ML113540354

Environmental Report; Operating License Renewal Stage Final, Attachment E Through End

ML113540354
Person / Time
Site:	Callaway
Issue date:	12/15/2011
From:	Ameren Missouri
To:	Office of Nuclear Reactor Regulation
Shared Package
ML113530374	List: ML113530372 ML113540349 ML113540354 ULNRC-05830, Application for Renewed Operating License (LDCN 11-0022)
References
ULNRC-05830
Download: ML113540354 (127)

Text

Attachment E Microbiological Correspondence ATTACHMENT E MICROBIOLOGICAL CORRESPONDENCE Letter Page Brian F. Holderness, Ameren to Lisa Schutzenhofer, MDH ...................................................... E-2 Cherri Baysinger, MDH to Brian F. Holderness, Ameren .......................................................... E-7 Brian F. Holderness, Ameren to Kevin Mohammadi, MDNR .................................................... E-9 John Ford, MDNR to Brian F. Holderness, Ameren ................................................................ E-14 Callaway Plant Unit 1 Environmental Report for License Renewal E-1

Attachment E Microbiological Correspondence Amtn SeIce3 OneAmeren Plaza 1901 Chouteau Avenue EnvironmenzalSerwice.s P° Box 66149 314.554.3574 (Phone) LOUIS, MO 63166-6149 314S54.4182 (Facsimile) 314$21.3m bho1derqess(ameren.com April 15, 2010 Ms. Lisa Schutzenhofer Bureau of Communicable Disease Control & Prevention Missouri Department of Health & Senior Services P0 Box 570 City, Missouri 65102 Jefferson I 411181V11

SUBJECT:

Callaway Unit 1 License Renewal, Request for Information on Thermophilic Microorganisms

Dear Ms. Schutzenhofer:

AmerenUE Corporation (AmerenUE) is preparing an application to the U.S.

Nuclear Regulatory Commission (NRC) to renew the operating license for Callaway Unit 1 (Callaway Nuclear Plant). The current operating license for Callaway Nuclear Plant will expire on October 18, 2024. Renewing the license would provide for an additional 20 years of operation beyond this license expiration date. The NRC requires license applicants to provide ... an assessment of the impact of the proposed action [license renewal] on public health from thermophilic organisms in the affected water (10 CFR 51.53). Organisms of concern include the enteric pathogens Salmonella and Shigella, the Pseudomonas aeruginosa bacterium, thermophilic Actinomycetes (fungi), the many species of Legionella bacteria, and pathogenic strains of the free-living Naegleria amoeba.

As part of the license renewal process, AmerenUE is consulting with your office to determine whether there is any concern about the potential occurrence of these organisms in the Missouri River in the area of the Callaway plant. By contacting you early in the application process, we hope to identify any issues that we need to address or any information that we should provide to your office to expedite the NRC consultation.

AmerenUB (formerly known as Union Electric Company) has operated Callaway Nuclear Plant since 1984. The Callaway Plant is located in Callaway County, Missouri, approximately 10 miles southeast of the town of Fulton and five miles north of the Missouri River (see attached Figure 1). The Plant employs closed-cycle cooling, with a large natural-draft cooling tower dissipating waste heat from the circulating water system. Makeup water for the cooling tower is withdrawn from the Missouri River at an intake structure located at River Mile 115.4.

Cooling tower blowdown is discharged a short but sufficient distance downstream Callaway Plant Unit I Environmental Report for License Renewal E-2

Attachment E Microbiological Correspondence from the intake structure to ensure that there is no recirculation of heated water (see attached Figure 2). The maximum volume of blowdown discharged to the Missouri River (approximately 1 1 cfs), is extremely small compared to the normal flow of the Missouri River (approximately 70,000 cfs, on average), illustrating how little impact this blowdown has on river temperatures.

Callaway Power Plants National Pollutant Discharge Elimination System (NPDES) permit (MO-0098001), which has an effective date of February 13, 2009 requires daily monitoring of blowdown (Outfall 002) temperatures before discharge into the Missouri River. A review of Discharge Monitoring Reports submitted to Missouri DNR in the third quarter of 2007, 2008, and 2009 showed blowdown temperatures in late summer (July-AugustSeptember) ranging from 73.5° to 98°F. The hihest temperatures measured over this three-year period were recorded on August 4 and 5 a, 2008. Water temperatures between 73F and 98SF are well below the optimal temperature range (122T-l4tYF) for growth and reproduction of thermophilic microorganisms. And, as noted previously, the Callaway Plants discharge (blowdown) has very little effect on ambient water temperatures.

We would appreciate hearing from you by June 10, 2010, on any concerns you may have about these organisms. Please state potential public health effects over the license renewal term or your confirmation of AsnerenUEs conclusion that operation of the Callaway Plant over the license renewal term would not stimulate growth of thermophilic pathogens in the Missouri River. This will enable us to meet our application preparation schedule. ArnerenUE will include a copy of this letter and your response in the Environmental Report that will be submitted to the NRC as part of the Callaway license renewal application.

Please do not hesitate to contact me if you have any questions or require any additional information.

Sincerely, Brian F. Holderness Senior Environmental Health Physicist

Enclosure:

Figure 1, Figure 2 Callaway Plant Unit I Environmental Report for License Renewal E-3

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Attachment E Microbiological Correspondence Missouri Department of Health and Senior Services P.O. Box 570, Jefferson City, MO 65102-0570 Phone: 573-751-6400 FAX: 573-7516O1O RELAY MISSOURI for Hearing and Speech Impaired 1-800-735-2966 VOICE 1-800-735-2466 Margaret T. Donnelly Jeremiah W. (Jay) Nixon Director Governor November 1, 2010 Mr. Brian F. Holderness Senior Environmental Health Physicist Ameren Services One Ameren Plaza 1901 Chouteau Avenue P0 Box 66149 St. Louis, MO 63166-6149

Dear Mr. Holderness:

We have reviewed the Callaway Unit I License Renewal, Request for Information on Thermophilic Microorganisms dated April 15, 2010. This document states that AmerenUE is consulting with your office (Missouri Department of Health and Senior Services) to determine whether there is any concern about the potential occurrence of these organisms in the Missouri River in the area of the Callaway plant.

In the subject heading of the letter, thermophilic microorganisms are specifically mentioned. However, within the text, other organisms are mentioned such as Pseudomonas aeruginosa, Legionella, and Naegleria amoeba.

It is our understanding ofthis letter that you would like to receive our input as to whether or not there is a potential concern that a significant number of any of these organisms may enter the Missouri River through the power plants discharge system. This discharge system begins at the cooling tower and then travels below ground for approximately 5 miles before it discharges into the Missouri River. It is our understanding that the water temperature in the cooling tower is consistently 90° F to 100° F. The letter you sent us states that the water is between 73.5° F and 98° F when it is discharged into the Missouri River.

We agree that the temperatures ofthe water in the cooling tower and throughout the discharge system are not optimal for most thermophilic microorganisms. This would eliminate the likelihood of many of these organisms occurring in the system and therefore being discharged into the river. However, some Naegleria species are thermophilic. The growth range ofthese thermophilic amoebae is cited as being 25°C to 50°C (77°F to 122°F). The temperature range ofthese amoebae overlaps the temperature range of the cooling tower and discharge. Thus, the presence of these microorganisms in the system cannot be ruled out based solely on temperature.

Further, the conditions in the cooling towerand discharge are favorable for establishment and growth of other microorganisms. One organism that is known to exist in cooling towers in general is Legionella.

At this time, there is no reason we know of why a microorganism, such as Legionella, could not exist in www.dhss.mo.gov Healthy Missourians for life.

The Missouri Department of Health and Senior Services will be the leader in promoting, protecting and partnering for health.

AN EQUAL OPPORTUNITY I AFFIRMATIVE ACTION EMPLOYER: Services provided on a nondiscriminatory basis.

Callaway Plant Unit I Environmental Report for License Renewal E-7

Attachment E Microbiological Correspondence Mr. Brian Holderness June 21, 2010 Page 2 of 2 this system. We also do not know of anything in the system that would prevent these microorganisms from entering the Missouri River through the discharge system.

At this time, we do not have enough information to accurately make a conclusion on the wide range of microorganisms mentioned in the letter. We would be happy to review this further if you can provide additional information that would better allow us to draw a more definitive conclusion. This information may include reasons why microorganisms would not live and thrive in the cooling tower or discharge pipe and/or be present in the discharge prior to entering the river. If you have any questions, please contact Jeff Wenzel at (573) 751-6102.

Sincerely, Cherri Baysinger, Chief Bureau of Environmental Epidemiology CB/JG/J W/mp Callaway Plant Unit I Environmental Report for License Renewal E-8

Attachment E Microbiological Correspondence Amerea Sewc One Ajneren Plaza 1901 Chouteau Avenue EnvironmenlalServices P0 Box66149 314.5543574 (Phone) St. Louis, MO 63166-6149 314354.4182 (Facsimile) 3144213w bhoIdernessinzeren.com April 15, 2010 Mr. Kevin Mohanimadi Missouri Dept. of Natural Resources Water Pollution Control Branch P.O. Box 176 Jefferson City, Missouri 65102 V

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SUBJECT:

Callaway Unit 1 License Renewal, Request for Information on Thermophilic Microorganisms

Dear Mr. Mohammadi:

AmerenUE Corporation (AmerenUE) is preparing an application to the U.S.

Nuclear Regulatory Commission (NRC) to renew the operating license for Callaway Unit 1 (Callaway Nuclear Plant). The current operating license for Callaway Nuclear Plant will expire on October 18, 2024. Renewing the license would provide for an additional 20 years of operation beyond this license expiration date, The NRC requires license applicants to provide ... an assessment of the impact of the proposed action (license renewal] on public health from thermophilic organisms in the affected water (10 CFR 51.53). Organisms of concern include the enteric pathogens Salmonella and Shigella, the Pseudomonas aeruginosa bacterium, thermophilic Actinomycetes (fungi), the many species of Legionella bacteria, and pathogenic strains of the free-living Naegleria amoeba.

As part of the license renewal process, AmerenUE is consulting with your office to determine whether there is any concern about the potential occurrence of these organisms in the Missouri River in the area of the Callaway plant. By contacting you early in the application process, we hope to identify any issues that we need to address or any information that we should provide to your office to expedite the NRC consultation.

AmerenUE (formerly known as Union Electric Company) has operated Callaway Nuclear Plant since 1984. The Callaway Plant is located in Callaway County, Missouri, approximately 10 miles southeast of the town of Fulton and five miles north of the Missouri River (see attached Figure 1). The Plant employs closed-cycle cooling, with a large natural-draft cooling tower dissipating waste heat from the circulating water system. Makeup water for the cooling tower is withdrawn from the Missouri River at an intake structure located at River Mile 115.4.

Cooling tower blowdown is discharged a short but sufficient distance downstream SS iayoArr,eri Callaway Plant Unit I Environmental Report for License Renewal E-9

Attachment E Microbiological Correspondence from the intake structure to ensure that there is no recirculation of heated water (see attached Figure 2). The maximum volume of blowdown discharged to the Missouri River (approximately 11 cfs), is extremely small compared to the normal flow of the Missouri River (approximately 70,000 cfs, on average), illustrating how little impact this hiowdown has on river temperatures.

Callaway Power Plants National Pollutant Discharge Elimination System (NPDES) permit (MO-0098001), which has an effective date of February 13, 2009 requires daily monitoring of blowdown (Outfall 002) temperatures before discharge into the Missouri River. A review of Discharge Monitoring Reports submitted to Missouri DNR in the third quarter of 2007, 2008, and 2009 showed blowdown temperatures in late summer (July-August-September) ranging from 7350 to 98°F. The hihest temperatures measured over this three-year period were recorded on August 4 and 5 th, 2008. Water temperatures between 73F and 98F are well below the optimal temperature range (122F440F) for growth and reproduction of thermophilic microorganisms. And, as noted previously, the Callaway Plants discharge (blowdown) has very little effect on ambient water temperatures.

We would appreciate hearing from you by June 10, 2010, on any concerns you may have about these organisms. Please state potential public health effects over the license renewal term or your confirmation of AmerenUEs conclusion that operation of the Callaway Plant over the license renewal term would not stimulate growth of thermophilic pathogens in the Missouri River. This will enable us to meet our application preparation schedule. AmerenUE will include a copy of this letter and your response in the Environmental Report that will be submitted to the NRC as part of the Callaway license renewal application.

Please do not hesitate to contact me if you have any questions or require any additional information.

Sincerely, Brian F. Holderness Senior Environmental Health Physicist

Enclosure:

Figure 1, Figure 2 Callaway Plant Unit I Environmental Report for License Renewal E-I 0

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&i vwanr.mo.gov April 22, 2010 Mr. Brian Holderness Senior Environmental Health Physicist Ameren One Ameren Plaza 1901 Chouteau Avenue, P.O. Box 66149 St. Louis, MO 63166-6149

Dear Mr. Holderness:

I am writing in response to your letter ofApril 15, 2010 asking ifthe Department of Natural Resources had any concerns about thermophilic microorganisms in the Missouri River near the Callaway Power Plant. We do.

The Department is the regulatory agency responsible for protection ofwater quality in Missouri and enforcement of state and federal clean water laws. We recently modified our state water quality standards (10 CSR 20-7.031) to include whole body contact recreation as a beneficial use on all ofthe Missouri River. We use the results ofE. co/i tests to judge whether or not there is an unacceptably high risk ofwaterbome disease for swimmers or others that may become fully immersed in the water, and we have E. co/i data from several locations on the Missouri River. Data from the lower portion of the river, from Hermann to the mouth generally fails to meet our standards for whole body contact recreation, and thus is an area of concern.

However, we do not have any E. coli data from the portion ofthe river immediately downstream of the Callaway discharge, and thus do not know if this section of the river contains greater concentrations of microorganisms and thus a greater risk of waterbome disease.

While generally considered good indicators ofwaterborne disease risk, E. coli are probably not good indicators ofthe full range ofthennophilic microorganisms, some of which are free living forms. E. co/i are non-pathogenic enteric bacteria and are used as indicators of fecal contamination of the water and the likely presence of pathogenic enteric bacteria such as Salmonella and Shigella. TheE. coli test does not confirm the presence of specific pathogenic enteric bacteria nor does it provide a quantitative estimate of the numbers of specific pathogenic bacteria. TheE. co/i test would likewise not be considered a good indicator of free-livings microorganisms such as Pseudomonas aeruginosa or Naegleria amoeba.

RPp Callaway Plant Unit I Environmental Report for License Renewal E-14

Attachment E Microbiological Correspondence Mr. Brian Holderness Page Two To summarize, there are elevated levels ofE. coli bacteria in the lower Missouri River, and there are substantial limitations on the ability ofthe E. coil test to characterize the full range ofpathogenic thermophilic microorganisms that may be present in the river.

Adding the possibility that the Callaway plant site and discharge may create environments more suitable for free living thermophilic microorganisms than are found in most other portions of the river, the Department cannot conclude that this section of the Missouri does not pose a significant risk of waterborne disease.

If you have any further questions, please do not hesitate to call me at (573) 751-7024 or email me at john.fordi2dnr.mo.gpv.

Sincerely, WATER PROT TION PROGRAM Jo1tMef Water Quality Assessment Unit JF/lsm Callaway Plant Unit I Environmental Report for License Renewal E-15

Attachment F Severe Accident Mitigation Alternatives ATTACHMENT F SEVERE ACCIDENT MITIGATION ALTERNATIVES

Attachment F Severe Accident Mitigation Alternatives EXECUTIVE

SUMMARY

This report provides an analysis of the Severe Accident Mitigation Alternatives (SAMAs) that were identified for consideration by the Callaway Station. This analysis was conducted on a cost/benefit basis. The benefit results are contained in Section 4 of this report. Candidate SAMAs that do not have benefit evaluations have been eliminated from further consideration for any of the following reasons:

• The cost is considered excessive compared with benefits.

• The improvement is not applicable to Callaway Plant.

• The improvement has already been implemented at Callaway Plant or the intended effect of the improvement has already been achieved for Callaway Plant.

After eliminating a portion of the SAMAs for the preceding reasons, the remaining SAMAs are evaluated from a cost-benefit perspective. In general, the evaluation examines the SAMAs from a bounding analysis approach to determine whether the expected cost would exceed a conservative approximation of the actual expected benefit.

Major insights from this benefit evaluation process included the following:

• If all severe accident risk is eliminated, then the benefit in dollars over 20 years is

$3,192,773.

• The largest contributors to the total benefit estimate are from onsite dose savings and onsite property costs including replacement power.

• A large number of SAMAs had already been addressed by existing plant features, modifications to improve the plant, existing procedures, or procedure changes to enhance human performance.

• Three SAMAs were identified as potentially cost-beneficial and are described in the following table.

Callaway Plant Unit 1 Environmental Report for License Renewal F-1

Attachment F Severe Accident Mitigation Alternatives Callaway Plant Potentially Cost Beneficial SAMAs Callaway SAMA Number Potential Improvement Discussion Additional Discussion 29 Provide capability for Improved injection Currently being evaluated alternate injection via diesel- capability. by plant improvement driven fire pump. program. Would use unborated water and portable pump (fire truck).

Calculation of specific benefit of this SAMA was not performed since it is judged to be potentially low cost. Evaluation will consider impacts of injection of non-borated water.

160 Modifications to lessen Lower impact of flood that impact of internal flooding propagates through the path through Control dumbwaiter Building dumbwaiter.

162 Install a large volume Allows transfer of EDG fuel Emergency Diesel oil to the EDG day tanks on Generator (EDG) fuel oil failure of the fuel oil transfer tank at an elevation greater pumps.

than the EDG fuel oil day tanks.

Callaway Plant Unit 1 Environmental Report for License Renewal F-2

Attachment F Severe Accident Mitigation Alternatives TABLE OF CONTENTS Section Page EXECUTIVE

SUMMARY

........................................................................................................ F-1 ACRONYMS USED IN ATTACHMENT F................................................................................ F-5

1.0 INTRODUCTION

......................................................................................................... F-8 1.1 PURPOSE ............................................................................................................... F-8 1.2 REQUIREMENTS .................................................................................................... F-8 2.0 METHOD..................................................................................................................... F-8 3.0 SEVERE ACCIDENT RISK ....................................................................................... F-10 3.1 LEVEL 1 PRA MODEL .......................................................................................... F-10 3.1.1 Internal Events ............................................................................................... F-10 3.1.2 External Events .............................................................................................. F-21 3.2 Level 2 PSA Model Changes Since IPE Submittal ................................................. F-22 3.3 Model Review Summary ........................................................................................ F-32 3.4 LEVEL 3 PRA MODEL .......................................................................................... F-33 3.4.1 Population Distribution ................................................................................... F-34 3.4.2 Economic Data .............................................................................................. F-37 3.4.3 Nuclide Release ............................................................................................. F-38 3.4.4 Emergency Response .................................................................................... F-46 3.4.5 Meteorological Data ....................................................................................... F-46 3.5 SEVERE ACCIDENT RISK RESULTS .................................................................. F-47 4.0 COST OF SEVERE ACCIDENT RISK / MAXIMUM BENEFIT ................................... F-48 4.1 OFF-SITE EXPOSURE COST............................................................................... F-49 4.2 OFF-SITE ECONOMIC COST ............................................................................... F-50 4.3 ON-SITE EXPOSURE COST ................................................................................ F-50 4.4 ON-SITE ECONOMIC COST ................................................................................. F-52 4.5 TOTAL COST OF SEVERE ACCIDENT RISK / MAXIMUM BENEFIT ................... F-54 5.0 SAMA IDENTIFICATION ........................................................................................... F-55 5.1 PRA IMPORTANCE .............................................................................................. F-55 5.2 PLANT IPE ............................................................................................................ F-55 5.3 PLANT IPEEE ....................................................................................................... F-55 5.4 INDUSTRY SAMA CANDIDATES ......................................................................... F-55 5.5 PLANT STAFF INPUT TO SAMA CANDIDATES .................................................. F-55 5.6 LIST OF PHASE I SAMA CANDIDATES ............................................................... F-55 6.0 PHASE I ANALYSIS .................................................................................................. F-67 7.0 PHASE II SAMA ANALYSIS ...................................................................................... F-86 7.1 SAMA BENEFIT .................................................................................................... F-86 7.1.1 Severe Accident Risk with SAMA Implemented ............................................. F-86 7.1.2 Cost of Severe Accident Risk with SAMA Implemented ................................. F-87 7.1.3 SAMA Benefit Calculation .............................................................................. F-87 7.2 COST OF SAMA IMPLEMENTATION ................................................................... F-87 8.0 SENSITIVITY ANALYSES ......................................................................................... F-95 8.1 PLANT MODIFICATIONS ...................................................................................... F-95 8.2 UNCERTAINTY ..................................................................................................... F-95 8.3 PEER REVIEW FACTS/OBSERVATIONS ............................................................ F-95 8.4 EVACUATION SPEED .......................................................................................... F-95 8.5 REAL DISCOUNT RATE ....................................................................................... F-96 Callaway Plant Unit 1 Environmental Report for License Renewal F-3

Attachment F Severe Accident Mitigation Alternatives TABLE OF CONTENTS (CONTINUED)

Section Page 8.6 ANALYSIS PERIOD .............................................................................................. F-96

9.0 CONCLUSION

S ...................................................................................................... F-103

10.0 REFERENCES

........................................................................................................ F-103 11.0 ANNEX - PRA RUNS FOR SELECTED SAMA CASES .......................................... F-105 Callaway Plant Unit 1 Environmental Report for License Renewal F-4

Attachment F Severe Accident Mitigation Alternatives ACRONYMS USED IN ATTACHMENT F AC alternating current AEPS alternate emergency power system AFW auxiliary feedwater AMSAC ATWS mitigation system actuation circuitry ASD atmospheric steam dump ATWS anticipated transient without scram BE basic events BOP balance of plant BWR boiling water reactor CCW component cooling water CDF core damage frequency CIF containment isolation failure CPI consumer price index CRD control rod drive CST condensate storage tank DC direct current EC emergency coordinator ECCS emergency core cooling system EDG emergency diesel generator EOP emergency operating procedure EPRI electric power research institute ESFAS engineered safety features actuation system ESW essential service water F&O fact and observation FIVE fire induced vulnerability evaluation HEP human error probability HFE human failure event HPSI high pressure safety injection HRA human reliability analysis HVAC heating ventilation and air-conditioning system IA instrument air IE initiating event ILRT integrated leak rate test IPE individual plant examination IPEEE individual plant examination - external events ISLOCA interfacing system LOCA LERF large early release frequency LOCA loss-of-coolant accident Callaway Plant Unit 1 Environmental Report for License Renewal F-5

Attachment F Severe Accident Mitigation Alternatives ACRONYMS USED IN ATTACHMENT F (CONTINUED)

LOOP loss of off-site power LSELS load shedding and emergency load sequencing MAAP modular accident analysis program MACCS2 MELCOR accident consequences code system, version 2 MACR maximum averted cost-risk MCC motor control center MOV motor operated valve MSL mean sea level MWe megawatts electric MWth megawatts thermal NEI Nuclear Energy Institute MSIV main steam isolation valve MSPI mitigating systems performance index NCP normal charging pump NFPA National Fire Protection Association NRC U.S. Nuclear Regulatory Commission NSAFP non-safety auxiliary feedwater pump OECR off-site economic cost risk PAG protective action guidelines PDS plant damage state PRA probabilistic risk analysis PORV pressure operated relief valve PWR pressurized water reactor RCP reactor coolant pump RHR residual heat removal RPV reactor pressure vessel RRW risk reduction worth RWST refueling water storage tank SAMA severe accident mitigation alternative SAMG severe accident mitigation guidelines SBO station blackout SER safety evaluation report SGTR steam generator tube rupture SI safety injection SLC standby liquid control SMA seismic margins analysis SPDS safety parameter display system SRP standard review plan SRV safety relief valve Callaway Plant Unit 1 Environmental Report for License Renewal F-6

Attachment F Severe Accident Mitigation Alternatives ACRONYMS USED IN ATTACHMENT F (CONTINUED)

SSC structures, systems, and components SW service water TD turbine driven TDAFW turbine driven auxiliary feedwater UHS ultimate heat sink UPS uninterruptable power supply UL Underwriters Laboratories VDC volts direct current WOG Westinghouse owners group Callaway Plant Unit 1 Environmental Report for License Renewal F-7

Attachment F Severe Accident Mitigation Alternatives

1.0 INTRODUCTION

1.1 PURPOSE The purpose of the analysis is to identify Severe Accident Mitigation Alternatives (SAMA) candidates at the Callaway Plant that have the potential to reduce severe accident risk and to determine whether implementation of the individual SAMA candidate would be cost beneficial.

Nuclear Regulatory Commission (NRC) license renewal environmental regulations require SAMA evaluation.

1.2 REQUIREMENTS

• 10 CFR 51.53(c)(3)(ii)(L)

- The environmental report must contain a consideration of alternatives to mitigate severe accidents if the staff has not previously considered severe accident mitigation alternatives for the applicants plant in an environmental impact statement or related supplement or in an environment assessment...

• 10 CFR 51, Subpart A, Appendix B, Table B-1, Issue 76

- The probability weighted consequences of atmospheric releases, fallout onto open bodies of water, releases to ground water, and societal and economic impacts from severe accidents are small for all plants. However, alternatives to mitigate severe accidents must be considered for all plants that have not considered such alternatives.

2.0 METHOD The SAMA analysis approach applied in the Callaway assessment consists of the following steps.

• Determine Severe Accident Risk Level 1 and 2 Probabilistic Risk Assessment (PRA) Model The Callaway PRA model (Section 3.1 - 3.2) was used as input to the Callaway Level 3 PRA analysis (Section 3.4).

The PRA results include the risk from internal events, and tornado-induced loss of offsite power. Other external hazards including internal flooding and fires are not evaluated in the PRA. The risk contribution from these non-PRA, external hazards was evaluated in the Individual Plant Examination - External Events (IPEEE) [29] and is added to the risk from the internal events PRA for the SAMA evaluations.

Level 3 PRA Analysis The Level 1 and 2 PRA output and site-specific meteorology, demographic, land use, and emergency response data was used as input for the Callaway Level 3 PRA (Section 3). This combined model was used to estimate the severe accident risk i.e., off-site dose and economic impacts of a severe accident.

Callaway Plant Unit 1 Environmental Report for License Renewal F-8

Attachment F Severe Accident Mitigation Alternatives

• Determine Total Monetary Value of Severe Accident Risk / Maximum Benefit The NRC regulatory analysis techniques to estimate the total monetary value of the severe accident risk were used throughout this analysis. In this step these techniques were used to estimate the maximum benefit that a SAMA could achieve if it eliminated all risk i.e., the maximum benefit (Section 4).

• SAMA Identification In this step potential SAMA candidates (plant enhancements that reduce the likelihood of core damage and/or reduce releases from containment) were identified by Callaway Plant staff, from the PRA model, Individual Plant Examination (IPE) [28] and IPEEE recommendations, and industry documentation (Section 5). This process included consideration of the PRA importance analysis because it has been demonstrated by past SAMA analyses that SAMA candidates are not likely to prove cost-beneficial if they only mitigate the consequences of events that present a low risk to the plant.

• Preliminary Screening (Phase I SAMA Analysis)

Because many of the SAMA candidates identified in the previous step are from the industry, it was necessary to screen out SAMA candidates that were not applicable to the Callaway design, candidates that had already been implemented or whose benefits have been achieved at the plant using other means, and candidates whose roughly estimated cost exceeded the maximum benefit. Additionally, PRA insights (specifically, importance measures) were used directly to screen SAMA candidates that did not address significant contributors to risk in this phase (Section 6).

• Final Screening (Phase II SAMA Analysis)

In this step of the analysis the benefit of severe accident risk reduction was estimated for each of the remaining SAMA candidates and compared to an implementation cost estimate to determine net cost-benefit (Section 7). The benefit associated with each SAMA was determined by the reduction in severe accident risk from the baseline derived by modifying the plant model to represent the plant after implementing the candidate. In general, the modeling approach used was a bounding approach to first determine a bounding value of the benefit. If this benefit was determined to be smaller than the expected cost, no further modeling detail was necessary. If the benefit was found to be greater that the estimated cost, the modeling was refined to remove conservatism in the modeling and a less conservative benefit was determined for comparison with the estimated cost.

Similarly, the initial cost estimate used in this analysis was the input from the expert panel (plant staff familiar with design, construction, operation, training and maintenance) meeting. All costs associated with a SAMA were considered, including design, engineering, safety analysis, installation, and long-term maintenance, calibrations, training, etc. If the estimated cost was found to be close to the estimated benefit, then first the benefit evaluation was refined to remove conservatism and if the estimated cost and benefit were still close, then the cost estimate was refined to assure that both the benefit calculation and the cost estimate are sufficiently accurate to justify further decision making based upon the estimates.

Callaway Plant Unit 1 Environmental Report for License Renewal F-9

Attachment F Severe Accident Mitigation Alternatives

• Sensitivity Analysis The next step in the SAMA analysis process involved evaluation on the impact of changes in SAMA analysis assumptions and uncertainties on the cost-benefit analysis (Section 8).

• Identify Conclusions The final step involved summarizing the results and conclusions (Section 9).

3.0 SEVERE ACCIDENT RISK The Callaway PRA models describe the results of the first two levels of the Callaway PRA.

These levels are defined as follows: Level 1 determines core damage frequencies (CDFs) based on system analyses and human reliability assessments; Level 2 evaluates the impact of severe accident phenomena on radiological releases and quantifies the condition of the containment and the characteristics of the release of fission products to the environment. The Callaway models use PRA techniques to:

• Develop an understanding of severe accident behavior

• Understand the most likely severe accident consequences

• Gain a quantitative understanding of the overall probabilities of core damage and fission product releases

• Evaluate hardware and procedure changes to assess the overall probabilities of core damage and fission product releases.

The PRA was initiated in response to NRC Generic Letter 88-20 [1], which resulted in an IPE and IPEEE analysis. The current PRA model, Revision 4b, includes internal events and tornado induced loss of offsite power. Other events and initiators such as internal floods, fires, high winds, and seismic are evaluated in separate analyses and not directly combined with the internal events PRA model.

The PRA models used in this analysis to calculate severe accident risk are described in this section. The Level 1 PRA model (internal and external), the Level 2 PRA model, PRA model review history, and the Level 3 PRA model, are described in Sections 3.1, 3.2 and 3.4.

3.1 LEVEL 1 PRA MODEL 3.1.1 Internal Events 3.1.1.1 Description of Level 1 Internal Events PRA Model The original Callaway PRA was developed to satisfy NRC's Generic Letter 88-20 requirement that each licensee perform an IPE to search for plant-specific severe accident vulnerabilities.

Results of the Callaway PRA were submitted to the NRC, pursuant to this requirement, in September of 1992. The NRC Safety Evaluation Report (SER) on the Callaway IPE submittal was issued in May 1996. Since completion of the Callaway IPE (PRA), the model has been used to support numerous plant programs.

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Attachment F Severe Accident Mitigation Alternatives The Callaway internal events CDF is calculated to be 1.66E-05/year (Table 3-1) when ISLOCA is included in the evaluation (ISLOCA is not normally calculated as an event type in the Level 1 model). The Callaway PRA was used to generate a list of basic events sorted according to their risk reduction worth (RRW) values as related to CDF. The top events in this list are those events that would provide the greatest reduction in the Callaway CDF if the failure probability were set to zero. The events were reviewed down to the 1.005 level, which corresponds to about a 0.5 percent change in the CDF given 100 percent reliability of the event. Table 3-2 documents the disposition of each basic event in the Callaway PRA with RRW values of 1.005 or greater. Basic events that do not represent failures to structures, systems, or components (SSCs) were not included in the list.

Table 3-1. Contributions to Internal Events CDF Contribution to Internal Initiating Event Type CDF (/year)

Small LOCA 5.93E-06 Station Blackout 4.71E-06 SGTR 2.35E-06 RCP Seal LOCA 8.63E-07 Reactor Trip 7.88E-07 All Steam Line Breaks 3.35E-07 Intermediate LOCA 3.67E-07 Anticipated Transient without Scram (ATWS) 2.04E-07 ISLOCA 1.73E-07 Loss of Feedwater 1.65E-07 Very Small LOCA 1.29E-07 Loss of CCW 1.20E-07 Loss of SW 1.15E-07 Feedwater Line Break 9.01E-08 Loss of DC Vital Bus 6.93E-08 Loss of Offsite Power 4.65E-08 PORV Fails to Reclose 4.52E-08 Large LOCA 4.21E-08 Total 1.66E-05 LOCA = loss of coolant accident; SGTR = steam generator tube rupture; RCP = reactor coolant pump; CCW = component cooling water; SW = service water; DC = direct current; PORV = power operated relief valve Callaway Plant Unit 1 Environmental Report for License Renewal F-11

Attachment F Severe Accident Mitigation Alternatives Table 3-2. Level 1 Importance List Review Basic Event Name Basic Event Description RRW Associated SAMA IE-S2 SMALL LOCA INITIATING EVENT FREQUENCY 1.554 Safety Injection SAMAs IE-T1 LOSS OF OFFSITE POWER INITIATING EVENT 1.514 Loss of Offsite Power SAMAs FREQUENCY OP-XHE-FO-ECLRS2 OPERATOR FAILS TO ALIGN ECCS SYSTEMS FOR 1.389 SAMA 36, see note on COLD LEG RECIRC operator action events IE-TSG STEAM GENERATOR TUBE RUPTURE IE FREQUENCY 1.166 SGTR SAMAs OP-XHE-FO-SGTRDP OPERATOR FAILS TO C/D AND DEPRESS THERCS 1.082 see note on operator action AFTER SGTR events OP-XHE-FO- OPERATOR FAILS TO C/D AND DEPRESS RCSAFTER 1.082 see note on operator action SGTRWR WATER RELIEF events IE-T3 TURBINE TRIP WITH MAIN FEEDWATER AVAILABLE IE 1.07 Initiating Event FREQ BB-PRV-CC-V455A PRESSURIZER PORV PCV455A FAILS TO OPEN 1.053 PORV SAMAs BB-PRV-CC-V456A PRESSURIZER PORV PCV456A FAILS TO OPEN 1.053 PORV SAMAs NE-DGN-DR-NE01-2 DGNS CC FTR. 1.049 Loss of Offsite Power SAMAs AE-CKV-DF-V120-3 CHECK VALVES AEV120121,122,123 COMMON CAUSE 1.048 Feedwater SAMAs FAIL TO OPEN EF-PSF-TM-ESWTNB ESW TRAIN B IN TEST OR MAINTENANCE 1.045 Service Water SAMAs OP-XHE-FO-ACRECV OPERATOR FAILS TO RECOVER FROM A LOSSOF 1.044 SAMA 22 OFFSITE POWER EF-PSF-TM-ESWTNA ESW TRAIN A IN TEST OR MAINTENANCE 1.043 Service Water SAMAs FAILTORECOVER-8 PROBABILITY THAT POWER IS NOT RECOV-ERED IN 8 1.042 Loss of Offsite Power SAMAs HOURS.

