ML12334A797

Official Exhibit - NYS000281-00-BD01 - Environmental Report, Arkansas Nuclear One - Unit 2, Excerpted: Attachment E - Severe Accident Mitigation Analysis (Arkansas Er)

ML12334A797
Person / Time
Site:	Indian Point
Issue date:	12/21/2011
From:	Entergy Operations
To:	Atomic Safety and Licensing Board Panel
SECY RAS
References
RAS 21597, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01
Download: ML12334A797 (70)

Text

NYS000281 United States Nuclear Regulatory Commission Official Hearing Exhibit Submitted: December 21, 2011 Entergy Nuclear Operations, Inc. EXCERPT In the Matter of:

(Indian Point Nuclear Generating Units 2 and 3)

ASLBP #: 07-858-03-LR-BD01 Docket #: 05000247 l 05000286 Exhibit #: NYS000281-00-BD01 Identified: 10/15/2012 Admitted: 10/15/2012 Withdrawn:

Rejected: Stricken:

Other:

Attachment E Severe Accident Mitigation Alternatives Analysis Attachment E contains the following sections:

E.1 - Melcor Accident Consequences Code System Modeling E.2 - Evaluation of SAMA Candidates D-1

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage E.1 MELCOR ACCIDENT CONSEQUENCES CODE SYSTEM MODELING E.1.1 Introduction The following sections describe the assumptions made and the results of modeling performed to assess the risks and consequences of severe accidents at ANO-2.

The severe accident consequence analysis was carried out with the Melcor Accident Consequence Code System (Reference E.1-1). MACCS2 simulates the impact of severe accidents at nuclear power plants on the surrounding environment. The principal phenomena considered in MACCS2 are atmospheric transport, mitigating actions based on dose projection, dose accumulation by a number of pathways including food and water ingestion, early and latent health effects, and economic costs.

E.1.2 Input The input data required by MACCS2 are outlined below.

E.1.2.1 Core Inventory The core inventory in Table E.1-1 is for ANO-2 at a power level of 3026 megawatts-thermal (Reference E.1-11). These values were obtained by adjusting the end-of-cycle values for a 3,412 megawatts-thermal pressurized water reactor by a linear scaling factor of 0.887 (Reference E.1-1).

E.1.2.2 Source Terms The source term input data to MACCS2 were the severe accident source terms presented in the probabilistic risk assessment in the ANO-2 IPE (Reference E.1-2). This document defines the releases in terms of release modes and demonstrates the method of calculating releases.

There are 51 release modes: 20 with early containment failure, 25 with late containment failure, and 6 with containment bypass as the failure mode. Table E.1-2 lists the input release fractions for each MACCS2 nuclide group together with the source category frequencies calculated in the probabilistic risk assessment. For all modes the Ruthenium, Lanthanum, Cerium, and Barium fractions of the usual MACCS2 species were set to zero, as they were not reported in the IPE submittal. Assignment of the radionuclides in Table E.1-1 to these nuclide groups was the same as that of the standard MACCS2 input. Other related source term data, such as release durations and energies, were evaluated by comparison with similar releases reported in the NUREG-1150 studies for the Surry plant (Reference E.1-3).

The amount of each radionuclide released to the atmosphere for each accident sequence or release category was obtained by multiplying the core inventory at the time of the hypothetical accident (Table E.1-1) by the release fraction (Table E.1-2) assigned to each of the nuclide groups.

The off-site consequences were summed for the release modes weighted by the annual frequency to obtain the total annual accident risk for the baseline and for each of the SAMA Environmental Report Page E-1 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage candidates evaluated. (This summation calculation was performed outside of the MACCS2 code as part of the SAMA cost benefit analyses.)

E.1.2.3 Meteorological Data The MACCS2 input included a full year (1996) of consecutive hourly values of wind speed, wind direction and stability class recorded at the site meteorological tower. Since the site did not record precipitation data for 1996, precipitation data was obtained for the nearest available recording site from the National Climatic Data Center of the National Oceanic and Atmospheric Administration of the U.S. Dept. of Commerce. This was the hourly precipitation recorded for 1996 at Clarksville 6 NE COOP STATION 03157, located at 35º 32' N, 93º 24' W (about 20 miles northwest of the ANO-2 site) (Reference E.1-4). The seasonal mixing heights for this area of Arkansas were taken from maps of mixing heights for the United States.

This weather data is representative and typical for the following reasons:

(a) The population density is relatively low near the plant. This, together with the weather sampling scheme used by MACCS2, tends to diminish the importance of year-to-year meteorological variations, and (b) The SAMA analysis is concerned with differences, subtracting the SAMA effect from the baseline effect. Because of this differential approach, the effect of year-to-year weather variations on differential benefits is of second order importance, and does not significantly affect the results.

MACCS2 calculations examine a representative subset of the 8,760 hourly observations contained in one years data set (typically about 150 sequences). The representative subset is selected by sampling the weather sequences after sorting them into weather bins defined by wind speed, atmospheric stability, and rain conditions at various distances from the site.

E.1.2.4 Population Distribution The predicted population around the site for the year 2040 was distributed by location in a grid consisting of sixteen directional sectors, the first of which is centered on due north, the second on 22.5 degrees east of north, and so on. A summary of the population distribution is shown in Table E.1-3. The direction sectors were divided into 15 radial intervals extending out to 50 miles. The habitable land fraction for each grid element was calculated from land fraction data within a 50-mile radius of the plant.

The basis for the extrapolated population data is the 2000 census (Reference E.1-10) and the estimated 1998 transient population. The census data was obtained from the University of Arkansas/Little Rock Institute for Economic Advancement (the official repository of the Arkansas census data). The data was processed by first determining if the center (centroid) of a census block occurred within a grid sub-sector. If so, the population associated with that census block was assigned to that particular sub-sector. Since the centroid for one of the census blocks occurs with 0.65 miles of the plant, this standard practice makes it appear that 28 people reside Environmental Report Page E-2 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage with the exclusion area boundary. Actually, no one resides with the exclusion area boundary, and this is just an artifact of the population distribution process, and is considered conservative.

Before extrapolation to 2040, the 2000 population was adjusted to account for transient population. The transient population in the emergency planning zone (exclusion boundary of 0.65 miles to 10 miles) was estimated and added to the resident population. The area is a popular recreational zone and it was considered appropriate to add these individuals for dose estimation purposes (even though it results in an overestimation of the economic costs for non-farm property in this area). A similar approach was used for the ANO-1 SAMA (Reference E.1-9). For the ANO-1 analysis, the number of cars into each recreational area was taken from the Site Emergency Plan. From this source, the number of individuals in each sub-sector was estimated for 1980. For the ANO-2 analysis, the ANO-1 estimates were extrapolated to 2000 by using the ratio of Arkansas population in 2000 to Arkansas population in 1980 as a scale factor.

The 2000 census data (Reference E.1-10) and the 1990 census data (Reference E.1-5) were then used to project the future rosette section populations for the year 2040. A 50-mile radius growth factor was calculated by dividing the 50-mile radius population in 2000 by the 1990 population. This resulted in a growth factor of 27.34% per decade. The section population projection for 2040 was then estimated by extrapolating the 2000 section population according to this growth factor.

Using the 2040 projected population yields conservative results, since a severe accident and radiological release can only occur between now and the end of the period of extended operation (2038). The population in 2038 is likely to be less than that projected for 2040. Since economic impact is a function of population, the actual economic impact would be less than the estimated economic impact.

Since the population projections include transient population estimates in the 10-mile zone around the plant, the data is slightly larger in this zone than may be shown elsewhere in tables of population projections for the region.

E.1.2.5 Emergency Response The evacuation modeling employed for the severe accident mitigation alternatives analyses was based on the site-specific evacuation plan (Reference E.1-7). The plan addresses evacuation of the population within the plume exposure emergency planning zone, a 10-mile radius centered on the plant site.

The emergency evacuation model was modeled as a single radial evacuation zone extending out 10 miles from the plant. In the plan, it is stated that 15% of the people will start moving 30 minutes after the alarm rings, 80% of people will start moving 90 minutes after the alarm rings, and 5% of the people will start moving 120 minutes after the alarm rings. The clear times for each of the four emergency planning zones were estimated by using weighted averages of the plan clear times for four different time periods, weekday, night, weekend, and adverse weekday.

The average evacuation speed for the emergency zone was then estimated using the population-weighted average of the evacuation speed of each planning zone.

Environmental Report Page E-3 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage Because of the recreational nature of the area immediately surrounding the plant, the population in the emergency zone was augmented by adding the transient population to the census-based resident population. An average evacuation start time delay of 4950 seconds and an average radial evacuation speed of 1.2 m/s were estimated in the above manner. Due to the uncertainty of the population proportionality assumption, the value of 1.0 m/s (used in the ANO-1 SAMA analysis, Reference E.1-9) was used for the evacuation speed. A sensitivity analysis using the 1.2 m/s evacuation speed showed a drop of almost 9% in the population dose, demonstrating that the base case parameter generates conservative results.

For this analysis it was conservatively assumed that people beyond 10 miles would continue their normal activities unless the following predicted radiation dose levels are exceeded. At locations for which 50 rem whole body effective dose equivalent in one week is predicted, it was assumed that relocation would take place after half a day. If 25 rem whole body dose equivalent in one week is predicted, relocation of individuals in those sectors was assumed to take place after one day.

A sensitivity analysis was performed in which it was assumed that only 90% of the people within the emergency planning zone participated in the evacuation. The remaining 10% were assumed to be unable or unwilling to evacuate and were assumed to go about their normal activities. The results were not significantly different from the complete evacuation case. While the population doses increased and the evacuation costs decreased, the overall population exposure and accident mitigation costs are governed mainly by the long term effects over the whole 50-mile zone, and so the net changes were small.

Another sensitivity analysis was performed to assess the importance of the warning and release delay times. Two hours were subtracted from the base case alarm and delay times, while the late release start time was decreased from 150,000 seconds to 86,400 seconds to effect a comparable change. The results show that the duration has a small impact on the overall population dose since evacuees spend more time in the last phase of evacuation when there are more mechanisms for sheltering. The results demonstrate that the base case parameters generate conservative results.

The long-term phase was assumed to begin after one week and extend for five years.

Long-term relocation was assumed to be triggered by a 4 rem whole body effective dose equivalent. Long-term protective measures were assumed to be based on generic protective action guideline levels for actions such as decontamination, temporary relocation, contaminated crops, and milk condemnation, and farmland production prohibition.

E.1.2.6 Economic Data Land use statistics including farmland values, farm product values, dairy production, and growing season information were provided on a countywide basis within 50 miles.

The values used for these parameters were the same as those used for the ANO-1 analysis (Reference E.1-9). This data was taken from the computer program SECPOP90 (Reference E.1-5), which contains a database extracted from Bureau of the Census PL 94-171 (block level census) CD-ROMS (Reference E.1-6), the 1992 Census of Agriculture CD ROM Series 1B, the Environmental Report Page E-4 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage 1994 U.S. Census County and City Data Book CD-ROM, the 1993 and 1994 Statistical Abstract of the United States, and other minor sources. The reference contains details on how the database was created and checked. The regional economic values were updated to 2002 using the consumer price indices for 1997 and 2002 (Reference E.1-8).

Economic consequences were estimated by summing the following costs:

x Costs of evacuation, x Costs for temporary relocation (food, lodging, lost income),

x Costs of decontaminating land and buildings, x Lost return-on-investments from properties that are temporarily interdicted to allow contamination to be decreased by decay of nuclides, x Costs of repairing temporarily interdicted property, x Value of crops destroyed or not grown because they were contaminated by direct deposition or would be contaminated by root uptake, and x Value of farmland and of individual, public, and non-farm commercial property that is condemned.

Table E.1-4 lists the values of the economic parameters used in MACCS2.

Costs associated with damage to the reactor, the purchase of replacement power, medical care, life-shortening, and litigation are not estimated by MACCS2.

E.1.3 Results Using the preceding input data, MACCS2 was used to estimate the following:

x The downwind transport, dispersion, and deposition of the radioactive materials released to the atmosphere from the failed reactor containment.

x The short-term and long-term radiation doses received by exposed populations via direct (cloud shine, plume inhalation, ground shine, and re-suspension inhalation) and indirect (ingestion) pathways.

x The mitigation of those doses by protective actions (evacuation, sheltering, and post-accident relocation of people; disposal of milk, meat, and crops; and decontamination, temporary interdiction, or condemnation of land and buildings).

Environmental Report Page E-5 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage x The early fatalities and injuries expected to occur within one year of the accident (early health effects) and the delayed (latent) cancer fatalities and injuries expected to occur over the lifetime of the exposed individuals.

x The off-site costs of short-term emergency response actions (evacuation, sheltering, and relocation), of crop and milk disposal, and of the decontamination, temporary interdiction, or condemnation of land and buildings.

The consequences estimated with the MACCS2 model in terms of the population dose and off-site economic costs for the base case are shown in Table E.1-5. These factors were used to estimate risk by multiplying the frequencies by the consequences. The resultant risk was then expressed as the magnitude of consequences expected per unit time. Table E.1-6 shows the risk measures for the base case and the three evacuation-model sensitivity cases (1.2 m/s evacuation speed, 90% evacuation and 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> shorter duration). These were obtained by summing the frequencies multiplied by the consequences over the entire range of distributions.

Because the probabilities are on a per reactor-year basis, the averages shown are also on a per reactor-year basis.

Environmental Report Page E-6 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage Table E.1-1, ANO-2 Core Inventory 1 Core inventory Core inventory Nuclide (becquerels) Nuclide (becquerels)

Cobalt-58 2.86E+16 Tellurium-131M 4.15E+17 Cobalt-60 2.19E+16 Tellurium-132 4.13E+18 Krypton-85 2.20E+16 Iodine-131 2.84E+18 Krypton-85M 1.03E+18 Iodine-132 4.19E+18 Krypton-87 1.88E+18 Iodine-133 6.01E+18 Krypton-88 2.54E+18 Iodine-134 6.60E+18 Rubidium-86 1.67E+15 Iodine-135 5.67E+18 Strontium-89 3.18E+18 Xenon-133 6.02E+18 Strontium-90 1.72E+17 Xenon-135 1.13E+18 Strontium-91 4.09E+18 Cesium-134 3.84E+17 Strontium-92 4.26E+18 Cesium-136 1.17E+17 Yttrium-90 1.84E+17 Cesium-137 2.14E+17 Yttrium-91 3.88E+18 Barium-139 5.57E+18 Yttrium-92 4.28E+18 Barium-140 5.51E+18 Yttrium-93 4.84E+18 Lanthanum-140 5.63E+18 Zirconium-95 4.90E+18 Lanthanum-141 5.17E+18 Zirconium-97 5.11E+18 Lanthanum-142 4.98E+18 Niobium-95 4.63E+18 Cerium-141 5.01E+18 Molybdium-99 5.41E+18 Cerium-143 4.87E+18 Technetium-99M 4.67E+18 Cerium-144 3.02E+18 Ruthenium-103 4.03E+18 Praseodymium-143 4.79E+18 Ruthenium-105 2.62E+18 Neodymium-147 2.14E+18 Ruthenium-106 9.15E+17 Neptunium-239 5.73E+19 Rhodium-105 1.81E+18 Plutonium-238 3.25E+15 Antimony-127 2.47E+17 Plutonium-239 7.33E+14 Antimony-129 8.76E+17 Plutonium-240 9.24E+14 Tellurium-127 2.39E+17 Plutonium-241 1.56E+17 Tellurium-127M 3.16E+16 Americium-241 1.03E+14 Tellurium-129 8.22E+17 Curium-242 3.93E+16 Tellurium-129M 2.17E+17 Curium-244 2.30E+15 1

Reference E.1-1.

