ML18158A342

KHNP Environmental Assessment: APR1400 Design Certification (Rin 3150-AJ67; NRC-2015-0225

ML18158A342
Person / Time
Site:	05200046
Issue date:	08/15/2018
From:	Jennivine Rankin Office of New Reactors
To:	Meena Khanna Office of Nuclear Material Safety and Safeguards
Sutton M
References
NRC-2015-0224, RIN 3150-0J67
Download: ML18158A342 (20)

Text

M. Khanna 1 August 15, 2018 MEMORANDUM TO: Meena Khanna, Chief Reactor Rulemaking and Project Management Branch Division of Rulemaking Office of Nuclear Material Safety and Safeguards FROM: Jennivine Rankin, Acting Branch Chief /RA/

Licensing Branch 3 Division of Licensing, Siting and Environmental Analysis Office of New Reactors

SUBJECT:

ENVIRONMENTAL ASSESSEMENT: APR1400 DESIGN CERTIFICATION (RIN 3150-AJ67; NRC-2015-0224)

The Environmental Assessment (EA) referenced in the subject line is ready for transmittal to the Reactor Rulemaking and Project Management Branch, Division of Rulemaking, Office of Nuclear Material Safety and Safeguards. Your office has been given owners rights to the EA (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18158A342). The ADAMS Accession No. for the EA, and all other associated documents are referenced in the enclosure.

All publicly available NRC documents referenced in the EA have been finalized in ADAMS and profiled for public release. The ADAMS Accession numbers for all such documents are provided in the text of the EA.

Enclosure:

Environmental Assessment CONTACT: Mallecia Sutton, NRO/DLSE 301-415-0673

ML18158A342 OFFICE NRO/DSLE:PM NRO:DSLE:LA NRO:DSLE:BC NAME MSutton (JRankin for) SGreen JRankin DATE 8/16/2018 07/03/2018 7/18/2018 OFFICE NRO:DSLE:BC NRO:DSLE:BC NRO:DSLE:DD NAME MMcCoppin MDudek ABradford DATE 8/8/2018 8/8/2018 8/8/2018 OFFICE NRO:DSLE:DD NAME ACampbell DATE 8/15/2018 ENVIRONMENTAL ASSESSMENT BY THE U.S. NUCLEAR REGULATORY COMMISSION RELATING TO THE CERTIFICATION OF THE APR1400 STANDARD PLANT DESIGN DOCKET NO.52-046 Enclosure

Table of Contents 1.0 Identification Of The Proposed Action ----------------------------------------------------------------- 3 2.0 The Need For The Proposed Action-------------------------------------------------------------------- 3 3.0 The Environmental Impact Of The Proposed Action ----------------------------------------------- 3 4.0 Severe Accident Mitigation Design Alternatives ----------------------------------------------------- 4 4.1. Severe Accident Mitigation Design Alternatives ------------------------------------------- 5 4.2. Potential Design Improvements Identified by KHNP ------------------------------------- 7 4.3. NRC Evaluation of Potential Design Improvements -------------------------------------- 9 4.4. Risk Reduction Potential of SAMDAs -------------------------------------------------------- 9 4.4.1. KHNP Evaluation------------------------------------------------------------------------------ 9 4.4.2. NRC Evaluation ------------------------------------------------------------------------------10 4.5. Cost Impacts of Candidate SAMDAs --------------------------------------------------------10 4.5.1. KHNP Evaluation-----------------------------------------------------------------------------10 4.5.2. NRC Evaluation ------------------------------------------------------------------------------11 4.6. Cost-Benefit Comparison-----------------------------------------------------------------------11 4.6.1. KHNP Evaluation-----------------------------------------------------------------------------11 Table 4.6.2-1 Calculated Total Maximum Benefit ------------------------------------------12 4.6.2. NRC Evaluation ------------------------------------------------------------------------------14 4.7. Conclusions on SAMDAs-----------------------------------------------------------------------15 5.0 Finding Of No Significant Impact ----------------------------------------------------------------------- 16

UNITED STATES NUCLEAR REGULATORY COMMISSION ENVIRONMENTAL ASSESSMENT AND FINDING OF NO SIGNIFICANT IMPACT RELATING TO THE CERTIFICATION OF THE APR1400 DESIGN STANDARD PLANT DESIGN DOCKET NO.52-046 The U.S. Nuclear Regulatory Commission (NRC) is proposing a design certification (DC) for the Advanced Power Reactor 1400 (APR1400) design in response to an application submitted on December 23, 2014 by Korea Hydro & Nuclear Power, Inc., hereinafter referred to as KHNP or the applicant. A DC is a rulemaking. The NRC has decided to adopt DC rules as appendices to Part 52 of Title 10 of the Code of Federal Regulations (10 CFR).