EF-MDP-DR-EFPMPS ESW PUMPS CC FTR. 1.041 Service Water SAMAs OP-XHE-FO- OPERATOR FAILS TO INITIATE CCW FLOW TO THE 1.037 Cooling Water SAMAs CCWRHX RHR HXS FAILTORECOVER-12 CONDITIONAL PROB. THAT PWR IS NOT RE-COVERED 1.035 Loss of Offsite Power SAMAs IN 12 HRS.

EF-MDP-FR-PEF01A ESW PUMP A (PEF01A)FAILS TO RUN 1.033 Service Water SAMAs Callaway Plant Unit 1 Environmental Report for License Renewal F-12

Attachment F Severe Accident Mitigation Alternatives Table 3-2. Level 1 Importance List Review (Continued)

Basic Event Name Basic Event Description RRW Associated SAMA FB-XHE-FO-FANDB OPERATOR FAILS TO ESTABLISH RCS FEED AND 1.032 see note on operator action BLEED events OP-XHE-FO-ECLR OPERATOR FAILS TO ALIGN ECCS SYSTEMS FOR 1.031 see note on operator action COLD LEG RECIRC events TORNADO-T1-EVENT CONDITIONAL PROB. TORNADO T(1) EVENT LOSS OF 1.031 SAMA 15 AEPS EF-MDP-FR-PEF01B ESW PUMP B (PEF01B)FAILS TO RUN 1.025 Service Water SAMAs EG-MDP-DS- ALL 4 EG PUMPS CC FTS. 1.025 Cooling Water SAMAs EGPMP4 IE-S1 INTERMEDIATE LOCA INITIATING EVENT FREQUENCY 1.023 Safety Injection SAMAs IE-TMSO MAIN STEAMLINE BREAK OUTSIDE CTMT IE 1.022 Initiating Event FREQUENCY AL-TDP-TM-TDAFP TDAFP IN TEST OR MAINTENANCE 1.019 AFW Related SAMAs BB-RCA-WW-RCCAS TWO OR MORE RCCA'S FAIL TO INSERT (MECH. 1.019 ATWS SAMAs CAUSES)

EF-DRAIN-TRAINB ALL TRAIN B SW UNAVAIL. DUE TO DRAINAGE OF EF 1.019 SW SAMAs TRAIN B.

EG-HTX-TM- CCW TRAIN B TEST/MAINT. (E.G. HX B TEST/MAINT.) 1.016 CCW SAMAs CCWHXB VL-ACX-DS-GL10AB ROOM COOLER SGL10A, B CC FTS 1.014 HVAC SAMAs EF-MOV-CC-EFHV37 VALVE EFHV37 FAILS TO OPEN 1.013 Service Water SAMAs IE-S3 VERY SMALL LOCA INITIATING EVNET 1.013 Initiating Event NE-DGN-FR-NE0112 DIESEL GENERATOR NE01 FTR - 12 HR MT 1.013 Loss of Offsite Power SAMAs NE-DGN-FR-NE0212 DIESEL GENERATOR NE02 FTR - 12 HR MT 1.013 Loss of Offsite Power SAMAs NE-DGN-TM-NE01 DIESEL GENERATOR NE01 IN TEST OR MAINTENANCE 1.013 Loss of Offsite Power SAMAs NE-DGN-TM-NE02 DIESEL GENERATOR NE02 IN TEST OR MAINTENANCE 1.013 Loss of Offsite Power SAMAs IE-T2 LOSS OF MAIN FEEDWATER IE FREQUENCY 1.012 Initiating Event NE-DGN-FS-NE01 DIESEL GENERATOR NE01 FAILS TO START 1.012 Loss of Offsite Power SAMAs AL-TDP-FS-TDAFP TDAFP FAILS TO START 1.011 AFW Related SAMAs Callaway Plant Unit 1 Environmental Report for License Renewal F-13

Attachment F Severe Accident Mitigation Alternatives Table 3-2. Level 1 Importance List Review (Continued)

Basic Event Name Basic Event Description RRW Associated SAMA EF-MDP-FS-PEF01A ESW PUMP A (PEF01A)FAILS TO START 1.011 Service Water SAMAs EJ-PSF-TM-EJTRNB RHR TRAIN B IN TEST OR MAINTENANCE 1.011 Core Cooling SAMAs NE-DGN-FS-NE02 DIESEL GENERATOR NE02 FAILS TO START 1.011 Loss of Offsite Power SAMAs EF-MDP-DS-EFPMPS ESW PUMPS CC FTS 1.01 SW SAMAs EF-MOV-CC-EFHV38 VALVE EFHV38 FAILS TO OPEN 1.01 Service Water SAMAs OP-XHE-FO-AEPS1 OPERATOR FAILS TO ALIGN AEPS TO NB BUS IN 1 HR 1.01 Loss of Offsite Power SAMAs VD-FAN-FR-CGD02A UHS C.T. ELEC. ROOM SUPPLY FAN CGD02A FAILS TO 1.01 HVAC SAMAs RUN AE-CKV-DF-V124-7 CHECK VALVES AEV124,125,126,127 COMMON CAUSE 1.009 SAMA 163 FAIL TO OPEN AEPS-ALIGN-NB02 PDG ALIGN TO NB02 (FAIL TO ALIGN PDG TO NB01) 1.009 Loss of Offsite Power SAMAs EF-MDP-FS-PEF01B ESW PUMP B (PEF01B)FAILS TO START 1.009 Service Water SAMAs EF-MOV-D2-V37-38 VALVES EFHV37 & 38 COMMON CAUSE FAIL TO 1.009 Service Water SAMAs CLOSE (2 VALVES)

FAILTOMNLINSRODS OPERATOR FAILS TO MANUALLY DRIVE RODS INTO 1.009 see note on operator action CORE events OP-COG-FRH1 OPERATORS FAIL TO DIAGNOSE RED PATH ON HEAT 1.009 see note on operator action SINK events VD-FAN-FR-CGD02B UHS C.T. ELEC. ROOM SUPPLY FAN CGD02B FAILS TO 1.009 HVAC SAMAs RUN AEPS-ALIGN-NB01 PDG ALIGN TO NB01 (FAIL TO ALIGN PDG TO NB02) 1.008 Loss of Offsite Power SAMAs AL-XHE-FO-SBOSGL OPERATOR FAILS TO CONTROL S//G LEVEN AFTER 1.008 see note on operator action COMPLEX EVENT events EF-MOV-OO-EFHV59 VALVE EFHV59 FAILS TO CLOSE 1.008 Service Water SAMAs EJ-PSF-TM-EJTRNA RHR TRAIN A IN TEST OR MAINTENANCE 1.008 Core Cooling SAMAs FAILTOREC-EFHV59 OPERATORS FAIL TO RECOVER (CLOSE) EFHV59 1.008 see note on operator action events VL-ACX-FS-SGL10A ROOM COOLER FAN SGL10A FAILS TO START 1.008 HVAC SAMAs AL-PSF-TM-ALTRNB AFW TRAIN B IN TEST OR MAINTENANCE 1.007 AFW Related SAMAs Callaway Plant Unit 1 Environmental Report for License Renewal F-14

Attachment F Severe Accident Mitigation Alternatives Table 3-2. Level 1 Importance List Review (Continued)

Basic Event Name Basic Event Description RRW Associated SAMA BN-TNK-FC-RWSTUA RWST UNAVAILALBE 1.007 SAMA 171 EG-MDP-DR- ALL 4 EG PUMPS CC FTR. 1.007 CCW SAMAs EGPMP4 EJ-XHE-FO-PEJ01 OPERATOR FAILS TO START AN RHR PUMP FOR 1.007 see note on operator action LONG TERM C/D events IE-TC LOSS OF ALL COMPONENT COOLING WATER IE 1.007 CCW SAMAs FREQUENCY IE-TSW LOSS OF SERVICE WATER INITIATING EVENT 1.007 SW SAMAs SA-ICC-AF-RWSTL1 NO RWST LOW LEVEL SIGNAL AVAILABLE (SEP GRP 1) 1.007 Core Cooling SAMAs AE-XHE-FO-MFWFLO FAILURE TO RE-ESTABLISH MFW FLOW DUE TO 1.006 see note on operator action HUMAN ERRORS events BG-MDP-FR-NCP MOTOR DRIVEN CHARGING PUMP FAILS TO RUN 1.006 ECCS SAMAs EJ-MDP-DS-EJPMPS RHR PUMPS CC FAIL TO START 1.006 Core Cooling SAMAs EJ-MOV-CC-V8811A VALVE EJHV8811A FAILS TO OPEN 1.006 Core Cooling SAMAs IE-TFLB FEEDLINE BREAK DOWNSTREAM OF CKVS IE 1.006 Feedwater SAMAs FREQUENCY NF-ICC-AF-LSELSA LOAD SHEDDER TRAIN A FAILS TO SHED LOADS 1.006 Loss of Offsite Power SAMAs OP-XHE-FO-SGISO OPERATOR FAILS TO ISOLATE THE FAULTED S/G 1.006 see note on operator action FOLLOWING SGTR events SA-ICC-AF-MSLIS NO SLIS ACTUATION SIGNAL 1.006 ATWS SAMAs SA-ICC-AF-RWSTL4 NO RWST LOW LEVEL SIGNAL AVAILABLE (SEP GRP 1.006 Core Cooling SAMAs 4)

VL-ACX-FS-SGL10B ROOM COOLER FAN SGL10B FAILS TO START 1.006 HVAC SAMAs VM-BDD-CC-GMD001 DAMPER GMD001 FAILS TO OPEN 1.006 HVAC SAMAs VM-BDD-CC-GMD004 DAMPER GMD004 FAILS TO OPEN 1.006 HVAC SAMAs VM-EHD-CC-GMTZ1A ELEC/HYDR OP DAMPER GMTZ01A FAILS TO OPEN 1.006 HVAC SAMAs AL-MDP-FR-MDAFPB MDAFPB FAILS TO RUN AFTER START 1.005 AFW Related SAMAs AL-TDP-FR-TDAFP TDAFP FAILS TO RUN AFTER START 1.005 AFW Related SAMAs Callaway Plant Unit 1 Environmental Report for License Renewal F-15

Attachment F Severe Accident Mitigation Alternatives Table 3-2. Level 1 Importance List Review (Continued)

Basic Event Name Basic Event Description RRW Associated SAMA BM-AOV-OO-BMHV1 BLOWDOWN ISOLATION VALVE BMHV0001 FAILS TO 1.005 AFW Related SAMAs CLOSE BM-AOV-OO-BMHV4 BLOWDOWN ISOLATION VALVE BMHV0004 FAILS TO 1.005 AFW Related SAMAs CLOSE EJ-MOV-CC-V8811B VALVE EJHV8811B FAILS TO OPEN 1.005 Core Cooling SAMAs EJ-MOV-D2-8811AB VALVES EJHV8811A & B COMMON CAUSE FAIL TO 1.005 Core Cooling SAMAs OPEN NE-DGN-FR-NE01-2 DGN NE01 FAILS TO RUN (1 HR MISSION TIME) 1.005 Loss of Offsite Power SAMAs NF-ICC-AF-LSELSB LOAD SHEDDER TRAIN B FAILS TO SHED LOADS 1.005 Loss of Offsite Power SAMAs VM-BDD-CC-GMD006 DAMPER GMD006 FAILS TO OPEN 1.005 HVAC SAMAs VM-BDD-CC-GMD009 DAMPER GMD009 FAILS TO OPEN 1.005 HVAC SAMAs VM-EHD-CC-GMTZ11 ELEC/HYDR OP DAMPER GMTZ11A FAILS TO OPEN 1.005 HVAC SAMAs RCS = reactor coolant system; IE = initiating event; CC = common cause; FTR = fail to run; ESW = essential service water; ECCS =

emergency core cooling system; FTS = fail to start Note 1 - The current plant procedures and training meet current industry standards. There are no additional specific procedure improvements that could be identified that would affect the result of the human error probability (HEP) calculations. Therefore, no SAMA items were added to the plant specific list of SAMAs as a result of the human actions on the list of basic events with RRW greater than 1.005.

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Attachment F Severe Accident Mitigation Alternatives 3.1.1.2 Level 1 PSA Model Changes Since IPE Submittal The Callaway Level 1 internal events PRA model was developed in response to USNRC Generic Letter 88-20 [1]. The results of the internal events PRA model, developed for the IPE, were submitted to the NRC via letter ULNRC-2703, dated September 29, 1992. Following development and submittal of the results of the initial Callaway internal events PRA model, the model was revised a number of times, to maintain fidelity with the as-built, as-operated plant, to improve modeling methods, etc. Table 3-3, below, delineates the various internal events PRA model updates, the CDF resulting from each, and a high-level summary of the changes made to the internal events model. Additional detail on the various PRA model updates is provided later in this section.

Table 3-3. Callaway Internal Events PRA Update History Selected Changes from Previous Internal Events

-1 PRA Update Completion Date Update CDF (yr )

IPE 9/92 NA 5.85E-5 First Update 2/99

• Updated internal flooding analysis. 3.96E-5

• Incorporated the Normal Charging Pump.

• Incorporated the swing battery chargers.

Second Update 10/00

• Revised EDG mission times. 3.09E-5

• Incorporated self-assessment findings. (Self-assessment conducted in preparation for owners group peer review.)

Third Update 5/04

• Updated internal flooding analysis. 4.43E-5

• Expanded common cause failure modeling.

• Incorporated plant-specific LOOP frequency.

• Credited recovery of only offsite power following station blackout.

Fourth Update 4/06

• Updated HRA for risk-significant 5.18E-5 HFEs.

• Implemented very low quantification cutset truncation value to comply with MSPI requirements.

Update 4A 11/10

• Incorporated Non-Safety Aux. 2.64E-5 Feedwater Pump.

• Incorporated temporary diesel-generator modification.

Update 4B 4/11

• Incorporated the Alternate Emergency 2.61E-5 Power System modification.

LOOP = loss of offsite power; HRA = human reliability analysis; HFE = human failure event; MSPI = mitigating system performance index The various internal events PRA updates, delineated above, are described in more detail, below.

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Attachment F Severe Accident Mitigation Alternatives First PRA Update The first update of the Callaway internal events PRA was completed in February 1999. The primary purpose of this revision to the internal events PRA was to factor plant physical and data changes into the PRA model, such that fidelity between the PRA model and the as-built, as operated plant was maintained. Following are noteworthy changes made to the PRA model.

• The internal flooding analysis was revised.

• Valves BGHV8357A and B, involved in the RCP seal injection function, were changed from solenoid-operated valves to motor-operated valves.

• In the RCP seal injection function, the positive displacement charging pump (PDP) was replaced with a centrifugal charging pump, i.e., the Normal Charging Pump (NCP). The NCP is not dependent on separate cooling systems. The NCP provided for additional mitigation capability following a loss of all service water or loss of all component cooling water initiating event.

• The possibility that the standby train of ESW is drained for maintenance was added to the model. In this configuration, the affected ESW heat loads cannot be cooled by non-safety service water.

• A recovery event was added for valve EFHV59.

• Logic for re-start of CCW pump train A was added to the model.

• A recovery event was added for valve EFHV52.

• A test/maintenance event was added to the model for the safety injection accumulators.

• Start logic for the emergency diesel-generator fuel oil transfer pumps was changed in the model to reflect a plant modification.

• System modeling was added to reflect a plant modification that added a swing battery charger to each train of 125 VDC power.

• System modeling was changed to require two (2) atmospheric steam dumps (ASDs), for cooldown and depressurization, as opposed to one (1) ASD.

• Certain initiating event frequencies were updated.

• Test/maintenance unavailabilities were updated.

The CDF generated via quantification of the First PRA Update was 3.96E-5 per year. The impact of the individual changes made to the PRA, above, was not determined.

Second PRA Update The Second PRA Update was completed in October 2000. The purpose of this update was to address findings stemming from a self-assessment, which was conducted prior to a Westinghouse Owners Group (WOG) PRA peer review. Following are noteworthy changes made to the internal events PRA in the Second PRA Update.

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Attachment F Severe Accident Mitigation Alternatives

• Non-safety service water system models were revised to incorporate pump runout scenarios.

• LOCA initiating event frequencies were updated.

• A correction was made to the high-head ECCS system model used to quantify station blackout with power recovery.

• Emergency diesel-generator mission times were refined.

• All event tree transfer sequences were accounted for in this update. (Previously, some transfer sequences were excluded, based on their low frequencies.)

The CDF generated via quantification of the Second PRA Update was 3.09E-5 per year. The impact of the individual changes made to the PRA, above, was not determined.

Third PRA Update The Third PRA Update was completed in May 2004. The primary purposes of this update were to maintain fidelity between the plant and PRA model, and to address a number of findings from the WOG PRA peer review. Following are noteworthy changes made to the internal events PRA in the Third PRA Update.

• The internal flooding analysis was revised.

• The feedwater isolation valve actuators were changed to system process medium actuators.

• A common cause check valve failure was added to the main feedwater fault tree.

• The system model representing failure of a pressurizer power-operated relief or safety valve to reclose following a transient was enhanced.

• The loss of all service water initiating event frequency model was revised.

• Automatic strainers were added to the normal service water system models.

• Common cause failure of the essential service water strainers was added to the system models.

• The loss of component cooling water initiating event frequency model was revised.

• Common cause modeling was expanded for rotating components.

• LOOP and other initiator frequencies were updated.

• Recovery of only offsite power was credited following a station blackout.

• Component failure rate data was updated.

• Test/maintenance unavailability data was updated.

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Attachment F Severe Accident Mitigation Alternatives The CDF generated via quantification of the Third PRA Update was 4.43E-5 per year. The impact of the individual changes made to the PRA, above, was not determined.

Fourth PRA Update The Fourth PRA update was completed in April 2006. The purposes of the Fourth Update were to maintain fidelity with the plant, address additional findings from the WOG peer review and implement model enhancements in support of the MSPI. Following are noteworthy changes made to the internal events PRA in the Fourth PRA Update.

• Revised the main steam and feedwater isolation fault tree models.

• Implemented a revised HRA for risk-significant HFEs.

• Implemented very low quantification cutset truncation values to comply with MSPI requirements.

The CDF generated via quantification of the Fourth PRA Update was 5.18E-5 per year. The impact of the individual changes made to the PRA, above, was not determined.

PRA Update 4A This PRA update was completed in November 2010. The primary motivation for this PRA update was to credit plant modifications implemented to enhance nuclear safety. Following are noteworthy changes made to the internal events PRA in Update 4A.

• Incorporated the Non-Safety Aux. Feedpump (NSAFP).

• Updated common cause failure data.

• Converted initiating event frequency values to a per reactor-year basis.

• Incorporated a temporary EDG modification.

The CDF generated via quantification of PRA Update 4A was 2.64E-5 per year. The impact of the individual changes made to the PRA, above, was not determined.

PRA Update 4B This PRA update was completed in April 2011. The primary motivation for this PRA update was to credit the Alternate Emergency Power System (AEPS) modification. Following are noteworthy changes made to the internal events PRA in Update 4B.

• Incorporated the AEPS modification.

• The Auxiliary Feedwater fault tree was revised based on balance of plant (BOP) emergency safety features actuation system (ESFAS) attributes.

The CDF generated via quantification of PRA Update 4B was 2.61E-5 per year. The impact of the individual changes made to the PRA, above, was not determined.

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Attachment F Severe Accident Mitigation Alternatives 3.1.2 External Events 3.1.2.1 Internal Fires Risk Analysis For the IPEEE, Callaway used the EPRI FIVE methodology. The assumptions and screening criteria used in implementing the FIVE methodology for Callaway are discussed in the IPEEE submittal. The Callaway FIVE analysis has not been updated since the IPEEE. A fire PRA is under development to support transition of the Callaway fire protection program to NFPA 805 requirements; however, this fire model was not available for performance of the SAMA analysis.

The preliminary results of the NFPA 805 fire PRA modeling show a CDF of 2.00E-5/yr. which was used in this analysis. This fire CDF is consistent with previous analysis results.

3.1.2.2 Seismic Events Risk Analysis For the IPEEE, Callaway used the EPRI seismic margins analysis (SMA) method. This analysis was transmitted to NRC in the IPEEE submittal. The latest estimate of the Callaway seismic contribution to CDF is 5.00E-6/yr. A 2010 NRC risk assessment relating to Generic Issue 199 estimated Callaway seismic core damage frequency at approximately 2E-6/yr using 2008 USGS seismic hazard curves and a weakest link model. Comparing this to the frequency employed in the SAMA analysis, it appears that Callaways 5E-6/yr seismic contribution to CDF is conservative relative to the NRC assessment under Generic Issue 199.

3.1.2.3 Other External Events Risk Analysis To address potential vulnerabilities from the effects of high winds, floods, and transportation and nearby facility accidents for the IPEEE, Callaway reviewed plant-specific hazard data and its licensing basis. Callaway also determined that there were no significant changes, relative to these sources of risk, since the Operating License was issued. The only risk impact from high winds is from tornado events. This risk is estimated to be 2.50E-5/yr. Conformance to the 1975 Standard Review Plan (SRP) was also assessed. Callaways assessment of these sources of external events risk has not been updated since the IPEEE.

The Callaway internal events PRA model does not include an analysis of internal flooding. The risk due to internal floods was analyzed in the Callaway IPE, but not included in the internal events PRA model. The IPE determined the contribution to CDF from internal flooding to be 9.14E-6/yr.

The Callaway IPEEE concluded that external flooding does not present a risk to the Callaway Plant. The Probable Maximum Flood for the Missouri River in the vicinity of the Callaway Plant is estimated to be 548 feet above mean sea level (msl). The Callaway Plant grade level is 840 feet above msl and is not impacted by river flooding on the Missouri River. Flooding due to intense local rainfall is estimated to result in local ponding to elevation 839.87 feet above msl.

This is 0.13 feet below plant grade and 0.63 feet below the safety-related facilities standard plant elevation.

3.1.2.4 Treatment of External Events in the SAMA Analysis The contributions of the external events initiators are summarized in Table 3-4:

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Attachment F Severe Accident Mitigation Alternatives Table 3-4. IPEEE CONTRIBUTOR

SUMMARY

EXTERNAL EVENT INITIATOR GROUP CDF Contributor CDF High Winds 2.50E-05/yr.

Internal Flooding 9.14E-06/yr.

Fire 2.00E-05/yr.

Seismic 5.00E-06/yr.

External CDF 5.91E-05/yr.

The method chosen to account for external events contributions in the SAMA analysis is to use a multiplier on the internal events results. This is simply the ratio of total CDF (including internal and external) to only internal CDF. This ratio is called the External Events multiplier and its value is calculated as follows:

EE Multiplier = (1.66E-05+5.91E-05) / (1.66E-05) = 4.57 3.2 LEVEL 2 PSA MODEL CHANGES SINCE IPE SUBMITTAL The full Level 2 analysis, performed for the IPE and addressed in the IPE submittal, was used, in 2000, for development of a large early release frequency (LERF) model. The driver for this effort was that LERF was the only Level 2-related metric used in most risk-informed applications. In 2002, the LERF model was updated to reflect the internal events PRA Second Update.

The Level 2 PRA model was updated in 2011. As part of the update, the model:

• includes containment bypass events, containment isolation failures, early containment failure modes, induced steam generator tube ruptures, and late containment failure modes

• applies plant damage state definitions to the Level 1 accident sequences consistent with the updated Level 2 analysis structure and incorporates a realistic, plant-specific analysis of significant containment challenges

• addresses dependencies between Level 1 and Level 2 basic events

• models the probability of RCS hot leg or surge line failure during high-pressure core damage scenarios

• determines the sequences that contribute to LERF based on source term calculations using MAAP 4.0.7

• considers whether additional credit for scrubbing of fission products may affect the significant contributors to LERF

• groups accident progression sequences into release categories based on the containment event tree end states and calculates the frequency of each release category and the release characteristics (timing and magnitude) for each release category Callaway Plant Unit 1 Environmental Report for License Renewal F-22

Attachment F Severe Accident Mitigation Alternatives

• Performs the LERF quantification based on requirement LE-E4 of the ASME PRA Standard.

• performs LERF calculations including uncertainty and sensitivity studies as appropriate

• reviews significant large early release accident progression sequences for reasonableness and determines if credit for repair, operation in adverse environments, or operation after containment failure may reduce LERF.

Large early release frequencies, generated with the initial and updated LERF models, are provided in Table 3-5.

Table 3-5. LERF Models and Frequencies

-1 LERF Model Completion Date LERF (yr )

Initial LERF Model (used First Update Level 1 10/2000 4.22E-7 model (2/99))

Updated LERF Model (uses Second Update 6/2002 4.20E-7 Level 1 model (10/00))

Updated full Level 2 Model (used 4B Level 1 4/2011 2.73E-6 model)

There were no changes to major modeling assumptions, containment event tree structure, accident progression, source term calculations or other Level 2 attributes, used in the IPE Level 2 analysis, when developing the initial and updated models.

3.2.1. Level 1 to Level 2 Interface Plant damage states and their representative Level 1 accident scenarios provide an interface between the Level 1 and Level 2 analyses. Each Level 1 accident sequence that leads to core damage consists of a unique combination of an initiating event followed by the success or failure of various plant systems (including operator actions). Due to the large number of accident sequences created by the Level 1 PRA, the Level 1 sequences that result in core damage can be grouped into plant damage state (or accident class) bins. Each bin collects all of those sequences for which the progression of core damage, the release of fission products from the fuel, the status of the containment and its safeguards systems, and the potential for mitigating the potential radiological source terms are similar. The detailed containment event tree then analyzes each plant damage state bin as a group.

Plant damage state bins can be used as the entry states to the containment event tree quantification (similar to initiating events for the Level 1 PRA), or can be used to direct sequences onto specific containment event tree branches. The plant damage state (PDS) bins are characterized by the status of containment bypass due to SGTR or ISLOCA, the status of offsite/emergency power, reactor coolant system pressure, and the status of water in the reactor cavity.

The definition of plant damage states incorporates information from the outcome of the Level 1 analysis that is important to the determination of containment response and the release of radioactive materials into the environment.

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Attachment F Severe Accident Mitigation Alternatives The modeling approach for the current revision of the Level 2 PRA uses the WinNUPRA software package, which allows the incorporation of complete Level 1 results information (i.e.,

cutsets) into the Level 2 PRA model. This permits the somewhat artificial boundary between the Level 1 event trees and the containment event tree that exists in some Level 2 analyses to be eliminated from this analysis. Safety functions that may have been modeled in separate bridge trees can also be directly incorporated into the WinNUPRA model. That is, active systems such as containment coolers and containment spray are modeled in the Level 2 analysis alongside the Level 2 phenomenological events in order to accurately capture system dependencies such as actuation signals, electrical power, and cooling water.

Along with containment systems performance, the containment event trees (CETs) consider the influence that physical and chemical processes have on the integrity of the containment and on the release of fission products once core damage has occurred. The important physical conditions in the RCS and the containment include the pressure inside the reactor vessel at the onset of core damage, whether the reactor cavity is flooded, and the availability of cooling on the secondary side of the steam generators.

In this study, the RCS pressure identified in the definition of PDSs is that which occurs at the onset of core damage. Events that could influence the change in pressure after the onset of core damage but prior to vessel breach are addressed in the CETs. The two most important effects of high pressure for a Level 2 PRA are challenges to the steam generator tubes and direct containment heating. Because of this, three RCS pressure level categories are considered in the PRA: high, medium, or low. Pressure level assignment was based on the accident initiators (e.g., medium and large LOCAs result in low pressure) and the availability of feedwater (which results in pressure low enough to alleviate steam generator tube challenges, but has slightly different effects on accident progression - categorized as medium pressure). In general, either a medium/large LOCA, depressurization through the PORVs, or hot leg creep rupture is required to reach low pressure. Smaller LOCAs and transients with steam generators being fed are considered to be at medium pressure at the time of core damage. Without secondary side cooling, smaller LOCAs and transients are modeled as high pressure scenarios.

The presence of water in the reactor cavity is important to containment response because the interaction of this water with hot core debris can affect the immediate containment response at the time of vessel breach and the long-term cooling of core debris. Water in the reactor cavity at the time of vessel breach is an important issue for containment response due to its effect on hydrogen generation, the possibility of steam explosion, and quenching of debris.

Because of the way individual sequences are processed through WinNUPRA using unique house event files, sequences with a loss of offsite power or a station blackout must be identified in order to carry those house event settings through the Level 2 analysis. Identification of power status as a plant damage state parameter ensures that dependencies between the Level 1 and Level 2 analyses are properly captured.

Initiating events that bypass containment are treated separately in the Level 2 CET. As mentioned in the discussion of top events, containment bypass is identified by ISLOCA and SGTR events.

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Attachment F Severe Accident Mitigation Alternatives 3.2.2 Plant Damage State Classifications

• Containment Bypass

- B: Bypass BI: Bypass due to ISLOCA BT: Bypass due to tube rupture

• Status of Electric Power

- O: Loss of Offsite Power

- S: Station Blackout

• RCS Pressure

- H: High Pressure (sequences without RCS leakage or SG cooling)

- M: Medium Pressure (sequences without RCS leakage, but with SG cooling)

- L: Low Pressure (sequences that depressurize due to significant RCS leakage)

• Reactor Cavity

- W: Wet cavity (due to injection of RWST during Level 1)

- D: Dry cavity The PDS is therefore a two or three character code that defines the important sequence characteristics for the Level 2 analysis. The assignment of each individual Level 1 sequence is documented in Appendix B. In addition to the general PDS assignment, each PDS is supplemented with additional characters to differentiate the house event file to be used during quantification. This results in a total PDS code up to five characters in length. For example, sequence number 2 from the TAT1 Level 1 event tree, TAT1S02 is assigned to plant damage state OHDTA: O for Loss of Offsite Power, H for high pressure, D for dry reactor cavity, and TA for house settings file HSE-T1.

The Callaway PRA was used to generate a list of basic events sorted according to their RRW values as related to LERF and Large Late Release. The top events in this list are those events that would provide the greatest reduction in the Callaway LERF and Large Late Release if the failure probability were set to zero. The events were reviewed down to the 1.005 level, which corresponds to about a 0.5 percent change in the LERF/Large Late Release given 100 percent reliability of the event. Table 3-6 documents the disposition of each basic event in the Callaway PRA with RRW values of 1.005 or greater as related to LERF. Table 3-7 documents the disposition of each basic event in the Callaway PRA with RRW values of 1.005 or greater as related to Late releases. Basic events that do not represent SSC failures were not included in the list.

