwaste 467'-

4.5E-07 9.4E-07 5.OE-07 14%

performing the sensitivity study. When this 525' Cable Chase) conservatism is removed, the Rev. 7.1 W03 compartment fire CDF decreases by a factor of about two. Overall fire CDF decreases by about 3%. This modeling would not adversely affect the SAMA analysis results by screening out a cost-beneficial SAMA candidate.

The Rev. 6.2 FPSA model provided non-repair probabilities to recover fire-induced losses of W14 (Radwaste 467' offsite power. This assumption was removed Switchgear Room #1) 1.0E06 1.4E-06 4.5E-07 12%

for Rev 7.1 integrated FPSA. This resulted in an increase in risk importance in the Rev 7.1 model for this compartment.

R1C (Southeast 2.OE-08 3.9E-07 3.7E-07 10%

Increased CDF in Rev. 7.1 for reasons similar Reactor Building 471')

to compartment R1K.

Wi1A (Radwaste Building 437w 1.2E-07 4.4E-07 3.2E-07 8.8%

See discussion for compartment W07.

W13 (Radwaste 525' 2.OE-07 4.9E-07 2.9E-07 7.9%

See discussion for compartment W07.

Emergency Chiller)__________________________________

R1 L (Reactor Building 3.3E-09 2.4E-07 2.3E-07 6.4%

See discussion for compartment W07.

572')

For one fire scenario modeled for W02, RHR is W02 (Cable Spreading 2.2E-07 4.4E-07 2.2E-07 6.0%

modeled as completely failed due to fire Room) impacts. This is conservative. See the discussion for compartment W03.

TGnA (Turbine 1.6E-07 2.9E-07 1.3E-07 3.6%

See discussion for compartment W07.

Generator West 441')

T1eD (Turbine 4.9E-08 1.6E-07 1.1 E-07 2.9%

See discussion for compartment W07.

Generator West 471')

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 39 of 173 TAble A-1 (Fire): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.12 Fire Compalment Rev 6.2 Fire Rev. 7.1 Fire Fire CDF Percentage CDF (/rx-yr)

CDF (/rx-yr)

Difference Increase Discussion Total.

3.6E-06 1.37E-05 1.01 E-05 278%

T1 H (Turbine 3.5E-09 1.1 E-07 1.OE-07 2.8%

See discussion for compartment W07.

Generator Center 501')

This was a methodology change for Rev. 7.1.

A 0.5 recovery probability was applied in Rev.

6.2 to re-close RHR-V-27A if it spuriously opens R1 B (Northeast 5.8E-08 1.6E-07 1.0E-07 2.8%

due to fire. RG 1.200 requires that analysis be Reactor Building 471')

performed to demonstrate that RHR-V-27A would not be damaged by the hot short by bypass of torque limit switch. The 0.5 credit was removed for Rev. 7.1.

T10 (West Transformer 1.9E-09 8.6E-08 8.4E-08 2.3%

See discussion for compartment TIC.

Vault)

Ti I (Turbine Generator 3.OE-09 8.4E-08 8.1 E-08 2.2%

See discussion for compartment W07.

East 501')

T1GG (Turbine 9.4E-09 8.7E-08 7.7E-08 2.1%

See discussion for compartment W07.

Generator West 501')

W05 (Radwaste 467' A human failure event for aligning SW as an Battery Room 1) 2.5E-07 3.2E-07 6.4E-08 1.8%

alternate injection source was added to the modeling in Rev. 7.1.

A model linking problem in Rev 6.2 was Ri K 2.OE-08 6.9E-08 4.9E-08 1.4%

corrected and incorporated into Rev 7.1. This produced a small increase in the compartment risk importance.

S01 2.6E-09 4.6E-08 4.3E-08 1.2%

See discussion for compartment W07.

RME 6.5E-10 4.1E-08 4.OE-08 1.1%

See discussion for compartment RIK.

Computed for each compartment by dividing CDF Difference for each compartment by the total Rev. 6.2 Fire CDF.

2 This table compares CDF for all fire compartments whose Rev. 7.1 CDF increased by at least 1% from the Rev. 6.2 Fire compartment CDF.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 40 of 173 Table A-1 (Seismic): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Seismic Description of Seismic Rev. 7.1 Rev. 6.2 CDF Percentage Damage ImpacDs DaaeImpacts CFD Difference Difference Discussion State

(/rx-year)

(/rx-year)

Total 4.9E-06 5.3E-06

-3.9E-07

-7.4%

In Rev. 7.1 Internal Events RCIC suction from the suppression pool is not credited due to operational preference in BOP, CST, LOOP, N2 Tank, procedures to use the CST. For this SDS38 DOs STa and No Tarte 9.5E-08 5.8E-08 3.7E-08 63.8%

seismic damage state, the CST is DGs stalled and not re-started unavailable; therefore RCIC is modeled as unavailable, which produces a reasonably conservative net higher CDF for Rev. 7.1.

S2P3 (1)

BOP, CST, LOOP, small-small 68E08 34E08 33E08 97.1%

CDF increased for reasons similar to LOCA 68-8 340 seismic damage SDS38.

SDS2 BOP, CST, LOOP, small-small 4.8E-08 2.OE-08 2.8E-08 140.0%

CDF increased for reasons similar to LOCA

__seismic damage SDS38.

BOP, CST, LOOP, N2 Tank, CDF increased for reasons similar to S523 small-small LOCA, DG 1 &2, 1.4E-07 1.3E-07 1.1 E-08 8.5%

seismic damage SDS38.

Div. III BOP, CST, LOOP, N2 Tank, CDF increased for reasons similar to 1129 SLOCA,1.8E-08 1.6E-08 1.3E-09 8.1%

seismic damage SDS38.

SDS20 (3)

BOP, CST, LOOP, N2 Tank, 1

3E CDF increased for reasons similar to small-small LOCA 1

3 seismic damage SDS38.

S20P3 (3) BOP, CST, LOOP, N2 Tank, 1.2E-09 5.8E-10 5.8E-10 100.0%

CDF increased for reasons similar to small-small LOCA 12-9 581 seismic damage SDS38.

SDS3 (2) BOP, CST, LOOP, small-small 9.3E-10 8.1E-10 1.2E-10 14.8%

seCDF increasedfor reasons similar to LOCA, Div. Ill seismic_

damage_____

SDS8 BOP, CST, LOOP, SLOCA 1.4E-10 3.4E-11 1.OE-10 294.1%

CDF increased for reasons similar to seismic damage SDS38.

SDS21 BOP, CST, LOOP, N2 Tank, 2.7E-10 2.3E-10 4.OE-11 17.4%

CDF increased for reasons similar to small-small LOCA, Div. III seismic damage SDS38.

BOP, CST, LOOP, N2 Tank, CDF increased for reasons similar to S1331 SLOCA, Div. I&II, Div. III, 1.6E-08 1.6E-08 3.OE-11 0.2%

seismic damage SDS38.

Offsite AC Not Recoverable seismicdamage__DS38.

BOP, CST, LOOP, N2 Tank, 2.3E-11 5.3E-12 1.8E-11 339.6%

CDF increased for reasons similar to SDS26 SLOCA seismic damage SDS38.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 41 of 173 Table A-1 (Seismic): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Seismic Description of Seismic Rev. 7.1 Rev. 6.2 CDF Percentage Damage Impacts CDF CDF Difference Difference Discussion State

(/rx-year)

(/rx-year)

Total 4.9E-06 5.3E-06

-3.9E-07

-7.4%

SDS42 Failure of RPV and/or Category 2.4E-06 2.4E-06 0.0E+00 0.0%

No Change I Buildings SDS41 Wide-spread failure of SSEL 1.6E-06 1.6E-06 0.OE+00 0.0%

No Change equipment BOP, CST, LOOP, N2 Tank, SLAC MLOCA, Div. I&II, Div. Ill, 1.1 E-07 1.1 E-07 0.OE+00 0.0%

No Change Offsite AC Not Recoverable BOP, CST, LOOP, N2 Tank, S725 small-small LOCA, Div. I&lI, 1.OE-07 1.0E-07 0.OE+00 0.0%

No Change Div. III, Offsite AC Not Recoverable SDS40 Seismic Failure to Scram and 7.9E-09 7.9E-09 0.OE+00 0.0%

No Change Failure to Mitigate CCF probabilities were updated for Rev.

7.1 Internal Events. There was a S2P2 (1)

BOP, CST, LOOP, small-small 0.0E+00 1.8E-07

-1.8E-07

-100.0%

reduction in the CCF probabilities for the LOCA DGs as a result of this update, a net reduction in CDF for this seismic damage state occurred.

For Rev. 7.1, the likelihood for failure of BOP, CST, LOOP, N2 Tank, HPCS injection given containment failure S624 small-small LOCA, Div. I&lI, 9.OE-08 2.2E-07

-1.3E-07

-59.1%

was refined to remove conservatism.

Offsite AC Not Recoverable This produced a net reduction in the CDF for this seismic damage state.

SDS4 BOP, CST, LOOP, small-small 8.2E-08 1.8E-07

-1.0E-07

-55.6%

CDF decreased for reasons similar to LOCA, DG 1 &2 seismic damage S624.

SDS22 BOP, CST, LOOP, N2 Tank, 2.8E-08 6.2E-08

-3.4E-08

-54.8%

CDF decreased for reasons similar to small-small LOCA, DG 1&2 seismic damage S624.

BOP, CST, LOOP, N2 Tank, CDF decreased for reasons similar to S1836 MLOCA, Div. 1&ll, Offsite AC 8.1E-09 2.OE-08

-1.2E-08

-60.0%

seismic damage S624.

Not Recoverable BOP, CST, LOOP, N2 Tank, CDF decreased for reasons similar to S1230 SLOCA, Div. I&Il, Offsite AC 7.4E-09 1.8E-08

-1.OE-08

-55.6%

seismic damage S624.

Not Recoverable I

III

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 42 of 173 Table A-1 (Seismic): Comparison CDF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Seismic Description of Seismic Rev. 7.1 Rev. 6.2 CDF Percentage Discussion Damage Impacts (xa (Dfe Denis i

State

(/rx-year)Difference Difference Total 4.9E-06 5.3E-06

-3.9E-07

-7.4%

BOP, CST, LOOP, MLOCA, DG CDF decreased for reasons similar to SDS16 1&2 3.9E-09 8.9E-09

-5.OE-09

-56.2%

seismic damage S624.

BOP, CST, LOOP, SLOCA, DG 3.7E-09 8.1E-09

-4.4E-09

-54.3%

CDF decreased for reasons similar to SDSlO 1&2 seismic damage S624.

S20P2 (3)

BOP, CST, LOOP, N2 Tank, AE-09

-44E0 1

CDF decreased for reasons similar to small-small LOCA 0.0E+00 4.4E-0 seismic damage S2P2.

SDS34 BOP, CST, LOOP, N2 Tank, 2.8E-09 6.3E-09

-3.6E-09

-57.1%

ODE decreased for reasons similar to SMLOCA, DG 1&2 seismic damage S624.

BOP, CST, LOOP, N2 Tank, 2.7E-09 6.OE-09

-3.3E-09

-55.0%

CDF decreased for reasons similar to SDS28 SLOCA, DG 12&2 seismic damage S624.

(2)

ODE decreased for reasons similar to S3P2 ()BOP, OST, LOOP, small-small 3.7E-09 4.6E-09

-8.3E-1 0

-18.0%

seimi damraged foeson2P2iart

_____LOOA, Div. IllsimcdaaeS12 S8P2 (4)

BOP, CST, LOOP, SLOCA 1.3E-10 7.2E-10

-5.9E-10

-81.9%

ODE decreased for reasonssimilarto seismic damage S2P2.

S21 P2 (4) BOP, CST, LOOP, N2 Tank, 1.1E-09 1.4E-09

-2.6E-10

-18.6%

CDF decreased for reasons similar to small-small LOCA, Div. III seismic damage l2P2.

SDS14(4)

BOP, CST, LOOP, MLOCA 2.9E-11 2.4E-10

-2.1 E-10

-87.5%

ODE decreased for reasons similar to seismic damage S2P2.

SDS15 (4)

BOP, CST, LOOP, MLOCA, 1.5E-10 34E-10

-1.9E-10

-55.9%

CDF decreased for reasons similar to Div. III seismic damage S2P2.

S26P2 (4)

BOP, CST, LOOP, N2 Tank, 1.OE-11 1.7E-10

-1.6E-1,0

-94.1%

CDF decreased for reasons similar to SLOCA seismic damage S2P2.

SDS33 (4) BOP, CST, LOOP, N2 Tank, 1.OE-10 2.2E-10

-1.2E-10

-54.5%

CDF decreased for reasons similar to MLOCA, Div. III seismic damage $2P2.

SDS32 (4)

BOP, CST, LOOP, N2 Tank, 6OE-12 6.8E-11

-6.1E-11

-89.7%

CDF decreased for reasons similar to MLOCA seismic damage S2P2.

CDF decreased for reasons similar to SDS27 (4) BOP, CST, LOOP, N2 Tank, 6.1E-11 1.1E-10

-5.2E-11

-47.3%

seismic damage S2P2.

SLOCA, Div. III SDS9 (4)

BOP, CST, LOOP, SLOCA, Div.

1.2E-10 1.6E-10

-4.2E-1 1

-26.3%

ODE decreased for reasons similar to Il seismic damage S2P2.

,OnDn C000 A on'0 i

r-l

.A+

k in T*h IC

-/*

Tha InAtrn ocnaraotor trf olrmAi rfirart em nrnfiln hotwoAon ralicinncl (2)

(3)

SDS3 and wee r

t r

in Te cvia s

V V

SDS3 and $3P2 were reported together in Table E.3-10. They were separated to allow direct comparison between revisions.

SDS20, S20P2, and S20P3 were reported together in Table E.3-10. They were separated to allow direct comparison between revisions

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 43 of 173 (4) These damage states were below the level of detail provided in Table E.3-10

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 44 of 173 Table A-2: Comparison of LERF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Rev. 6.2 Point F-V B eve Nam Basic Event Description Est IPR RAW RRW Comparison to Rev. 7.1 Basic Event Name Est.

IMPORT The frequency for Class 5A in Rev. 7.1 reduced to 1.3E-07/rx-year. Although the ISLOCA contribution to Class 5A increased for Rev. 7.1, the contribution to IE-V CLASS V SEQUENCE 1.52E-07 2.33E-01 1531424.63 1.303 Class 5A from MS LOCAs outside containment reduced due to modeling refinements, producing a net frequency reduction of approximately 13 percent for Class 5A and also a reduction in LERF.

In Rev. 6.2 all internal flooding accident sequences were assigned to the large early release accident class, which is IE-IC CLASS IC 1.52E-07 2.33E-01 1531424.63 1.303 conservative. Realistic PDSs were assigned for internal flooding accident sequences in Rev. 7.1, which produced a reduction in LERF.

Rev. 7.1 modeling refinements reduced STEAM EXPLOSION the likelihood for the occurrence of an ex-STMEXP-OTHER OCCURS IN PEDESTAL 7.OOE-01 1.93E-01 1.08 1.239 vessel steam explosion that fails AT VESSEL FAILURE containment, which produced a reduction in LERF.

The frequency for Class IVBA ATWS EVENTS WITH approximately doubled in Rev. 7.1 to 2.3E-07. The increased contribution to IE-IVBA VESSEL INITIALLY 1.13E-07 1.73E-01 1531424.75 1.209 LER7 Thi in goCas s

cVbA INTACT LERF from this doubling of Class 1VBA in Rev. 7.1 is offset by other Rev. 7.1.

LERF modeling refinements.

The frequency for Class 1A2 approximately doubled in Rev. 7.1 to 1.6E-06. The increased contribution to IE-IA2 CALSS IA-2 SEQUENCE 8.43E-07 1.39E-01 165008.84 1.162 LERF fro i

s d b ngo Cau Ain LERF from this doubling of Class 1A2 in Rev. 7.1 is offset by other Rev. 7.1.

LERF modeling refinements.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 45 of 173 Table A-2: Comparison of LERF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Rev. 6.2 Point F-V B eve Nam Basic Event Description Est IPR RAW RRW Comparison to Rev. 7.1 Basic Event Name Est.

IMPORT OPERATORS FAIL TO Rev. 6.2 conservatively assumes a 0.1 LRESPOND IN TIME TO likelihood for failure to depressurize prior ADSHUMNSTARTH3LLINITIATE ADS PRIOR 1.OOE-01 1.36E-01 2.23 1.158 to vessel failure. Modeling for failure to TO VESSEL FAILURE depressurize prior to vessel failure was refined for Rev. 7.1.

The frequency for PDS 6A1 (core CLASS VI-A-1 DURING damage short term during SBO)

IE-VIA1 SHORT TERM SBO 1.03E-06 1.08E-01 105058.65 1.121 decreased from 1.OE-06/rx-year in Rev.

6.2 to 6.1 E-08/rx-year in Rev. 7.1, which reduces the Rev. 7.1 LERF.

The frequency for Class 4BL ATWS EVENTS WITH approximately doubled in Rev. 7.1 to 1.7E-07. The increased contribution to IE-IVBL VESSEL INITIALLY 6.38E-08 9.77E-02 1531424.88 1.108 LERF Thi ing ofCasbtin BREACHED LERF from this doubling of Class 4BL in Rev. 7.1 is offset by other Rev. 7.1.

LERF modeling refinements.

The Rev. 6.2 Level 2 PSA distinguished between HPCS mechanical and electrical HPCS FAILURE DUE TO failures because recovery of HPCS HPCS-FAIL-6A1-M MECHANICAL7.1E-01 7.68E-02 1.03 1.083 electrical failure was credited. The Rev.

7.1 Level 2 PSA does not credit recovery of HPCS, so this basic event is no longer modeled.

Likelihood for depressurization system DEPRESSURIZATION mechanical failure given core damage DEPSYS-FAIL SYSTEM HARDWARE 5.OOE-02 6.82E-02 2.3 1.073 was refined from 5E-02 in Rev. 6.2 to FAILURE ON DEMAND approximately 1.1 E-03 in Rev. 7.1, which decreased the Rev. 7.1 LERF.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 46 of 173 Table A-2: Comparison of LERF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Rev. 6.2 Point F-V B eve Nam Basic Event Description Est IPR RAW RRW Comparison to Rev. 7.1 Basic Event Name Est.

IMPORT The CGS Rev. 7.1 Level 2 PSA models a similar failure mode with basic event L2-PHE-TDZ-MAP-- "OP=F; Excess Debris Discharged to Outer DW". Basic event L2-PHE-TDZ-MAP-- is modeled with a probability of 0.1 in the Level 2 TD node "Injection Established to RPV or Drywell SHELL FAILURE DUE For Ex-Vessel Debris Cooling". The SHELL ----

FAIL TO HIGH PRESSURE 4.00E-01 6.04E-02 1.09 1.064 probability of 0.4 used in the Rev. 6.2 HLELHANIGH L

PRSURE Emodel is judged to be conservative because it is based on information in NUREG-1 150 for Mark I drywell liner failure probability. The CGS Mark II containment and pedestal configuration is sufficiently different than the Mark I containment referenced in NUREG-1 150 to justify a lower probability in the CGS Rev. 7.1 Level 2,PSA model.

The CGS Rev. 7.1 Level 2 PSA credits alignment of the SW-B crosstie to RHR B for alternate RPV injection. Given failure to align the SW-B crosstie to RHR B prior.

FAILURE TO REALIGN to core damage, the conditional HEP for LPSHUMNRESTORE AND START LOW 1.OOE-01 5.73E-02 1.52 1.061 failure to perform this operator action PRESSURE SYSTEMS prior to containment failure is 1.6E-02.

The HEP is based on plant specific procedures for performing all crosstie actions within the main Control Room and plant specific MAAP runs to support the sequence timing.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 47 of 173 Table A-2: Comparison of LERF Contributions for PSA Models Rev. 6.2 and Rev. 7.1 Rev. 6.2 Point F-V B eve Nam Basic Event Description Est IPR RAW RRW Comparison to Rev. 7.1 Basic Event Name Est.

IMPORT The Rev. 6.2 Level 2 PSA distinguished between HPCS mechanical and electrical HPCS FAILURE DUE TO failures because recovery of HPCS HPCS-FAIL-6A1-E C2.90E-01 3.14E-02 1.08 1.032 electrical failure was credited. The Rev.

ELECTRICAL FAULT 7.1 Level 2 PSA does not credit recovery of HPCS, so this basic event is no longer modeled.

In the CGS Rev. 7.1 Level 2 PSA, short term SBO scenarios credit basic event L2-PHE-AC-RX-OPF "Failure to Recover AC Prior to Vessel Failure - Early CD NO POWER RECOVERY Sequence". Given failure to recover NPWRVF-6A1 PRIOR TO VESSEL 2.1OE-01 2.25E-02 1.08 1.023 offsite AC power prior to core damage, FAILURE - 3HR basic event L2-PHE-AC-RX-OPF is modeled with a conditional probability of 0.41 to represent the approximate 40 minutes available for additional offsite AC power recovery prior to vessel failure.

The frequency for Class 1Al approximately tripled in Rev. 7.1 to 1.7E-IE-IA1 CLASS 1A1 5.08E708 8.38E-03 165004.97 1.008 07/rx-year. The increase in the frequency for Class 1Al in Rev. 7.1 is offset by other Rev. 7.1. LERF modeling refinements.

In Rev. 7.1, the frequency for class 1A3 IE-IA3 CLASS I-A-3 1.45E-07 6.96E-03 47979.66 1.007 is smaller, 5.4E-08/rx-year, which decreased the Rev. 7.1 LERF.

The Rev. 6.2 Level 2 PSA distinguished between HPCS mechanical and electrical failures because recovery of HPCS HPCS FAILURE DUE TO electrical failure was credited. The Rev.

MECHANICAL FAULT 7.1 Level 2 PSA does not credit recovery of HPCS, so this basic event is no longer modeled.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 48 of 173 Table A-3: Internal Events Level 2 Release Categories Release Frequency Category Description (per year)

OK Containment Intact 0

0.0%

H/E High/Early (LERF-BOC) 3.66E-07 4.9%

H/I High/Intermediate 2.35E-07 3.1%

M/E Moderate/Early 2.19E-07 2.9%

M/I Moderate/Intermediate 4.07E-06 54.5%

L/E Low/Early 2.30E-08 0.3%

L/I Low/Intermediate 3.86E-09 0.1%

LL/E Low Low/Early 1.64E-07 2.2%

LL/I Low Low/Intermediate 5.33E-07 7.1%

Table A-4: Fire Level 2 Release Categories Release Frequency Category Description (per year)

Percentage OK Containment Intact 0

0.0%

H/E High/Early (LERF-BOC) 4.35E-08 1 0.3%

H/I High/Intermediate 7.93E-08 0.6%

M/E Moderate/Early 1.77E-08 0.1%

M/I Moderate/Intermediate 8.55E-06 62.3%

L/E Low/Early 2.33E-08 0.2%

L/I Low/Intermediate 8.49E-09 0.1%

LL/E Low Low/Early 8.61 E-07 6.3%

LL/I Low Low/Intermediate 6.13E-07 4.5%

The H/E release decreased from 2.46 E-07 in Rev. 6.2 (LEN) to 4.35 E-08 in Rev. 7.1 for the FPSA.

The decreases for the Internal Events and Seismic hazards were of approximately the same amount but a lower percentage change primarily since the Fire Level 2 H/E frequency is dominated by Loss of RPV makeup scenarios. For the Rev 7.1 Level 2 PSA, the likelihood for Loss of RPV makeup scenarios leading to the H/E end state is much smaller than compared to the Rev 6.2 model. For example, the Rev. 7.1 Level 2 MAAP runs show that Loss of RPV makeup scenarios generally result in delayed containment failure (i.e., non-early release). For the Rev 7.1 Level 2 model, the dominant contributors to the H/E end state for Loss of RPV makeup scenarios involve failures such as Containment Isolation failure, Hydrogen Deflagration, or other phenomenological events which are low probability events.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 49 of 173 Table A-5: Seismic Level 2 Release Categories Release Description Frequency Percentage Category Description (per year)

OK Containment Intact 0

0.0%

H/E High/Early (LERF-BOC) 1.87E-06 38.5%

H/I High/Intermediate 6.09E-07 12.5%

M/E Moderate/Early 4.46E-09 0.1%

M/I Moderate/Intermediate 1.12E-06 23.0%

L/E Low/Early 4.9E-09 0.1%

LI Low/Intermediate 7.17E-10 0.0%

LL/E Low Low/Early 1.29E-07 2.7%

LL/I Low Low/Intermediate 5.75E-07 11.8%

Table A-6: Base Case Sensitivity Results for Internal Events Release Whole Body Dose Economic Impact Category (50 miles, person-rem/yr)

(50 miles, $/yr)

OK 1.50E-03 6.66E-02 H/E 7.36E-01 1.05E+03 H/I 3.41 E-01 6.18E+02 M/E 2.06E-01 2.09E+02 M/I 4.03E+00 5.09E+03 LIE 3.13E-02 4.42E+01 LI 3.82E-03 4.83E+00 LLIE 1.87E-02 1.57E+00 LLII 1.24E-01 5.97E+01 TOTAL 5.49E+00 7.08E+03 Table A-7: Base Case Sensitivity Results for Fire Release Whole Body Dose Economic Impact Category (50 miles, person-rem/yr)

(50 miles, $/yr)

OK 2.79E-03 1.24E-01 H/E 8.74E-02 1.25E+02 H/I 1.15E-01 2.09E+02 M/E 1.67E-02 1.69E+01 M/I 8.46E+00 1.07E+04 LIE 3.17E-02 4.47E+01 LI 8.40E-03 1.06E+01 LLIE 9.82E-02 8.26E+00 LLII 1.42E-01 6.87E+01 TOTAL 8.96E+00 1.12E+04

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 50 of 173 Table A-8: Base Case Sensitivity Results for Seismic Release Whole Body Dose Economic Impact Category (50 miles, person-rem/yr)

(50 miles, $/yr)

OK 4.35E-04 1.93E-02 H/E 3.76E+00 5.37E+03 H/I 8.83E-01 1.60E+03 M/E 4.20E-03 4.26E+00 M/I 1.11 E+00 1.40E+03 LIE 6.66E-03 9.41 E+00 L/

7.09E-04 8.96E-01 LL/E 1.47E-02 1.24E+00 LILI 1.33E-01 6.44E+01 TOTAL 5.91 E+00 8.45E+03

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 51 of 173 Table A-9: Level 1 Internal Events Basic Events Importance List Event Label Description RRW Point Resolution

_______________________Estimate Rslto CGS has an aggressive CRDM replacement/ rebuild program (25-29 per outage). This replaces all drives within approximately 14 years (185 total drives). A rebuilt CRDM costs on average $100K. The SAMA would be associated with increasing the maintenance to improve the reliability. Doubling the replacement CM Mechanical failure of scram 1.249 2.15E-06 program frequency to 53 per outage would result in a system cost of 92.5*$100K = $9.2M over 7 years or $1.3M per year. The RRW importance measure of 1.246 corresponds to an estimated maximum benefit of

$1 00K. Therefore, this is not cost effective. SAMA candidate AT-09 to provide alternate rod insertion is already implemented at CGS. No additional SAMA candidates are required.

HPCS is currently highly reliable. Improvement beyond this is counter-productive to total unavailability. The ability to perform on-line maintenance in a timely HPCSunavilailit du to estmanner (not just in refueling outages) is necessary to HPS -------

T3LL Panto fnailse to ret teHstao 1.208 1.36E-02 maintain high reliability. SAMA candidates CC-01 and

&Cmainten d

urn daan)A S

1.171CC-02, which provide additional high pressure injection capability, increase high pressure injection availability.

These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training, including this Opertor ailsto rstar HPC oroperator action, and SAMA candidate AT-1511 ATWH-HPLPRSTH3XX OperatoIdrfing torsart HPCS or1.171 1.00E+00 evaluates a plant modification that would improve the LPCSLPCIdurig anATWSsuccess of this operator action. These candidates are evaluated for cost-benef it. No additional SAMA candidates are required.

SENSITIVITY STUDY Page 52 of 173 BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Table A-9: Level 1 Internal Events Basic Events Importance List Event Label Description RRW Etimt Resolution SAMA candidate OT-07R evaluates improving procedures and operator training on systems and RHRH-ATWSDC-H3XX Operator.fails to bypass RHR 1.162 8.13E-01 actions shown to be important by the PSA. This basic SDC interlocks during ATWS event is included in SAMA OT-07R. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates CC-01 and CC-02, which provide additional high pressure injection capability, increase HPCS failure due to containment high pressure injection availability. SAMA candidate CF-FAILS-INJECT failure 1.149 8.30E-02 CP-01, which provides additional SPC capability, reduces containment failure probability. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates FW-01 and FW-04, which provide FW upgrades, reduce Loss of FW frequency. FW-01 is already implemented at CGS. FW-04 is evaluated for TF Loss of FW initiating event 1.121 2.OOE-01 cost-benefit. SAMA candidate FW-05R, provide frequency manual control of RFW on loss of DC, reduces Loss of FW frequency. This candidate is also evaluated for cost-benefit. No additional SAMA candidates are required.

This basic event represents the percent of time Standby SW is in operation. Procedures are in place to SW-OPER Standby SW percent operating 1.118 1.12E-01 minimize SW operation, and the SRV leakage time reduction program has been effective at reducing SPC requirements. Significant improvement beyond this is not considered feasible. Not a SAMA candidate.

Any improvement in main condenser reliability will Loss of Condenser initiating require a major hardware modification. This RRW is event frequency well below the $100K minimum value for a hardware I_

I modification. Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 53 of 173 Table A-9: Level 1 Internal Events Basic Events Importance List Point Event Label Description RRW Estimate Resolution SAMA candidates AC/DC-28 and AC/DC-29, which provide DG-3 CCF reduction, improve HPCS power EACENG-EDG3-S424 DG-3 failure to run for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 1.063 3.95E-02 reliability. SAMA candidate CC-24R, which provides DG-3 backfeed, improves HPCS power reliability.

These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

Current unavailability of TR-S overall is 1.46 E-03/year.

Improvement beyond this is counter-productive to total unavailability. The ability to perform on-line Startup transformer E-TR-S maintenance in a timely manner (not just in refueling EACTRL-S ---

S T3--

unavailability due to test &

1.049 1.46E-03 outages) is necessary to maintain high reliability.

maintenancbii e tte data)

SAMA candidates AC/DC-1 4 and AC/DC-27, which provide additional off-site power options, increase power availability. AC/DC-14 is evaluated in Table A-

15. AC/DC-27 is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates FL-05R and FL-04R, which provide Operator fails to isolate major flooding detection and isolation, reduce the probability TSWHUMNIC525H3LL TSW leak in Radwaste Building 1.047 1.OOE+00 of operator failure. These candidates are evaluated for Elevation 525 cost-benefit. No additional SAMA candidates are required.