The NRC has performed the following environmental assessment (EA) of the environmental impacts of the new rule and has documented its finding of no significant impact in accordance with the requirements of 10 CFR 51.21 and the National Environmental Policy Act of 1969, as amended (NEPA). This EA addresses the severe accident mitigation design alternatives (SAMDAs) that the NRC has considered as part of this EA for the APR1400 design.

This EA does not address the site-specific environmental impacts of constructing and operating any facility that references the APR1400 DC at a particular site; those impacts will be evaluated as part of any application or applications for the siting, construction, or operation of such a facility.

As discussed in Section 5.0 of this EA, the NRC has determined that issuing this DC does not constitute a major Federal action significantly affecting the quality of the human

2 environment. This finding is based on the generic finding made in 10 CFR 51.32(b)(1) that there is no significant environmental impact associated with certification of a standard design under 10 CFR Part 52, Subpart B. The action does not authorize the siting, construction, or operation of a facility using the APR1400 design. Rather, it merely codifies the APR1400 design in a rule that could be referenced in a future combined license application (COLA).

Furthermore, because the certification is a rule rather than a physical action, it does not involve commitment of any resources that have alternative uses. As explained in the statements of consideration for Licenses, Certifications, and Approvals for Nuclear Power Plants; Final Rule, (72 Federal Register (FR) 49352, 49427; August 28, 2007), the 10 CFR 51.32(b)(1) generic finding of no significant impact is legally equivalent to a categorical exclusion. Therefore, the NRC has not prepared an environmental impact statement (EIS) for the action.

Under 10 CFR 51.30(d), an EA for a DC must identify the proposed action and is otherwise limited to consideration of the costs and benefits of SAMDAs and the bases for not incorporating SAMDAs in the DC. As discussed in Section 4.0 of this EA, the NRC also reviewed KHNPs assessment of SAMDAs that generically apply to the APR1400 design. The NRC finds that KHNPs assessment took into consideration a reasonable set of SAMDAs, and that no additional SAMDAs beyond those currently incorporated into the APR1400 design would be cost-beneficial. This finding is applicable whether SAMDAs are considered at the time of the certification of the APR1400 standard design or are considered with respect to licensing a potential future facility referencing the APR1400 DC rule. In 10 CFR Part 52, Appendix F, a plant referencing the APR1400 DC rule should be sited at a location with site characteristics that are encompassed by the postulated site parameters for the DC reference plant site in APR1400-K-X-ER-14001-NP, Revision 2, Applicants Environmental Report - Standard Design Certification, issued August 2018 and supporting documents.

3 ENVIRONMENTAL ASSESSMENT 1.0 Identification Of The Proposed Action The proposed action is to certify the APR1400 design in Appendix F to 10 CFR Part 52.

The new rule allows applicants to reference the certified APR1400 design as part of a COLA under 10 CFR Part 52.

2.0 The Need For The Proposed Action The proposed action is to issue a rule amending 10 CFR Part 52 to certify the APR1400 design. The amendment allows an applicant to reference the certified APR1400 design as part of a COLA under 10 CFR Part 52. Those portions of the APR1400 design included in the scope of the certification rulemaking are not subject to further safety review or approval in a combined license (COL) proceeding. In addition, the DC rule could eliminate the need to consider SAMDAs in connection with any future applications for facilities that reference the certified APR1400 design, in accordance with 10 CFR 51.50(c)(2).

3.0 The Environmental Impact Of The Proposed Action The proposed action constitutes issuance of the DC to 10 CFR Part 52 to certify the APR1400 standard plant design. As stated in 10 CFR 51.32(b)(1), the NRC has determined that there is no significant environmental impact associated with issuance of a DC. The DC merely codifies the NRCs approval of the APR1400 design through its final safety evaluation report on the design issued during rulemaking (refer to NUREG-ML18087A364). Furthermore, because the certification of the design constitutes only a rule rather than a physical action, it would not involve the commitment of any resources that have alternative uses.