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Attachment F Severe Accident Mitigation Alternatives Table 3-6. LERF Importance Review Basic Event Name Basic Event Description RRW Associated SAMA IE-TSG STEAM GENERATOR TUBE RUPTURE IE FREQUENCY 6.808 SGTR SAMAs OP-XHE-FO-SGTRDP OPERATOR FAILS TO C/D AND DEPRESS THERCS AFTER SGTR 1.835 See note on operator action events OP-XHE-FO-SGTRWR OPERATOR FAILS TO C/D AND DEPRESS RCSAFTER WATER 1.835 See note on operator action RELIEF events BB-PRV-CC-V455A PRESSURIZER PORV PCV455A FAILS TO OPEN 1.314 SAMA 161 BB-PRV-CC-V456A PRESSURIZER PORV PCV456A FAILS TO OPEN 1.314 SAMA 161 BI ISLOCA CDF 1.068 ISLOCA SAMAs OP-XHE-FO-SGISO OPERATOR FAILS TO ISOLATE THE FAULTEDS/G FOLLOWING 1.037 See note on operator action SGTR events IE-T1 LOSS OF OFFSITE POWER INITIATING EVENT FREQUENCY 1.034 Loss of Offsite Power SAMAs IE-T3 TURBINE TRIP WITH MAIN FEEDWATER AVAILABLE IE FREQ 1.028 Initiating Event AB-ARV-DF-SGPRVS S/G PORVS ABPV01, 02, 03, & 04 COMMONCAUSE FAIL TO OPEN 1.024 SAMA 89 AB-ARV-TM-ABPV03 S/G PORV ABPV0003 ISOLATED FOR TEST/MAINTENANCE 1.024 SAMA 89 FB-XHE-FO-FANDB OPERATOR FAILS TO ESTABLISH RCS FEED AND BLEED 1.023 SAMA 36, see note on operator action events AE-CKV-DF-V120-3 CHECK VALVES AEV120121,122,123 COMMON CAUSE FAIL TO 1.022 SAMA 163 OPEN AB-ARV-TM-ABPV01 S/G PORV ABPV0001 ISOLATED FOR TEST/MAINTENANCE 1.02 SAMA 89 BB-RCA-WW-RCCAS TWO (2) OR MORE RCCA's FAIL TO IN- SERT (MECH. CAUSES) 1.02 ATWS SAMAs SA-ICC-AF-MSLIS NO SLIS ACTUATION SIGNAL 1.016 Containment Isolation SAMAs AB-ARV-TM-ABPV04 S/G PORV ABPV0004 ISOLATED FOR TEST/MAINTENANCE 1.015 SAMA 89 AB-PHV-OO-ABHV17 MSIV "B" (AB-HV-17) FAILS TO CLOSE ON DEMAND 1.015 SAMA 89 TORNADO-T1-EVENT CONDITIONAL PROB. TORNADO T(1) EVENT LOSS OF AEPS 1.014 SAMA 15 BB-RLY-FT-72455 72 RELAY FAILS TO TRANSFER 1.011 SAMA 79 BB-RLY-FT-72456 72 RELAY FAILS TO TRANSFER 1.011 SAMA 79 BB-RLY-FT-AR455 AUX. RELAY FAILS TO TRANSFER 1.011 SAMA 79 BB-RLY-FT-AR456 AUX. RELAY FAILS TO TRANSFER 1.011 SAMA 79 Callaway Plant Unit 1 Environmental Report for License Renewal F-26

Attachment F Severe Accident Mitigation Alternatives Table 3-6. LERF Importance Review Basic Event Name Basic Event Description RRW Associated SAMA NE-DGN-DR-NE01-2 DGNS CC FTR. 1.01 Loss of Offsite Power SAMAs AB-ARV-CC-ABPV04 S/G PORV ASPV0004 FAILS TO OPEN 1.009 SAMA 89 VL-ACX-DS-GL10AB ROOM COOLER SGL10A, B CC FTS 1.009 HVAC SAMAs AB-ARV-CC-ABPV01 S/G PORV ASPV0001 FAILS TO OPEN 1.008 SAMA 89 AE-XHE-FO-MFWFLO FAILURE TO RE-ESTABLISH MFW FLOW DUE TO HUMAN 1.008 See note on operator action ERRORS events AL-TDP-TM-TDAFP TDAFP IN TEST OR MAINTENANCE 1.008 AFW SAMAs IE-TMSO MAIN STEAMLINE BREAK OUTSIDE CTMT IE FREQUENCY 1.008 AB-ARV-CC-ABPV03 S/G PORV ASPV0003 FAILS TO OPEN 1.007 SAMA 89 NE-DGN-FR-NE0112 DIESEL GENERATOR NE01 FTR - 12 HR MT 1.007 Loss of Offsite Power SAMAs NE-DGN-FR-NE0212 DIESEL GENERATOR NE02 FTR - 12 HR MT 1.007 Loss of Offsite Power SAMAs EJ-PSF-TM-EJTRNB RHR TRAIN B IN TEST OR MAINTENANCE 1.006 Core Cooling SAMAs OP-XHE-FO-ECA32 OPERATOR FAILS TO PERFORM C/D TO COLD S/D IAW ECA 3.2 1.006 See note on operator action events AB-AOV-CC-ABUV34 STEAM DUMP ABUV0034 FAILS TO OPEN 1.005 SAMA 89 AB-AOV-CC-ABUV35 STEAM DUMP ABUV0035 FAILS TO OPEN 1.005 SAMA 89 AB-AOV-CC-ABUV36 STEAM DUMP ABUV0036 FAILS TO OPEN 1.005 SAMA 89 AL-XHE-FO-SBOSGL OPERATOR FAILS TO CONTROL S//G LEVEN AFTER COMPLEX 1.005 See note on operator action EVENT events EJ-XHE-FO-PEJ01 OPERATOR FAILS TO START AN RHR PUMP FOR LONG TERM 1.005 See note on operator action C/D events FAILTOMNLINSRODS OPERATOR FAILS TO MANUALLY DRIVE RODS INTO CORE 1.005 ATWS SAMAs ISLOCA = interfacing system LOCA; S/G = steam generator Note 1 - The current plant procedures and training meet current industry standards. There are no additional specific procedure improvements that could be identified that would affect the result of the HEP calculations. Therefore, no SAMA items were added to the plant specific list of SAMAs as a result of the human actions on the list of basic events with RRW greater than 1.005.

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Attachment F Severe Accident Mitigation Alternatives Table 3-7. Late Release Importance Review Basic Event Name Basic Event Description RRW Associated SAMA IE-T1 LOSS OF OFFSITE POWER INITIATING EVENT FREQUENCY 4.51 Loss of Offsite Power SAMAs RECSWT1 RECOVERY POWER AND SW IN 8 HRS BEFORE CORE 1.474 Loss of Offsite Power SAMAs UNCVRED OP-XHE-FO-ACRECV OPERATOR FAILS TO RECOVER FROM A LOSSOF OFFSITE 1.14 SAMA 22, see note on POWER operator action events EF-PSF-TM-ESWTNB ESW TRAIN B IN TEST OR MAINTENANCE 1.136 Cooling Water SAMAs NE-DGN-DR-NE01-2 DGNS CC FTR. 1.133 Loss of Offsite Power SAMAs EF-MDP-DR-EFPMPS ESW PUMPS CC FTR. 1.129 Cooling Water SAMAs EF-PSF-TM-ESWTNA ESW TRAIN A IN TEST OR MAINTENANCE 1.127 Cooling Water SAMAs FAILTORECOVER-8 PROBABILITY THAT POWER IS NOT RECOV-ERED IN 8 HOURS. 1.105 Loss of Offsite Power SAMAs FAILTORECOVER-12 CONDITIONAL PROB. THAT PWR IS NOT RE-COVERED IN 12 1.098 Loss of Offsite Power SAMAs HRS.

IE-T3 TURBINE TRIP WITH MAIN FEEDWATER AVAILABLE IE FREQ 1.088 Initiating Event EF-MDP-FR-PEF01A ESW PUMP A (PEF01A)FAILS TO RUN 1.085 Cooling Water SAMAs FB-XHE-FO-FANDB OPERATOR FAILS TO ESTABLISH RCS FEED AND BLEED 1.076 SAMA 36, see note on operator action events EF-MDP-FR-PEF01B ESW PUMP B (PEF01B) FAILS TO RUN 1.074 Cooling Water SAMAs TORNADO-T1-EVENT CONDITIONAL PROB. TORNADO T(1) EVENT LOSS OF TEMP 1.073 Loss of Offsite Power SAMAs EDGS IE-S2 SMALL LOCA INITIATING EVENT FREQUENCY 1.067 Safety Injection SAMAs AE-CKV-DF-V120-3 CHECK VALVES AEV120121,122,123 COMMON CAUSE FAIL TO 1.05 SAMA 163 OPEN BB-RCA-WW-RCCAS TWO (2) OR MORE RCCA's FAIL TO IN- SERT (MECH. CAUSES) 1.048 ATWS SAMAs OP-XHE-FO-ECLRS2 OPERATOR FAILS TO ALIGN ECCS SYSTEMS FOR COLD LEG 1.042 SAMA 36, see note on RECIRC operator action events EF-DRAIN-TRAINB ALL TRAIN B SW UN- AVAIL. DUE TO DRAINAGE OF EF TRAIN B. 1.036 Cooling Water SAMAs NE-DGN-TM-NE02 DIESEL GEN NE02 IN TEST OR MAINTENANCE 1.034 Loss of Offsite Power SAMAs NE-DGN-FR-NE0112 DIESEL GENERATOR NE01 FTR - 12HR MT 1.033 Loss of Offsite Power SAMAs Callaway Plant Unit 1 Environmental Report for License Renewal F-28

Attachment F Severe Accident Mitigation Alternatives Table 3-7. Late Release Importance Review (Continued)

Basic Event Name Basic Event Description RRW Associated SAMA EF-MOV-CC-EFHV37 VALVE EFHV37 FAILS TO OPEN 1.032 Cooling Water SAMAs IE-S3 VERY SMALL LOCA INITIATING EVENT FREQUENCY 1.032 Safety Injection SAMAs NE-DGN-FR-NE0212 DIESEL GENERATOR NE02 FTR - 12HR MT 1.032 Loss of Offsite Power SAMAs NE-DGN-TM-NE01 DIESEL GEN NE01 IN TEST OR MAINTENANCE 1.032 Loss of Offsite Power SAMAs NE-DGN-FS-NE01 DIESEL GENERATOR NE01 FAILS TO START 1.03 Loss of Offsite Power SAMAs NON-TORNADO-T1 CONDITIONAL PROB. T(1) EVENT NOT CAUSED BY TORNADO 1.03 Loss of Offsite Power SAMAs VD-FAN-FR-CGD02A UHS C.T. ELEC. ROOMSUPPLY FAN CGD02A FAILS TO RUN 1.03 HVAC SAMAs NE-DGN-FS-NE02 DIESEL GENERATOR NE02 FAILS TO START 1.029 Loss of Offsite Power SAMAs OP-XHE-FO-DEP1 OPERATOR FAILS TO OPEN PORV TO DEPRESSURIZE RCS 1.029 See note on operator action events EF-MDP-DS-EFPMPS ESW PUMPS CC FTS. 1.028 Cooling Water SAMAs EF-MOV-CC-EFHV38 VALVE EFHV38 FAILS TO OPEN 1.028 Cooling Water SAMAs EF-MDP-FS-PEF01A ESW PUMP A (PEF01A)FAILS TO START 1.027 Cooling Water SAMAs EF-MDP-FS-PEF01B ESW PUMP B (PEF01B)FAILS TO START 1.027 Cooling Water SAMAs EF-MOV-D2-V37-38 COMMON CAUSE FAIL.-VALVES EF-HV-37 AND38 FTC. 1.027 Cooling Water SAMAs VD-FAN-FR-CGD02B UHS C.T. ELEC. ROOMSUPPLY FAN CGD02B FAILS TO RUN 1.026 HVAC SAMAs OP-XHE-FO-AEPS1 OPERATOR FAIL TO ALIGN AEPS TO NB BUS IN 1 HR 1.025 See note on operator action events FAILTOMNLINSRODS OPERATOR FAILS TO MANUALLY DRIVE RODSINTO CORE (RI). 1.023 ATWS SAMAs EF-MOV-OO-EFHV59 VALVE EFHV59 FAILS TO CLOSE 1.022 Cooling Water SAMAs FAILTOREC-EFHV59 OPERATORS FAIL TO RECOVER (CLOSE) EFHV59. 1.022 See note on operator action events BN-TNK-FC-RWSTUA RWST UNAVAILABLE 1.02 SAMA 171 AEPS-ALIGN-NB01 PDG ALIGN TO NB01 (FAIL TO ALIGN PDG TO NB02) 1.016 Loss of Offsite Power SAMAs AEPS-ALIGN-NB02 PDG ALIGN TO NB02 (FAIL TO ALIGN PDG TO NB01) 1.015 Loss of Offsite Power SAMAs AL-TDP-TM-TDAFP TDAFP IN TEST OR MAINTENANCE 1.015 AFW SAMAs IE-T2 LOSS OF MAIN FEEDWATER IE FREQUENCY 1.013 Feedwater SAMAs Callaway Plant Unit 1 Environmental Report for License Renewal F-29

Attachment F Severe Accident Mitigation Alternatives Table 3-7. Late Release Importance Review (Continued)

Basic Event Name Basic Event Description RRW Associated SAMA NF-ICC-AF-LSELSA LOAD SHEDDER TRAIN A FAILS TO SHED LOADS 1.013 Loss of Offsite Power SAMAs NF-ICC-AF-LSELSB LOAD SHEDDER TRAIN B FAILS TO SHED LOADS 1.013 Loss of Offsite Power SAMAs VM-BDD-CC-GMD001 DAMPER GMD001 FAILS TO OPEN 1.013 HVAC SAMAs VM-BDD-CC-GMD004 DAMPER GMD004 FAILS TO OPEN 1.013 HVAC SAMAs VM-BDD-CC-GMD006 DAMPER GMD006 FAILS TO OPEN 1.013 HVAC SAMAs VM-BDD-CC-GMD009 DAMPER GMD009 FAILS TO OPEN 1.013 HVAC SAMAs VM-EHD-CC-GMTZ11 ELEC/HYDR OP DAMPER GMTZ11A FAILS TO OPEN 1.013 HVAC SAMAs VM-EHD-CC-GMTZ1A ELEC/HYDR OP DAMPER GMTZ01A FAILS TO OPEN 1.013 HVAC SAMAs NE-DGN-FR-NE01-2 DGN NE02 FAILS TO RUN (1 HR MISSION TIME) 1.012 Loss of Offsite Power SAMAs NE-DGN-FR-NE02-2 DGN NE02 FAILS TO RUN (1 HR MISSION TIME) 1.011 Loss of Offsite Power SAMAs EF-CKV-DF-V01-04 CHECK VALVES EFV001 AND EFV004 COMMON CAUSE FAIL TO 1.009 Cooling Water SAMAs OPEN MANLRODINSERTION OPERATORS MANUALLY DRIVE RODS INTO THE CORE 1.009 ATWS SAMAs VM-FAN-FS-CGM01A DIESEL GEN SUPPLY FAN CGM01A FAILS TO START 1.009 HVAC SAMAs VM-FAN-FS-CGM01B DIESEL GEN SUPPLY FAN CGM01B FAILS TO START 1.009 HVAC SAMAs AE-CKV-DF-V124-7 CHECK VALVES AEV124,125,126,127 COMMON CAUSE FAIL TO 1.008 SAMA 163 OPEN AE-XHE-FO-MFWFLO FAILURE TO RE-ESTABLISH MFW FLOW DUE TO HUMAN 1.008 See note on operator action ERRORS events EG-AOV-DF-TV2930 COMMON CAUSE FAILURE EG-TV-29 AND 30 TO CLOSE 1.008 Cooling Water SAMAs EG-HTX-TM-CCWHXB CCW TRAIN B TEST/MAINT. (E.G. HX B TEST/MAINT.) 1.008 Cooling Water SAMAs IE-TFLB FEEDLINE BREAK DOWNSTREAM OF CKVS IE FREQUENCY 1.008 Feedwater SAMAs AL-TDP-FS-TDAFP TDAFP FAILS TO START 1.007 AFW SAMAs AL-XHE-FO-SBOSGL OPERATOR FAILS TO CONTROL S//G LEVEN AFTER COMPLEX 1.007 See note on operator action EVENT events IE-TSW LOSS OF SERVICE WATER INITIATING EVENT 1.007 Service Water SAMAs NB-BKR-CC-NB0112 BREAKER NB0112 FAILS TO OPEN 1.007 Loss of Offsite Power SAMAs Callaway Plant Unit 1 Environmental Report for License Renewal F-30

Attachment F Severe Accident Mitigation Alternatives Table 3-7. Late Release Importance Review (Continued)

Basic Event Name Basic Event Description RRW Associated SAMA NE-DGN-DS-NE01-2 DGNS CC FTS. 1.007 Loss of Offsite Power SAMAs BG-MDP-TM-CCPA CCP A IN TEST OR MAINTENANCE 1.006 Core Cooling SAMAs BG-MDP-TM-CCPB CCP B IN TEST OR MAINTENANCE 1.006 Core Cooling SAMAs EG-MDP-DS-EGPMP4 ALL 4 EG PUMPS CC FTS. 1.006 Cooling Water SAMAs IE-TMSO MAIN STEAMLINE BREAK OUTSIDE CTMT IE FREQUENCY 1.006 SAMA 153 NB-BKR-CC-NB0209 BREAKER NB0209 FAILS TO OPEN 1.006 Loss of Offsite Power SAMAs VD-FAN-FS-CGD02A UHS C.T. ELEC. ROOMSUPPLY FAN CGD02A FAILS TO START 1.006 HVAC SAMAs IE-TDCNK01 LOSS OF VITAL DC BUS NK01 INITIATING EVENT FREQUENCY 1.005 DC Power SAMAs OP-XHE-FO-CCWRHX OPERATOR FAILS TO INITIATE CCW FLOW TO THE RHR HXS 1.005 See note on operator action events OP-XHE-FO-ESW2HR OPERATOR FAILS TO START AND ALIGN ESW 2 HR AFTER SW 1.005 See note on operator action LOSS events VD-FAN-DR-GD02AB FANS CGD02A,B COMMON CAUSE FTS 1.005 HVAC SAMAs VD-FAN-FS-CGD02B UHS C.T. ELEC. ROOMSUPPLY FAN CGD02B FAILS TO START 1.005 HVAC SAMAs VM-FAN-DS-GMFANS FANS CGM01A,B COMMON CAUSE FTS 1.005 HVAC SAMAs UHS = ultimate heat sink; AEPS = alternate emergency power system; RWST = refueling water storage tank Note 1 - The current plant procedures and training meet current industry standards. There are no additional specific procedure improvements that could be identified that would affect the result of the HEP calculations. Therefore, no SAMA items were added to the plant specific list of SAMAs as a result of the human actions on the list of basic events with RRW greater than 1.005.

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Attachment F Severe Accident Mitigation Alternatives 3.3 MODEL REVIEW

SUMMARY

Discussion of Reviews Conducted on the Callaway PRA Since the IPE As discussed above, the Callaway internal events PRA has been updated a number of times, since the IPE, to maintain fidelity between the plant and the PRA model, and to make improvements to the model. Updates to the PRA are documented in calculation notes, revisions and addenda, which are each independently reviewed by a qualified individual.

The Callaway PRA has undergone a number of in-house, peer and other reviews since the IPE, including the following:

• A self-assessment of the PRA was conducted prior to the WOG PRA peer review.

• The WOG conducted a PRA peer review in October 2000.

• The WOG reviewed results from the Callaway PRA as part of a PRA cross-comparison performed for member plants to identify outlier PRA results prior to MSPI implementation.

• In 2006, Scientech performed a review of the Callaway PRA against the Supporting Requirements for Capability Category II of Reference 27.

• Since 2007, a number of risk-informed license amendments have been submitted to and approved by NRC for Callaway. These have included a one-time per train ESW Completion Time extension, a containment ILRT extension and a BOP ESFAS Completion Time extension. In addition, Callaway recently submitted a license amendment request for Technical Specification Initiative 5b, the Surveillance Frequency Control Program. For each of these risk-informed license amendment requests, Ameren submitted, and NRC staff reviewed, information to demonstrate technical adequacy of the Callaway PRA.

Results of the WOG Peer Review As noted above, the WOG conducted a peer review of the Callaway internal events PRA in October 2000. This review applied a grading system to the PRA elements, as follows:

Grade 1 - supports assessment of plant vulnerabilities Grade 2 - supports risk ranking applications Grade 3 - supports risk significance evaluations with deterministic input Grade 4 - provides primary basis for application.

The WOG review deemed all of the Callaway PRA elements to be Grade 3 (or contingent Grade 3), except for the HRA element, which was deemed to be Grade 2. The HRA has since been re-performed by Scientech to address the WOG peer review findings.

In addition, all but five significance-level A (expected impact to be significantly non-conservative) and B (expected impact to be non-conservative but small) Facts/Observations (F&Os) generated during the WOG peer review have been addressed in the PRA model used for the SAMA analysis. The open F&Os, and an assessment of their impact on this application, are summarized in Table 3-8.

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Attachment F Severe Accident Mitigation Alternatives Table 3-8. Open WOG F&Os Significance F&O No. Level F&O Description Disposition for SAMA Analysis IE-7 B Two ISLOCA issues: Neither of these ISLOCA issues

1. ISLOCA locations are limited to bears negatively on the SAMA only those scenarios where analysis. In addition, following containment may be bypassed. further investigation after the WOG

2. The ISLOCA quantification does peer review, issue 1 was deemed not correlate variables for basic by Callaway not to be valid.

events using the same failure rate.

ST-1 B The ISLOCA analysis did not use This finding is considered to be an current state of the art analysis to enhancement to the ISLOCA determine probability of low pressure analysis, and does not bear pipe failure upon overpressure, such negatively on the SAMA analysis.

as the approach indicated in references such as NUREG/CR-5102 or NUREG/CR-5744.

TH-3 B Consider preparing success criteria This is a documentation issue. No guidance for the PRA, to address issues were identified with the such items as overall success criteria actual success criteria utilized.

definition process, development of Therefore, this F&O does not success criteria for systems, etc. impact the SAMA analysis.

L2-1 A Address containment isolation failure The SAMA analysis used a newly and internal floods in the LERF updated Level 2 analysis. It did calculation. not use the evaluated Callaway LERF model. The newly updated Level 2 model used for the SAMA analysis included containment isolation failure. Internal flooding was considered in the SAMA analysis to be part of the external events adjustment factor.

L2-3 B The calculation of LERF is based on This is a documentation issue containment event tree split fractions. related to the original LERF The process simply multiplies the split analysis. The Level 2 analysis fractions together, resulting in an updated and used for the SAMA overall LERF split fraction for each analysis is an integrated model PDS. It is not obvious how the split that used the containment event fractions are related back to trees for evaluation of the Level 2 elementary phenomena or system risks.

failures.

PDS = plant damage state 3.4 LEVEL 3 PRA MODEL The Callaway Level 3 PRA model determines off-site dose and economic impacts of severe accidents based on the Level 1 PRA results, the Level 2 PRA results, atmospheric transport, mitigating actions, dose accumulation, early and latent health effects, and economic analyses.

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Attachment F Severe Accident Mitigation Alternatives The MELCOR Accident Consequence Code System (MACCS2) Version 1.13 was used to perform the calculations of the off-site consequences of a severe accident. This code is documented in NUREG/CR-6613 [22], Code Manual for MACCS2: Volumes 1 and 2.

Plant-specific release data included the time-dependent nuclide distribution of releases and release frequencies. The behavior of the population during a release (evacuation parameters) was based on plant and site-specific set points. These data were used in combination with site-specific meteorology to simulate the probability distribution of impact risks (both exposures and economic effects) to the surrounding 50-mile radius population as a result of the release accident sequences at Callaway.

The following sections describe input data for the MACCS2 analysis tool. The analyses are provided in References 24 and 25.

3.4.1 Population Distribution The SECPOP2000 code, documented in NUREG/CR-6525 [26], is one means of calculating most input data required for a MACCS2 SITE file. SECPOP2000 can utilize 1990 or 2000 census population data, and associated county economic data. For the Callaway analysis, the SECPOP2000 code was utilized to develop initial residential population estimates for each spatial element within the 50 mile region based on year 2000 census data. Transient population data was added for spatial elements within the 10-mile radius based on the Callaway evacuation time estimate study. The population data was projected to year 2044 using county growth estimates based on Missouri Office of Administration projections for 2030 [25].

Tables 3-9 and 3-10 identify the year 2044 projected population distribution. Data choices are consistent with industry guidance provided in NEI 05-01 [19].

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Attachment F Severe Accident Mitigation Alternatives Table 3-9. Projected Population Distribution Within A 10-Mile Radius(1), Year 2044 10-mile Sector 0-1 mile 1-2 miles 2-3 miles 3-4 miles 4-5 miles 5-10 miles Total N 7 7 80 215 87 319 715 NNE 10 31 80 80 109 415 725 NE 10 7 0 26 46 75 164 ENE 10 11 0 0 0 115 136 E 10 7 0 0 122 127 266 ESE 26 7 4 17 54 166 274 SE 10 7 0 73 102 182 374 SSE 7 7 6 0 0 192 212 S 0 0 5 4 0 1049 1058 SSW 0 81 0 80 16 103 280 SW 0 0 0 0 117 2153 2270 WSW 0 0 0 0 44 867 911 W 0 208 0 0 0 922 1130 WNW 0 88 133 131 161 1348 1861 NW 0 0 1 23 7 1249 1280 NNW 0 0 42 38 11 721 812 Total 90 461 351 687 876 10003 12468 Source: Reference 26.

(1)Population projection for 0-10 miles includes transients and residents, population projection for 10- 50 miles includes residents only Callaway Plant Unit 1 Environmental Report for License Renewal F-35

Attachment F Severe Accident Mitigation Alternatives Table 3-10. Projected Population Distribution Within A 50-Mile Radius(1), Year 2044 0-10 10-20 20-30 30-40 40-50 50-mile Sector miles miles miles miles miles Total N 715 1271 7292 1424 2032 12734 NNE 725 786 2636 2126 5998 12271 NE 164 897 3790 2002 4863 11716 ENE 136 524 4025 11736 69462 85883 E 266 1848 3012 35790 47655 88571 ESE 274 3305 3047 12246 60385 79257 SE 374 824 1515 6970 10021 19704 SSE 212 451 996 7274 5779 14712 S 1058 2079 1746 3970 3254 12107 SSW 280 2463 3003 2306 3393 11445 SW 2270 2030 18012 6068 4860 33240 WSW 911 9554 66454 15257 8762 100938 W 1130 3927 10536 3602 4538 23733 WNW 1861 9482 28025 183082 5077 227527 NW 1280 15516 3821 15557 7645 43819 NNW 812 3800 10098 7414 1601 23725 Total 12468 58757 168008 316824 245325 801382 Source: Reference 26.

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Attachment F Severe Accident Mitigation Alternatives 3.4.2 Economic Data MACCS2 requires certain site specific economic data (fraction of land devoted to farming, annual farm sales, fraction of farm sales resulting from dairy production, and property value of farm and non-farm land) for each of the 160 spatial elements. The site specific base case values are calculated using the economic data from the 2007 U.S. Department of Agriculture and from other data sources, such as the Bureau of Labor Statistics and Bureau of Economic Analysis, updated to May 2010 values using the Consumer Price Index (CPI). The calculation approach documented in NUREG/CR-6525 (SECPOP2000) was utilized to develop the regional economic data inputs, but the SECPOP2000 code was not utilized for this purpose because the embedded economic data files contain older data (i.e., 1997 U.S. Department of Agriculture).

In addition to these site specific values, generic economic data are utilized by MACCS2 to address costs associated with per diem living expenses (applied to owners of interdicted properties and relocated populations), relocation costs (for owners of interdicted properties),

and decontamination costs. For the Callaway base case, these generic costs are based on values used in the NUREG-1150 studies (as documented in the NUREG/CR-4551 series of reports), updated to May 2010 using the CPI (Table 3-11).

Callaway Plant Unit 1 Environmental Report for License Renewal F-37

Attachment F Severe Accident Mitigation Alternatives Table 3-11. Generic Economic Data Variable Description Callaway Value (1)

DPRATE Property depreciation rate (per yr.) 0.20 (2)

DSRATE Investment rate of return (per yr.) 0.07 (3)

EVACST Daily cost for a person who has been evacuated ($/person-day) $54 (3)

POPCST Population relocation cost ($/person) $10,000 (3)

RELCST Daily cost for a person who is relocated ($/person-day) $54 (3) Cost of farm decontamination for various levels of CDFRM (5) $1,125 & $2,500 decontamination ($/hectare)

(3) Cost of non-farm decontamination per resident person for $6,000 &

CDNFRM various levels of decontamination ($/person) $16,000 (3) (5)

DLBCST Average cost of decontamination labor ($/man-year) $70,000 (4)

VALWF Value of farm wealth ($/hectare) $6,448 (4)

VALWNF Value of non-farm wealth average in US ($/person) $217,394 (1)

NUREG/CR-4551 value.

(2)

NUREG/BR-0058 value.

(3)

NUREG/CR-4551 value, updated to May 2010 using the CPI.

(4)

VALWF0 and VALWNF are based on the 2007 Census of Agriculture, Bureau of Labor Statistics and Bureau of Economic Analysis data, updated to May 2010 using the CPI for the counties within 50 miles.

(5)

Decontamination Factors of 3 and 15 were used in the Callaway analysis, consistent with NUREG-1150 studies.

3.4.3 Nuclide Release Core inventory represents end-of-cycle values for Callaway operating at 3565 MWth (current licensed value). The estimated core inventory reflects the current and anticipated fuel management / burnup during the license renewal period. Inventory values are provided in Table 3-12. Source term release fractions and other release data are based on plant specific MAAP simulations. Releases are modeled to occur at mid-height of the containment, consistent with NEI 05-01 guidance. Three plumes are modeled as presented in Table 3-13. The NRC has found the use of MAAP reasonable and appropriate for the purposes of SAMA analysis.

Opponents in other proceedings have suggested that the source terms in NUREG-1465 should be used. However, the NUREG-1465 source term only addresses the release of radionuclides into containment. Releases into containment and releases into the environment are very different events, with significant differences in sequence progression, release pathways, and fission product deposition and removal mechanisms. Additionally, use of plant specific data (when available) is preferred to generic data. Thus, use of the NUREG-1465 source terms would be inappropriate.

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Attachment F Severe Accident Mitigation Alternatives Table 3-12. Callaway Core Inventory Nuclide Activity (Bq) Nuclide Activity (Bq)

Co-58 3.37E+16 Te-131m 5.15E+17 Co-60 2.58E+16 Te-132 5.08E+18 Kr-85 3.39E+16 I-131 3.58E+18 Kr-85m 9.39E+17 I-132 5.17E+18 Kr-87 1.80E+18 I-133 7.28E+18 Kr-88 2.54E+18 I-134 8.00E+18 Rb-86 7.41E+15 I-135 6.82E+18 Sr-89 3.49E+18 Xe-133 7.13E+18 Sr-90 2.66E+17 Xe-135 1.53E+18 Sr-91 4.27E+18 Cs-134 5.74E+17 Sr-92 4.63E+18 Cs-136 1.70E+17 Y-90 2.80E+17 Cs-137 3.64E+17 Y-91 4.49E+18 Ba-139 6.52E+18 Y-92 4.65E+18 Ba-140 6.32E+18 Y-93 5.37E+18 La-140 6.57E+18 Zr-95 6.06E+18 La-141 5.93E+18 Zr-97 5.99E+18 La-142 5.74E+18 Nb-95 6.09E+18 Ce-141 6.01E+18 Mo-99 6.52E+18 Ce-143 5.51E+18 Tc-99m 5.71E+18 Ce-144 4.30E+18 Ru-103 5.49E+18 Pr-143 5.39E+18 Ru-105 3.75E+18 Nd-147 2.39E+18 Ru-106 1.72E+18 Np-239 6.80E+19 Rh-105 3.41E+18 Pu-238 9.11E+15 Sb-127 3.81E+17 Pu-239 9.74E+14 Sb-129 1.14E+18 Pu-240 1.24E+15 Te-127 3.76E+17 Pu-241 4.39E+17 Te-127m 4.86E+16 Am-241 4.68E+14 Te-129 1.13E+18 Cm-242 1.43E+17 Te-129m 1.68E+17 Cm-244 9.26E+15 Table 3-13 provides a description of the release characteristics evaluated in this analysis.