RHR Train B has high reliability and is green on the MSPI. Further improvement in reliability will require hardware changes or an additional shutdown heat removal system. An example is adding a heat exchanger to RHR Train C with interconnecting piping RHR Train B unavailability due similar to RHR Train A and B and a connection to SW RHR ---- B ---- T3LL to test & maintenance (MRule 1.045 7.96E-03 Train B. Since the benefit from the RRW value is well data) below $100K, this basic event will not be considered further. SAMA candidate CP-01, which provides an additional SPC system, increases low pressure injection availability. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 54 of 173 Table A-9: Level 1 Internal Events Basic Events Importance List

/

Event Label Description RRW Point Resolution Estimate Rslto SAMA candidate FL-06R, which provides additional TModerate or major TSW line NDE and inspections, detects line degradation and bE-FLD-C502TSW-U break in Room C502 1.042 2.52E-06 reduces the flooding frequency. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates FL-05R and FL-04R, which provide Operator fails to isolate flooding detection and isolation, reduce the probability TSWHUMNIC502H3LL moderate or major TSW leak in 1.042 1.00E+00 of operator failure. These candidates are evaluated for Room C502 cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA results. Although this basic event was not included in HPS-CTL-COND----

Operator fails to control RPV 1.041 5.00E-02 SAMA candidate OT-07R, this SAMA candidate proved level using HPCS to be cost effective. This operator action has been identified for increased training. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

Any improvement in HPCS-V-12 reliability will require a HPSV-MO--- 122LL HPCS minimum flow valve 1.04 2.43E-03 hardware modification. This RRW is well below the HPCS-V-12 fails to open

$100K minimum value for a hardware modification. Not a SAMA candidate.

Any improvement in HPCS-V-4 reliability will require a HPSV-MO----4P2LL HPCS injection valve HPCS-V-4 1.04 2.43E-03 hardware modification. This RRW is well below the fails to open

$100K minimum value for a hardware modification. Not a SAMA candidate.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and Operator fails to initiate actions shown to be important by the PSA. This basic ADSHUMNSTARTH3LT depressurization during a non-1.039 1.47E-04 entis include in SM t-e7R

. This c

atis ATWS ventevent is included in SAMA OT-07R. This candidate is ATWS event evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 55 of 173 Table A-9: Level 1 Internal Events Basic Events Importance List Event Label Description RRW Point Resolution Estimate Rslto SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA RHRHUMNSYS62H3LL Operator fails to align SPC prior 1.038 1.63E-04 results. Although this basic event was not included in to loss of RCIC SAMA case OT-07R, this SAMA candidate proved to be cost effective. This operator action has been identified for increased training. No additional SAMA candidates are required.

Any improvement in the frequency of LOOP will require a major hardware modification. This RRW is well below the $100K minimum value for a hardware TE LOOP Initiating Event Frequency 1.036 2.98E-02 modification. SAMA candidate AC/DC-14, which provides an additional off-site power source, reduces LOOP frequency. AC/DC-14 is evaluated in Table A-

15. No additional SAMA candidates are required.

Any improvement in turbine trip frequency will require a Turbine Trip initiating event 1.036 7.10E-01 major hardware modification. This RRW is below the frequency

$100K minimum value for a hardware modification. Not a SAMA candidate.

SAMA candidate OT-07R evaluates improving Operator fails to properly line-up procedures and operator training on systems and 1.032tor fails tactions shown to be important by the PSA. This basic CIAHUMNX-TIEH3XX CAS cross-tie manual valves 1.032event was included in SAMA OT-07R. This candidate when required is evaluated for cost-benefit. No additional SAMA candidates are required.

Any improvement in E-SM-7 reliability will require a EACSM--7 ---- W4D1 Failure of 4160 Volt bus E-SM-7 1.031 1.67E-06 major hardware modification. This RRW is well below the $100K minimum value for a hardware modification.

Not a SAMA candidate.

Any improvement in DMA Damper 31 temperature a

31 sensor reliability will require a hardware modification DMATE -----

31W2LL Failure of DMA Damper 1.03 1.85E-03 such as installation of a redundant temperature sensor.

temperature sensor This RRW is well below the $100K minimum value for a hardware modification. Not a SAMA candidate

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 56 of 173 Table A-9: Level 1 Internal Events Basic Events Importance List Event Label Description RRW Point Resolution Estimate Rslto Any improvement in DMA Damper 32 temperature LFailure of DMA Damper 32 sensor reliability will require a hardware modification DMATE -----

32W2LL temperaiure ofsD r

321.03 1.85E-03 such as installation of a redundant temperature sensor.

temperature sensor This RRW is well below the $100K minimum value for a hardware modification. Not a SAMA candidate Any improvement in E-TR-7/73 reliability will require a hardware modification. This RRW is well below the E A C T R --7 -7 3 -W 4 D 1 F a ilu re o f tra n s fo rm e r E -T R -7 /7 3 1.0 2 9 2.1 7 E -0 5 h a rd w a m ini m u mf v a uei for ah h ar d w are m o dific atio n.t N o

$100K minimum value for a hardware modification. Not a SAMA candidate.

Operator fails to isolate small SAMA candidates FL-05R and FL-04R, which provide SW leak in WMA-AH-52A/B that flooding detection and isolation, reduce the probability SW-HUMN-W521H3LL propagates to the Remote 1.028 5.50E-01 of operator failure. These candidates are evaluated for prutoph R

eom oe cost-benefit. No additional SAMA candidates are Shutdown Room required.

Operator fails to isolate small SAMA candidates FL-05R and FL-04R, which provide SW leak in WMA-AH-52A/B that flooding detection and isolation, reduce the probability XDPHUMN-W521H3LL propagates to the Division 1 1.028 3.20E-01 of operator failure. These candidates are evaluated for propagates tom thcost-benefit.

No additional SAMA candidates are Switchgear Room required.

RHR Train A has high reliability and is green on the MSPI. Further improvement in reliability will require hardware changes or an additional shutdown heat removal system. An example is adding a heat exchanger to LPCS with interconnecting piping similar RHR Train A unavailability due to RHR Train A and B and a connection to SW Train A.

RHR ---- A ---- T3LL to test & maintenance (MRule 1.026 7.94E-03 Since the benefit from the RRW value is well below data)

$1 00K, this basic event will not be considered further.

SAMA candidate CP-01, which provides an additional SPC system, increases low pressure injection availability. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

Any improvement will require a hardware modification such as replacing a MOC switch with a diverse EAC-RHR-CCF CCF of MOC switch assembly 1.024 4.OOE-05 component. This RRW is well below the $1 00K minimum value for a hardware modification. Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 57 of 173 Table A-9: Level 1 Internal Events Basic Events Importance List Event Label Description RRW Point Resolution Estimate Rslto Any improvement in SRV reseat reliability will require a hardware modification. This RRW is well below the Probability of SORV in the 1.025 4.90E-01

$100K minimum value for a hardware modification.

period from 12 to 24 hrs SAMA candidate AT-08, which increases SRV reseat reliability, has been implemented at CGS. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 58 of 173 Table A-10:

Level 2 Internal Events Basic Events Importance List Point Event Label Description RRW1 Estimate Comment/Resolution Used to meet modeling purpose (always 1.0). SAMA NReactor Building ineffective in candidate CP-13 was simulated by reducing the basic L2-PHE-RBINEFF-F reducing source -term 7.551 1.00E+00 event to address the effects of scrubbing releases. CP-13 is evaluated in Table A-15. No additional SAMA candidates are required.

CGS has an aggressive CRDM replacement / rebuild program (25-29 per outage). This replaces all drives within approximately 14 years (185 total drives). A rebuilt CRDM costs on average $1OOK. The SAMA would be associated with increasing the maintenance to improve the reliability. Doubling the replacement CM Mechanical failure of scram 2.077 2.15E-06 program frequency to 53 per outage would result in a system (NUREG/CR-5500) cost of 92.5*$100K = $9.2M over 7 years or $1.3M per year. The RRW importance measure of 1.246 corresponds to an estimated maximum benefit of

$100K. Therefore, this is not cost effective. SAMA candidate AT-09 to provide alternate rod insertion is already implemented at CGS. No additional SAMA candidates are required.

Used to meet modeling purpose (always 1.0). Defines GV-FAIL Guaranteed combustible gas 1.986 1.OOE+00 support system failure states that prohibit vent operation. Not a SAMA candidate.

SAMA candidates AT-10 and CP-12, which provide a Large containment breach due filtered containment vent to remove decay heat, toaTWSw containureahdue improve containment heat removal and venting L2-PHE-CLIVATWAS injection or LLOCA without 1.986 1.OOE+00 capability and reduce the probability of large vapor suppression containment breach. These candidates are evaluated in Table A-15. No additional SAMA candidates are required.

Any improvement in improving ECCS environmental capability requires multiple hardware modifications L2-PHE-ENV-FAILD Environmental conditions cause 1.986 100E÷00 such as replacing or protecting components. This loss of all RPV injection RRW is well below the cost of multiple hardware modifications that would be required. Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 59 of 173 Table A-10: Level 2 Internal Events Basic Events Importance List Event Label Description RRW 1 Point Comment/Resolution Estimate CmetRslto SAMA candidate CP-21, which strengthens containment, reduces the wetwell failure probability.

CP-21 is evaluated in Table A-1 5. SAMA candidate Wetwell failure below water line AT-1 5R, which installs modifications to make use of during ATWS HPCS more likely during ATWS, may reduce the wetwell failure frequency. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

Any improvement in improving RHR environmental capability requires multiple hardware modifications L2-PHE-RXENV-PMP Reactor Building environment 1.966 998E-0 such as replacing or protecting components. This fails RHR pumps RRW is well below the cost of multiple hardware modifications that would be required. Not a SAMA candidate.

SAMA OT-07R candidate evaluates improving Operator fails to prevent RPV procedures and operator training on systems and SLC-XHE-FO-LLVCT overflow due to uncontrolled 1.233 4.91 E-02 actions shown to be important by the PSA. This basic injection following event was included in SAMA candidate OT-07R. This depressurization candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FL-07R, which flood protects HPCS, reduces failure probability. SAMA candidates CC-01 HPS ----- ISLOCA-R HPCS unavailable due to 1.21 1.OOE+00 and CC-02, which provide an additional high pressure flooding from ISLOCA injection system, increases high pressure injection availability. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates CB-01, CB-03, CB-08, CB-09, which RHR / LPCS injection valve provide improved ISLOCA detection and response, RHR-LPS-ISLOCA-R unavailable -ISLOCA rupture in 1.21 1.OOE+00 improve mitigation and reduce the impact. These valve area SAMA candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

Any improvement in turbine trip frequency requires a TT Turbine Trip initiating event 1.195 7.1OE-01 major hardware modification. This RRW is below the frequency

$100K minimum value for a hardware modification. Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 60 of 173 Table A-10:

Level 2 Internal Events Basic Events Importance List Event Label Description RRW1 Point Comment/Resolution Estimate CmetRslto New SAMA candidate CB-1 OR, which evaluates Moderate MS leak in Turbine additional NDE and inspections of MS piping, detects IE-FLD-TLO--MS-U Building 1.135 5.61 E-04 pipe degradation and reduces the flooding frequency.

This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates CB-01, CB-03, CB-08, CB-09, which pprovide improved ISLOCA detection and response, RHRS-RP---241NLL RHR 24-inch pipe ruptures 1.121 7.48E-02 improve mitigation and reduce the impact. These during ISLOCA SAMA candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

L2-PHE-GVPHONAGA Containment inerted, vent/purge 1.12 9.90E-01 Success term. Not a SAMA candidate.

not required SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA MS-HUMNLOUMSH3LL Operator fails to isolate 1.108 6.30E-05 results. Although this basic event was not included in moderate MS BOC SAMA case OT-07R, this operator action will be identified for increased training.

This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA L2-HUMN-RCVR-SYS Operator fails to recover RPV 1.079 9.OOE-01 results. Although this basic event was not included in injection system SAMA case OT-07R, this operator action will be identified for increased training.

This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

High primary system L2-PHE-HPST-NFAL temperature does not cause 1.079 8.00E-01 Success term. Not a SAMA candidate.

failure L2-PHE-MSIV-S-L2 MSIVs or steam line unavailable 1.079 1.OOE+00 Used to meet modeling purpose (always 1.0). It is a in Level 2 conservative assessment. Not a SAMA candidate.

L2-PHE-SRV-NOPEN SRVs do not stick open 1.079 8.00E-01 Success term. Not a SAMA candidate.

L2-PHE-WHDNCF-MS Water hammer does not cause 1.079 7.OOE-01 Success term. Not a SAMA candidate.

failure of mechanical system I

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 61 of 173 Table A-10: Level 2 Internal Events Basic Events Importance List Event Label Description RRW 1 Point Comment/Resolution Estimate CmetRslto SAMA candidates FW-01 and FW-04, which provide FW upgrades, reduce Loss of FW frequency. FW-01 is already implemented at CGS. FW-04 is evaluated for TF Loss of FW initiating event 1.078 2.00E-01 cost-benefit. SAMA candidate FW-05R, which provides frequency manual control of RFW on loss of DC, reduces Loss of FW frequency. This candidate is also evaluated for cost-benefit. No additional SAMA candidates are required.

L2-PHE-HP-BLW-VS High pressure blowdown 1.074 1.OOE-01 This is a conservative assessment of an insignificant overwhelms vapor suppression phenomenon. Not a SAMA candidate.

Additional NDE and inspections were considered to detect pipe degradation and reduce the flooding frequency. At a minimum it would require a contractor Moderate RWCUJ leak in Reactor analysis of pipe failure rates and inspections in high IE-FLD-RLO-RWCUU Building 1.06 4.65E-04 radiation areas. A similar contractor analysis cost approximately $40K. Inspection costs are estimated to be similar or greater. The estimated maximum benefit for this basic event is $28K. Additional inspections are not cost effective. Not a SAMA candidate.

This should focus on improving condenser reliability.

Any improvement requires a major hardware TC Loss of Condenser initiating 1.06 1.60E-01 modification. This RRW is well below the $100K event frequency minimum value for a hardware modification. Not a SAMA candidate.

SAMA candidates CB-01, CB-03, CB-08, CB-09, which provide improved ISLOCA detection and response, RHRS-RP---181NLL RHR 18-inch pipe ruptures 1.055 6.94E-03 improve mitigation and reduce the impact. These during ISLOCA SAMA candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 62 of 173 Table A-10: Level 2 Internal Events Basic Events Importance List Event Label Description RRW 1 Point Comment/Resolution Estimate CmetRslto HPCS is currently highly reliable. Improvement beyond this is counter-productive to total unavailability. The ability to perform on-line maintenance in a timely manner (not just in refueling outages) is necessary to HPS --------- T3LL HPCS Unavailability due to test 1.049 1.36E-02 maintain high reliability. SAMA candidates CC-01 and

& maintenance (MR ule data)

CC-02, which provide additional high pressure injection, increase high pressure injection availability.

These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate AT-1 3, which automates SLC injection in response to ATWS, improves SLC reliability. SAMA SLCHUMN40MINH3XX Operator fails to initiate SLC for 1.046 1.89E-02 candidate OT-07R evaluates improving procedures and non-MSIV Closure during ATWS operator training. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

De-energizing RHR-V-8 was considered to reduce the risk of spuriously opening. At a minimum it would require an engineering evaluation, procedure changes, and an FSAR change. The estimated maximum benefit RHRV-MO----804XX MOV RHR-V-8 spuriously 1.044 3.24E-04 for this basic event is $21 K. If RHR-V-9 de-opened energization is taken into account, the RRW is 1.025, which corresponds to an estimated maximum benefit o

$12K (reference RHRV-MO ---- 904XX). Therefore, de-energizing RHR-V-8 to prevent spurious opening is not cost effective. Not a SAMA candidate.

RHR-V-9 is de-energized during online operations and RHRV-MO----904XX MOV RHR-V-9 spuriously 1.044 324E04 is not susceptible to spurious opening. This basic opened event is conservatively retained in the model. Not a SAMA candidate.

Any improvement in reducing RWCU-V-1 and RWCU-V-4 CCF requires a hardware modification such as RWCV-MO4AND1C3LL CCF of RWCU-V-1 and RWCU-1.044 3.30E-05 replacing a valve with a diverse component. This RRW V-4 is well below the $100K minimum value for a hardware modification. Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 63 of 173 Table A-10: Level 2 Internal Events Basic Events Importance List Event Label Description RRW1 Point Comment/Resolution Estimate CmetRslto SAMA candidates CB-01, CB-03, CB-08, CB-09, which MOV RHR-V-8 failed to hold on 1provide improved ISLOCA detection and response, RHRV-MO----8L3XX demand 1.036 2.70E-04 improve mitigation and reduce the impact. These SAMA candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates CB-01, CB-03, CB-08, CB-09, which MOV RHR-V-9 failed to hold on 1provide improved ISLOCA detection and response, RHRV-MO----9L3XX demand 1.036 2.70E-04 improve mitigation and reduce the impact. These SAMA candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate AT-1 3, which automates SLC injection in response to ATWS, improves SLC reliability. SAMA SLCHUMN20MINH3XX Operator fails to initiate SLC for 1.029 1.89E-02 candidate OT-07R evaluates improving procedures and MSIV Closure with ATWS operator training. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA Operator fails to inhibit ADS for 1.027 1.66E-02 results. Although this basic event was not included in AIM MSIV Closure with ATWS SAMA candidate OT-07R, this operator action will be identified for increased training. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates CP-1 8 and CP-27, which provide containment inerting and hydrogen control system L2-PHE-CONT-NOSI Containment not steam inerted 1.027 5.OOE-01 enhancements, reduce hydrogen deflagration probability. These candidates are evaluated in Table A-16. No additional SAMA candidates are required.

SAMA candidates CP-1 8 and CP-27, which provide containment inerting and hydrogen control system L2-PHE-H-DEFL-GL Hy 1.027 1.OOE+00 enhancements, reduce hydrogen deflagration probability. These candidates are evaluated in Table I_

A-16. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 64 of 173 Table A-10:

Level 2 Internal Events Basic Events Importance List Event Label Description RRW 1 Point Comment/Resolution Estimate CmetRslto SAMA candidates CP-18 and CP-27, which provide containment inerting and hydrogen control system L2-PHE-O2-INTRO-Operation deinerted or 02 1.027 1.OOE-02 enhancements, reduce hydrogen deflagration introduced probability. These candidates are evaluated in Table A-16. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training including this operator action. SAMA candidate AT-1 5R evaluates plant ATWH-HPLPRSTH3XX Operator fails to restart HPCS or 1.026 1.OOE+00 modifications that would improve the success of this LPCS-LPCI during ATWS operator action. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and actions shown to be important by the PSA. This basic RHRH-ATWSDC-H3XX Operator fails to bypass RHR-1.025 8.13E-01 event was included in SAMA candidate OT-07R. This SDC interlocks during ATWS candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

1 RRW values are based on LERF.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 65 of 173 Table A-11: Level 1 Fire Basic Events Importance List1 Event Label Description RRW Pointe Estimate CmetRslto EFF Early-Extinguish (Fixed Ignition 3.11 3.60E-01 Split Fraction factor (not developed). Not a SAMA Source) Fails candidate.

SAMA candidates FR-09R (area R-1 D) and FR-i 1 R (area RC-04) evaluate the installation of early detection GTFF50 50% Loss Of FW Trip 1.302 5.OQE-01 in fire areas where fires damage can lead to a 50%

loss of FW. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates FR-1 2R (T-1 D) and FR-i 1 R (areas RC-02, RC-03 and RC-08) evaluate the installation of GTFF 100% Loss of FW Trip 1.271 1.OOE+00 early detection in this fire area where fire damage can lead to a 100% loss of FW. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates FR-09R, FR-12R, FR-11 R, and FR-Early-Extinguish (Transient 1OR evaluate the installation of early detection in fire ETF Ignition Source) Fails 1.254 2.40E-01 areas of high risk importance. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates FR-09R (areas R-1B, R-1J) and FR-11R (areas RC-1A, RC-13) evaluate the installation of GTFF1 0 10% Loss Of FW Trip 1.219 1.OOE-01 early detection in fire areas where fires damage can lead to a 10% loss of FW. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

This is a conservative assumption of no offsite power recovery for the fire model. SAMA candidates AC/DC-10, AC/DC-1 5, AC/DC-28, AC/DC-29 and AC/DC-30R NO-OFFSITE-RECOV No Recovery Of Offsite Power 1.191 1.OOE+00 evaluate additional emergency AC power or the (Fire) reliability of emergency AC power. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 66 of 173 Table A-11: Level 1 Fire Basic Events Importance List' Event Label Description RRW Point Comment/Resolution Estimate Cmet~slto SAMA candidates FR-12R (area T-1A) and FR-11R (area RC-07) evaluate the installation of early detection GTTF50 50% Turbine Trip 1.169 5.OOE-01 in this fire area where fire damage can lead to a 50%

turbine trip. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

This is a conditional failure of HPCS lost due to Icontainment failure. SAMA candidates CC-01 and CC-CF-FAILS-INJECT Injection Fails Due to 1.155 8.30E-02 02 evaluate the addition of a redundant train of HPCS.

Containment Failure These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-1 1 R evaluates the installation of FW04 IE Zone: W04 1.142 1.02E-02 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-1 1 R evaluates the installation of FW07 Zoe:W0118

.early detection in this fire area. This candidate is 7IE Zone: W7 18 1.10E-02 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-1 1 R evaluates the installation of IFW04 Fixed Ignition Source Fraction 1.138 965E01 early detection in this fire area. This candidate is Zone: W04 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-i 1 R evaluates the installation of Fixed Ignition Source Fraction early detection in this fire area. This candidate is Zone: W07 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates AC/DC-10, AC/DC-15, AC/DC-28, DG System Does Not Continue AC/DC-29 and AC/DC-30R evaluate additional EACENG-EDG3-D424 To Run For 24 Hours 1.132 3.95E-02 emergency AC power or the reliability of emergency AC power. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 67 of 173 Table A-11: Level 1 Fire Basic Events Importance List1 Event Label Description RRW Point Comment/Resolution Estimate CmetRslto The ability to perform online maintenance in a timely manner (not just in refueling outages) is necessary to HPCS Unavailability due to Test

.118 1.36E02 maintain high reliability. SAMA candidates CC-01 and

& Maintenance (MRule data)

CC-02 evaluate the addition of redundant HPCS trains.

These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-11 R evaluates the installation of early detection in this fire area. This candidate is FW14 IE Zone: W14 1.117 7.51 E-03 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-12R (area T-1C) evaluates the installation of early detection in this fire area where GTTF 100% Turbine Trip 1.116 1.00E+00 fires damage can lead to a 100% turbine trip. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-08 was performed to evaluate improving fire resistance of RHR cables. This would RHR----A----T3LL RHR Train A Out Due to Testing 1.114 7.94E-03 help reduce the likelihood of failure of RHR Train B

& Maintenance from fire while RHR Train A is OOS. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-12R evaluates the installation of early detection in this fire area. This candidate is ETO I E Zone: Ti C 1.108 7.05E-03 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-12R evaluates the installation of Fixed Ignition Source Fraction early detection in this fire area. This candidate is Zone: T1C evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 68 of 173 Table A-1 1: Level 1 Fire Basic Events Importance List1 Point Event Label Description RRW Estimate Comment/Resolution RHR Train B has high reliability as indicated by the basic event importance value. Further improvement in reliability would require hardware changes or an additional shutdown heat removal system. An example is added a heat exchanger to RHR Train C with interconnecting piping similar to RHR Train A and B RHR----B----T3LL RHR Train B Out Due to Testing 1.091 796E03 with a connection to SW Train B. Since the benefit

& Maintenance from the RRW value is well below $1 00K, this basic event will not be considered further. SAMA candidate FR-08 was performed to evaluate improving fire resistance of RHR cables. This would help reduce the likelihood of failure of RHR Train B from fire while RHR Train A is OOS. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-i1 R evaluates the installation of IFW14 Fixed Ignition Source Fraction 1.087 953E01 early detection in this fire area. This candidate is Zone: W14 evaluated for-cost-benefit. No additional SAMA candidates are required.

Conditional Probability Fire In SAMA candidate FR-1 1 R evaluates the installation of FR1W14 SM-7 Switchgear And Large 1.087 8.08E-01 early detection in this fire area. This candidate is Transformer evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-i 1 R evaluates the installation of Fixed Ignition Source Fraction 1.077 950E01 early detection in this fire area. This candidate is IFW08 Zone:

.50E-0 Zone: W08 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-1 1R evaluates the installation of FW08IE Zne:

08

.0767.02-03 early detection in this fire area. This candidate is FW08 IE Zone: W08 1.076 7.02E-03 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-1 1 R evaluates the installation of FW03 IE Zone: W03 1.074 2.73E-04 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 69 of 173 Table A-11: Level 1 Fire Basic Events Importance List1 Event Label Description RRW Point Comment/Resolution Estimate CmetRslto This is the local relay box that the sensors feed. These are being changed out to a more reliable local panel FP-FCP --------

LL Failure Of Fire Control Panel 1.068 9.OOE-03 through a multi-year upgrade in the FP program. This is being implemented as part of an existing Appendix R upgrade program. Not a SAMA candidate.

SAMA candidate FR-09R evaluates the installation of FR1 D IE Zone: R1 D 1.06 2.77E-03 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-08 evaluates improving fire resistance of SW cables. This would help reduce the SW -----

A ---- T3LL SW Train A Unavailability due to 1.058 4.12E-03 likelihood of failure of SW Train B from fire while SW test & maintenance (MRule data)

Train A is OOS. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

This requires a DG room fire damper, which is a EXF Early Extinguish Failed (Power 1.057 3.60E-01 hardware modification. This RRW is well below the Transformer)

$100K minimum value for a hardware modification.

Not a SAMA candidate.

SAMA candidates AC/DC-1 0, AC/DC-15, AC/DC-28, AC/DC-29 and AC/DC-30R evaluate additional sources NREAC4-F Non-Recovery of Diesel in 4 1.056 1.OOE+00 of emergency AC power. These candidates are Hours - Fire evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-11 R evaluates the installation of FR3WO8 Conditional Probability Fire in E-1.054 9.09E-01 early detection in this fire area. This candidate is SM-8 and 8/85/2 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-09R evaluates the installation of FR1J IE Zone: RIJ 1.053 1.11E-02 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

This requires a DG room fire damper, which is a hardware modification. This RRW is well below the

$100K minimum value for a hardware modification.

Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 70 of 173 Table A-1 1: Level 1 Fire Basic Events Importance List' Point Event Label Description RRW Estimate Comment/Resolution SAMA candidate FR-08 evaluates improving fire resistance of SW cables. This would help reduce the SW -----

B ---- T3LL SW Ta t

1.048 2.83E-03 likelihood of failure of SW Train A from fire while SW (MRule Data)

Train B is OOS. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-09R evaluates the installation of IFRiJ Fixed Ignition Source Fraction 1047 864E01 early detectioh in this fire area. This candidate is Zone: RIJ evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-11 R evaluates the installation of FR2WO4 Conditional Probability Fire in TR-1.046 4.61 E-01 early detection in this fire area. This candidate is 7A/1, TR-IN3, S1/1 D, MC7A evaluated for cost-benefit. No additional SAMA candidates are required.

The ability to perform online maintenance in a timely manner (not just in refueling outages) is necessary to maintain high reliability. SAMA candidates AC/DC-1 4 Transformer TR-S Out For and AC/DC-27, which provide additional off-site power Maintenance (MRule Data) options, increase power availability. AC/DC-1 4 is evaluated in Table A-15. AC/DC-27 is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates AC/DC-1 0, AC/DC-15, AC/DC-28, DG-2 Out For Maintenance AC/DC-29 and AC/DC-30R evaluate additional EACEDG-2 ----

T3D2 (MRule Data) 1.046 1-.88E-02 emergency AC power or the reliability of emergency AC power. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and Operator Fails To Properly operator actions determined to be important from PSA CIAHUMNX-TIEH3-F Lock/Unlock CAS Cross-tie 1.041 1.20E-01 results. This basic event was included in SAMA Manual Valves When Required candidate OT-07R. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

HPCS-V-4 MO Gate Valve NC-Any improvement will require a hardware fix. The HPSV-MO ---- 4P2LL FTO 1.04 2.43E-03 worth of this RRW is well below the cost of a hardware FTO modification. Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 71 of 173 Table A-1 1: Level 1 Fire Basic Events Importance List' Event Label Description RRW Point Comment/Resolution Estimate'CmetRslto HPCS-V-12, Minimum Flow Any improvement will require a hardware fix. The HPSV-MO---12P2LL Protection Valve NC-FTO on 1.04 2.43E-03 worth of this RRW is well below the cost of a hardware Demand modification. Not a SAMA candidate.

SAMA candidate FR-i 1 R evaluates the installation of FWi 3 IE Zone: W13 1.037 2.48E-03 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates AC/DC-1 0, AC/DC-1 5, AC/DC-28, 2

DG-2 Does Not Continue To Run AC/DC-29 and AC/DC-30R evaluate additional EACENG-EDG2-S4D2 F26 Hours 1.036 1.00E-02 emergency AC power or the reliability of emergency AC power. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-07b evaluates improving the fire HS-EAC-TRS Hot Short Disables TR-S 1.036 3.OOE-01 resistance of cables to transformer TR-S. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-1 1 R evaluates the installation of IFW13 Fixed Ignition Source Fraction 1.035 8.57E-01 early detection in this fire area. This candidate is Zone: W13 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates FR-09R, FR-12R, FR-1 1 R and FR-1OR evaluate the installation of early detection in fire areas of high risk importance. This detection system is ECF Early Extinguish 1.035 1.90E-01 designed to sense fixed ignition sources sooner (Cabinet/electrical panel) Fails allowing improved early extinguishment. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-09R evaluates the installation of Fixed Ignition Source Fraction early detection in this fire area. This candidate is Zone: RID evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-i1 R evaluates the installation of FW1A IE Zone: W1iA 1.033 4.44E-03 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 72 of 173 Table A-1 1: Level 1 Fire Basic Events Importance List' Event Label Description RRW Point Comment/Resolution Estimate CmetRslto SAMA candidate FR-1 1 R evaluates the installation of FW02 IE Zone: W02 1.033 3.02E-04 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-03 evaluates installing additional CIA-V-30A Failure Caused By transfer and isolation switches to mitigate hot shorts HS-CIAV-MO30A Hot Short 1.033 3.OOE-01 including CIA-V-30A. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-03 evaluates installing additional transfer and isolation switches to mitigate hot shorts HS-CIAV-MO30B CIAV3oB Failure Caused By 1.032 3.OOE-01 including CIA-V-30B. This candidate is evaluated for Hot Short cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA CIAHUMNV104BH3-F Operator Fails To Open Manual 1.032 2.60E-01 results. This basic event was included in SAMA Block Valve CIA-V-104B (Fire) candidate OT-07R. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-03 evaluates installing additional transfer and isolation switches to mitigate hot shorts.