As described in Section 4.0 of this EA, the NRC reviewed various alternative design features for preventing and mitigating severe accidents. NEPA requires consideration of alternatives to show that the DC rule is the appropriate course of action. NRC regulations at

4 10 CFR 51.55(a) ensure that the design referenced in rulemaking does not exclude any cost beneficial design changes related to the prevention and mitigation of severe accidents.

Through its own independent analysis, the NRC concludes that KHNP adequately considered an appropriate set of SAMDAs and that none met the cost beneficial criteria.

Although KHNP made no design changes as a result of considering SAMDAs, KHNP had already incorporated certain features in the APR1400 design on the basis of probabilistic risk assessment (PRA) results. Section 4.2 of this EA gives examples of these features. These design features relate to severe accident prevention and mitigation, but were not considered in the SAMDA evaluation because they were already part of the APR1400 design (refer to Sections 19.2.2 and 19.2.3 of the Design Certification Document (DCD), Severe Accident Prevention and Severe Accident Mitigation, respectively).

Finally, the DC rule by itself does not authorize the siting, construction, or operation of a nuclear power plant. An applicant for an early site permit or COL that references the APR1400 design will be required to address the environmental impacts of construction and operation at a specific site. The NRC will then evaluate the environmental impacts and issue an EIS in accordance with 10 CFR Part 51. However, the SAMDA analysis that has been completed as part of this EA can be incorporated by reference into an EIS related to an application for siting, construction, or operation of a nuclear plant that references the APR1400 design.

4.0 Severe Accident Mitigation Design Alternatives The proposed action provides finality in licensing proceedings on an application referencing the APR1400 DC rule and proposing a plant located on a site whose site characteristics fall within the postulated site parameters of the DC reference plant site (i.e., the Surry Power Station site), as described in APR1400-K-X-ER-14001-NP and supporting documents.

5 This section provides a summary of the NRC staff review of KHNPs Standard Design Certification Environmental Report (ER) and the related APR1400 SAMDAs as provided in APR1400-K-X-ER-14001-NP and supporting documents. The specific details of the NRC staffs evaluation, summarized in this EA, are provided in a technical analysis report under Agencywide Documents Access and Management System (ADAMS) Accession No. ML18096A697.

4.1. Severe Accident Mitigation Design Alternatives Consistent with the Commissions objectives of standardization and early resolution of design issues, the SAMDAs are being evaluated as part of the DC for the APR1400 design. In a 1985 policy statement (50 FR 32138; August 8, 1985), the Commission defined the term severe accident as an event that is beyond the substantial coverage of design-basis events, including events where there is substantial damage to the reactor core (whether or not there are serious offsite consequences). Design-basis events are events analyzed in accordance with the NRCs Standard Review Plan (NUREG-0800) and documented in Chapter 15, Safety Analysis, of the DCD.

As part of its DC application, KHNP performed a PRA for the APR1400 design to achieve the following objectives:

• Identify the dominant severe accident sequences that account for most of the core damage frequency (CDF) and associated source terms for the design;

• Modify the design, on the basis of PRA insights, to prevent severe accidents or mitigate their consequences and thereby reduce the risk of such accidents; and

• Provide a qualitative basis for concluding that all reasonable steps have been taken to reduce the chances of severe accidents to occur and to mitigate the consequences.

KHNPs PRA analysis is described in Chapter 19 of the APR1400 DCD, Revision 2.

6 The APR1400 Level 1 and Level 2 PRA models quantified six risk categories, three for operations at-power and three for low-power and shutdown (LPSD) operations, namely:

• At-power internal events;

• At-power internal flooding events;

• At-power internal fire events;

• LPSD internal events;

• LPSD internal flooding events; and

• LPSD internal fire events.

The risks from other external events, such as high winds, seismic events, external flooding, external fires, etc., were determined by the PRA models to be negligible and were not further analyzed under the SAMDA assessment.

In addition to these safety considerations, applicants for reactor DC or COLs must also consider alternative design features for severe accidents as part of the NRCs environmental review. These requirements can be summarized as follows:

• 10 CFR 52.79(a)(46) requires a COL applicant to describe the plant-specific PRA and its results, with the aim of identifying potential improvements in the reliability of the core and containment heat removal systems that are significant and practical and, which do not impact excessively on the plant.

• 10 CFR 51.30(d) requires consideration of SAMDAs in an EA for a DC, while 10 CFR 51.50(c) sets forth the general requirements for an ER accompanying a COLA, including the requirement to evaluate SAMDAs.