Environmental Report Page E-7 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage Table E.1-2, ANO-2 RELEASE FRACTION BY NUCLIDE GROUP 2 Release Xenon/

Frequency 4 Iodine Cesium Tellurium Strontium Mode 3 Krypton A1 4.22E-08 9.20E-01 1.07E-04 9.02E-05 2.99E-05 4.17E-07 A2 8.73E-10 9.20E-01 4.29E-03 3.61E-03 1.20E-03 1.67E-05 B1 1.46E-13 9.20E-01 2.64E-04 2.15E-04 5.99E-05 8.35E-07 B2-L 7.48E-11 9.20E-01 9.96E-03 8.18E-03 2.40E-03 3.34E-05 B2-R 3.95E-12 9.20E-01 9.96E-03 8.18E-03 2.40E-03 3.34E-05 B3-L 7.06E-10 9.20E-01 2.64E-04 2.15E-04 5.99E-05 8.35E-07 B3-R 7.06E-10 9.20E-01 2.64E-04 2.15E-04 5.99E-05 8.35E-07 B4-L 7.32E-09 9.20E-01 9.96E-03 8.18E-03 2.40E-03 3.34E-05 B4-R 1.05E-09 9.20E-01 9.96E-03 8.18E-03 2.40E-03 3.34E-05 B5-L 7.06E-10 9.20E-01 8.82E-04 4.76E-04 1.13E-04 1.57E-06 B5-R 7.06E-10 9.20E-01 8.82E-04 4.76E-04 1.13E-04 1.57E-06 B6-L 3.19E-07 9.20E-01 4.04E-03 2.29E-03 2.03E-04 2.83E-06 B6-R 1.74E-08 9.20E-01 4.04E-03 2.29E-03 2.03E-04 2.83E-06 BP-D3A 3.57E-08 7.44E-01 2.10E-02 2.13E-02 1.51E-02 1.38E-04 BP-D3B 3.57E-08 9.20E-01 2.18E-01 2.21E-01 5.86E-02 1.14E-03 BP-E5A 8.96E-09 8.24E-01 2.12E-02 2.14E-02 1.54E-02 1.38E-04 BP-E5B 8.96E-09 1.00E+00 2.23E-01 2.26E-01 6.56E-02 1.14E-03 BP-E6A 2.98E-09 8.24E-01 2.84E-02 2.60E-02 2.43E-02 1.42E-04 BP-E6B 3.30E-07 1.00E+00 3.89E-01 3.43E-01 2.58E-01 1.16E-03 C1-L 4.71E-09 1.00E+00 6.39E-04 4.85E-04 1.06E-03 8.35E-07 C1-R 9.16E-10 1.00E+00 6.39E-04 4.85E-04 1.06E-03 8.35E-07 C2-L 8.74E-10 1.00E+00 1.03E-02 8.45E-03 4.26E-03 3.34E-05 C2-R 7.13E-10 1.00E+00 1.03E-02 8.45E-03 4.26E-03 3.34E-05 C3-L 3.13E-06 1.00E+00 6.65E-04 5.04E-04 1.06E-03 8.35E-07 C3-R 1.66E-07 1.00E+00 6.65E-04 5.04E-04 1.06E-03 8.35E-07 C4-L 5.46E-07 1.00E+00 2.12E-02 1.63E-02 3.03E-02 3.34E-05 C4-R 2.94E-08 1.00E+00 2.12E-02 1.63E-02 3.03E-02 3.34E-05 C5-L 3.91E-07 1.00E+00 1.26E-03 7.46E-04 1.11E-03 1.57E-06 C5-R 2.12E-08 1.00E+00 1.26E-03 7.46E-04 1.11E-03 1.57E-06 C6-L 5.08E-07 1.00E+00 1.53E-02 1.04E-02 2.81E-02 2.83E-06 2

Reference E.1-2.

3 Release Modes notation:

A, B, C = late releases.

BP = bypass release modes D, E = early releases

-R = containment rupture

-L = containment leak 4

Release Mode frequency per reactor year.

Environmental Report Page E-8 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage Table E.1-2, ANO-2 RELEASE FRACTION BY NUCLIDE GROUP 2 Release Xenon/

Frequency 4 Iodine Cesium Tellurium Strontium Mode 3 Krypton C6-R 2.73E-08 1.00E+00 1.53E-02 1.04E-02 2.81E-02 2.83E-06 D1-L 1.61E-11 9.20E-01 1.41E-03 1.18E-03 3.81E-04 5.31E-06 D1-R 2.62E-09 9.20E-01 5.70E-03 4.79E-03 1.58E-03 2.20E-05 D2-L 3.10E-08 9.20E-01 5.60E-02 4.69E-02 1.52E-02 2.13E-04 D2-R 3.20E-08 9.20E-01 2.28E-01 1.91E-01 6.32E-02 8.80E-04 D3-L 3.49E-08 9.20E-01 5.11E-03 2.73E-03 7.19E-04 1.00E-05 D3-R 5.47E-08 9.41E-01 5.62E-02 3.66E-02 2.36E-02 3.41E-03 D4-L 1.36E-06 9.41E-01 2.02E-02 1.25E-02 6.27E-03 8.30E-04 D4-R 1.36E-06 9.41E-01 7.54E-02 4.70E-02 2.60E-02 3.44E-03 E1-L 7.06E-10 1.00E+00 2.66E-03 2.08E-03 2.73E-03 5.31E-06 E1-R 7.06E-10 1.00E+00 1.10E-02 8.57E-03 8.61E-03 2.20E-05 E2-L 1.04E-09 1.00E+00 5.72E-02 4.78E-02 1.90E-02 2.13E-04 E2-R 1.12E-09 1.00E+00 2.33E-01 1.95E-01 7.63E-02 8.80E-04 E3-L 9.60E-10 1.00E+00 2.75E-03 2.15E-03 2.37E-03 5.31E-06 E3-R 4.19E-08 1.00E+00 1.13E-02 8.84E-03 8.61E-03 2.20E-05 E4-L 2.41E-07 1.00E+00 9.35E-02 7.39E-02 7.11E-02 2.13E-04 E4-R 2.56E-07 1.00E+00 3.85E-01 3.05E-01 2.60E-01 8.80E-04 E5-L 9.36E-09 1.00E+00 6.36E-03 3.63E-03 2.71E-03 1.00E-05 E5-R 1.44E-08 1.00E+00 6.01E-02 3.94E-02 2.87E-02 3.41E-03 E6-L 5.15E-07 1.00E+00 4.77E-02 3.23E-02 4.73E-02 8.30E-04 E6-R 5.19E-07 1.00E+00 1.91E-01 1.30E-01 1.71E-01 3.44E-03 2

Reference E.1-2.

3 Release Modes notation:

A, B, C = late releases.

BP = bypass release modes D, E = early releases

-R = containment rupture

-L = containment leak 4

Release Mode frequency per reactor year.

Environmental Report Page E-9 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage Table E.1-3 ANO-2 Regional Population Distribution (With Emergency Zone Transient Population) 0-10 10-20 20-30 30-40 40-50 Totals Miles Miles Miles Miles Miles N 2318 1341 216 2020 9045 14940 NNE 1999 3311 216 1352 3130 10008 NE 5954 5709 460 2099 4353 18575 ENE 7909 6843 3159 2922 16774 37607 E 15451 9250 4773 9121 28912 67507 ESE 57546 16111 17261 20780 135403 247101 SE 15779 2635 3643 11593 8724 42374 SSE 9913 3667 2751 134 31836 48301 S 7514 7409 3653 421 5092 24089 SSW 3903 6183 5975 673 1999 18733 SW 1146 2838 3251 1483 1231 9949 WSW 986 604 2204 10154 14441 28389 W 940 4918 15688 10391 16246 48183 WNW 4044 4570 10964 22413 10415 52406 NW 5509 29238 5975 1767 3472 45961 NNW 2235 3485 1644 1255 2435 11054 Totals 143146 108112 81833 98578 293508 725177 Environmental Report Page E-10 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage Table E.1-4, MACCS2 Economic Parameters Variable Description Value DPRATE Property depreciation rate (per yr) 0.2 DSRATE Investment rate of return (per yr) 0.12 EVACST Daily cost for a person who has been 43.05 evacuated ($/person-day)

POPCST Population relocation cost ($/person) 7967.12 RELCST Daily cost for a person who is relocated 43.05

($/person-day)

CDFRM0 Cost of farm decontamination for various 896.59 levels of decontamination ($/hectare) 1992.49 CDNFRM Cost of non-farm decontamination per 4781.42 resident person for various levels of 12754.28 decontamination ($/person)

DLBCST Average cost of decontamination labor 55792.80

($/man-year)

VALWF0 Value of farm wealth ($/hectare) 4547.23 VALWNF Value of non-farm wealth ($/person) 126107.80 Environmental Report Page E-11 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage Table E.1-5, Summary of Off-site Consequence Results for Each Release Category Table E.1-5 Release Population Dose Total Economic Cost Category (Sieverts) (Dollars)

A1 250 1.07E+07 A2 2410 3.56E+08 B1 494 2.53E+07 B2-L 3630 6.47E+08 B2-R 3630 6.47E+08 B3-L 494 2.53E+07 B3-R 494 2.53E+07 B4-L 3630 6.47E+08 B4-R 3630 6.47E+08 B5-L 827 6.96E+07 B5-R 827 6.96E+07 B6-L 1890 2.67E+08 B6-R 1890 2.67E+08 BP-D3A 5150 1.18E+09 BP-D3B 12200 3.46E+09 BP-E5A 5180 1.18E+09 BP-E5B 12500 3.48E+09 BP-E6A 5700 1.35E+09 BP-E6B 18900 3.93E+09 C1-L 862 6.96E+07 C1-R 862 6.96E+07 C2-L 3710 6.61E+08 C2-R 3710 6.61E+08 C3-L 888 7.05E+07 C3-R 888 7.05E+07 C4-L 5410 1.05E+09 C4-R 5410 1.05E+09 Environmental Report Page E-12 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage Table E.1-5 Release Population Dose Total Economic Cost Category (Sieverts) (Dollars)

C5-L 1080 1.12E+08 C5-R 1080 1.12E+08 C6-L 4360 7.84E+08 C6-R 4360 7.84E+08 D1-L 1320 1.82E+08 D1-R 2480 4.51E+08 D2-L 7170 2.23E+09 D2-R 14400 3.31E+09 D3-L 2070 3.14E+08 D3-R 6960 1.77E+09 D4-L 4670 9.17E+08 D4-R 7990 1.97E+09 E1-L 1800 2.66E+08 E1-R 3630 6.41E+08 E2-L 7280 2.25E+09 E2-R 14700 3.34E+09 E3-L 1830 2.73E+08 E3-R 3670 6.53E+08 E4-L 8350 2.82E+09 E4-R 22800 3.82E+09 E5-L 2400 3.86E+08 E5-R 7270 1.84E+09 E6-L 6890 1.80E+09 E6-R 13700 3.02E+09 Environmental Report Page E-13 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage Table E.1-6, Risk Measures Population Economic Population Dose Economic Cost Dose (Rem) Cost ($) (% increase (% increase from base case) from base case)

Base Case 1.723 3385 ---- -----

1.2 m/s 1.568 3385 -9.0% 0.0%

evacuation speed 90% evacuation 1.773 3364 2.8% -0.6%

2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> shorter 1.737 3394 0.81% 0.25%

duration E.1.4 References E.1-1 Code Manual for MACCS2, User's Guide, D. Chanin and M. L. Young, Technadyne Engineering Consultants and Sandia National Laboratories for U. S. Nuclear Regulatory Commission and U. S. Department of Energy, SAND97-0594, NUREG/CR-6613, Vol. 1, May 1998.

See also, MELCOR Accident Consequence Code System (MACCS), Model Description, H. N.

Jow, et. al., Sandia National Laboratories for U. S. Nuclear Regulatory Commission, SAND86-1562, Vol. 2, NUREG/CR-4691, February 1990.

Evaluation of Severe Accident Risks: Quantification of Major Input Parameters, MACCS Input, J. L. Sprung, et. al., Sandia National Laboratories for the U. S. Nuclear Regulatory Commission, NUREG/CR-4551, Vol. 2, Rev. 1, Part 7, December 1990.

E.1-2 ANO-2 Probabilistic Risk Assessment (PRA) Individual Plant Examination (IPE)

Submittal, Report Number 94-R-2005-01, March 1994.

E.1-3 Evaluation of Severe Accident Risks: Surry 1 Main Report, NUREG/CR-4551, Vol. 3, Rev. 1, Part 1, Breeding, R. J., et al, October 1990.

E.1-4 1996 Hourly Precipitation Data for Clarksville 6 NE COOP ID 031457, NCDC (National Climatic Data Center, National Oceanic and Atmospheric Administration), Order Num.

6394, May 7, 1999.

E.1-5 SECPOP90: Sector Population, Land Fraction, and Economic Estimation Program, NUREG/CR-6525, Humphreys, S. L., et al, September, 1997.

E.1-6 Census of Population and Housing, 1990: Public Law (P. L.)94-171, Data Technical Documentation, CD - ROM set, BOC (Bureau of the Census, U. S. Dept. of Commerce),

1991.

Environmental Report Page E-14 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage E.1-7 ANO Emergency Plan, Entergy Operations, Inc., Rev. 28, January 15, 2003.

E.1-8 Bureau of Labor Statistics - Consumer Price Index, www.bls.gov/cpi.

E.1-9 Safety Evaluation Report Related to the License Renewal of Arkansas Nuclear One, Unit 1, NUREG-1743, April 2001.

E.1-10 Arkansas Nuclear One 2000 Census Data, letter from B. West, FTN Associates, Ltd. To R. Buckley, Entergy Services, Inc., FTN 6045-062, February 5, 2003.

E.1-11 Arkansas Nuclear One, Unit No. 2 - Issuance of Amendment RE: Increase in Licensed Power Level (Tac. No. MB0789), letter from T. W. Alexion to C. G. Anderson, 2CNA040207, April 24, 2002.

Environmental Report Page E-15 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage E.2 EVALUATION OF SAMA CANDIDATES This section describes the generation of the initial list of potential SAMA candidates, screening methods, and the analysis of the remaining SAMA candidates.

E.2.1 SAMA List Compilation A list of SAMA candidates was developed by reviewing industry documents and considering plant-specific enhancements not identified in published industry documents. Since ANO-2 is a conventional Combustion Engineering nuclear power reactor, considerable attention was paid to the SAMA candidates from SAMA analyses for other CE plants. Attention was also paid to the generation and screening of plant-specific enhancements documented in the ANO-1 SAMA evaluation. Industry documents reviewed include the following:

Calvert Cliffs Nuclear Power Plant SAMA Analysis (Reference E.2-1)

Combustion Engineering System 80+ SAMDA Analysis (Reference E.2-2)

Arkansas Nuclear One Unit 1 SAMA Evaluation (Reference E.2-3)

The above documents represent a compilation of SAMA candidates developed from other industry documents. These sources of industry documents include:

Watts Bar Nuclear Plant Unit 1 PRA/IPE submittal Limerick SAMDA cost estimate report NUREG-1437 description of Limerick SAMDA NUREG-1437 description of Comanche Peak SAMDA Watts Bar SAMDA submittal TVA response to NRCs RAI on the Watts Bar SAMDA submittal Westinghouse AP600 SAMDA Safety Assessment Consulting presentation by Wolfgang Werner at the NUREG-1560 conference NRC IPE Workshop - NUREG-1560 NRC Presentation NUREG-0498, Supplement 1, Section 7 NUREG/CR-5567, PWR Dry Containment Issue Characterization NUREG-1560, Volume 2, NRC Perspectives on the IPE Program Environmental Report Page E-16 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage NUREG/CR-5630, PWR Dry Containment Parametric Studies NUREG/CR-5575, Quantitative Analysis of Potential Improvements for the Dry PWR Containment ICONE paper by C. W. Forsberg, et. al., on a core melt source reduction system In addition to SAMA candidates from review of industry documents, additional SAMA candidates were obtained from plant-specific sources, such as the ANO-2 Individual Plant Examination (IPE) (Reference E.2-4) and Individual Plant Evaluation of External Events (IPEEE) (Reference E.2-5). In both the IPE and IPEEE, several enhancements related to severe accident design performance were recommended. These nineteen enhancements were included in the comprehensive list of SAMA candidates and are listed below.

SAMA Candidates Obtained from the IPE (Reference E.2-4)

CB-22 Provide procedural verification that the shutdown cooling system is secured during startup by local verification that the shutdown cooling suction line isolation valves are closed. This additional check would reduce the potential for an interfacing system LOCA to be introduced through this path due to inadvertent valve mis-positioning resulting from valve failure to stroke properly.

CB-23 Add a procedural requirement to close manual valve 2HPA-2 to ensure that failure of 2SV-8231-2 will not introduce a small containment leak path.

CB-24 The potential exists during a degraded power condition for an unisolated leak path to develop from the containment through the 2" vent header line to the waste gas surge tank (2T17) via valves 2CV-2400-2 and 2CV-2401-1. Should this path be open prior to a degraded power (loss of AC) condition, the degraded power procedure could be used to ensure that these valves are closed, and to manually close 2CV-2401-1 or manual valve 2CVH-8, which is in series with these valves.

This SAMA would increase the probability of successful containment isolation when required.

CB-25 Reorient 2CV-5254-2 to oppose potential flow from the reactor coolant system to reduce the potential of an interfacing system LOCA through a ruptured reactor coolant pump seal cooler tube. Increase component cooling water relief capacity to minimize the likelihood of the component cooling water piping breaking between 2CV-5255-1 and the containment penetration.

CW-23 Enhance loss of service water procedures to improve the ability to avoid unnecessary low pressure safety injection and containment spray pump overheating failures that can minimize the benefit of restoring service water.

EV-31 Remove check valve internals to improve the potential for cooling communication between molten core debris in the bottom of the cavity and water on the Environmental Report Page E-17 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage containment floor. Improved cooling of a failed core would decrease the potential for a post severe accident off-site release.

FW-17 Enhance emergency operating procedures to place emergency feedwater flow control valves in an open position once it has been determined that main steam isolation signal conditions do not exist. If the outboard flow control valves from both the motor-driven and turbine-driven pumps were in a full open position upon loss of power supply, the potential for loss of flow to both steam generators would be minimized.

OT-09 Flood fuel transfer tube in the event of core damage. This would reduce the potential for a high-temperature induced failure of the fuel transfer tube flange seals during accidents involving high pressure melt ejection. This action would help cool the transfer tube flange and its seals and would help scrub fission products escaping through failed seals.

SAMA Candidates Obtained from the IPEEE (Reference E.2-5)

IPEEE-01 Bolt control cabinets 2C02, 2C03, 2C04, 2C09, 2C16, 2C17, 2C21, 2C21-1, 2C22, and 2C23 together.

IPEEE-02 Ensure that the doors to cabinet 2C21-2 latch properly.