HS-ADS-OPEN is not specifically addressed in FR-03, HS-ADS-OPEN ADS Valve(S) Stuck Open Due 1.032 3.OOE-01 but basic events with higher RRW values are evaluated. This RRW is well below the cost of a hardware modification. No additional SAMA candidates are required.

SAMA candidate FR-i 1 R evaluates the installation of RC2-A Conditional Probability Not in 1.031 6.80E-01 early detection in this fire area. This candidate is Zone RC-2A evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 73 of 173 Table A-1 1: Level 1 Fire Basic Events Importance List' Event Label Description RRW Point Comment/Resolution Estimate Cmet~slto SAMA candidate OT-07R evaluates improving procedures and operator training on systems and COAerMtVrFailF To Open Manual 1operator actions determined to be important from PSA CIAHUMNV104AH3-F operaFails To 04a (Fire) 1.031 2.60E-01 results. This basic event was included in SAMA Block Valve CIA-V-i104a (Fire) candidate OT-07R. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

This basic event affects a DG room fire damper. This DMATE -----

32W2LL Temperature Sensor For DMA 1.03 1.85E-03 would require a hardware modification. This RRW is Damper 32 Loss Of Function well below the $100K minimum value for a hardware modification. Not a SAMA candidate.

This basic event affects a DG room fire damper. This DMATE -----

31W2LL Temperature Sensor For DMA 1.03 1.85E-03 would require a hardware modification. This RRW is Damper 31 Loss Of Function well below the $100K minimum value for a hardware modification. Not a SAMA candidate.

This requires a DG room fire damper, which is a Conditional Probability Fire in TR-hardware modification. This RRW is well below the 7-71

$100K minimum value for a hardware modification. No a SAMA candidate.

SAMA candidate FR-09R evaluates the installation of FRiC IE Zone: RiC 1.029 2.72E-03 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

This would require a hardware modification. This RRW FP-SENSOR -----

LL Failure of Fire Detection Sensor 1.029 4.OOE-03 is well below the $1 00K minimum value for a hardware modification. Not a SAMA candidate.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA Failure to Align SPC Early Prior 1.029 1.63E-04 results. Although this basic event was not included in to Loss of RCIC OT-07R, this operator action has been identified for increased training. SAMA candidate OT-07R has been evaluated for cost-benefit. No additional SAMA candidates are required.

Conditional Probability Fire In 1.028 2.22E-01 Partitioning factor of fire source (W04). Not a SAMA RPSMG, PP7AMG1S0001, TR7A candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 74 of 173 Table A-1 1: Level 1 Fire Basic Events Importance List' Event Label Description RRW Point Comment/Resolution Estimate CmetRslto FR2WO7 Conditional Probability Fire Not in 1.027 4.27E-01 Partitioning factor of fire source (W07). Not a SAMA Zone RC-2B1 candidate.

Assumed value (not developed). Not a SAMA NTF Fire Propagation 1.026 4.30E-01 cniae candidate.

This requires a DG room fire damper, which is a L2W14 No Propagation to Other 1.026 i00E+00 hardware modification. This RRW is well below the Equipment

$100K minimum value for a hardware modification.

Not a SAMA candidate.

SAMA candidate FR-i 1 R evaluates the installation of FW05 Zone W024 1early detection in this fire area. This candidate is F 5IE Zone: W5 1.024 1.95E-03 evaluated for cost-benefit. No additional SAMA candidates are required.

IFFiC Fixed Ignition Source Fraction 1.023 8.61 E-01 Ratio of fixed source to total source in R1C. Not a Zone: RIC SAMA candidate.

This requires a hardware modification. This RRW is EACENG-EDG2-R3D2 DG-2 Does Not Start 1.022 6.36E-03 well below the $1 00K minimum value for a hardware modification. Not a SAMA candidate.

Improvements in this fan would require a hardware modification. This RRW is well below the $1 00K Fan PRA-FN-1 B Does Not Start minimum value for a hardware modification. CGS has PRAAHUS--1B-S3LL Fn DRand 1.021 9.01 E-04 procedures in place to open doors and place portable fans in response to loss of HVAC in the SW pump house, which would be performed in this scenario. No additional SAMA candidates are required.

SAMA candidate FR-12R evaluates the installation of FT1A IE Zone: T1 A 1.021 2.36E-02 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates AC/DC-1 0, AC/DC-1 5, AC/DC-28, DG-1 Out For Maintenance AC/DC-29 and AC/DC-30R evaluate additional EACEDG-1.----T3D1 (MRule Data) 1.021 1.94E-02 emergency AC power or the reliability of emergency AC power. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 75 of 173 Table A-1 1: Level 1 Fire Basic Events Importance List1 Point Event Label Description RRW Estimate Comment/Resolution SAMA candidate CW-07 evaluates installing an additional SW pump. This candidate is evaluated for cost-benefit. Any additional improvements to increase Failure Of Standby SW Pump pump start reliability will require a hardware SW-P-MDSWP1 BS3LB Motor To Start On Demand, 1.021 8.84E-04 modification. This RRW is well below the $100K Mechanical minimum value for a hardware modification. It is unlikely that any hardware modification would significantly improve SW pump reliability to start. No additional SAMA candidates are required.

SAMA candidate FR-i 1 R evaluates the installation of IFW05 Fixed Ignition Source Fraction 1.021 8.18E-01 early detection in this fire area. This candidate is Zone: W05 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA OP-ECCS-SW Operator response to diagnose 1.02 1.OOE+00 results. Although this basic event was not included in lack of SW for manual alignment OT-07R, this operator action has been identified for increased training. SAMA candidate OT-07R has been evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate CW-07 evaluates installing an additional SW pump. This candidate is evaluated for cost-benefit. Any additional improvements to increase Conditional Probability of SW pump start reliability will require a hardware F-RHR-MOCSTRT Start Cause by RHR Pump Start 1.02 1.OOE+00 modification. This RRW is well below the $1 00K (MOC Assembly) minimum value for a hardware modification. It is unlikely that any hardware modification would significantly improve SW pump reliability to start. No additional SAMA candidates are required.

SAMA candidates AC/DC-1 0 and AC/DC-1 5 evaluate EACENG-EDG1-S4D1 DG-1 Does Not Continue to Run 1.02 1.00E02 additional emergency AC power redundant to DG-1.

for 6 Hrs These candidates are evaluated for cost-benefit. No I _additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 76 of 173 Table A-1 1: Level 1 Fire Basic Events Importance List' Event Label Description RRW Point Comment/Resolution

________________________Estimate CmetRslto SAMA candidate FR-10R evaluates the installation of FWl0*

IE Zone: W10 1.02 1.30E-02 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-12R evaluates the installation of IFTiA Fixed Ignition Source Fraction 1.019 979E01 early detection in this fire area. This candidate is Zone: T1A evaluated for cost-benefit. No additional SAMA candidates are required.

FR3WO7 Conditional Probability Fire Not in Ratio of certain fixed source to total fixed source in Zone: RC-2C RC07. Not a SAMA candidate.

SAMA candidate AC/DC-30R provides an additional diesel diverse for DG-1 and DG-2. SAMA candidate CC-24R evaluates backfeeding the HPCS system EACENG-EDG3-R3D3 DG-3 Does Not Start 1.018 6.36E-03 (supplied by DG-3) from SM-8 to provide an additional HPCS AC power source. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

CGS procedures are in place to open doors and place portable fans in response to loss of HVAC in the SW Fan PRA-FN-1A Does Not Start pump house, which would be performed in this PRAAHUS-1A-S3LL On Demand 1.018 9.01 E-04 scenario. SAMA candidate HV-03 evaluates enhancing procedures to respond to loss of HVAC.

This candidate is already implemented at CGS. No additional SAMA candidates are required.

Auto Suppression - This requires a hardware FP-V-CLAPPERW2LL Failure of Deluge Valve to Open 1.018 2.49E-03 modification. This RRW is well below the $1 00K minimum value for the hardware modification. Not a SAMA candidate.

SAMA candidate FR-12R evaluates the installation of FR1 L IE Zone: R1 L 1.018 2.65E-02 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 77 of 173 Table A-11: Level 1 Fire Basic Events Importance List1 Point Event Label Description RRW Estimate Comment/Resolution SAMA candidate CW-07 evaluates installing an additional SW pump. This candidate is evaluated for cost-benefit. Any additional improvements to increase Failure of Standby SW Pump pump start reliability will require a hardware SW-P-MDSWP1AS3LA Motor to Start On Demand, 1.017 8.84E-04 modification. This RRW is well below the $100K Mechanical minimum value for a hardware modification. It is unlikely that any hardware modification would significantly improve SW pump reliability to start. No additional SAMA candidates are required.

HPCS-V-15 NC-FTO for CST to This requires a hardware modification. This RRW is HPSV-MO---15P2LL Suppression Pool Suction 1.017 2.43E-03 well below the $1 00K minimum value for a hardware Transfer modification. Not a SAMA candidate.

IFRIL Fixed Ignition Source Fraction 1.017 9.43E-01 Ratio of fixed source to total source in RI L. Not a Zone: R1L SAMA candidate.

SAMA candidate AT-08 provides increased SRV reseat reliability. This candidate has already been PP-1 Probability of SORV in Period 1.017 4.90E-01 implemented at CGS based on the fact that CGS has from 12-24 Hours an extensive SRV testing program that includes testing SRVs at plant startup for both opening and reseating.

No additional SAMA candidates are required.

IFW1A Fixed Ignition Source Fraction 1.017 8.90E-01 Ratio of fixed source to total source in RC1A. Not a Zone: WlA SAMA candidate.

FR6W14 Conditional Probability Fire in TR-1.017 1.18E-01 Ratio of certain fixed source to total fixed source in 7-73 RC14. Not a SAMA candidate.

DG-3 has high reliability as indicated by the RRW value provided. Further improvement in reliability requires hardware changes. This RRW is well below the $1 00K DG-3 Out For Maintenance minimum value for a hardware modification. SAMA EACEDG-3 ---- T3D3 (MRule Data) 1.017 1.03E-02 candidate CC-24R evaluates backfeeding the HPCS (powered by DG-3) from SM-8, thereby providing an additional AC power source to HPCS. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

HPCS-RMS-P/1 (E22B-S2)

This requires a hardware modification. This RRW is HPSRMS ---- S2W2LL Switch Failure 1.017 1.08E-03 well below the $1 00K minimum value for a hardware SwitchFailureI modification. Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 78 of 173 Table A-1i1: Level 1 Fire Basic Events Importance List' Point Event Label Description RRW Estimate Comment/Resolution This requires a hardware modification. This RRW is RHRP-MD---2AS3LL RHR-P-2A Motor Driven Pump 1.016 8.84E-04 well below the $100K minimum value for a hardware Fails to Start modification. Not a SAMA candidate.

Ratio of critical cabinets to total cabinets in the Control IGCCWl0 Fire Starts in Critical Cabinet 1.016 1.54E-01 RomNtaSAAcnite Room. Not a SAMA candidate.

This requires a hardware modification. This RRW is LTS5W14 TR-7-71 Oil Fire Spreads to TR-S 1.015 5.00E-01 well below the $100K minimum value for a hardware modification. Not a SAMA candidate.

This requires a hardware modification. This RRW is RHRP-MD---2BS3LL RHR-P-2B Motor Driven Pump 1.015 8.84E-04 well below the $100K minimum value for a hardware Fails to Start modification. Not a SAMA candidate.

1 In Reference 3, the response to RAI 5.d provided a similar table of basic events important to the FPSA; the basic events were first sorted on RAW then on RRW. For Table A-11, the sorting was purely by RRW.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 79 of 173 Table A-12: Level 2 Fire Basic Events Importance List Point Event Label Description RRW 1 Estimate Comment/Resolution EFF Early-Extinguish (Fixed Ignition 4.229 3.60E-01 Split Fraction factor (not developed).. Not a SAMA Source) Fails candidate.

L2-PHE-GVPHONAGA Containment Inerted Vent/Purge 3.6 9.90E-01 This is a success term. Not a SAMA candidate.

Not Required SAMA candidate CP-18 evaluates post accident L2-PHE-02-INTRO-Operation Deinerted or 02 1.858 1.00E-02 containment inerting capability. This candidate is Introduced evaluated in Table A-16. No additional SAMA candidates are required.

L2-PHE-H-DEFL-GL Hydrogen Deflagration Occurs 1.858 1.OOE+00 Phenomenological Value (Assumed). Not a SAMA Globally candidate.

L2-PHE-CONT-NOSI Contain ment Not Steam Inerted 1.858 5.00E-01 Phenomenological Value (assumed 0.5). Not a SAMA candidate.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA l1.732 9.OOE-01 results. Although this basic event was not included in SAMA candidate OT-07R, this operator action has been identified for increased training. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates FR-09R (area R-1 D) and FR-i 1 R (area RC-04) evaluate the installation of early detection GTFF50 50% Loss Of FW Trip 1.69 5.OOE-01 in fire areas where fires damage can lead to a 50% loss of FW. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

This basic event conservatively represents a large leak in a pressurized water reactor hatch. Containment hatches are tested at CGS prior to restart to insure no latent large leak exists. In addition, 02 monitoring L2-PHESM-PRXST-F Pre-existing Failure 1.292 2.70E-01 while the containment is inerted will reveal any significant leak in the containment. Large pre-existing containment leaks in inerted containments are considered very unlikely because of likely detection.

Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 80 of 173 Table A-12: Level 2 Fire Basic Events Importance List Event Label Description RRW1 E Point Comment/Resolution Estimate High Primary System L2-PHE-HPST-NFAL Temperature Does Not Cause 1.236 8.00E-01 Success term. Not a SAMA candidate.

Failure L2-PHE-MSIV-S-L2 MSIVs or Steam Line Unavailable 1.236 1.00E+00 Phenomenological Value (Assumed 1.0). Not a SAMA in Level 2 candidate.

SAMA candidate AT-08 evaluates improving SRV L2-PHE-SRV-NOPEN SRVs Do Not Stick Open 1.236 8.00E-01 reseat reliability. This candidate has already been implemented at CGS. No additional SAMA candidates are required.

L2-PHE-WHDNCF-MS Water Hammer Does Not Cause 1.236 7.00E-01 Success term. Not a SAMA candidate.

Failure of Mechanical System L2-PHE-HP-BLW-VS High Pressure Blowdown 1.219 1.00E-01 Phenomenological Value (Vapor Suppression Failure Overwhelms Vapor Suppression assumed value 0.1). Not a SAMA candidate.

SAMA candidates FR-09R (areas R-1 B, R-1 J) and FR-11R (areas RC-1A, RC-13) evaluate the installation of GTFF10 10% Loss Of FW Trip 1.211 1.00E-01 early detection in fire areas where fires damage can lead to a 10% loss of FW. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates FR-09R, FR-12R, FR-11 R, and FR-1OR evaluate the installation of early detection in fire ETF Early-Extinguish (Transient 1.201 2.40E-01 areas of high risk importance. These candidates are Ignition Source) Fails evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-09R evaluates the installation of FR1 D IE Zone: R1 D 1.188 2.77E-03 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates CC-01 and CC-02 evaluate the HPS-T3LL HPCS unavailability due to test &

1.187 1.36E-02 additions of redundant HPCS trains. These candidates maintenance (MRule data) are evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 81 of 173 Table A-12: Level 2 Fire Basic Events Importance List Point Event Label Description RRW 1 Estimate Comment/Resolution SAMA candidates AC/DC-1 0, AC/DC-15, AC/DC-28, EACENG-EDG3-SFR-DG System Does Not Continue AC/DC-29 and AC/DC-30R evaluate additional 11 R (42)4 To Run For 24 hrs 1.172 3.95E-02 emergency AC power or the reliability of emergency AC power. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-1 1 R evaluates the installation of FW04 IE Zone: W04 1.16 1.02E-02 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-1 1R evaluates the installation of IFW4Fixed Ignition Source Fraction 1.159 9.65E-0 ly detection in this fire area. This candidate is Zone: W04 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-12R (T-1C) evaluates the installation of early detection in this fire area where fire GTTF 100% Turbine Trip 1.153 1.00E+00 damage can lead to a 100% turbine trip. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-1 2R evaluates the installation of FTlC I E Zone: T1C 1.153 7.05E-03 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-12R evaluates the installation of IFTiC Fixed Ignition Source Fraction 1.149 943E01 early detection in this fire area. This candidate is Zone: T1C evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving Operator Fails To Properly procedures and operator training on systems and CIAHUMNX-TIEH3-F Lock/Unlock CAS Cross-tie 1.141 1.20E-01 operator actions determined to be important from PSA Manual Valves When Required results. This candidate is evaluated for cost-benefit.

No additional SAMA candidates are required.

SAMA candidate FR-09R evaluates the installation of Fixed Ignition Source Fraction early detection in this fire area. This candidate is IFR1 oe iD 1.139 8.63E-01 lydtcinithsfrae.Tisaddtes DZone: R1D evaluated for cost-benefit. No additional SAMA I

I_ candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 82 of 173 Table A-12: Level 2 Fire Basic Events Importance List Point Event Label Description RRW1 Estimate Comment/Resolution SAMA candidates FR-1 2R (T-1 D) and FR-i 1 R (RC-02, RC-03, RC-08) evaluate the installation of early detection in fire areas where fires damage can lead to a 100% loss of FW. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-09R evaluates the installation of FRIC IE Zone: R1C 1.12 2.72E-03 early detection in this fire area. This candidate is CZ :evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-09R evaluates the installation of FRIJ IE Zone: R1J 1.117 1.11 E-02 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-03 evaluates installing additional CIA-V-30A Failure Caused By Hot transfer and isolation switches to mitigate hot shorts HS-CIAV-MO30A Short 1.108 3.00E-01 including CIA-V-30A. This candidate is evaluated for S

cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and CIAHUMNV104BH3-F Operator Fails To Open Manual 1.108 2.60E-01 operator actions determined to be important from PSA Block Valve CIA-V-i104B (Fire) results. This candidate is evaluated for cost-benefit.

No additional SAMA candidates are required.

SAMA candidate FR-09R evaluates the installation of IFR1J Fixed Ignition Source Fraction 1.106 864E01 early detection in this fire area. This candidate is Zone: RIJ evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates FR-11R (RC-07) and FR-12R (T-1A) evaluate the installation of early detection in this fire GTTF50 50% Turbine Trip 1.106 5.OOE-01 area where fire damage can lead to a 50% turbine trip.

These candidates are evaluated for cost-benefit. No I additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 83 of 173 Table A-12: Level 2 Fire Basic Events Importance List Point Event Label Description RRW 1 Estimate Comment/Resolution SAMA candidate OT-07R evaluates improving procedures and operator training on systems and CIAHUMNV104AH3-F Operator Fails To Open Manual 1.105 2.60E-01 operator actions determined to be important from PSA Block Valve CIA-V-i104A (Fire) results. This candidate is evaluated for cost-benefit.

No additional SAMA candidates are required.

SAMA candidate FR-03 evaluates installing additional transfer and isolation switches to mitigate hot shorts HS-CIAV-MO30B CIAV30B Failure Caused By Hot 1.105 3.00E-01 including CIA-V-30B. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA L2-HUMN-OPTM-RPV Operator Fails to Depressurize in 1.104 5.20E-02 results. Although this basic event was not included in Level 2 (Conditional)

SAMA case OT-07R, this operator action has been identified for increased training. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-1 1 R evaluates the installation of FW07 IE Zone: W07 1.101.

1.10E-02 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-i 1 R evaluates the installation of IFW07 Fixed Ignition Source Fraction 1.1 9.68E-01 early detection in this fire area. This candidate is Zone: W07 evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-08 evaluates improving fire resistance of SW cables. This would help reduce the SW -----

B ---- T3LL (Mrule Data) 1.097 2.83E-03 likelihood of failure of SW Train B from fire while SW Train A is OOS. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-09R evaluates the installation of Fixed Ignition Source Fraction early detection in this fire area. This candidate is Zone: R1C evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 84 of 173 Table A-12: Level 2 Fire Basic Events Importance List Point Event Label Description RRW1 Estimate Comment/Resolution SAMA candidates AC/DC-14 and AC/DC-27, which Transformer TR-S Out For provide additional off-site power options, increase EACTRL-S ----

T3--

Maintenance (MRule Data) 1.086 1.46E-03 power availability. AC/DC-14 is evaluated in Table A-

15. AC/DC-27 was evaluated for cost-benefit. No additional SAMA candidates are required.

Control Rods Melt Prior to Fuel 1Phenomenological Value (Assumed 1.0). Not a SAMA L2-PHE-CNTRODMLT otoIRods od etPirt ul 1.065 1,00OE+00 cniae Rods candidate.

L2-PHE-RDINTGFLD Fuel Rod Integrity is Maintained 1.065 1.00E-01 Phenomenological Value (Assumed 1.0). Not a SAMA During Reflood candidate.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA L2-HUMN-RINJ-RDM Operator Restores Injection After 1.065 1.OOE+00 results. Although this basic event was not included in Control Rods Melt SAMA case OT-07R, this operator action has been identified for increased training. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

FR2WO4 Conditional Probability Fire In TR-1057 4.61 E01 Fraction of Fixed Source in Reactor Building 467'. Not 7A/1, TR-IN3, S1/1D, MC7A a SAMA candidate.

SAMA candidate FR-i 1 R evaluates the installation of FW14 IE Zone: W14 1.056 7.51 E-03 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-i 1 R evaluates the installation of FW03 IE Zone: W03 1.054 2.73E-04 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-08 evaluates improving fire resistance of SW cables. This will help reduce the SW -

A ---- T3LL SW-A Unavailability From Testing 1.05 4.12E-03 likelihood of failure of SW Train B from fire while SW and Maintenance (MRule Data)

Train A is OOS. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

This is the local relay box that the sensors feed. These FP-FCP-

-LL Failure Of Fire Control Panel 1.048 9.OOE-03 are being changed out to a more reliable local panel through a multi-year upgrade in the FP program. Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 85 of 173 Table A-12: Level 2 Fire Basic Events Importance List Point Event Label Description RRW1 Estimate Comment/Resolution SAMA candidate FR-1 1 R evaluates the installation of IFW4Fixed Ignition Source Fraction 1.045 9.53E-0 ly detection in this fire area. This candidate is Zone: W14 evaluated for cost-benefit. No additional SAMA candidates are required.

Conditional Probability Fire In SM-SAMA candidate FR-1 1 R evaluates the installation of FR1W14 7 switchgear and Large 1.045 8.08E-01 early detection in this fire area. This candidate is transformer evaluated for cost-benefit. No additional SAMA candidates are required.

This is a conservative assumption of no offsite power recovery for the fire model. SAMA candidates AC/DC-10, AC/DC-1 5, AC/DC-28, AC/DC-29 and AC/DC-30R NO-OFFSITE-RECOV No Recovery Of Offsite Power 1.044 1.00E+00 evaluate additional emergency AC power or the (Fire) reliability of emergency AC power. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

L2-PHE-AC-RX-FS-Failure to Recover AC Prior to 1.043 1 OOE+00 Phenomenological Value (new model). Not a SAMA Vessel Fail (Fire or Seismic) candidate.

Guaranteed Combustible Gas This basic event is used to meet modeling purpose GV-FAIL Vent Not Available 1.043 1.OOE+00 (always 1.0). Defines support system failure states that prohibit vent operation. Not a SAMA candidate.

SConditional Probability In MC-8B, 1.043 3.55E-Partitioning Factor of Fixed Source in Reactor Building 7B, IR72 PP7BC, FC11, TRTBC 471' (RIJ). Not a SAMA candidate.

SAMA candidate FR-09R evaluates the installation of FR1B IE Zone: R1B 1.042 1.17E-03 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate AC/DC-28 evaluates reducing CCF between DG-3 and DG-1/2. SAMA candidates AC/DC-EACEDG-123FRC3LL CCF Of All 3 DG Fail To Run 1.038 5.43E-05 10, AC/DC-29 and AC/DC-30R evaluate adding diverse diesels. SAMA candidate AC/DC-15 evaluates adding a gas turbine. These candidates are evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 86 of 173 Table A-12: Level 2 Fire Basic Events Importance List Point Event Label Description RRW1 Estimate Comment/Resolution SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA L2-HUMN--INJ-SLC Operator Fails to Inject SLC with 1.037 5.80E-03 results. Although this basic event was not included in Boron for Low Water Level SAMA case OT-07R, this operator action has been identified for increased training. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

Improvements in this fan require a hardware modification. This RRW is well below the $1 00K minimum value for a hardware modification. CGS PRAAHUS--1B-S3LL Fan PRAFNI B Does Not Start 1.036 9.01 E-04 procedures are in place to open doors and place On Demand portable fans in response to loss of HVAC in the SW pump house, which would be performed in this scenario. No additional SAMA candidates are required.

SAMA candidate FR-03 evaluates installing additional transfer and isolation switches for CIA-MO-20 to HS-CIAV-MO20 CIAHMOt20 Failure Caused By 1.036 3.OOE-01 mitigate any resulting hot shorts. This candidate is Hot Short evaluated for cost-benefit. No additional SAMA candidates are required.

This term comes from Internal Events PSA and represents the SW-B Pump Motor not started on SW-P-MDSWP1BS3LB Failure Of SW Pump Motor To 1.036 884E04 demand. Additional improvement requires a hardware Start On Demand, Mechanical modification. The RRW is well below the $1 00K minimum value for a hardware modification. Not a SAMA candidate.

SAMA candidates AC/DC-10, AC/DC-15, AC/DC-28, DG-2 Out For Maintenance AC/DC-29 and AC/DC-30R evaluate additional EACEDG-2 ---- T3D2 (MRule Data) 1.034 1.88E-02 emergency AC power or the reliability of emergency AC power. These candidates are evaluated for cost-benefit.

No additional SAMA candidates are required.

SAMA candidates AC/DC-1 0, AC/DC-1 5, AC/DC-28, DG-2 Does Not Continue To Run AC/DC-29 and AC/DC-30R evaluate additional EACENG-EDG2-S4D2 For 6 Hours 1.034 1.OOE-02 emergency AC power or the reliability of emergency AC power. These candidates are evaluated for cost-benefit.

No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 87 of 173 Table A-12: Level 2 Fire Basic Events Importance List Point Event Label Description RRW1 Estimate Comment/Resolution SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA Operator Fails To Initiate ADS results. Although this basic event was not included in DEP-ADS-SLC And SLC On Low RPV Water 1.033 2.60E-05 sAAcse A

Tthoug this oator act has been LevelSAMA case OT-07R, this operator action has been Level identified for increased training. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

L2R1D No Propagation To Other 1.033 5.09E-01 Partitioning Factor of Fixed Source in Reactor Building Equipment 471' (R1D). Not a SAMA candidate.

L Ex-Vessel Steam Explosion 1.033 1.00E-03 Phenomenological Value (Assumed 1 E-3). Not a L2-PHEXVESSEXP SAMA candidate.

SAMA candidate FR-09R evaluates the installation of Fixed Ignition Source Fraction 1.032 6.76E-01 ly detection in this fire area. This candidate is Zone: RIB evaluated for cost-benefit. No additional SAMA candidates are required.

This requires a hardware modification. This RRW is HS-ADS-OPEN ADS Valve(s) Stuck Open Due To 1.031 3.OOE-01 well below the $1 00K minimum value for a hardware Hot Short modification. Not a SAMA candidate.

FRiW04 Conditional Probability Fire In 1.031 222E01 Partitioning Factor of Fixed Source (W04). Not a RPSMG, PP7AMG1S0001, TR7A SAMA candidate.

Any improvement requires a hardware fix. The worth of HPSV-MO ---- 4P2LL HPCSV4 Motor Operated Gate 1.03 2.43E-03 this RRW is well below the $1 00K minimum value for a Valve NC-FTO hardware modification. Not a SAMA candidate HPCS-V-12, Minimum Flow Any improvement requires a hardware fix. The worth of HPSV-MO---12P2LL Protection Valve NC-FTO on 1.03 2.43E-03 this RRW is well below the $100K minimum value for a Demand hardware modification. Not a SAMA candidate Any improvement requires a hardware fix. The worth of ECF Early extinguish 1.028 1.90E-01 this RRW is well below the $100K minimum value for a (Cabinet/electrical panel) Fails hardware modification. Not a SAMA candidate FR3R1 D Conditional Probability I\\in E-IR-1.027 569E01 Partitioning Factor of Fixed Source in Reactor Building 62 MS-FN-1, H22-P009 I 471' (Ri D). Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 88 of 173

'Table A-12: Level 2 Fire Basic Events Importance List Event Label Description RRW1 Point Comment/Resolution Estimate CmetRslto SAMA candidate CC-24R evaluates backfeeding the DG-3 Out For Maintenance HPCS (powered by DG-3) from SM-8, thereby EACEDG-3 -- T3D3 le1.026 1.03E-02 providing an additional AC power source to HPCS. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

This requires a hardware modification. This RRW is HS-RHRV-MO-27A RHR-V-27A Failure Caused By 1.026 3.00E-01 well below the $100K minimum value for a hardware Hot Short modification. Not a SAMA candidate.

This would require a hardware modification. This RRW HS-RHRV-MO-17B RHR-V-17B Failure Caused By 1.024 3.OOE-01 is well below the $1OOK minimum value for a hardware Hot Short.

modification. Not a SAMA candidate.

This would require a hardware modification. This RRW HS-RHRV-MO-16B RHRV16B Failure Caused By 1.024 3.OOE-01 is well below the $100K minimum value for a hardware Hot Short modification. Not a SAMA candidate.

This would require a hardware modification. This RRW EACENG-EDG3-R3D3 DG-3 Does Not Start 1.024 6.36E-03 is well below the $100K minimum value for a hardware modification. Not a SAMA candidate.

L2-PHE-ISLOCA-F-ISLOCA During Core Melt 1.023 4.OOE-04 Phenomenological Value. Not a SAMA candidate.

Progression SAMA candidate FR-i 1 R evaluates the installation of FW05 IE Zone: W05 1.023 1.95E-03 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

131C No Propagation to Other 1.023 7.6E-01 Ratio of certain equipment in R1C. Not a SAMA Equipment candidate.