Although these requirements are not directly related, they share common purposes, which are to consider alternatives to the proposed design, to evaluate whether potential alternative improvements in the plant design might significantly enhance safety performance during severe accidents, and to prevent reasonable alternatives from being foreclosed.

7 The NRC has determined that generic evaluation of SAMDAs for the APR1400 standard design is both practical and warranted for two reasons. First, the design and construction of all plants referencing the certified APR1400 design will be governed by the rule certifying a single design. Second, the site parameters in APR1400-K-X-ER-14001-NP and supporting documents establish the consequences for a reasonable set of SAMDAs for the APR1400 design. The low residual risk of the APR1400 design and the limited potential for further risk reduction provides high confidence that additional cost-beneficial SAMDAs would not be found for sites with characteristics that fit within the site parameter envelope. If an actual characteristic for a particular site does not fall within the postulated site parameters, then SAMDAs that could be affected by the value of the site characteristic must be re-evaluated in the site-specific ER and the EIS prepared in connection with the application. If the actual characteristics of a proposed site fall within the postulated site parameters, then the SAMDA analysis can be incorporated by reference in the site-specific EIS and SAMDAs need not be re-evaluated in the EIS.

4.2. Potential Design Improvements Identified by KHNP In APR1400-K-X-ER-14001-NP and supporting documents, the applicant identified 153 candidate design alternatives, or design improvements, based on a review of the standard list of design alternatives provided in Table 14 of NEI 05-01A, Severe Accident Mitigation Alternatives (SAMA) Analysis, and several license renewal ERs. KHNP eliminated certain candidate design alternatives from further consideration on the following bases:

• They were already implemented in the APR1400 design;

• They were not applicable to the APR1400 design or to the APR1400 DC;

• They had excessive implementation costs; or

• They were of very low benefit.

There were 30 candidate design alternatives that the APR1400 design already incorporated such as the following:

8

• Installing a gas turbine generator;

• Installing an independent active or passive high pressure injection system;

• Adding a diverse low pressure injection system;

• Improving emergency core cooling system suction strainers;

• Adding the ability to manually align emergency core cooling system recirculation;

• Adding the ability to automatically align emergency core cooling system to recirculation mode upon refueling water storage tank depletion;

• Providing an in-containment reactor water storage tank;

• Creating a reactor coolant depressurization system; and

• Installing an independent reactor coolant pump seal injection system, without dedicated diesel.

The applicants screening process eliminated 30 potential design alternatives that were identified as being unfeasible due to excessive implementation costs or that provided negligible benefit. Another 54 SAMDA candidates were identified as not applicable to the DC stage of plant development (such as procedural processes, training, or a design features not applicable at the DC stage). One potential design alternative was determined to be of very low benefit.

The applicant retained the remaining 38 SAMDAs for further assessment in the cost-benefit analysis.

KHNP also applied insights from the APR1400 PRA by applying relevant guidance from Section 5.1, Probabilistic Safety Assessment (PSA) Importance, in NEI 05-01A. First, KHNP identified APR1400-specific dominant risk contributors, derived from the PRA, for further consideration for events. This subset of risk contributors was derived from an importance analysis of core damage cutsets using a Fussell-Vessely (FV) importance criterion of greater than 0.5 percent contribution to the total risk (i.e., the total CDF). By applying this criterion, KHNP identified a number of basic events derived from the information in DCD Section 19.1.

9 This process identified basic events in Section 7 of the ER that are associated with the six risk categories (see Tables 6a through 6f). Secondly, KHNP applied insights from the APR1400 PRAs top 100 cutsets by identifying any not included as part of the FV importance analysis review. KHNP identified these additional at-power and LPSD basic events as provided in Tables 7a through 7f of the ER for further consideration based on the information in DCD Section 19.1.

4.3. NRC Evaluation of Potential Design Improvements The NRC staff found that the set of SAMDAs and basic events evaluated by KHNP addresses the major contributor to core damage. KHNP used a systematic and comprehensive process for identifying potential plant improvements for the APR1400 design, and the set of potential plant improvements identified by KHNP is reasonably comprehensive and, therefore, is acceptable for further evaluation. This included reviewing insights from the plant-specific PRA study as well as assessing severe accident mitigation alternatives (SAMAs) based on accepted industry guidance.

The NRC has concluded that the applicants assessment of the potential SAMDAs and their impacts on the APR1400 design is acceptable. The NRCs review did not reveal any additional design alternatives that the applicant should have considered.