Callaway Plant Unit 1 Environmental Report for License Renewal F-39

Attachment F Severe Accident Mitigation Alternatives Table 3-13. Callaway Source Term Release Summary Release Category LATE- LATE-LERF-IS LERF-CI LERF-CF LERF-SG LERF-ITR BMT COP INTACT LATE- LATE-MAAP Case LERF-IS LERF-CIa LERF-CFa LERF-SG LERF-ITR BMT COP INTACT Run Duration 48 48 48 48 48 96 72 48 Time after Scram when GE is declared (1) 3.1 20.9 20.9 37.9 20.9 20.5 21.0 22.4 Fission Product Group:

1) Noble Gases Total Release Fraction 1.00E+00 9.00E-01 8.70E-01 9.80E-01 9.90E-01 4.80E-01 9.00E-01 2.60E-04 Total Plume 1 Release Fraction 8.60E-1 2.80E-1 4.60E-1 9.10E-1 9.00E-1 1.00E-4 4.00E-4 1.40E-5 Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 23.50 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 27.50 Total Plume 2 Release Fraction 1.20E-1 4.30E-1 2.80E-1 7.00E-2 5.00E-2 3.30E-1 5.90E-1 6.90E-5 Start of Plume 2 Release (hr) 4.50 28.00 32.00 42.00 23.00 72.00 46.00 27.50 End of Plume 2 Release (hr) 7.50 38.00 40.00 45.00 30.00 82.00 56.00 34.00 Total Plume 3 Release Fraction 2.00E-2 1.90E-1 1.30E-1 0.00E+0 4.00E-2 1.50E-1 3.10E-1 1.77E-4 Start of Plume 3 Release (hr) 7.50 38.00 40.00 30.00 82.00 56.00 34.00 End of Plume 3 Release (hr) 15.00 48.00 48.00 40.00 92.00 66.00 40.00

2) CsI Total Release Fraction 5.00E-01 8.80E-02 1.00E-01 3.90E-01 2.70E-01 7.50E-04 2.80E-02 1.40E-05 Total Plume 1 Release Fraction 4.20E-1 2.40E-2 4.20E-2 3.70E-1 1.80E-1 4.00E-5 8.00E-3 3.40E-6 Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 23.50 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 27.50 Total Plume 2 Release Fraction 7.00E-2 3.20E-2 4.30E-2 2.00E-2 5.00E-2 5.80E-4 1.20E-2 9.60E-6 Start of Plume 2 Release (hr) 4.50 28.00 32.00 42.00 23.00 72.00 46.00 27.50 End of Plume 2 Release (hr) 7.50 38.00 40.00 45.00 30.00 82.00 56.00 34.00 Total Plume 3 Release Fraction 1.00E-2 3.20E-2 1.50E-2 0.00E+0 4.00E-2 1.30E-4 8.00E-3 1.00E-6 Callaway Plant Unit 1 Environmental Report for License Renewal F-40

Attachment F Severe Accident Mitigation Alternatives Table 3-13. Callaway Source Term Release Summary (Continued)

Release Category LATE- LATE-LERF-IS LERF-CI LERF-CF LERF-SG LERF-ITR BMT COP INTACT LATE- LATE-MAAP Case LERF-IS LERF-CIa LERF-CFa LERF-SG LERF-ITR BMT COP INTACT Start of Plume 3 Release (hr) 7.50 38.00 40.00 30.00 82.00 56.00 34.00 End of Plume 3 Release (hr) 15.00 48.00 48.00 40.00 92.00 66.00 40.00

3) TeO2 Total Release Fraction 5.80E-01 5.00E-02 5.50E-02 2.00E-01 2.60E-01 7.90E-05 7.00E-03 1.40E-05 Total Plume 1 Release Fraction 4.60E-1 2.40E-2 4.60E-2 1.90E-1 1.90E-1 2.70E-5 4.50E-3 2.50E-6 Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 23.50 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 27.50 Total Plume 2 Release Fraction 1.10E-1 2.40E-2 6.00E-3 1.00E-2 4.00E-2 4.30E-5 1.90E-3 9.50E-6 Start of Plume 2 Release (hr) 4.50 28.00 32.00 42.00 23.00 72.00 46.00 27.50 End of Plume 2 Release (hr) 7.50 38.00 40.00 45.00 30.00 82.00 56.00 34.00 Total Plume 3 Release Fraction 1.00E-2 2.00E-3 3.00E-3 0.00E+0 3.00E-2 9.00E-6 6.00E-4 2.00E-6 Start of Plume 3 Release (hr) 7.50 38.00 40.00 30.00 82.00 56.00 34.00 End of Plume 3 Release (hr) 15.00 48.00 48.00 40.00 92.00 66.00 40.00

4) SrO Total Release Fraction 4.90E-02 1.10E-03 1.10E-03 1.40E-03 2.10E-03 2.50E-05 7.90E-05 2.80E-07 Total Plume 1 Release Fraction 2.50E-2 9.70E-4 1.10E-3 1.40E-3 2.40E-4 5.00E-6 6.20E-5 2.80E-8 Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 23.50 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 27.50 Total Plume 2 Release Fraction 3.00E-3 1.30E-4 0.00E+0 0.00E+0 1.46E-3 1.40E-5 1.10E-5 1.92E-7 Start of Plume 2 Release (hr) 4.50 28.00 23.00 72.00 46.00 27.50 End of Plume 2 Release (hr) 7.50 38.00 30.00 82.00 56.00 34.00 Total Plume 3 Release Fraction 2.10E-2 0.00E+0 0.00E+0 0.00E+0 4.00E-4 6.00E-6 6.00E-6 6.00E-8 Start of Plume 3 Release (hr) 7.50 30.00 82.00 56.00 34.00 End of Plume 3 Release (hr) 15.00 40.00 92.00 66.00 40.00 Callaway Plant Unit 1 Environmental Report for License Renewal F-41

Attachment F Severe Accident Mitigation Alternatives Table 3-13. Callaway Source Term Release Summary (Continued)

Release Category LATE- LATE-LERF-IS LERF-CI LERF-CF LERF-SG LERF-ITR BMT COP INTACT LATE- LATE-MAAP Case LERF-IS LERF-CIa LERF-CFa LERF-SG LERF-ITR BMT COP INTACT

5) MoO2 Total Release Fraction 2.70E-02 1.80E-03 2.20E-03 5.00E-02 2.20E-02 3.70E-05 3.70E-04 2.30E-06 Total Plume 1 Release Fraction 1.90E-2 1.50E-3 1.60E-3 4.90E-2 1.90E-2 6.00E-6 1.50E-4 9.00E-7 Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 23.50 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 27.50 Total Plume 2 Release Fraction 6.00E-3 3.00E-4 3.00E-4 1.00E-3 3.00E-3 2.30E-5 8.00E-5 1.00E-6 Start of Plume 2 Release (hr) 4.50 28.00 32.00 23.00 72.00 46.00 27.50 End of Plume 2 Release (hr) 7.50 38.00 40.00 30.00 82.00 56.00 34.00 Total Plume 3 Release Fraction 2.00E-3 0.00E+0 3.00E-4 0.00E+0 0.00E+0 8.00E-6 1.40E-4 4.00E-7 Start of Plume 3 Release (hr) 7.50 40.00 82.00 56.00 34.00 End of Plume 3 Release (hr) 15.00 48.00 92.00 66.00 40.00

6) CsOH Total Release Fraction 4.90E-01 6.70E-02 8.60E-02 1.60E-01 2.10E-01 4.30E-04 2.50E-02 1.40E-05 Total Plume 1 Release Fraction 4.20E-1 1.20E-2 4.30E-2 1.50E-1 1.20E-1 2.00E-5 5.00E-3 3.30E-6 Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 23.50 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 27.50 Total Plume 2 Release Fraction 6.00E-2 4.10E-2 2.30E-2 1.00E-2 2.00E-2 3.20E-4 9.00E-3 8.70E-6 Start of Plume 2 Release (hr) 4.50 28.00 32.00 42.00 23.00 72.00 46.00 27.50 End of Plume 2 Release (hr) 7.50 38.00 40.00 45.00 30.00 82.00 56.00 34.00 Total Plume 3 Release Fraction 1.00E-2 1.40E-2 2.00E-2 0.00E+0 7.00E-2 9.00E-5 1.10E-2 2.00E-6 Start of Plume 3 Release (hr) 7.50 38.00 40.00 30.00 82.00 56.00 34.00 End of Plume 3 Release (hr) 15.00 48.00 48.00 40.00 92.00 66.00 40.00

7) BaO Total Release Fraction 6.50E-02 1.20E-03 1.20E-03 2.20E-02 5.80E-03 3.60E-05 2.70E-04 7.50E-07 Total Plume 1 Release Fraction 3.40E-2 1.10E-3 1.10E-3 2.20E-2 3.90E-3 5.00E-6 7.00E-5 1.90E-7 Callaway Plant Unit 1 Environmental Report for License Renewal F-42

Attachment F Severe Accident Mitigation Alternatives Table 3-13. Callaway Source Term Release Summary (Continued)

Release Category LATE- LATE-LERF-IS LERF-CI LERF-CF LERF-SG LERF-ITR BMT COP INTACT LATE- LATE-MAAP Case LERF-IS LERF-CIa LERF-CFa LERF-SG LERF-ITR BMT COP INTACT Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 23.50 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 27.50 Total Plume 2 Release Fraction 5.00E-3 1.00E-4 0.00E+0 0.00E+0 1.50E-3 2.20E-5 1.70E-4 4.30E-7 Start of Plume 2 Release (hr) 4.50 28.00 23.00 72.00 46.00 27.50 End of Plume 2 Release (hr) 7.50 38.00 30.00 82.00 56.00 34.00 Total Plume 3 Release Fraction 2.60E-2 0.00E+0 1.00E-4 0.00E+0 4.00E-4 9.00E-6 3.00E-5 1.30E-7 Start of Plume 3 Release (hr) 7.50 40.00 30.00 82.00 56.00 34.00 End of Plume 3 Release (hr) 15.00 48.00 40.00 92.00 66.00 40.00

8) La2O3 Total Release Fraction 1.10E-03 1.10E-03 1.10E-03 6.80E-05 1.60E-03 4.80E-06 7.90E-05 4.30E-09 Total Plume 1 Release Fraction 1.70E-4 9.70E-4 1.10E-3 6.80E-5 2.30E-5 4.70E-6 6.20E-5 5.00E-10 Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 23.50 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 27.50 Total Plume 2 Release Fraction 3.00E-5 1.30E-4 0.00E+0 0.00E+0 1.34E-3 1.00E-7 1.30E-5 2.90E-9 Start of Plume 2 Release (hr) 4.50 28.00 23.00 72.00 46.00 27.50 End of Plume 2 Release (hr) 7.50 38.00 30.00 82.00 56.00 34.00 Total Plume 3 Release Fraction 9.00E-4 0.00E+0 0.00E+0 0.00E+0 2.40E-4 0.00E+0 4.00E-6 9.00E-10 Start of Plume 3 Release (hr) 7.50 30.00 56.00 34.00 End of Plume 3 Release (hr) 15.00 40.00 66.00 40.00

9) CeO2 Total Release Fraction 3.70E-03 1.10E-03 1.10E-03 3.60E-04 1.80E-03 4.90E-06 1.00E-04 2.80E-08 Total Plume 1 Release Fraction 1.10E-3 9.70E-4 1.10E-3 3.60E-4 9.30E-5 4.70E-6 6.00E-5 3.00E-9 Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 23.50 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 27.50 Total Plume 2 Release Fraction 5.00E-4 1.30E-4 0.00E+0 0.00E+0 1.36E-3 2.00E-7 2.00E-5 2.10E-8 Callaway Plant Unit 1 Environmental Report for License Renewal F-43

Attachment F Severe Accident Mitigation Alternatives Table 3-13. Callaway Source Term Release Summary (Continued)

Release Category LATE- LATE-LERF-IS LERF-CI LERF-CF LERF-SG LERF-ITR BMT COP INTACT LATE- LATE-MAAP Case LERF-IS LERF-CIa LERF-CFa LERF-SG LERF-ITR BMT COP INTACT Start of Plume 2 Release (hr) 4.50 28.00 23.00 72.00 46.00 27.50 End of Plume 2 Release (hr) 7.50 38.00 30.00 82.00 56.00 34.00 Total Plume 3 Release Fraction 2.10E-3 0.00E+0 0.00E+0 0.00E+0 3.50E-4 0.00E+0 2.00E-5 4.00E-9 Start of Plume 3 Release (hr) 7.50 30.00 56.00 34.00 End of Plume 3 Release (hr) 15.00 40.00 66.00 40.00

10) Sb (Grouped with TeO2)

Total Release Fraction 2.60E-01 1.60E-02 1.80E-02 9.80E-02 1.50E-01 3.20E-04 2.30E-03 5.40E-06 Total Plume 1 Release Fraction 1.50E-01 1.10E-02 9.80E-03 9.70E-02 1.20E-01 2.00E-05 1.10E-03 1.10E-06 Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 23.50 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 27.50 Total Plume 2 Release Fraction 2.00E-02 2.00E-03 4.20E-03 1.00E-03 2.00E-02 2.00E-04 1.00E-03 3.40E-06 Start of Plume 2 Release (hr) 4.50 28.00 32.00 42.00 23.00 72.00 46.00 27.50 End of Plume 2 Release (hr) 7.50 38.00 40.00 45.00 30.00 82.00 56.00 34.00 Total Plume 3 Release Fraction 9.00E-02 3.00E-03 4.00E-03 0.00E+00 1.00E-02 1.00E-04 2.00E-04 9.00E-07 Start of Plume 3 Release (hr) 7.50 38.00 40.00 30.00 82.00 56.00 34.00 End of Plume 3 Release (hr) 15.00 48.00 48.00 40.00 92.00 66.00 40.00

11) Te2 (Grouped with TeO2)

Total Release Fraction 3.80E-04 1.10E-05 1.10E-05 6.00E-07 2.90E-04 3.30E-06 1.20E-05 0.00E+00 Total Plume 1 Release Fraction 0.00E+00 3.20E-06 3.70E-06 0.00E+00 0.00E+00 1.00E-07 1.70E-06 0.00E+00 Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 Total Plume 2 Release Fraction 9.00E-05 2.50E-06 3.00E-06 6.00E-07 3.20E-05 2.10E-06 6.30E-06 0.00E+00 Start of Plume 2 Release (hr) 4.50 28.00 32.00 42.00 23.00 72.00 46.00 End of Plume 2 Release (hr) 7.50 38.00 40.00 45.00 30.00 82.00 56.00 Total Plume 3 Release Fraction 2.90E-04 5.30E-06 4.30E-06 0.00E+00 2.58E-04 1.10E-06 4.00E-06 0.00E+00 Callaway Plant Unit 1 Environmental Report for License Renewal F-44

Attachment F Severe Accident Mitigation Alternatives Table 3-13. Callaway Source Term Release Summary (Continued)

Release Category LATE- LATE-LERF-IS LERF-CI LERF-CF LERF-SG LERF-ITR BMT COP INTACT LATE- LATE-MAAP Case LERF-IS LERF-CIa LERF-CFa LERF-SG LERF-ITR BMT COP INTACT Start of Plume 3 Release (hr) 7.50 38.00 40.00 30.00 82.00 56.00 End of Plume 3 Release (hr) 15.00 48.00 48.00 40.00 92.00 66.00

12) UO2 (Grouped with CeO2)

Total Release Fraction 6.10E-06 6.90E-10 4.60E-10 3.30E-10 3.10E-07 2.20E-09 3.00E-11 0.00E+00 Total Plume 1 Release Fraction 0.00E+00 6.10E-10 4.50E-10 0.00E+00 0.00E+00 1.00E-10 2.70E-11 0.00E+00 Start of Plume 1 Release (hr) 3.10 22.00 23.50 38.00 21.00 22.00 23.00 End of Plume 1 Release (hr) 4.50 28.00 32.00 42.00 23.00 32.00 33.00 Total Plume 2 Release Fraction 1.10E-06 8.00E-11 1.00E-11 3.30E-10 3.00E-08 1.70E-09 3.00E-12 0.00E+00 Start of Plume 2 Release (hr) 4.50 28.00 32.00 42.00 23.00 72.00 46.00 End of Plume 2 Release (hr) 7.50 38.00 40.00 45.00 30.00 82.00 56.00 Total Plume 3 Release Fraction 5.00E-06 0.00E+00 0.00E+00 0.00E+00 2.80E-07 4.00E-10 0.00E+00 0.00E+00 Start of Plume 3 Release (hr) 7.50 30.00 82.00 End of Plume 3 Release (hr) 15.00 40.00 92.00 Callaway Plant Unit 1 Environmental Report for License Renewal F-45

Attachment F Severe Accident Mitigation Alternatives 3.4.4 Emergency Response A reactor trip signal begins each evaluated accident sequence. A General Emergency is declared when plant conditions degrade to the point where it is judged that there is a credible risk to the public. Therefore, the timing of the General Emergency declaration is sequence specific and declaration ranges from 1 to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for the release sequences evaluated.

Evacuation parameters included in the file are based on the evacuation time estimate study for the Callaway Plant. Protective action parameters for the EARLY phase are based on the protective action guides (PAGs) specified in EPA-400. Data choices are consistent with guidance provided in NEI 05-01 [19]. In the modeling, 95% of the population is assumed to evacuate the 10 mile region of the emergency planning zone (EPZ) radially at an average speed of 2.14 meters/second, starting 105 minutes after the declaration of general emergency. The evacuation time estimate study presents evacuation times for normal and adverse weather conditions for an evacuation occurring in the daytime on a winter weekday. A daytime winter weekday evacuation was judged in the time estimate study to be conservative compared to other potential time periods (e.g., nighttime, summer, weekend). For the Level 3 analysis, the evacuation speed is time weighted average assuming normal weather conditions 90% of the time and adverse weather conditions 10% of the time.

Two evacuation sensitivity cases were performed. The first sensitivity case evaluated the impact of an increased delay time before evacuation begins (i.e., vehicles begin moving in the 10 mile region). For this sensitivity, the base case delay time of 105 minutes is doubled to 210 minutes. The increased delay time results in an increase in dose risk of about 2.4%. The second sensitivity case assessed the impact of evacuation speed assumptions by reducing the evacuation speed by one half, to 1.0 7 m/s (2.4 mph). The slower evacuation speed increases the dose risk by approximately 7%.

3.4.5 Meteorological Data Each year of meteorological data consists of 8,760 weather data sets of hourly recordings of wind direction, wind speed, atmospheric stability, and accumulated precipitation Site-specific weather data was obtained from the Callaway on-site meteorological monitoring system for years 2007 through 2009. MACCS2 does not permit missing data, so bad or missing data were filled in by using interpolation, substituting data from the previous or subsequent day, or using precipitation data from the Prairie Fork Conservation area (9.5 miles NNE). The 2008 data set was found to be the most complete (<0.1% data voids) and also result in the largest economic cost risk and dose risk compared to the 2007 and 2009 data sets. Because the MACCS2 code can only process one year of meteorological data at a time, the 2008 data was conservatively selected for the base case analysis.

Studies have shown that the Gaussian plume model (ATMOS) used in MACCS2 compares well against more complex variable trajectory transport and dispersion models. NUREG/CR-6853, Molenkamp et al., Comparison of Average Transport and Dispersion Among a Gaussian, a Two-Dimensional, and a Three-Dimensional Model (Oct. 2004) compared MACCS2 with two Gaussian puff models (RASCAL and RATCHET) developed by Pacific Northwest National Laboratory, and a state-of-the-art Lagrangian particle model (LODI) developed by Lawrence Livermore National Laboratory. These models were compared using one year of hourly-observed meteorological data from many weather sites in a large domain in the Midwest, referred to as the Southern Great Plains, centered on Oklahoma and Kansas. The study found Callaway Plant Unit 1 Environmental Report for License Renewal F-46

Attachment F Severe Accident Mitigation Alternatives that [n]early all the annual average ring exposures and depositions and a great majority of the arc sector values for MACCS2, RASCAL, and RATCHET are within a factor of two of the corresponding ADAPT/LODI values. Indeed, the largest observed deviation between mean results produced by MACCS2 and LODI was 58%. In comparison, the largest observed deviation between RASCAL and LODI was 61%. When averaged over a series of radial arcs out to fifty miles, MACCS2 was within plus or minus 10% of the three dimensional model. The Midwest terrain and meteorological data used in this study is very representative of Callaway.

Similarly, a more recent comparison of MACCS2 against another Lagrangian puff model (CALMET, the meteorological processor in CALPUFF) using data from multiple meteorological stations showed that consideration of time and spatially variable wind fields would have less than a 4% impact on the SAMA analysis in the Pilgrim license renewal proceeding, notwithstanding the existence of a sea breeze phenomenon at that facility. Thus, MACCS2 appears well suited for estimating mean offsite consequences for use in SAMA analysis, and particularly appropriate for Callaway given the results of the Molenkamp study and the simple terrain in the vicinity of the plant.

3.5 SEVERE ACCIDENT RISK RESULTS Using the MACCS2 code, the dose and economic costs associated with a severe accident at Callaway were calculated for each of the years for which meteorological data was gathered.

This information is provided below in Table 3-14 and Table 3-15, respectively. The results for year 2008 were used since the 2008 data resulted in the highest cost/year.

Table 3-14. Dose and Cost Results by Source Term (0-50 Mile Radius from Callaway Site)

Source Frequency Dose Dose Risk Total Cost Cost Risk Term (per yr.) (p-rem) (p-rem/year) ($) ($/yr.)

LERF-IS 1.73E-07 2.00E+06 3.46E-01 8.22E+09 1.42E+03 LERF-CI 1.66E-10 7.66E+05 1.27E-04 4.80E+09 7.96E-01 LERF-CF 1.13E-08 8.24E+05 9.27E-03 5.49E+09 6.18E+01 LERF-SG 2.33E-06 9.13E+05 2.13E+00 4.92E+09 1.15E+04 LERF-ITR 2.17E-07 1.23E+06 2.67E-01 8.01E+09 1.74E+03 LATE-BMT 2.55E-06 3.89E+04 9.92E-02 4.91E+07 1.25E+02 LATE-COP 3.19E-06 5.41E+05 1.72E+00 1.86E+09 5.92E+03 INTACT 8.08E-06 2.86E+03 2.31E-02 1.25E+06 1.01E+01 Total 1.66E-05 -- 4.60E+00 -- 2.08E+04 p = person Callaway Plant Unit 1 Environmental Report for License Renewal F-47

Attachment F Severe Accident Mitigation Alternatives Table 3-15. Ingestion Dose by Source Term (0-50 Mile Radius from Callaway site)

Food Food Water Water Ingestion Ingestion Source Frequency Dose Dose Risk Dose Dose Risk Dose Dose Risk Term (per yr.) (p-rem) (p-rem/yr.) (p-rem) (p-rem/yr.) (p-rem) (p-rem/yr.)

LERF-IS 1.73E-07 1.43E+05 2.47E-02 1.27E+05 2.20E-02 2.70E+05 4.67E-02 LERF-CI 1.66E-10 6.38E+04 1.06E-05 1.44E+04 2.39E-06 7.82E+04 1.30E-05 LERF-CF 1.13E-08 6.55E+04 7.37E-04 1.82E+04 2.05E-04 8.37E+04 9.42E-04 LERF-SG 2.33E-06 4.61E+04 1.07E-01 3.32E+04 7.74E-02 7.93E+04 1.85E-01 LERF-ITR 2.17E-07 7.30E+04 1.58E-02 4.40E+04 9.55E-03 1.17E+05 2.54E-02 LATE-BMT 2.55E-06 2.14E+04 5.46E-02 1.01E+02 2.58E-04 2.15E+04 5.48E-02 LATE-COP 3.19E-06 6.43E+04 2.05E-01 5.17E+03 1.65E-02 6.95E+04 2.21E-01 INTACT 8.08E-06 2.21E+03 1.79E-02 3.03E+00 2.45E-05 2.21E+03 1.79E-02 Total 1.66E-05 -- 4.26E-01 -- 1.26E-01 -- 5.52E-01 p = person 4.0 COST OF SEVERE ACCIDENT RISK / MAXIMUM BENEFIT Cost/benefit evaluation of SAMAs is based upon the cost of implementation of a SAMA compared to the averted onsite and offsite costs resulting from the implementation of that SAMA. The methodology used for this evaluation was based upon the NRCs guidance for the performance of cost-benefit analyses [15]. This guidance involves determining the net value for each SAMA according to the following formula:

Net Value = (APE + AOC + AOE + AOSC) - COE Where APE = present value of averted public exposure ($)

AOC = present value of averted offsite property damage costs ($)

AOE = present value of averted occupational exposure ($)

AOSC = present value of averted onsite costs ($)

COE = cost of enhancement ($).

If the net value of a SAMA is negative, the cost of implementing the SAMA is larger than the benefit associated with the SAMA and is not considered beneficial. The derivation of each of these costs is described in below.

The following specific values were used for various terms in the analyses:

Present Worth The present worth was determined by:

1 e rt PW =

r Where:

r is the discount rate = 7% (assumed throughout these analyses) t is the duration of the license renewal = 20 years PW is the present worth of a string of annual payments = 10.76 Callaway Plant Unit 1 Environmental Report for License Renewal F-48

Attachment F Severe Accident Mitigation Alternatives Dollars per rem The conversion factor used for assigning a monetary value to on-site and off-site exposures was $2,000/person-rem averted. This is consistent with the NRCs regulatory analysis guidelines presented in and used throughout NUREG/BR-0184, Reference 20.

On-site Person-rem per Accident The occupational exposure associated with severe accidents was assumed to be 23,300 person-rem/accident. This value includes a short-term component of 3,300 person-rem/accident and a long-term component of 20,000 person-rem/accident. These estimates are consistent with the best estimate values presented in Section 5.7.3 of Reference 15. In the cost/benefit analyses, the accident-related on-site exposures were calculated using the best estimate exposure components applied over the on-site cleanup period.

On-site Cleanup Period In the cost/benefit analyses, the accident-related on-site exposures were calculated over a 10-year cleanup period.

Present Worth On-site Cleanup Cost per Accident The estimated cleanup cost for severe accidents was assumed to be

$1.5E+09/accident (undiscounted). This value was derived by the NRC in Reference 15, Section 5.7.6.1, Cleanup and Decontamination. This cost is the sum of equal annual costs over a 10-year cleanup period. At a 7% discount rate, the present value of this stream of costs is $1.1E+09.

4.1 OFF-SITE EXPOSURE COST Accident-Related Off-Site Dose Costs Offsite doses were determined using the MACCS2 model developed for Callaway Plant. Costs associated with these doses were calculated using the following equation:

rt

(

APE = FS D PS FA D PA R) 1 e f r

(1) where:

APE = monetary value of accident risk avoided due to population doses, after discounting R = monetary equivalent of unit dose ($/person-rem)

F = accident frequency (events/yr)

D P = population dose factor (person-rems/event)

S = status quo (current conditions)

A = after implementation of proposed action r = real discount rate t f = analysis period (years).

Using the values for r, t f , and R given above:

(

APE = ($2.15E + 4 ) FS DPS FA DPA )

Callaway Plant Unit 1 Environmental Report for License Renewal F-49

Attachment F Severe Accident Mitigation Alternatives 4.2 OFF-SITE ECONOMIC COST Offsite damage was determined using the MACCS2 model developed for Callaway Plant. Costs associated with these damages were calculated using the following equation:

rt f

(

AOC = FS PDS FA PDA )1 er where:

AOC = monetary value of accident risk avoided due to offsite property damage, after discounting F = accident frequency (events/yr)

PD = offsite property loss factor (dollars/event)

R = real discount rate tf = analysis period (years).

4.3 ON-SITE EXPOSURE COST Methods for calculating averted costs associated with onsite accident dose costs are as follows:

Immediate Doses (at time of accident and for immediate management of emergency)

For the case where the plant is in operation, the equations in Reference 15 can be expressed as:

rt f WIO = (F D S IOS FA DIO A )R 1 er (1)

Where:

W IO = monetary value of accident risk avoided due to immediate doses, after discounting R = monetary equivalent of unit dose, ($/person-rem)

F = accident frequency (events/yr)

D IO = immediate occupational dose (person-rems/event)

S = status quo (current conditions)

A = after implementation of proposed action r = real discount rate tf = analysis period (years).

The values used are:

R = $2000/person rem r = .07 D IO = 3,300 person-rems /accident (best estimate)

The license extension time of 20 years is used for t f.

Callaway Plant Unit 1 Environmental Report for License Renewal F-50

Attachment F Severe Accident Mitigation Alternatives For the basis discount rate, assuming F A is zero, the best estimate of the limiting savings is:

rt f

(

WIO = FS DIOS R ) 1 e r

1 e .07* 20

= 3300

• F * $2000 *

.07

= F * $6,600,000

• 10.763

= F * $0.71E + 8 , ($).

Long-Term Doses (process of cleanup and refurbishment or decontamination)

For the case where the plant is in operation, the equations in Reference 15 can be expressed as:

rt f 1 e rm

( )

W LTO = FS D LTOS FA D LTO A R

• 1 e r

• rm (2) where:

W IO = monetary value of accident risk avoided long term doses, after discounting

$

m = years over which long-term doses accrue.

The values used are:

R = $2000/person rem r = .07 D LTO = 20,000 person-rem /accident (best estimate) m = as long as 10 years The license extension period of 20 years is used for t f.

For the discount rate of 7%, assuming F A is zero, the best estimate of the limiting savings is rt f 1 e rm

( )

W LTO = FS D LTOS R

• 1 e r

• rm 1 e .07* 20 1 e .07* 10

= (FS 20000 )$2000 * *

.07 .07

• 10

= FS * $40,000,000

• 10.763

• 0.719

= FS * $3.10E + 8 , ($).

Total Accident-Related Occupational (On-site) Exposures Combining equations (1) and (2) above, using delta () to signify the difference in accident frequency resulting from the proposed actions, and using the above numerical values, the best-estimate, long term accident related on-site (occupational) exposure avoided (AOE) is:

AOE = WIO + WLTO = F * $(0.71 + 3.1)E + 8 = F * $3.81E + 8 ($)

Callaway Plant Unit 1 Environmental Report for License Renewal F-51

Attachment F Severe Accident Mitigation Alternatives 4.4 ON-SITE ECONOMIC COST Methods for calculation of averted costs associated with accident-related on-site property damage are as follows:

Cleanup/Decontamination Reference 15 assumes a total cleanup/decontamination cost of $1.5E+9 as a reasonable estimate and this same value was adopted for these analyses. Considering a 10-year cleanup period, the present value of this cost is:

C 1 e rm PVCD = CD

m r Where PV CD = present value of the cost of cleanup/decontamination C CD = total cost of the cleanup/decontamination effort m = cleanup period r = discount rate Based upon the values previously assumed:

$1.5E + 9 1 e

.07* 10 PVCD =

10 .07

PVCD = $1.079E + 9 This cost is integrated over the term of the proposed license extension as follows rt f 1 e U CD = PVCD r

Based upon the values previously assumed:

U CD = $1.079E + 9 [10.763]

U CD = $1.161E + 10 Replacement Power Costs Replacement power costs, U RP , are an additional contributor to onsite costs. These are calculated in accordance with NUREG/BR-0184, Section 5.6.7.2. 1 Since replacement power will be needed for that time period following a severe accident, for the remainder of the expected generating plant life, long-term power replacement calculations have been used. The calculations are based on the 910 MWe reference plant, and are appropriately scaled for the 1236 MWe Callaway Plant. The present value of replacement power is calculated as follows:

1 The section number for Section 5.6.7.2 apparently contains a typographical error. This section is a subsection of 5.7.6 and follows 5.7.6.1. However, the section number as it appears in the NUREG will be used in this document.

Callaway Plant Unit 1 Environmental Report for License Renewal F-52

Attachment F Severe Accident Mitigation Alternatives (Ratepwr)

($1.2E + 8 )

PVRP =

r (910 MWe)

(1 e f rt

)2

Where PV RP = Present value of the cost of replacement power for a single event.

tf = Analysis period (years).

r = Discount rate.

Ratepwr = Rated power of the unit The $1.2E+8 value has no intrinsic meaning but is a substitute for a string of non-constant replacement power costs that occur over the lifetime of a generic reactor after an event (from Reference 15). This equation was developed per NUREG/BR-0184 for discount rates between 5% and 10% only.

For discount rates between 1% and 5%, Reference 15 indicates that a linear interpolation is appropriate between present values of $1.2E+9 at 5% and $1.6E+9 at 1%. So for discount rates in this range the following equation was used to perform this linear interpolation.

[($1.6E + 9 ) - ($1.2E + 9 )] Ratepwr PVRP = ($1.6E + 9 ) - * [ rs - 1% ]

[5% - 1%] 910 MWe Where r s = Discount rate (small), between 1% and 5%.

Ratepwr = Rated power of the unit To account for the entire lifetime of the facility, U RP was then calculated from PV RP , as follows:

U RP =

PV RP r

( rt 1 e f )2 Where U RP = Present value of the cost of replacement power over the life of the facility.

Again, this equation is only applicable in the range of discount rates from 5% to 10%.

NUREG/BR-0184 states that for lower discount rates, linear interpolations for U RP are recommended between $1.9E+10 at 1% and $1.2E+10 at 5%. The following equation was used to perform this linear interpolation:

[($1.9E + 10 ) - ($1.2E + 10 )] Ratepwr U RP = ($1.9E + 10 ) - * [ rs - 1% ]

[5% - 1%] 910 MWe Callaway Plant Unit 1 Environmental Report for License Renewal F-53

Attachment F Severe Accident Mitigation Alternatives Where r s = Discount rate (small), between 1% and 5%.

Ratepwr = Rated power of the unit c) Repair and Refurbishment It is assumed that the plant would not be repaired/refurbished. Therefore, there is no contribution to averted onsite costs from this source.

d) Total Onsite Property Damage Costs The net present value of averted onsite damage costs is, therefore:

AOSC = F * (U CD + U RP )

Where F = Annual frequency of the event.

4.5 TOTAL COST OF SEVERE ACCIDENT RISK / MAXIMUM BENEFIT Cost/benefit evaluation of the maximum benefit is baseline risk of the plant converted dollars by summing the contributors to cost.

Maximum Benefit Value = (APE + AOC + AOE + AOSC) where APE = present value of averted public exposure ($),

AOC = present value of averted offsite property damage costs ($),

AOE = present value of averted occupational exposure ($),

AOSC = present value of averted onsite costs ($)

For Callaway Plant, based on the internal events PRA this value is $698,101 as shown in Table 4-1.

Table 4-1. Contributions to Maximum Averted Cost Risk Parameter Present Dollar Value ($)

Averted Public Exposure $98,930 Averted offsite costs $223,382 Averted occupational exposure $6300 Averted onsite costs $369,549 Total (Maximum Averted Cost Risk - MACR) $698,161 This internal events MACR is multiplied by 4.57 to account for external event and internal flooding contributions not included in the internal events PRA (Section 3.1.2.4). The resulting modified MACR is $3,192,773. This value was used for the SAMA screening and sensitivity analyses.

Callaway Plant Unit 1 Environmental Report for License Renewal F-54

Attachment F Severe Accident Mitigation Alternatives 5.0 SAMA IDENTIFICATION A list of SAMA candidates was developed by reviewing the major contributors to CDF and population dose based on the plant-specific risk assessment and the standard pressurized water reactor (PWR) list of enhancements from Reference 19 (NEI 05-01). Other recent license renewal applications (including Wolf Creek) were also reviewed to identify any applicable SAMA items for consideration. This section discusses the SAMA selection process and its results.

5.1 PRA IMPORTANCE The top core damage sequences and the components/systems having the greatest potential for risk reduction were examined to determine whether additional SAMAs could be identified from these sources.

Use of Importance Measures RRW of the basic events in the baseline model was used to identify those basic events that could have a significant potential for reducing risk. Basic Events with RRW >1.02 were identified as the most important. The basic events were reviewed to ensure that each basic event on the importance lists is covered by an existing SAMA item or added to the list if not.

5.2 PLANT IPE The Callaway Plant PRA identified no potential vulnerabilities. However, a number of plant modifications and procedure changes to reduce risk were identified. The Callaway Plant potential enhancements are listed in Table 5-1.