SAMA candidate FR-i 1 R evaluates the installation of FW02 IE Zone: W02 1.022 3.02E-04 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate FR-i 1 R evaluates the installation of Fixed Ignition Source Fraction early detection in this fire area. This candidate is Zone: W05 evaluated for cost-benefit. No additional SAMA candidates are required.

This would require a hardware modification. This RRW DMATE -----

32W2LL Temperature Sensor For DMA 1.021 1.85E-03 is well below the $100K minimum value for a hardware Damper 32 Loss Of Function modification. Not a SAMA candidate.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 89 of 173 Table A-12: Level 2 Fire Basic Events Importance List Point Event Label Description RRW 1 Estimate Comment/Resolution This would require a hardware modification. This RRW DMATE -----

31W2LL Temperature Sensor For DMA 1.021 1.85E-03 is well below the $100K minimum value for a hardware Damper 31 Loss Of Function modification. Not a SAMA candidate.

IFW08 Fixed Ignition Source Fraction 1.021 9.50E-01 Ratio of Fixed Source to Total Source in W08. Not a Zone: W08 SAMA candidate SAMA candidate FR-i 1 R evaluates the installation of FW08 IE Zone: W08 1.02 7.02E-03 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidates AC/DC-10, AC/DC-1 5, AC/DC-28, AC/DC-29 and AC/DC-30R evaluate additional EACEDG-1 ---- T3D1 DG-1 Out For Maintenance 1.02 1.94E-02 emergency AC power or the reliability of emergency AC (MRule Data) power. These candidates are evaluated for cost-benefit.

No additional SAMA candidates are required.

SAMA candidates AC/DC-1 0, AC/DC-15, AC/DC-28, D

DG-i Does Not Continue To Run AC/DC-29 and AC/DC-30R evaluate additional EACENG-EDG1-S4D1 For6 6Hrs 1.02 1.00E-02 emergency AC power or the reliability of emergency AC power. These candidates are evaluated for cost-benefit.

No additional SAMA candidates are required.

This would require a hardware modification. This RRW FP-SENSOR -----

LL Failure Of Fire Detection Sensor 1.019 4.OOE-03 is well below the $1 00K minimum value for a hardware modification. Not a SAMA candidate.

SAMA candidate FR-11 R evaluates the installation of RC2-A Conditional Probability Not in 1019 680E01 early detection in this fire area. This candidate is Zone RC-2A evaluated for cost-benefit. No additional SAMA candidates are required.

This would require a hardware modification. This RRW EXF Early Extinguish Failed (Power 1.019 3.60E-01 is well below the $1 00K minimum value for a hardware Transformer) modification. Not a SAMA candidate.

This would require a hardware modification. This RRW EACENG-EDG2-R3D2 DG-2 Does Not Start 1.019 6.36E-03 is well below the $1 00K minimum value for a hardware modification. Not a SAMA candidate.

SAMA candidate FR-1 1 R evaluates the installation of FR3WO8 Conditional Probability Fire in E-1.018 909E01 early detection in this fire area. This candidate is SM-8 and 8/85/2 evaluated for cost-benefit. No additional SAMA candidates are required.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 90 of 173 Table A-12: Level 2 Fire Basic Events Importance List Point Event Label Description RRW1 Estimate Comment/Resolution SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA Operator Fails To Initiate ADS 1.017 2.50E-05 results. Although this basic event was not included in DEP-ADS-HPCS and HPCS SAMA case OT-07R, this operator action has been identified for increased training. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

This would require a hardware modification. This RRW NXF Transformer Fire Involvinrg Oil 1.017 2.OOE-01 is well below the $100K minimum value for a hardware modification. Not a SAMA candidate.

This would require a hardware modification. This RRW EACEDG-123FSC3LL CCF Of All 3 DG Fail To Start 1.016 2.32E-05 is well below the $100K minimum value for a hardware modification. Not a SAMA candidate.

SAMA candidate FR-1OR evaluates the installation of FW10 I E Zone: W10 1.015 1.30E-02 early detection in this fire area. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

SAMA candidate OT-07R evaluates improving procedures and operator training on systems and operator actions determined to be important from PSA results. Although this basic event was not included in SAMA case OT-07R, this operator action has been identified for increased training. This candidate is evaluated for cost-benefit. No additional SAMA candidates are required.

1 RRW values are based on LERF.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 91 of 173 Table A-13: Level 1 Seismic Basic Events Importance List Event Label Description RRW Point Comment/Resolution Estimate CmetRslto Used to meet modeling purpose (always 1.0). Seismic SEIS-MITGTN-FAIL No mitigation for seismic failure of

.E+00 failure of the RPV and key buildings is conservatively RPV and/or Category I buildings modeled as leading to core damage. See Basic Event SDS42 for applicable failures. Not a SAMA candidate.

SAMA CP Strengthen containment would increase SDS42 Failure of RPV and/or Category 1.960 2.38E-06 the seismic capability. CP-21 is evaluated in Table A-buildings

15. No additional SAMA candidates are required.

This should focus on improving SSEL seismic capability. Any improvement would require multiple hardware modifications such as replacing or strengthening components. This RRW is well below the cost of multiple hardware modifications that would be required. Not a SAMA candidate.

Probability of short-term core Used to meet modeling purpose. Defines the SEIS-LONGTERM damage sequence for failure of 1.203 5.0OE-01 probability of short-term versus long-term core damage SSEL equipment versus long-sequences. See Basic Event SDS41 for applicable term core damage sequence sequences. Not a SAMA candidate

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 92 of 173 Table A-14: Level 2 Seismic Basic Events Importance List Point Event Label Description RRW1 Estimate Comment/Resolution Used to meet modeling purpose (always 1.0).

No mitigation for seismic failure of 3Seismic failure of the RPV and key buildings is SEIS-MITGTN-FAIL No and/or Category I buildings 34.513 1.00E+00 conservatively modeled as leading to core damage.

See basic event SDS42 for applicable failures. Not a SAMA candidate SAMA candidate CP-21, which strengthens SDS42 Failure of RPV and/or Category I 32.374 238E06 containment, increases the seismic capability. This buildings candidate is evaluated in Table A-15. No additional SAMA candidates are required.

Used to meet modeling purpose. Defines the split SEIS-CONT-BYP Split fraction of seismic structure 22.651 7.50E-01 fraction of seismic structure failures that bypass failures that bypass containment containment. See basic event SDS42 for applicable failures. Not a SAMA candidate.

L2-PHE-WHDNCF-MS Water hammer does not cause 1.033 7.OOE-01 Success term. Not a SAMA candidate.

failure of mechanical system L2-PHE-HPST-NFAL High primary system temperature 1.033 8.OOE-01 Success term. Not a SAMA candidate.

does not cause failure L2-PHE-SRV-NOPEN SRVs do not stick open 1.033 8.OOE-01 Success term. Not a SAMA candidate.

1 RRW values are based on LERF.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 93 of 173 Table A-15: QUALITATIVE SCREENING OF SAMA CANDIDATES (ORIGINALLY SCREENED AS CRITERION D "EXCESSIVE IMPLEMENTATION COST")

Modification Revised Basis for Screening/

SAMA ID Mdfcto eie (Potential Enhancement)

Criteria Modification Enhancements AC/DC-14 Install an additional buried offsite D

The cost of implementing a similar SAMA candidate at Arkansas Nuclear One power source Unit 2 was estimated by Entergy Operations to require more than $25,000,000 in 2005. The cost associated with the implementation of this SAMA exceeds the maximum attainable uncertainty benefit. Therefore, this SAMA candidate is not considered for further evaluation.

AC/DC-26 Bury off-site power lines.

D To realize a significant benefit from this SAMA candidate, the length of power lines buried must be significant. The cost of implementing a similar SAMA candidate at Arkansas Nuclear One Unit 2 was estimated by Entergy Operations to require more than $25,000,000 in 2005. The cost associated with the implementation of this SAMA exceeds the maximum attainable uncertainty benefit. Therefore, this SAMA candidate is not considered for further evaluation.

AT-10 Install an ATWS sized filtered D

The conceptual design of an ATWS-sized cooling vent would require establishing containment vent to remove decay a sufficiently-sized Class 1 hard pipe vent from the wetwell to a very large gravel heat.

containment tank with heat dissipation capability, filtered vents and processing drains. Current penetrations would not be suitable. Conversion of the wetwell equipment hatch would be required to provide dual function of venting and outage access. The hard piping out of the wetwell hatch and to a suitable structure outside of the reactor building would require penetration of the reactor building and strengthening of the building support system to a large gravel/tank located south of the building (only area available). Underground drainage would be required of Class 1 fill soils. Modification of security features would be necessary. Design, NRC approval of the design, material, installation, and revision of procedures and security and emergency plans would be required. A CGS cost estimate for this SAMA candidate is greater than $12,000,000. The cost associated with the implementation of this SAMA exceeds the maximum attainable uncertainty benefit. Therefore, this SAMA candidate is not considered for further evaluation.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 94 of 173 Table A-15: QUALITATIVE SCREENING OF SAMA CANDIDATES (ORIGINALLY SCREENED AS CRITERION D "EXCESSIVE IMPLEMENTATION COST")

SAMA ID Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements 1 CB-06 Locate RHR inside containment A

It is unlikely that a single RHR train could be placed within a Mark II primary containment. To locate all low pressure ECCS trains within containment to avoid ISLOCA events would not be possible. Therefore, the screening criterion for this SAMA candidate is changed to A - Not Applicable. This SAMA candidate is not considered for further evaluation.

CB-07 Ensure ISLOCA releases are E

SAMA candidate CB-01 evaluated the complete elimination of the ISLOCA scrubbed. One method is to plug scenarios and yielded a Phase 2 cost-benefit of approximately $46,800 (including drains in potential break areas so uncertainty). This is less than the cost of a small design change at CGS that break point will be covered

($100,000). Therefore, the screening criterion for this SAMA candidate is with water.

changed to E - Very Low Benefit. This SAMA candidate is not considered for further evaluation.

CP-06 Install a passive drywell spray D

A completely passive drywell spray system is not possible; however a design that system.

uses the containment vacuum breaker concept in reverse with a pressurized water tank of sufficient volume is conceptualized for cost implementation for this SAMA candidate. The existing drywell vent system or the drywell spray piping from RHR would be modified to allow an interfacing pre-charged water supply.

The water volume would need to be sufficient to spray the drywell over a reasonably long period of time. Additionally, the head pressure would need to be able to overcome the maximum drywell pressure up to the containment limit. A large water tank at an elevation 300-400 feet above the drywell would be required. Tower construction is unlikely due the height required. The nearest natural elevation is an elevated bluff across the Columbia River approximately 4 miles from the site. A CGS cost estimate for this SAMA candidate is greater than

$15,000,000. The cost of implementing a similar SAMA candidate at Vermont Yankee was estimated by Entergy Nuclear to require more than $5,800,000 in 2007. Assuming a 2% interest rate, the cost to implement would be $6,150,000 in 2010 dollars. The cost associated with the implementation of this SAMA candidate exceeds the maximum attainable uncertainty benefit. Therefore, this SAMA candidate is not considered for further evaluation.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 95 of 173 Table A-15: QUALITATIVE SCREENING OF SAMA CANDIDATES (ORIGINALLY SCREENED AS CRITERION D "EXCESSIVE IMPLEMENTATION COST")

SAMA ID Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements 1 CP-12 Install a filtered containment vent D

The conceptual design would be similar to AT-10 with the addition of a tank to remove decay heat.

capable of sustaining an internal pressure similar to the containment maximum Option 1: Gravel Bed Filter, pressures. This is required to serve as an expansion tank prior to release Option 2: Multiple Venturi Scrubber through a passive filtered means. It is assumed that the release has been scrubbed by the wetwell prior to this SAMA candidate final filtering through either Option 1 or 2., The cost would be similar to AT-10 except that the tank size would be smaller reducing its estimated cost. A CGS cost estimate for this SAMA candidate is' approximately $11,000,000. The cost associated with the implementation of this SAMA candidate exceeds the maximum attainable uncertainty benefit. Therefore, this SAMA candidate is not considered for further evaluation.

CP-1 3 Enhance FP system and SGT D

Although the CGS Reactor Building design is such that the roof serves as a relief system hardware and procedures point, the pressure spike from a large ruptured containment could challenge the ability to maintain the integrity of the upper Reactor Building walls. Strengthening the walls could be necessary to have measurable effectiveness of a FP spray or an enhanced SGT system. A SAMA case was performed in which the node for mitigation failure of a release to the Reactor Building was set to 1.OE-02. The resulting RRW was 1.000 as there is no CDF benefit for this type of SAMA candidate. Reductions in release categories form the bases for the benefits.

Estimated Phase 2 benefit from Cooper and Vermont Yankee yielded moderate benefits from approximately to $141,000 to $942,000 and from $1,410,000 to

$2,026,000 when the 9 5 th percentile for uncertainty is applied. The benefit results for CGS are expected to be within the range of Cooper's and Vermont Yankee's calculated cost-benefit. The estimated cost for implementing this SAMA was estimated by CGS to be much greater than $21,000,000 based on the cost for replacing the siding on the CGS Reactor Building in 2009. Therefore, this SAMA candidate is not considered for further evaluation.

CP-1 9 Create a large concrete crucible D

The cost of implementing a similar SAMA candidate at Vermont Yankee was with heat removal potential to estimated by Entergy Nuclear to require more than $100,000,000 in 2007. The contain molten core debris, cost associated with the implementation of this SAMA candidate exceeds the maximum attainable uncertainty benefit. Therefore, this SAMA candidate is not considered for further evaluation.

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SAMA ID Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements CP-20 Create a core melt source D

This SAMA candidate is similar to SAMA candidate CP-06 to install a passive reduction system.

drywell spray system except that a larger volume of water would be necessary to achieve containment flood-up and core melt debris mitigation quickly upon detection of vessel reaching its breaching point. The cost for CP-20 would be amplified by a larger passive flooding system of similar but larger volume design.

The flooding design would most likely use a lower drywell vent path to introduce the water directly to the lower portion of the drywell. This design would require consideration of steam explosion potential and the potential use of alternate fluid.

A CGS estimate for this SAMA candidate is approximately $24,000,000 based on scaling up the cost estimate for CP-06. The cost associated with the implementation of this SAMA candidate exceeds the maximum attainable uncertainty benefit. Therefore, this SAMA candidate is not considered for further evaluation.

CP-21 Strengthen primary/secondary D

The cost of implementing a similar SAMA candidate at Vermont Yankee was containment (e.g., add ribbing to estimated by Entergy Nuclear to require more than $12,000,000 in 2007. The containment shell).

cost associated with the implementation of this SAMA candidate exceeds the maximum attainable uncertainty benefit. Therefore, this SAMA candidate is not considered for further evaluation.

CP-22 Increase depth of the concrete D

Increasing the depth of the containment base mat is a difficult engineering feat for base mat or use an alternate an operating plant. The concept would be to tunnel under existing buildings (DG concrete material to ensure melt-Building and pump room areas of the Reactor Building and into the area directly through does not occur.

underneath the suppression pool) and excavate in sections. The placement of rebar and concrete would be similar to that for underground weapons defense sites or fuel storage project like Yucca Mountain. Recomposing the Class 1 soil would be required upon tunnel excavating. A CGS cost estimate for this SAMA candidate is approximately $35,000,000. The cost associated with the implementation of this SAMA candidate exceeds the maximum attainable uncertainty benefit. Therefore, this SAMA candidate is not considered for further evaluation.

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SAMA I Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements 1 CP-23 Provide a reactor vessel exterior D

This SAMA candidate is similar in design concept to CP-20 in that it assumes the cooling system.

ability to submerge the bottom of the reactor vessel head with cool water to prevent a vessel breach that potentially could expel molten core. Likewise its implementation costs would be similar, but the total volume of water injection could be less. Scaling down the cost estimated of CP-20 results in an estimated cost of approximately $17,000,000 for this SAMA candidate. The cost associated with the implementation of this SAMA candidate exceeds the maximum attainable uncertainty benefit. Therefore, this SAMA candidate is not considered for further evaluation.

CP-24 Construct a building to be D

The free volume space in the secondary containment is approximately 3.5E06 connected to primary/secondary cubic feet. Constructing a building of this size would be space and cost containment and maintained at a prohibitive at CGS. However, it would be possible to design a building or large

vacuum, tank that could maintain 1" vacuum or more of negative pressure similar to the condenser. A structure the size and capability of the condenser hotwell, which is maintained at 1 inch or more negative pressure by mechanical air ejectors backed by a 480 VAC commercial diesel, and connecting pipe from the Reactor Building is estimated to cost approximately $11,000,000. The cost associated with the implementation of this SAMA candidate exceeds the maximum attainable uncertainty benefit. Therefore, this SAMA candidate is not considered for further evaluation.

CP-29 Erect a barrier that would provide D

Significant modifications to the primary containment, if possible, are considered enhanced protection of the prohibitively expensive. The design would require adding ribbing to the containment walls (shell) from containment shell and a material barrier with characteristics sufficient to ejected core debris following a core withstand the molten debris. The cost of this SAMA candidate at Quad Cities melt scenario at high pressure.

was estimated to be $12,000,000. The cost associated with the implementation of this SAMA candidate exceeds the maximum attainable uncertainty benefit.

Therefore, this SAMA candidate is not considered for further evaluation.

1 The attainable uncertainty benefit for all SAMA candidates is derived from the uncertainty factor comprised from the ratio of the 9 5 th percentile to the mean point estimate of the baseline Integrated PSA Model Rev. 7.1 for the Internal Events, Fire, and Seismic hazards. Additionally, the Internal Events maximum uncertainty benefit value is added to the RRW benefit value to conservatively account for other external events benefit.

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SAMA ID Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements 1 AC/DC-05 Provide DC bus cross-ties E

With the ability to provide alternate power to DC buses from DG-3 or DG-4, this SAMA candidate provides little risk reduction. The CDF and LERF RRW values associated with making the cross-ties between divisional DC power sources always available are 1.021 and 1.0002, respectively (affects all hazards, but primarily Fire), and the estimated uncertainty benefit based on RRW is approximately $180,000. This benefit represents two cross-ties: one between Division 1 and 2 and the other between Division 1 or 2 to Division 3. Note:

Division 3 is not of sufficient size to backfeed Division 1 or 2 loads. The individual cross-tie benefit would be about one half of the estimated benefit for this SAMA candidate, which is below the cost for a small design change at CGS

($100,000). Therefore, this SAMA candidate is not considered for further evaluation.

AC/DC-06 Provide additional DC power to the 120/240V vital AC system E

120/240V AC is not risk significant at CGS. The CDF and LERF RRW values associated with making the buses perfect are 1.002 and 1.000, respectively (affects primarily Fire). The estimated uncertainty benefit based on RRW is less than $15,000, which is below the cost for a small design change at CGS.

Therefore, this SAMA candidate is determined to have a very low benefit and is not considered for further evaluation.

AC/DC-08 Increase training on a response to a loss of two 120V AC buses that cause inadvertent actuation signals t:

120/240V AC is not risk significant at CGS. The estimated uncertainty benefit based on RRW associated with AC/DC-06 provides a very small benefit when making the120V AC sources perfect. Abnormal procedures currently exist at CGS for loss of 120V AC, which contain detailed information on lost indication and specific restoration actions. The operators receive periodic operator training on these procedures. Improving operator response associated with the loss of a 120V AC bus would not be likely to yield a SAMA candidate with real benefit.

Therefore, this SAMA candidate is determined to have a very low benefit and will not be considered for further evaluation.

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SAMA ID Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements' AC/DC-21 Use fire water system as a backup source for diesel cooling E

The DG cooling water source is SW. This SAMA candidate only addresses loss of SW to the DG and not to other equipment (since this SAMA candidate is attempting to increase DG availability.) The CDF and LERF RRW values associated with doubling the DG cooling reliability are 1.005 and 1.000, respectively (affects primarily Fire). The estimated uncertainty benefit based on RRW is less than $70,000, which is below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

AC/DC-22 Add a new backup source of diesel cooling AT-04 Increase boron concentration in the SLC system This SAMA candidate is similar in intent to AC/DC-21. The RRW associated with doubling the DG cooling reliability calculated for AC/DC-21 also applies to this SAMA candidate, and the estimated uncertainty benefit is below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

A change to the CGS Technical Specifications has been submitted to the NRC for increasing the SLC boron concentration (i.e., use of boron enriched in the isotope B-10). This TS change achieves the intent of this SAMA candidate.

Therefore, the screening criterion for this SAMA candidate is changed to Criterion B - Already Implemented.

CB-02 Add redundant and diverse limit switches on each CIV c E

Isolation at CGS is considered quite reliable. CGS CIVs that only provide a containment isolation function (V-Sequence related) are air-operated. The CDF and LERF RRW values associated with eliminating containment isolation failures (except pre-existing and flooding) and reducing ISLOCA failures by one half are 1.002 and 1.018, respectively (primarily Internal Events LERF), and the estimated uncertainty benefit based on RRW is approximately $260,000. The uncertainty benefit for one MS line penetration improvement (modification of two MSIVs) would be approximately $65,000, which is below the cost of a small design change. If the benefit is further reduced to a per-valve basis for the other CIVs, this SAMA candidate is of very low benefit. Therefore, this SAMA candidate is not considered for further evaluation.

I _______

I

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Modification Revised Basis for Screening/

SAMA ID (Potential Enhancement)

Criteria Modification Enhancements1 CB-05 Install self-actuating CIVs E

Containment isolation at CGS is considered very reliable. CGS CIVs that are normally open and have a containment isolation function are air-operated and are self-actuating. The estimated uncertainty benefit based on RRW that was calculated for SAMA candidate CB-02 ($260,000) also applies to this SAMA candidate. The modification of the ECCS, RWCI and RCC penetration pathways involve seven lines and the conversion of fourteen MOVs. (The MS lines and containment atmosphere lines have air-operated self-actuating CIVs.) The estimated uncertainty benefit based on RRW of each line would be approximately

$35,000, which is below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

CC-08 Modify ADS components to E

The ADS at CGS is very reliable and not risk significant. The CDF and LERF improve reliability RRW values associated with doubling the ADS valves' reliability are calculated to both be 1.000, indicating no risk improvement, and the estimated uncertainty benefit is well below the cost for a small design change at. CGS. Therefore, this SAMA candidate is not considered for further evaluation.

CC-09 Add signals to open SRVs E

For an MSIV closure event, one or more SRVs may open briefly. Opening of automatically in an MSIV closure SRVs is very reliable and not a significant contributor to risk. The CDF and LERF transient RRW values associated with making the SRV pressure relief function perfect are 1.0041 and 1.000, respectively (affects Internal Events only), and the estimated uncertainty benefit based on RRW is less than $10,000, which is well below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

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SAMA ID Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements 1 CC-12 Add a diverse low pressure D

CGS has significant redundancy of low pressure systems; thus these systems injection system have low to moderate risk significance. The CDF and LERF RRW values associated with reducing the unavailability of the low pressure ECCS injection function by 3 orders of magnitude are 1.046 and 1.007, respectively (affects Internal Events and Fire), and the estimated uncertainty benefit based on RRW is approximately $1,000,000. The implementation cost for this SAMA was evaluated by Vermont Yankee to be greater than $3,900,000. With the significant difference in estimated RRW uncertainty benefit and the implementation cost, the screening criterion for this SAMA candidate is changed to D - Excessive Implementation Cost. This SAMA candidate is not considered for further evaluation.

CC-13 Increase flowrate of suppression E

The increase in flowrate for CGS adds little benefit. Cooling is provided by RHR pool cooling Trains A and B. Once SPC is activated, additional cooling will not provide additional mitigating benefit. Significant time currently exists for this operator action. However, a potential benefit to ATWS sequences is to provide additional operator time to place SLC in service. The CDF and LERF RRW values associated with making the operator action perfect for initiating SLC during an MSIV closure ATWS are 1.001 and 1.007, respectively. The estimated uncertainty benefit based on RRW is approximately $110,000. Modification of both RHR Trains A and B pump impellers, increasing the horsepower of the pump motors and redesigning the distribution system would be required to achieve this benefit. The estimated uncertainty benefit based on RRW for each RHR train is approximately $55,000, which is below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

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SAMA ID Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements 1 CC-15 Provide capability for alternate E

RWCU has no source of water other than the RPV. It receives cooling from TSW.

injection via RWCU Therefore, if other sources of injection are unavailable, it is likely that RCWU will also be unavailable. The CDF and LERF RRW values associated with making an alternate injection system more reliable by a factor of 2 are 1.006 and 1.000, respectively (affects primarily Internal Events). The estimated uncertainty benefit based on RRW is approximately $40,000, which is below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

CC-23 Replace two of the four electric D

CGS has ample diversity of coolant injection systems that have multiple offsite safety injection pumps with diesel-power supplies and are backed up by independent diesels. The modeling powered pumps approach for SAMA candidate CC-12, reducing the unavailability of low pressure ECCS injection, bounds this SAMA candidate. SAMA candidate CC-23 adds diversity to the existing injection systems. However the improvement in CCF provided by this SAMA candidate would not reach the improvement of an additional coolant injection system proposed by SAMA candidate CC-12.

Additionally, diesel-driven injection pumps most likely will require a separate building and piping to the reactor since the pump rooms at CGS are not compatible with diesel-driven pumps which could introduce additional fire risks that offset improvement in diversity. The implementation cost exceeds the implementation costs of SAMA candidate CC-12 since separate structures would be required for divisional separation. With the significant difference in estimated RRW uncertainty benefit and the implementation cost of SAMA candidate CC-12, an even larger difference would occur with this SAMA candidate. Therefore, the screening criterion for this SAMA candidate is changed to D - Excessive Implementation Cost. This SAMA candidate is not considered for further evaluation.

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SAMA I Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements 1 CP-04 Enable flooding of the drywell head D

For containment overpressure or over-temperature, failure at four locations is seal considered credible for scenarios that do not result in effective pool or spray scrubbing. Three of the locations: 1) upper cylinder-cone junction, 2) equipment hatch, and 3) wetwell above the water line are all considered the most likely failure points with equal probability. The drywell head, although possible, is considered less likely. The RRW associated with loss of injection caused by containment failure was reduced to zero to assess this SAMA candidate's benefit. This modeling is very conservative in that loss of injection is primarily driven by failure sites much lower in the containment that would not be improved by this SAMA candidate. The calculated CDF and LERF RRW values are both 1.126 (affects all hazards), and the estimated uncertainty benefit based on RRW is approximately $500,000. A cost-benefit analysis performed by Vermont Yankee produced a much lower benefit through a Phase 2 analysis which also included the uncertainty factor. Vermont Yankee reported a cost for implementation of greater than $1,000,000. Similar results would occur for CGS, and this SAMA would not be cost-beneficial. Therefore, the screening criterion for this SAMA candidate is changed to D - Excessive Implementation Cost. This SAMA candidate is not considered for further evaluation.

CP-08 Enhance procedures to refill CST E

CST level is a Technical Specification parameter that requires action to refill the from demineralized water or SW CST within a limited time period. The SAMA candidate assumes that sufficient system volume is not available and that a refill would provide additional volume for injection. Only HPCS and RCIC take suction from the CST for accident mitigation purposes. Therefore, this SAMA candidate would only support sequences that require high pressure injection (i.e. loss of depressurization capability). Additionally, CGS has two full capacity CSTs and additional make-up would not add significant risk improvement. The model was modified to provide an unavailability of one CST at 1.OE-04 assuming that sufficient inventory was not available and one CST would be required to-be refilled to support high pressure injection risk mitigation. The CDF and LERF RRW values associated with this condition are 1.001 and 1.000, respectively (Internal Events). The estimated uncertainty benefit based on RRW is below $1000, which is well below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

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SAMA ID Modification Revised Basis for Screening!

(Potential Enhancement)

Criteria Modification Enhancements 1 CP-09 Enhance procedures to maintain B

RCIC and HPCS are the only ECCS pumps that can take suction from the CST.

ECCS suction on CST as long as Specific guidance is included in operating procedures for both RCIC and HPCS possible to avoid low water level conditions in CST or suppression pool lineups to avoid conditions that potentially could result in loss of NPSH. During events when containment venting is necessary, the suppression pool level will lower, resulting in lower NPSH for the HPCS and RCIC pumps. However, the level does not lower enough to cause the pumps to lose NPSH within the pumps' 24-hour mission time. Vortex limits, in terms of suppression pool level, are clearly indicated in procedures. The vortex limits are low relative to normal suppression pool level (5.5' and 17.5', respectively, for HPCS and RCIC relative to the -30' normal level). Therefore, the screening criteria of this SAMA candidate is changed to Criterion B - Already Implemented.

CP-1 1 Install an unfiltered hardened D

A sensitivity study performed as part of the CGS IPE concluded that a hardened containment vent vent would not significantly reduce off-site releases following core damage.

Venting currently is an option for decay heat removal following loss of SPC. A SAMA case was performed in which the containment vent unavailability was low (1.OE-09) and free from fire damage. The resulting integrated model CDF and LERF RRW values are 1.275 and 1.000, respectively (affects Internal Events and Fire). The estimated uncertainty benefit based on RRW is approximately

$1,500,000, which is higher than cost-benefit Phase 2 cost-benefit results reported by other BWRs. Estimates of installation cost from other BWRs range from greater than $2,500,000 to greater than $5,000,000. An actual cost for the existing hardened pipe vent at Hope Creek installed in 1993 was between

$5,000,000 and $6,000,000. A CGS cost estimate is $6,850,000, which is similar to the Hope Creek estimate adjusted for inflation. This SAMA candidate would not be cost-beneficial for CGS. Therefore, the screening criterion for this SAMA is changed to D - Excessive Implementation Cost. This SAMA is not considered for further evaluation.

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SAMA I Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements 1 CP-17 Improve wetwell to drywell vacuum B

The wetwell-to-drywell vacuum breakers are dual seat: each relief valve breaker reliability by installing assembly consists of two discs with two seats, which operate independently.

redundant valves in each line Each valve disc is equipped with a positive closure mechanism, a magnetic latch, an exercising mechanism, and redundant limit switches. Therefore, the screening criterion for this SAMA candidate is changed to Criterion B - Already Implemented.

CP-18 Provide post-accident containment E

The CGS containment is inert at power conditions. The PSA quantifies hydrogen inerting capability combustion as 5.OE-03. The CDF and LERF RRW values associated with making the probability for de-inerting or oxygen introduction equal to zero are both 1.000. There is no estimated uncertainty benefit for CGS. Therefore, this SAMA candidate is not considered for further evaluation.