4.4. Risk Reduction Potential of SAMDAs 4.4.1. KHNP Evaluation KHNP evaluated the potential SAMDAs not screened out to assess their potential benefits by using bounding techniques to estimate the possible risk reduction. This is accomplished by associating the basic events identified with a FV importance of greater than 0.5 percent, and from the top 100 cutsets to a particular SAMDA. This linkage to a SAMDA is provided for each basic event in APR1400-K-X-ER-14001-NP, Section 7.1 through Section 7.19. The basic event that a potential SAMDA is associated with is also provided in the Qualitative Screening column of Table 5 in APR1400-K-X-ER-14001-NP.

10 Because there are likely several basic events that are considered under a specific SAMDA, KHNP applied a factor of risk reduction based on the sum of FV importance values for each basic event. KHNP determined the sum of FV values for each basic event under the six risk categories for a total risk reduction percentage associated with a particular risk category (i.e., at-power internal events, internal flooding, and internal fire; LPSD internal events, internal flooding, and internal fire). In several basic event cases, KHNP found there were no FV importance values so the sum for a risk category would be zero. Section 4.4.2 discusses this assessment further.

4.4.2. NRC Evaluation The NRC staff reviewed KHNPs bases for calculating the risk reduction for the various plant improvements and concludes that the rationale and assumptions for estimating risk reduction are reasonable. Specifically, the sum of FV importance values for risk reductions is acceptable due to its conservatism (i.e., the estimated risk reduction is higher than what would actually be realized). Accordingly, the NRC staff based its estimates of averted risk for the potential SAMDAs on the resulting APR1400 risk reduction estimates.

4.5. Cost Impacts of Candidate SAMDAs 4.5.1. KHNP Evaluation In performing the cost benefit analysis of the SAMDAs considered, the cost of enhancement (COE) implementation associated with potential events are estimated from available information related to similar events and components of other nuclear power plant designs. The COE cost values of the APR1400 SAMDAs are derived from two sources. The first source is the compilation of information from the SAMA1 analyses performed for the license renewal applications of the presently operating nuclear power plants as documented in the licensees renewal (LR) ERs and in the final supplemental EISs under NUREG-1437. The 1 SAMDAs are a subset of SAMAs. SAMAs have as attributes for the mitigation of severe accidents of design alternatives (i.e., SAMDAs), procedural modifications, and training activities.

11 second source is an assessment by the applicant as presented in APR1400-K-X-ER-14001-NP.

The publicly available LR SAMA costs are full-cost values while the associated SAMDA cost applied by KHNP were conservatively set to half of the license renewal values based on an assumption that half of the cost would be from engineering and procedure updates. However, it is important to note for LR SAMA evaluations, the full SAMA costs were applied in their cost-benefit analyses.

4.5.2. NRC Evaluation On the basis of the analyses performed by KHNP, the NRC staff has concluded that the applicants estimates of potential costs for the APR1400 SAMDAs are acceptable because the sources for the information and the cost estimates are both reasonable. The NRC staff applied this information in the cost benefit analysis first using half of the SAMDA COE implementation value, as did KHNP for the APR1400 evaluation presented in APR1400-K-X-ER-14001-NP. If SAMDAs were not further screened out based on the conservative assumptions, then the NRC staff applied the full COE implementation value. This approach facilitates the cost benefit comparisons founded on a graded approach when assessing the averted costs using 7 percent then 3 percent discount rates. This approach is consistent with the guidance in Section 7.2 of NEI 05-01A.

4.6. Cost-Benefit Comparison 4.6.1. KHNP Evaluation The methodology used by KHNP was based primarily on the NRCs guidance for performing cost-benefit analysis outlined in NUREG/BR-0184, Regulatory Analysis Technical Evaluation Handbook. The guidance involves determining the net present value (NPV) for each SAMDA according to the following formula:

NPV = (APE + AOC + AOE + AOSC) - COE Where:

NPV = Net present value of current risk ($);

12 APE = Present value of averted public exposure ($);

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

AOE = Present value of averted occupational exposure ($);

AOSC = Present value of averted onsite costs ($); and COE = Cost of any enhancement implemented to reduce risk ($).