5.3 PLANT IPEEE Potential improvements to reduce seismic risk and risk from other external events were evaluated in the Callaway Plant IPEEE. These items are included in Table 5-1.

5.4 INDUSTRY SAMA CANDIDATES The generic PWR enhancement list from Table 14 of Reference 19 was included in the list of Phase I SAMA candidates to assure adequate consideration of potential enhancements identified by other industry studies.

5.5 PLANT STAFF INPUT TO SAMA CANDIDATES The Callaway plant staff provided plant specific items that were included in the evaluation.

These are identified in the list of SAMA candidates by their source.

5.6 LIST OF PHASE I SAMA CANDIDATES Table 5-1 provides the combined list of potential SAMA candidates considered in the Callaway Plant SAMA analysis. From this table it can be seen that 171 SAMA candidates were identified for consideration.

Callaway Plant Unit 1 Environmental Report for License Renewal F-55

Attachment F Severe Accident Mitigation Alternatives Table 5-1. List of SAMA Candidates.

Callaway SAMA Focus of Number Potential Improvement Discussion SAMA Source 1 Provide additional DC battery capacity. Extended DC power availability during an SBO station AC/DC 1 blackout (SBO).

2 Replace lead-acid batteries with fuel cells. Extended DC power availability during an SBO. AC/DC 1 3 Add additional battery charger or portable, diesel-driven battery Improved availability of DC power system. AC/DC 1 charger to existing DC system.

4 Improve DC bus load shedding. Extended DC power availability during an SBO. AC/DC 1 5 Provide DC bus cross-ties. Improved availability of DC power system. AC/DC 1 6 Provide additional DC power to the 120/240V vital AC system. Increased availability of the 120 V vital AC bus. AC/DC 1 7 Add an automatic feature to transfer the 120V vital AC bus from Increased availability of the 120 V vital AC bus. AC/DC 1 normal to standby power.

8 Increase training on response to loss of two 120V AC buses which Improved chances of successful response to loss of two AC/DC 1 causes inadvertent actuation signals. 120V AC buses.

9 Provide an additional diesel generator. Increased availability of on-site emergency AC power. AC/DC 1 10 Revise procedure to allow bypass of diesel generator trips. Extended diesel generator operation. AC/DC 1 11 Improve 4.16-kV bus cross-tie ability. Increased availability of on-site AC power. AC/DC 1 12 Create AC power cross-tie capability with other unit (multi-unit site) Increased availability of on-site AC power. AC/DC 1 13 Install an additional, buried off-site power source. Reduced probability of loss of off-site power. AC/DC 1 14 Install a gas turbine generator. Increased availability of on-site AC power. AC/DC 1 15 Install tornado protection on gas turbine generator. Increased availability of on-site AC power. AC/DC 1 16 Improve uninterruptible power supplies. Increased availability of power supplies supporting front- AC/DC 1 line equipment.

17 Create a cross-tie for diesel fuel oil (multi-unit site). Increased diesel generator availability. AC/DC 1 18 Develop procedures for replenishing diesel fuel oil. Increased diesel generator availability. AC/DC 1 19 Use fire water system as a backup source for diesel cooling. Increased diesel generator availability. AC/DC 1 20 Add a new backup source of diesel cooling. Increased diesel generator availability. AC/DC 1 21 Develop procedures to repair or replace failed 4 KV breakers. Increased probability of recovery from failure of breakers AC/DC 1 that transfer 4.16 kV non-emergency buses from unit station service transformers.

22 In training, emphasize steps in recovery of off-site power after an Reduced human error probability during off-site power AC/DC 1 SBO. recovery.

23 Develop a severe weather conditions procedure. Improved off-site power recovery following external AC/DC 1 weather-related events.

24 Bury off-site power lines. Improved off-site power reliability during severe AC/DC 1 weather.

25 Install an independent active or passive high pressure injection Improved prevention of core melt sequences. Core 1 system. Cooling Callaway Plant Unit 1 Environmental Report for License Renewal F-56

Attachment F Severe Accident Mitigation Alternatives Table 5-1. List of SAMA Candidates (Continued).

Callaway SAMA Focus of Number Potential Improvement Discussion SAMA Source 26 Provide an additional high pressure injection pump with independent Reduced frequency of core melt from small LOCA and Core 1 diesel. SBO sequences. Cooling 27 Revise procedure to allow operators to inhibit automatic vessel Extended HPCI and RCIC operation. Core 1 depressurization in non-ATWS scenarios. Cooling 28 Add a diverse low pressure injection system. Improved injection capability. Core 1 Cooling 29 Provide capability for alternate injection via diesel-driven fire pump. Improved injection capability. Core 1 Cooling 30 Improve ECCS suction strainers. Enhanced reliability of ECCS suction. Core 1 Cooling 31 Add the ability to manually align emergency core cooling system Enhanced reliability of ECCS suction. Core 1 recirculation. Cooling 32 Add the ability to automatically align emergency core cooling system Enhanced reliability of ECCS suction. Core 1 to recirculation mode upon refueling water storage tank depletion. Cooling 33 Provide hardware and procedure to refill the reactor water storage Extended reactor water storage tank capacity in the Core 1 tank once it reaches a specified low level. event of a steam generator tube rupture (or other Cooling LOCAs challenging RWST capacity).

34 Provide an in-containment reactor water storage tank. Continuous source of water to the safety injection Core 1 pumps during a LOCA event, since water released from Cooling a breach of the primary system collects in the in-containment reactor water storage tank, and thereby eliminates the need to realign the safety injection pumps for long-term post-LOCA recirculation.

35 Throttle low pressure injection pumps earlier in medium or large- Extended reactor water storage tank capacity. Core 1 break LOCAs to maintain reactor water storage tank inventory. Cooling 36 Emphasize timely recirculation alignment in operator training. Reduced human error probability associated with Core 1 recirculation failure. Cooling 37 Upgrade the chemical and volume control system to mitigate small For a plant like the Westinghouse AP600, where the Core 1 LOCAs. chemical and volume control system cannot mitigate a Cooling small LOCA, an upgrade would decrease the frequency of core damage.

38 Change the in-containment reactor water storage tank suction from Reduced common mode failure of injection paths. Core 1 four check valves to two check and two air-operated valves. Cooling 39 Replace two of the four electric safety injection pumps with diesel- Reduced common cause failure of the safety injection Core 1 powered pumps. system. This SAMA was originally intended for the Cooling Westinghouse-CE System 80+, which has four trains of safety injection. However, the intent of this SAMA is to provide diversity within the high- and l Callaway Plant Unit 1 Environmental Report for License Renewal F-57

Attachment F Severe Accident Mitigation Alternatives Table 5-1. List of SAMA Candidates (Continued).

Callaway SAMA Focus of Number Potential Improvement Discussion SAMA Source 40 Provide capability for remote, manual operation of secondary side Improved chance of successful operation during station Core 1 pilot-operated relief valves in a station blackout. blackout events in which high area temperatures may be Cooling encountered (no ventilation to main steam areas).

41 Create a reactor coolant depressurization system. Allows low pressure emergency core cooling system Core 1 injection in the event of small LOCA and high-pressure Cooling safety injection failure.

42 Make procedure changes for reactor coolant system Allows low pressure emergency core cooling system Core 1 depressurization. injection in the event of small LOCA and high-pressure Cooling safety injection failure.

43 Add redundant DC control power for SW pumps. Increased availability of SW. Cooling 1 Water 44 Replace ECCS pump motors with air-cooled motors. Elimination of ECCS dependency on component cooling Cooling 1 system. Water 45 Enhance procedural guidance for use of cross-tied component Reduced frequency of loss of component cooling water Cooling 1 cooling or service water pumps. and service water. Water 46 Add a service water pump. Increased availability of cooling water. Cooling 1 Water 47 Enhance the screen wash system. Reduced potential for loss of SW due to clogging of Cooling 1 screens. Water 48 Cap downstream piping of normally closed component cooling water Reduced frequency of loss of component cooling water Cooling 1 drain and vent valves. initiating events, some of which can be attributed to Water catastrophic failure of one of the many single isolation valves.

49 Enhance loss of component cooling water (or loss of service water) Reduced potential for reactor coolant pump seal Cooling 1 procedures to facilitate stopping the reactor coolant pumps. damage due to pump bearing failure. Water 50 Enhance loss of component cooling water procedure to underscore Reduced probability of reactor coolant pump seal failure. Cooling 1 the desirability of cooling down the reactor coolant system prior to Water seal LOCA.

51 Additional training on loss of component cooling water. Improved success of operator actions after a loss of Cooling 1 component cooling water. Water 52 Provide hardware connections to allow another essential raw cooling Reduced effect of loss of component cooling water by Cooling 1 water system to cool charging pump seals. providing a means to maintain the charging pump seal Water injection following a loss of normal cooling water.

53 On loss of essential raw cooling water, proceduralize shedding Increased time before loss of component cooling water Cooling 1 component cooling water loads to extend the component cooling (and reactor coolant pump seal failure) during loss of Water water heat-up time. essential raw cooling water sequences.

54 Increase charging pump lube oil capacity. Increased time before charging pump failure due to lube Cooling 1 oil overheating in loss of cooling water sequences. Water Callaway Plant Unit 1 Environmental Report for License Renewal F-58

Attachment F Severe Accident Mitigation Alternatives Table 5-1. List of SAMA Candidates (Continued).

Callaway SAMA Focus of Number Potential Improvement Discussion SAMA Source 55 Install an independent reactor coolant pump seal injection system, Reduced frequency of core damage from loss of Cooling 1 with dedicated diesel. component cooling water, service water, or station Water blackout.

56 Install an independent reactor coolant pump seal injection system, Reduced frequency of core damage from loss of Cooling 1 without dedicated diesel. component cooling water or service water, but not a Water station blackout.

57 Use existing hydro test pump for reactor coolant pump seal injection. Reduced frequency of core damage from loss of Cooling 1 component cooling water or service water, but not a Water station blackout, unless an alternate power source is used.

58 Install improved reactor coolant pump seals. Reduced likelihood of reactor coolant pump seal LOCA. Cooling 1 Water 59 Install an additional component cooling water pump. Reduced likelihood of loss of component cooling water Cooling 1 leading to a reactor coolant pump seal LOCA. Water 60 Prevent makeup pump flow diversion through the relief valves. Reduced frequency of loss of reactor coolant pump seal Cooling 1 cooling if spurious high pressure injection relief valve Water opening creates a flow diversion large enough to prevent reactor coolant pump seal injection.

61 Change procedures to isolate reactor coolant pump seal return flow Reduced frequency of core damage due to loss of seal Cooling 1 on loss of component cooling water, and provide (or enhance) cooling. Water guidance on loss of injection during seal LOCA.

62 Implement procedures to stagger high pressure safety injection Extended high pressure injection prior to overheating Cooling 1 pump use after a loss of service water. following a loss of service water. Water 63 Use fire prevention system pumps as a backup seal injection and Reduced frequency of reactor coolant pump seal LOCA. Cooling 1 high pressure makeup source. Water 64 Implement procedure and hardware modifications to allow manual Improved ability to cool residual heat removal heat Cooling 1 alignment of the fire water system to the component cooling water exchangers. Water system, or install a component cooling water header cross-tie.

65 Install a digital feed water upgrade. Reduced chance of loss of main feed water following a Feedwater/ 1 plant trip. Condensate 66 Create ability for emergency connection of existing or new water Increased availability of feedwater. Feedwater/ 1 sources to feedwater and condensate systems. Condensate 67 Install an independent diesel for the condensate storage tank Extended inventory in CST during an SBO. Feedwater/ 1 makeup pumps. Condensate 68 Add a motor-driven feedwater pump. Increased availability of feedwater. Feedwater/ 1 Condensate 69 Install manual isolation valves around auxiliary feedwater turbine- Reduced dual turbine-driven pump maintenance Feedwater/ 1 driven steam admission valves. unavailability. Condensate Callaway Plant Unit 1 Environmental Report for License Renewal F-59

Attachment F Severe Accident Mitigation Alternatives Table 5-1. List of SAMA Candidates (Continued).

Callaway SAMA Focus of Number Potential Improvement Discussion SAMA Source 70 Install accumulators for turbine-driven auxiliary feedwater pump flow Eliminates the need for local manual action to align Feedwater/ 1 control valves. nitrogen bottles for control air following a loss of off-site Condensate power.

71 Install a new condensate storage tank (auxiliary feedwater storage Increased availability of the auxiliary feedwater system. Feedwater/ 1 tank). Condensate 72 Modify the turbine-driven auxiliary feedwater pump to be self-cooled. Improved success probability during a station blackout. Feedwater/ 1 Condensate 73 Proceduralize local manual operation of auxiliary feedwater system Extended auxiliary feedwater availability during a station Feedwater/ 1 when control power is lost. blackout. Also provides a success path should auxiliary Condensate feedwater control power be lost in non-station blackout sequences.

74 Provide hookup for portable generators to power the turbine-driven Extended auxiliary feedwater availability. Feedwater/ 1 auxiliary feedwater pump after station batteries are depleted. Condensate 75 Use fire water system as a backup for steam generator inventory. Increased availability of steam generator water supply. Feedwater/ 1 Condensate 76 Change failure position of condenser makeup valve if the condenser Allows greater inventory for the auxiliary feedwater Feedwater/ 1 makeup valve fails open on loss of air or power. pumps by preventing condensate storage tank flow Condensate diversion to the condenser.

77 Provide a passive, secondary-side heat-rejection loop consisting of a Reduced potential for core damage due to loss-of- Feedwater/ 1 condenser and heat sink. feedwater events. Condensate 78 Modify the startup feedwater pump so that it can be used as a Increased reliability of decay heat removal. Feedwater/ 1 backup to the emergency feedwater system, including during a Condensate station blackout scenario.

79 Replace existing pilot-operated relief valves with larger ones, such Increased probability of successful feed and bleed. Feedwater/ 1 that only one is required for successful feed and bleed. Condensate 80 Provide a redundant train or means of ventilation. Increased availability of components dependent on HVAC 1 room cooling.

81 Add a diesel building high temperature alarm or redundant louver Improved diagnosis of a loss of diesel building HVAC. HVAC 1 and thermostat.

82 Stage backup fans in switchgear rooms. Increased availability of ventilation in the event of a loss HVAC 1 of switchgear ventilation.

83 Add a switchgear room high temperature alarm. Improved diagnosis of a loss of switchgear HVAC. HVAC 1 84 Create ability to switch emergency feedwater room fan power supply Continued fan operation in a station blackout. HVAC 1 to station batteries in a station blackout.

85 Provide cross-unit connection of uninterruptible compressed air Increased ability to vent containment using the IA/Nitrogen 1 supply. hardened vent.

86 Modify procedure to provide ability to align diesel power to more air Increased availability of instrument air after a LOOP. IA/Nitrogen 1 compressors.

Callaway Plant Unit 1 Environmental Report for License Renewal F-60

Attachment F Severe Accident Mitigation Alternatives Table 5-1. List of SAMA Candidates (Continued).

Callaway SAMA Focus of Number Potential Improvement Discussion SAMA Source 87 Replace service and instrument air compressors with more reliable Elimination of instrument air system dependence on IA/Nitrogen 1 compressors which have self-contained air cooling by shaft driven service water cooling.

fans.

88 Install nitrogen bottles as backup gas supply for safety relief valves. Extended SRV operation time. IA/Nitrogen 1 89 Improve SRV and MSIV pneumatic components. Improved availability of SRVs and MSIVs. IA/Nitrogen 1 90 Create a reactor cavity flooding system. Enhanced debris cool ability, reduced core concrete Containment 1 interaction, and increased fission product scrubbing. Phenomena 91 Install a passive containment spray system. Improved containment spray capability. Containment 1 Phenomena 92 Use the fire water system as a backup source for the containment Improved containment spray capability. Containment 1 spray system. Phenomena 93 Install an unfiltered, hardened containment vent. Increased decay heat removal capability for non-ATWS Containment 1 events, without scrubbing released fission products. Phenomena 94 Install a filtered containment vent to remove decay heat. Option 1: Increased decay heat removal capability for non-ATWS Containment 1 Gravel Bed Filter; Option 2: Multiple Venturi Scrubber events, with scrubbing of released fission products. Phenomena 95 Enhance fire protection system and standby gas treatment system Improved fission product scrubbing in severe accidents. Containment 1 hardware and procedures. Phenomena 96 Provide post-accident containment inerting capability. Reduced likelihood of hydrogen and carbon monoxide Containment 1 gas combustion. Phenomena 97 Create a large concrete crucible with heat removal potential to Increased cooling and containment of molten core Containment 1 contain molten core debris. debris. Molten core debris escaping from the vessel is Phenomena contained within the crucible and a water cooling mechanism cools the molten core in the crucible, preventing melt-through of the base mat.

98 Create a core melt source reduction system. Increased cooling and containment of molten core Containment 1 debris. Refractory material would be placed underneath Phenomena the reactor vessel such that a molten core falling on the material would melt and combine with the material.

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

99 Strengthen primary/secondary containment (e.g., add ribbing to Reduced probability of containment over-pressurization. Containment 1 containment shell). Phenomena 100 Increase depth of the concrete base mat or use an alternate Reduced probability of base mat melt-through. Containment 1 concrete material to ensure melt-through does not occur. Phenomena 101 Provide a reactor vessel exterior cooling system. Increased potential to cool a molten core before it Containment 1 causes vessel failure, by submerging the lower head in Phenomena water.

Callaway Plant Unit 1 Environmental Report for License Renewal F-61

Attachment F Severe Accident Mitigation Alternatives Table 5-1. List of SAMA Candidates (Continued).

Callaway SAMA Focus of Number Potential Improvement Discussion SAMA Source 102 Construct a building to be connected to primary/secondary Reduced probability of containment over-pressurization. Containment 1 containment and maintained at a vacuum. Phenomena 103 Institute simulator training for severe accident scenarios. Improved arrest of core melt progress and prevention of Containment 1 containment failure. Phenomena 104 Improve leak detection procedures. Increased piping surveillance to identify leaks prior to Containment 1 complete failure. Improved leak detection would reduce Phenomena LOCA frequency.

105 Delay containment spray actuation after a large LOCA. Extended reactor water storage tank availability. Containment 1 Phenomena 106 Install automatic containment spray pump header throttle valves. Extended time over which water remains in the reactor Containment 1 water storage tank, when full containment spray flow is Phenomena not needed.

107 Install a redundant containment spray system. Increased containment heat removal ability. Containment 1 Phenomena 108 Install an independent power supply to the hydrogen control system Reduced hydrogen detonation potential. Containment 1 using either new batteries, a non-safety grade portable generator, Phenomena existing station batteries, or existing AC/DC independent power supplies, such as the security system diesel.

109 Install a passive hydrogen control system. Reduced hydrogen detonation potential. Containment 1 Phenomena 110 Erect a barrier that would provide enhanced protection of the Reduced probability of containment failure. Containment 1 containment walls (shell) from ejected core debris following a core Phenomena melt scenario at high pressure.

111 Install additional pressure or leak monitoring instruments for Reduced ISLOCA frequency. Containment 1 detection of ISLOCAs. Bypass 112 Add redundant and diverse limit switches to each containment Reduced frequency of containment isolation failure and Containment 1 isolation valve. ISLOCAs. Bypass 113 Increase leak testing of valves in ISLOCA paths. Reduced ISLOCA frequency. Containment 1 Bypass 114 Install self-actuating containment isolation valves. Reduced frequency of isolation failure. Containment 1 Bypass 115 Locate residual heat removal (RHR) inside containment Reduced frequency of ISLOCA outside containment. Containment 1 Bypass 116 Ensure ISLOCA releases are scrubbed. One method is to plug Scrubbed ISLOCA releases. Containment 1 drains in potential break areas so that break point will be covered Bypass with water.

Callaway Plant Unit 1 Environmental Report for License Renewal F-62

Attachment F Severe Accident Mitigation Alternatives Table 5-1. List of SAMA Candidates (Continued).

Callaway SAMA Focus of Number Potential Improvement Discussion SAMA Source 117 Revise EOPs to improve ISLOCA identification. Increased likelihood that LOCAs outside containment Containment 1 are identified as such. A plant had a scenario in which Bypass an RHR ISLOCA could direct initial leakage back to the pressurizer relief tank, giving indication that the LOCA was inside containment.

118 Improve operator training on ISLOCA coping. Decreased ISLOCA consequences. Containment 1 Bypass 119 Institute a maintenance practice to perform a 100% inspection of Reduced frequency of steam generator tube ruptures. Containment 1 steam generator tubes during each refueling outage. Bypass 120 Replace steam generators with a new design. Reduced frequency of steam generator tube ruptures. Containment 1 Bypass 121 Increase the pressure capacity of the secondary side so that a steam Eliminates release pathway to the environment following Containment 1 generator tube rupture would not cause the relief valves to lift. a steam generator tube rupture. Bypass 122 Install a redundant spray system to depressurize the primary system Enhanced depressurization capabilities during steam Containment 1 during a steam generator tube rupture generator tube rupture. Bypass 123 Proceduralize use of pressurizer vent valves during steam generator Backup method to using pressurizer sprays to reduce Containment 1 tube rupture sequences. primary system pressure following a steam generator Bypass tube rupture.

124 Provide improved instrumentation to detect steam generator tube Improved mitigation of steam generator tube ruptures. Containment 1 ruptures, such as Nitrogen-16 monitors). Bypass 125 Route the discharge from the main steam safety valves through a Reduced consequences of a steam generator tube Containment 1 structure where a water spray would condense the steam and rupture. Bypass remove most of the fission products.

126 Install a highly reliable (closed loop) steam generator shell-side heat Reduced consequences of a steam generator tube Containment 1 removal system that relies on natural circulation and stored water rupture. Bypass sources 127 Revise emergency operating procedures to direct isolation of a Reduced consequences of a steam generator tube Containment 1 faulted steam generator. rupture. Bypass 128 Direct steam generator flooding after a steam generator tube Improved scrubbing of steam generator tube rupture Containment 1 rupture, prior to core damage. releases. Bypass 129 Vent main steam safety valves in containment. Reduced consequences of a steam generator tube Containment 1 rupture. Bypass 130 Add an independent boron injection system. Improved availability of boron injection during ATWS. ATWS 1 131 Add a system of relief valves to prevent equipment damage from Improved equipment availability after an ATWS. ATWS 1 pressure spikes during an ATWS.

132 Provide an additional control system for rod insertion (e.g., AMSAC). Improved redundancy and reduced ATWS frequency. ATWS 1 133 Install an ATWS sized filtered containment vent to remove decay Increased ability to remove reactor heat from ATWS ATWS 1 heat. events.

Callaway Plant Unit 1 Environmental Report for License Renewal F-63

Attachment F Severe Accident Mitigation Alternatives Table 5-1. List of SAMA Candidates (Continued).

Callaway SAMA Focus of Number Potential Improvement Discussion SAMA Source 134 Revise procedure to bypass MSIV isolation in turbine trip ATWS Affords operators more time to perform actions. ATWS 1 scenarios. Discharge of a substantial fraction of steam to the main condenser (i.e., as opposed to into the primary containment) affords the operator more time to perform actions (e.g., SLC injection, lower water level, depressurize RPV) than if the main condenser was unavailable, resulting in lower human error probabilities.

135 Revise procedure to allow override of low pressure core injection Allows immediate control of low pressure core injection. ATWS 1 during an ATWS event. On failure of high pressure core injection and condensate, some plants direct reactor depressurization followed by five minutes of automatic low pressure core injection.

136 Install motor generator set trip breakers in control room. Reduced frequency of core damage due to an ATWS. ATWS 1 137 Provide capability to remove power from the bus powering the Decreased time required to insert control rods if the ATWS 1 control rods. reactor trip breakers fail (during a loss of feedwater ATWS which has rapid pressure excursion).

138 Improve inspection of rubber expansion joints on main condenser. Reduced frequency of internal flooding due to failure of Internal 1 circulating water system expansion joints. Flooding 139 Modify swing direction of doors separating turbine building basement Prevents flood propagation. Internal 1 from areas containing safeguards equipment. Flooding 140 Increase seismic ruggedness of plant components. Increased availability of necessary plant equipment Seismic Risk 1 during and after seismic events.

141 Provide additional restraints for CO2 tanks. Increased availability of fire protection given a seismic Seismic Risk 1 event.

142 Replace mercury switches in fire protection system. Decreased probability of spurious fire suppression Fire Risk 1 system actuation.

143 Upgrade fire compartment barriers. Decreased consequences of a fire. Fire Risk 1 144 Install additional transfer and isolation switches. Reduced number of spurious actuations during a fire. Fire Risk 1 145 Enhance fire brigade awareness. Decreased consequences of a fire. Fire Risk 1 146 Enhance control of combustibles and ignition sources. Decreased fire frequency and consequences. Fire Risk 1 147 Install digital large break LOCA protection system. Reduced probability of a large break LOCA (a leak Other 1 before break).

148 Enhance procedures to mitigate large break LOCA. Reduced consequences of a large break LOCA. Other 1 149 Install computer aided instrumentation system to assist the operator Improved prevention of core melt sequences by making Other 1 in assessing post-accident plant status. operator actions more reliable.

150 Improve maintenance procedures. Improved prevention of core melt sequences by Other 1 increasing reliability of important equipment.

151 Increase training and operating experience feedback to improve Improved likelihood of success of operator actions taken Other 1 operator response. in response to abnormal conditions.

Callaway Plant Unit 1 Environmental Report for License Renewal F-64

Attachment F Severe Accident Mitigation Alternatives Table 5-1. List of SAMA Candidates (Continued).

Callaway SAMA Focus of Number Potential Improvement Discussion SAMA Source 152 Develop procedures for transportation and nearby facility accidents. Reduced consequences of transportation and nearby Other 1 facility accidents.

153 Install secondary side guard pipes up to the main steam isolation Prevents secondary side depressurization should a Other 1 valves. steam line break occur upstream of the main steam isolation valves. Also guards against or prevents consequential multiple steam generator tube ruptures following a main steam line break event.

154 Mount or anchor the MCCs to the respective building walls. Reduces failure probability of MCCs during an IPEEE - B earthquake Seismic 155 Install shear pins (or strength bolts) in the AFW pumps. Takes up the shear load on the pump and/or driver IPEEE - B during an earthquake. Seismic 156 Mount all fire extinguishers within their UL Standard required drop Reduces the potential for the fire extinguishers to fall IPEEE - B height and remove hand-held fire extinguishers from Containment during an earthquake and potentially fracturing upon Seismic during normal operation. impact with the floor or another object.

157 Identify and remove unsecured equipment near areas that contain Ensures direct access to areas such as Load Shedding IPEEE - B relays that actuate, so area is kept clear. and Emergency Load Sequencing (LSELS) and Seismic Engineered Safety Feature Actuation System (ESFAS) cabinets. Unsecured equipment (e.g.,

carts, filing cabinets, and test equipment) in these areas could result 158 Properly position chain hoists that facilitate maintenance on pumps Improper positioning of hoists reduces the availability IPEEE - B within pump rooms and institute a training program to ensure that the due to moving during an earthquake and having Seismic hoists are properly positioned when not in use. chainfalls impacting pump oil bubblers or other soft targets resulting in failure of the pumps.

159 Secure floor grating to prevent damage to sensing lines due to Prevent sensing lines that pass through the grating from IPEEE - B differential building motion. being damaged. Seismic 160 Modifications to lessen impact of internal flooding path through Lower impact of flood that propagates through the Internal D Control Building dumbwaiter. dumbwaiter Flooding 161 Improvements to PORV performance that will lower the probability of Decrease in risk due to PORV failing to open. Core E failure to open. Cooling 162 Install a large volume EDG fuel oil tank at an elevation greater than Allows transfer of EDF fuel oil to the EDG day tanks on AC/DC C the EDG fuel oil day tanks. failure of the fuel oil transfer pumps.

163 Improve feedwater check valve reliability to reduce probability of Lower risk due to failures in which feedwater check Cooling E failure to open. valves fail to open and allow feeding of the steam Water generators.

164 Provide the capability to power the normal service water pumps from Provide backup to ESW in conditions with power only Cooling D AEPS. available from AEPS. Water Callaway Plant Unit 1 Environmental Report for License Renewal F-65

Attachment F Severe Accident Mitigation Alternatives Table 5-1. List of SAMA Candidates (Continued).

Callaway SAMA Focus of Number Potential Improvement Discussion SAMA Source 165 Purchase or manufacture a "gagging device" that could be used to Reduce the amount of radioactive material release to SGTR C close a stuck open steam generator relief valve for a SGTR event the atmosphere in a SGTR event with core damage.

prior to core damage.

166 Installation of high temperature qualified RCP seal O-rings. Lower potential for RCP seal leakage. RCP Seal A LOCA 167 Addition of procedural guidance to re-establish normal service water Provide back-up pumps for UHS cooling. Cooling A should essential service water fail. Water 168 Addition of procedural guidance for running charging and safety Allow use of pumps following loss of component cooling Cooling A injection pumps without component cooling water water. Water 169 Addition of procedural guidance to verify RHR pump room cooling at Verifying that support system for RHR pumps is in HVAC A switchover to ECCS recirculation phase. service to allow continued operation of RHR pumps.

170 Modifications to add controls in the main control room to allow Faster ability to provide power to the plant electrical AC Power C remote operation of nearby diesel generator farm and busses from the offsite diesel generator farm.

alignment/connection to the plant vital electrical busses.

171 Increase the size of the RWST or otherwise improve the availability Ensure a supply of makeup water is available from the Core E of the RWST RWST. Cooling Note 1: The source references are:

1 NEI 05-01 (Reference 19)

A IPE (Reference 28)

B IPEEE (Reference 29)

C Recent industry SAMA submittals (Wolf Creek, South Texas, Diablo Canyon, Seabrook)

D Expert panel convened to review SAMA analysis E PRA importance list review Callaway Plant Unit 1 Environmental Report for License Renewal F-66

Attachment F Severe Accident Mitigation Alternatives 6.0 PHASE I ANALYSIS A preliminary screening of the complete list of SAMA candidates was performed to limit the number of SAMAs for which detailed analysis in Phase II was necessary. The screening criteria used in the Phase I analysis are described below.

• Screening Criterion A - Not Applicable: If a SAMA candidate did not apply to the Callaway Unit 1 plant design, it was not retained.

• Screening Criterion B - Already Implemented or Intent Met: If a SAMA candidate had already been implemented at the Callaway Plant or its intended benefit already achieved by other means, it was not retained.

• Screening Criterion C - Combined: If a SAMA candidate was similar in nature and could be combined with another SAMA candidate to develop a more comprehensive or plant-specific SAMA candidate, only the combined SAMA candidate was retained.

• Screening Criterion D - Excessive Implementation Cost: If a SAMA required extensive changes that will obviously exceed the maximum benefit (Section 4.5), even without an implementation cost estimate, it was not retained.

• Screening Criterion E - Very Low Benefit: If a SAMA from an industry document was related to a non-risk significant system for which change in reliability is known to have negligible impact on the risk profile, it was not retained. (No SAMAs were screened using this criterion.)

Table 6-1 presents the list of Phase I SAMA candidates and provides the disposition of each candidate along with the applicable screening criterion associated with each candidate. Those candidates that have not been screened by application of these criteria are evaluated further in the Phase II analysis (Section 7). It can be seen from this table that 107 SAMAs were screened from the analysis during Phase 1 and that 64 SAMAs passed into the next phase of the analysis.

Callaway Plant Unit 1 Environmental Report for License Renewal F-67

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 12 Create AC power cross-tie Increased availability of on-site AC power. Yes A - Not Applicable Callaway is a single unit site.

capability with other unit (multi-unit site) 17 Create a cross-tie for diesel fuel oil Increased diesel generator availability. Yes A - Not Applicable Callaway is a single unit site.

(multi-unit site).

27 Revise procedure to allow Extended HPCI and RCIC operation. Yes A - Not Applicable BWR item.

operators to inhibit automatic vessel depressurization in non-ATWS scenarios.

34 Provide an in-containment reactor Continuous source of water to the safety Yes A - Not Applicable Not applicable for existing water storage tank. injection pumps during a LOCA event, since designs. Insufficient room water released from a breach of the primary inside primary containment.

system collects in the in-containment reactor water storage tank, and thereby eliminates the need to realign the safety injection pumps for long-term post-LOCA recirculation.

35 Throttle low pressure injection Extended reactor water storage tank Yes A - Not Applicable Per the Callaway safety pumps earlier in medium or large- capacity. analysis, this is an break LOCAs to maintain reactor undesirable action. The water storage tank inventory. Callaway safety analysis and design calls for injection of the RWST to inside the containment as soon as possible.

38 Change the in-containment reactor Reduced common mode failure of injection Yes A - Not Applicable Callaway does not have an in-water storage tank suction from paths. containment RWST with this four check valves to two check and valve arrangement.

two air-operated valves.

47 Enhance the screen wash system. Reduced potential for loss of SW due to Yes A - Not Applicable Plant uses Ultimate Heat Sink clogging of screens. pond for cooling. UHS sized for 30 days without make-up.

River intake is only used for make-up to the UHS.

52 Provide hardware connections to Reduced effect of loss of component cooling Yes A - Not Applicable Charging pump seals do not allow another essential raw cooling water by providing a means to maintain the require external cooling, they water system to cool charging charging pump seal injection following a loss are cooled by the process pump seals. of normal cooling water. fluid.