CP-26 Improve leak detection procedures Subsumed The Control Building area was identified for additional leak detection by FL-05R, improvement by the Integrated PSA Model Rev. 7.1. SAMA candidates FL-05R, FL-04R, FL-06R FL-04R, and FL-06R address this area of improvement and are evaluated for cost-benefit. These SAMA candidates replace SAMA candidate CP-26.

CP-27 Install independent power supply to A

CGS has a Mark II containment and does not have a hydrogen control system.

the hydrogen control system using The CGS containment is inerted at power conditions. As such, the screening either new batteries, a non-safety criterion for this SAMA candidate is changed to A - Not Applicable to CGS.

grade portable generator, existing station batteries, or existing AC/DC independent power supplies, such as the security system diesel.

CW-08 Enhance the screen wash system E

The SW ponds at CGS are a semi-closed system and screen clogging is highly unlikely. Also, the screens are excessively oversized for the SW flow rates. The CDF and LERF RRW values associated with reducing the SW screens' unavailability by a factor of two are 1.009 and 1.0002, respectively (affects Internal Events and Fire). The estimated uncertainty benefit based on RRW is approximately $70,000, which is below the cost for a small design change at CGS Therefore, this SAMA candidate is not considered for further evaluation

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SAMA ID Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements 1 FR-01 Replace mercury switches in FP B

The original diesel fire pump controllers were designed with mercury switches.

system The diesel fire pump controllers have been evaluated and are approved as part of the CGS obsolescence program. One diesel fire pump controller remains to be replaced as part of this existing program. Therefore, the screening criterion for this SAMA candidate is changed to Criterion B - Already Implemented. This SAMA candidate is not considered for further evaluation.

FR-02 Upgrade fire compartment barriers E

The CGS IPEEE conclusions cited no weaknesses in compartment fire barriers that contributed to any significant risk.. A potential SAMA candidate associated with providing fire'barriers for the two oil-filled transformers in each of the critical switchgear rooms was identified. Although a portion of the 480V distribution would be lost due to the transformer failure, the protected switchgear, the other 480V oil-filled transformer, and other components in the division would still receive power. Special HVAC cooling and ducting is also required to preserve the effectiveness of the fire barrier and to provide adequate transformer cooling.

This SAMA candidate was modeled by setting the accident sequences involving ignition of oil-filled transformer fires in switchgear rooms to zero. The CDF and LERF RRW values for addition of four fire barriers to separate each of the oil filed transformers from the switchgear, inverter, and other electrical panels in both the Division 1 and Division 2 electrical switchgear rooms are 1.034 and 1.0003, respectively (affects Fire only). The estimated uncertainty benefit based on RRW is $180,000. The estimated uncertainty benefit per transformer is roughly

$45,000, which is below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

FW-03 Install an independent diesel for E

CGS has the ability to connect the diesel driven fire water pump to the suction of the CST makeup pumps a condensate booster pump for RPV makeup. The CDF RRW associated with making the uncertainty of one CST very low (see SAMA candidate CP-08) is 1.001 (affects Internal Events, no LERF contribution). The estimated uncertainty based on the RRW value of SAMA candidate CP-08 represents the uncertainty benefit expected of this SAMA candidate and is well below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

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Modification Revised Basis for Screening/

SAMA ID (Potential Enhancement)

Criteria Modification Enhancements 1 FW-04 Add a motor-driven FW pump C

SAMA Candidate FW-04 is evaluated for cost-benefit using the Integrated PSA Model Rev. 7.1. The screening criterion was revised to Criterion C - Considered for Further Evaluation.

HV-05 Create ability to switch HPCS and E

This SAMA candidate is intended to increase the availability of RCIC and high RCIC room fan power supply to DC pressure coolant injection in an SBO event. The need for RCIC fan cooling in an SBO event during an SBO has already been analyzed and found to not be required. The other high pressure injection pump at CGS is a motor driven pump (HPCS).

HPCS fan cooling ýis supplied during an SBO by its own diesel and separate electrical divisioni In the event that the power is lost only to the fan, operators can open doors tothe HPCS pump room for alternate room cooling until the cause can be corrected. The CDF and LERF RRW values associated with providing a batter-vacked inverter supply to the HPCS fan are both 1.0000 indicating the RRW value is not sufficiently high enough to generate a benefit value. Therefore, this SAMA candidate is not considered for further evaluation.

HV-06 Enhance procedures to trip A

Each ECCS pump is located in a separate room. Each room has a room cooler unneeded RHR or core spray with fans powered from the associated division and cooling water supplied by the pumps on loss of room ventilation respective division of SW.- Failures of the HVAC in one ECCS subsystem would not impact the operability of the other subsystem within the division or redundant trains in the other divisions. Therefore, the criterion for this SAMA is changed to A - Not Applicable. This SAMA candidate is not considered for further evaluation.

IA-02 Modify procedure to provide ability E

Two of three CAS compressors are backed up by DGs. The only safety-related to align diesel power to more air components supplied directly from CAS are the outboard MSIV solenoids. CAS compressors is backup for inboard MSIVs and SRVs. On a LOOP, opening of the MSIVs is not an option since the BOP systems are unavailable. The CDF and LERF RRW values associated with making the CAS system perfectly reliable are 1.002 for both. To implement this SAMA candidate, the third CAS compressor would require the installation of a manual transfer switch to transfer the power from the diesel-backed compressor to the third compressor assuming the first compressor failed. The estimated uncertainty benefit based on RRW is approximately

$20,000, which is below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

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SAMA ID Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements 1 IA-03 Replace service and instrument air E

The CAS compressors are cooled by the TSW system, which is backed up by the compressors with more DGs. In the event that TSW fails, the compressors can be cooled by fire water.

compressors that have self-The CDF and LERF RRW values associated with removing the TSW dependency contained air cooling by shaft are 1.000 and 1.001, respectively. The estimated uncertainty benefit based on driven fans RRW is less than $5,000, which is below the cost for a procedure change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

IA-05 Improve SRV and MSIV pneumatic E

SRVs and MSIVs are very reliable and further improvement would not contribute components significantly to plant risk. The CDF and LERF RRW values associated with reducing the unavailability of SRV, MSIV, pneumatic components by a factor of 2 are 1.001 and 1.0003, respectively. The estimated uncertainty benefit based on RRW is approximately $15,000, which is below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

OT-01 Install digital large break LOCA E

LLOCA is not a large risk contributor at CGS, and this modification is not protection system considered to significantly reduce the risk of a LLOCA. The CDF and LERF RRW values associated with making the probability of a LLOCA very low (5.0E-10) are both 1.0001. The estimated uncertainty benefit based on RRW is less than

$1,000, which is below the cost for a small design change at CGS. Therefore, this SAMA candidate is not considered for further evaluation.

OT-02 Enhance procedures to mitigate E

Large break LOCAs are dominated by automatic initiation of mitigating systems.

large break LOCA SAMA Candidate OT-01 addresses making the probability of a LLOCA very small. Operator actions associated with a LLOCA would be similarly very low benefit. Therefore, this SAMA is not considered for further evaluation.

OT-04 Improve maintenance procedures Subsumed This SAMA is subsumed by SAMA candidate OT-07R which is evaluated for by OT-07R cost-benefit. Improvement to maintenance procedures has been added as an attribute of SAMA candidate OT-07R.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 109 of 173 Table A-16: QUALITATIVE SCREENING OF SAMA CANDIDATES (ORIGINALLY SCREENED AS CRITERION E "VERY LOW BENEFIT")

SAMA ID Modification Revised Basis for Screening/

(Potential Enhancement)

Criteria Modification Enhancements1 OT-05 Increase training and operating B

Plant training or feedback issues are identified and their significance to plant risk experience feedback to improve assessed through the Operating Experience program. Improvement in this operator response program is an ongoing element within the CGS process. This program is effective and receives continual management oversight and emphasis.

Therefore, the screening criterion for this SAMA candidate is changed to B -

Already Implemented. This SAMA candidate is not considered for further evaluation.

SR-01 Increase seismic ruggedness of D

The CDF and LERF RRW values associated with reducing the seismic failure for standby SW pumps and RHR heat RHR heat exchangers and SW pumps to zero for the seismic sequence exchangers SDS41 S01 are 1.032 and 1.0000, respectively (affects Seismic only). This sequence contributes 87% of the seismic CDF - 35% of which is related to the RHR system and 65% to the SW system. The estimated uncertainty benefit of making the RHR and SW components impervious to seismic failure (before Reactor Building collapse) based on RRW is approximately $380,000. Increasing the seismic ruggedness of the RHR pumps, heat exchangers, and piping would also be necessary. The work on the heat exchangers and their piping would be in a high radiation area, which complicates this modification. For the benefit to be realized, both SW systems would be required to be modified. A CGS cost estimate is approximately $10,000,000. This SAMA candidate would not be cost-beneficial for CGS. Therefore, the screening criterion for this SAMA candidate is changed to D - Excessive Implementation Cost. This SAMA candidate is not considered for further evaluation.

'Where RRW benefit values are provided, the value listed represents the SAMA candidate's combined RRW value from Internal Events, Fire and Seismic Level 1 and Level 2 (CDF and LERF). To calculate the candidate's estimated uncertainty benefit based on RRW, the formula provided in Section 3.1 is used to derive an estimated benefit for each hazard based on the SAMA candidate's RRW for that hazard and then it is multiplied by the uncertainty factor associated with the PSA hazard provided in Section 4.1. All hazards with a benefit are summed. This is duplicated for determining the estimated uncertainty benefit associated with LERF. Conservatively, CDF and LERF RRWs use the same formula from Section 3.1, potentially doubling the SAMA candidate's estimated uncertainty value based on RRW. The uncertainty benefit from the CDF and LERF based on RRW are then summed.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 110 of 173 APPENDIX B COST-BENEFIT RESULTS FROM REV. 7.1 OF THE PSA Table B-1 Table B-2 Table B-3 Table B-4 Table B-5 Table B-6 Table B-7 Table B-8 Summary of PSA Cases Internal Events Benefit Results Fire Benefit Results Seismic Benefit Results Total Benefit Results Implementation Cost Estimates Final Result of the Cost-benefit Evaluation Total Benefit Results for the Sensitivity Cases

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 111 of 173 Table B-i: Summary of PSA Cases' Total SAMA Risk Reduction CDF (1/yr)

CDF Candidate Description Model Approach (l/yr)

Internal Fire Seismic Maximum benefit.

7.50E-06 1.37E-05 4.86E-06 2.61E-05 AC/DC-01 Provide additional DC battery Period for off-site/onsite recovery of power 7.46E-06 1.37E-05 4.86E-06 2.60E-05 capacity.

extended to 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> during SBO when RCIC successfully starts and runs on dc power.

AC/DC-02 Replace lead-acid batteries Period for off-site / onsite recovery of 7.46E-06 1.37E-05 4.86E-06 2.60E-05 with fuel cells.

power extended to 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> during SBO when RCIC successfully starts and runs on dc power.

AC/DC-03 Add a portable, diesel-driven Period for off-site / onsite recovery of 7.46E-06 1.37E-05 4.86E-06 2.60E-05 battery charger to existing DC power extended to 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> during SBO system.

when RCIC successfully starts and runs on dc power.

AC/DC-10 Provide an additional DG.

DG-1 was selected due to RCIC 7.37E-06 1.24E-05 4.83E-06 2.46E-05 dependency on DG-1. Gate GlAC544 was set to a low value.

AC/DC-1 5 Install a gas turbine DG-1 was selected due to RCIC 7.37E-06 1.24E-05 4.83E-06 2.46E-05 generator.

dependency on DG-1. Gate G1AC544 was set to a low value.

AC/DC-16 Install tornado protection on DG-1 was selected due to RCIC 7.37E-06 1.24E-05 4.83E-06 2.46E-05 gas turbine generator.

dependency on DG-1. Gate GlAC544 was set to a low value.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 112 of 173 Table B-i: Summary of PSA Cases' Total SAMA Risk Reduction CDF (1/yr)

CDF Candidate Description Model Approach (1/yr)

Internal Fire Seismic AC/DC-23 Develop procedures to repair BED data will be changed as noted in 7.09E-06 1.35E-05 4.86E-06 2.55E-05 or replace failed 4 kV attached spreadsheet (4 kV AC breakers breakers. In the event of a tab).

loss of bus due to a failed breaker, this SAMA candidate would provide the ability to repair or replace 4 kV breakers in a timely manner to restore AC power to the affected division.

AC/DC-27 Install permanent hardware An unavailability of 1 E-02 is assumed for 6.73E-06 8.50E-06 4.86E-06 2.01 E-05 changes that make it possible the 500 kV backfeed basic event: EAC----

to establish 500 kV backfeed 500KVFEED. Assumed to not be through the main step-up available for seismic analysis. For the fire transformer.

analysis, EAC ---- 500KVFEED is conservatively assumed to be fire-protected (maximum risk benefit).

AC/DC-28 Reduce CCFs between DG-3 Combinations of DG-1 and DG-3 as well 7.47E-06 1.36E-05 4.86E-06 2.59E-05 and DG-1/2.

as DG-2 and DG-3 were reduced, in addition to CCF of all three. The values were reduced by a factor of 2.

AC/DC-29 Replace DG-3 with a diesel Only the CCFs for DG-1 and DG-2 7.44E-06 1.34E-05 4.86E-06 2.57E-05 diverse from DG-1 and DG-2.

common cause group of two will be used.

All others will be set to zero.

AT-05 Add an independent boron C(3) functions set to a low value (1 E-09) 7.36E-06 1.37E-05 4.86E-06 2.59E-05 injection system.

for Internal Events. For Seismic, damage state 40 (SDS40) is set to zero. No change to the FPSA results (ATWS sequences associated with fire are not risk significant and are not modeled by the PSA).

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 113 of 173 Table B-i: Summary of PSA Cases1 Total SAMA Risk Reduction CDF (1/yr)

CDF Candidate Description Model Approach (1/yr)

Internal Fire Seismic AT-07 Add a system of relief valves SRV failures set to zero, including failure 7.50E-06 1.37E-05 4.86E-06 2.61 E-05 to prevent equipment damage of one valve when 7 of 7 ADS valves must from pressure spikes during open. There was no change in CDF. The an ATWS.

SRV failures have no risk importance due to the high likelihood for success of the function.

CB-01 Install additional pressure or ISLOCA contribution to PSA results 7.39E-06 1.37E-05 4.86E-06 2.60E-05 leak monitoring instruments (Internal Events) will be removed.

for detection of interfacing system loss of coolant accidents (ISLOCAs).

CB-03 Increase leak testing of ISLOCA contribution to PSA results 7.39E-06 1.37E-05 4.86E-06 2.60E-05 valves in ISLOCA paths.

(Internal Events) will be removed.

CB-08 Revise EOPs to improve ISLOCA contribution to PSA results 7.39E-06 1.37E-05 4.86E-06 2.60E-05 ISLOCA identification.

(Internal Events) will be removed.

CB-09 Improve operator training on ISLOCA contribution to PSA results 7.39E-06 1.37E-05 4.86E-06 2.60E-05 ISLOCA coping.

(Internal Events) will be removed.

CC-01 Install an independent active HPCS event tree functions set to a low 3.01 E-06 3.55E-06 4.74E-06 1.13E-05 or passive high pressure value (1 E-09).

injection system.

CC-02 Provide an additional high HPCS event tree functions set to a low 3.01 E-06 3.55E-06 4.74E-06 1.13E-05 pressure injection pump with value (1 E-09).

independent diesel.

CC-03b Raise RCIC backpressure trip The various RCIC failure to run events are 7.49E-06 1.37E-05 4.86E-06 2.61 E-05 set points.

reduced by a factor of 3.

CC-20 Improve ECCS suction ECCS suction strainer plugging events set 7.45E-06 1.37E-05 4.86E-06 2.60E-05 strainers, to zero.

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CDF Candidate Description Model Approach (l/yr)

Internal Fire Seismic CP-01 Install an independent The W(1) functions (SPC) were modeled 5.01 E-06 6.36E-06 4.82E-06 1.62E-05 method of SPC.

as perfectly reliable. Operator action to align W(1) assumed to be necessary.

CW-02 Add redundant DC control Control power dependencies associated 6.74E-06 1.30E-05 4.86E-06 2.46E-05 power for pumps.

with gates GHPS852, GRHR652, GRHR1552, GRHR3452, GLPS372, control power gates for RCIC were set to a low value.

CW-03 Replace ECCS pump motors Pump cooling dependencies modeled 7.30E-06 1.33E-05 4.86E-06 2.55E-05 with air-cooled motors.

under GRHR520, GRHR1420, GRHR3320 and GLPS402 set to a low value. No external pump cooling modeled for RCIC or HPCS, so no change for these pumps.

CW-04 Provide self-cooled ECCS Pump cooling dependencies modeled 7.30E-06 1.33E-05 4.86E-06 2.55E-05 seals.

under GRHR520, GRHR1420, GRHR3320 and GLPS402 set to a low value. No external pump cooling modeled for RCIC or HPCS, so no change for these pumps.

CW-07 Add a SW pump.

GSWB1 23, GXWB123, GYWB123 and 6.70E-06 1.20E-05 4.86E-06 2.36E-05 GZWB123 set to a low value.

I IIL

_I

SENSITIVITY STUDY. BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 115 of.173 Table B-i: Summary of PSA Cases' Total SAMA Risk Reduction CDF (1/yr)

CDF Candidate Description Model Approach (1/yr)

Internal Fire Seismic FR-03 Install additional transfer and Circuits downstream of the isolation 7.50E-06 1.29E-05 4.86E-06 2.53E-05 isolation switches.

switch/transfer switch will be susceptible to hot short/ spurious operation. Such switches, to be effective, would need to be installed very near the components in question.

The hot short probability was reduced to zero for the most risk significant hot shorts:

HS-EAC-TRS HS-CIAV-MO20 HS-CIAV-MO30A HS-ADS-OPEN HS-RHRV-MO-6B FR-07a Improve the fire resistance of Protect cables for containment vent 7.50E-06 9.60E-06 4.86E-06 2.20E-05 critical cables.

(valves, containment air and power supplies).

FR-07b Improve the fire resistance of Protect cables for that would disable TR-S 7.50E-06 1.33E-05 4.86E-06 2.57E-05 critical cables.

due to hot short.

HV-02 Provide a redundant train or GXWA1 112, GXWB1 112, GYWA1 112, 7.48E-06 1.37E-05 4.86E-06 2.60E-05 means of ventilation.

GYWB1 112, GZWA1 112, GZWB1 112 set to a low value.

SR-03 Modify safety related CST.

Basic events HPSV-CH ---- 2P2LL and 7.50E-06 1.37E-05 4.82E-06 2.60E-05 RCIV-CH--- 11 P2LL were removed from S-BASE.BED to credit CST availability.

AT-13 Automate SLC injection in Set SLCHUMN20MINH3XX and 7.46E-06 1.37E-05 4.86E-06 2.60E-05 response to ATWS event.

SLCHUMN40MINH3XX to zero.

AT-14 Diversify SLC explosive valve Set SLCV-SQ--4ABC2XX to zero.

7.50E-06 1.37E-05 4.86E-06 2.61 E-05 operation.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 116 of 173 Table B-i: Summary of PSA Cases' I

Total SAMA Risk Reduction CDF (1/yr)

CDF Candidate Description Model Approach (1/yr)

Internal Fire Seismic SR-05R Improve seismic ruggedness of MCC-7F and MCC-8F.

Given a seismic event, MCC-7F and MCC-8F are likely to fail whenever Division 3 electrical power fails, based on component fragilities. The loss of these MCCs causes loss of Division 1 and Division 2 switchgear room cooling. No credit is assigned for alternate ventilation of the switchgear rooms due to the occurrence of a seismic-LOCA (no credit is given.in the internal events PSA for alternate ventilation for LOCAs, due to the higher electrical heat loads), and potential challenges to obtain electrical power for portable fans, given a seismic event.

The model was modified to represent failing room cooling for Division 1 and Division 2 switchgear rooms for the seismic damage states indicated.

NOTE: The quantification result becomes the Base Case in the Phase 2 calculations for this candidate. The CDF produced from base case PSA then becomes the benefit case.

7.50E-06 1.37E-05 5.76E-06 2.70E-05

.6.

d b

S

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CDF Candidate Description Model Approach (l/yr)

Internal Fire Seismic OT-08R Install explosion protection Plant-centered LOOP and switchyard-7.39E-06 1.37E-05 4.86E-06 2.60E-05 around CGS transformers.

centered LOOP account for 37.2% of the The CGS startup transformer Columbia LOOP frequency (NUREG/CR-and backup transformer are 6890). Reduce the LOOP frequency by not in close proximity.

this amount. The LOOP frequency, TE However, there are the step was changed to 1.87E-02, which is a up main transformers and 37.2% reduction from the LOOP frequency auxiliary transformers that of 2.98E-02/ reactor-year.

separate them. Although CGS transformers are protected with sudden pressure relays to mitigate rapid pressure increases from resulting in explosion, should they fail, there is a possibility that missiles generated from a transformer explosion could impact other transformers and potentially their incoming associated power lines.

Although the cost for explosion protection is expected to be significantly greater than the maximum benefit, a SAMA case will be considered.

FL-05R Install three clamp-on flow The control building flood isolation HEPs 6.27E-06 1.37E-05 4.86E-06 2.48E-05 instruments to certain drain were reduced to 1 E-02 to represent the

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CDF Candidate Description Model Approach (1/yr)

Internal Fire Seismic lines in the Control Building improvement in operator timing response area of the Radwaste due to prompt flooding identification Building and alarm in the provided by the additional instrumentation.

Control Room. The new This list of HEPs consists of the following:

flooding sources do not have FP-HUMNIC205H3LL a means to detect a flood.

FP-HUMNIC304H3LL These flow instruments would SW-HUMN-W51 13LL alarm in the Control Room to alert operators that a large SW-HUMN-W521H3LL flow of water was coming SW-HUMN-W523H3LL from area drains. These SW-HUMN-W531H3LL drains are normally dry, so SW-HUMN-W532H3LL any alarm would be cause for SW-HUMNIC212H3LL immediate investigation.

SW-HUMNIC502H3LL SW-HUMNIC525H3LL TSWHUMNIC502H3LL TSWHUMNIC525H3LL XDPHUMN-W521 H3LL XDPHUMN-W523H3LL XDPHUMN-W532H3LL XDPHU MNIC502H3LL FL-04R Install one isolation valve in The Control Building flood isolation HEPs 6.26E-06 1.37E-05 4.86E-06 2.48E-05 each of the SW, TSW, and were reduced to represent the FP lines in the Control improvement in flooding isolation capability Building area of the by the addition of isolation valves in the Radwaste Building to piping branch lines that could result in

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CDF Candidate Description Model Approach (l/yr)

Internal Fire Seismic facilitate rapid isolation by the Control Building flooding. Specifically, the operators upon receipt of a Control Building flood isolation HEPs were high flow alarm.

reduced to 0.0:

FP-HUMNIC205H3LL FP-HUMNIC304H3LL SW-H UMN-W51 11H3LL SW-HUMN-W521 H3LL SW-HUMN-W523H3LL SW-HUMN-W531 H3LL SW-HUMN-W532H3LL SW-HUMNIC212H3LL SW-HUMNIC502H3LL SW-H UMNIC525H3LL TSWHUMNIC502H3LL TSWHUMNIC525H3LL XDPHUMN-W521 H3LL XDPHUMN-W523H3LL XDPHUMN-W532H3LL XDPHUMNIC502H3LL FL-06R Perform additional NDE and The increased testing intervals and 6.87E-06 1.37E-05 4.86E-06 2.54E-05 inspections to the three lines locations of critical piping in the Control identified in SAMA candidate Building are expected to improve detection FL-04R to verify that and timely corrective maintenance. To degradation is not occurring model this improvement, the control in these lines. The specific building flood isolation HEPs were reduced locations of the NDE would by a factor of 2 to represent early detection

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CDF Candidate Description Model Approach (l/yr)

Internal Fire Seismic be selected from potentially susceptible areas using similar methods as used in the risk-informed in-service inspection program to detect wall thinning.

of degrading piping. The specific HEPs are:

IE-FLD-C205-FP-U IE-FLD-C212SSWAU IE-FLD-C212SSWBU IE-FLD-C304-FP-U IE-FLD-C502SSWAU IE-FLD-C502SSWBU IE-FLD-C502TSW-U IE-FLD-C507SSWAM IE-FLD-C507SSWAS IE-FLD-C507SSWAU IE-FLD-C507TSW-M IE-FLD-C507TSW-S I E-FLD-C507TSW-U IE-FLD-C507WCH-S IE-FLD-C508SSWBM IE-FLD-C508SSWBS IE-FLD-C508SSWBU IE-FLD-C508TSW-M IE-FLD-C508TSW-S IE-FLD-C508TSW-U IE-FLD-C508WCH-S IE-FLD-W51ASSWAS IE-FLD-W52ASSWAS IE-FLD-W52ASSWAU I E-FLD-W52BSSWBS IE-FLD-W52BSSWBU IE-FLD-W53ASSWAS I E-FLD-W53ASSWAU IE-FLD-W53BSSWBS IE-FLD-W53BSSWBU I

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CDF Candidate Description Model Approach (1/yr)

Internal Fire Seismic CC-24R CGS can cross-tie DG-3 to To represent the additional power supply 6.94E-06 1.24E-05 4.86E-06 2.42E-05 either SM-7 or SM-8 by to the HPCS system, the HPCS AC power procedure. Using DG-3 dependency was removed. This removes hardware to cross-tie Division all power dependency (offsite power and 1 and Division 2 is possible onsite power) to HPCS. The PSA model but overload potential of the was modified to accomplish this by adding DG would reduce risk value, a house event gate to remove this This pathway is not of high dependency. Specifically, the power benefit when the DG-3 cross-dependency of SM-4 supply to the HPCS connect is available. Prior system was removed.

NRC approval would be required. Backfeeding the HPCS system with SM-8 would provide a third power source for HPCS. A SAMA candidate to evaluate this is proposed for use in the EOP/SAGs.

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CDF Candidate Description Model Approach (l/yr)

Internal Fire Seismic CC-25R Enhance alternate injection This SAMA candidate examines a PSA 7.55E-06 1.38E-05 4.86E-06 2.62E-05 reliability by including modeling incompleteness. Examine the RHRSW and fire Water cross-risk increase to the PSA for this tie in the maintenance incompleteness, assuming a 10-year program.

mean time between tests for the subject valves. Change the following to failure type 2, with a 10-year mean time between tests:

CONV-MA-1062F2LL now equals 5.7E-04 RHRV-MO-1 15-P3LL now equals 9.9E-02 RHRV-MO-1 16-P3LL now equals 9.9E-02 NOTE: The quantification result becomes the Base Case in the Phase 2 calculations for this candidate. The CDF produced from base case PSA then becomes the benefit case.

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CDF Candidate Description Model Approach (l/yr)

Internal Fire Seismic OT-07R Improve procedures and The model was revised by reducing the 5.61 E-06 1.30E-05 4.86E-06 2.35E-05 operator training to identify top 10 most risk-significant HEPs by a systems and operator actions factor of 10. Based on an importance determined to be important evaluation of the integrated CDF results, from the PSA.

these top ten will represent the potential risk improvement for other important HEPs. Specifically, the following HEP basic events were chosen as representative and were reduced:

ATWH-HPLPRSTH3XX RHRH-ATWSDC-H3XX CIAHUMNX-TIEH3-F CIAHUMNV104BH3-F CIAHUMNV104AH3-F ADSHUMNSTARTH3LT CIAHUMNX-TIEH3XX SLC-XHE-FO-LLVCT ADS-XHE-FO-S2W RHRHUMN-SDC-H3XX FW-05R CGS loss of DC power from The model was revised to remove loss of 7.25E-06 1.28E-05 4.86E-06 2.49E-05 DC Bus E-DP-S1/7 will result E-DP-S1/7 from the RFW initiating event in potential tripping of both equation, and set the unavailability of E-the turbine-driven RFW DP-S1/7 to a very low value (1E-09). This pumps resulting in a low low was accomplished by inserting a house reactor water level which event to remove bus loss from the loss of closes the MSIVs. This RFW initiating event logic and setting the SAMA candidate examines unavailability of E-DP-S1/7 to 1 E-09 the potential for operators to through existing house events XHOSO--

control RFW and avoid a S17--SRVC, XHOS1--S17--SRVC and reactor trip.

EDCDP--S1 7---OOS = 1 E-09.

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CDF Candidate Description Model Approach (1/yr)

Internal Fire Seismic FR-09R Install early fire detection. in The model was revised to simulate the 7.50E-06 1.16E-05 4.86E-06 2.40E-05 the following Reactor Building improvement in detection and mitigation of analysis units: R-1 B, R-1 D, a fire due to early detection in the most R-1J, R-1L, R-1C, R-1K.

important fire areas of the Reactor Building. The ignition frequencies were reduced by factor of 10 to simulate that potential fires would be detected and arrested before becoming a damaging fire.

The following fire area fixed initiating event frequencies were reduced:

FR1 B, NE Reactor bldg 471', RRW = 1.01 FR1 D RB 471, RRW = 1.06 FR1J RB 522', RRW = 1.05 FR1L, RRW = 1.02 FR1C, RRW = 1.03 FR1K, RRW =-1.01

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CDF Candidate Description Model Approach (1/yr)

Internal Fire Seismic FR-08 Protect RHR and SW cables The unavailability for each of two trains of 7.50E-06 6.02E-06 4.86E-06 1.84E-05 from fires.

RHR is set to the value for random unavailability for each train. The FPSA was quantified assuming an unavailability of 2.7E-02 or RHR train A and an unavailability of 2.7E-02 for RHR train B.

The 2.7E-02 unavailability is the square root of the base unavailability for the suppression pool cooling function:

SQRT(7.22E-04)=2.7E-02. Thus, the FPSA is quantified assuming only the random unavailabilities of RHR train A and B (both SPC function and the injection function) apply.

The specific model changes were to quantify the PSA using the following surrogate basic events for the unavailability of RHR A and B:

RHR ---- TRNA-OOS = 2.7E-02 RHR ---- TRN_B-OOS = 2.7E-02 AT-1 5R Modifications to make use of The model was revised to provide added 6.41 E-06 1.37E-05 4.86E-06 2.59E-05 HPCS more likely for ATWS crediting of the manual use of the HPCS (use of auto bypass, installing system by operators during ATWS throttle valve),

conditions. This was accomplished by setting the HPCS control operator action for ATWS to 1 E-3:

Set ATWH-HPLPRSTH3XX to 1 E-03.