IPEEE-03 Connect back-to-back motor control centers 2B-54 & 2B-64 so they respond together during an earthquake.

IPEEE-04 Inspect the rear anchorage of 480V load centers.

IPEEE-05 Provide an additional anchorage for control cabinet 2C80.

IPEEE-06 Ensure the protection of control cabinet 2C80 during a seismic event. Control cabinet 2C80 has an adjacent instrumentation cabinet that could topple during an earthquake. Additionally, a fire extinguisher is nearby on a fairly short hook that could fall and become a potential missile.

IPEEE-07 Move breaker adjustment cranks from 480V load centers 2B-5 & 2B-6.

IPEEE-08 Close open S-hooks on light fixtures above motor control centers 2B-51 & 2B-61.

IPEEE-09 Further investigate the calculated value for high confidence low probability of failure

(<0.3g) for the emergency diesel fuel tanks 2T-57A & 2T-57B.

IPEEE-10 Tighten doors of control cabinet 2C-16 so they do not rattle during an earth quake.

IPEEE-11 Further investigate the calculated value for high confidence low probability of failure

(<0.3g) for inverters 2A-3 and 2A-4.

Environmental Report Page E-18 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage The current ANO-2 PSA model was also used to identify plant-specific modifications for inclusion in the comprehensive list of SAMA candidates. The top 100 cut sets from the PSA model were reviewed for patterns that could be addressed through a potential enhancement to the plant. Sixteen postulated modifications were developed, included in the list of SAMA candidates, and listed below.

SAMA Candidates Obtained from the Current PSA Model AC/DC-24 Create the ability to automatically transfer battery charger/eliminator 2D31B to an alternate power source upon demand. This SAMA would reduce the potential for human error in transferring battery charger 2D31B to an alternate power source.

CB-26 Change plant operating procedures to isolate the low pressure safety injection line following the failure of series system check valves. Also, enhance operator training on coping with interfacing system LOCAs resulting from reactor coolant pump seal cooler tube ruptures.

CC-18 Prevent plugging of the containment sump strainers by modifying the existing strainers and adding additional strainer area.

CC-19 Provide an additional flow path from the refueling water tank to the high-pressure safety injection system through a diversified suction flow path check valve. This SAMA would reduce the potential for common cause failure of refueling water tank flow path check valves.

CC-20 Replacing either containment sump valve 2CV-5649-1 or 2CV-5650-2 with an air-operated valve. This would reduce the potential for common cause failure of these valves preventing adequate core cooling.

CC-21 Reduce the potential for common cause failure of high-pressure safety injection motor-operated valves by replacing redundant train valve actuators with diversified valve actuators.

CC-22 Reduce the potential of common cause failure of two or more recirculation actuation signal and engineered safety features actuation signal actuation relays (e.g.,

K104A/B, SSR-1/3A, etc.) This modification would replace existing relays with relays of a diverse design.

CC-23 Increase the reliability of automatic recirculation swap over. This modification would install an additional level transmitter and change the recirculation actuation logic from 2-out-of-4 to 2-out-of-5.

CC-24 Provide a bypass flow path with a normally open motor-operated control valve around the safety injection tank discharge control valves. This modification would increase the probability of injection if the motor-operated control valves fail closed.

Environmental Report Page E-19 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage CW-09 Provide an additional diversified service water pump. Decrease the frequency of core damage due to a loss of service water by installing an additional service water pump with an independent diesel generator. This modification also requires that one of the remaining service water pumps be supplied with an independent diesel to reduce the potential for common cause failure of all of the service water pumps.

CW-24 Provide the ability to automatically trip the reactor coolant pumps on a loss of component cooling water. This SAMA would reduce the potential for a seal LOCA following a loss of component cooling water by reducing the reliance on operator action to trip the reactor coolant pumps.

CW-25 Add a redundant valve in series with 2CV-1530-1 on service water header 1 (and 2CV-1531-2 on service water header 2). This SAMA would increase the reliability of isolation if the isolation valves supplying the component cooling water heat exchangers and main chillers fail to close upon demand.

CW-26 Reduce the failure frequency of the service water system. This SAMA would increase the inspection and cleaning frequency of the service water pump discharge filters, reducing the probability of a common cause failure.

CW-27 Reduce the failure frequency of the service water system. This SAMA would install backwash filters in place of the existing strainers, reducing the probability of a common cause failure.

EV-30 Reduce the potential for common cause failure of containment spray system motor-operated valves by replacing redundant train motor-operated valve actuators with diverse valve actuators.

FW-19 Create the ability to automatically align emergency feedwater/auxiliary feedwater suction to the other condensate storage tank on low-low level of 2T-41A or 2T-41B.

This modification would reduce the potential for a loss of feedwater.

The comprehensive list contained a total of 192 SAMA candidates.

E.2.2 Qualitative Screening of SAMA Candidates The purpose of the preliminary SAMA screening was to eliminate from further consideration enhancements that were not viable for implementation at ANO-2. Potential SAMA candidates were screened out if they modified features not applicable to ANO-2, if they had already been implemented at ANO-2, or if they were similar in nature and could be combined with another SAMA candidate to develop a more comprehensive or plant-specific SAMA candidate.

During this process, 99 of the 192 original SAMA candidates were eliminated, leaving 93 SAMA candidates for further analysis. These 93 improvements are listed in Table E.2-1.

Environmental Report Page E-20 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage The final screening process involved identifying and eliminating those items whose cost exceeded their benefit as described below. Table E.2-1 provides a description of each of the 93 SAMA candidates.

E.2.3 Final Screening of SAMA Candidates A benefits analysis was performed on each of the remaining SAMA candidates. The benefit was defined as the sum of the dollar equivalents for each severe accident impact (off-site exposure, off-site economic costs, occupational exposure, and on-site economic costs). If the expected cost exceeded the estimated benefit, the SAMA was not considered cost-beneficial.

Implementation of each SAMA candidate would change the severe accident risk (i.e., a change in frequency or consequence of severe accidents). Bounding evaluations (or analysis cases) were performed to address specific SAMA candidates or groups of similar SAMA candidates.

These analysis cases overestimated the benefit and thus were conservative calculations. For example, one SAMA candidate suggested installing a digital large break LOCA protection system. The bounding calculation estimated the benefit of this improvement by total elimination of risk due to large break LOCAs (see analysis case LBLOCA, below). This calculation obviously overestimated the benefit, but if the inflated benefit indicated that the SAMA candidate was not cost-beneficial then the purpose of the analysis was satisfied. A description of the analysis cases used in the evaluation follows.

AIR This analysis case was used to evaluate the change in the plant risk profile that would be achieved if the plant air compressors were replaced with a more reliable model. Although the proposed SAMA would not completely eliminate air compressor failures, a bounding benefit was estimated by setting the plant air compressor failure events to zero. Perfectly reliable air compressors result in minimal benefit. This analysis case was used to model the benefit of SAMA IA-02.

ATWS1 This analysis case was used to estimate the maximum attainable benefit from enhancements related to ATWS coping. For this case, the maximum attainable benefit of ATWS reduction was estimated by multiplying the results of the MAXBENEFIT case by the ratio of the CDF contribution of an ATWS to the total CDF, [(ATWS CDF)/ (Total CDF)*(MAXBENEFIT)]. The ATWS contribution to core damage is 1.59E-6. Elimination of core damage due to an ATWS results in a benefit of approximately $140,000. This analysis case was used to model the benefit of SAMAs AT-01, AT-02 and AT-03.

ATWS2 This analysis case was used to estimate the benefit associated with increasing the charging pump lube oil capacity. The benefit was obtained by multiplying the results of the MAXBENEFIT case by the ratio of the change in the CDF of an ATWS to the total CDF of ANO-2 (i.e., [{ATWS CDF/Total CDF}*{MAXBENEFIT}]). The ATWS contribution to core damage is Environmental Report Page E-21 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage 1.59E-6. The ATWS frequency is derived from three sequence groups: Turbine Trip (1.34E-6/yr), Loss of MFW (1.26E-7/yr), and LOOP (1.25E-7/yr). Examination of the ATWS cut sets (Reference E.2-7) indicates that for top event BW (borated water addition) following turbine trip/loss of MFW, 9.5% of the top event probability is from cut sets that include failure of at least one charging pump. For top event BW following a LOOP, 0.38% of the top event probability is from cut sets that include charging pump failure. To approximate the benefit from this SAMA, these percentages were applied to the ATWS sequence frequencies above. Hence, the revised ATWS CDF (1.45E-6) is an estimate of the fraction of the initial ATWS CDF not associated with charging pump failure. Therefore, the benefit associated with making the charging pumps perfectly reliable has an estimated value of $12,000. This analysis case was used to model the benefit of SAMA CW-07.

BRKR This analysis case was used to evaluate the change in the plant risk profile that would be achieved if procedures were enhanced to repair or change out failed 4160VAC breakers.

Although the proposed SAMA would not eliminate all potential failures of the 4160VAC breakers, a bounding benefit was estimated by removing the 4160VAC breaker gates.

Elimination of all 4160V breaker failures results in a benefit of approximately $6,000. This analysis case was used to model the benefit of SAMA AC/DC-15.

CAVITY This analysis case was used to evaluate the change in the plant risk profile that would be achieved if reactor cavity flooding ability was enhanced. Plant damage state IVKi is dominated by a sequence initiated by a transient event, followed by unsuccessful secondary cooling, successful once-through cooling during the injection mode and failure of HPSI during the recirculation mode as a result of high temperature containment sump water combined with high room temperature. Removal of the internals from check valve 2BS-46 was recommended in the ANO-2 IPE to mitigate this type of sequence. Although the proposed SAMAs would not completely eliminate the potential for such a scenario, a bounding benefit was estimated by removing all risk contribution attributable to this PDS. Elimination of core damage attributable to plant damage state IVKi results in a benefit of approximately $17,000. This analysis case was used to model the benefit of SAMAs EV-15, EV-16, EV-17, and EV-31.

CBPEN This analysis case was used to evaluate the change in the plant risk profile that would be achieved if the station blackout procedure included a requirement to close manual valve 2HPA-

2. PDS SBOu is composed of station blackout events with unsuccessful containment isolation.

In this scenario, combinations of DC and AC power failures could result in failure of 2SV-8231-2 to close or remain closed. Removal of this PDS is the modeling equivalent of manually closing 2HPA-2, which was recommended in the ANO-2 IPE to ensure that failure of 2SV-8231-2 will not introduce a containment leak path. Although the proposed SAMA would not completely eliminate the potential for such a scenario, a bounding benefit was estimated by eliminating this PDS. Elimination of all core damage attributable to plant damage state SBOu results in a Environmental Report Page E-22 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage benefit of approximately $200. This analysis case was used to model the benefit of SAMA CB-23.

CST This analysis case was used to evaluate the change in the plant risk profile that would be achieved if the ability to automatically align EFW/AFW suction to the alternate condensate storage tank was installed. Although the proposed SAMA would not completely eliminate the potential failures, a bounding benefit was estimated by removing the human failure event for suction alignment. Perfectly reliable re-alignment of EFW/AFW suction to the alternate condensate storage tank results in a benefit of approximately $10,000. This analysis case was used to model the benefit of SAMA FW-19.

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. Station battery capacity of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> results in a benefit of approximately $34,000. This analysis case was used to model the benefit of SAMAs AC/DC-04, AC/DC-05, AC/DC-10, AC/DC-12, and AC/DC-24.

EDGCOOL This analysis case was used to evaluate the change in the plant risk profile that would be achieved if a back-up source of EDG cooling was installed. Although the proposed SAMA would not completely eliminate the potential for such a failure, a bounding benefit was estimated by removing EDG service water cooling gates. Perfectly reliable EDG cooling results in a benefit of approximately $20,000. This analysis case was used to model the benefit of SAMA AC/DC-19.

EFW This analysis case was used to evaluate the change in the plant risk profile that would be achieved following modifications making EFW more reliable, such as installing an independent diesel for the condensate storage tank makeup pumps or switching EFW room cooling power to station batteries in a station blackout. Although none of the proposed changes would completely eliminate EFW failures, a bounding benefit was estimated by removing all EFW system failure gates. A perfectly reliable EFW system results in a benefit of approximately

$104,000. This analysis case was used to model the benefit of SAMAs FW-13 and HV-05.

EFWCV This analysis case was used to evaluate the change in the plant risk profile that would be achieved by modifying procedures directing operators to open the emergency feedwater flow control valves to the steam generators following failure due to power supply or signal failure.

Environmental Report Page E-23 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage Although the proposed SAMA would not completely eliminate the potential for such a failure, a bounding benefit was estimated by setting the corresponding human failure event to zero.

Elimination of operator failure to open the emergency feedwater flow control valves results in a benefit of approximately $17,000. This analysis case was used to model the benefit of SAMA FW-17.

ESFASRELAY This analysis case was used to evaluate the change in the plant risk profile that would be achieved if the engineered safety features actuation system actuation and solid state relays were replaced with diverse designs. Although the proposed SAMA would not completely eliminate the potential for such a failure, a bounding benefit was estimated by eliminating the ESFAS actuation relay common cause failure events. Elimination of all core damage due to common cause failure of engineered safety features actuation and solid state relays results in a benefit of approximately $15,000. This analysis case was used to model the benefit of SAMA CC-22.

FDW This analysis case was used to evaluate the change in the plant risk profile that would be achieved if a digital feedwater upgrade was installed or modifications were made to cap the downstream piping of normally closed CCW drain and vent valves. Although none of the proposed changes would completely eliminate MFW failures, a bounding benefit was estimated by removing the loss of feedwater initiating event and MFW failure gates. Elimination of all core damage due to loss of feedwater results in a benefit of approximately $112,000. This analysis case was used to model the benefit of SAMA CW-01 and FW-01.

FILTER This analysis case was used to evaluate the change in the plant risk profile that would be achieved by increasing the inspection frequency of the service water pump discharge filters or replacing them with backwash filters. Although none of the proposed changes would completely eliminate service water pump discharge filter failures, a bounding benefit was estimated by removing the service water pump discharge filter common cause failure event. Elimination of all common cause failures of service water pump discharge filters results in a benefit of approximately $100,000. This analysis case was used to model the benefit of SAMAs CW-26 and CW-27.

HPSICV This analysis case was used to evaluate the change in the plant risk profile that would be achieved by providing an additional flow path from the refueling water tank to the high pressure safety injection system. Although the proposed SAMA would not completely eliminate the potential failure, a bounding benefit was estimated by removing the HPSI system check valve failure events. Elimination of all core damage due to failure of the high-pressure safety injection flow path check valves results in a benefit of approximately $29,000. This analysis case was used to model the benefit of SAMA CC-19.

Environmental Report Page E-24 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage HPSIMOV This analysis case was used to evaluate the change in the plant risk profile that would be achieved by providing actuator diversity for the MOVs in the HPSI system. Although the proposed SAMA would not completely eliminate this potential failure, a bounding benefit was estimated by removing the HPSI MOV common cause failure event. Elimination of all core damage due to common cause failure of the high-pressure safety injection valves results in a benefit of approximately $22,000. This analysis case was used to model the benefit of SAMA CC-21.

HVAC This analysis case was used to evaluate the change in the plant risk profile that would be achieved if procedures were developed for temporary HVAC. Although the proposed SAMA would not completely eliminate the potential for such a failure, a bounding benefit was estimated by removing the shutdown heat exchanger room cooling failure gates. Perfectly reliable shutdown heat exchanger room cooling results in a benefit of approximately $174,000. This analysis case was used to model the benefit of SAMAs HV-03.

ISLOCA This analysis case was used to evaluate the change in the plant risk profile that would be achieved by reducing the probability or consequences of an ISLOCA event. Although none of the proposed changes would completely eliminate the occurrence or impact of ISLOCA events, a bounding benefit was estimated by removing the ISLOCA event. Elimination of all core damage from ISLOCA results in a benefit of approximately $86,000. This analysis case was used to model the benefit of SAMAs CB-13, CB-14, CB-19, and CB-20.

ISLOCAHEP This analysis case was used to evaluate the change in the plant risk profile that would be achieved if procedures, associated with operation and maintenance of systems interfacing the reactor coolant system, were enhanced. Although the proposed SAMA would not completely eliminate the potential for human failures, a bounding benefit was estimated by assuming perfect human reliability in the operation and maintenance of the systems interfacing the RCS.

Elimination of all human error associated with an interfacing system LOCA results in a benefit of approximately $64,000. This analysis case was used to model the benefit of SAMA CB-26.

LBLOCA This analysis case was used to evaluate the change in the plant risk profile that would be achieved if a digital large break LOCA (LBLOCA) protection system was installed. Although the proposed change would not completely eliminate the potential for a LBLOCA, a bounding benefit was estimated by removing the LBLOCA initiating event. Elimination of all core damage due to large LOCAs results in a benefit of approximately $24,000. This analysis case was used to model the benefit of SAMA OT-07.

Environmental Report Page E-25 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage LOCCW This analysis case was used to evaluate the change in the plant risk profile that would be achieved if the ability to cool the shutdown cooling heat exchangers was improved or an additional CCW pump was installed. Although the proposed SAMAs would not completely eliminate the potential for a loss of component cooling water, a bounding benefit was estimated by removing the component cooling water header failure gates. Elimination of all core damage due to loss of the component cooling water system results in a benefit of approximately

$76,000. This analysis case was used to model the benefit of SAMAs CW-15 and CW-22.