Callaway Plant Unit 1 Environmental Report for License Renewal F-68

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 57 Use existing hydro test pump for Reduced frequency of core damage from Yes A - Not Applicable Callaway does not have a reactor coolant pump seal injection. loss of component cooling water or service permanently installed hydro water, but not a station blackout, unless an test pump. Timing alternate power source is used. considerations prevent credit for hookup of temporary pump.

63 Use fire prevention system pumps Reduced frequency of reactor coolant pump Yes A - Not Applicable Existing fire protection system as a backup seal injection and high seal LOCA. pumps do not have sufficient pressure makeup source. discharge head to use as high pressure makeup source.

69 Install manual isolation valves Reduced dual turbine-driven pump Yes A - Not Applicable Callaway does not have dual around auxiliary feedwater turbine- maintenance unavailability. turbine AFW pump.

driven steam admission valves.

85 Provide cross-unit connection of Increased ability to vent containment using Yes A - Not Applicable N/A, single unit.

uninterruptible compressed air the hardened vent.

supply.

95 Enhance fire protection system and Improved fission product scrubbing in severe Yes A - Not Applicable Standby gas treatment system standby gas treatment system accidents. is BWR item.

hardware and procedures.

105 Delay containment spray actuation Extended reactor water storage tank Yes A - Not Applicable Per the Callaway safety after a large LOCA. availability. analysis, this is an undesirable action. The Callaway safety analysis and design calls for injection of the RWST to inside the containment as soon as possible.

106 Install automatic containment spray Extended time over which water remains in Yes A - Not Applicable Per the Callaway safety pump header throttle valves. the reactor water storage tank, when full analysis, this is an containment spray flow is not needed. undesirable action. The Callaway safety analysis and design calls for injection of the RWST to inside the containment as soon as possible.

Callaway Plant Unit 1 Environmental Report for License Renewal F-69

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 134 Revise procedure to bypass MSIV Affords operators more time to perform Yes A - Not Applicable Specific to BWRs.

isolation in turbine trip ATWS actions. Discharge of a substantial fraction of scenarios. steam to the main condenser (i.e., as opposed to into the primary containment) affords the operator more time to perform actions (e.g., SLC injection, lower water level, depressurize RPV) than if the main condenser was unavailable, resulting in lower human error probabilities.

135 Revise procedure to allow override Allows immediate control of low pressure Yes A - Not Applicable Based on description, this is a of low pressure core injection core injection. On failure of high pressure BWR item.

during an ATWS event. core injection and condensate, some plants direct reactor depressurization followed by five minutes of automatic low pressure core injection.

138 Improve inspection of rubber Reduced frequency of internal flooding due to Yes A - Not Applicable No risk significant flooding expansion joints on main failure of circulating water system expansion sources identified in the condenser. joints. turbine building.

139 Modify swing direction of doors Prevents flood propagation. Yes A - Not Applicable Flooding analysis did not separating turbine building indicate any flooding issues basement from areas containing related to the direction of door safeguards equipment. swing.

142 Replace mercury switches in fire Decreased probability of spurious fire Yes A - Not Applicable No mercury switches in the protection system. suppression system actuation. fire protection system.

143 Upgrade fire compartment barriers. Decreased consequences of a fire. Yes A - Not Applicable Fire analysis did not identify any issues related to fire barriers. NFPA 805 Fire Protection Program is in progress, any issues identified by that project will be handled by the NFPA 805 program.

152 Develop procedures for Reduced consequences of transportation and Yes A - Not Applicable IPEEE determined that there transportation and nearby facility nearby facility accidents. are no transportation routes or accidents. nearby facilities that could cause concern.

Callaway Plant Unit 1 Environmental Report for License Renewal F-70

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 165 Purchase or manufacture a Reduce the amount of radioactive material Yes A - Not Applicable Callaway does not have the "gagging device" that could be release to the atmosphere in a SGTR event ability to isolate the steam used to close a stuck open steam with core damage. generator from the RCS loop.

generator relief valve for a SGTR The amount of force required event prior to core damage. to close a stuck open atmospheric steam dump valve would likely not be successful and would result in further damage to the valve.

3 Add additional battery charger or Improved availability of DC power system. Yes B - Intent Met Current configuration is two portable, diesel-driven battery spare battery chargers for the charger to existing DC system. instrument buses. The spare can carry one bus. One feeds A/B, the other feeds C/D trains. Also Emergency Coordinator Supplemental Guidelines, Attachment N, "Temporary Power to NK Swing Charger 4 Improve DC bus load shedding. Extended DC power availability during an Yes B - Intent Met DC load shedding is SBO. conducted.

6 Provide additional DC power to the Increased availability of the 120 V vital AC Yes B - Intent Met Procedures in place to provide 120/240V vital AC system. bus. temporary power to DC Chargers which can power vital AC system.

7 Add an automatic feature to Increased availability of the 120 V vital AC Yes B - Intent Met On loss of DC or inverter, the transfer the 120V vital AC bus from bus. UPS static switch normal to standby power. automatically transfers to AC power through a constant voltage transformer. An additional backup AC source is available, but must be closed manually.

8 Increase training on response to Improved chances of successful response to Yes B - Intent Met Typical response training in loss of two 120V AC buses which loss of two 120V AC buses. place.

causes inadvertent actuation signals.

9 Provide an additional diesel Increased availability of on-site emergency Yes B - Intent Met Alternate Emergency Power generator. AC power. System installed.

Callaway Plant Unit 1 Environmental Report for License Renewal F-71

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 10 Revise procedure to allow bypass Extended diesel generator operation. Yes B - Intent Met Bypass of non-vital diesel of diesel generator trips. generator trips were in original design for Callaway.

13 Install an additional, buried off-site Reduced probability of loss of off-site power. Yes B - Intent Met AEPS installed with buried power source. power lines.

14 Install a gas turbine generator. Increased availability of on-site AC power. Yes B - Intent Met Alternate Emergency Power System installed.

16 Improve uninterruptible power Increased availability of power supplies Yes B - Intent Met Replaced to add static switch supplies. supporting front-line equipment. and upgrade to newer design.

18 Develop procedures for Increased diesel generator availability. Yes B - Intent Met EOP Addenda direct ordering replenishing diesel fuel oil. fuel oil.

19 Use fire water system as a backup Increased diesel generator availability. Yes B - Intent Met Procedures exist for cooling source for diesel cooling. EDG with fire water.

20 Add a new backup source of diesel Increased diesel generator availability. Yes B - Intent Met Procedure exists for backup cooling. diesel cooling.

21 Develop procedures to repair or Increased probability of recovery from failure Yes B - Intent Met Spares exist and procedures replace failed 4 KV breakers. of breakers that transfer 4.16 kV non- exist.

emergency buses from unit station service transformers.

22 In training, emphasize steps in Reduced human error probability during off- Yes B - Intent Met Recovery stressed in training.

recovery of off-site power after an site power recovery.

SBO.

23 Develop a severe weather Improved off-site power recovery following Yes B - Intent Met Severe weather condition conditions procedure. external weather-related events. procedure in place.

30 Improve ECCS suction strainers. Enhanced reliability of ECCS suction. Yes B - Intent Met Callaway has implemented a containment sump modification that now uses state-of-the-art strainers to address the industrys concerns on blockage from debris. This modification occurred over two outages in 2007 and 2008.

31 Add the ability to manually align Enhanced reliability of ECCS suction. Yes B - Intent Met Current alignment capabilities emergency core cooling system are half and half recirculation. (manual/automatic).

Callaway Plant Unit 1 Environmental Report for License Renewal F-72

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 32 Add the ability to automatically Enhanced reliability of ECCS suction. Yes B - Intent Met Current alignment capabilities align emergency core cooling are half and half system to recirculation mode upon (manual/automatic).

refueling water storage tank depletion.

33 Provide hardware and procedure to Extended reactor water storage tank capacity Yes B - Intent Met Addressed in SAMGs and the refill the reactor water storage tank in the event of a steam generator tube EC Supplemental Guideline.

once it reaches a specified low rupture (or other LOCAs challenging RWST level. capacity).

36 Emphasize timely recirculation Reduced human error probability associated Yes B - Intent Met Current alignment capabilities alignment in operator training. with recirculation failure. are half and half (manual/automatic). Swap to recirculation is stressed in operator training.

37 Upgrade the chemical and volume For a plant like the Westinghouse AP600, Yes B - Intent Met CVCS system is capable of control system to mitigate small where the chemical and volume control mitigating small LOCA.

LOCAs. system cannot mitigate a small LOCA, an upgrade would decrease the frequency of core damage.

40 Provide capability for remote, Improved chance of successful operation Yes B - Intent Met Remote Operation of manual operation of secondary side during station blackout events in which high Atmospheric Steam Dumps pilot-operated relief valves in a area temperatures may be encountered (no (ASDs) is possible.

station blackout. ventilation to main stream areas). Equipment Operators trained and Operator Aid posted.

42 Make procedure changes for Allows low pressure emergency core cooling Yes B - Intent Met Multiple depressurization reactor coolant system system injection in the event of small LOCA methods are in place.

depressurization. and high-pressure safety injection failure.

44 Replace ECCS pump motors with Elimination of ECCS dependency on Yes B - Intent Met Current ECCS pump motors air-cooled motors. component cooling system. are air-cooled. Additionally the plant OTN procedures allow for alternate trains to supply cooling.

45 Enhance procedural guidance for Reduced frequency of loss of component Yes B - Intent Met Can use service water as use of cross-tied component cooling water and service water. backup to ESW.

cooling or service water pumps.

48 Cap downstream piping of normally Reduced frequency of loss of component Yes B - Intent Met Vents & drains capped.

closed component cooling water cooling water initiating events, some of which drain and vent valves. can be attributed to catastrophic failure of one of the many single isolation valves.

Callaway Plant Unit 1 Environmental Report for License Renewal F-73

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 49 Enhance loss of component cooling Reduced potential for reactor coolant pump Yes B - Intent Met CCW is cooled by ESW.

water (or loss of service water) seal damage due to pump bearing failure. Currently authorized to run 10 procedures to facilitate stopping the minutes.

reactor coolant pumps.

50 Enhance loss of component cooling Reduced probability of reactor coolant pump Yes B - Intent Met Procedures include direction water procedure to underscore the seal failure. to cool down to minimize desirability of cooling down the impact of RCP seal LOCA.

reactor coolant system prior to seal LOCA.

51 Additional training on loss of Improved success of operator actions after a Yes B - Intent Met Training is conducted for Loss component cooling water. loss of component cooling water. of CCW.

53 On loss of essential raw cooling Increased time before loss of component Yes B - Intent Met Most non-safety loads have water, proceduralize shedding cooling water (and reactor coolant pump seal been removed from the component cooling water loads to failure) during loss of essential raw cooling system. Non-safety loop is extend the component cooling water sequences. automatically isolated on water heat-up time. safety injection signal.

60 Prevent makeup pump flow Reduced frequency of loss of reactor coolant Yes B - Intent Met Current configuration does not diversion through the relief valves. pump seal cooling if spurious high pressure have a relief valve.

injection relief valve opening creates a flow diversion large enough to prevent reactor coolant pump seal injection.

61 Change procedures to isolate Reduced frequency of core damage due to Yes B - Intent Met Procedure exist reactor coolant pump seal return loss of seal cooling.

flow on loss of component cooling water, and provide (or enhance) guidance on loss of injection during seal LOCA.

62 Implement procedures to stagger Extended high pressure injection prior to Yes B - Intent Met Procedure currently in place high pressure safety injection pump overheating following a loss of service water. to stagger use of HPSI.

use after a loss of service water.

66 Create ability for emergency Increased availability of feedwater. Yes B - Intent Met Procedures exist.

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

67 Install an independent diesel for the Extended inventory in CST during an SBO. Yes B - Intent Met Procedures do exist for make-condensate storage tank makeup up to CST from fire water and pumps. for supplying fire water directly to the TDAFW pump.

68 Add a motor-driven feedwater Increased availability of feedwater. Yes B - Intent Met Non-Safety Auxiliary pump. Feedwater Pump installed.

Callaway Plant Unit 1 Environmental Report for License Renewal F-74

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 70 Install accumulators for turbine- Eliminates the need for local manual action to Yes B - Intent Met Currently have nitrogen driven auxiliary feedwater pump align nitrogen bottles for control air following accumulators.

flow control valves. a loss of off-site power.

72 Modify the turbine-driven auxiliary Improved success probability during a station Yes B - Intent Met Turbine-driven auxiliary feedwater pump to be self-cooled. blackout. feedwater pump is self-cooled.

73 Proceduralize local manual Extended auxiliary feedwater availability Yes B - Intent Met Procedures exist.

operation of auxiliary feedwater during a station blackout. Also provides a system when control power is lost. success path should auxiliary feedwater control power be lost in non-station blackout sequences.

74 Provide hookup for portable Extended auxiliary feedwater availability. Yes B - Intent Met Procedures exist, hardware generators to power the turbine- on site.

driven auxiliary feedwater pump after station batteries are depleted.

75 Use fire water system as a backup Increased availability of steam generator Yes B - Intent Met Equipment staged at CST for for steam generator inventory. water supply. makeup.

See operator aids.

Procedural guidance exists.

76 Change failure position of Allows greater inventory for the auxiliary Yes B - Intent Met Valve currently fails closed.

condenser makeup valve if the feedwater pumps by preventing condensate condenser makeup valve fails open storage tank flow diversion to the condenser.

on loss of air or power.

78 Modify the startup feedwater pump Increased reliability of decay heat removal. Yes B - Intent Met Non-Safety Auxiliary so that it can be used as a backup Feedwater Pump gets power to the emergency feedwater from Alternate Emergency system, including during a station Power System.

blackout scenario.

81 Add a diesel building high Improved diagnosis of a loss of diesel Yes B - Intent Met Computer points for temperature alarm or redundant building HVAC. monitoring diesel room louver and thermostat. temperatures.

82 Stage backup fans in switchgear Increased availability of ventilation in the Yes B - Intent Met Procedures include rooms. event of a loss of switchgear ventilation. instructions for opening doors to provide alternate cooling capability.

83 Add a switchgear room high Improved diagnosis of a loss of switchgear Yes B - Intent Met Plant Process Computer has temperature alarm. HVAC. alarming computer points for switchgear room temperature.

Callaway Plant Unit 1 Environmental Report for License Renewal F-75

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 84 Create ability to switch emergency Continued fan operation in a station blackout. Yes B - Intent Met Procedure currently in place feedwater room fan power supply to switch fan power supply.

to station batteries in a station blackout.

86 Modify procedure to provide ability Increased availability of instrument air after a Yes B - Intent Met Currently have 3 air to align diesel power to more air LOOP. compressors (service air).

compressors. A/B compressors are powered off the emergency buses (cooled from essential service lines). Compressors are initially load shed, but procedure direct operators to override and place compressor in service.

88 Install nitrogen bottles as backup Extended SRV operation time. Yes B - Intent Met Current configuration includes gas supply for safety relief valves. nitrogen bottles as backup gas supply.

89 Improve SRV and MSIV pneumatic Improved availability of SRVs and MSIVs. Yes B - Intent Met MSIV actuators changed to components. process fluid actuated.

Modification installed to relocate Atmospheric Steam Dump valve controllers.

90 Create a reactor cavity flooding Enhanced debris cool ability, reduced core Yes B - Intent Met Procedures exist system. concrete interaction, and increased fission product scrubbing.

92 Use the fire water system as a Improved containment spray capability. Yes B - Intent Met Procedures exist backup source for the containment spray system.

101 Provide a reactor vessel exterior Increased potential to cool a molten core Yes B - Intent Met Procedures exist.

cooling system. before it causes vessel failure, by submerging the lower head in water.

103 Institute simulator training for Improved arrest of core melt progress and Yes B - Intent Met Operators are trained on the severe accident scenarios. prevention of containment failure. SAMG that the operators must implement.

117 Revise EOPs to improve ISLOCA Increased likelihood that LOCAs outside Yes B - Intent Met Current EOPs address identification. containment are identified as such. A plant ISLOCA identification.

had a scenario in which an RHR ISLOCA could direct initial leakage back to the pressurizer relief tank, giving indication that the LOCA was inside containment.

Callaway Plant Unit 1 Environmental Report for License Renewal F-76

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 118 Improve operator training on Decreased ISLOCA consequences. Yes B - Intent Met Current procedure training ISLOCA coping. addresses ISLOCA identification.

120 Replace steam generators with a Reduced frequency of steam generator tube Yes B - Intent Met Replaced during the fall of new design. ruptures. 2005 (newer design) which consist of 72,000 sq. ft. per generator.

123 Proceduralize use of pressurizer Backup method to using pressurizer sprays Yes B - Intent Met Procedure currently in place.

vent valves during steam generator to reduce primary system pressure following tube rupture sequences. a steam generator tube rupture.

124 Provide improved instrumentation Improved mitigation of steam generator tube Yes B - Intent Met Modification installed to to detect steam generator tube ruptures. improve operation of N16 ruptures, such as Nitrogen-16 detectors.

monitors).

127 Revise emergency operating Reduced consequences of a steam Yes B - Intent Met EOP currently in place.

procedures to direct isolation of a generator tube rupture.

faulted steam generator.

128 Direct steam generator flooding Improved scrubbing of steam generator tube Yes B - Intent Met Procedures direct that steam after a steam generator tube rupture releases. generator level be maintained rupture, prior to core damage. above the tubes.

132 Provide an additional control Improved redundancy and reduced ATWS Yes B - Intent Met Currently have AMSAC.

system for rod insertion (e.g., frequency.

AMSAC).

137 Provide capability to remove power Decreased time required to insert control Yes B - Intent Met Response procedure in place.

from the bus powering the control rods if the reactor trip breakers fail (during a rods. loss of feedwater ATWS which has rapid pressure excursion).

144 Install additional transfer and Reduced number of spurious actuations Yes B - Intent Met Items are identified and are isolation switches. during a fire. being implemented as part of the 805 process.

Examples include fuse and alternate feed line modifications to prevent the loss of the 4160 V buses.

145 Enhance fire brigade awareness. Decreased consequences of a fire. Yes B - Intent Met Most recent inspections and evaluations did not identify any weaknesses in this area.

Callaway Plant Unit 1 Environmental Report for License Renewal F-77

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 146 Enhance control of combustibles Decreased fire frequency and consequences. Yes B - Intent Met Procedure in place. NFPA-and ignition sources. 805 project will evaluate the needs for any additional controls.

148 Enhance procedures to mitigate Reduced consequences of a large break Yes B - Intent Met Existing procedures meet large break LOCA. LOCA. current guidelines issued by the Owner's Group.

149 Install computer aided Improved prevention of core melt sequences Yes B - Intent Met Currently have SPDS in place.

instrumentation system to assist by making operator actions more reliable.

the operator in assessing post-accident plant status.

150 Improve maintenance procedures. Improved prevention of core melt sequences Yes B - Intent Met Current procedures are in line by increasing reliability of important with industry guidelines and equipment. practices.

151 Increase training and operating Improved likelihood of success of operator Yes B - Intent Met Current training program experience feedback to improve actions taken in response to abnormal meets industry standards and operator response. conditions. practices.

154 Mount or anchor the MCCs to the Reduces failure probability of MCCs during Yes B - Intent Met Identified in the IPEEE and respective building walls. an earthquake successfully implemented.

155 Install shear pins (or strength bolts) Takes up the shear load on the pump and/or Yes B - Intent Met Identified in the IPEEE and in the AFW pumps. driver during an earthquake. successfully implemented.

156 Mount all fire extinguishers within Reduces the potential for the fire Yes B - Intent Met Identified in the IPEEE and their UL Standard required drop extinguishers to fall during an earthquake successfully implemented.

height and remove hand-held fire and potentially fracturing upon impact with extinguishers from Containment the floor or another object.

during normal operation.

157 Identify and remove unsecured Ensures direct access to areas such as Load Yes B - Intent Met Identified in the IPEEE and equipment near areas that contain Shedding and Emergency Load Sequencing successfully implemented.

relays that actuate, so area is kept (LSELS) and Engineered Safety Feature clear. Actuation System (ESFAS) cabinets. Unsecured equipment (e.g., carts, filing cabinets, and test equipment) in these areas could result 158 Properly position chain hoists that Improper positioning of hoists reduces the Yes B - Intent Met Identified in the IPEEE and facilitate maintenance on pumps availability due to moving during an successfully implemented.

within pump rooms and institute a earthquake and having chainfalls impacting training program to ensure that the pump oil bubblers or other soft targets hoists are properly positioned when resulting in failure of the pumps.

not in use.

Callaway Plant Unit 1 Environmental Report for License Renewal F-78

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 159 Secure floor grating to prevent Prevent sensing lines that pass through the Yes B - Intent Met Identified in the IPEEE and damage to sensing lines due to grating from being damaged. successfully implemented.

differential building motion.

166 Installation of high temperature Lower potential for RCP seal leakage. Yes B - Intent Met High temperature O-Rings qualified RCP seal O-rings. installed.

167 Addition of procedural guidance to Provide back-up pumps for UHS cooling. Yes B - Intent Met Procedures in place.

re-establish normal service water should essential service water fail.

168 Addition of procedural guidance for Allow use of pumps following loss of Yes B - Intent Met Procedures in place.

running charging and safety component cooling water.

injection pumps without component cooling water 169 Addition of procedural guidance to Verifying that support system for RHR pumps Yes B - Intent Met Procedures in place.

verify RHR pump room cooling at is in service to allow continued operation of switchover to ECCS recirculation RHR pumps.

phase.

170 Modifications to add controls in the Faster ability to provide power to the plant Yes B - Intent Met AEPS diesel generators main control room to allow remote electrical busses from the offsite diesel automatically start upon loss operation of nearby diesel generator farm. of offsite power to the local generator farm and electrical co-op distribution alignment/connection to the plant system. The controls for the vital electrical busses. breakers to connect to the Callaway distribution system are in the main control room.

140 Increase seismic ruggedness of Increased availability of necessary plant Yes C - Combined Individual seismic issues plant components. equipment during and after seismic events. identified in the IPEEE are included as SAMA items 154, 155, 156, 157, 158, and 159.

141 Provide additional restraints for Increased availability of fire protection given Yes C - Combined Individual seismic issues CO2 tanks. a seismic event. identified in the IPEEE are included as SAMA items 154, 155, 156, 157, 158, and 159.

1 Provide additional DC battery Extended DC power availability during an No Original battery capacity is 4 capacity. SBO. hrs. No additional battery capacity has been added.

Evaluate in Phase II.

2 Replace lead-acid batteries with Extended DC power availability during an No Plant currently uses batteries fuel cells. SBO. rather than fuel cells.

Evaluate in Phase II.

Callaway Plant Unit 1 Environmental Report for License Renewal F-79

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 5 Provide DC bus cross-ties. Improved availability of DC power system. No No existing capability for DC bus cross-ties. Evaluate in Phase II.

11 Improve 4.16-kV bus cross-tie Increased availability of on-site AC power. No Evaluate during Phase II ability.

15 Install tornado protection on gas Increased availability of on-site AC power. No No gas turbine currently turbine generator. installed. No tornado protection for Alternate Emergency Power System diesel generators. Evaluate in Phase II.

24 Bury off-site power lines. Improved off-site power reliability during No Evaluate during Phase II severe weather.

25 Install an independent active or Improved prevention of core melt sequences. No Evaluate during Phase II passive high pressure injection system.

26 Provide an additional high pressure Reduced frequency of core melt from small No Evaluate during Phase II injection pump with independent LOCA and SBO sequences.

diesel.

28 Add a diverse low pressure Improved injection capability. No Evaluate during Phase II injection system.

29 Provide capability for alternate Improved injection capability. No Currently being evaluated by injection via diesel-driven fire plant improvement program.

pump. Would use unborated water and portable pump (fire truck).

Calculation of specific benefit of this SAMA was not performed since it is judged to be potentially low cost.

Evaluation will consider impacts of injection of non-borated water.

39 Replace two of the four electric Reduced common cause failure of the safety No Evaluate during Phase II safety injection pumps with diesel- injection system. This SAMA was originally powered pumps. intended for the Westinghouse-CE System 80+, which has four trains of safety injection.

However, the intent of this SAMA is to provide diversity within the high- and l Callaway Plant Unit 1 Environmental Report for License Renewal F-80

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 41 Create a reactor coolant Allows low pressure emergency core cooling No Evaluate during Phase II depressurization system. system injection in the event of small LOCA and high-pressure safety injection failure.

43 Add redundant DC control power Increased availability of SW. No Evaluate during Phase II for SW pumps.

46 Add a service water pump. Increased availability of cooling water. No Evaluate during Phase II 54 Increase charging pump lube oil Increased time before charging pump failure No Evaluate during Phase II capacity. due to lube oil overheating in loss of cooling water sequences.

55 Install an independent reactor Reduced frequency of core damage from No Evaluate during Phase II coolant pump seal injection system, loss of component cooling water, service with dedicated diesel. water, or station blackout.

56 Install an independent reactor Reduced frequency of core damage from No Evaluate during Phase II coolant pump seal injection system, loss of component cooling water or service without dedicated diesel. water, but not a station blackout.

58 Install improved reactor coolant Reduced likelihood of reactor coolant pump No Evaluate in Phase II.

pump seals. seal LOCA.

59 Install an additional component Reduced likelihood of loss of component No Evaluate during Phase II cooling water pump. cooling water leading to a reactor coolant pump seal LOCA.

64 Implement procedure and hardware Improved ability to cool residual heat removal No Evaluate during Phase II modifications to allow manual heat exchangers.

alignment of the fire water system to the component cooling water system, or install a component cooling water header cross-tie.

65 Install a digital feed water upgrade. Reduced chance of loss of main feed water No Evaluate in Phase II.

following a plant trip.

71 Install a new condensate storage Increased availability of the auxiliary No Evaluate during Phase II tank (auxiliary feedwater storage feedwater system.

tank).

77 Provide a passive, secondary-side Reduced potential for core damage due to No Evaluate during Phase II heat-rejection loop consisting of a loss-of-feedwater events.

condenser and heat sink.

79 Replace existing pilot-operated Increased probability of successful feed and No Evaluate during Phase II relief valves with larger ones, such bleed.

that only one is required for successful feed and bleed.

Callaway Plant Unit 1 Environmental Report for License Renewal F-81

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 80 Provide a redundant train or means Increased availability of components No Evaluate during Phase II of ventilation. dependent on room cooling.

87 Replace service and instrument air Elimination of instrument air system No Air compressors currently compressors with more reliable dependence on service water cooling. cooled by ESW. Evaluate in compressors which have self- Phase II.

contained air cooling by shaft driven fans.

91 Install a passive containment spray Improved containment spray capability. No Evaluate during Phase II system.

93 Install an unfiltered, hardened Increased decay heat removal capability for No Evaluate during Phase II containment vent. non-ATWS events, without scrubbing released fission products.

94 Install a filtered containment vent to Increased decay heat removal capability for No Evaluate during Phase II remove decay heat. Option 1: non-ATWS events, with scrubbing of Gravel Bed Filter; Option 2: released fission products.

Multiple Venturi Scrubber 96 Provide post-accident containment Reduced likelihood of hydrogen and carbon No Evaluate during Phase II inerting capability. monoxide gas combustion.

97 Create a large concrete crucible Increased cooling and containment of molten No Evaluate during Phase II with heat removal potential to core debris. Molten core debris escaping contain molten core debris. from the vessel is contained within the crucible and a water cooling mechanism cools the molten core in the crucible, preventing melt-through of the base mat.

98 Create a core melt source Increased cooling and containment of molten No Evaluate during Phase II reduction system. core debris. Refractory material would be placed underneath the reactor vessel such that a molten core falling on the material would melt and combine with the material.

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

99 Strengthen primary/secondary Reduced probability of containment over- No Evaluate during Phase II containment (e.g., add ribbing to pressurization.

containment shell).

100 Increase depth of the concrete Reduced probability of base mat melt- No Evaluate during Phase II base mat or use an alternate through.

concrete material to ensure melt-through does not occur.

Callaway Plant Unit 1 Environmental Report for License Renewal F-82

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 102 Construct a building to be Reduced probability of containment over- No Evaluate during Phase II connected to primary/secondary pressurization.

containment and maintained at a vacuum.

104 Improve leak detection procedures. Increased piping surveillance to identify leaks No Evaluate during Phase II prior to complete failure. Improved leak detection would reduce LOCA frequency.

107 Install a redundant containment Increased containment heat removal ability. No Evaluate during Phase II spray system.

108 Install an independent power Reduced hydrogen detonation potential. No Evaluate during Phase II supply to the hydrogen control system using either new batteries, a non-safety grade portable generator, existing station batteries, or existing AC/DC independent power supplies, such as the security system diesel.

109 Install a passive hydrogen control Reduced hydrogen detonation potential. No Evaluate during Phase II system.

110 Erect a barrier that would provide Reduced probability of containment failure. No Evaluate during Phase II enhanced protection of the containment walls (shell) from ejected core debris following a core melt scenario at high pressure.

111 Install additional pressure or leak Reduced ISLOCA frequency. No Evaluate during Phase II monitoring instruments for detection of ISLOCAs.

112 Add redundant and diverse limit Reduced frequency of containment isolation No Evaluate during Phase II switches to each containment failure and ISLOCAs.

isolation valve.

113 Increase leak testing of valves in Reduced ISLOCA frequency. No Evaluate during Phase II ISLOCA paths.

114 Install self-actuating containment Reduced frequency of isolation failure. No Evaluate during Phase II isolation valves.

115 Locate residual heat removal Reduced frequency of ISLOCA outside No Evaluate during Phase II (RHR) inside containment containment.

Callaway Plant Unit 1 Environmental Report for License Renewal F-83

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 116 Ensure ISLOCA releases are Scrubbed ISLOCA releases. No Evaluate during Phase II scrubbed. One method is to plug drains in potential break areas so that break point will be covered with water.

119 Institute a maintenance practice to Reduced frequency of steam generator tube No Current frequency of perform a 100% inspection of ruptures. inspection of SG tubes is steam generator tubes during each 100% inspection every third refueling outage. outage.

Evaluate during Phase II 121 Increase the pressure capacity of Eliminates release pathway to the No Evaluate during Phase II the secondary side so that a steam environment following a steam generator generator tube rupture would not tube rupture.

cause the relief valves to lift.

122 Install a redundant spray system to Enhanced depressurization capabilities No Evaluate during Phase II depressurize the primary system during steam generator tube rupture.

during a steam generator tube rupture 125 Route the discharge from the main Reduced consequences of a steam No Evaluate during Phase II steam safety valves through a generator tube rupture.

structure where a water spray would condense the steam and remove most of the fission products.

126 Install a highly reliable (closed loop) Reduced consequences of a steam No Evaluate during Phase II steam generator shell-side heat generator tube rupture.

removal system that relies on natural circulation and stored water sources 129 Vent main steam safety valves in Reduced consequences of a steam No Evaluate during Phase II containment. generator tube rupture.

130 Add an independent boron injection Improved availability of boron injection during No Evaluate during Phase II system. ATWS.

131 Add a system of relief valves to Improved equipment availability after an No Evaluate during Phase II prevent equipment damage from ATWS.

pressure spikes during an ATWS.

133 Install an ATWS sized filtered Increased ability to remove reactor heat from No Evaluate during Phase II containment vent to remove decay ATWS events.

heat.

Callaway Plant Unit 1 Environmental Report for License Renewal F-84

Attachment F Severe Accident Mitigation Alternatives Table 6-1. Callaway Plant Phase I SAMA Analysis (Continued)

Callaway SAMA Screened Number Potential Improvement Discussion Out Ph 1? Screening Criterion Phase I Disposition 136 Install motor generator set trip Reduced frequency of core damage due to No Evaluate in Phase II.

breakers in control room. an ATWS.

147 Install digital large break LOCA Reduced probability of a large break LOCA No Evaluate during Phase II protection system. (a leak before break).

153 Install secondary side guard pipes Prevents secondary side depressurization No Evaluate during Phase II up to the main steam isolation should a steam line break occur upstream of valves. the main steam isolation valves. Also guards against or prevents consequential multiple steam generator tube ruptures following a main steam line break event.

160 Modifications to lessen impact of Lower impact of flood that propagates No Evaluate in Phase II internal flooding path through through the dumbwaiter Control Building dumbwaiter.

161 Improvements to PORV Decrease in risk due to PORV failing to open. No Evaluate in Phase II.

performance that will lower the probability of failure to open.

162 Install a large volume EDG fuel oil Allows transfer of EDF fuel oil to the EDG No Evaluate in Phase II.

tank at an elevation greater than day tanks on failure of the fuel oil transfer the EDG fuel oil day tanks. pumps.

163 Improve feedwater check valve Lower risk due to failures in which feedwater No Valves replaced with new reliability to reduce probability of check valves fail to open and allow feeding of type, but are still significant failure to open. the steam generators. risk contributor. Evaluate in Phase II.

164 Provide the capability to power the Provide backup to ESW in conditions with No Evaluate in Phase II.

normal service water pumps from power only available from AEPS.

AEPS.

171 Increase the size of the RWST or Ensure a supply of makeup water is available No Evaluate in Phase II.

otherwise improve the availability of from the RWST.

the RWST Callaway Plant Unit 1 Environmental Report for License Renewal F-85

Attachment F Severe Accident Mitigation Alternatives 7.0 PHASE II SAMA ANALYSIS A cost-benefit analysis was performed on each of the SAMA candidates remaining after the Phase I screening. The benefit of a SAMA candidate is the difference between the baseline cost of severe accident risk (maximum benefit from Section 4.5) and the cost of severe accident risk with the SAMA implemented (Section 7.1). The cost figure used is the estimated cost to implement the specific SAMA. If the estimated cost of implementation exceeds the benefit of implementation, the SAMA is not cost-beneficial.