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CDF Candidate Description Model Approach (l/yr)

Internal Fire Seismic OT-09R For the non-LOCA initiating Remove the MSIV trip on high steam 7.22E-06 1.26E-05 4.86E-06 2.47E-05 events, credit the Z (PCS tunnel temperature for transient initiators.

recovery) function.

House event xhosO-cs4O was used in the PCS.Igc fault tree to turn off the trip of MSIVs on high steam tunnel temperature.

FR-12R Install early fire detection in The model was revised to simulate the 7.50E-06 1.20E-05 4.86E-06 2.44E-05 the following physical improvement in detection and mitigation of analysis units: T-1A, T-12, T-a fire due to early detection in the most 1C, and T-1 D.

important fire areas of the Turbine Building. The ignition frequencies were reduced by factor of 10 to simulate that potential fires would be detected and arrested before becoming a damaging fire.

The following fire area fixed initiating event frequencies were reduced:

FT12 Turbine Building S Corridors, RRW =

1.01 FT1A Turbine Building W 441', RRW =

1.02 FT1C Turbine Building E 441', RRW =

1.11 FT1 D Turbine building W 471', RRW =

1.01

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 127 of 173 Table B-i: Summary of PSA Cases' Total SAMA Risk Reduction CDF (1/yr)

CDF Candidate Description Model Approach (l/yr)

Internal Fire Seismic FR-11 R Install early fire detection in The model was revised to simulate the 7.50E-06 6.05E-06 4.86E-06 1.84E-05 the following analysis units:

improvement in detection and mitigation of RC-02, RC-03, RC-05, RC-a fire due to early detection in the most 04, RC-07, RC-08, RC-1 1, important fire areas of the Control Building.

RC-14, RC-13, and RC-1A.

The ignition frequencies were reduced by factor of 10 to simulate that potential fires would be detected and arrested before becoming a damaging fire. The following fire area fixed initiating event frequencies were reduced:

FW02-Cable Spreading Room, RRW=1.03 FW03-Cable Chase, RRW=1.07 FW05-Battery room 1, RRW=1.02 FW04-Div 1 Electrical Equipment Room, RRW=1.14 FW07-Div 2 Electrical Equipment Room, RRW=1.14 FW08-Div 2 Switchgear Room, RRW=1.08 FW14-Div 1 Switchgear room, RRW=1.12 FW13,Emergency chiller room, RRW=1.04 FW1A, Radwaste Building 437' RRW=1.03

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 128 of 173 Table B-i: Summary of PSA Cases1 Total SAMA Risk Reduction CDF (1/yr)

CDF Candidate Description Model Approach (1/yr)

Internal Fire Seismic FR-10R Install early fire detection: in The model was revised to simulate the 7.50E-06 1.35E-05 4.86E-06 2.59E-05 the Main Control Room: RC-improvement in detection and mitigation of

10.

a fire due to early detection in the Main Control Room. The ignition frequencies were reduced by factor of 10 to simulate that potential fires would be detected and arrested before becoming a damaging fire.

The Main Control Room fire area fixed initiating event frequency was reduced:

FW10 - Control room, RRW = 1.02 FL-07R Flood protect HPCS, based Set - HPS -----

ISLOCA-R, "HPCS 7.50E-06 1.37E-05 4.86E-06 2.61E-05 on LERF RRW of 1.21, for UNAVAILABLE DUE TO FLOODING HPCS unavailable due to FROM ISLOCA RUPT" to 0.0. This flooding from ISLOCA modeling is such that HPCS is assumed to rupture.

be perfectly protected from flooding due to ISLOCA (i.e., the likelihood is set to zero).

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 129 of 173 Table B-i: Summary of PSA Cases1 Total SAMA Risk Reduction CDF (1/yr)

CDF Candidate Description Model Approach (1/yr)

Internal Fire Seismic AC/DC-30R SAMA candidate AC/DC-1 0 This SAMA candidate adds an additional 7.77E-06 1.09E-05 4.75E-06 2.34E-05 "provide an additional diesel diesel generator that could be aligned to generator" address DG-1 either 4.16 KV bus SM-7 or SM-8. The unavailability. Since DG-2 is diesel generator would differ in design more important to fire risk, an from DG-1 and DG-2 to minimize the additional SAMA candidate to likelihood of diesel generator CCF events.

examine risk improvement for The PSA was modified to make DG-2 DG-2 will be considered.

perfectly reliable to start and run (a different case, AC/DC-10, examined risk benefit from making DG-1 perfectly reliable). To accomplish this, gate G2AC544 was set to a low value.

Additionally, any loss of DG-1 and DG-2 was transferred to the SBO event trees, as this is the definition of SBO at CGS, and produces realistic modeling for this SAMA candidate.

CC-26R Install hard pipe from diesel The existing method of providing the fire 7.48E-06 1.37E-05 4.86E-06 2.60E-05 fire pump to vessel, water injection includes hookup of hoses from the FP system to the condensate system. By eliminating human errors in the model, the hard pipe system effectiveness can be simulated. Set to zero the human failure events for alignment of diesel fire pump to vessel. To accomplish this, set the following HEPs to zero:

FP-HUMN-SBOLH3LL FP-HUMNSYS62H3LL____

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 130 of 173 Table B-i: Summary of PSA Cases1 Total SAMA Risk Reduction CDF (l/yr)

CDF Candidate Description Model Approach (l/yr)

Internal Fire Seismic OT-10R Increase fire pump house For Internal Events, assume a 1.37E-04 7.51 E-06 1.37E-05 4.86E-06 2.61 E-05 building integrity to withstand probability for high wind during a plant higher winds so the fire initiating event (represents a 20 year wind system will be capable of occurring during the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> mission time, withstanding a severe 1/20/365) and a 1.0 probability for high weather event, wind given LOOP (conservative). To the FPW fault tree, add house event XHOS1 -

CS47 to the FPW fault tree to activate these modeling conditions.

FW-04 Add a third RFW pump.

Reduced the RFW unavailability by 1 E-03 4.50E-06 1.03E-05 4.86E-06 1.97E-05 to account for a third train of RFW. No common dependencies are assumed.

Reduce the TF initiating event frequency by at least 3 orders of magnitude. To accomplish this, house event XHOSO-CS48 was used in the RFW.lgc to credit a third RFW train. Event TF and INIT-RY-TF were set to low values.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 131 of 173 Table B-i: Summary of PSA Cases' Total SAMA Risk Reduction CDF (1/yr)

CDF Candidate Description Model Approach (l/yr)

Internal Fire Seismic CB-1 OR Provide additional NDE and The increased testing intervals and 7.34E-06 1.37E-05 4.86E-06 2.59E-05 inspections of MS pipe in locations of critical sections of MS piping turbine building.

outside containment expected to improve detection and timely corrective maintenance. To model this improvement, the MS piping break initiating event was reduced by a factor of two to represent early detection of degrading piping.

Reduce the MS LOCA outside containment initiating event frequencies by a factor of 2:

IE-FLD-TLO--MS-S IE-FLD-TLO--MS-U IE-FLD-TLO--MS-M 1The modeling approach for SAMA candidates that were evaluated in Table E.1 1-1 of the ER was not changed for this sensitivity study.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 132 of 173 Table B-2: Internal Events Benefit Results for Analysis Cases Maximum Case 01 Case 01 Case 01 Case 02 Case 02 Case Benefit (AC/DC-01l)

(AC/DC-02)

(AC/DC-03)

(AC/DC-10)

(AC/DC-15)

Off-site Annual Dose (rem) 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.48E+00 5.48E+00 Off-site Annual Property Loss (S)

$7,079

$7,075

$7,075

$7,075

$7,061

$7,061 Comparison CDF 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 Comparison Dose (rem) 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 Comparison Cost ($)

$7,079

$7,079

$7,079

$7,079

$7,079 Enhanced CDF 7.46E-06 7.46E-06 7.46E-06 7.37E-06 7.37E-06 Reduction in CDF 0.53%

0.53%

0.53%

1.73%

1.73%

Reduction in Off-site Dose 0.00%

0.00%

0.00%

0.18%

0.18%

Immediate Dose Savings (On-site)

$646

$3

$3

$3

$11

$11 Long Term Dose Savings (On-site)

$2,816

$15

$15

$15

$49

$49 Total Accident Related Occupational Exposure (AOE)

$3,462

$18

$18

$18

$60

$60 Cleanup/Decontamination Savings (On-site)

$105,582

- $563

$563

$563

$1,830

$1,830 Replacement Power Savings (On-site)

$155,733

$831

$831

$831

$2,699

$2,699 Averted Costs of On-site Property Damage (AOSC)

$261,315

$1,394

$1,394

$1,394

$4,529

$4,529 Total On-site Benefit

$264,776

$1,412

$1,412

$1,412

$4,589

$4,589 Averted Public Exposure (APE)

$143,289

$0

$0

$0

$261

$261 Averted Off-site Damage Savings (AOC)

$92,381

$52

$52

$52

$235

$235 Total Off-site Benefit

$235,670

$52

$52

$52

$496

$496 Total Benefit (On-site + Off-site)

$500,446

$1,464

$1,464

$1,464

$5,085

$5,085

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 133 of 173 Table B-2: Internal Events Benefit Results for Analysis Cases Case 02 Case 03 Case 04 Case 05 Case 06 Case 07 Case (ACIDC-1 6)

(AC/DC-23)

(AC/DC-27)

(AC/DC-28)

(AC/DC-29)

(AT-05)

Off-site Annual Dose (rem) 5.48E+00 5.16E+00 5.00E+00 5.49E+00 5.48E+00 5.13E+00 Off-site Annual Property Loss ($)

$7,061

$6,659

$6,470

$7,076

$7,073

$6,620 Comparison CDF 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 Comparison Dose (rem) 5.49E+00 5.49E+00 5.49E+00

.5.49E+00 5.49E+00 5.49E+00 Comparison Cost ($)

$7,079

$7,079

$7,079

$7,079

$7,079

$7,079 Enhanced CDF 7.37E-06 7.09E-06 6.73E-06 7.47E-06 7.44E-06 7.36E-06 Reduction in CDF 1.73%

5.47%

10.27%

0.40%

0.80%

1.87%

Reduction in Off-site Dose 0.18%

6.01%

8.93%

0.00%

0.18%

6.56%

Immediate Dose Savings (On-site)

$11

$35

$66

$3

$5

$12 Long Term Dose Savings (On-site)

$49

$154

$289

$11

$23

$53 Total Accident Related Occupational Exposure (AOE)

$60

$189

$355

$14

$28

$65 Cleanup/Decontamination Savings (On-site)

$1,830

$5,772

$10,840

$422

$845

$1,971 Replacement Power Savings (On-site)

$2,699

$8,513

$15,989

$623

$1,246

$2,907 Averted Costs of On-site Property Damage (AOSC)

$4,529

$14,285

$26,828

$1,045

$2,091

$4,878 Total On-site Benefit

$4,589

$14,474

$27,184

$1,059

$2,118

$4,942 Averted Public Exposure (APE)

$261

$8,613

$12,789

$0

$261

$9,396 Averted Off-site Damage Savings (AOC)

$235

$5,481

$7,947

$39

$78

$5,990 Total Off-site Benefit

$496

$14,094

$20,736

$39

$339

$15,386 Total Benefit (On-site + Off-site)

$5,085

$28,568

$47,920

$1,098

$2,458

$20,328

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 134 of 173 Table B-2: Internal Events Benefit Results for Analysis Cases Case 08 Case 09 Case 09 Case 10 Case 11 Case 12 Case (AT-07)

(CB-01)

(CB-03)

(CC-01)

(CC-02)

(CC-03b)

Off-site Annual Dose (rem) 5.49E+00 5.35E+00 5.35E+00 2.40E+00 2.40E+00 5.49E+00 Off-site Annual Property Loss (S)

$7,079

$6,881

$6,881

.$3,267

$3,267

$7,081 Comparison CDF 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 Comparison Dose (rem) 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 Comparison Cost ($)

$7,079

$7,079

$7,079

$7,079

$7,079

$7,079 Enhanced CDF 7.50E-06 7.39E-06 7.39E-06 3.01 E-06 3.01 E-06 7.49E-06 Reduction in CDF 0.00%

1.47%

1.47%

59.87%

59.87%

0.13%

Reduction in Off-site Dose 0.00%

2.55%

2.55%

56.28%

56.28%

0.00%

Immediate Dose Savings (On-site)

$0

$9

$9

$387

$387

$1 Long Term Dose Savings (On-site)

$0

$41

$41

$1,686

$1,686

$4 Total Accident Related Occupational Exposure (AOE)

$0

$51

$51

$2,072

$2,072

$5 Cleanup/Decontamination Savings (On-site)

$0

$1,549

$1,549

$63,209

$63,209

$141 Replacement Power Savings (On-site)

$0

$2,284

$2,284

$93,232

$93,232

$208 Averted Costs of On-site Property Damage (AOSC)

$0

$3,833

$3,833

$156,440

$156,440

$348 Total On-site Benefit

$0

$3,883

$3,883

$158,513

$158,513

$353 Averted Public Exposure (APE)

$0

$3,654

$3,654

$80,649

$80,649

$0 Averted Off-site Damage Savings (AOC)

$0

$2,584

$2,584

$49,747

$49,747

($26)

Total Off-site Benefit

$0

$6,238

$6,238

$130,396

$130,396

($26)

Total Benefit (On-site + Off-site)

$0

$10,121

$10,121

$288,908

$288,908

$327

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 135 of 173 Table B-2: Internal Events Benefit Results for Analysis Cases Case 13 Case 15 Case 18 Case 19 Case 19 Case 20 Case (CC-20)

(CP-01)

(CW-02)

(CW-03)

(CW-04)

(CW-07)

Off-site Annual Dose (rem) 5.45E+00 2.42E+00 4.78E+00 5.45E+00 5.45E+00 4.85E+00 Off-site Annual Property Loss ($)

$7,026

$3,267

$6,211

$7,068

$7,068

$6,317 Comparison CDF 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 Comparison Dose (rem) 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 Comparison Cost ($)

$7,079

$7,079

$7,079

$7,079

$7,079

$7,079 Enhanced CDF 7.45E-06 5.01 E-06 6.74E-06 7.30E-06 7.30E-06 6.70E-06 Reduction in CDF 0.67%

33.20%

10.13%

2.67%

2.67%

10.67%

Reduction in Off-site Dose 0.73%

55.92%

12.93%

0.73%

0.73%

11.66%

Immediate Dose Savings (On-site)

$4

$214

$65

$17

$17

$69 Long Term Dose Savings (On-site)

$19

$935

$285

$75

$75

$300 Total Accident Related Occupational Exposure (AOE)

$23

$1,149

$351

$92

$92

$369 Cleanup/Decontamination Savings (On-site)

$704

$35,053

$10,699

$2,816

$2,816

$11,262 Replacement Power Savings (On-site)

$1,038

$51,703

$15,781

$4,153

$4,153

$16,611 Averted Costs of On-site Property Damage (AOSC)

$1,742

$86,757

$26,480

$6,968

$6,968

$27,874 Total On-site Benefit

$1,765

$87,906

$26,831

$7,061

$7,061

$28,243 Averted Public Exposure (APE)

$1,044

$80,127

$18,531

$1,044

$1,044

$16,704 Averted Off-site Damage Savings (AOC)

$692

$49,747

$11,327

$144

$144

$9,944 Total Off-site Benefit

$1,736

$129,874

$29,858

$1,188

$1,188

$26,648 Total Benefit (On-site + Off-site)

$3,501

$217,779

$56,689

$8,248

$8,248

$54,891

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 136 of 173 Table B-2: Internal Events Benefit Results for Analysis Cases Case 21 Case 22 Case22a Case 23 Case 25 Case 26 Case (FR-03)

(FR-07a)

(FR-07b)

(HV-02)

(SR-03)

(AT-13)

Off-site Annual Dose (rem) 5.49E+00 5.49E+00 5.49E+00 5.48E+00 5.49E+00 5.41 E+00 Off-site Annual Property Loss ($)

$7,079

$7,079

$7,079

$7,069

$7,079

$6,975 Comparison CDF 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 Comparison Dose (rem) 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 Comparison Cost ($)

$7,079

$7,079

$7,079

$7,079

$7,079

$7,079 Enhanced CDF 7.50E-06 7.50E-06 7.50E-06 7.48E-06 7.50E-06 7.46E-06 Reduction in CDF 0.00%

0.00%

0.00%

0.27%

0.00%

0.53%

Reduction in Off-site Dose 0.00%

0.00%,

0.00%

0.18%

0.00%

1.46%

Immediate Dose Savings (On-site)

$0

$0

$0

$2

$0

$3 Long Term Dose Savings (On-site)

$0

$0

$0

$8

$0

$15 Total Accident Related Occupational Exposure (AOE)

$0

$0

$0

$9

$0

$18 Cleanup/Decontamination Savings (On-site)

$0

$0

$0

$282

$0

$563 Replacement Power Savings (On-site)

$0

$0

$0

$415

$0

$831 Averted Costs of On-site Property Damage (AOSC)

$0

$0

$0

$697

$0

$1,394 Total On-site Benefit

$0

$0

$0

$706

$0

$1,412 Averted Public Exposure (APE)

$0

$0

$0

$261

$0

$2,088 Averted Off-site Damage Savings (AOC)

$0

$0

$0

$131

$0

$1,357 Total Off-site Benefit

$0

$0

$0

$391

$0

$3,445 Total Benefit (On-site + Off-site)

$0

$0

$0

$1,098

$0

$4,857

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 137 of 173 Table B-2: Internal Events Benefit Results for Analysis Cases Case 27 Case 28 Case 29 Case 30 Case 31 Case 32 Case (AT-14)

(SR-05R)

(OT-08R)

(FL-05R)

(FL-04R)

(FL-06R)

Off-site Annual Dose (rem) 5.49E+00 5.49E+00 5.47E+00 3.56E+00 3.55E+00 4.51 E+00 Off-site Annual Property Loss ($)

$7,079

$7,079

$7,057

$4,506

$4,490

$5,771 Comparison CDF 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 Comparison Dose (rem) 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 Comparison Cost ($)

$7,079

$7,079

$7,079

$7,079

$7,079

$7,079 Enhanced CDF 7.50E-06 7.50E-06 7.39E-06 6.27E-06 6.26E-06 6.87E-06 Reduction in CDF 0.00%

0.00%

1.47%

16.40%

16.53%

8.40%

Reduction in Off-site Dose 0.00%

0.00%

0.36%

35.15%

35.34%

17.85%

Immediate Dose Savings (On-site)

$0

$0

$9

$106

$107

$54 Long Term Dose Savings (On-site)

$0

$0

$41

$462

$466

$237 Total Accident Related Occupational Exposure (AOE)

$0

$0

$51

$568

$572

$291 Cleanup/Decontamination Savings (On-site)

$0

$0

$1,549

$17,315

$17,456

$8,869 Replacement Power Savings (On-site)

$0

$0

$2,284

$25,540

$25,748

$13,082 Averted Costs of On-site Property Damage (AOSC)

$0.

$0

$3,833

$42,856

$43,204

$21,950 Total On-site Benefit

$0

$0

$3,883

$43,423

$43,776

$22,241 Averted Public Exposure (APE)

$0

$0

$522

$50,373

$50,634

$25,578 Averted Off-site Damage Savings (AOC)

$0

$0

$287

$33,578

$33,786

$17,069 Total Off-site Benefit

$0

$0

$809

$83,951

$84,420

$42,647 Total Benefit (On-site + Off-site)

$0

$0

$4,692

$127,374

$128,197

$64,889

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 138 of 173 Table B-2: Internal Events Benefit Results for Analysis Cases Case 33 Case 34 Case 35 Case 36 Case 37 Case 38 -

Case (CC-24R)

(CC-25R)

(OT-07R)

(FW-05R)

(FR-09R)

(FR-08)

Off-site Annual Dose (rem) 5.1OE+00 5.53E+00 5.05E+00 5.38E+00 5.49E+00 5.49E+00 Off-site Annual Property Loss ($)

$6,588

$7,130

$6,512

$6,951

$7,079

$7,079 Comparison CDF 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 Comparison Dose (rem) 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 Comparison Cost ($)

$7,079

$7,079

$7,079

$7,079

$7,079

$7,079 Enhanced CDF 6.94E-06 7.55E-06 5.61 E-06 7.25E-06 7.50E-06 7.50E-06 Reduction in CDF 7.47%

0.67%

25.20%

3.33%

0.00%

0.00%

Reduction in Off-site Dose 7.10%

0.73%

8.01%

2.00%

0.00%

0.00%

Immediate Dose Savings (On-site)

$48

$4

$163

$22

$0

$0 Long Term Dose Savings (On-site)

$210

$19

$710

$94

$0

$0 Total Accident Related Occupational Exposure (AOE)Y

$258

$23

$872

$115

$0

$0 Cleanup/Decontamination Savings (On-site)

$7,883

$704

$26,607

$3,519

$0

$0 Replacement Power Savings (On-site)

$11,628

$1,038

$39,245

$5,191

$0

$0 Averted Costs of On-site Property Damage (AOSC)

$19,512

$1,742

$65,851

$8,710

$0

$0 Total On-site Benefit

$19,770

$1,765

$66,724

$8,826

$0

$0 Averted Public Exposure (APE)

$10,179

$1,044

$11,484

$2,871

$0

$0 Averted Off-site Damage Savings (AOC)

$6,408

$666

$7,399

$1,670

$0

$0 Total Off-site Benefit

$16,587

$1,710

$18,883

$4,541

$0

$0 Total Benefit (On-site + Off-site)

$36,357

$3,475

$85,607

$13,367

$0

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 139 of 173 Table B-2: Internal Events Benefit Results for Analysis Cases Case 39 Case 40 Case 41 Case 42 Case 43 Case 44 Case (AT-15R)

(OT-09R)

(FR-12R)

(FR-11R)

(FR-10R)

(FL-07R)

Off-site Annual Dose (rem) 5.46E+00 5.22E+00 5.49E+00 5.49E+00 5.49E+00 5.37E+00 Off-site Annual Property Loss ($)

$7,033

$6,731

$7,079

$7,079

$7,079

$6,905 Comparison CDF 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 Comparison Dose (rem) 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 Comparison Cost ($)

$7,079

$7,079

$7,079

$7,079

$7,079

$7,079 Enhanced CDF 6.41 E-06 7.22E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 Reduction in CDF 14.53%

3.73%

0.00%

0.00%

0.00%

0.00%

Reduction in Off-site Dose 0.55%

4.92%

0.00%

0.00%

0.00%

2.19%

Immediate Dose Savings (On-site)

$94

$24

$0

$0

$0

$0 Long Term Dose Savings (On-site)

$409

$105

$0

$0

$0

$0 Total Accident Related Occupational Exposure (AOE)

$503

$129

$0

$0

$0

$0 Cleanup/Decontamination Savings (On-site)

$15,345

$3,942

$0

$0

$0

$0 Replacement Power Savings (On-site)

$22,633

$5,814

,$0

$0

$0

$0

.Averted Costs of On-site Property Damage (AOSC)

$37,978

$9,756

$0

$0

$0

$0 Total On-site Benefit

$38,481

$9,885

$0

$0

$0

$0 Averted Public Exposure (APE)

$783

$7,047

$0

$0

$0

$3,132 Averted Off-site Damage Savings (AOC)

$600

$4,541

$0

$0

$0

$2,271 Total Off-site Benefit

$1,383

$11,588

$0

$0

$0

$5,403 Total Benefit (On-site + Off-site)

$39,864

$21,473

$0

$0

$0

$5,403

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 140 of 173 Table B-2: Internal Events Benefit Results for Analysis Cases Case 45 Case 46 Case 47 Case 48 Case 49 Case 09 Case (AC/DC-30R)

(CC-26R)

(OT-1 OR)

(FW-04)

(CB-1 OR)

(CB-08)

Off-site Annual Dose (rem) 5.54E+00 5.48E+00 5.50E+00 3.20E+00 5.39E+00 5.35E+00 Off-site Annual Property Loss (S)

$7,098

$7,062

$7,087

$4,213

$6,947

$6,881 Comparison CDF 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 7.50E-06 Comparison Dose (rem) 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 5.49E+00 Comparison Cost ($)

$7,079

$7,079

$7,079

$7,079

$7,079

$7,079 Enhanced CDF 7.77E-06 7.48E-06 7.51 E-06 4.50E-06 7.34E-06 7.39E-06 Reduction in CDF

-3.60%

0.27%

0.13%

40.00%

2.13%

1.47%

Reduction in Off-site Dose

-0.91%

0.18%

0.18%

41.71%

1.82%

2.55%

Immediate Dose Savings (On-site)

($23)

$2

$1

$258

$14

$9 Long Term Dose Savings (On-site)

($101)

$8

$4

$1,126

$60

$41 Total Accident Related Occupational Exposure (ACE)

($125)

$9

$5

$1,385

$74

$51 Cleanup/Decontamination Savings (On-site)

($3,801)

$282

$141

$42,233

$2,252

$1,549 Replacement Power Savings (On-site)

($5,606)

$415

$208

$62,293

$3,322

$2,284 Averted Costs of On-site Property Damage (AOSC)

($9,407)

$697

$348

$104,526

$5,575

$3,833 Total On-site Benefit

($9,532)

$706

$353

$105,911

$5,649

$3,883 Averted Public Exposure (APE)

($1,305)

$261

$261

$59,769

$2,610

$3,654 Averted Off-site Damage Savings (AOC)

($248)

$222

$104

$37,401

$1,723

$2,584 Total Off-site Benefit

($1,553)

$483

$365

$97,170

$4,333

$6,238 Total Benefit (On-site + Off-site)

($11,085)

$1,189

$718

$203,081

$9,981

$10,121

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 141 of 173 Table B-2: Internal Events Benefit Results for Analysis Cases Case 09 Case (CB-09)

Off-site Annual Dose (rem) 5.35E+00 Off-site Annual Property Loss ($)

$6,881 Comparison CDF 7.50E-06 Comparison Dose (rem) 5.49E+00 Comparison Cost ($)

$7,079 Enhanced CDF 7.39E-06 Reduction in CDF 1.47%

Reduction in Off-site Dose 2.55%

Immediate Dose Savings (On-site)

$9 Long Term Dose Savings (On-site)

$41 Total Accident Related Occupational Exposure (ACE)

$51 Cleanup/Decontamination Savings (On-site)

$1,549 Replacement Power Savings (On-site)

$2,284 Averted Costs of On-site Property Damage (AOSC)

$3,833 Total On-site Benefit

$3,883 Averted Public Exposure (APE)

$3,654 Averted Off-site Damage Savings (AOC)

$2,584 Total Off-site Benefit

$6,238 Total Benefit (On-site + Off-site)

$10,121

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 142 of 173 Table B-3: Fire Benefit Results for Analysis Cases Maximum Case 01 Case 01 Case 01 Case 02 Case 02 Case Benefit (AC/DC-01)

(AC/DC-02)

(AC/DC-03)

(AC/DC-10)

(AC/DC-15)

Off-site Annual Dose (rem) 8.96E+-00 8.96E+00 8.96E+00 8.96E+00 8.32E+00 8.32E+00 Off-site Annual Property Loss ($)

$11,168

$11,168

$11,168

$11,168

$10,370

$10,370 Comparison CDF 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 Comparison Dose (rem) 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 Comparison Cost ($)

$11,168

$11,168

$11,168

$11,168

$11,168.