LOOP This analysis case was used to evaluate the change in the plant risk profile that would be achieved if the reliability of the Class 1E power distribution system was improved. Although none of the proposed changes would reduce the LOOP frequency to zero, a bounding benefit was estimated by removing the LOOP initiating event. Elimination of all loss of off-site power initiators results in a benefit of approximately $39,000. This analysis case was used to model the benefit of SAMAs AC/DC-02, AC/DC-09, AC/DC-13, AC/DC-20, AC/DC-21, and AC/DC-22.

LOOPREC This analysis case was used to evaluate the change in the plant risk profile which would be achieved if the plant recovery steps following a station blackout were emphasized through enhanced training and procedural guidance. Although the proposed SAMA would not ensure instantaneous recovery of on-site equipment during a LOOP, a bounding benefit was estimated by removing events for LOOP non-recovery factors with one or more run failures.

It is difficult to separate the human element from the equipment failure element in the loss of off-site power recovery model. These particular recoveries are used for those cut sets that involved convolution of the mission time failure model with the LOOP recovery time model. In essence, removing these events is equivalent to assuming that none of the LOOP cut sets with time-dependent failures occur. This approximates a perfect operator that ensures no additional failures occur, after the initial transient, before off-site power is recovered. This is a very conservative treatment because it is obviously beyond the power of the operators to completely reduce the equipment run-time failure probability to zero or recover off-site power instantly.

Instantaneous recovery of on-site equipment during a loss of off-site power event results in a benefit of approximately $34,000. This analysis case was used to model the benefit of SAMA AC/DC-16.

LOSW This analysis case was used to evaluate the change in the plant risk profile that would be achieved if an additional diversified service water pump was installed, or if the ECCS pump motors were replaced with air cooled motors. Although the proposed SAMAs would not completely eliminate the potential for core damage due to a loss of the service water, a bounding benefit was estimated by removing service water pump train failure events.

Environmental Report Page E-26 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage Elimination of all core damage due to loss of service water results in a benefit of approximately

$202,000. This analysis case was used to model the benefit of SAMAs CW-09 and CW-13.

LOSWHEP This analysis case was used to evaluate the change in the plant risk profile that would be achieved if procedures following loss of service water were enhanced. Also, since the results of this analysis case were deemed conservatively representative of other plant support systems, it was used to evaluate the change in the plant risk profile that would be achieved if procedures for other plant support systems were enhanced. Although the proposed SAMAs would not completely eliminate the potential for such a failure, a bounding benefit was estimated by removing all service water human failure events. Perfectly reliable recovery of service water results in a benefit of approximately $25,000. This analysis case was used to model the benefit of SAMAs CW-06, CW-21, and CW-23.

MAXBENEFIT This analysis case was used to determine the maximum benefit attainable by removing all severe accident risk associated with the operation of ANO-2 (i.e., eliminating all contributors to core damage). This analysis case was used to evaluate SAMA candidates suggesting installation of new systems or trains, such as an additional HPSI pump with independent diesel or passive secondary side coolers. Elimination of all core damage results in a benefit of approximately $632,000. This analysis case was used to model the benefit of SAMAs CC-01, CC-02, CC-07, CC-14, FW-15, FW-18, OT-02 and OT-06.

OFFSITE This analysis case was used to assess the total elimination of all off-site release from the plant following an accident resulting in degradation of the reactor core. A number of the SAMAs are associated with reducing the magnitude or consequences of an off-site release. Although the proposed modifications would not be expected to reduce the actual off-site consequences to zero this bounding case estimated the maximum benefit attainable by totally eliminating off-site release. This case is equal to the total off-site benefit of the MAXBENEFIT case. Elimination of all off-site releases results in a benefit of approximately $178,000. This analysis case was used to model the benefit of SAMAs CB-07, EV-02, EV-04, EV-05, EV-07, EV-08, EV-09, EV-10, EV-11, EV-12, EV-19, EV-20, EV-21, EV-22, EV-23, EV-25, EV-26, EV-27, EV-28 and EV-29.

RASLEVEL This analysis case was used to evaluate the change in the plant risk profile that would be achieved if an additional RAS level transmitter was installed and the logic changed from 2-out-of-4 to 2-out-of-5. Although the proposed SAMA would not completely eliminate the potential for such a failure, a bounding benefit was estimated by removing the RAS level transmitter failure events. Elimination of all core damage due to failure of the recirculation actuation signal level transmitters results in a benefit of approximately $5,000. This analysis case was used to model the benefit of SAMA CC-23.

Environmental Report Page E-27 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage SEALLOCA This analysis case was used to evaluate the change in the plant risk profile that would be achieved if the reactor coolant pumps automatically tripped on a loss of CCW, if the reactor coolant pump seals were improved, or if an independent reactor coolant pump seal injection system was installed. Although the proposed SAMAs would not completely eliminate the potential for a seal LOCA, a bounding benefit was estimated by removing the reactor coolant pump seal LOCA gate. Elimination of all seal LOCAs results in a benefit of approximately

$71,000. This analysis case was used to model the benefit of SAMAs CW-10, CW-11, CW-14, and CW-24.

SGTR This analysis case was used to evaluate modifications that would reduce the frequency of tube ruptures or would improve the ability to mitigate a SGTR. Although none of the proposed changes would reduce the core damage contribution from SGTRs to zero, a bounding benefit was estimated by removing the SGTR initiating event. Elimination of all steam generator tube ruptures results in a benefit of approximately $25,000. This analysis case was used to model the benefit of SAMAs CB-01, CB-03, CB-04, CB-08, and CB-10.

SIGNAL This analysis case was used to evaluate the change in the plant risk profile that would be achieved if operator response to inadvertent actuation signals of engineered safety functions was enhanced by additional training. Although the proposed SAMA would not completely eliminate the impact of inadvertent actuation, a bounding benefit was removing all of the gates for spurious actuation of engineered safety functions. Assuming perfect reliability of 120VAC buses results in a benefit of approximately $5,000. This analysis case was used to model the benefit of SAMA AC/DC-06.

SIMOV This analysis case was used to evaluate the change in the plant risk profile that would be achieved if bypass flow paths were provided for all safety injection tank discharge lines.

Although the proposed SAMA would not completely eliminate the effects of this potential failure, a bounding benefit was estimated by removing all failures of the safety injection tank discharge MOVs. Elimination of all core damage due to failure of safety injection tank discharge valves results in a benefit of approximately $4,000. This analysis case was used to model the benefit of SAMA CC-24.

SPRAYMOV This analysis case was used to evaluate the change in the plant risk profile that would be achieved if the containment spray MOV actuators were diversified. Although the proposed SAMA would not completely eliminate the potential for such a failure, a bounding benefit was estimated by removing the containment spray MOV common cause failure events. Elimination Environmental Report Page E-28 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage of all core damage due to common cause failure of containment spray valves results in a benefit of approximately $38,000. This analysis case was used to model the benefit of SAMA EV-30.

SUMPMOV This analysis case was used to evaluate the change in the plant risk profile that would be achieved if the containment sump motor-operated valves were diversified. Although the proposed SAMA would not completely eliminate the potential failure of containment sump MOVs, a bounding benefit was estimated by removing all containment sump MOV failure events. Elimination of all core damage due to containment sump valve failures results in a benefit of approximately $31,000. This analysis case was used to model the benefit of SAMA CC-20.

SUMPSTRAIN This analysis case was used to evaluate the change in the plant risk profile that would be achieved if the containment sump strainers were modified to prevent plugging. Although the proposed SAMA would not completely eliminate sump strainer plugging, a bounding benefit was estimated by removing the containment sump strainer failure event. Elimination of sump strainer plugging contribution to core damage results in a benefit of approximately $36,000.

This analysis case was used to model the benefit of SAMA CC-18.

SWMOV This analysis case was used to evaluate the change in the plant risk profile that would be achieved if redundant control valves were placed in series with the service water to CCW isolation valves. Although the proposed SAMA would not completely eliminate the potential for such a failure, a bounding benefit was estimated by removing the service water to CCW isolation valve failure to close event. Elimination of all core damage due to service water to CCW isolation valve failure results in a benefit of approximately $10,000. This analysis case was used to model the benefit of SAMA CW-25.

TDPUMPDC This analysis case was used to evaluate the change in the plant risk profile that would be achieved if portable generators were used to power the turbine driven emergency feedwater pump controls after station batteries are depleted. Although the proposed SAMA would not completely eliminate the potential for such a failure, a bounding benefit was estimated by removing the DC power gates to the turbine driven emergency feedwater pump logic.

Elimination of turbine-driven pump dependence on DC power results in a benefit of approximately $5,000. This analysis case was used to model the benefit of SAMA FW-08.

Values for avoided public and occupational health risk were converted to a monetary equivalent (dollars) via application of the NUREG/BR-0184 (Reference E.2-7) conversion factor of $2,000 per person-rem and discounted to present value. Values for avoided off-site economic costs were also discounted to present value. If the net value of a SAMA was negative, the cost of the enhancement was greater than the benefit and the SAMA was not cost beneficial.

Environmental Report Page E-29 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage The expected cost of implementation of each SAMA was established from existing estimates of similar modifications combined with engineering judgment. Most of the cost estimates were developed from similar modifications considered in previous performed SAMA and SAMDA analyses. In particular, these cost-estimates were derived from the three major sources including:

Calvert Cliffs SAMA Analysis (Reference E.2-1)

Westinghouse-CE System 80+ SAMDA Analysis (Reference E.2-2)

ANO-1 SAMA Analysis (Reference E.2-3)

The cost estimates did not include the cost of replacement power during extended outages required to implement the modifications, nor did they include contingency costs associated with unforeseen implementation obstacles. Estimates based on modifications that were implemented or estimated in the past were presented in terms of dollar values at the time of implementation (or estimation), and were not adjusted to present-day dollars. In addition, several implementation costs were originally developed for SAMDA analyses (i.e., during the design phase of the plant), and therefore, do not capture the additional costs associated with performing design modifications to existing plants (i.e., reduced efficiency, minimizing dose, disposal of contaminated material, etc.). Therefore, the cost estimates were conservative.

As this analysis focuses on establishing the economic viability of potential plant enhancement when compared to attainable benefit, often detailed cost estimates were not required to make informed decisions regarding the economic viability of a particular modification. Several of the SAMA candidates were clearly in excess of the attainable benefit estimated from a particular analysis case. For less clear cases, engineering judgment was applied to determine if a more detailed cost estimate was necessary to formulate a conclusion regarding the economic viability of a particular SAMA. In most cases, more detailed cost estimates were not required, particularly if the SAMA called for the implementation of a hardware modification. Nonetheless, the cost of all SAMA candidates was conceptually estimated to the point where conclusions regarding the economic viability of the proposed modification could be adequately gauged.

The cost-benefit comparison and disposition of each of the 93 SAMA candidates is presented in Table E.2-1.

E.2.4 Sensitivity Analyses Several sensitivity analyses were conducted to gauge the impact of assumptions upon the analysis. The benefits estimated for each of these sensitivities are presented in Table E.2-2.

A description of each sensitivity case follows:

Sensitivity Case #1: Repair/Refurbishment The purpose of this sensitivity case was to investigate the impact of assuming damaged plant equipment is repaired and refurbished following an accident scenario, as opposed to Environmental Report Page E-30 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage automatically decommissioning the facility following the event. For the purpose of this analysis, the cost of repair and refurbishment over the lifetime of the plant was assumed to be equivalent to 20% of the replacement power cost in accordance with NUREG/BR-0184 (Reference E.2-7).

The sensitivity case #1 results for all of the SAMA candidates were lower than the base case results and therefore, lower than the estimated costs.

Sensitivity Case #2: Conservative Discount Rate The purpose of this sensitivity case was to investigate the sensitivity of each analysis case to the discount rate. The discount rate of 7.0% used in the base case analyses is conservative relative to corporate practices. Nonetheless, a lower discount rate of 5.0% was assumed in this case. The sensitivity case #2 results for a few of the SAMA candidates were slightly higher than the estimated cost. However, due to conservatism in the benefit estimates and the sensitivity case results, and the fact that most of the costs were estimated only to the point of obtaining reasonable assurance that they were higher than the baseline benefit estimate, these SAMA candidates are still not cost effective for ANO-2.

Sensitivity Case #3: Best-Estimate Discount Rate The purpose of this sensitivity case was to investigate the sensitivity of each analysis case to the discount rate. The discount rate of 7.0% used in the base case analyses is considered conservative. This analysis case uses a higher discount rate of 15%, as suggested by Entergy, as a best estimate rate to investigate the impact on each analysis case. The sensitivity case #3 results for all of the SAMA candidates were lower than the base case results and therefore, lower than the estimated costs.

Sensitivity Case #4: High Estimated Dose (On-Site)

The purpose of this sensitivity case was to investigate the sensitivity of each analysis case to the on-site dose estimates. For the base case analyses, the immediate and long-term on-site dose to plant personnel following a severe accident was assumed to be 3,300 and 20,000 rem respectively. This analysis case assumed high estimated dose values of 14,000 and 30,000 rem for immediate and long-term on-site dose, respectively, as suggested in NUREG/BR-0184 (Reference E.2-7). The sensitivity case #4 results for a few of the SAMA candidates were slightly higher than the estimated cost. However, due to conservatism in the benefit estimates and the sensitivity case results, and the fact that most of the costs were estimated only to the point of obtaining reasonable assurance that they were higher than the base case benefit estimate, these SAMA candidates are still not cost effective for ANO-2.

Sensitivity Case #5: High On-Site Cleanup Cost The purpose of this sensitivity case was to investigate the sensitivity of each analysis case to the total on-site cleanup cost. For the base case analyses, the total on-site cleanup cost following a severe accident was assumed to be $1,500,000. This analysis case assumed a high estimated on-site cleanup cost of $2,000,000 as suggested in NUREG/BR-0184 (Reference E.2-7). The sensitivity case #5 results for a few of the SAMA candidates were slightly higher than the estimated cost. However, due to conservatism in the benefit estimates and the Environmental Report Page E-31 Arkansas Nuclear One - Unit 2

Arkansas Nuclear One - Unit 2 Applicants Environmental Report Operating License Renewal Stage sensitivity case results, and the fact that most of the costs were estimated only to the point of obtaining reasonable assurance that they were higher than the base case benefit estimate, these SAMA candidates are still not cost effective for ANO-2.

E.2.5 References E.2-1 Generic Environmental Impact Statement for License Renewal of Nuclear Plants, (regarding Calvert Cliffs Nuclear Power Plant, Units 1 and 2), U.S. Nuclear Regulatory Commission, NUREG-1437, Supplement 1.

E.2-2 Final Safety Evaluation Report Related to the Certification of the System 80+ Design, NUREG 1462, NRC, August 1994.

E.2-3 Arkansas Nuclear One Unit 1 SAMA Analysis, E.A. Krantz, Analysis File Number ANO1 AF-3, Report Number 99-R-1007-01, January 2000.

E.2-4 ANO-2 Probabilistic Risk Assessment (PRA) Individual Plant Examination (IPE)

Submittal, Report Number 94-R-2005-01, March 1994.

E.2-5 Individual Plant Examination of External Events/Fires, T.D. Robinson, Report Number 85-E-0053-48, Rev. 2, March 1996 See also:

ANO-2 IPEEE Fire P2 Values, R. Harris, Report Number 95-E-0066-01, Rev. 2, January 1999.

IPEEE High Confidence of Low Probability of Failure (HCLPF) Calculations for ANO-2 Mechanical and Electrical Equipment and Block Walls, Report Number 96-SQ-2001-01, Rev. 1, May 1996.

IPEEE Other Events, Report Number 94-R-0016-01, Rev.1, December 1994.

IPEEE Seismic Margins Assessment (SMA) of Arkansas Nuclear One, Unit 2, Report Number 96-R-2016-02, Rev. 0, May 1996.

USI A-46/IPEEE Horizontal Tank and Heat Exchanger Report and Review, Report Number 95-SQ-2021-02, Rev. 0, September 1996 E.2-6 SW Pump Strainer Backwash Device, ER010551R201 Rev. 0, November, 2001.

E.2-7 Regulatory Analysis Technical Evaluation Handbook, NUREG/BR-0184, January 1997.

E.2-8 ANO-2 ATWS Scoping Report, 89-E-0048-26, Rev 2, December 1997.

Environmental Report Page E-32 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO AC/DC POWER RELIABILITY OR AVAILIABILITY AC/DC- Install a Improve on-site AC 6.08% 5.92% $39,000 $3,350,000 Not Cost Elimination of all loss of off-site power 02 combustion power reliability (i.e., Effective initiators results in a benefit of $39,000 turbine decrease the frequency (analysis case LOOP). In 1998, BG&E generator of a station blackout). estimated the cost of implementing a similar SAMA at Calvert Cliffs to be

$3,350,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

AC/DC- Use fuel cells Extend DC power 5.70% 4.25% $34,000 $2,000,000 Not Cost Station battery capacity of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 04 in lieu of availability during a Effective results in a benefit of $34,000 (analysis conventional station blackout event case DCPWR). In 1998, BG&E lead-acid by replacing station estimated the cost of implementing a batteries batteries with fuel cells similar SAMA at Calvert Cliffs to be that would extend DC $2,000,000. Since the cost of power availability to 24 implementing this SAMA exceeds the hours. attainable benefit, this SAMA is not cost effective for ANO-2.