7.1 SAMA BENEFIT 7.1.1 Severe Accident Risk with SAMA Implemented Bounding analyses were used to determine the change in risk following implementation of SAMA candidates or groups of similar SAMA candidates. For each analysis case, the Level 1 internal events or Level 2 PRA models were altered to conservatively consider implementation of the SAMA candidate(s). Then, severe accident risk measures were calculated using the same procedure used for the baseline case described in Section 3. The changes made to the PRA models for each analysis case are described in the annex, Section 11.

Bounding analyses are exemplified by the following:

LBLOCA This analysis case was used to evaluate the change in plant risk profile that would be achieved if a digital large break LOCA protection system was installed. Although the proposed change would not completely eliminate the potential for a large break LOCA, a bounding benefit was estimated by removing the large break LOCA initiating event. This analysis case was used to model the benefit of SAMAs that deal with mitigation of large LOCA events.

DCPWR This analysis case was used to evaluate plant modifications that would increase the availability of Class 1E DC power (e.g., increased battery capacity or the installation of a diesel-powered generator that would effectively increase battery capacity). Although the proposed SAMAs would not completely eliminate the potential failure, a bounding benefit was estimated by removing the battery discharge events and battery failure events. This analysis case was used to model the benefit of SAMAs that deal with mitigation of station blackout events regarding extending the availability of DC power.

The severe accident risk measures were obtained for each analysis case by modifying the baseline model in a simple manner to capture the effect of implementation of the SAMA in a bounding manner. Bounding analyses are very conservative and result in overestimation of the benefit of the candidate analyzed. However, if this bounding assessment yields a benefit that is smaller than the cost of implementation, then the effort involved in refining the PRA modeling approach for the SAMA would be unnecessary because it would only yield a lower benefit result. If the benefit is greater than the cost when modeled in this bounding approach, it is necessary to refine the PRA model of the SAMA to remove the excess conservatism. As a result of this modeling approach, models representing the Phase II SAMAs will not all be at the Callaway Plant Unit 1 Environmental Report for License Renewal F-86

Attachment F Severe Accident Mitigation Alternatives same level of detail and if any are implemented, the PRA result after implementation of the final installed design will differ from the screening-type analyses done during this evaluation.

7.1.2 Cost of Severe Accident Risk with SAMA Implemented Using the risk measures determined as described in Section 7.1.1, severe accident impacts in four areas (offsite exposure cost, off-site economic cost, on-site exposure cost, and on-site economic cost) were calculated using the same procedure used for the baseline case described in Section 4. As in Section 4.5, the severe accident impacts were summed to estimate the total cost of severe accident risk with the SAMA implemented.

7.1.3 SAMA Benefit Calculation The respective SAMA benefit was calculated by subtracting the total cost of severe accident risk with the SAMA implemented from the baseline cost of severe accident risk (maximum benefit from Section 4.5). The estimated benefit for each SAMA candidate is listed in Table 7-1. The calculation of the benefit is performed using an Excel spreadsheet.

7.2 COST OF SAMA IMPLEMENTATION The final step in the evaluation of the SAMAs is estimating the cost of implementation for comparison with the benefit. For the purpose of this analysis the Callaway staff has estimated that the cost of making a change to a procedure and for conducting the necessary training on a procedure change is expected to exceed $15,000. Similarly, the minimum cost associated with development and implementation of an integrated hardware modification package (including post-implementation costs, e.g. training) is expected to exceed $100,000. These values were used for initial comparison with the benefit of SAMAs.

The benefits resulting from the bounding estimates presented in the benefit analysis are in some cases rather low. In those cases for which the benefits are so low that it is obvious that the implementation costs would exceed the benefit, a detailed cost estimate was not warranted.

Plant staff judgment is applied in assessing whether the benefit approaches the expected implementation costs in many cases.

Plant staff judgment was obtained from an independent, expert panel consisting of senior staff members from the PRA group, the design group, operations and license renewal. This panel reviewed the benefit calculation results and, based upon their experience with developing and implementing modifications at the plant, judged whether a modification could be made to the plant that would be cost beneficial in comparison with the calculated benefit. The purpose of this approach was to minimize the effort expended on detailed cost estimation. The cost estimations provided by the expert panel are included in Table 7-1 along with the conclusions reached for each SAMA evaluated for cost/benefit.

The results of the sensitivity analyses are presented in Section 8. The sensitivity analyses did not identify any cost-benefit conclusions affected by uncertainties.

Callaway Plant Unit 1 Environmental Report for License Renewal F-87

Attachment F Severe Accident Mitigation Alternatives Table 7-1. Callaway Plant 1 Phase II SAMA Analysis Callaway  % Red.

SAMA  % Red. In OS SAMA SAMA Case Number Potential Improvement Discussion In CDF Dose Case Description Benefit Cost Cost Basis Evaluation Basis for Evaluation 1 Provide additional DC battery Extended DC power 0.30% 0.00% DC01 TDAFW no DC $1K >$100K Expert Not Cost- Cost will exceed benefit.

capacity. availability during an SBO. Dependency Panel Beneficial 2 Replace lead-acid batteries Extended DC power 12.17% 10.87% NOSBO No Station Blackout $360K >$1M Expert Not Cost- Cost will exceed benefit.

with fuel cells. availability during an SBO. Events Panel Beneficial 5 Provide DC bus cross-ties. Improved availability of DC 0.30% 0.00% DC01 TDAFW no DC $1K >$199K Expert Not Cost- Cost will exceed benefit.

power system. Dependency Panel Beneficial 11 Improve 4.16-kV bus cross- Increased availability of on- 12.17% 10.87% NOSBO No Station Blackout $360K >$1M Expert Not Cost- Cost will exceed benefit.

tie ability. site AC power. Events Panel Beneficial Cost for implementation includes analysis, material to be purchased and prestaged, development of procedures, and training of personnel on implementation.,

15 Install tornado protection on Increased availability of on- 2.65% 4.35% LOSP1 No tornado related $91K >$500K Expert Not Cost- Cost will exceed benefit.

gas turbine generator. site AC power. LOSP Panel Beneficial 24 Bury off-site power lines. Improved off-site power 40.66% 41.30% NOLOSP Eliminate all Loss of $1.2M >$3M Expert Not Cost- Cost will exceed benefit.

reliability during severe Offsite Power Events Panel Beneficial Previous SAMA submittals weather. have estimated approximately $1M per mile.

25 Install an independent active Improved prevention of 2.77% 0.00% LOCA12 No failures of the $48K >$1M Expert Not Cost- Cost will exceed benefit.

or passive high pressure core melt sequences. charging or SI pumps Panel Beneficial injection system.

26 Provide an additional high Reduced frequency of core 2.77% 0.00% LOCA12 No failures of the $48K >$1M Expert Not Cost- Cost will exceed benefit.

pressure injection pump with melt from small LOCA and charging or SI pumps Panel Beneficial independent diesel. SBO sequences.

28 Add a diverse low pressure Improved injection 3.19% 2.17% LOCA03 No failure of low $65K >$1M Expert Not Cost- Cost will exceed benefit.

injection system. capability. pressure injection Panel Beneficial 29 Provide capability for Improved injection Potentially SAMA is judged to be low alternate injection via diesel- capability. Cost- cost, but analysis is driven fire pump. Beneficial needed to determine impacts of injection of non-borated water to RCS.

Expert Panel judged this SAMA to be potentially cost-beneficial without determining an actual benefit or cost.

Callaway Plant Unit 1 Environmental Report for License Renewal F-88

Attachment F Severe Accident Mitigation Alternatives Table 7-1. Callaway Plant 1 Phase II SAMA Analysis (Continued)

Callaway  % Red.

SAMA  % Red. In OS SAMA SAMA Case Number Potential Improvement Discussion In CDF Dose Case Description Benefit Cost Cost Basis Evaluation Basis for Evaluation 39 Replace two of the four Reduced common cause 2.77% 0.00% LOCA12 No failures of the $748K >$1M Expert Not Cost- Cost will exceed benefit.

electric safety injection failure of the safety charging or SI pumps Panel Beneficial pumps with diesel-powered injection system. This pumps. SAMA was originally intended for the Westinghouse-CE System 80+, which has four trains of safety injection.

However, the intent of this SAMA is to provide diversity within the high-and l 41 Create a reactor coolant Allows low pressure 0.78% 0.00% DEPRESS No failures of $12K >$500K Expert Not Cost- Cost will exceed benefit.

depressurization system. emergency core cooling depressurization Panel Beneficial system injection in the event of small LOCA and high-pressure safety injection failure.

43 Add redundant DC control Increased availability of 0.30% 0.00% SW01 Service Water Pumps $1K >$100K Expert Not Cost- Cost will exceed benefit.

power for SW pumps. SW. not dependent on DC Panel Beneficial Power 46 Add a service water pump. Increased availability of 12.35% 21.74% SW02 No failures of ESW $464K >$5M Expert Not Cost- Cost will exceed benefit.

cooling water. pumps Panel Beneficial 54 Increase charging pump lube Increased time before 0.48% 0.00% CHG01 Charging pumps not $4K >$100K Expert Not Cost- Cost will exceed benefit.

oil capacity. charging pump failure due dependent on cooling Panel Beneficial to lube oil overheating in water.

loss of cooling water sequences.

55 Install an independent Reduced frequency of core 5.54% 0.00% RCPLOCA No RCP Seal LOCAs $94K >$1M Expert Not Cost- Cost will exceed benefit.

reactor coolant pump seal damage from loss of Panel Beneficial Previous investigation into injection system, with component cooling water, installing such a system dedicated diesel. service water, or station concluded that operators blackout. did not have sufficient time to place the system in service prior to seal damage.

56 Install an independent Reduced frequency of core 5.54% 0.00% RCPLOCA No RCP Seal LOCAs $94K >$500K Expert Not Cost- Cost will exceed benefit.

reactor coolant pump seal damage from loss of Panel Beneficial injection system, without component cooling water dedicated diesel. or service water, but not a station blackout.

58 Install improved reactor Reduced likelihood of 5.54% 0.00% RCPLOCA No RCP Seal LOCAs $94K >$3M Not Cost- Cost will exceed benefit.

coolant pump seals. reactor coolant pump seal Beneficial LOCA.

59 Install an additional Reduced likelihood of loss 3.61% 0.00% CCW01 No failures of the CCW $59K >$1M Cost will Not Cost- Cost will exceed benefit.

component cooling water of component cooling water Pumps exceed Beneficial pump. leading to a reactor coolant benefit pump seal LOCA.

Callaway Plant Unit 1 Environmental Report for License Renewal F-89

Attachment F Severe Accident Mitigation Alternatives Table 7-1. Callaway Plant 1 Phase II SAMA Analysis (Continued)

Callaway  % Red.

SAMA  % Red. In OS SAMA SAMA Case Number Potential Improvement Discussion In CDF Dose Case Description Benefit Cost Cost Basis Evaluation Basis for Evaluation 64 Implement procedure and Improved ability to cool 3.61% 0.00% CCW01 No failures of the CCW $59K >$500K Expert Not Cost- Cost will exceed benefit.

hardware modifications to residual heat removal heat Pumps Panel Beneficial allow manual alignment of exchangers.

the fire water system to the component cooling water system, or install a component cooling water header cross-tie.

65 Install a digital feed water Reduced chance of loss of 1.57% 0.00% FW01 No loss of Feedwater $29K $19M Callaway Not Cost- Cost will exceed benefit.

upgrade. main feed water following a Events Modification Beneficial plant trip. Costs 71 Install a new condensate Increased availability of the 1.14% 0.00% CST01 CST does not deplete $18K >$2.5M Expert Not Cost- Cost will exceed benefit.

storage tank (auxiliary auxiliary feedwater system. Panel Beneficial feedwater storage tank).

77 Provide a passive, Reduced potential for core 1.57% 0.00% FW01 No loss of Feedwater $29K $>1M Expert Not Cost- Cost will exceed benefit.

secondary-side heat- damage due to loss-of- Events Panel Beneficial rejection loop consisting of a feedwater events.

condenser and heat sink.

79 Replace existing pilot- Increased probability of 3.43% 2.17% FB01 Only one PORV $79K >$500K Expert Not Cost- Cost will exceed benefit.

operated relief valves with successful feed and bleed. required for Feed & Panel Beneficial larger ones, such that only Bleed one is required for successful feed and bleed.

80 Provide a redundant train or Increased availability of 6.08% 4.35% HVAC No dependencies on $156K >$1M Expert Not Cost- Cost will exceed benefit.

means of ventilation. components dependent on HVAC Panel Beneficial room cooling.

87 Replace service and Elimination of instrument 0.36% 0.00% INSTAIR Eliminate all instrument $2K >$500K Expert Not Cost- Cost will exceed benefit.

instrument air compressors air system dependence on air failures Panel Beneficial with more reliable service water cooling.

compressors which have self-contained air cooling by shaft driven fans.

91 Install a passive containment Improved containment 19.52% 36.96% CONT01 No failures due to $1.2M >$10M Expert Not Cost- Cost will exceed benefit.

spray system. spray capability. containment Panel Beneficial overpressure 93 Install an unfiltered, Increased decay heat 19.52% 36.96% CONT01 No failures due to $1.2M >$2M Expert Not Cost- Cost will exceed benefit.

hardened containment vent. removal capability for non- containment Panel Beneficial ATWS events, without overpressure scrubbing released fission products.

94 Install a filtered containment Increased decay heat 19.52% 36.96% CONT01 No failures due to $1.2M >$2M Expert Not Cost- Cost will exceed benefit.

vent to remove decay heat. removal capability for non- containment Panel Beneficial Option 1: Gravel Bed Filter; ATWS events, with overpressure Option 2: Multiple Venturi scrubbing of released Scrubber fission products.

96 Provide post-accident Reduced likelihood of 0.48% 0.00% H2BURN No hydrogen $10K >$100K Expert Not Cost- Cost will exceed benefit.

containment inerting hydrogen and carbon burns/explosions Panel Beneficial capability. monoxide gas combustion.

Callaway Plant Unit 1 Environmental Report for License Renewal F-90

Attachment F Severe Accident Mitigation Alternatives Table 7-1. Callaway Plant 1 Phase II SAMA Analysis (Continued)

Callaway  % Red.

SAMA  % Red. In OS SAMA SAMA Case Number Potential Improvement Discussion In CDF Dose Case Description Benefit Cost Cost Basis Evaluation Basis for Evaluation 97 Create a large concrete Increased cooling and MAB >$10M Expert Not Cost- Cost will exceed benefit.

crucible with heat removal containment of molten core Panel Beneficial potential to contain molten debris. Molten core debris core debris. escaping from the vessel is contained within the crucible and a water cooling mechanism cools the molten core in the crucible, preventing melt-through of the base mat.

98 Create a core melt source Increased cooling and MAB >$10M Expert Not Cost- Cost will exceed benefit.

reduction system. containment of molten core Panel Beneficial debris. Refractory material would be placed underneath the reactor vessel such that a molten core falling on the material would melt and combine with the material.

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

99 Strengthen Reduced probability of 19.52% 36.96% CONT01 No failures due to $1.2M >$10M Expert Not Cost- Cost will exceed benefit.

primary/secondary containment over- containment Panel Beneficial containment (e.g., add pressurization. overpressure ribbing to containment shell).

100 Increase depth of the Reduced probability of MAB >$10M Expert Not Cost- Cost will exceed benefit.

concrete base mat or use an base mat melt-through. Panel Beneficial alternate concrete material to ensure melt-through does not occur.

102 Construct a building to be Reduced probability of 19.52% 36.96% CONT01 No failures due to $1.2M >$10M Expert Not Cost- Cost will exceed benefit.

connected to containment over- containment Panel Beneficial primary/secondary pressurization. overpressure containment and maintained at a vacuum.

104 Improve leak detection Increased piping 39.34% 2.17% LOCA05 No piping system $689K >$2M Expert Not Cost- Cost will exceed benefit.

procedures. surveillance to identify LOCAs Panel Beneficial leaks prior to complete failure. Improved leak detection would reduce LOCA frequency.

107 Install a redundant Increased containment 19.52% 36.96% CONT01 No failures due to $1.2M >$2M Expert Not Cost- Cost will exceed benefit.

containment spray system. heat removal ability. containment Panel Beneficial overpressure Callaway Plant Unit 1 Environmental Report for License Renewal F-91

Attachment F Severe Accident Mitigation Alternatives Table 7-1. Callaway Plant 1 Phase II SAMA Analysis (Continued)

Callaway  % Red.

SAMA  % Red. In OS SAMA SAMA Case Number Potential Improvement Discussion In CDF Dose Case Description Benefit Cost Cost Basis Evaluation Basis for Evaluation 108 Install an independent power Reduced hydrogen 0.48% 0.00% H2BURN No hydrogen $10K >$100K Expert Not Cost-supply to the hydrogen detonation potential. burns/explosions Panel Beneficial control system using either new batteries, a non-safety grade portable generator, existing station batteries, or existing AC/DC independent power supplies, such as the security system diesel.

109 Install a passive hydrogen Reduced hydrogen 0.48% 0.00% H2BURN No hydrogen $10K >$100M Expert Not Cost- Cost will exceed benefit.

control system. detonation potential. burns/explosions Panel Beneficial 110 Erect a barrier that would Reduced probability of MAB >$10M Expert Not Cost- Cost will exceed benefit.

provide enhanced protection containment failure. Panel Beneficial of the containment walls (shell) from ejected core debris following a core melt scenario at high pressure.

111 Install additional pressure or Reduced ISLOCA 1.33% 8.70% ISLOCA No ISLOCA events $123K >$500K Expert Not Cost- Cost will exceed benefit.

leak monitoring instruments frequency. Panel Beneficial for detection of ISLOCAs.

112 Add redundant and diverse Reduced frequency of 0.30% 0.00% CONT02 No failures of $1K >$1M Expert Not Cost- Cost will exceed benefit.

limit switches to each containment isolation containment isolation Panel Beneficial containment isolation valve. failure and ISLOCAs.

113 Increase leak testing of Reduced ISLOCA 1.33% 8.70% ISLOCA No ISLOCA events $123K >$1M Expert Not Cost- Cost will exceed benefit.

valves in ISLOCA paths. frequency. Panel Beneficial 114 Install self-actuating Reduced frequency of 0.30% 0.00% CONT02 No failures of $1K >$500K Expert Not Cost- Cost will exceed benefit.

containment isolation valves. isolation failure. containment isolation Panel Beneficial 115 Locate residual heat removal Reduced frequency of 1.33% 8.70% ISLOCA No ISLOCA events $123K >$1M Expert Not Cost- Cost will exceed benefit.

(RHR) inside containment ISLOCA outside Panel Beneficial containment.

116 Ensure ISLOCA releases are Scrubbed ISLOCA 1.33% 8.70% ISLOCA No ISLOCA events $123K >$1M Expert Not Cost- Cost would exceed benefit.

scrubbed. One method is to releases. Panel Beneficial Current plant design plug drains in potential break requires drains to be open.

areas so that break point will Analysis and license be covered with water. changes required to implement are included in the cost estimate.

119 Institute a maintenance Reduced frequency of 15.66% 52.17% NOSGTR No SGTR Events $1.2M >$3M Expert Not Cost- Cost will exceed benefit.

practice to perform a 100% steam generator tube Panel Beneficial inspection of steam ruptures.

generator tubes during each refueling outage.

121 Increase the pressure Eliminates release pathway 15.66% 52.17% NOSGTR No SGTR Events $1.2M >$10M Expert Not Cost- Cost will exceed benefit.

capacity of the secondary to the environment Panel Beneficial side so that a steam following a steam generator tube rupture would generator tube rupture.

not cause the relief valves to lift.

122 Install a redundant spray Enhanced depressurization 15.66% 52.17% NOSGTR No SGTR Events $1.2M >$10M Expert Not Cost- Cost will exceed benefit.

system to depressurize the capabilities during steam Panel Beneficial primary system during a generator tube rupture.

steam generator tube rupture Callaway Plant Unit 1 Environmental Report for License Renewal F-92

Attachment F Severe Accident Mitigation Alternatives Table 7-1. Callaway Plant 1 Phase II SAMA Analysis (Continued)

Callaway  % Red.

SAMA  % Red. In OS SAMA SAMA Case Number Potential Improvement Discussion In CDF Dose Case Description Benefit Cost Cost Basis Evaluation Basis for Evaluation 125 Route the discharge from the Reduced consequences of 15.66% 52.17% NOSGTR No SGTR Events $1.2M >$10M Expert Not Cost- Cost will exceed benefit.

main steam safety valves a steam generator tube Panel Beneficial through a structure where a rupture.

water spray would condense the steam and remove most of the fission products.

126 Install a highly reliable Reduced consequences of 15.66% 52.17% NOSGTR No SGTR Events $1.2M >$10M Expert Not Cost- Cost will exceed benefit.

(closed loop) steam a steam generator tube Panel Beneficial generator shell-side heat rupture.

removal system that relies on natural circulation and stored water sources 129 Vent main steam safety Reduced consequences of 15.66% 52.17% NOSGTR No SGTR Events $1.2M >$10M Expert Not Cost- Cost will exceed benefit.

valves in containment. a steam generator tube Panel Beneficial Current containment rupture. design does not support this modification.

Modifications to containment and associated analysis are included in the cost estimate.

130 Add an independent boron Improved availability of 2.41% 2.17% NOATWS Eliminate all ATWS $63K >$1M Expert Not Cost- Cost will exceed benefit.

injection system. boron injection during Panel Beneficial ATWS.

131 Add a system of relief valves Improved equipment 2.41% 2.17% NOATWS Eliminate all ATWS $63K >$2M Expert Not Cost- Cost will exceed benefit.

to prevent equipment availability after an ATWS. Panel Beneficial damage from pressure spikes during an ATWS.

133 Install an ATWS sized filtered Increased ability to remove 2.41% 2.17% NOATWS Eliminate all ATWS $63K >$1M Expert Not Cost- Cost will exceed benefit containment vent to remove reactor heat from ATWS Panel Beneficial decay heat. events.

136 Install motor generator set Reduced frequency of core 2.41% 2.17% NOATWS Eliminate all ATWS $53K >$500K Expert Not Cost- Cost will exceed benefit.

trip breakers in control room. damage due to an ATWS. Panel Beneficial 147 Install digital large break Reduced probability of a 39.34% 2.17% LOCA05 No piping system $689K >$5M Expert Not Cost- Cost will exceed benefit.

LOCA protection system. large break LOCA (a leak LOCAs Panel Beneficial before break).

153 Install secondary side guard Prevents secondary side 2.53% 0.00% NOSLB No Steam Line Breaks $51K >$1M Expert Not Cost- Cost will exceed benefit.

pipes up to the main steam depressurization should a Panel Beneficial isolation valves. steam line break occur upstream of the main steam isolation valves.

Also guards against or prevents consequential multiple steam generator tube ruptures following a main steam line break event.

Callaway Plant Unit 1 Environmental Report for License Renewal F-93

Attachment F Severe Accident Mitigation Alternatives Table 7-1. Callaway Plant 1 Phase II SAMA Analysis (Continued)

Callaway  % Red.

SAMA  % Red. In OS SAMA SAMA Case Number Potential Improvement Discussion In CDF Dose Case Description Benefit Cost Cost Basis Evaluation Basis for Evaluation 160 Modifications to lessen Lower impact of flood that <$50K Expert Potentially Relatively minor impact of internal flooding propagates through the Panel Cost- modifications to door path through Control Building dumbwaiter Beneficial opening could result in dumbwaiter. lower flow to the dumbwaiter. Specific benefit could not be calculated but SAMA item is judged to be low cost and therefore potentially cost beneficial.

161 Improvements to PORV Decrease in risk due to PORV PORVs do not fail to $18K >$100K Expert Not Cost- Cost will exceed benefit.

performance that will lower PORV failing to open. open Panel Beneficial the probability of failure to open.

162 Install a large volume EDG Allows transfer of EDF fuel EDGFUEL No EDG fuel pump $124K $150K Wolf Creek Potentially Wolf Creek estimated cost fuel oil tank at an elevation oil to the EDG day tanks on failures Cost- of $150K is less than the greater than the EDG fuel oil failure of the fuel oil Beneficial potential benefit.

day tanks. transfer pumps.

163 Improve feedwater check Lower risk due to failures in FW02 Feedwater Check $127K >$500K Expert Not Cost- Cost will exceed benefit.

valve reliability to reduce which feedwater check Valves do not fail to Panel Beneficial probability of failure to open. valves fail to open and open allow feeding of the steam generators.

164 Provide the capability to Provide backup to ESW in SW03 AEPS power to SW $191K >$500K Expert Not Cost- Cost will exceed benefit.

power the normal service conditions with power only pumps Panel Beneficial water pumps from AEPS. available from AEPS.

171 Increase the size of the Ensure a supply of makeup LOCA04 RWST does not $13K >$100K Expert Not Cost- Cost will exceed benefit.

RWST or otherwise improve water is available from the deplete Panel Beneficial the availability of the RWST RWST.

OS = off site Callaway Plant Unit 1 Environmental Report for License Renewal F-94

Attachment F Severe Accident Mitigation Alternatives 8.0 SENSITIVITY ANALYSES The purpose of performing sensitivity analyses is to examine the impact of analysis assumptions on the results of the SAMA evaluation. This section identifies several sensitivities that can be considered in SAMA analysis (Reference 19, NEI 05-01) and discusses the sensitivity as is applies to Callaway Plant and the impact of the sensitivity on the results of the Phase II SAMA analysis at Callaway.

Unless it was otherwise noted, it is assumed in these sensitivity analyses that sufficient margin existed in the maximum benefit estimation that the Phase I screening would not have to be repeated in the sensitivity analyses.

8.1 PLANT MODIFICATIONS There are no plant modifications that are currently pending that would be expected to impact the results of this SAMA evaluation.

8.2 UNCERTAINTY Since the inputs to PRA cannot be known with complete certainty, there is possibility that the actual plant risk is greater than the point estimate values used in the evaluation of the SAMA described in the previous sections. To consider this uncertainty, a sensitivity analysis was performed in which an uncertainty factor was applied to the frequencies calculated by the PRA and the subsequent benefits were calculated based upon the point estimate risk values multiplied by this uncertainty factor. The uncertainty factor applied is the ratio of the 95th percentile value of the CDF from the PRA uncertainty analysis to the mean value of the CDF.

For Callaway the 95th percentile value of the CDF is 3.50E-5/yr; therefore, uncertainty factor is 2.11. Table 8-1 provides the benefit results from each of the sensitivities for each of the SAMA cases evaluated.

8.3 PEER REVIEW FACTS/OBSERVATIONS The model used in this SAMA analysis includes the resolution of the Facts-and-Observations (F&Os) identified during the PRA Peer Review. Therefore, no specific sensitivities were performed related to this issue.

8.4 EVACUATION SPEED Two evacuation sensitivity cases were performed to determine the impact of evacuation assumptions. The Callaway base case assumes a delay time of 105 minutes prior to evacuation to address public notification, trip time home after notification, and trip preparation time (e.g., loading vehicles) and an average evacuation speed of 2.14 meters/sec (4.8 mph).

Both values are based on data provided in the Callaway Evacuation Time Estimate study.

Two evacuation sensitivity cases were evaluated. The first sensitivity case evaluates the impact of an increased delay time before evacuation begins (i.e., vehicles begin moving in the 10 mile region). For this sensitivity, the base case delay time of 105 minutes is doubled to 210 minutes.

The increased delay time results in an increase in dose risk of about 2.4%. An increase in dose Callaway Plant Unit 1 Environmental Report for License Renewal F-95

Attachment F Severe Accident Mitigation Alternatives risk is generally expected because more individuals would be expected be exposed to the release due to their later departure (i.e., they failed to out run the release).

The second sensitivity case assesses the impact of evacuation speed assumptions by reducing the evacuation speed by one half, to 1.07 m/s (2.4 mph). The slower evacuation speed increases the dose risk by approximately 7%. An increase in dose risk is generally expected because individuals will tend to be subject to the plumes for a longer period of time when traveling slower. For either evacuation speed, the plumes can be viewed as tending to blow over the evacuees (average wind speed of 7 mph) as the evacuees progress through traffic.

8.5 REAL DISCOUNT RATE Calculation of severe accident impacts in the Callaway SAMA analysis was performed using a real discount rate of 7% (0.07/year) as recommended in Reference 15, NUREG/BR-0184. Use of both a 7% and 3% real discount rate in regulatory analysis is specified in Office of Management Budget (OMB) guidance (Reference 20) and in NUREG/BR-0058 (Reference 21).

Therefore, a sensitivity analysis was performed using a 3% real discount rate.

In this sensitivity analysis, the real discount rate in the Level 3 PRA model was changed to 3%

from 7% and the Phase II analysis was re-performed with the lower interest rate. The analysis was also performed at a realistic discount rate of 8.3%.

The results of this sensitivity analysis are presented in Table 8-1. This sensitivity analysis does not affect any decisions made regarding the SAMAs.

8.6 ANALYSIS PERIOD As described in Section 4, calculation of severe accident impacts involves an analysis period term, t f , which could have been defined as either the period of extended operation (20 years), or the years remaining until the end of facility life (from the time of the SAMA analysis to the end of the period of extended operation) (33 years).

The value used for this term was the period of extended operation (20 years). This sensitivity analysis was performed using the period from the time of the SAMA analysis to the end of the period of extended operation to determine if SAMAs would be potentially cost-beneficial if performed immediately.

In this sensitivity analysis, the analysis period in the calculation of severe accident risk was modified to 33 years and the Phase II analysis was re-performed with the revised analysis period. The cost of additional years of maintenance, surveillance, calibrations, and training were included appropriately in the cost estimates for SAMAs in this Phase II analysis.

The results of this sensitivity analysis are presented in Table 8-1. This sensitivity analysis does not affect any decisions made regarding the SAMAs.

Callaway Plant Unit 1 Environmental Report for License Renewal F-96

Attachment F Severe Accident Mitigation Alternatives Table 8-1. Callaway Plant Sensitivity Evaluation Callaway Benefit at Benefit at Benefit SAMA SAMA 3% Disc Realistic Benefit at 95%

Number Potential Improvement Discussion Case Benefit Rate Disc Rate at 33yrs CDF Cost Cost Basis Evaluation Basis for Evaluation 1 Provide additional DC battery Extended DC power availability DC01 $1K $1K $1K $1K $1K >$100K Expert Panel Not Cost- Cost will exceed capacity. during an SBO. Beneficial benefit.

2 Replace lead-acid batteries with fuel Extended DC power availability NOSBO $360K $588K $325K $512K $761K >$1M Expert Panel Not Cost- Cost will exceed cells. during an SBO. Beneficial benefit.

5 Provide DC bus cross-ties. Improved availability of DC DC01 $1K $1K $1K $1K $1K >$199K Expert Panel Not Cost- Cost will exceed power system. Beneficial benefit.

11 Improve 4.16-kV bus cross-tie ability. Increased availability of on-site NOSBO $360K $588K $325K $512K $761K >$1M Expert Panel Not Cost- Cost will exceed AC power. Beneficial benefit. Cost for implementation includes analysis, material to be purchased and prestaged, development of procedures, and training of personnel on implementation.,

15 Install tornado protection on gas Increased availability of on-site LOSP1 $91K $144K $82K $125K $192K >$500K Expert Panel Not Cost- Cost will exceed turbine generator. AC power. Beneficial benefit.

24 Bury off-site power lines. Improved off-site power reliability NOLOSP $1.2M $2.0M $1.1M $1.7M $2.6M >$3M Expert Panel Not Cost- Cost will exceed during severe weather. Beneficial benefit. Previous SAMA submittals have estimated approximately $1M per mile.

25 Install an independent active or Improved prevention of core melt LOCA12 $48K $85K $44K $75 $102 >$1M Expert Panel Not Cost- Cost will exceed passive high pressure injection sequences. Beneficial benefit.

system.

26 Provide an additional high pressure Reduced frequency of core melt LOCA12 $48K $85K $44K $75 $102 >$1M Expert Panel Not Cost- Cost will exceed injection pump with independent from small LOCA and SBO Beneficial benefit.

diesel. sequences.

28 Add a diverse low pressure injection Improved injection capability. LOCA03 $65K $111K $58K $97K $137K >$1M Expert Panel Not Cost- Cost will exceed system. Beneficial benefit.

29 Provide capability for alternate Improved injection capability. Potentially SAMA is judged to be injection via diesel-driven fire pump. Cost-Beneficial low cost, but analysis is needed to determine impacts of injection of non-borated water to RCS.

Expert Panel judged this SAMA to be potentially cost-beneficial without determining an actual benefit or cost.

Callaway Plant Unit 1 Environmental Report for License Renewal F-97

Attachment F Severe Accident Mitigation Alternatives Table 8-1. Callaway Plant Sensitivity Evaluation (Continued)

Callaway Benefit at Benefit at Benefit SAMA SAMA 3% Disc Realistic Benefit at 95%

Number Potential Improvement Discussion Case Benefit Rate Disc Rate at 33yrs CDF Cost Cost Basis Evaluation Basis for Evaluation 39 Replace two of the four electric safety Reduced common cause failure LOCA12 $48K $85K $44K $75 $102 >$1M Expert Panel Not Cost- Cost will exceed injection pumps with diesel-powered of the safety injection system. Beneficial benefit.

pumps. This SAMA was originally intended for the Westinghouse-CE System 80+, which has four trains of safety injection.

However, the intent of this SAMA is to provide diversity within the high- and l 41 Create a reactor coolant Allows low pressure emergency DEPRESS $12K $20K $11K $17K $25K >$500K Expert Panel Not Cost- Cost will exceed depressurization system. core cooling system injection in Beneficial benefit.

the event of small LOCA and high-pressure safety injection failure.