Enhanced CDF 1.37E-05 1.37E-05 1.37E-05 1.24E-05 1.24E-05 Reduction in CDF 0.00%

0.00%

0.00%

9.49%

9.49%

Reduction in Off-site Dose 0.00%

0.00%

0.00%

7.14%

7.14%

Immediate Dose Savings (On-site)

$1,180

$0

$0

$0

$112

$112 Long Term Dose Savings (On-site)

$5,143

$0

$0

$0

$488

$488 Total Accident Related Occupational Exposure (AOE)

$6,323

$0

$0

$0

$600

$600 Cleanup/Decontamination Savings (On-site)

$192,864

$0

$0

$0

$18,301

$18,301 Replacement Power Savings (On-site)

$284,471

$0

$0

$0

$26,994

$26,994 Averted Costs of On-site Property Damage (AOSC)

$477,335

$0

$0

$0

$45,295

$45,295 Total On-site Benefit

$483,658

$0

$0

$0

$45,895

$45,895 Averted Public Exposure (APE)

$233,856

$0

$0

$0

$16,704

$16,704 Averted Off-site Damage Savings (AOC)

$145,742

$0

$0

$0

$10,414

$10,414 Total Off-site Benefit

$379,598

$0

$0

$0

$27,118

$27,118 Total Benefit (On-site + Off-site)

$863,256

$0

$0

$0

$73,012

$73,012

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 143 of 173 Table B-3: Fire Benefit Results for Analysis Cases Case 02 Case 03 Case 04 Case 05 Case 06 Case 07 Case (AC/DC-16)

(AC/DC-23)

(AC/DC-27)

(AC/DC-28)

(AC/DC-29)

(AT-05)

Off-site Annual Dose (rem) 8.32E+00 8.80E+00 5.69E+00 8.94E+00 8.91 E+00 8.96E+00 Off-site Annual Property Loss ($)

$10,370

$10,967

$7,123

$11,149

$11,107

$11,168 Comparison CDF 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 Comparison Dose (rem) 8.96E+00 8.96E+00 8.96E+00

.8.96E+00 8.96E+00 8.96E+00 Comparison Cost ($)

$11,168

$11,168

$11,168

$11,168

$11,168

$11,168 Enhanced CDF 1.24E-05 1.35E-05 8.50E-06 1.36E-05 1.34E-05 1.37E-05 Reduction in CDF 9.49%

1.46%

37.96%

0.73%

2.19%

0.00%

Reduction in Off-site Dose 7.14%

1.79%

36.50%

0.22%

0.56%

0.00%

Immediate Dose Savings (On-site)

$112

$17

$448

$9

$26

$0 Long Term Dose Savings (On-site)

$488

$75

$1,952

$38

$113

$0 Total Accident Related Occupational Exposure (AOE)

$600

$92

$2,400

$46

$138

$0 Cleanup/Decontamination Savings (On-site)

$18,301

$2,816

$73,204

$1,408

$4,223

$0 Replacement Power Savings (On-site)

$26,994

$4,153

$107,975

$2,076

$6,229

$0 Averted Costs of On-site Property Damage (AOSC)

$45,295

$6,968

$181,178

$3,484

$10,453

$0 Total On-site Benefit

$45,895

$7,061

$183,578

$3,530

$10,591

$0 Averted Public Exposure (APE)

$16,704

$4,176

$85,347

$522

$1,305

$0 Averted Off-site Damage Savings (AOC)

$10,414

$2,623

$52,787

$248

$796

$0 Total Off-site Benefit

$27,118

$6,799

$138,134

$770

$2,101

$0 Total Benefit (On-site + Off-site)

$73,012

$13,860

$321,712

$4,300

$12,692

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 144 of 173 Table B-3: Fire Benefit Results ior Analysis Cases Case 08 Case 09 Case 09 Case 10 Case 11 Case 12 Case

_(AT-07)

(CB-01)

(CB-03)

(CC-01)

(CC-02)

(CC-03b)

Off-site Annual Dose (rem) 8.96E+00 8.96E+00 8.96E+00 3.08E+00 3.08E+00 8.96E+00 Off-site Annual Property Loss ($)

$11,168

$11,168

$11,168

$3,869

$3,869

$11,174 Comparison CDF 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 Comparison Dose (rem) 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 Comparison Cost ($)

$11,168

$11,168

$11,168

$11,168

$11,168

$11,168 Enhanced CDF 1.37E-05 1.37E-05 1.37E-05 3.55E-06 3.55E-06 1.37E-05 Reduction in CDF 0.00%

0.00%

0.00%

74.09%

74.09%

0.00%

Reduction in Off-site Dose 0.00%

0.00%

0.00%

65.63%

65.63%

0.00%

Immediate Dose Savings (On-site)

$0

$0

$0

$874

$874

$0 Long Term Dose Savings (On-site)

$0

$0

$0

$3,810

$3,810

$0 Total Accident Related Occupational Exposure (AOE)

$0

$0

$0

$4,685

$4,685

$0 Cleanup/Decontamination Savings (On-site)

$0

$0

$0

$142,888

$142,888

$0 Replacement Power Savings (On-site)

$0

$0

$0

$210,758

$210,758

$0 Averted Costs of On-site Property Damage (AOSC)

$0

$0

$0

$353,646

$353,646

$0 Total On-site Benefit

$0

$0

$0

$358,331

$358,331

$0 Averted Public Exposure (APE)

$0

$0

$0

$153,468

$153,468

$0 Averted Off-site Damage Savings (AOC)

$0

$0

$0

$95,252

$95,252

($78)

Total Off-site Benefit

$0

$0

$0

$248,720

$248,720

($78)

Total Benefit (On-site + Off-site)

$0

$0

$0

$607,051

$607,051

($78)

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 145 of 173 Table B-3: Fire Benefit Results for Analysis Cases Case 13 Case 15 Case I8 Case 19 Case 19 Case 20 Case (CC-20)

(CP-01)

(CW-02)

(CW-03)

(CW-04)

(CW-07)

Off-site Annual Dose (rem) 8.95E+00 1.52E+00 9.81 E+00 9.79E+00 9.79E+00 8.44E+00 Off-site Annual Property Loss ($)

$11,159

$1,743

$12,301

$12,298

$12,298

$10,602 Comparison CDF 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 Comparison Dose (rem) 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 Comparison Cost ($)

$11,168

$11,168

$11,168

$11,168

$11,168

$11,168 Enhanced CDF 1.37E-05 6.36E-06 1.30E-05 1.33E-05 1.33E-05 1.20E-05 Reduction in CDF 0.00%

53.58%

5.11%

2.92%

2.92%

12.41%

Reduction in Off-site Dose 0.11%

83.04%

-9.49%

-9.26%

-9.26%

5.80%

Immediate Dose Savings (On-site)

$0

$632

$60

$34

$34

$146 Long Term Dose Savings (On-site)

$0

$2,755

$263

$150

$150

$638 Total Accident Related Occupational Exposure (AOE)

$0

$3,388

$323

$185

$185

$785 Cleanup/Decontamination Savings (On-site)

$0

$103,330

$9,854

$5,631

$5,631

$23,932 Replacement Power Savings (On-site)

$0

$152,410

$14,535

$8,306

$8,306

$35,299 Averted Costs of On-site Property Damage (AOSC)

$0

$255,740

$24,389

$13,937

$13,937

$59,231 Total On-site Benefit

$0

$259,128

$24,712

$14,121

$14,121

$60,016 Averted Public Exposure (APE)

$261

$194,184

($22,185)

($21,663)

($21,663)

$13,572 Averted Off-site Damage Savings (AOC)

$117

$122,996

($14,786)

($14,747)

($14,747)

$7,386 Total Off-site Benefit

$378

$317,180

($36,971)

($36,410)

($36,410)

$20,958 Total Benefit (On-site + Off-site)

$378

$576,308

($12,258)

($22,288)

($22,288)

$80,974

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 146 of 173 Table B-3: Fire Benefit Results for Analysis Cases Case 21 Case 22 Case22a Case 23 Case 25 Case 26 Case (FR-03)

(FR-07a)

(FR-07b)

(HV-02)

(SR-03)

(AT-13)

Off-site Annual Dose (rem) 8.78E+00 4.79E+00 8.56E+00 8.96E+00 8.96E+00 8.96E+00 Off-site Annual Property Loss ($)

$10,955

$5,872

$10,665

$11,166

$11,168

$11,168 Comparison CDF 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 Comparison Dose (rem) 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 Comparison Cost ($)

$11,168

$11,168

$11,168

$11,168

$11,168

$11,168 Enhanced CDF 1.29E-05 9.60E-06 1.33E-05 1.37E-05 1.37E-05 1.37E-05 Reduction in CDF 5.84%

29.93%

2.92%

0.00%

0.00%

0.00%

Reduction in Off-site Dose 2.01%

46.54%

4.46%

0.00%

0.00%

0.00%

Immediate Dose Savings (On-site)

$69

$353

$34

$0

$0

$0 Long Term Dose Savings (On-site)

$300

$1,539

$150

$0

$0

$0 Total Accident Related Occupational Exposure (AOE)

$369

$1,892

$185

$0

$0

$0 Cleanup/Decontamination Savings (On-site)

$11,262

$57,718

$5,631

$0

$0

$0 Replacement Power Savings (On-site)

-$16,611

$85,134

$8,306

$0

$0

$0 Averted Costs of On-site Property Damage (AOSC)

$27,874

$142,852

$13,937

$0

$0

$0 Total On-site Benefit

$28,243

$144,744

$14,121

$0

$0

$0 Averted Public Exposure (APE)

$4,698

$108,837

$10,440

$0

$0

$0 Averted Off-site Damage Savings (AOC)

$2,780

$69,113

$6,564

$26

$0

$0 Total Off-site Benefit

$7,478

$177,950

$17,004

$26

$0

$0 Total Benefit (On-site + Off-site)

$35,720

$322,694

$31,126

$26

$0

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 147 of 173 Table B-3: Fire Benefit Results for Analysis Cases Case 27 Case 28 Case 29 Case 30 Case 31 Case 32 Case (AT-14)

(SR-05R)

(OT-08R)

(FL-05R)

(FL-04R)

(FL-06R)

Off-site Annual Dose (rem) 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 Off-site Annual Property Loss($)

$11,168

$11,168

$11,168

$11,168

$11,168

$11,168 Comparison CDF 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 Comparison Dose (rem) 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 Comparison Cost ($)

$11,168

$11,168

$11,168

$11,168

$11,168

$11,168 Enhanced CDF 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 Reduction in CDF 0.00%

0.00%

0.00%

0.00%

0.00%

0.00%

Reduction in Off-site Dose 0.00%

0.00%

0.00%

0.00%

0.00%

0.00%

Immediate Dose Savings (On-site)

$0

$0

$0

$0

$0

$0 Long Term Dose Savings (On-site)

$0

$0

$0

$0

$0

$0 Total Accident Related Occupational Exposure (AOE)

$0

$0

$0

$0

$0

$0 Cleanup/Decontamination Savings (On-site)

$0

$0

$0

$0

$0

$0 Replacement Power Savings (On-site)

$0

$0

$0

$0

$0

$0 Averted Costs of On-site Property Damage (AOSC)

$0

$0

$0

$0

$0

$0 Total On-site Benefit

$0

$0

$0

$0

$0

$0 Averted Public Exposure (APE)

$0

$0

$0

$0

$0

$0 Averted Off-site Damage Savings (AOC)

$0

$0

$0

$0

$0

$0 Total Off-site Benefit

$0

$0

$0

$0

$0

$0 Total Benefit (On-site + Off-site)

$0

$0

$0

$0

$0

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 148 of 173 Table B-3: Fire Benefit Results for Analysis Cases Case 33 Case 34 Case 35 Case 36 Case 37 Case 38 Case (CC-24R)

(CC-25R)

(OT-07R)

(FW-05R)

(FR-09R)

(FR-08)

Off-site Annual Dose (rem) 7.80E+00 8.93E+00 8.92E+00 8.64E+00 8.31 E+00 3.25E+00 Off-site Annual Property Loss ($)

$9,711

$11,174

$11,120

$10,788

$10,387

$4,056 Comparison CDF 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 Comparison Dose (rem) 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E00.

Comparison Cost ($)

$11,168

$11,168

$11,168

$11,168

$11,168

$11,168 Enhanced CDF 1.24E-05 1.38E-05 1.30E-05 1.28E-05 1.16E-05 6.02E-06 Reduction in CDF 9.49%

0.73%

5.11%

6.57%

15.33%

56.06%

Reduction in Off-site Dose 12.95%

0.33%

0.45%

3.57%

7.25%

63.73%

Immediate Dose Savings (On-site)

$112

$9

$60

$78

$181

$661 Long Term Dose Savings (On-site)

$488

$38

$263

$338

$788

$2,883 Total Accident Related Occupational Exposure (AOE)

$600

$46

$323

$415

$969

$3,545 Cleanup/Decontamination Savings (On-site)

$18,301

$1,408

$9,854

$12,670

$29,563

$108,116 Replacement Power Savings (On-site)

$26,994

$2,076

$14,535

$18,688

$43,605

$159,470 Averted Costs of On-site Property Damage (AOSC)

$45,295

$3,484

$24,389

$31,358

$73,168

$267,586 Total On-site Benefit

$45,895

$3,530

$24,712

$31,773

$74,137

$271,131 Averted Public Exposure (APE)

$30,276

$783

$1,044

$8,352

$16,965

$149,031 Averted Off-site Damage Savings (AOC)

$19,014

$78

$626

$4,959

$10,192

$92,812 Total Off-site Benefit

$49,290

$861

$1,670

$13,311

$27,157

$241,843 Total Benefit (On-site + Off-site)

$95,184

$4,392

$26,383

$45,084

$101,294

$512,974

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 149 of 173 Table B-3: Fire Benefit Results for Analysis Cases Case 39 Case 40 Case 41 Case 42 Case 43 Case 44 Case (AT-15R)

(OT-09R))

(FR-12R)

(FR-11RR)

(FR-10R)

(FL-07R)

Off-site Annual Dose (rem) 8.96E+00 7.81 E+00 7.90E+00 3.33E+00 8.80E+00 8.96E+00 Off-site Annual Property Loss ($)

$11,168

$9,716

$9,831

$4,140

$10,976

$11,168 Comparison CDF 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 Comparison Dose (rem) 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 Comparison Cost ($)

$11,168

$11,168

$11,168

$11,168

$11,168

$11,168 Enhanced CDF 1.37E-05 1.26E-05 1.20E-05 6.05E-06 1.35E-05 1.37E-05 Reduction in CDF 0.00%

8.03%

12.41%

55.84%

1.46%

0.00%

Reduction in Off-site Dose 0.00%

12.83%

11.83%

62.83%

1.79%

0.00%

Immediate Dose Savings (On-site)

$0

$95

$146

$659

$17

$0 Long Term Dose Savings (On-site)

$0

$413

$638

$2,872

$75

$0 Total Accident Related Occupational Exposure (AOE)

$0

$508

$785

$3,531

$92

$0 Cleanup/Decontamination Savings (On-site)

$0

$15,485

$23,932

$107,694

$2,816

$0 Replacement Power Savings (On-site)

$0

$22,841

$35,299

$158,847

$4,153

$0 Averted Costs of On-site Property Damage (AOSC)

$0

$38,326

$59,231

$266,541

$6,968

$0 Total On-site Benefit

$0

$38,834

$60,016

$270,072

$7,061

$0 Averted Public Exposure (APE)

$0

$30,015

$27,666

$146,943

$4,176

$0 Averted Off-site Damage Savings (AOC)

$0

$18,949

$17,448

$91,715

$2,506

$0 Total Off-site Benefit

$0

$48,964

$45,114

$238,658

$6,682

$0 Total Benefit (On-site + Off-site)

$0

$87,797

$105,130

$508,730

$13,742

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 150 of 173 Table B-3: Fire BenefitResults for Analysis Cases Case 45 Case 46 Case 47 Case 48 Case 49 Case 09 Case (AC/DC-30R)

(CC-26R)

(OT-1OR)

(FW-04)

(CB-10R)

(CB-08)

Off-site Annual Dose (rem) 7.32E+00 8.88E+00 8.96E+00 6.64E+00 8.96E+00 8.96E+00 Off-site Annual Property Loss ($)

$9,156

$11,070

$11,170

$8,262

$11,168

$11,168 Comparison CDF 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 1.37E-05 Comparison Dose (rem) 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 8.96E+00 Comparison Cost ($)

$11,168

$11,168

$11,168

$11,168

$11,168

$11,168 Enhanced CDF 1.09E-05 1.37E-05 1.37E-05 1.03E-05 1.37E-05 1.37E-05 Reduction iniCDF 20.44%

0.00%

0.00%

24.82%

0.00%

0.00%

Reduction in Off-site Dose 18.30%

0.89%

0.00%

25.89%

0.00%

0.00%

Immediate Dose Savings (On-site)

$241

$0

$0

$293

$0

$0 Long Term Dose Savings (On-site)

$1,051

$0

$0

$1,276

$0

$0 Total Accident Related Occupational Exposure (AOE)

$1,292

$0

$0

$1,569

$0

$0 Cleanup/Decontamination Savings (On-site)

$39,417

$0

$0

$47,864

$0

$0 Replacement Power Savings (On-site)

$58,140

$0

$0

$70,599

$0

$0 Averted Costs of On-site Property Damage (AOSC)

$97,558

$0

$0

$118,463

$0

$0 Total On-site Benefit

$98,850

$0

$0

$120,032

$0

$0 Averted Public Exposure (APE)

$42,804

$2,088

$0

$60,552

$0

$0 Averted Off-site Damage Savings (AOC)

$26,257

$1,279

$26

$37,923

$0

$0 Total Off-site Benefit

$69,061

$3,367

$26

$98,475

$0

$0 Total Benefit (On-site + Off-site)

$167,910

$3,367

$26

$218,507

$0

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 151 of 173 Table B-3: Fire Benefit Results for Analysis Cases Case 09 Case (CB-09)

Off-site Annual Dose (rem) 8.96E+00 Off-site Annual Property Loss ($)

$11,168 Comparison CDF 1.37E-05 Comparison Dose (rem) 8.96E+00 Comparison Cost ($)

$11,168 Enhanced CDF 1.37E-05 Reduction in CDF 0.00%

Reduction in Off-site Dose 0.00%

Immediate Dose Savings (On-site)

$0 Long Term Dose Savings (On-site)

$0 Total Accident Related Occupational Exposure (AOE)

$0 Cleanup/Decontamination Savings (On-site)

$0 Replacement Power Savings (On-site)

$0 Averted Costs of On-site Property Damage (AOSC)

$0 Total On-site Benefit

$0 Averted Public Exposure (APE)

$0 Averted Off-site Damage Savings (AOC)

$0 Total Off-site Benefit

$0 Total Benefit (On-site + Off-site)

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 152 of 173 Table B-4: Seismic Benefit Results for Analysis Cases Maximum Case 01 Case 01 Case 01 Case 02 Case 02 Case Benefit (AC/DC-01)

(AC/DC-02)

(AC/DC-03)

(AC/DC-10)

(AC/DC-15)

Off-site Annual Dose (rem) 5.91-E+00 5.90E+00 5.90E+00 5.90E+00 5.82E+00 5.82E+00 Off-site Annual Property Loss ($)

$8,444

$8,436

$8,436

$8,436

$8,311

$8,311 Comparison CDF 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Comparison Dose (rem) 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Comparison Cost ($)

$8,444

$8,444

$8,444

$8,444

$8,444 Enhanced CDF 4.86E-06 4.86E-06 4.86E-06 4.83E-06 4.83E-06 Reduction in CDF 0.00%

0.00%

0.00%

0.62%

0.62%

Reduction in Off-site Dose 0.17%

0.17%

0.17%

1.52%

1.52%

Immediate Dose Savings (On-site)

$419

$0

$0

$0

$3

$3 Long Term Dose Savings (On-site)

$1,824

$0

$0

$0

$11

$11 Total Accident Related Occupational Exposure (AOE)

$2,243

$0

$0

$0

$14

$14 Cleanup/Decontamination Savings (On-site)

$68,417

$0

$0

$0

$422

$422 Replacement Power Savings (On-site)

$100,915

$0

$0

$0

$623

$623 Averted Costs of On-site Property Damage (AOSC)

$169,332

$0

$0

$0

$1,045

$1,045 Total On-site Benefit

$171,575

$0

$0

$0

$1,059

$1,059 Averted Public Exposure (APE)

$154,251

$261

$261

$261

$2,349

$2,349 Averted Off-site Damage Savings (AOC)

$110,194

$104

$104

$104

$1,736

$1,736 Total Off-site Benefit

$264,445

$365

$365

$365

$4,085

$4,085 Total Benefit (On-site + Off-site)

$436,020

$365

$365

$365

$5,144

$5,144

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 153 of 173 Table B-4: Seismic Benefit Results for Analysis Cases Case 02 Case 03 Case 04 Case 05 Case 06 Case 07 Case (AC/DC-16)

(AC/DC-23)

(AC/DC-27)

(AC/DC-28)

(AC/DC-29)

(AT-05)

Off-site Annual Dose (rem) 5.82E+00 5.91 E+00 5.91 E+00 5.90E+00 5.90E+00 5.89E+00 Off-site Annual Property Loss (S)

$8,311

$8,444

$8,444

$8,441

$8,437

$8,429 Comparison CDF 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Comparison Dose (rem) 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Comparison Cost ($)

$8,444

$8,444

$8,444

$8,444

$8,444

$8,444 Enhanced CDF 4.83E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Reduction in CDF 0.62%

0.00%

0.00%

0.00%

0.00%

0.00%

Reduction in Off-site Dose 1.52%

0.00%

0.00%

0.17%

0.17%

0.34%

Immediate Dose Savings (On-site)

$3

$0

$0

$0

$0

$0 Long Term Dose Savings (On-site)

$11

$0

$0

$0

$0

$0 Total Accident Related Occupational Exposure iAOE)

$14

$0

$0

$0

$0

$0 Clean up/Decontam ination Savings (On-site)

$422

$0

$0

$0

$0

$0 Replacement Power Savings (On-site)

$623

$0

$0

$0

$0

$0 Averted Costs of On-site Property Damage (AOSC)

$1,045

$0

$0

$0

$0

$0 Total On-site Benefit

$1,059

$0

$0

$0

$0

$0 Averted Public Exposure (APE)

$2,349

$0

$0

$261

$261

$522 Averted Off-site Damage Savings (AOC)

$1,736

$0

$0

$39

$91

$196 Total Off-site Benefit

$4,085

$0

$0

$300

$352

$718 Total Benefit (On-site + Off-site)

$5,144

$0

$0

$300

$352

$718

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 154 of 173 Table B-4: Seismic Benefit Results for Analysis Cases Case 08 Case 09 Case 09 Case 10 Case 11 Case 12 Case (AT-07)

(CB-01)

(CB-03)

(CC-01)

(CC-02)

(CC-03b)

Off-site Annual Dose (rem) 5.91 E+00 5.91 E+00 5.91 E+00 5.80E+00 5.80E+00 5.91 E+00 Off-site Annual Property Loss ($)

$8,444

$8,444

$8,444

$8,309

$8,309

$8,444 Comparison CDF 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Comparison Dose (rem) 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Comparison Cost ($)

$8,444

$8,444

$8,444

$8,444

$8,444

$8,444 Enhanced CDF 4.86E-06 4.86E-06 4.86E-06 4.74E-06 4.74E-06 4.86E-06 Reduction in CDF 0.00%

0.00%

0.00%

2.47%

2.47%

0.00%

Reduction in Off-site Dose 0.00%

0.00%

0.00%

1.86%

1.86%

0.00%

Immediate Dose Savings (On-site)

$0

$0

$0

$10

$10

$0 Long Term Dose Savings (On-site)

$0

$0

$0

$45

$45

$0 Total Accident Related Occupational Exposure (AOE) -

$0

$0

$0

$55

$55

$0 Cleanup/Decontamination Savings (On-site)

$0

$0

$0

$1,689

$1,689

$0 Replacement Power Savings (On-site)

$0

$0

$0

$2,492

$2,492

$0 Averted Costs of On-site Property Damage (AOSC)

$0

$0

$0

$4,181

$4,181

$0 Total On-site Benefit

$0

$0

$0

$4,236

$4,236

$0 Averted Public Exposure (APE)

$0

$0

$0

$2,871

$2,871

$0 Averted Off-site Damage Savings (AOC)

$0

$0

$0

$1,762

$1,762

$0 Total Off-site Benefit

$0

$0

$0

$4,633

$4,633

$0 Total Benefit (On-site + Off-site)

$0

$0

$0

$8,869

$8,869

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 155 of 173 Table B-4: Seismic Benefit Results for Analysis Cases Case 13 Case 15 Case 18 Case 19 Case 19 Case 20 Case (CC-20)

(CP-01)

(CW-02)

(CW-03)

(CW-04)

(CW-07)

Off-site Annual Dose (rem) 5.91 E+00 5.85E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.90E+00 Off-site Annual Property Loss ($)

$8,444

$8,370

$8,444

$8,444

$8,444

$8,434 Comparison CDF 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Comparison Dose (rem) 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Comparison Cost ($)

$8,444

$8,444

$8,444

$8,444

$8,444

$8,444 Enhanced CDF 4.86E-06 4.82E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Reduction in CDF 0.00%

0.82%

0.00%

0.00%

0.00%

0.00%

Reduction in Off-site Dose 0.00%

1.02%

0.00%

0.00%

0.00%

0.17%

Immediate Dose Savings (On-site)

$0

$3

$0

$0

$0

$0 Long Term Dose Savings (On-site)

$0

$15

$0

$0

$0

- $0 Total Accident Related Occupational Exposure (AOE)

$0

$18

$0

$0

$0

$0 Cleanup/Decontamination Savings (On-site)

$0

$563

$0

$0

$0

$0 Replacement Power Savings (On-site)

$0

$831

$0

$0

$0

$0 Averted Costs of On-site Property Damage (AOSC)

$0

$1,394

$0

$0

$0

$0 Total On-site Benefit

$0

$1,412

$0

$0

$0

$0 Averted Public Exposure (APE)

$0

$1,566

$0

$0

$0

$261 Averted Off-site Damage Savings (AOC)

$0

$966

$0

$0

$0

$131 Total Off-site Benefit

$0

$2,532

$0

$0

$0

$391 Total Benefit (On-site + Off-site)

$0

$3,944

$0

$0

$0

$391

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 156 of 173 Table B-4: Seismic Benefit Results for Analysis Cases Case 21 Case 22 Case22a Case 23 Case 25 Case 26 Case (FR-03)

(FR-07a)

(FR-07b)

(HV-02)

(SR-03)

(AT-13)

Off-site Annual Dose (rem) 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.87E+00 5.91 E+00 Off-site Annual Property Loss ($)

$8,444

$8,444

$8,444

$8,444

$8,395

$8,444 Comparison CDF.

4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Comparison Dose (rem) 5.91E+00 5.91E+00 5.91 E+00 5.91E+00 5.91 E+00 5.91E+00 Comparison Cost ($)

$8,444

$8,444

$8,444

$8,444

$8,444

$8,444 Enhanced CDF 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.82E-06 4.86E-06 Reduction in CDF 0.00%

0.00%

0.00%

0.00%

0.82%

0.00%

Reduction in Off-site Dose 0.00%

0.00%

0.00%

0.00%

0.68%

0.00%

Immediate Dose Savings (On-site)

$0

$0

$0

$0

$3

$0 Long Term Dose Savings (On-site)

$0

$0

$0

$0

$15

$0 Total Accident Related Occupational Exposure (AOE)

$0

$0

$0

$0

$18

$0 Cleanup/Decontamination Savings (On-site)

$0

$0

$0

$0

$563

$0 Replacement Power Savings (On-site)

$0

$0

$0

$0

$831

$0 Averted Costs of On-site Property Damage (AOSC)

$0

$0

$0

$0

$1,394

$0 Total On-site Benefit

$0

$0

$0

$0

$1,412

$0 Averted Public Exposure (APE)

$0

$0

$0

$0

$1,044

$0 Averted Off-site Damage Savings (AOC)

$0

$0

$0

$0

$639

$0 Total Off-site Benefit

$0

$0

$0

$0

$1,683

$0 Total Benefit (On-site + Off-site)

$0

$0

$0

$0

$3,096

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 157 of 173 Table B-4: Seismic Benefit Results for Analysis Cases Case 27 Case 28 Case 29 Case 30 Case 31 Case 32 Case (AT-14)

(SR-05R)

(OT-08R)

(FL-05R)

(FL-04R)

(FL-06R)

Off -site Annual Dose (rem) 5.91 E+00 6.52E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Off-site Annual Property Loss ($)

$8,444

$9,165

$8,444

$8,444

$8,444

$8,444 Comparison CDF 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Comparison Dose (rem) 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Comparison Cost ($)

$8,444

$8,444

$8,444

$8,444

$8,444

$8,444 Enhanced CDF 4.86E-06 5.76E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Reduction in CDF 0.00%

18.52%

0.00%

0.00%

0.00%

0.00%

Reduction in Off-site Dose 0.00%

10.32%

0.00%

0.00%

0.00%

0.00%

Immediate Dose Savings (On-site)

$0

$78

$0

$0

$0

$0 Long Term Dose Savings (On-site)

$0

$338

$o

$0

$0

$0 Total Accident Related Occupational Exposure (AOE)

$0

$415

$0

$0

$0

$0 Cleanup/Decontamination Savings (On-site)

$0

$12,670

$0

$0

$0

$0 Replacement Power Savings (On-site)

$0

$18,688

$0

$0

$0

$0 Averted Costs of On-site Property Damage (AOSC)

$0

$31,358

$0

$0

$0

$0 Total On-site Benefit

$0

$31,773

$0

$0

$0

$0 Averted Public Exposure (APE)

$0

$15,921

$0

$0

$0

$0 Averted Off-site Damage Savings (AOC)

$0

$9,409

$0

$0

$0

$0 Total Off-site Benefit

$0

$25,330

$0

$0

$0

$0 Total Benefit (On-site + Off-site)

$0

$57,103

$0

$0

$0

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 158 of 173 Table B-4: Seismic Benefit Results for Analysis Cases Case 33 Case 34 Case 35 Case 36 Case 37 Case 38 Case (CC-24R)

(CC-25R)

(OT-07R)

(FW-05R)

(FR-09R)

(FR-08)

Off-site Annual Dose (rem) 5.91 E+00 5.90E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Off-site Annual Property Loss ($)

$8,444

$8,445

$8,444

$8,444

$8,444

$8,444 Comparison CDF 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Comparison Dose (rem) 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Comparison Cost ($)

$8,444

$8,444

$8,444

$8,444

$8,444

$8,444 Enhanced CDF 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Reduction in CDF 0.00%

0.00%

0.00%

0.00%

0.00%

0.00%

Reduction in Off-site Dose 0.00%

0.17%

0.00%

0.00%

0.00%

0.00%

Immediate Dose Savings (On-site)

$0

$0

$0

$0

$0

$0 Long Term Dose Savings (On-site)

$0

$0

$0

$0

$0

$0 Total Accident Related Occupational Exposure (AOE)

$0

$0

$0

$0

$0

$0 Cleanup/Decontamination Savings (On-site)

$0

$0

$0

$0

$0

$0 Replacement Power Savings (On-site)

$0

$0

$0

$0

$0

$0 Averted Costs of On-site Property Damage (AOSC)

$0

$0

$0

$0

$0

$0 Total On-site Benefit

$0

$0

$0

$0

$0

$0 Averted Public Exposure (APE)

$0

$261

$0

$0

$0

$0 Averted Off-site Damage Savings (AOC)

$0

$13

$0

$0

$0

$0 Total Off-site Benefit

$0

$274

$0

$0

$0

$0 Total Benefit (On-site + Off-site)

$0

$274

$0

$0

$0

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 159 of 173 Table B-4: Seismic Benefit Results for Analysis Cases Case 39 Case 40 Case 41 Case 42 Case 43 Case 44 Case (AT-15R)

(OT-09R)

(FR-12R)

(FR-11R)

(FR-10Ri)

(FL-07R)

Off-site Annual Dose (rem) 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Off-site Annual Property Loss (S)

$8,444

$8,444

$8,444

$8,444

$8,444

$8,444 Comparison CDF 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Comparison Dose (rem) 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Comparison Cost ($)

$8,444

$8,444

$8,444

$8,444

$8,444

$8,444 Enhanced CDF 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Reduction in CDF 0.00%

0.00%

0.00%

0.00%

0.00%

0.00%

Reduction in Off-site Dose 0.00%

0.00%

0.00%

0.00%

0.00%

0.00%

Immediate Dose Savings (On-site)

$0

$0

$0

$0

$0

$0 Long Term Dose Savings (On-site)

$0

$0

$0

$0

$0

$0 Total Accident Related Occupational Exposure (AOE)

$0

$0

$0

$0

$0

$0 Cleanup/Decontamination Savings (On-site)

$0

$0

$0

$0

$0

$0 Replacement Power Savings (On-site)

$0

$0

$0

$0

$0

$0 Averted Costs of On-site Property Damage (AOSC)

$0

$0

$0

$0

$0

$0 Total On-site Benefit

$0

$0

$0

$0

$0

$0 Averted Public Exposure (APE)

$0

$0

$0

$0

$0

$0 Averted Off-site Damage Savings (AOC)

$0

$0

$0

$0

$0

$0 Total Off-site Benefit

$0

$0

$0

$0

$0

$0 Total Benefit (On-site + Off-site)

$0

$0

$0

$0

$0

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 160 of 173 Table B-4: Seismic Benefit Results for Analysis Cases Case 45 Case 46 Case 47 Case 48 Case 49 Case 09 Case (AC/DC-30R)

(CC-26R)

(OT-10R)

(FW-04)

(CB-10R)

(CB-08)

Off-site Annual Dose (rem) 5.77E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Off-site Annual Property Loss ($)

$8,241

$8,444

$8,444

$8,444

$8,444

$8,444 Comparison CDF 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Comparison Dose (rem) 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 5.91 E+00 Comparison Cost ($)