AC/DC- Provide Ensure longer battery 5.70% 4.25% $34,000 >$150,000 Not Cost Station battery capacity of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 05 additional DC life during a station Effective results in a benefit of $34,000 (analysis battery blackout and case DCPWR). In 1998, BG&E capability consequently reduce estimated the cost of implementing a exposure to long term similar SAMA at Calvert Cliffs to be station blackout $150,000 per battery bank. Since the sequences. cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

AC/DC- Train Improve the chance of 0.90% 0.43% $5,000 $35,000 Not Cost Assuming perfect reliability of 120VAC 06 operations successful response to Effective buses results in a benefit of $5,000 crew for loss of two 120VAC (analysis case SIGNAL). At ANO-2, the response to buses. cost of modifying a plant procedure and inadvertent the associated training is $35,000. Since actuation the cost of implementing this SAMA signals exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

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Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO AC/DC POWER RELIABILITY OR AVAILIABILITY AC/DC- Improve bus cross- Improve AC power 6.08% 5.92% $39,000 $1,119,000 Not Cost Elimination of all loss of off-site power 09 tie capability reliability by installing Effective initiators results in a benefit of $39,000 automatic bus cross- (analysis case LOOP). In 1998, BG&E tie capabilities. estimated the cost of implementing a similar SAMA at Calvert Cliffs to be

$1,119,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

AC/DC- Incorporate alternate Improve DC power 5.70% 4.25% $34,000 $134,000 Not Cost Station battery capacity of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 10 battery charging reliability by either Effective results in a benefit of $34,000 (analysis capabilities cross-tying the AC case DCPWR). In 1998, BG&E buses, or installing a estimated the cost of implementing a portable diesel-driven similar SAMA at Calvert Cliffs to be battery charger. $134,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

AC/DC- Replace current Improve DC power 5.70% 4.25% $34,000 >$150,000 Not Cost Station battery capacity of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 12 station batteries with reliability by installing Effective results in a benefit of $34,000 (analysis a more reliable more reliable station case DCPWR). In 1998, BG&E model batteries. estimated the cost of implementing a similar SAMA at Calvert Cliffs to be

$150,000 per battery bank. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

AC/DC- Create AC power Improve AC power 6.08% 5.92% $39,000 >>$39,000 Not Cost Elimination of all loss of off-site power 13 cross tie capability reliability by installing Effective initiators results in a benefit of $39,000 across units at a AC power cross-tie (analysis case LOOP). The cost of multi-unit site capabilities between implementing this SAMA is judged to ANO-1 and ANO-2. exceed the attainable benefit, even without a detailed cost estimate.

Therefore, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-34 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO AC/DC POWER RELIABILITY OR AVAILIABILITY AC/DC- Develop enhanced Increase probability 1.11% 0.59% $6,000 $35,000 Not Cost Elimination of all 4160V breaker failures 15 procedures to repair of recovery from a Effective results in a benefit of $6,000 (analysis or change out failed failure of breakers case BRKR). At ANO-2, the cost of 4KV breakers that transfer 4.16 kV modifying a plant procedure and the non-emergency associated training is $35,000. Since the buses from unit cost of implementing this SAMA exceeds station service the attainable benefit, this SAMA is not transformers to cost effective for ANO-2.

system station service transformers.

These failures, in conjunction with failure of the diesel generators, lead to loss of emergency AC power.

AC/DC- Emphasize steps in Reduce human error 5.30% 5.32% $34,000 $35,000 Not Cost Instantaneous recovery of on-site 16 plant recovery associated with Effective equipment during a loss of off-site power following a station recovery of station event results in a benefit of $34,000 blackout event blackout events (analysis case LOOPREC). As through enhanced discussed in Section E.2, the LOOPREC training and benefit estimate is very conservative.

procedural guidance. Also, emphasizing recovery of off-site power in operator training may be detrimental to other necessary recovery actions, negating some of the benefit.

Thus, the attainable benefit for this SAMA is much less than $34,000. At ANO-2, the cost of modifying a plant procedure and the associated training is $35,000.

Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-35 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO AC/DC POWER RELIABILITY OR AVAILIABILITY AC/DC- Create a back-up Provide a redundant 3.15% 3.14% $20,000 $1,700,000 Not Cost Perfectly reliable EDG cooling results in a 19 source for diesel source of diesel Effective benefit of $20,000 (analysis case cooling cooling by making the EDGCOOL). In 1998, BG&E estimated emergency diesel the cost of implementing a similar SAMA generators air- at Calvert Cliffs to be $1,700,000. Since cooled. the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

AC/DC- Use fire protection Provide redundancy 6.08% 5.92% $39,000 >$497, 000 Not Cost Elimination of all loss of off-site power 20 systems as a for the diesel cooling Effective initiators results in a benefit of $39,000 backup for diesel support systems. (analysis case LOOP). In 1998, BG&E cooling estimated the cost of implementing a similar SAMA at Calvert Cliffs to be

$497,000 per diesel generator. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

AC/DC- Provide a Increase off-site 6.08% 5.92% $39,000 >$25,000,000 Not Cost Elimination of all loss of off-site power 21 connection to an power redundancy. Effective initiators results in a benefit of $39,000 alternate off-site (analysis case LOOP). In 1998, BG&E power source estimated the cost of implementing a similar SAMA at Calvert Cliffs to be

$25,000,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

AC/DC- Implement Improve off-site 6.08% 5.92% $39,000 >$25,000,000 Not Cost Elimination of all loss of off-site power 22 underground off-site power reliability, Effective initiators results in a benefit of $39,000 power lines particularly during (analysis case LOOP). In 1998, BG&E severe weather. estimated the cost of implementing a similar SAMA at Calvert Cliffs to be

$25,000,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-36 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO AC/DC POWER RELIABILITY OR AVAILIABILITY AC/DC- Create the ability to Reduce the potential 5.70% 4.25% $34,000 >>$34,000 Not Cost Station battery capacity of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 24 automatically for human error in Effective results in a benefit of $34,000 (analysis transfer battery transferring battery case DCPWR). The cost of implementing charger/eliminator charger 2D31B to an this SAMA is judged to exceed the 2D31B to an alternate power attainable benefit, even without a detailed alternate power source. cost estimate. Therefore, this SAMA is source upon not cost effective for ANO-2.

demand ENHANCEMENTS RELATED TO ATWS COPING AT-01 Provide alternative Install a system of 22.2% Not $140,000 $1,000,000 Not Cost Elimination of core damage due to an ATWS pressure relief valves to Estimated Effective ATWS results in a benefit of $140,000 relief valves prevent equipment (analysis case ATWS1). The proposed damage from a modification would result in only a fraction primary coolant of this benefit. In 1993, the cost of pressure spike during implementing a similar SAMA in the an ATWS sequence. Westinghouse-CE System 80+ was This enhancement estimated to be $1,000,000. Since the would improve cost of implementing this SAMA exceeds equipment availability the attainable benefit, this SAMA is not following an ATWS. cost effective for ANO-2.

AT-02 Create a boron Create a boron 22.2% Not $140,000 $300,000 Not Cost Elimination of core damage due to an injection/shutdown injection system by Estimated Effective ATWS results in a benefit of $140,000 system to backup modifying the reactor (analysis case ATWS1). The proposed the mechanical coolant pump seal modification would result in only a fraction control rods cooling system to of this benefit. In 1993, the cost of inject boron using implementing a similar SAMA in the existing sources of Westinghouse-CE System 80+ was boron and existing estimated to be $300,000. Since the cost piping and valves. of implementing this SAMA exceeds the This enhancement attainable benefit, this SAMA is not cost would provide a effective for ANO-2.

redundant means to shut down the reactor.

Environmental Report Page E-37 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO ATWS COPING AT-03 Provide a Provide an additional 22.2% Not $140,000 $3,000,000 Not Cost Elimination of core damage due to an diverse plant diversified plant protection Estimated Effective ATWS results in a benefit of $140,000 protection system to reduce the (analysis case ATWS1). The proposed system frequency of ATWS events modification would result in only a fraction (e.g., ATWS mitigation scram of this benefit. In 1993, the cost of actuation circuitry). implementing a similar SAMA in the Westinghouse-CE System 80+ was estimated to be $3,000,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

ENHANCEMENTS RELATED TO IDENTIFYING OR COPING WITH CONTAINMENT BYPASS CB-01 Institute a Perform eddy-current testing 2.02% 7.52% $25,000 $1,500,000 Not Cost Elimination of all steam generator tube maintenance on 100% of the steam Effective ruptures results in a benefit of $25,000 practice to generator tubes during each (analysis case SGTR). In 1993, the cost perform a 100% refueling outage to reduce of implementing a similar SAMA in the inspection of the frequency of steam Westinghouse-CE System 80+ was steam generator generator tube rupture estimated to be $1,500,000. Since the tubes during events. cost of implementing this SAMA exceeds each refueling the attainable benefit, this SAMA is not outage cost effective for ANO-2.

CB-03 Increase the Increase the secondary side 2.02% 7.52% $25,000 >>$25,000 Not Cost Elimination of all steam generator tube pressure pressure capacity enough Effective ruptures results in a benefit of $25,000 capacity of the that a steam generator tube (analysis case SGTR). The cost of secondary side rupture would not cause the implementing this SAMA is judged to relief valves to lift. This exceed the attainable benefit, even would prevent a direct without a detailed cost estimate.

release pathway to the Therefore, this SAMA is not cost effective environment following a for ANO-2.

steam generator tube rupture.

Environmental Report Page E-38 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO IDENTIFYING OR COPING WITH CONTAINMENT BYPASS CB-04 Install a Enhance depressurization 2.02% 7.52% $25,000 $5,000,000 Not Cost Elimination of all steam generator tube redundant spray capabilities during steam Effective ruptures results in a benefit of $25,000 system to generator tube rupture. (analysis case SGTR). In 1993, the cost depressurize the of implementing a similar SAMA in the primary system Westinghouse-CE System 80+ was during a steam estimated to be $5,000,000. Since the generator tube cost of implementing this SAMA exceeds rupture the attainable benefit, this SAMA is not cost effective for ANO-2.

CB-07 Provide main Route the discharge from the 0% 100% $178,000 $9,500,000 Not Cost Elimination of all off-site releases results steam safety main steam safety valves and Effective in a benefit of $178,000 (analysis case valve and automatic depressurization OFFSITE). In 1993, the cost of automatic valves through a structure in implementing a similar SAMA in the depressurization which a water spray Westinghouse-CE System 80+ was valve scrubbing condenses the steam and estimated to be $9,500,000. Since the removes most of the fission cost of implementing this SAMA exceeds products. This enhancement the attainable benefit, this SAMA is not would reduce the cost effective for ANO-2.

consequences of a steam generator tube rupture.

CB-10 Direct steam Improve scrubbing of steam 2.02% 7.52% $25,000 $35,000 Not Cost Elimination of all steam generator tube generator generator tube rupture Effective ruptures results in a benefit of $25,000 flooding after a releases by maintaining (analysis case SGTR). At ANO-2, the steam generator adequate water coverage of cost of modifying a plant procedure and tube rupture, a ruptured steam generator the associated training is $35,000. Since prior to core tube. the cost of implementing this SAMA damage exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-39 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO IDENTIFYING OR COPING WITH CONTAINMENT BYPASS CB-13 Install additional Install pressure or leak 4.56% 35.87% $86,000 $2,300,000 Not Cost Elimination of all core damage from instrumentation monitoring instruments Effective ISLOCA results in a benefit of $86,000 for interfacing between the first two (analysis case ISLOCA). In 1998, BG&E system LOCA pressure isolation valves on estimated the cost of implementing a sequences low-pressure injection lines, similar SAMA at Calvert Cliffs to be residual heat removal suction $2,300,000. Since the cost of lines, and high pressure implementing this SAMA exceeds the injection lines to increase the attainable benefit, this SAMA is not cost ability to detect an interfacing effective for ANO-2.

system LOCA.

CB-14 Increase Reduce the frequency of an 4.56% 35.87% $86,000 >$86,000 Not Cost Elimination of all core damage from frequency of interfacing system LOCA. Effective ISLOCA results in a benefit of $86,000 valve leak (analysis case ISLOCA). The cost of testing implementing this SAMA is judged to exceed the attainable benefit, even without a detailed cost estimate.

Therefore, this SAMA is not cost effective for ANO-2.

CB-19 Ensure all Scrub interfacing system 4.56% 35.87% $86,000 >>$86,000 Not Cost Elimination of all core damage from interfacing LOCA releases. One method Effective ISLOCA results in a benefit of $86,000 system LOCA would be to plug drains in the (analysis case ISLOCA). The cost of releases are break area so the break point implementing this SAMA is judged to scrubbed would be covered with water. exceed the attainable benefit, even without a detailed cost estimate.

Therefore, this SAMA is not cost effective for ANO-2.

ENHANCEMENTS RELATED TO IDENTIFYING OR COPING WITH CONTAINMENT BYPASS CB-20 Add redundant Enhance isolation valve 4.56% 35.87% $86,000 $1,000,000 Not Cost Elimination of all core damage from and diverse limit position indication, reducing Effective ISLOCA results in a benefit of $86,000 switch to each the frequency of containment (analysis case ISLOCA). In 1993, the containment isolation failure and cost of implementing a similar SAMA in isolation valve interfacing system LOCAs. the Westinghouse-CE System 80+ was estimated to be $1,000,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-40 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction CB-23 Develop Add a procedural 0.02% 0.04% $200 $35,000 Not Cost Elimination of all core damage enhanced requirement to close manual Effective attributable to plant damage state SBOu procedures for valve 2HPA-2 to ensure that results in a benefit of $200 (analysis case station blackout failure of 2SV-8231-2 will not CBPEN). At ANO-2, the cost of to prevent introduce a small modifying a plant procedure and the containment containment leak path. associated training is $35,000. Since the bypass cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

CB-26 Enhance plant Change plant operating 3.36% 26.40% $64,000 >$70,000 Not Cost Elimination of all human error associated procedures to procedures to isolate the low Effective with an interfacing system LOCA results improve credit pressure safety injection line in a benefit of $64,000 (analysis case for human action following the failure of series ISLOCAHEP). At ANO-2, the cost of to prevent and system check valves. Also, modifying a plant procedure and the cope with an enhance operator training on associated training is $35,000. Since interfacing coping with interfacing several systems are impacted, this system LOCA system LOCAs resulting from modification requires multiple procedure reactor coolant pump seal revisions. Implementation would also cooler tube ruptures. require increasing the inspection frequency for shutdown cooling suction line MOVs. As this SAMA requires multiple procedure modifications and in-service inspection costs, the cost of implementing this SAMA is >$70,000.

Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

ENHANCEMENTS RELATED TO CORE COOLING SYSTEMS CC-01 Provide Provide an extra water 100% 100% $632,000 >$632,000 Not Cost Elimination of all core damage results in a capability for source during sequences in Effective benefit of $632,000 (analysis case diesel-driven, which the reactor is MAXBENEFIT). The cost of low pressure depressurized and all other implementing this SAMA is judged to vessel makeup injection is unavailable (e.g., exceed the attainable benefit, even fire protection system). without a detailed cost estimate.

Therefore, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-41 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction CC-02 Provide an Reduce frequency of core 100% 100% $632,000 $5,000,000 Not Cost Elimination of all core damage results in a additional high melt from small LOCA Effective benefit of $632,000 (analysis case pressure sequences during station MAXBENEFIT). In 1998, BG&E injection pump blackout events. estimated the cost of implementing a with independent similar SAMA at Calvert Cliffs to be diesel $5,000,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

ENHANCEMENTS RELATED TO CORE COOLING SYSTEMS CC-07 Extend the Extend the reactor water 100% 100% $632,000 $1,000,000 Not Cost Elimination of all core damage results in a reactor water storage tank capacity in the Effective benefit of $632,000 (analysis case storage tank event of steam generator MAXBENEFIT). In 1993, the cost of source tube ruptures. Since the time implementing a similar SAMA in the available for recovery Westinghouse-CE System 80+ was depends mostly on the estimated to be $1,000,000. Since the refueling water storage tank cost of implementing this SAMA exceeds inventory, the ability to refill the attainable benefit, this SAMA is not the tank once it reaches a cost effective for ANO-2.

specified low level could prolong the cooling of the core for an indefinite period.

Steam generator tube leak rate would need to be decreased (i.e., through primary system depressurization) to less than the available refueling water storage tank makeup capacity.

Environmental Report Page E-42 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction CC-14 Replace two of Reduce the probability of 100% 100% $632,000 $2,000,000 Not Cost Elimination of all core damage results in a the four electric common cause failure of the Effective benefit of $632,000 (analysis case safety injection safety injection system. This MAXBENEFIT). In 1993, the cost of pumps with SAMA was originally implementing a similar SAMA in the diesel-powered intended for the Westinghouse-CE System 80+ was pumps Westinghouse-CE System estimated to be $2,000,000. Since the 80+, which has four trains of cost of implementing this SAMA exceeds safety injection. However, the attainable benefit, this SAMA is not the intent of this SAMA is to cost effective for ANO-2.