For the representation of the maximum benefit that could be provided, the maximum benefit is calculated to be the sum of the four averted cost categories. It is represented as:

Maximum Benefit = APE + AOC + AOE + AOSC If the net value of a SAMDA is negative, the cost of implementing the SAMDA is larger than the benefit associated with the SAMDA and it is not cost beneficial. Table 4.6.2-1 summarizes the applicants and the NRCs estimates of each of the associated cost elements.

Table 4.6.2-1 Calculated Total Maximum Benefit KHNP NRC Staff Risk Category 7% 3% 7% 3%

APE $49,877 $98,622 $49,872 $98,612 AOC $63,933 $126,417 $63,941 $126,429 AOE $3,817 $8,787 $3,818 $8,786 AOSCCD $116,457 $276,642 $191,035 $453,773 AOSCRP $675,084 $1,134,638 $706,726 $1,879,727 Total Maximum

$909,168 $1,645,106 $1,015,393 $2,567,327 Benefit It is important to note that the monetary present value estimate for each risk attribute does not represent the expected reduction in risk resulting from a single accident. Rather, it is the present value of a stream of potential losses extending over the projected lifetime (in this case, 60 years) of the facility. Therefore, it reflects the expected annual loss resulting from a single accident, the possibility that such an accident could occur at any time over the licensed life, and the effect of discounting these potential future losses to present value.

The NRC issued Revision 4 of NUREG/BR-0058, Regulatory Analysis Guidelines of the U.S. Nuclear Regulatory Commission, in August 2004 to reflect the agency's policy on discount

13 rates. NUREG/BR-0058, Revision 4, states that two sets of estimates should be developed one at 3 percent and one at 7 percent. The applicant provided estimates using both discount rates.

KHNP calculated the maximum benefit for at-power internal events, internal flooding events, and internal fire events; along with LPSD internal events, internal flooding events, and internal fire events for the baseline 7 percent and the sensitivity 3 percent discount rates. The results of the KHNP evaluation is provided in Table 4.6.2-1.

If the implementation costs for a SAMDA candidate exceeds the calculated maximum benefit resulting in a negative NPV, the SAMDA is not cost-beneficial. If the SAMDA benefit exceedes the estimated cost resulting in a positive NPV, the SAMDA is potentially cost-beneficial. As previously discussed, 38 SAMDAs were carried to the next screening phase. In addition to these remaining SAMDAs, each basic event with FV importance of greater than 0.5 percent or part of the top 100 cutsets, if not already included as a basic event, were reviewed to identify any potential SAMDAs. KHNP then related each of the 38 SAMDAs back to one or more of the basic events and assessed the NPV for each basic event with the following steps:

1. Assessed the maximum benefit for each basic event applying conservative assumptions for risk reductions to the AOE and AOSC cost categories;

2. Conservatively assessed the COE based on half of the SAMDA values obtained from source documents; and

3. Determined the NPV.

For each of the basic events/SAMDAs applying the 7 percent and 3 percent discount rates, KHNP evaluated the NPV and reached a conclusion of whether the enhancements were cost beneficial. KHNPs SAMDA analysis determined that there were no potentially cost-beneficial enhancements for the 7 percent discount rate analysis. KHNPs states that while their sensitivity analysis for the 3 percent discount rate showed a higher maximum benefit over

14 the 7 percent discount rate, they concluded that no design changes would provide a positive cost-benefit for either discount rate if included in the APR1400 design.

4.6.2. NRC Evaluation As shown in Table 4.6.2-1, the NRC staffs confirmatory analysis for the 7 percent and 3 percent discount rates were in general agreement with the applicant for the offsite public exposure (i.e., APE), offsite property damage cost (i.e., AOC), and onsite occupational dose (i.e., AOE) averted costs. The NRC staff evaluation resulted in higher values than the applicants evaluation for the onsite cleanup and decontamination (i.e., AOSCCD) averted costs with a similar higher result for the replacement power (i.e., AOSCRP) averted costs.

In the AOSCCD evaluation, the NRC staff adjusted the base averted cost per event provided by NUREG/BR-0184, which was applied by KHNP, to current dollars resulting in a higher value for the NRC staffs evaluation. The small difference between the NRC staffs and the applicants AOSCRP averted costs for the 7 percent discount rate evaluation is principally due to applying different inflation factors to adjust the base replacement cost to current dollars.