$8,444

$8,444

$8,444

$8,444

$8,444

$8,444 Enhanced CDF 4.75E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 4.86E-06 Reduction in CDF 2.26%

0.00%

0.00%

0.00%

0.00%

0.00%

Reduction in Off-site Dose 2.37%

0.00%

0.00%

0.00%

0.00%

0.00%

Immediate Dose Savings (On-site)

$9

$0

$0

$0

$0

$0 Long Term Dose Savings (On-site)

$41

$0

$0

$0

$0

$0 Total Accident Related Occupational Exposure (AOE)

$51

$0

$0

$0

$0

$0 Cleanup/Decontamination Savings (On-site)

$1,549

$0

$0

$0

$0

$0 Replacement Power Savings (On-site)

$2,284

$0

$0

$0

$0

$0 Averted Costs of On-site Property Damage (AOSC)

$3,833

$0

$0

$0

$0

$0 Total On-site Benefit

$3,883

$0

$0

$0

$0

$0 Averted Public Exposure (APE)

$3,654

$0

$0

$0

$0

$0 Averted Off-site Damage Savings (AOC)

$2,649

$0

$0

$0

$0

$0 Total Off-site Benefit

$6,303

$0

$0

$0

$0

$0 Total Benefit (On-site + Off-site)

$10,187

$0

$0

$0

$0

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 161 of 173 Table B-4: Seismic Benefit Results for Analysis Cases Case 09 Case (CB-09)

Off-site Annual Dose (rem) 5.91 E+00 Off-site Annual Property Loss ($)

$8,444 Comparison CDF 4.86E-06 Comparison Dose (rem) 5.91 E+00 Comparison Cost ($)

$8,444 Enhanced CDF 4.86E-06 Reduction in CDF 0.00%

Reduction in Off-site Dose 0.00%

Immediate Dose Savings (On-site)

$0 Long Term Dose Savings (On-site)

$0 Total Accident Related Occupational Exposure (AOE)

$0 Cleanup/Decontamination Savings (On-site)

$0 Replacement Power Savings (On-site)

$0 Averted Costs of On-site Property Damage (AOSC)

$0 Total On-site Benefit

$0 Averted Public Exposure (APE)

$0 Averted Off-site Damage Savings (AOC)

$0 Total Off-site Benefit

$0 Total Benefit (On-site + Off-site)

$0

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 162 of 173 Table B-5: Total Benefit Results for Analysis Cases Maximum Case 01 Case 01 Case 01 Case 02 Case 02 Case'O2 Case 03 Benefit (AC/DC-01)

(AC/DC-02)

(AC/DC-03)

(AC/DC-10)

(AC/DC-15)

(AC/DC-16)

(AC/DC-23)

Internal Events -

$500,446

$1,464

$1,464

$1,464

$5,085

$5,085

$5,085

$28,568 Fire

$863,256

$0

$0

$0

$73,012

$73,012

$73,012

$13,860 Seismic

$436,020

$365

$365

$365

$5,144

$5,144

$5,144

$0 Other

$500,446

$1,464

$1,464

$1,464

$5,085

$5,085

$5,085

$28,568 Total Benefit

$2,300,169

$3,294

$3,294

$3,294

-$88,327

$88,327

$88,327

$70,997 Case 04 Case 05 Case 06 Case 07 Case 08 Case 09 Case 09 Case 10 (AC/DC-27)

(AC/DC-28)

(AC/DC-29)

(AT-05)

(AT-07)

(CB-01)

(CB-03)

(CC-01)

Internal Events

$47,920

$1,098

$2,458

$20,328

$0

$10,121

$10,121

$288,908 Fire

$321,712

$4,300

$12,692

$0

$0

$0

$0

$607,051 Seismic

$0

$300

$352

$718

$0

$0

$0

$8,869 Other

$47,920

$1,098

$2,458

$20,328

$0

$10,121

$10,121

$288,908 Total Benefit

$417,553

$6,797

$17,959

$41,375

$0

$20,243

$20,243

$1,193,736

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 163 of 173 Table B-5: Total Benefit Results for Analysis Cases Case 11 Case 12 Case 13 Case 15 Case 18 Case 19 Case 19 Case 20 (CC-02)

(CC-03b)

(CC-20)

(CP-01)

(CW-02)

(CW-03)

(CW-04)

(CW-07)

Internal Events

$288,908

$327

$3,501

$217,779

$56,689

$8,248

$8,248

$54,891 Fire

$607,051

($78)

$378

$576,308

($12,258)

($22,288)

($22,288)

$80,974 Seismic

$8,869

$0

$0

$3,944

$0

$0

$0

$391 Other

$288,908

$327

$3,501

$217,779

$56,689

$8,248

$8,248

$54,891 Total Benefit

$1,193,736

$576

$7,380

$1,015,810

$101,120

($5,792)

($5,792)

$191,148 Case 21 Case 22 Case 22a Case 23 Case 25 Case 26 Case 27 Case 28 (FR-03)

(FR-07a)

(FR-07b)

(HV-02)

(SR-03)

(AT-13)

(AT-14)

(SR-05R)

Internal Events

$0

$0

$0

$1,098

$0

$4,857

$0

$0 Fire

$35,720

$322,694

$31,126

$26

$0

$0

$0

$0 Seismic

$0

$0

$0

$0

$3,096

$0

$0

$57,103 Other

$0

$0

$0

$1,098

$0

$4,857

$0

$0 Total Benefit

$35,720

$322,694

$31,126

$2,221

$3,096

$9,715

$0

$57,103 Case 29 Case 30 Case 31 Case 32 Case 33 Case 34 Case 35 Case 36 (OT-08R)

(FL-05R)

(FL-04R)

(FL-06R)

(CC-24R)

(CC-25R)

(OT-07R)

(FW-05R)

Internal Events

$4,692

$127,374

$128,197

$64,889

$36,357

$3,475

$85,607

$13,367 Fire

$0

$0

$0

$0

$95,184

$4,392

$26,383

$45,084 Seismic

$0

$0

$0

$0

$0

$274

$0

$0 Other

$4,692

$127,374

$128,197

$64,889

$36,357

$3,475

$85,607

$13,367 Total Benefit

$9,385

$254,748

$256,394

$129,777

$167,897

$11,615

$197,597

$71,819

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 164 of 173 Table B-5: Total Benefit Results for Analysis Cases Case 37 Case 38 Case 39 Case 40 Case 41 Case 42 Case 43 Case 44 (FR-09R)

(FR-08)

(AT-15R)

(OT-09R)

(FR-12R)

(FR-11 R)

(FR-10R)

(FL-07R)

Internal Events

$0

$0

$39,864

$21,473

$0

$0

$0

$5,403 Fire

$101,294

$512,974

$0

$87,797

$105,130

$508,730

$13,742

$0 Seismic

$0

$0

$0

$0

$0

$0

$0

$0 Other

$0

$0

$39,864

$21,473

$0

$0

$0

$5,403 Total Benefit

$101,294

$512,974

$79,728

$130,744

$105,130

$508,730

$13,742

$10,805 Case 45 Case 46 Case 47 Case 48 Case 49 Case 09 Case 09 (AC/DC-30R)

(CC-26R)

(OT-1OR)

(FW-04)

(CB-10R)

(CB-08)

(CB-09)

Internal Events

($11,085)

$1,189

$718

$203,081

$9,981

$10,121

$10,121 Fire

$167,910

$3,367

$26

$218,507

$0

$0

$0 Seismic

$10,187

$0

$0

$0

$0

$0

$0 Other

($11,085)

$1,189

$718

$203,081

$9,981

$10,121

$10,121 Total Benefit

$155,927

$5,745

$1,463

$624,669

$19,962

$20,243

$20,243

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 165 of 173 Table B-6: Implementation Cost Estimates Cost Date of Cost Present Day SAMA ID Potential Enhancement Estimate Estimate Estimate (2008)

AC/DO-Ol Provide additional DC battery

$1,730,000 2007

$1,799,200 capacity.

AC/DC-02 Replace lead-acid batteries with 000000 2007

$1,040,000 fuel cells.

$1,,

Add a portable, diesel-driven AC/DC-03 battery charger to existing DC

$500,000 2008

$500,000 system.

AC/DC-10 Provide an additional DG.

$10,000,000 2006

$10,816,000 AC/DC-15 Install a gas turbine generator.

$2,000,000 2007

$2,080,000

>$2,000,000 AC/DC-16 Install tornado protection on gas (cost gas turbine 2007

$2,080,000 6turbine generator.

+ cost tornado protection)

AC/DC-23 Develop procedures to repair or

$375,000 2008

$375,000 replace failed 4 kV breakers.

Install permanent hardware changes that make it possible to AC/DC-27 establish 500kV backfeed

$1,700,000 2008

$1,700,000 through the main set-up transformer.

AC/DC-28 Reduce CCFs between DG-3

$100,000 2008

$100,000 and DG-1/2.

AC/DC-29 Replace DG-3 with a diesel diverse from DG-1 and DG-2.

$4,200,000 2008

$4,200,000 AT-O5 Add an independent boron

$800,000 2008

$800,000 injection system.

Add a system of relief valves to AT-07 prevent equipment damage

$1,000,000 2005

$1,124,864 from pressure spikes during an ATWS.

Automate SLC injection in AT-13 response to ATWS event.

$660,000 2008

$660,000 AT-14 Diversify SLC explosive valve

$370,000 2008

$370,000 operation.

$3000208$7,0 Install an additional pressure or CB-01 leak monitoring instruments for

$5,600,000 2008

$5,600,000 detection of ISLOCAs.

CB-03 Increase leak testing of valves

$400,000 2008

$400,000 in ISLOCA paths.

$4000208$0,0 Revise EOPs to improve ISLOCA identification. The cost CB-08 estimate includes the instrumentation cost (CB-01,

$5,620,000 2008

$5,620,000

$5,600,000) and $20,000 for I revising procedures.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 166 of 173 Table B-6: Implementation Cost Estimates Cost Date of Cost Present Day SAMA ID Potential Enhancement Estimate Estimate Estimate (2008)

Improve operator training on ISLOCA coping. The cost CB-09 estimate includes the

$5,630,000 2008

$5,630,000 instrumentation cost (CB-a01,

$5,600,000) and $30,000 for revising procedures.

Install an independent active or CC-01 passive high pressure injection

$28,000,000 2007

$29,120,000 system.

Provide an additional high CC-02 pressure injection pump with

$5,000,000 2007

$5,200,000 independent diesel.

CC-03b Raise RCIC backpressure trip

$82,000 2008

$82,000 set points.

Improve ECCS suction strainers CC-20 or replace insulation in

$10,000,000 2008

$10,000,000 containment.

GP-01 Install an independent method

$6,000,000 2008

$6,000,000 of SPC.

CW-02 Add redundant DC control

$650,000 2008

$650,000 power for pumps.

CW-03 Replace ECCS pump motors

$1,000,000 2005

$1,124,864 with air-cooled motors.

CW-04 Provide self-cooled ECCS

$675,000 2008

$675,000 seals.

$7,02086500 CW-07 Add a SW pump.

$5,900,000 2007

$6,136,000 FR-03 Install additional transfer and

$2,000,000 2008

$2,000,000 isolation switches.

Improve the fire resistance of FR-07a cables to the containment vent

$400,000 2008

$400,000 valve.

FR-07b Improve the fire resistance of cables to transformer E-TR-S.

$100,000 2008

$100,000 FR-08 Improve thefire-resistance of

$1,250,000 2010

$1,250,000' cables to RHR and SW.

$,500 21$2000 HV-02 Provide a redundant train or

$480,000 2008

$480,000 means of ventilation.

$480,000_2008

$480,000 SR-03 Modify safety related CST.

$980,000 2008

$980,000 SR-05R Improve seismic ruggedness of

$152,000 2010

$152,0001 MCC-7F and MCC-8F.

$152,00I201

$152,000_

OT-08R Install explosion protection

$700,000 2010

$700,0002 around CGS transformers.

$700,000 2010_$700,000 1 This cost estimate was determined in 2010 in response to a RAI from the NRC.

was used in the cost-benefit analysis for SAMA candidates FR-08 and SR-05R.

The 2010 cost estimate

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 167 of 173 Table B-6: Implementation Cost Estimates Cost Date of Cost Present Day SAMA ID Potential Enhancement Estimate Estimate Estimate (2008)

Install clamp-on flow instruments to certain drain lines FL-05R in the Control Building area of

$250,000 2010

$250,0002 the Radwaste Building with alarms in the Control Room.

Add one isolation valve in the FL-04R SW, TSW, and FP lines in the

$377,000 2010

$377,0002 Control Building area of the Radwaste Building.

Perform additional NDE and inspections of the SW, TSW, FL-06R and FP lines in the Control

$13,500 2010

$13,5002 Building area of the Radwaste Building.

Backfeed the HPCS system with CC-24R SM-8 to provide a third power

$105,000 2010

$105,0002 source for HPCS.

Enhance alternate injection CC-25R reliability by including RHRSW

$13,000 2010

$13,0002 and fire water cross-tie in the maintenance program.

Improve procedures and operator training to identify OT-07R systems and operator actions

$40,000 2010

$40,0002 determined to be important from the PSA.

Examine the potential for FW-05R operators to control RFW and

$29,000 2010

$29,0002 avoid a reactor trip.

Install early fire detection in the FR-09R following Reactor Building

$680,000 2010

$680,0002 analysis units: R-1 B, R-1 D, and R-1J.

Install modifications to make AT-15R use of HPCS more likely for

$2,825,000 2010

$2,825,0002 ATWS.

For the non-LOCA initiating OT-09R events, credit the Z (PCS

$130,000 2010

$130,0002 recovery) function.

Install early fire detection in the FR-12R following physical analysis units:

$725,000 2010

$725,000' T-1A, T-12, T-1C, and T-1D.

I I

2 This cost estimate was determined in 2010 in response to a request for additional information (RAI) from the NRC. The 2010 cost estimate was used in the cost-benefit analysis for SAMA candidates OT-08R, FL-05R, FL-04R, FL-06R, CC-24R, CC-25R, OT-07R, FW-05R, FR-09R, AT-15R, and OT-09R.

3 This cost estimate was determined in 2010 in response to a request for additional information (RAI) from the NRC. The 2010 cost estimate was used in the cost-benefit analysis for SAMA candidates FR-12R, FR-11 R, FR-1 OR, FL-07R, AC/DC-30R, CC-26R, OT-1OR, FW-04, and CB-1 OR.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 168 of 173 Table B-6: Implementation Cost Estimates Cost Date of Cost Present Day SAMA ID Potential Enhancement Estimate Estimate Estimate (2008)

Install early fire detection in the following analysis units: RC-02, FR-i 1 R RC-03, RC-04, RC-05, RC-07,

$1,035,000 2010

$1,035,0003 RC-08, RC-11, RC-13, RC-14, and RC-1A.

FR-i OR Install early fire detection in the

$535,000 2010

$535,000' Main Control Room: RC-10.

FL-07R Protect the HPCS from flooding

$1,050,000 2010

$1,050,000' FL-07R_____

resulting from ISLOCA events.

$1000021_10000 AC/DC-30R Provide an additional DG 3

diverse from DG-1 and DG-2.

$10,000,000 2010

$10,000,000 CC-26R Install hard pipe from diesel fire

$710,000 2010

$710,000 pump to vessel.

Increase fire pump house building integrity to withstand OT-1OR higher winds so the fire system

$735,000 2010

$735,0003 will be capable of withstanding a severe weather event.

FW-04 Add a motor-driven feedwater

$10,000,000 2010

$10,000,0003 pump.

Provide additional NDE and

,CB-10R inspections of MS pipe in

$125,000 2010

$125,000' 1 Turbine Building.

I I

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 169 of 173 Table B-7: Final Results of the Cost-Benefit Evaluation SAMD ID Modification Analysis Estimated Cost of Conclusion Case Benefit Implementation AC/DC-01 Provide additional DC battery capacity.

Case 01

$3,294

$1,799,200 Not Cost Effective AC/DC-02

-Replace lead-acid batteries with fuel cells.

Case 01

$3,294

$1,040,000 Not Cost Effective AC/DC-03 Add a portable, diesel-driven battery charger to existing DC Case 01

$3,294

$500,000 Not Cost Effective system.

AC/DC-10 Provide an additional DG.

Case 02

$88,327

$10,816,000 Not Cost Effective AC/DC-15 Install a gas turbine generator.

Case 02

$88,327

$2,080,000 Not Cost Effective AC/DC16 Install tornado protection on gas turbine generator.

Case 02

$88,327

$2,080,000 Not Cost Effective AC/DC-23 Develop procedures to repair or replace failed 4 KV -

Case 03

$70,997

$375,000 Not Cost Effective breakers.

Install permanent hardware changes that make it possible to AC/DC-27 establish 500 kV backfeed through the main set-up Case 04

$417,553

$1,700,000 Not Cost Effective transformer.

AC/DC-28 Reduce CCFs between DG-3 and DG-1/2.

Case 05

$6,797

$100,000 Not Cost Effective AC/DC-29 Replace DG-3 with a diesel diverse from DG-1 and DG-2.

Case 06

$17,959

$4,200,000 Not Cost Effective AT-05 Add an independent boron injection system.

Case 07

$41,375

$800,000 Not Cost Effective AT-07 Add a system of relief valves to prevent equipment damage Case 08

$0

$1,124,864 Not Cost Effective from pressure spikes during an ATWS.

AT-1 3 Automate SLC injection in response to ATWS event.

Case 26

$9,715

$660,000 Not Cost Effective.

AT-14 Diversify SLC explosive valve operation.

Case 27

$0

$370,000 Not Cost Effective CB-01 Install an additional pressure or leak monitoring instruments Case 09

$20,243

$5,600,000 Not Cost Effective for detection of ISLOCAs.

CB-03 Increase leak testing of valves in ISLOCA paths.

Case 09

$20,243

$400,000 Not Cost Effective CB-08 Revise EOPs to improve ISLOCA identification.

Case 09

$20,243.

$5,620,000 Not Cost Effective CB-09 Improve operator training on ISLOCA coping.

Case 09

$20,243

$5,630,000 Not Cost Effective CC-01 Install an independent active or passive high pressure Case 10

$1,193,736

$29,120,000 Not Cost Effective injection system.

CC-02 Provide an additional high pressure injection pump with Case 11

$1,193,736

$5,200,000 Not Cost Effective independent diesel.

CC-03b Raise RCIC backpressure trip set points.

Case 12

$576

$82,000 Not Cost Effective

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 170 of 173 Table B-7: Final Results of the Cost-Benefit Evaluation Analysis Estimated Cost of Conclusion SAMD ID Modification Case Benefit Implementation CC-20 Improve EGGS suction strainers or replace insulation in Case 13

$7,380

$10,000,000 Not Cost Effective containment.

CP-01 Install an independent method of SPC.

Case 15

$1,015,810

$6,000,000 Not Cost Effective CW-02 Add redundant DC control power for pumps.

Case 18

$101,120

$650,000 Not Cost Effective Not a viable SAMA CW-03 Replace EGGS pump motors with air-cooled motors.

Case 19

($5,792)

$1,124,864 candidate.

Not a viable SAMA CW-04 Provide self-cooled ECCS seals.

Case 19

($5,792)

$675,000 candidate.

CW-07 Add a SW pump.

Case 20

$191,148

$6,136,000 Not Cost Effective FR-03 Install additional transfer and isolation switches.

Case 21

$35,720

$2,000,000 Not Cost Effective FR-07a Improve the fire resistance of cable to the containment vent Case 22

$322,694

$400,000 Not Cost Effective valve.

FR-07b Improve the fire resistance of cable to transformer E-TR-S.

Case 22a

$31,126

$100,000 Not Cost Effective FR-08 Improve the fire resistance of cables to RHR and SW.

Case 38

$512,974

$1,250,000 Not Cost Effective HV-02 Provide a redundant train or means of ventilation.

Case 23

$2,221

$480,000 Not Cost Effective SR-03 Modify safety-related CST.

Case 25

$3,096

$980,000 Not Cost Effective SR-05R Improve seismic ruggedness of MCC-7F and MCC-8F.

Case 28

$57,103

$152,000 Not Cost Effective OT-08R Install explosion protection around CGS transformers.

Case 29

$9,385

$700,000 Not Cost Effective Install clamp-on flow instruments to certain drain lines in the FL-05R Control Building area of the Radwaste Building with alarms in Case 30

$254,748

$250,000 Cost Effective the Control Room.

FL-04R Add one isolation valve in the SW, TSW, and FP lines in the Case 31

$256,394

$377,000 Not Cost Effective Control Building area of the Radwaste Building.

Perform additional NDE and inspections of the SW, TSW, FL-06R and FP lines in the Control Building area of the Radwaste Case 32

$129,777

$13,500 Cost Effective Building.

CC-24R Backfeed the HPCS system with SM-8 to provide a third Case 33

$167,897

$105,000 Cost Effective power source for HPCS.

I I

CC-25R Enhance alternate injection reliability by including RHRSW Case 34

$11,615

$13,000 Not Cost Effective I and fire water cross-tie in the maintenance program.

I

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 171 of 173 Table B-7: Final Results of the Cost-Benefit Evaluation SAMD ID Modification Analysis Estimated Cost of Conclusion Case Benefit Implementation Improve procedures and operator training to identify systems OT-07R and operator actions determined to be important from the Case 35

$197,597

$40,000 Cost Effective PSA.

FW-05R Examine the potential for operators to control RFW and Case 36

$66,860

$29,000 Cost Effective avoid a reactor trip.

FR-09R Install early fire detection in the following Reactor Building Case 37

$101,294

$680,000 Not Cost Effective analysis units: R-1B, R-1D, and R-1J.

AT-15R Install modifications to make use of HPCS more likely for Case 39

$79,728

$2,825,000 Not Cost Effective ATWS.

OT-09R For the non-LOCA initiating events, credit the Z (PCS Case 40

$130,744

$130,000 Cost Effective recovery) function.

FR-12R Install early fire detection in the following physical analysis Case 41

$105,130

$725,000 Not Cost Effective units: T-1A, T-12, T-1C, and T-1D.

Ce$5370N otfi Install early fire detection in the following analysis units: RC-FR-11 R 02, RC-03, RC-04, RC-05, RC-07, RC-08, RC-1 1, RC-1 3, Case 42

$508,730

$1,035,000 Not Cost Effective RC-14, and RC-1A.

FR-1 OR Install early fire detection in the Main Control Room: RC-10.

Case 43

$13,742

$535,000 Not Cost Effective FL-07R Protect the HPCS from flooding resulting from ISLOCA Case 44

$10,805

$1,050,000 Not Cost Effective events.

AC/DC-30R Provide an additional DG diverse from DG-1 and DG-2.

Case 45

$155,927

$10,000,000 Not Cost Effective CC-26R Install hard pipe from diesel fire pump to vessel.

Case 46

$5,745

$710,000 Not Cost Effective Increase fire pump house building integrity to withstand OT-1 OR higher winds so the fire system will be capable of Case 47

$1,463

$735,000 Not Cost Effective withstanding a severe weather event.

FW-04 Add a motor-driven feedwater pump.

Case 48

$624,669

$10,000,000 Not Cost Effective CB-1OR Provide additional NDE and inspections of MS pipe in Case 49

$19,962

$125,000 Not Cost Effective Turbine Building.

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 172 of 173 Table B-8: Final Results of the Sensitivity Cases SAMA ID Sensitivity Sensitivity Estimated Conclusion Case #1 Case #21 Cost (2008/2010)

AC/DC-01

$4,338

$8,125

$1,799,200 Not Cost Effective AC/DC-02

$4,338

$8,125

$1,040,000 Not Cost Effective AC/DC-03

$4,338

$8,125

$500,000 Not Cost Effective AC/DC-10

$124,168

$229,673

$10,816,000 Not Cost Effective AC/DC-15

$124,168

$229,673

$2,080,000 Not Cost Effective AC/DC-16

$124,168

$229,673

$2,080,000 Not Cost Effective AC/DC-23

$103,456

$173,164

$375,000 Not Cost Effective AC/DC-27

$597,972

$1,066,469

$1,700,000 Not Cost Effective AC/DC-28

$9,022

$17,353

$100,000 Not Cost Effective AC/DC-29

$23,879

$45,853

$4,200,000 Not Cost Effective AT-05

$64,739

$99,730

$800,000 Not Cost Effective AT-07

$0

$0

$1,124,864 Not Cost Effective AT-1 3

$14,999

$23,315

$660,000 Not Cost Effective AT-14

$0

$0

$370,000 Not Cost Effective CB-01

$30,499

$48,582

$5,600,000 Not Cost Effective CB-03

$30,499

$48,582

$400,000 Not Cost Effective CB-08

$30,499

$48,582

$5,620,000 Not Cost Effective CB-09

$30,499

$48,582

$5,630,000 Not Cost Effective CC-01

$1,709,802

$2,991,699

$29,120,000 Not Cost Effective CC-02

$1,709,802

$2,991,699

$5,200,000 Not Cost Effective CC-03b

$673

$1,366

$82,000 Not Cost Effective CC-20

$10,840

$17,788

$10,000,000 Not Cost Effective CP-01

$1,511,838

$2,555,573

$6,000,000 Not Cost Effective CW-02

$136,498

$240,236

$650,000 Not Cost Effective CW-03

($20,934)

($18,357)

$1,124,864 Not Cost Effective CW-04

($20,934),

($18,357)

$675,000 Not Cost Effective CW-07

$270,705

$475,184

$6,136,000 Not Cost Effective FR-03

$47,994

$92,873

$2,000,000 Not Cost Effective FR-07a

$477,812

$839,005

$400,000 Cost Effective-Sensitivity Cases 1 & 2 FR-07b

$46,023

$80,926

$100,000 Not Cost Effective FR-08

$743,114

$1,333,731

$1,250,000 Cost Effective-Sensitivity Case 2 HV-02

$3,122

$5,336

$480,000 Not Cost Effective SR-03

$4,574

$9,287

$980,000 Not Cost Effective SR-05R

$82,084

$171,310

$152,000 Cost Effective-Sensitivity Case 2 OT-08R

$12,471

$22,524

$700,000 Not Cost Effective FL-05R

$388,192

$611,395

$250,000 Cost Effective

SENSITIVITY STUDY BASED UPON THE INTEGRATED PSA MODEL REV. 7.1 Page 173 of 173 Table B-8: Final Results of the Sensitivity Cases SAMA ID Sensitivity Sensitivity Estimated Conclusion Case #1 Case #21 Cost (2008/2010)

FL-04R

$390,642

$615,345

$377,000 Cost Effective-Sensitivity Cases 1 & 2 FL-06R

$197,662

$311,465

$13,500 Cost Effective CC-24R

$244,548

$421,991

$105,000 Cost Effective CC-25R

$16,457

$28,919

$13,000 Cost Effective - Sensitivity Cases 1 & 2 OT-07R

$264,720

$479,509

$40,000 Cost Effective FW-05R

$99,445

$181,382

$29,000 Cost Effective FR-09R

$138,485

$263,365

$680,000 Not Cost Effective AT-1 5R

$101,544

$191,348

$2,825,000 Not Cost Effective OT-09R

$193,609

$331,346

$130,000 Cost Effective FR-12R

$150,512

$273,337

$725,000 Not Cost Effective FR-i 1 R

$736,493

$1,322,699

$1,035,000 Cost Effective - Sensitivity Case 2 FR-10R

$19,989

$35,730

$535,000 Not Cost Effective FL-07R

$17,942

$25,933

$1,050,000 Not Cost Effective AC/DC-30R

$225,380

$413,919

$10,000,000 Not Cost Effective CC-26R

$8,973

$14,461

$710,000 Not Cost Effective OT-1 OR

$2,146

$3,516

$735,000 Not Cost Effective FW-04

$904,245

$1,542,907

$10,000,000 Not Cost Effective CB-1OR

$28,619

$47,910

$125,000 Not Cost Effective 1 The replacement power component for Sensitivity Case 1 (3% Discount Rate) is calculated using the replacement power net present value for a 1% and 5% discount rate and interpolating for the 3%

discount rate.

5 Columbia Generating Station License Renewal Application Environmental Report Table E.4-4 Fire LERF Contribution for Each Plant Damage State (continued)

LERF Total LERF PDS Description PDS Split Contribution Frequency Fraction (per year)

LOOP sequences with no high or low pressure injection, but RPV depressurization is successful.

11HB This results in core damage before containment 7.7E-8 7.8E-4 5.97E-1 1 failure, with the reactor at low pressure. HPCS is not recoverable.

Transient with stuck-open SRV or LOCA with loss 2B of containment heat removal. Containment failure 2.8E-8 0.0 c.0E+0 occurs prior to core damage with the reactor vessel

~ ~~~....*4.w.l:.

A04;stu-We*

A-_A,¢_.¢..*..¢_..._¢&F.-.¢_.._...._.._.

cof cntainment hfat ilmed

-l.

Ccntainmcnt fci'-r6 Transient with loss of containment heat unmovaer.

42BD C ontainm ent fails prior to core dam age w ith the n/aQ44 0.O E +0 reactor vessel at high pressure.

11.5E-6ne w

a.0f ATWS with vessel intact at tim e ow re uncovery, 43A which indicates high pressure core damage with 2.7E-10 1.0 2.7E-10 containment failed.

ATWS with vessel failed at time of core uncovery, 4131 which indicates low pressure core damage with 0.0E+0 n/a 0.0E+0 containment failed.

LOCA outside containment with failure to isolate 5

the break. The sequences indicate low reactor 0.0E+0 n/a 0.0E+0 pressure at the time of core damage, with the containment bypassed.

SBO sequences with early failure of HPCS and RCIC. The sequences indicate high reactor 6AIA pressure at the time of core damage, with the 0.0E+0 n/a 0.0E+0 containment intact. HPCS is recoverable after core damage occurs.

SBO sequences with early failure of HPCS and 6Ai B RClC. The sequences indicate high reactor 3.7E-7 6.8E-2 2.5E-8 pressure'at the time of core damage, with the containment intact. HPCS is not recoverable.

SBO sequences with a SORV, no containment heat removal, but successful injection until containment 6A2 failure. Injection fails at containment failure, 7.6E-8 0.0 0.OE+0 resulting in core damage at low reactor pressure with containment failed.

SBO sequences with initial success of HPCS. If HPCS operation is lost due to HPCS diesel failure, 6B1 operation is recoverable if AC power is restored.

2.7E-7 0.0 0.0E+0 Containment heat removal is unavailable. Core damage occurs at high pressure with containment I intact.

I I

I Attachment E Page E-107 Attachment E Page E-107 JAmendment 24

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