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

ENHANCEMENTS RELATED TO CORE COOLING SYSTEMS CC-18 Modify the Prevent plugging of the 7.54% 0.88% $36,000 >>$36,000 Not Cost Elimination of sump strainer plugging containment containment sump strainers Effective contribution to core damage results in a sump strainers by modifying the existing benefit of $36,000 (analysis case to prevent strainers and adding SUMPSTRAIN). The cost of plugging additional strainer area. implementing this SAMA is judged to exceed the attainable benefit, even without a detailed cost estimate.

Therefore, this SAMA is not cost effective for ANO-2.

CC-19 Provide an Reduce the potential for 5.45% 2.61% $29,000 >>$29,000 Not Cost Elimination of all core damage due to additional flow common cause failure of the Effective failure of the high-pressure safety path from the refueling water tank flow path injection flow path check valves results in refueling water check valves. a benefit of $27,000 (analysis case tank to the high- HPSICV). The cost of implementing this pressure safety SAMA is judged to exceed the attainable injection system benefit, even without a detailed cost through a estimate. Therefore, this SAMA is not diversified cost effective for ANO-2.

suction flow path check valve Environmental Report Page E-43 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction CC-20 Make Replace either containment 5.75% 2.75% $31,000 >$31,000 Not Cost Elimination of all core damage due to containment sump valve 2CV-5649-1 or Effective containment sump valve failures results sump 2CV-5650-2 with an air- in a benefit of $31,000 (analysis case recirculation operated valve. This would SUMPMOV). The cost of implementing outlet valve reduce the potential for this SAMA is judged to exceed the motor-operated common cause failure of attainable benefit, even without a detailed valves 2CV- these valves. cost estimate. Therefore, this SAMA is 5649-1 and not cost effective for ANO-2.

2CV-5650-2 diverse from one another ENHANCEMENTS RELATED TO CORE COOLING SYSTEMS CC-21 Provide actuator Reduce the potential for 4.06% 1.99% $22,000 >$22,000 Not Cost Elimination of all core damage due to diversity for the common cause failure of Effective common cause failure of the high-motor-operated high-pressure safety injection pressure safety injection valves results in valves in the motor-operated valves by a benefit of $21,000 (analysis case high-pressure replacing redundant train HPSIMOV). The cost of implementing safety injection valve actuators with this SAMA is judged to exceed the system diversified valve actuators. attainable benefit, even without a detailed cost estimate. Therefore, this SAMA is not cost effective for ANO-2.

CC-22 Incorporate Reduce the potential for 2.44% 2.01% $15,000 >$15,000 Not Cost Elimination of all core damage due to diversity among common cause failure of two Effective common cause failure of engineered recirculation or more recirculation safety features actuation and solid state actuation signal actuation signal and relays results in a benefit of $15,000 and engineered engineered safety features (analysis case ESFASRELAY). The cost safety features actuation signal actuation of implementing this SAMA is judged to actuation signal relays (e.g., K104A/B, SSR- exceed the attainable benefit, even actuation relays 1/3A, etc.) This modification without a detailed cost estimate.

would replace existing relays Therefore, this SAMA is not cost effective with relays of diverse design. for ANO-2.

Environmental Report Page E-44 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction CC-23 Provide an Increase the reliability of 0.97% 0.09% $5,000 >$5,000 Not Cost Elimination of all core damage due to additional automatic recirculation swap- Effective failure of the recirculation actuation signal recirculation over. This modification would level transmitters results in a benefit of actuation signal install an additional level $5,000 (analysis case RASLEVEL). The level transmitter transmitter and change the cost of implementing this SAMA is judged (2LT-5636-5) recirculation actuation logic to exceed the attainable benefit, even and change from 2-out-of-4 to 2-out-of-5. without a detailed cost estimate.

recirculation Therefore, this SAMA is not cost effective actuation logic for ANO-2.

from 2-out-of-4 to 2-out-of-5 ENHANCEMENTS RELATED TO CORE COOLING SYSTEMS CC-24 Provide bypass Provide a bypass flow path 0.91% 0.15% $4,000 >>$4,000 Not Cost Elimination of all core damage due to flow paths for all with a normally open motor- Effective failure of safety injection tank discharge safety injection operated control valve valves results in a benefit of $4,000 tanks around the safety injection (analysis case SIMOV). The cost of tank discharge control valves. implementing this SAMA is judged to This modification would exceed the attainable benefit, even increase the probability of without a detailed cost estimate.

injection if the motor- Therefore, this SAMA is not cost effective operated control valves fail for ANO-2.

closed.

ENHANCEMENTS RELATED TO LOSS OF COOLING WATER CW-01 Cap downstream Reduce the frequency of loss 19.99% 11.94% $112,000 >$112,000 Not Cost Elimination of all core damage due to loss piping of of component cooling water Effective of feedwater results in a benefit of normally closed initiating events, some of $112,000 (analysis case FDW). The cost component which are attributable to of implementing this SAMA is judged to cooling water catastrophic failure of one of exceed the attainable benefit, even drain and vent the m single isolation valves. without a detailed cost estimate.

valves Therefore, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-45 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction CW-06 On loss of Increase time before reactor 4.55% 2.74% $25,000 $35,000 Not Cost Perfectly reliable recovery of service essential raw coolant pump seal failure Effective water results in a benefit of $25,000 cooling water, during loss of service water (analysis case LOSWHEP). At ANO-2, proceduralize sequences. the cost of modifying a plant procedure shedding and the associated training is $35,000.

component Since the cost of implementing this cooling water SAMA exceeds the attainable benefit, this loads to extend SAMA is not cost effective for ANO-2.

the component cooling water heatup time ENHANCEMENTS RELATED TO LOSS OF COOLING WATER CW-07 Increase This SAMA was intended to 1.95% Not $12,000 >>$12,000 Not Cost Making the charging pumps perfectly charging pump improve the reliability of seal Estimated Effective reliable results in a benefit of $12,000 lube oil capacity cooling during normal (analysis case ATWS2). The cost of operation via seal injection. implementing this SAMA is judged to Although ANO-2 does not exceed the attainable benefit, even use seal injection for seal without a detailed cost estimate.

cooling during normal Therefore, this SAMA is not cost effective operation, the charging for ANO-2.

pumps have a risk significant function to add boron to the RCS in the event of an ATWS.

CW-09 Provide an Decrease the frequency of 32.16% 33.45% $202,000 >$202,000 Not Cost Elimination of all core damage due to loss additional core damage due to a loss of Effective of service water results in a benefit of diversified service water by installing an $202,000 (analysis case LOSW). The service water additional service water cost of implementing this SAMA is judged pump pump with an independent to exceed the attainable benefit, even diesel generator. This without a detailed cost estimate.

modification also requires Therefore, this SAMA is not cost effective that one of the remaining for ANO-2.

service water pumps be supplied with an independent diesel to reduce the potential for common cause failure of all of the service water pumps.

Environmental Report Page E-46 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO LOSS OF COOLING WATER CW-10 Create an Add redundant reactor 11.82% 10.71% $71,000 >>$71,000 Not Cost Elimination of all seal LOCAs results in a independent coolant pump seal cooling, Effective benefit of $71,000 (analysis case reactor coolant reducing the frequency of SEALLOCA). The cost of implementing pump seal core damage from loss of this SAMA is judged to exceed the injection system, component cooling water, attainable benefit, even without a detailed with dedicated service water, or station cost estimate. Therefore, this SAMA is diesel blackout. (Note: the not cost effective for ANO-2.

Westinghouse-CE System 80+ includes a dedicated, positive displacement seal injection pump (air-cooled) independent of component cooling water.)

CW-11 Create an Add redundant reactor 11.82% 10.71% $71,000 >>$71,000 Not Cost Elimination of all seal LOCAs results in a independent coolant pump seal cooling, Effective benefit of $71,000 (analysis case reactor coolant reducing the frequency of SEALLOCA). The cost of implementing pump seal core damage from loss of this SAMA is judged to exceed the injection system, component cooling water or attainable benefit, even without a detailed without service water, but not from a cost estimate. Therefore, this SAMA is dedicated diesel station blackout. not cost effective for ANO-2.

CW-13 Replace Eliminate emergency core 32.16% 33.45% $202,000 >$202,000 Not Cost Elimination of all core damage due to loss emergency core cooling system dependence Effective of service water results in a benefit of cooling system on service water. $202,000 (analysis case LOSW). The pump motors cost of implementing this SAMA is judged with air cooled to exceed the attainable benefit, even motors without a detailed cost estimate.

Therefore, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-47 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO LOSS OF COOLING WATER CW-14 Install improved Reactor coolant pump seal 11.82% 10.71% $71,000 $2,500,000 Not Cost Elimination of all seal LOCAs results in a reactor coolant O-rings constructed of Effective benefit of $71,000 (analysis case pump seals improved materials would SEALLOCA). In 1998, BG&E estimated reduce the likelihood of the cost of implementing a similar SAMA reactor coolant pump seal at Calvert Cliffs to be $2,500,000. Since LOCA. the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

CW-15 Install an Reduce the likelihood of loss 12.71% 11.47% $76,000 >>$76,000 Not Cost Elimination of all core damage due to loss additional of component cooling water Effective of the component cooling water system component leading to a reactor coolant results in a benefit of $76,000 (analysis cooling water pump seal LOCA. case LOCCW). The cost of implementing pump this SAMA is judged to exceed the attainable benefit, even without a detailed cost estimate. Therefore, this SAMA is not cost effective for ANO-2.

CW-21 Implement Improve the success rate of 4.55% 2.74% $25,000 $35,000 Not Cost Perfectly reliable recovery of service procedure and operator actions after support Effective water results in a benefit of $25,000 operator training system failures. (analysis case LOSWHEP). At ANO-2, enhancements the cost of modifying a plant procedure for support and the associated training is $35,000.

system failure Since the cost of implementing this sequences, with SAMA exceeds the attainable benefit, this an emphasis on SAMA is not cost effective for ANO-2.

anticipating problems and coping Environmental Report Page E-48 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO LOSS OF COOLING WATER CW-22 Improve ability to Reduce the chance of loss of 12.71% 11.47% $76,000 $565,000 Not Cost Elimination of all core damage due to loss cool residual decay heat removal by: (1) Effective of the component cooling water system heat removal modifying procedures and results in a benefit of $76,000 (analysis heat exchangers hardware to allow manual case LOCCW). In 1998, BG&E alignment of the fire estimated the cost of implementing a protection system to the similar SAMA at Calvert Cliffs to be component cooling water $565,000. Since the cost of system; or (2) installing a implementing this SAMA exceeds the component cooling water attainable benefit, this SAMA is not cost header cross-tie. effective for ANO-2.

CW-23 Develop Enhance loss of service 4.55% 2.74% $25,000 $35,000 Not Cost Perfectly reliable recovery of service enhanced water procedures to improve Effective water results in a benefit of $25,000 procedures for the ability to avoid (analysis case LOSWHEP). At ANO-2, loss of service unnecessary low pressure the cost of modifying a plant procedure water safety injection and and the associated training is $35,000.

containment spray pump Since the cost of implementing this overheating failures that can SAMA exceeds the attainable benefit, this minimize the benefit of SAMA is not cost effective for ANO-2.

restoring service water.

CW-24 Provide the Reduce the potential for a 11.82% 10.71% $71,000 >$71,000 Not Cost Elimination of all seal LOCAs results in a ability to seal LOCA following loss of Effective benefit of $71,000 (analysis case automatically trip component cooling water by SEALLOCA). The cost of implementing the reactor reducing reliance on operator this SAMA is judged to exceed the coolant pumps action to trip the reactor attainable benefit, even without a detailed on a loss of coolant pumps. cost estimate. Therefore, this SAMA is component not cost effective for ANO-2.

cooling water Environmental Report Page E-49 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO LOSS OF COOLING WATER CW-25 Add redundant Add a redundant valve in 1.62% 1.64% $10,000 >$10,000 Not Cost Elimination of all core damage due to control valve in series with 2CV-1530-1 on Effective service water to CCW isolation valve series with 2CV- service water header 1 (and failure results in a benefit of $10,000 1530-1 2CV-1531-2 on service water (analysis case SWMOV). The cost of header 2). This SAMA would implementing this SAMA is judged to increase the reliability of exceed the attainable benefit, even isolation if the isolation valves without a detailed cost estimate.

supplying the component Therefore, this SAMA is not cost effective cooling water heat for ANO-2.

exchangers and main chillers fail to close upon demand.

CW-26 Increase Reduce the failure frequency 16.17% 16.36% $100,000 >$100,000 Not Cost Elimination of all common cause failures inspections of of the service water system. Effective of service water pump discharge filters service water This SAMA would increase results in a benefit of $100,000 (analysis pump discharge the inspection and cleaning case FILTER). Currently, weekly filters frequency of the service cleaning of the service water strainer for water pump discharge filters, one pump requires about six hours.

reducing the probability of a Assuming $20/hour and bi-weekly common cause failure. cleaning for each strainer, the cost would be >$100,000 well before the end of the license renewal period. Therefore, this SAMA is not cost effective for ANO-2.

ENHANCEMENTS RELATED TO LOSS OF COOLING WATER CW-27 Replace current Reduce the failure frequency 16.17% 16.36% $100,000 >$200,000 Not Cost Elimination of all common cause failures service water of the service water system. Effective of service water pump discharge filters pump discharge This SAMA would install results in a benefit of $100,000 (analysis strainers with backwash filters in place of case FILTER). It was estimated that the backwash filters the existing strainers, material and installation of backwash reducing the probability of a filters for all three SW pumps would cost common cause failure. more than $79,000 (Reference E.2-6).

With engineering, documentation and training, the total cost would be more than $200,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-50 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO EX-VESSEL ACCIDENT MITIGATION OR CONTAINMENT PERFORMANCE EV-02 Install automatic Extend the time during which 0% 100% $178,000 $375,000 Not Cost Elimination of all off-site releases results containment water remains in the reactor Effective in a benefit of $178,000 (analysis case spray pump water storage tank, when full OFFSITE). In 1998, BG&E estimated the header throttle containment spray flow is not cost of implementing a similar SAMA at valves needed. Calvert Cliffs to be $375,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

EV-04 Develop an Provide a redundant source 0% 100% $178,000 $1,500,000 Not Cost Elimination of all off-site releases results enhanced of water to the containment to Effective in a benefit of $178,000 (analysis case drywell spray control containment pressure. OFFSITE). In 1993, the cost of system For a PWR, install a implementing a similar SAMA in the redundant containment spray Westinghouse-CE System 80+ was system. estimated to be $1,500,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

ENHANCEMENTS RELATED TO EX-VESSEL ACCIDENT MITIGATION OR CONTAINMENT PERFORMANCE EV-05 Provide a Similar to EV-04, except one 0% 100% $178,000 >>$178,000 Not Cost Elimination of all off-site releases results dedicated of the existing spray loops Effective in a benefit of $178,000 (analysis case drywell spray would be used instead of OFFSITE). The cost of implementing this system developing a new spray SAMA is judged to exceed the attainable system (i.e., new hardware, benefit, even without a detailed cost existing piping). In a PWR, estimate. Therefore, this SAMA is not develop a dedicated cost effective for ANO-2.

containment spray system.

EV-07 Install a filtered Assuming injection is 0% 100% $178,000 $5,700,000 Not Cost Elimination of all off-site releases results containment available (non-ATWS Effective in a benefit of $178,000 (analysis case vent sequences), provide alternate OFFSITE). In 1998, BG&E estimated the decay heat removal and cost of implementing a similar SAMA at fission products scrubbing. Calvert Cliffs to be $5,700,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-51 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction EV-08 Install an Provide an alternate decay 0% 100% $178,000 $3,100,000 Not Cost Elimination of all off-site releases results unfiltered heat removal method (non- Effective in a benefit of $178,000 (analysis case containment ATWS) without fission OFFSITE). In 1998, BG&E estimated the vent product scrubbing. cost of implementing a similar SAMA at Calvert Cliffs to be $3,100,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

EV-09 Create/enhance Reduce hydrogen detonation 0% 100% $178,000 $1,000,000 Not Cost Elimination of all off-site releases results hydrogen control using either a new, Effective in a benefit of $178,000 (analysis case system with independent power supply; a OFFSITE). In 1993, the cost of independent non-safety grade portable implementing a similar SAMA in the power supply generator; existing station Westinghouse-CE System 80+ was batteries; or existing AC/DC estimated to be $1,000,000. Since the independent power supplies, cost of implementing this SAMA exceeds such as the security system the attainable benefit, this SAMA is not diesel. cost effective for ANO-2.

ENHANCEMENTS RELATED TO EX-VESSEL ACCIDENT MITIGATION OR CONTAINMENT PERFORMANCE EV-10 Create a passive Reduce hydrogen detonation 0% 100% $178,000 $800,000 Not Cost Elimination of all off-site releases results hydrogen control potential without requiring Effective in a benefit of $178,000 (analysis case system electric power. OFFSITE). In 1993, the cost of implementing a similar SAMA in the Westinghouse-CE System 80+ was estimated to be $800,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

EV-11 Create a Provide a ceramic-lined 0% 100% $178,000 $108,000,000 Not Cost Elimination of all off-site releases results refractory-lined concrete crucible and cooling Effective in a benefit of $178,000 (analysis case crucible with system in the reactor cavity. OFFSITE). In 1993, the cost of heat removal A molten core escaping from implementing a similar SAMA in the potential under the vessel would be Westinghouse-CE System 80+ was the basemat to contained within the crucible. estimated to be $108,000,000. Since the contain molten Water cooling of the cruc ble cost of implementing this SAMA exceeds debris would cool the molten core, the attainable benefit, this SAMA is not preventing melt-through. cost effective for ANO-2.