For the 3 percent discount rate analysis of the replacement power, KHNP applied a linear interpolation to the NPV for discount rates below 5 percent as described near the end of Section 5.7.6.2 of NUREG/BR-0184 (see page 5.45 of NUREG/BR-0184). Based on staff experience in prior regulatory rulemaking analysis, the NRC staff applied the same replacement cost formula for both the 7 percent and 3 percent discount rates (see the formula in Section 5.7.6.2 of NUREG/BR-0184 on page 5.44). This is viewed by the NRC staff as being conservative as demonstrated by the larger replacement power averted cost in the NRC staff evaluation over the applicants evaluation.

The NRC staff review noted that the applicant used two assumed conservatisms in their cost-benefit analysis. The first case of conservatism involved the total averted costs in each analysis where the applicant did not apply the percent risk reductions for the contribution to total CDF to the population dose (i.e., APE) and offsite property damage (i.e., AOC) costs. The

15 value of APE and AOC were based on MELCOR Accident Consequence Code System calculations and, thus, are directly tied to the size of a release. As shown by the NRC staffs 3 percent discount rate analysis compared to the KHNP 3 percent discount rate analysis, applying this reduction to only the onsite exposure (i.e., AOE) and onsite economic costs (i.e., AOSC) results in a conservative result. Namely, it will result in a total maximum benefit that is larger than if the percentage risk reduction is applied to all cost categories. The second conservative assumption involved the use of the determined COE values, as discussed in Section 4.5.1. As assessed by the NRC staff, when the applicant applies only half of the estimated COE value, the final determination of the cost-benefit analysis could more likely provide a positive NPV.

Even with the above discussed differences in the averted cost values, the NRC staffs confirmatory analysis also reached the same conclusion as KHNP that there were no cost beneficial design alternatives when applying a 7 percent discount rate. This result is the same whether applicants conservative assumptions were, or were not, applied in the 7 percent discount rate analysis. Based on the NRC staffs review of the methodology and associated analysis, KHNPs assessment adequately addressed the cost-benefit analysis for the 7 percent discount rate.

For the 3 percent discount rate analysis, the NRC staff performed a confirmatory calculation to assess the cost-benefits applying the NRC staff results provided in Table 4.6.2-1 without applying KHNPs conservative assumptions. Specifically, the NRC staff also applied the risk reduction percentages to the APE and AOC values since they are also dependent on the released plume, and applied the full COE values. As a result, the NRC staff determined there were no cost beneficial design alternatives when applying a 3 percent discount rate.

4.7. Conclusions on SAMDAs The NRC staff reviewed KHNPs SAMDA analysis and concludes that the methods used and the implementation of the methods are appropriate. On the basis of the applicants treatment of SAMDA benefits and costs, the NRC staff finds that the evaluation performed by

16 KHNP is reasonable and sufficient. Based on its own independent evaluation, the NRC staff reached the same conclusion as KHNP that none of the possible candidate design alternatives are potentially cost beneficial for the APR1400 design. This independent evaluation was based on reasonable treatment of costs, benefits, and sensitivities. Based on the NRC review of KHNPs evaluation, including KHNPs response to requests for additional information, the NRC staff concludes that KHNP has adequately identified areas where risk potentially could be reduced in a cost-beneficial manner and adequately assessed whether the implementation of the identified potential SAMDAs or candidate design alternatives would be cost-beneficial for the given site parameters.

Because of the magnitude of the negative NPV values, a SAMA based on operational procedures or training for an APR1400 reactor would have to cause a significant effect on the total CDF and/or have a low implementation cost to become cost beneficial. Based on its evaluation, the NRC staff concludes that it is unlikely that any of the SAMAs based on procedures or training would reduce the risk to be cost beneficial for the given site parameters.

5.0 Finding Of No Significant Impact On the basis of the EA, the NRC concludes that the proposed action will not have a significant effect on the quality of the human environment. Accordingly, the NRC is not required to prepare an EIS for the proposed action.

For further details with respect to the proposed action, see the DC rule and the documents referenced in the statement of considerations for the final rule. Documents may be examined, and/or copied for a fee, at the NRCs Public Document Room (PDR), located at One White Flint North, 11555 Rockville Pike (first floor), Rockville, Maryland, 20852. Publicly available records will be accessible electronically from the ADAMS Public Electronic Reading Room on the NRC Web site at http://www.nrc.gov/reading-rm/adams.html. Persons who do not have access to ADAMS or who encounter problems in accessing the documents in ADAMS

17 should contact the NRC PDR reference staff at 1-800-397-4209 or 301-415-4737 or send an e-mail to pdr@nrc.gov.