43 Add redundant DC control power for Increased availability of SW. SW01 $1K $2K $1K $2K $3K >$100K Expert Panel Not Cost- Cost will exceed SW pumps. Beneficial benefit.

46 Add a service water pump. Increased availability of cooling SW02 $464K $734K $419K $637K $980K >$5M Expert Panel Not Cost- Cost will exceed water. Beneficial benefit.

54 Increase charging pump lube oil Increased time before charging CHG01 $4K $7K $4K $6K $9K >$100K Expert Panel Not Cost- Cost will exceed capacity. pump failure due to lube oil Beneficial benefit.

overheating in loss of cooling water sequences.

55 Install an independent reactor coolant Reduced frequency of core RCPLOCA $94K $168K $85K $148K $198K >$1M Expert Panel Not Cost- Cost will exceed pump seal injection system, with damage from loss of component Beneficial benefit. Previous dedicated diesel. cooling water, service water, or investigation into station blackout. installing such a system concluded that operators did not have sufficient time to place the system in service prior to seal damage.

56 Install an independent reactor coolant Reduced frequency of core RCPLOCA $94K $168K $85K $148K $198K >$500K Expert Panel Not Cost- Cost will exceed pump seal injection system, without damage from loss of component Beneficial benefit.

dedicated diesel. cooling water or service water, but not a station blackout.

58 Install improved reactor coolant pump Reduced likelihood of reactor RCPLOCA $94K $168K $85K $148K $198K >$3M Not Cost- Cost will exceed seals. coolant pump seal LOCA. Beneficial benefit.

59 Install an additional component Reduced likelihood of loss of CCW01 $59K $106K $53K $93K $124K >$1M Cost will Not Cost- Cost will exceed cooling water pump. component cooling water leading exceed Beneficial benefit.

to a reactor coolant pump seal benefit LOCA.

64 Implement procedure and hardware Improved ability to cool residual CCW01 $59K $106K $53K $93K $124K >$500K Expert Panel Not Cost- Cost will exceed modifications to allow manual heat removal heat exchangers. Beneficial benefit.

alignment of the fire water system to the component cooling water system, or install a component cooling water header cross-tie.

65 Install a digital feed water upgrade. Reduced chance of loss of main FW01 $29K $50K $27K $44K $62K $19M Callaway Not Cost- Cost will exceed feed water following a plant trip. Modification Beneficial benefit.

Costs Callaway Plant Unit 1 Environmental Report for License Renewal F-98

Attachment F Severe Accident Mitigation Alternatives Table 8-1. Callaway Plant Sensitivity Evaluation (Continued)

Callaway Benefit at Benefit at Benefit SAMA SAMA 3% Disc Realistic Benefit at 95%

Number Potential Improvement Discussion Case Benefit Rate Disc Rate at 33yrs CDF Cost Cost Basis Evaluation Basis for Evaluation 71 Install a new condensate storage Increased availability of the CST01 $18K $32K $16K $28K $39K >$2.5M Expert Panel Not Cost- Cost will exceed tank (auxiliary feedwater storage auxiliary feedwater system. Beneficial benefit.

tank).

77 Provide a passive, secondary-side Reduced potential for core FW01 $29K $50K $27K $44K $62K $>1M Expert Panel Not Cost- Cost will exceed heat-rejection loop consisting of a damage due to loss-of-feedwater Beneficial benefit.

condenser and heat sink. events.

79 Replace existing pilot-operated relief Increased probability of FB01 $79K $133K $72K $117K $168K >$500K Expert Panel Not Cost- Cost will exceed valves with larger ones, such that successful feed and bleed. Beneficial benefit.

only one is required for successful feed and bleed.

80 Provide a redundant train or means Increased availability of HVAC $156K $259K $141K $227K $331K >$1M Expert Panel Not Cost- Cost will exceed of ventilation. components dependent on room Beneficial benefit.

cooling.

87 Replace service and instrument air Elimination of instrument air INSTAIR $2K $3K $2K $$2K $4K >$500K Expert Panel Not Cost- Cost will exceed compressors with more reliable system dependence on service Beneficial benefit.

compressors which have self- water cooling.

contained air cooling by shaft driven fans.

91 Install a passive containment spray Improved containment spray CONT01 $1.2M $1.2M $717K $1.1M $1.7M >$10M Expert Panel Not Cost- Cost will exceed system. capability. Beneficial benefit.

93 Install an unfiltered, hardened Increased decay heat removal CONT01 $1.2M $1.2M $717K $1.1M $1.7M >$2M Expert Panel Not Cost- Cost will exceed containment vent. capability for non-ATWS events, Beneficial benefit.

without scrubbing released fission products.

94 Install a filtered containment vent to Increased decay heat removal CONT01 $1.2M $1.2M $717K $1.1M $1.7M >$2M Expert Panel Not Cost- Cost will exceed remove decay heat. Option 1: Gravel capability for non-ATWS events, Beneficial benefit.

Bed Filter; Option 2: Multiple Venturi with scrubbing of released fission Scrubber products.

96 Provide post-accident containment Reduced likelihood of hydrogen H2BURN $10K $15K $9K $13K $20K >$100K Expert Panel Not Cost- Cost will exceed inerting capability. and carbon monoxide gas Beneficial benefit.

combustion.

97 Create a large concrete crucible with Increased cooling and MAB >$10M Expert Panel Not Cost- Cost will exceed heat removal potential to contain containment of molten core Beneficial benefit.

molten core debris. debris. Molten core debris escaping from the vessel is contained within the crucible and a water cooling mechanism cools the molten core in the crucible, preventing melt-through of the base mat.

98 Create a core melt source reduction Increased cooling and MAB >$10M Expert Panel Not Cost- Cost will exceed system. containment of molten core Beneficial benefit.

debris. Refractory material would be placed underneath the reactor vessel such that a molten core falling on the material would melt and combine with the material. Subsequent spreading and heat removal from the vitrified compound would be facilitated, and concrete attack would not occur.

Callaway Plant Unit 1 Environmental Report for License Renewal F-99

Attachment F Severe Accident Mitigation Alternatives Table 8-1. Callaway Plant Sensitivity Evaluation (Continued)

Callaway Benefit at Benefit at Benefit SAMA SAMA 3% Disc Realistic Benefit at 95%

Number Potential Improvement Discussion Case Benefit Rate Disc Rate at 33yrs CDF Cost Cost Basis Evaluation Basis for Evaluation 99 Strengthen primary/secondary Reduced probability of CONT01 $1.2M $1.2M $717K $1.1M $1.7M >$10M Expert Panel Not Cost- Cost will exceed containment (e.g., add ribbing to containment over-pressurization. Beneficial benefit.

containment shell).

100 Increase depth of the concrete base Reduced probability of base mat MAB >$10M Expert Panel Not Cost- Cost will exceed mat or use an alternate concrete melt-through. Beneficial benefit.

material to ensure melt-through does not occur.

102 Construct a building to be connected Reduced probability of CONT01 $1.2M $1.2M $717K $1.1M $1.7M >$10M Expert Panel Not Cost- Cost will exceed to primary/secondary containment containment over-pressurization. Beneficial benefit.

and maintained at a vacuum.

104 Improve leak detection procedures. Increased piping surveillance to LOCA05 $685K $1.2M $620K $1.1M $1.5M >$2M Expert Panel Not Cost- Cost will exceed identify leaks prior to complete Beneficial benefit.

failure. Improved leak detection would reduce LOCA frequency.

107 Install a redundant containment spray Increased containment heat CONT01 $1.2M $1.2M $717K $1.1M $1.7M >$2M Expert Panel Not Cost- Cost will exceed system. removal ability. Beneficial benefit.

108 Install an independent power supply Reduced hydrogen detonation H2BURN $10K $15K $9K $13K $20K >$100K Expert Panel Not Cost-to the hydrogen control system using potential. Beneficial either new batteries, a non-safety grade portable generator, existing station batteries, or existing AC/DC independent power supplies, such as the security system diesel.

109 Install a passive hydrogen control Reduced hydrogen detonation H2BURN $10K $15K $9K $13K $20K >$100M Expert Panel Not Cost- Cost will exceed system. potential. Beneficial benefit.

110 Erect a barrier that would provide Reduced probability of MAB >$10M Expert Panel Not Cost- Cost will exceed enhanced protection of the containment failure. Beneficial benefit.

containment walls (shell) from ejected core debris following a core melt scenario at high pressure.

111 Install additional pressure or leak Reduced ISLOCA frequency. ISLOCA $123K $179K $111K $154K $259K >$500K Expert Panel Not Cost- Cost will exceed monitoring instruments for detection Beneficial benefit.

of ISLOCAs.

112 Add redundant and diverse limit Reduced frequency of CONT02 $1K $1K $1K $1K $2K >$1M Expert Panel Not Cost- Cost will exceed switches to each containment containment isolation failure and Beneficial benefit.

isolation valve. ISLOCAs.

113 Increase leak testing of valves in Reduced ISLOCA frequency. ISLOCA $123K $179K $111K $154K $259K >$1M Expert Panel Not Cost- Cost will exceed ISLOCA paths. Beneficial benefit.

114 Install self-actuating containment Reduced frequency of isolation CONT02 $1K $1K $1K $1K $2K >$500K Expert Panel Not Cost- Cost will exceed isolation valves. failure. Beneficial benefit.

115 Locate residual heat removal (RHR) Reduced frequency of ISLOCA ISLOCA $123K $179K $111K $154K $259K >$1M Expert Panel Not Cost- Cost will exceed inside containment outside containment. Beneficial benefit.

116 Ensure ISLOCA releases are Scrubbed ISLOCA releases. ISLOCA $123K $179K $111K $154K $259K >$1M Expert Panel Not Cost- Cost would exceed scrubbed. One method is to plug Beneficial benefit. Current plant drains in potential break areas so that design requires break point will be covered with drains to be open.

water. Analysis and license changes required to implement are included in the cost estimate.

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Attachment F Severe Accident Mitigation Alternatives Table 8-1. Callaway Plant Sensitivity Evaluation (Continued)

Callaway Benefit at Benefit at Benefit SAMA SAMA 3% Disc Realistic Benefit at 95%

Number Potential Improvement Discussion Case Benefit Rate Disc Rate at 33yrs CDF Cost Cost Basis Evaluation Basis for Evaluation 119 Institute a maintenance practice to Reduced frequency of steam NOSGTR $1.2M $1.7M $1.0M $1.5M $2.4M >$3M Expert Panel Not Cost- Cost will exceed perform a 100% inspection of steam generator tube ruptures. Beneficial benefit.

generator tubes during each refueling outage.

121 Increase the pressure capacity of the Eliminates release pathway to NOSGTR $1.2M $1.7M $1.0M $1.5M $2.4M >$10M Expert Panel Not Cost- Cost will exceed secondary side so that a steam the environment following a Beneficial benefit.

generator tube rupture would not steam generator tube rupture.

cause the relief valves to lift.

122 Install a redundant spray system to Enhanced depressurization NOSGTR $1.2M $1.7M $1.0M $1.5M $2.4M >$10M Expert Panel Not Cost- Cost will exceed depressurize the primary system capabilities during steam Beneficial benefit.

during a steam generator tube generator tube rupture.

rupture 125 Route the discharge from the main Reduced consequences of a NOSGTR $1.2M $1.7M $1.0M $1.5M $2.4M >$10M Expert Panel Not Cost- Cost will exceed steam safety valves through a steam generator tube rupture. Beneficial benefit.

structure where a water spray would condense the steam and remove most of the fission products.

126 Install a highly reliable (closed loop) Reduced consequences of a NOSGTR $1.2M $1.7M $1.0M $1.5M $2.4M >$10M Expert Panel Not Cost- Cost will exceed steam generator shell-side heat steam generator tube rupture. Beneficial benefit.

removal system that relies on natural circulation and stored water sources 129 Vent main steam safety valves in Reduced consequences of a NOSGTR $1.2M $1.7M $1.0M $1.5M $2.4M >$10M Expert Panel Not Cost- Cost will exceed containment. steam generator tube rupture. Beneficial benefit. Current containment design does not support this modification.

Modifications to containment and associated analysis are included in the cost estimate.

130 Add an independent boron injection Improved availability of boron NOATWS $63K $104K $57K $90K $134K >$1M Expert Panel Not Cost- Cost will exceed system. injection during ATWS. Beneficial benefit.

131 Add a system of relief valves to Improved equipment availability NOATWS $63K $104K $57K $90K $134K >$2M Expert Panel Not Cost- Cost will exceed prevent equipment damage from after an ATWS. Beneficial benefit.

pressure spikes during an ATWS.

133 Install an ATWS sized filtered Increased ability to remove NOATWS $63K $104K $57K $90K $134K >$1M Expert Panel Not Cost- Cost will exceed containment vent to remove decay reactor heat from ATWS events. Beneficial benefit heat.

136 Install motor generator set trip Reduced frequency of core NOATWS $63K $104K $57K $90K $134K >$500K Expert Panel Not Cost- Cost will exceed breakers in control room. damage due to an ATWS. Beneficial benefit.

147 Install digital large break LOCA Reduced probability of a large LOCA05 $689K $1.2M $620K $1.1M $1.5M >$5M Expert Panel Not Cost- Cost will exceed protection system. break LOCA (a leak before Beneficial benefit.

break).

153 Install secondary side guard pipes up Prevents secondary side NOSLB $51K $87K $46K $77K $108K >$1M Expert Panel Not Cost- Cost will exceed to the main steam isolation valves. depressurization should a steam Beneficial benefit.

line break occur upstream of the main steam isolation valves.

Also guards against or prevents consequential multiple steam generator tube ruptures following a main steam line break event.

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Attachment F Severe Accident Mitigation Alternatives Table 8-1. Callaway Plant Sensitivity Evaluation (Continued)

Callaway Benefit at Benefit at Benefit SAMA SAMA 3% Disc Realistic Benefit at 95%

Number Potential Improvement Discussion Case Benefit Rate Disc Rate at 33yrs CDF Cost Cost Basis Evaluation Basis for Evaluation 160 Modifications to lessen impact of Lower impact of flood that <$50K Expert Panel Potentially Relatively minor internal flooding path through Control propagates through the Cost-Beneficial modifications to door Building dumbwaiter. dumbwaiter opening could result in lower flow to the dumbwaiter. Specific benefit could not be calculated but SAMA item is judged to be low cost and therefore potentially cost beneficial.

161 Improvements to PORV performance Decrease in risk due to PORV PORV $18K $32K $16K $28K $39K >$100K Expert Panel Not Cost- Cost will exceed that will lower the probability of failure failing to open. Beneficial benefit.

to open.

162 Install a large volume EDG fuel oil Allows transfer of EDF fuel oil to EDGFUEL $124K $131K $113K $156K $263K $150K Wolf Creek Potentially Wolf Creek estimated tank at an elevation greater than the the EDG day tanks on failure of Cost-Beneficial cost of $150K is less EDG fuel oil day tanks. the fuel oil transfer pumps. than the potential benefit.

163 Improve feedwater check valve Lower risk due to failures in FW02 $127K $218K $115K $191K $270K >$500K Expert Panel Not Cost- Cost will exceed reliability to reduce probability of which feedwater check valves fail Beneficial benefit.

failure to open. to open and allow feeding of the steam generators.

164 Provide the capability to power the Provide backup to ESW in SW03 $1191K $307K $172K $267K $403K >$500K Expert Panel Not Cost- Cost will exceed normal service water pumps from conditions with power only Beneficial benefit.

AEPS. available from AEPS.

171 Increase the size of the RWST or Ensure a supply of makeup LOCA04 $13K $23K $12K $20K $27K >$100K Expert Panel Not Cost- Cost will exceed otherwise improve the availability of water is available from the Beneficial benefit.

the RWST RWST.

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Attachment F Severe Accident Mitigation Alternatives

9.0 CONCLUSION

S As a result of this analysis, the SAMAs identified in Table 9-1 have been identified as potentially cost beneficial. Since these potential improvements could result in a reduction in public risk, these SAMAs will be entered into the Callaway long-range plan development process for further consideration.

Table 9-1. Callaway Plant Potentially Cost Beneficial SAMAs Callaway SAMA Number Potential Improvement Discussion Additional Discussion 29 Provide capability for alternate Improved injection Currently being evaluated injection via diesel-driven fire capability. by plant improvement pump. program. Would use unborated water and portable pump (fire truck).

Calculation of specific benefit of this SAMA was not performed since it is judged to be potentially low cost. Evaluation will consider impacts of injection of non-borated water.

160 Modifications to lessen impact of Lower impact of flood that internal flooding path through propagates through the Control Building dumbwaiter. dumbwaiter 162 Install a large volume EDG fuel Allows transfer of EDG fuel oil tank at an elevation greater oil to the EDG day tanks than the EDG fuel oil day tanks. on failure of the fuel oil transfer pumps.

10.0 REFERENCES

1. U. S. NRC Generic Letter 88-20, Individual Plant Examination for Severe Accident Vulnerabilities - 10 CFR 50.54(f), November 23, 1988.

2. A21.0027, Summary Report on the 4B Interim Update of the Callaway PRA, March 2011.

3. Electric Power Research Institute TR-105396, PSA Applications Guide, August 1995.

4. Westinghouse WCAP-15603, WOG2000 Reactor Coolant Pump Seal Leakage Model for Westinghouse PWRs, Revision 1-A, June 2003.

5. U. S. NRC NUREG/CR-5496, Evaluation of Loss of Offsite Power Events at Nuclear Power Plants: 1980-1996, November 1998.

6. Westinghouse WCAP-15210, Transient Initiating Event Operating History Database for U.S.

Westinghouse NSSS Plants (1987-1997), Revision 1, November 1999.

7. U. S. NRC NUREG/CR-INEEL/EXT-04-02326, Evaluation of Loss of Offsite Power Events at Nuclear Power Plants: 1986 - 2003 (Draft), Draft.

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Attachment F Severe Accident Mitigation Alternatives

8. U. S. NRC NUREG-1407, Procedural and submittal Guidance for the Individual Plant Examination of external Events (IPEEE) for Severe Accident Vulnerabilities, June 1991.

9. U. S. NRC Title 10 Code of Federal Regulations Part 50, Appendix R, Fire Protection Program for Nuclear Power Facilities Operating Prior to January 1, 1979.

10. U. S. NRC NUREG/CR-2300, PRA Procedures Guide, January 1983.

11. U. S. NRC NUREG-1465, Accident Source Terms for Light-Water Nuclear Power Plants.

12. U. S. NRC NUREG/CR-6109, The Probability of Containment Failure by Direct Containment Heating In Surry, May 1995.

13. U. S. NRC NUREG/CR-6338, Resolution of Direct Containment Heating Issue for All Westinghouse Plants with Large Dry Containments or Subatmospheric Containments, February 1996.

14. Westinghouse WCAP-15955, Steam Generator Tube Rupture PSA Notebook, December 2002.

15. U. S. NRC NUREG/BR-0184, Regulatory Analysis Technical Evaluation Handbook, 1997.

16. Westinghouse WCAP-15603, WOG2000 Reactor Coolant Pump Seal Leakage Model for Westinghouse PWRs, Revision 0, December 2000.

17. INEEL, Reliability Study: Westinghouse Reactor Protection System, 1984-1995, NUREG/CR-5500, Vol. 2, INEEL/EXT-97-00740, April 1999.

18. U. S. NRC NUREG-1715, Volume 4, Component Performance Study - Motor Operated Valves, 1987 - 1998, September 2001.

19. Nuclear Energy Institute NEI 05-01, Severe Accident Mitigation Alternatives (SAMA)

Analysis Guidance Document, November 2005.

20. Office of Management and Budget, Regulator Analysis, Circular No. A-4, September 17, 2003.

21. U. S. NRC NUREG/BR-0058, Revision 4, Regulatory Analysis Guidelines of the U. S.

Nuclear Regulatory Commission, September 2004.

22. U. S. NRC NUREG/CR-6613, Code Manual for MACCS2, Users Guide, May 1998.

23. U. S. NRC, Regulatory Guide 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis, Revision 1, November 2002.

24. ERIN Engineering and Research, Inc., Callaway Level 2 Analysis, Rev. 1, April 2011.

25. Erin Engineering and Research, Inc., Level 3 PRA Consequence Analysis (MACCS2 Model) for Callaway Sever Accident Mitigation Alternative (SAMA) Evaluation, February 2011.

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Attachment F Severe Accident Mitigation Alternatives

26. U. S. NRC NUREG/CR-6525, SECPOP2000: Sector Population, Land Fraction, and Economic Estimation Program, Revision 1, August 2003.

27. American Society of Mechanical Engineers, ASME RA-Sb-2005, Addenda to ASME RA-S-2002, Standard for Probabilistic Risk Assessment for Nuclear Power Plant Applications, December 30, 2005.

28. Docket Number 50-483, Callaway Plant Response to Generic Letter 88-20, Individual Plant Examination (IPE), September 1992.

29. Docket Number 50-483, Callaway Plant Response to Generic Letter 88-20, Supplemental No.4, Individual Plant Examination of External Events (IPEEE), June 1995.

11.0 ANNEX - PRA RUNS FOR SELECTED SAMA CASES This annex describes each of the SAMA evaluation cases. An evaluation case is an evaluation of plant risk using a plant PRA model that considers implementation of the evaluated SAMA.

The case-specific plant configuration is defined as the plant in its baseline configuration with the model modified to represent the plant after the implementation of a particular SAMA. As indicated in the main report, these model changes were performed in a manner expected to bound the change in risk that would actually be expected if the SAMA were implemented. This approach was taken because the actual designs for the SAMAs have not been developed.

Each analysis case is described in the following pages. Each case description contains a description of the physical change that the case represents along with a description of the SAMAs that are being evaluated by this specific case.

The PDS frequencies calculated as a result of the PRA model quantification for each SAMA case is presented in Table 11-1.

NOATWS This case is used to determine the benefit of eliminating all Anticipated Transient Without Scram (ATWS) events. For the purposes of the analysis, a single bounding analysis was performed which assumed that ATWS events do not occur.

NOSGTR This case is used to determine the benefit of eliminating all Steam Generator Tube Rupture (SGTR) events. This allows evaluation of various possible improvements that could reduce the risk associated with SGTR events. For the purposes of this analysis, a single bounding analysis was performed which assumed that SGTR events do not occur.

INSTAIR This case is used to determine the benefit of replacing the air compressors. For the purposes of the analysis, a single bounding condition was performed, which assumed the station air systems do not fail.

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Attachment F Severe Accident Mitigation Alternatives NOLOSP This case is used to determine the benefit of eliminating all Loss of Offsite Power (LOSP) events, both as the initiating event and subsequent to a different initiating event. This allows evaluation of various possible improvements that could reduce the risk associated with LOSP events. For the purposes of the analysis, a single bounding analysis was performed which assumed that LOSP events do not occur.

CCW01 This case is used to determine the benefit of improvement to the CCW system by assuming that CCW pumps do not fail.

FW01 Eliminate loss of feedwater initiating events. This case is used to determine the benefit of improvements to the feedwater and feedwater control systems.

NOSLB This case is used to determine the benefit of installing secondary side guard pipes to the Main Steam Isolation Valves (MSIVs). This would prevent secondary side depressurization should a Steam Line Break (SLB) occur upstream of the MSIVs. For the purposes of the analysis, a single bounding analysis was performed which assumed that no SLB inside containment events occur.

CHG01 Assume the charging pumps are not dependent on cooling water. This case is used to determine the benefit of removing the charging pumps dependency on cooling water.

SW01 Assume the service water pumps are not dependent on DC power. This case is used to determine the benefit of enhancing the DC control power to the service water pumps.

NOSBO This case is used to determine the benefit of eliminating all Station Blackout (SBO) events. This allows evaluation of possible improvements related to SBO sequences. For the purpose of the analysis, a single bounding analysis is performed that assumes the emergency AC power supplies do not fail.

LOCA05 Assume that piping system LOCAs do not occur. This case is used to determine the benefit of eliminating all LOCA events related to piping failure (no change to non-piping failure is considered).

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Attachment F Severe Accident Mitigation Alternatives NOSLOCA Assume small LOCA events do not occur. This case is used to determine the benefit of eliminating all small LOCA events.

H2BURN Assume hydrogen burns and detonations do not occur. This case is used to determine the benefit of eliminating all hydrogen ignition and burns.

RCPLOCA This case is used to determine the benefit of eliminating all Reactor Coolant Pump (RCP) seal loss of coolant accident (LOCA) events. This allows evaluation of various possible improvements that could reduce the risk associated with RCP seal LOCA and other small LOCA events.

LOCA02 This case is used to determine the benefit of no failures of high pressure injection/recirculation systems. This allows evaluation of various possible improvements that could reduce the risk associated with high pressure injection/recirculation failures.

LOCA12 This case is used to determine the benefit of no failures of high pressure injection/recirculation pumps. This allows evaluation of various possible improvements that could reduce the risk associated with high pressure injection/recirculation pump failures.

CONT02 Eliminate all containment isolation failures.

LOCA04 Assume RWST does not run out of water.

CONT01 Eliminate all containment overpressure failures.

LOCA03 This case is used to determine the benefit of no failures of low pressure injection/recirculation pumps. This allows evaluation of various possible improvements that could reduce the risk associated with low pressure injection/recirculation pump failures.

SW02 This case is used to determine the benefit of no failures service water pumps.

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Attachment F Severe Accident Mitigation Alternatives DC01 Eliminates the TDAFW pump dependency on DC power.

CCW02 Sets all CCW pumps and SW pumps to 0.0 to evaluate the benefit of backup cooling water supplies.

ISLOCA Eliminate all intra-system LOCA failures.

LOSP1 Used to evaluate the benefit of providing tornado protection for the AEPS diesel generators.

DEPRESS Evaluate additional means of depressurization by making depressurization always successful.

LOCA06 Assume that Large LOCAs do not occur. This case is used to determine the benefit of eliminating all risk due to Large LOCA events.

HVAC Eliminates various HVAC dependencies.

FB01 Used to evaluate modifying the PORVs such that only one PORV is required for Feed and Bleed.

PORV Used to evaluate improvements that lower the probability of PORVs failing to open.

EDGFUEL Used to evaluate the addition of a gravity feed EDG fuel oil tank.

FW02 Used to evaluate improvements that lower the probability of feedwater check valves failing to open.

SW03 Used to evaluate adding the ability to power the normal service water pumps from the AEPS.

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Attachment F Severe Accident Mitigation Alternatives HVAC02 Used to evaluate adding additional UHS cooling tower electrical room HVAC.

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Attachment F Severe Accident Mitigation Alternatives Table 11-1. Callaway Plant Release Category Frequency Results Obtained From SAMA Cases RELEASE CATEGORY BASE NOATWS INSTAIR NOLOSP NOSLOCA CCW01 FW01 NOSGTR NOSLB CHG01 LERF-IS 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 LERF-CI 1.658E-10 1.411E-10 1.658E-10 1.422E-10 6.210E-11 1.567E-10 1.658E-10 1.658E-10 1.610E-10 1.658E-10 LERF-CF 1.125E-08 1.103E-08 1.124E-08 7.372E-09 5.378E-09 1.071E-08 1.115E-08 1.125E-08 1.116E-08 1.123E-08 LERF-SG 2.331E-06 2.306E-06 2.330E-06 2.331E-06 2.331E-06 2.331E-06 2.331E-06 0.000E+00 2.331E-06 2.331E-06 LERF-ITR 2.170E-07 1.845E-07 2.167E-07 1.309E-07 2.072E-07 2.170E-07 2.052E-07 0.000E+00 1.936E-07 2.169E-07 LATE-BMT 2.551E-06 2.268E-06 2.547E-06 1.254E-07 2.029E-06 2.507E-06 2.448E-06 2.551E-06 2.515E-06 2.467E-06 LATE-COP 3.185E-06 3.185E-06 3.185E-06 1.796E-08 3.170E-06 3.185E-06 3.185E-06 3.185E-06 3.185E-06 3.185E-06 SERF 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 INTACT 8.080E-06 8.075E-06 8.080E-06 7.065E-06 2.553E-06 7.573E-06 7.983E-06 8.080E-06 7.773E-06 8.137E-06 TOTAL 1.655E-05 1.620E-05 1.654E-05 9.851E-06 1.047E-05 1.600E-05 1.634E-05 1.400E-05 1.618E-05 1.652E-05 Table 11-1. Callaway Plant Release Category Frequency Results Obtained From SAMA Cases (Continued)

RELEASE CATEGORY SW01 NOSBO LOCA05 H2BURN RCPLOCA LOCA 12 CONT02 LOCA04 LOCA03 CONT01 LERF-IS 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 LERF-CI 1.658E-10 1.658E-10 6.210E-11 1.658E-10 1.567E-10 1.658E-10 0.000E+00 1.658E-10 1.658E-10 1.658E-10 LERF-CF 1.124E-08 1.030E-08 5.018E-09 4.102E-12 1.048E-08 1.099E-08 1.125E-08 1.114E-08 1.089E-08 1.125E-08 LERF-SG 2.331E-06 2.329E-06 2.331E-06 2.331E-06 2.331E-06 2.331E-06 2.331E-06 2.331E-06 2.298E-06 2.331E-06 LERF-ITR 2.170E-07 1.443E-07 2.072E-07 2.170E-07 2.170E-07 2.165E-07 2.170E-07 2.170E-07 2.169E-07 2.170E-07 LATE-BMT 2.553E-06 1.611E-06 2.009E-06 2.551E-06 2.475E-06 1.893E-06 2.551E-06 2.441E-06 2.007E-06 2.551E-06 LATE-COP 3.181E-06 2.426E-06 3.170E-06 3.170E-06 3.173E-06 3.182E-06 3.185E-06 3.185E-06 3.185E-06 0.000E+00 SERF 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 INTACT 8.080E-06 7.883E-06 2.170E-06 8.080E-06 7.301E-06 8.329E-06 8.080E-06 8.080E-06 8.180E-06 8.080E-06 TOTAL 1.655E-05 1.458E-05 1.007E-05 1.652E-05 1.568E-05 1.614E-05 1.655E-05 1.644E-05 1.607E-05 1.336E-05 Callaway Plant Unit 1 Environmental Report for License Renewal F-110

Attachment F Severe Accident Mitigation Alternatives Table 11-1. Callaway Plant Release Category Frequency Results Obtained From SAMA Cases (Continued)

RELEASE CATEGORY BREAKER DC01 SW02 CCW02 CST01 ISLOCA LOSP1 DEPRESS LOCA06 HVAC LERF-IS 1.730E-07 1.730E-07 1.730E-07 1.730E-07 1.730E-07 0.000E+00 1.730E-07 1.730E-07 1.730E-07 1.730E-07 LERF-CI 1.666E-10 1.658E-10 1.514E-10 1.422E-10 1.650E-10 1.658E-10 1.666E-10 1.658E-10 1.658E-10 1.658E-10 LERF-CF 1.129E-08 1.124E-08 9.548E-09 8.906E-09 1.112E-08 1.125E-08 1.113E-08 1.122E-08 1.109E-08 1.099E-08 LERF-SG 2.328E-06 2.331E-06 2.331E-06 2.331E-06 2.331E-06 2.331E-06 2.331E-06 2.331E-06 2.331E-06 2.329E-06 LERF-ITR 2.093E-07 2.170E-07 2.110E-07 2.108E-07 2.169E-07 2.170E-07 1.814E-07 2.160E-07 2.169E-07 1.944E-07 LATE-BMT 2.047E-06 2.551E-06 2.417E-06 1.864E-06 2.022E-06 2.551E-06 2.039E-06 2.508E-06 2.020E-06 1.657E-06 LATE-COP 3.210E-06 3.185E-06 1.455E-06 1.455E-06 3.185E-06 3.185E-06 2.991E-06 3.166E-06 3.185E-06 2.917E-06 SERF 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 INTACT 8.180E-06 8.080E-06 7.951E-06 7.836E-06 8.471E-06 8.080E-06 8.431E-06 8.069E-06 8.431E-06 8.312E-06 TOTAL 1.616E-05 1.655E-05 1.455E-05 1.388E-05 1.641E-05 1.638E-05 1.616E-05 1.647E-05 1.637E-05 1.559E-05 Table 11-1. Callaway Plant Release Category Frequency Results Obtained From SAMA Cases (Continued)

RELEASE CATEGORY FB01 PORV EDGFUEL FW02 SW03 HVAC02 LERF-IS 1.730E-07 1.730E-07 1.730E-10 1.730E-07 1.730E-07 1.730E-07 LERF-CI 1.658E-10 1.658E-10 1.658E-10 1.658E-10 1.514E-10 1.658E-10 LERF-CF 1.094E-08 1.112E-08 1.124E-08 1.047E-08 1.031E-08 1.096E-08 LERF-SG 2.326E-06 2.331E-06 2.331E-06 2.324E-06 2.331E-06 2.331E-06 LERF-ITR 1.796E-07 2.169E-07 2.169E-07 1.659E-07 2.141E-07 2.169E-07 LATE-BMT 2.006E-06 2.022E-06 2.544E-06 1.983E-06 2.428E-06 1.990E-06 LATE-COP 3.185E-06 3.185E-06 3.182E-06 3.185E-06 2.557E-06 2.823E-06 SERF 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 INTACT 8.146E-06 8.471E-06 8.078E-06 7.796E-06 7.907E-06 8.461E-06 TOTAL 1.603E-05 1.641E-05 1.636E-05 1.564E-05 1.562E-05 1.601E-05 Callaway Plant Unit 1 Environmental Report for License Renewal F-111