Environmental Report Page E-52 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction EV-12 Create a water Provide a bed of refractory 0% 100% $178,000 $19,000,000 Not Cost Elimination of all off-site releases results cooled rubble pebbles to impede the flow of Effective in a benefit of $178,000 (analysis case bed on the molten corium to the concrete OFFSITE). In 1993, the cost of pedestal drywell structures and implementing a similar SAMA in the increase the available heat Westinghouse-CE System 80+ was transfer area. estimated to be $19,000,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

ENHANCEMENTS RELATED TO EX-VESSEL ACCIDENT MITIGATION OR CONTAINMENT PERFORMANCE EV-15 Create a reactor Enhance the ability to cool 1.48% 5.36% $17,000 $8,750,000 Not Cost Elimination of core damage attributable to cavity flooding debris, reduce core-concrete Effective plant damage state IVKi results in a system interaction, and provide benefit of $17,000 (analysis case fission product scrubbing. CAVITY). In 1999, the cost of implementing a similar SAMA at ANO-1 was estimated to be $8,750,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

EV-16 Creating other Drill pathways in the reactor 1.48% 5.36% $17,000 >>$17,000 Not Cost Elimination of core damage attributable to options for vessel support structure to Effective plant damage state IVKi results in a reactor cavity allow drainage from the benefit of $17,000 (analysis case flooding (Option steam generator CAVITY). The cost of implementing this

1) compartments, refueling SAMA is judged to exceed the attainable canal, sumps, etc., to flood benefit, even without a detailed cost the reactor cavity. Also (for estimate. Therefore, this SAMA is not ice condensers), allow cost effective for ANO-2.

drainage of water from melted ice into the reactor cavity. This SAMA would enhance the ability to cool debris, reduce core-concrete interaction, and provide fission product scrubbing.

Environmental Report Page E-53 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction EV-17 Creating other Flood the reactor cavity via 1.48% 5.36% $17,000 >>$17,000 Not Cost Elimination of core damage attributable to options for systems l ke the diesel-driven Effective plant damage state IVKi results in a reactor cavity fire pumps to enhance the benefit of $17,000 (analysis case flooding (Option ability to cool debris, reduce CAVITY). The cost of implementing this

2) core concrete interaction, and SAMA is judged to exceed the attainable provide fission product benefit, even without a detailed cost scrubbing. estimate. Therefore, this SAMA is not cost effective for ANO-2.

ENHANCEMENTS RELATED TO EX-VESSEL ACCIDENT MITIGATION OR CONTAINMENT PERFORMANCE EV-19 Provide a core Prevent direct core debris 0% 100% $178,000 $45,000,000 Not Cost Elimination of all off-site releases results debris control attack of the primary Effective in a benefit of $178,000 (analysis case system containment steel shell by OFFSITE). In 1998, BG&E estimated the erecting a barrier to protect cost of implementing a similar SAMA at the containment walls from Calvert Cliffs to be $45,000,000. Since ejected core debris following the cost of implementing this SAMA a core melt scenario at high exceeds the attainable benefit, this SAMA pressure. is not cost effective for ANO-2.

EV-21 Provide Prevent combustion of 0% 100% $178,000 $10,900,000 Not Cost Elimination of all off-site releases results containment hydrogen and carbon Effective in a benefit of $178,000 (analysis case inerting monoxide gases. OFFSITE). In 1999, the cost of capability implementing a similar SAMA at ANO-1 was estimated to be $10,900,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

EV-22 Use fire water Provide a redundant 0% 100% $178,000 $565,000 Not Cost Elimination of all off-site releases results spray pump for containment spray method. Effective in a benefit of $178,000 (analysis case containment OFFSITE). In 1998, BG&E estimated the spray cost of implementing a similar SAMA at Calvert Cliffs to be $565,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-54 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction EV-23 Install a passive Provide containment spray 0% 100% $178,000 >>$178,000 Not Cost Elimination of all off-site releases results containment with very high reliability and Effective in a benefit of $178,000 (analysis case spray system without support systems. OFFSITE). The cost of implementing this SAMA is judged to exceed the attainable benefit, even without a detailed cost estimate. Therefore, this SAMA is not cost effective for ANO-2.

ENHANCEMENTS RELATED TO EX-VESSEL ACCIDENT MITIGATION OR CONTAINMENT PERFORMANCE EV-25 Increase Reduce the chance of 0% 100% $178,000 >>$178,000 Not Cost Elimination of all off-site releases results containment containment overpressure. Effective in a benefit of $178,000 (analysis case design pressure OFFSITE). The cost of implementing this SAMA is judged to exceed the attainable benefit, even without a detailed cost estimate. Therefore, this SAMA is not cost effective for ANO-2.

EV-26 Provide an Use an advanced concrete 0% 100% $178,000 $5,000,000 Not Cost Elimination of all off-site releases results alternative composition in the reactor Effective in a benefit of $178,000 (analysis case concrete cavity or increase the OFFSITE). In 1993, the cost of composition in thickness of the concrete implementing a similar SAMA in the the reactor basemat to prevent basemat Westinghouse-CE System 80+ was cavity melt-through. estimated to be $5,000,000. Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

EV-27 Provide a Modify the reactor cavity 0% 100% $178,000 $2,500,000 Not Cost Elimination of all off-site releases results reactor vessel configuration to externally Effective in a benefit of $178,000 (analysis case exterior cooling cool the lower head of the OFFSITE). In 1993, the cost of system reactor vessel following a implementing a similar SAMA in the core melt accident. This Westinghouse-CE System 80+ was SAMA has the potential to estimated to be $2,500,000. Since the cool a molten core before it cost of implementing this SAMA exceeds causes vessel failure. the attainable benefit, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-55 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction EV-28 Create a Provide a separate building 0% 100% $178,000 >>$178,000 Not Cost Elimination of all off-site releases results vacuum building maintained at vacuum to Effective in a benefit of $178,000 (analysis case connect to the primary OFFSITE). The cost of implementing this containment following an SAMA is judged to exceed the attainable accident, thereby benefit, even without a detailed cost depressurizing the primary estimate. Therefore, this SAMA is not containment and further cost effective for ANO-2.

reducing emissions from severe accidents.

ENHANCEMENTS RELATED TO EX-VESSEL ACCIDENT MITIGATION OR CONTAINMENT PERFORMANCE EV-29 Add ribbing to Reduce the potential for 0% 100% $178,000 >>$178,000 Not Cost Elimination of all off-site releases results the containment buckling of the containment Effective in a benefit of $178,000 (analysis case shell shell due to vacuum OFFSITE). The cost of implementing this conditions (i.e., reverse SAMA is judged to exceed the attainable pressure loadings). benefit, even without a detailed cost estimate. Therefore, this SAMA is not cost effective for ANO-2.

EV-30 Provide actuator Reduce the potential for 6.97% 3.81% $38,000 >$38,000 Not Cost Elimination of all core damage due to diversity for common cause failure of Effective common cause failure of containment motor-operated containment spray system spray valves results in a benefit of valves in the motor-operated valves by $38,000 (analysis case SPRAYMOV).

containment replacing redundant train The cost of implementing this SAMA is spray system motor-operated valve judged to exceed the attainable benefit, actuators with diverse valve even without a detailed cost estimate.

actuators. Therefore, this SAMA is not cost effective for ANO-2.

EV-31 Remove reactor Remove check valve 1.48% 5.36% $17,000 >$17,000 Not Cost Elimination of core damage attributable to vessel cavity internals to improve the Effective plant damage state IVKi results in a check valve potential for cooling benefit of $17,000 (analysis case 2BS-46 internals communication between CAVITY). The cost of implementing this molten core debris in the SAMA is judged to exceed the attainable bottom of the cavity and benefit, even without a detailed cost water on the containment estimate. Therefore, this SAMA is not floor. Improved cooling of a cost effective for ANO-2.

failed core would decrease the potential for a post severe accident off-site release.

Environmental Report Page E-56 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO FEEDWATER OR FEED AND BLEED RELIABILITY OR AVAILIABILITY FW-01 Install a digital Reduce the likelihood of loss 19.99% 11.94% $112,000 >$112,000 Not Cost Elimination of all core damage due to loss feedwater of main feedwater following a Effective of feedwater results in a benefit of upgrade plant trip. $112,000 (analysis case FDW). The cost of implementing this SAMA is judged to exceed the attainable benefit, even without a detailed cost estimate.

Therefore, this SAMA is not cost effective for ANO-2.

FW-08 Provide hookup Temporary connections could 0.91% 0.29% $5,000 >>$5,000 Not Cost Elimination of turbine-driven pump for portable allow portable generators to Effective dependence on DC power results in a generators power the turbine-driven benefit of $5,000 (analysis case auxiliary feedwater pump TDPUMPDC). The cost of implementing controls after station batteries this SAMA is judged to exceed the are depleted. attainable benefit, even without a detailed cost estimate. Therefore, this SAMA is not cost effective for ANO-2.

FW-13 Install an Allow continuous makeup to 17.79% 12.51% $104,000 $271,000 Not Cost A perfectly reliable EFW system results in independent the condensate storage tank Effective a benefit of $104,000 (analysis case diesel for the during a station blackout EFW). In 1998, BG&E estimated the cost condensate event. of implementing a similar SAMA at storage tank Calvert Cliffs to be $271,000. Since the makeup pumps cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

FW-15 Create passive Provide a passive, 100% 100% $632,000 >$632,000 Not Cost Elimination of all core damage results in a secondary side secondary-side heat-rejection Effective benefit of $632,000 (analysis case coolers loop consisting of a MAXBENEFIT). The cost of condenser and heat sink to implementing this SAMA is judged to reduce the potential for core exceed the attainable benefit, even damage due to loss-of- without a detailed cost estimate.

feedwater events. Therefore, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-57 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO FEEDWATER OR FEED AND BLEED RELIABILITY OR AVAILIABILITY FW-17 Enhance Enhance emergency 3.42% 0.75% $17,000 $35,000 Not Cost Elimination of operator failure to open the emergency operating procedures to Effective emergency feedwater flow control valves feedwater flow place emergency feedwater results in a benefit of $17,000 (analysis control in the flow control valves in an open case EFWCV). At ANO-2, the cost of emergency position once it has been modifying a plant procedure and the operating determined that main steam associated training is $35,000. Since the procedures isolation signal conditions do cost of implementing this SAMA exceeds not exist. If the outboard flow the attainable benefit, this SAMA is not control valves from both the cost effective for ANO-2.

motor-driven and turbine-driven were in a full open position upon loss of power supply, the potential for loss of flow to both steam generators would be minimized.

FW-18 Replace current Remove potential for 100% 100% $632,000 $2,700,000 Not Cost Elimination of all core damage results in a pilot operated common cause failure of the Effective benefit of $632,000 (analysis case relief valves with pilot operated relief valves by MAXBENEFIT). In 1998, BG&E larger ones such replacing them with larger estimated the cost of implementing a that only one is ones, such that only one is similar SAMA at Calvert Cliffs to be required for required. $2,700,000. Since the cost of successful feed implementing this SAMA exceeds the and bleed attainable benefit, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-58 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO FEEDWATER OR FEED AND BLEED RELIABILITY OR AVAILIABILITY FW-19 Create ability to Create the ability to 1.79% 1.29% $10,000 >>$10,000 Not Cost Perfectly reliable re-alignment of automatically automatically align Effective EFW/AFW suction to the alternate align emergency emergency condensate storage tank results in a feedwater/auxilia feedwater/auxiliary feedwater benefit of $10,000 (analysis case CST).

ry feedwater suction to the other The cost of implementing this SAMA is suction to the condensate storage tank on judged to exceed the attainable benefit, other low-low level of 2T-41A or even without a detailed cost estimate.

condensate 2T-41B. This modification Therefore, this SAMA is not cost effective storage tank on would reduce the potential for for ANO-2.

low-low level of a loss of feedwater.

2T-41A or 2T-41B ENHANCEMENTS RELATED TO HEATING, VENTILATION AND AIR CONDITIONING HV-03 Develop Reduce probability of failure 27.48% 29.73% $174,000 >$300,000 Not Cost Perfectly reliable shutdown heat enhanced of HVAC recovery actions Beneficial exchanger room cooling results in a procedures for through the use of temporary benefit of $174,000 (analysis case temporary HVAC equipment to cool both HVAC). This SAMA requires a 60-ton, shutdown heat-exchanger temporary industrial coolers for each of rooms following a loss of two the shutdown heat exchanger rooms.

out of three room unit coolers The cooler should include a control in each room. system, an independent power source and a heat sink other than service water.

The equipment must be maintained on-site and inspected/tested regularly for the duration of plant life. Operator training to stage the temporary coolers for appropriate use would also be required.

One temporary cooling unit, diesel generator, control system and cooling water interface would cost over $150,000.

As this SAMA requires two units, the minimum cost associated with implementation of this SAMA is >$300K.

Since the cost of implementing this SAMA exceeds the attainable benefit, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-59 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction ENHANCEMENTS RELATED TO HEATING, VENTILATION AND AIR CONDITIONING HV-05 Create ability to Allow continued fan operation 17.79% 12.51% $104,00 $226,000 Not Cost A perfectly reliable EFW system results in switch fan power in a station blackout. (This Effective a benefit of $104,000 (analysis case supply to station SAMA was created for a EFW). In 1998, BG&E estimated the cost batteries in a BWR reactor core isolation of implementing a similar SAMA at station blackout cooling room at the James A. Calvert Cliffs to be $226,000. Since the Fitzpatrick Nuclear Power cost of implementing this SAMA exceeds Plant. However, a similar the attainable benefit, this SAMA is not SAMA may be applied to cost effective for ANO-2.

ANO-2's emergency feedwater room.)

ENHANCEMENTS RELATED TO INSTRUMENT AIR IA-02 Replace current Improve reliability and ~0% ~0% "minimal" >>minimal Not Cost Perfectly reliable air compressors result air compressors increase availability of Effective in minimal benefit (analysis case AIR).

with more instrument air compressors. The cost of implementing this SAMA is reliable models judged to exceed the attainable benefit, even without a detailed cost estimate.

Therefore, this SAMA is not cost effective for ANO-2.

OTHER ENHANCEMENTS OT-02 Create a reactor Primary system 100% 100% $632,000 $4,600,000 Not Cost Elimination of all core damage results in a coolant depressurization would allow Effective benefit of $632,000 (analysis case depressurization low pressure emergency core MAXBENEFIT). In 1999, the cost of system cooling system injection in implementing a similar SAMA at ANO-1 the event of small LOCA and was estimated to be $4,600,000. Since high-pressure safety injection the cost of implementing this SAMA failure. Even if core damage exceeds the attainable benefit, this SAMA is not prevented, low primary is not cost effective for ANO-2.

system pressure alleviates some concerns about high pressure melt ejection.

Modification could install a new depressurization system or utilize existing pilot-operated relief valves, head vents and secondary side valves.

Environmental Report Page E-60 Arkansas Nuclear One - Unit 2

Table E.2-1, Summary of SAMA Candidates Considered in Cost-Benefit Evaluation (continued)

CDF Off-site SAMA Potential Estimated Estimated Discussion Reduc- Dose Conclusion Basis for Conclusion ID Enhancement Benefit Cost tion Reduction OT-06 Install secondary Prevent secondary side 100% 100% $632,000 $1,100,000 Not Cost Elimination of all core damage results in a side guard pipes depressurization if a steam Effective benefit of $632,000 (analysis case up to the main line break occurs upstream of MAXBENEFIT). In 1993, the cost of steam isolation the main steam isolation implementing a similar SAMA in the valves valves. This SAMA also Westinghouse-CE System 80+ was prevents consequential estimated to be $1,100,000. Since the multiple steam generator cost of implementing this SAMA exceeds tube ruptures following a the attainable benefit, this SAMA is not main steam line break event. cost effective for ANO-2.

OT-07 Provide digital Installation digital large break 4.03% 3.49% $24,000 >>$24,000 Not Cost Elimination of all core damage due to large break LOCA early detection Effective large LOCAs results in a benefit of LOCA protection instrumentation to improve $24,000 (analysis case LBLOCA). The the ability to identify cost of implementing this SAMA is judged precursors of a large break to exceed the attainable benefit, even LOCA (i.e., a leak before without a detailed cost estimate.

break). Therefore, this SAMA is not cost effective for ANO-2.

Environmental Report Page E-61 Arkansas Nuclear One - Unit 2

Table E.2-2, Sensitivity Analysis Results Estimated Estimated Estimated Estimated Estimated Estimated SAMA Estimated Potential Enhancement Benefit Benefit Benefit Benefit Benefit Benefit ID Cost (baseline) (Sensitivity 1) (Sensitivity 2) (Sensitivity 3) (Sensitivity 4) (Sensitivity 5)

AC/DC Install a combustion turbine $39,000 $3,350,000 $27,000 $42,000 $17,000 $39,000 $43,000

-02 generator AC/DC Use fuel cells in lieu of conventional $34,000 $2,000,000 $23,000 $37,000 $15,000 $35,000 $38,000

-04 lead-acid batteries AC/DC Provide additional DC battery $34,000 >$150,000 $23,000 $37,000 $15,000 $35,000 $38,000

-05 capability AC/DC Train operations crew for response to $5,000 $35,000 $3,000 $5,000 $2,000 $5,000 $5,000

-06 inadvertent actuation signals AC/DC Improve bus cross-tie capability $39,000 $1,119,000 $27,000 $42,000 $17,000 $39,000 $43,000

-09 AC/DC Incorporate alternate battery $34,000 $134,000 $23,000 $37,000 $15,000 $35,000 $38,000

-10 charging capabilities AC/DC Replace current station batteries with $34,000 >$150,000 $23,000 $37,000 $15,000 $35,000 $38,000

-12 a more reliable model AC/DC Create AC power cross tie capability $39,000 >>$39,000 $27,000 $42,000 $17,000 $39,000 $43,000

-13 across units at a multi-unit site AC/DC Develop enhanced procedures to $6,000 $35,000 $4,000 $6,000 $3,000 $6,000 $7,000

-15 repair or change out failed 4KV breakers AC/DC Emphasize steps in plant recovery $34,000 $35,000 $24,000 $37,000 $15,000 $34,000 $38,000

-16 following a station blackout event AC/DC Create a back-up source for diesel $20,000 $1,700,000 $14,000 $22,000 $9,000 $20,000 $22,000

-19 cooling AC/DC Use fire protection systems as a $39,000 >$497, 000 $27,000 $42,000 $17,000 $39,000 $43,000

-20 backup for diesel cooling AC/DC Provide a connection to an alternate $39,000 >$25,000,000 $27,000 $42,000 $17,000 $39,000 $43,000

-21 off-site power source AC/DC Implement underground off-site $39,000 >$25,000,000 $27,000 $42,000 $17,000 $39,000 $43,000

-22 power lines Environmental Report Page E-62 Arkansas Nuclear One - Unit 2

Table E.2-2, Sensitivity Analysis Result (continued)

Estimated Estimated Estimated Estimated Estimated Estimated SAMA Potential Enhancement Benefit Estimated Cost Benefit Benefit Benefit Benefit Benefit ID (baseline) (Sensitivity 1) (Sensitivity 2) (Sensitivity 3) (Sensitivity 4) (Sensitivity 5)

AC/DC Create the ability to automatically $34,000 >>$34,000 $23,000 $37,000 $15,000 $35,000 $38,000

-24 transfer battery charger/eliminator 2D31B to an alternate power source AT-01 Provide alternative ATWS pressure $140,000 $1,000,000 $96,000 $151,000 $62,000 $140,000 $154,000 relief valves AT-02 Create a boron injection/shutdown $140,000 $300,000 $96,000 $151,000 $62,000 $140,000 $154,000 system to backup the mechanical control rods AT-03 Provide a diverse plant protection $140,000 $3,000,000 $96,000 $151,000 $62,000 $140,000 $154,000 system CB-01 Institute a maintenance practice to $25,000 $1,500,000 $21,000 $29,000 $12,000 $25,000 $26,000 perform a 100% inspection of steam generator tubes during each refueling outage CB-03 Increase the pressure capacity of the $25,000 >>$25,000 $21,000 $29,000 $12,000 $25,000 $26,000 secondary side CB-04 Install a redundant spray system to $25,000 $5,000,000 $21,000 $29,000 $12,000 $25,000 $26,000 depressurize the primary system during a steam generator tube rupture CB-07 Provide main steam safety valve and $178,000 $9,500,000 $178,000 $226,000 $91,000 $178,000 $178,000 automatic depressurization valve scrubbing CB-08 Provide additional steam generator $25,000 >>$25,000 $21,000 $29,000 $12,000 $25,000 $26,000 tube rupture coping features CB-10 Direct steam generator flooding after $25,000 $35,000 $21,000 $29,000 $12,000 $25,000 $26,000 a steam generator tube rupture, prior to core damage CB-13 Install additional instrumentation for $86,000 $2,300,000 $78,000 $104,000 $42,000 $87,000 $90,000 interfacing system LOCA sequences CB-14 Increase frequency of valve leak $86,000 >$86,000 $78,000 $104,000 $42,000 $87,000 $90,000 testing CB-19 Ensure all interfacing system LOCA $86,000 >>$86,000 $78,000 $104,000 $42,000 $87,000 $90,000 releases are scrubbed Environmental Report Page E-63 Arkansas Nuclear One - Unit 2

Table E.2-2, Sensitivity Analysis Result (continued)

Estimated Estimated Estimated Estimated Estimated Estimated SAMA Potential Enhancement Benefit Estimated Cost Benefit Benefit Benefit Benefit Benefit ID (baseline) (Sensitivity 1) (Sensitivity 2) (Sensitivity 3) (Sensitivity 4) (Sensitivity 5)

CB-20 Add redundant and diverse limit $86,000 $1,000,000 $78,000 $104,000 $42,000 $87,000 $90,000 switch to each containment isolation valve CB-23 Develop enhanced procedures for $200 $35,000 $100 $200 $100 $200 $200 station blackout to prevent containment bypass CB-26 Enhance plant procedures to $64,000 >$70,000 $57,000 $77,000 $31,000 $64,000 $66,000 improve credit for human action to prevent and cope with an interfacing system LOCA CC-01 Provide capability for diesel-driven, $632,000 >$632,000 $436,000 $686,000 $282,000 $638,000 $699,000 low pressure vessel makeup CC-02 Provide an additional high pressure $5,000,000 $436,000 $686,000 $282,000 $638,000 $699,000 injection pump with independent diesel CC-07 Extend the reactor water storage $632,000 $1,000,000 $436,000 $686,000 $282,000 $638,000 $699,000 tank source CC-14 Replace two of the four electric $632,000 $2,000,000 $436,000 $686,000 $282,000 $638,000 $699,000 safety injection pumps with diesel-powered pumps CC-18 Modify the containment sump $36,000 >>$36,000 $21,000 $37,000 $15,000 $36,000 $41,000 strainers to prevent plugging CC-19 Provide an additional flow path from $29,000 >>$29,000 $19,000 $31,000 $13,000 $30,000 $33,000 the refueling water tank to the high-pressure safety injection system through a diversified suction flow path check valve CC-20 Make containment sump recirculation $31,000 >$31,000 $20,000 $33,000 $14,000 $32,000 $35,000 outlet valve motor-operated valves 2CV-5649-1 and 2CV-5650-2 diverse from one another CC-21 Provide actuator diversity for the $22,000 >$22,000 $14,000 $23,000 $10,000 $22,000 $25,000 motor-operated valves in the high-pressure safety injection system Environmental Report Page E-64 Arkansas Nuclear One - Unit 2

Table E.2-2, Sensitivity Analysis Result (continued)

Estimated Estimated Estimated Estimated Estimated Estimated SAMA Potential Enhancement Benefit Estimated Cost Benefit Benefit Benefit Benefit Benefit ID (baseline) (Sensitivity 1) (Sensitivity 2) (Sensitivity 3) (Sensitivity 4) (Sensitivity 5)

CC-22 Incorporate diversity among $15,000 >$15,000 $10,000 $16,000 $7,000 $15,000 $17,000 recirculation actuation signal and engineered safety features actuation signal actuation relays CC-23 Provide an additional recirculation $5,000 >$5,000 $3,000 $5,000 $2,000 $5,000 $5,000 actuation signal level transmitter (2LT-5636-5) and change recirculation actuation logic from 2-out-of-4 to 2-out-of-5 CC-24 Provide bypass flow paths for all $4,000 >>$4,000 $3,000 $4,000 $2,000 $4,000 $5,000 safety injection tanks CW-01 Cap downstream piping of normally $112,000 >$112,000 $73,000 $119,000 $49,000 $113,000 $125,000 closed component cooling water drain and vent valves CW-06 On loss of essential raw cooling $25,000 $35,000 $16,000 $27,000 $11,000 $26,000 $28,000 water, proceduralize shedding component cooling water loads to extend the component cooling water heatup time CW-07 Increase charging pump lube oil $12,000 >>$12,000 $9,000 $14,000 $6,000 $13,000 $14,000 capacity CW-09 Provide an additional diversified $202,000 >$202,000 $139,000 $219,000 $90,000 $204,000 $224,000 service water pump CW-10 Create an independent reactor $71,000 >>$71,000 $48,000 $76,000 $31,000 $72,000 $79,000 coolant pump seal injection system, with dedicated diesel CW-11 Create an independent reactor $71,000 >>$71,000 $48,000 $76,000 $31,000 $72,000 $79,000 coolant pump seal injection system, without dedicated diesel CW-13 Replace emergency core cooling $202,000 >$202,000 $139,000 $219,000 $90,000 $204,000 $224,000 system pump motors with air cooled motors CW-14 Install improved reactor coolant $71,000 $2,500,000 $48,000 $76,000 $31,000 $72,000 $79,000 pump seals Environmental Report Page E-65 Arkansas Nuclear One - Unit 2

Table E.2-2, Sensitivity Analysis Result (continued)

Estimated Estimated Estimated Estimated Estimated Estimated SAMA Potential Enhancement Benefit Estimated Cost Benefit Benefit Benefit Benefit Benefit ID (baseline) (Sensitivity 1) (Sensitivity 2) (Sensitivity 3) (Sensitivity 4) (Sensitivity 5)

CW-15 Install an additional component $76,000 >>$76,000 $51,000 $82,000 $34,000 $77,000 $85,000 cooling water pump CW-21 Implement procedure and operator $25,000 $35,000 $16,000 $27,000 $11,000 $26,000 $28,000 training enhancements for support system failure sequences, with an emphasis on anticipating problems and coping CW-22 Improve ability to cool residual heat $76,000 $565,000 $51,000 $82,000 $34,000 $77,000 $85,000 removal heat exchangers CW-23 Develop enhanced procedures for $25,000 $35,000 $16,000 $27,000 $11,000 $26,000 $28,000 loss of service water CW-24 Provide the ability to automatically $71,000 >$71,000 $48,000 $76,000 $31,000 $72,000 $79,000 trip the reactor coolant pumps on a loss of component cooling water CW-25 Add redundant control valve in series $10,000 >$10,000 $7,000 $11,000 $4,000 $10,000 $11,000 with 2CV-1530-1 CW-26 Increase inspections of service water $100,000 >$100,000 $68,000 $108,000 $44,000 $101,000 $111,000 pump discharge filters CW-27 Replace current service water pump $100,000 >$200,000 $68,000 $108,000 $44,000 $101,000 $111,000 discharge strainers with backwash filters EV-02 Install automatic containment spray $178,000 $375,000 $178,000 $226,000 $91,000 $178,000 $178,000 pump header throttle valves EV-04 Develop an enhanced drywell spray $178,000 $1,500,000 $178,000 $226,000 $91,000 $178,000 $178,000 system EV-05 Provide a dedicated drywell spray $178,000 >>$178,000 $178,000 $226,000 $91,000 $178,000 $178,000 system EV-07 Install a filtered containment vent $178,000 $5,700,000 $178,000 $226,000 $91,000 $178,000 $178,000 EV-08 Install an unfiltered containment vent $178,000 $3,100,000 $178,000 $226,000 $91,000 $178,000 $178,000 EV-09 Create/enhance hydrogen control $178,000 $1,000,000 $178,000 $226,000 $91,000 $178,000 $178,000 system with independent power supply Environmental Report Page E-66 Arkansas Nuclear One - Unit 2

Table E.2-2, Sensitivity Analysis Result (continued)

Estimated Estimated Estimated Estimated Estimated Estimated SAMA Potential Enhancement Benefit Estimated Cost Benefit Benefit Benefit Benefit Benefit ID (baseline) (Sensitivity 1) (Sensitivity 2) (Sensitivity 3) (Sensitivity 4) (Sensitivity 5)

EV-10 Create a passive hydrogen control $178,000 $800,000 $178,000 $226,000 $91,000 $178,000 $178,000 system EV-11 Create a refractory-lined crucible with $178,000 $108,000,000 $178,000 $226,000 $91,000 $178,000 $178,000 heat removal potential under the basemat to contain molten debris EV-12 Create a water cooled rubble bed on $178,000 $19,000,000 $178,000 $226,000 $91,000 $178,000 $178,000 the pedestal EV-15 Create a reactor cavity flooding $17,000 $8,750,000 $14,000 $20,000 $8,000 $17,000 $18,000 system EV-16 Creating other options for reactor $17,000 >>$17,000 $14,000 $20,000 $8,000 $17,000 $18,000 cavity flooding (Option 1)

EV-17 Creating other options for reactor $17,000 >>$17,000 $14,000 $20,000 $8,000 $17,000 $18,000 cavity flooding (Option 2)

EV-19 Provide a core debris control system $178,000 $45,000,000 $178,000 $226,000 $91,000 $178,000 $178,000 EV-20 Create a core melt source reduction $178,000 >>$178,000 $178,000 $226,000 $91,000 $178,000 $178,000 system (COMSORS)

EV-21 Provide containment inerting $178,000 $10,900,000 $178,000 $226,000 $91,000 $178,000 $178,000 capability EV-22 Use fire water spray pump for $178,000 $565,000 $178,000 $226,000 $91,000 $178,000 $178,000 containment spray EV-23 Install a passive containment spray $178,000 >>$178,000 $178,000 $226,000 $91,000 $178,000 $178,000 system EV-25 Increase containment design $178,000 >>$178,000 $178,000 $226,000 $91,000 $178,000 $178,000 pressure EV-26 Provide an alternative concrete $178,000 $5,000,000 $178,000 $226,000 $91,000 $178,000 $178,000 composition in the reactor cavity EV-27 Provide a reactor vessel exterior $178,000 $2,500,000 $178,000 $226,000 $91,000 $178,000 $178,000 cooling system EV-28 Create a vacuum building $178,000 >>$178,000 $178,000 $226,000 $91,000 $178,000 $178,000 EV-29 Add ribbing to the containment shell $178,000 >>$178,000 $178,000 $226,000 $91,000 $178,000 $178,000 Environmental Report Page E-67 Arkansas Nuclear One - Unit 2

Table E.2-2, Sensitivity Analysis Result (continued)

Estimated Estimated Estimated Estimated Estimated Estimated SAMA Potential Enhancement Benefit Estimated Cost Benefit Benefit Benefit Benefit Benefit ID (baseline) (Sensitivity 1) (Sensitivity 2) (Sensitivity 3) (Sensitivity 4) (Sensitivity 5)

EV-30 Provide actuator diversity for motor- $38,000 >$38,000 $25,000 $40,000 $17,000 $38,000 $42,000 operated valves in the containment spray system EV-31 Remove reactor vessel cavity check $17,000 >$17,000 $14,000 $20,000 $8,000 $17,000 $18,000 valve 2BS-46 internals FW-01 Install a digital feedwater upgrade $112,000 >$112,000 $73,000 $119,000 $49,000 $113,000 $125,000 FW-08 Provide hookup for portable $5,000 >>$5,000 $3000 $5,000 $2,000 $5,000 $5,000 generators FW-13 Install an independent diesel for the $104,000 $271,000 $69,000 $111,000 $46,000 $105,000 $116,000 condensate storage tank makeup pumps FW-15 Create passive secondary side $632,000 >$632,000 $436,000 $686,000 $282,000 $638,000 $699,000 coolers FW-17 Enhance emergency feedwater flow $17,000 $35,000 $10,000 $17,000 $7,000 $17,000 $19,000 control in the emergency operating procedures FW-18 Replace current pilot operated relief $632,000 $2,700,000 $436,000 $686,000 $282,000 $638,000 $699,000 valves with larger ones such that only one is required for successful feed and bleed FW-19 Create ability to automatically align $10,000 >>$10,000 $7,000 $11,000 $5,000 $11,000 $12,000 emergency feedwater/auxiliary feedwater suction to the other condensate storage tank on low-low level of 2T-41A or 2T-41B HV-03 Develop enhanced procedures for $174,000 >$300,000 $120,000 $189,000 $78,000 $176,000 $193,000 temporary HVAC HV-05 Create ability to switch fan power $104,00 $226,000 $69,000 $111,000 $46,000 $105,000 $116,000 supply to station batteries in a station blackout IA-02 Replace current air compressors with "minimal" >>minimal "minimal" "minimal" "minimal" "minimal" "minimal" more reliable models OT-02 Create a reactor coolant $632,000 $4,600,000 $436,000 $686,000 $282,000 $638,000 $699,000 depressurization system Environmental Report Page E-68 Arkansas Nuclear One - Unit 2

Table E.2-2, Sensitivity Analysis Result (continued)

Estimated Estimated Estimated Estimated Estimated Estimated SAMA Potential Enhancement Benefit Estimated Cost Benefit Benefit Benefit Benefit Benefit ID (baseline) (Sensitivity 1) (Sensitivity 2) (Sensitivity 3) (Sensitivity 4) (Sensitivity 5)

OT-06 Install secondary side guard pipes up $632,000 $1,100,000 $436,000 $686,000 $282,000 $638,000 $699,000 to the main steam isolation valves OT-07 Provide digital large break LOCA $24,000 >>$24,000 $16,000 $26,000 $11,000 $25,000 $27,000 protection Environmental Report Page E-69 Arkansas Nuclear One - Unit 2