ML17261B285
| ML17261B285 | |
| Person / Time | |
|---|---|
| Site: | 05200046 |
| Issue date: | 09/15/2017 |
| From: | Korea Hydro & Nuclear Power Co, Ltd |
| To: | Office of New Reactors |
| Shared Package | |
| ML17261B283 | List: |
| References | |
| MKD/NW-17-0293L | |
| Download: ML17261B285 (5) | |
Text
EIS ACC/SAMDA-4_Rev.1 - 1 / 3 KEPCO/KHNP REVISED RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION APR1400 Design Certification Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD Docket No.52-046 RAI No.: ER 1-8429 SRP Section: Environmental Report Application Section: APR1400 Environmental Report Date of RAI Issue: 03/22/2016 Question No. EIS ACC/SAMDA-4 10 CFR 51.55(a) requires each applicant for a standard design certification under subpart B of 10 CFR Part 52 (i.e., 10 CFR 52.47(b)(2)) to submit with its application a separate document entitled, "Applicant's Environmental ReportStandard Design Certification." The environmental report must address the costs and benefits of severe accident mitigation design alternatives, and the bases for not incorporating severe accident mitigation design alternatives in the design to be certified.
The environmental standard review plan (ESRP) Section 7.3, Severe Accident Mitigation Alternatives, directs the staff to evaluate and independently confirm an applicants severe accident mitigation design alternatives (SAMDAs) analysis presented in an Environmental Report (ER) (i.e., the APR1400 ER, Applicants Environmental Report - Standard Design Certification, found under ML15006A038 and the technical report, Severe Accident Mitigation Design Alternatives (SAMDAs) for the APR1400, proprietary under ML15012A105 and nonproprietary under ML15009A246) that applies design and site information along with a cost benefit analysis based on the guidance provided in NUREG/BR-0184. The scope includes the identification and evaluation of design alternatives and procedural modifications that reduce the radiological risk from a severe accident by preventing substantial core damage (i.e., preventing a severe accident) or by limiting releases from containment in the event that substantial core damage occurs (i.e., mitigating the impacts of a severe accident). The purpose of the review is to ensure that plant design changes with the potential for improved severe accident safety performance are identified and evaluated.
The staff requires the following additional information in order to complete its review of the environmental impacts of severe accidents and to ensure appropriate documentation of the applicants assessment in the APR1400 Environmental Report.
Provide additional documentation in the ER or supporting technical reports to explain the purpose, need and development of Tables 5a through 5f and Tables 6a through 6f of APR1400-E-P-NR-14006-P. The discussion of these tables in Section 6 and 7 of APR1400-E-P-NR-
EIS ACC/SAMDA-4_Rev.1 - 2 / 3 KEPCO/KHNP 14006-P is very brief (see pages 17 and 19) and does not provide a rationale as to how the information was developed, why each important basic event is being presented in the tables, and if there is any relationship to the Subsections 7.1 through 7.22 of APR1400-E-P-NR-14006-P.
The NRC staff request that any revisions to the ER or supporting technical reports be provided as a markup as part of the response to this RAI.
The response to this RAI also may need to be reflected in the DCDs FSAR Chapter 19.
This RAI is related to the Environmental Audit Information Needs ER-TI-13 (ML15198A023).
Response - (Rev. 1)
The ASME PRA Standard (ASME/ANS RA-Sb-2013) defines a significant basic event as a basic event that contributes significantly to the computed risks for a specific hazard group.
This definition includes any basic event that has an FV importance greater than 0.005 or a RAW importance greater than 2. For the SAMDA analysis (APR1400-E-P-NR-14006-P, APR1400-E-P-NR-14006-NP, and Environmental Report), Tables 5a through 5f include basic events with FV importance greater than 0.005 (0.5%), as the purpose of the SAMDA analysis is to consider ways to reduce risk. The RAW importance parameter does not provide indication of potential risk reduction and is not germane to a SAMDA analysis for risk reduction. Therefore, the RAW importance measure is not used.
Tables 6a through 6f include basic events from the top 100 cutsets that do not have a FV importance greater than 0.005 (0.5%). These basic events were reviewed because they could be considered important based on the order they appear in the cutsets. NEI-05-01, Severe Accident Mitigation Alternatives (SAMA) Analysis Guidance Document, allows the open interpretation for the definition of dominant cutsets, provided justification is give. As is documented in the APR1400 DCD Table 19.1-19, the top 100 internal events cutsets contribute approximately 39 percent of the total CDF and the number of cutsets that contribute to 95 percent of the CDF is over 200,000. Review of additional basic events that do not have a FV importance greater than 0.005 (0.5%) and are outside the top 100 cutsets would have little influence on CDF and are therefore not likely contributors for identification of cost benefit enhancements.
Additionally, RAI ACC/SAMDA-7 has addressed updating Tables 5a through 5f to include specific subsections of Section 7 (SAMDA Benefit Evaluation) for the specific component basic event analyzed.
Impact on DCD There is no impact on the DCD.
Impact on PRA There is no impact on the PRA.
EIS ACC/SAMDA-4_Rev.1 - 3 / 3 KEPCO/KHNP Impact on Technical Specifications There is no impact on the Technical Specifications.
Impact on Technical/Topical/Environmental Reports Section 5 of the SAMDA documents (Enclosure #103 - APR1400-E-P-NR-14006-P, Rev. 0 and Enclosure #104 - APR1400-E-P-NR-14006-NP, Rev. 0) will be revised to include the information added in Attachment 1.
Section 5 of the APR1400 Applicants Environmental Report (ML15006A038 / APR1400-K-X-ER-14001-NP, Rev. 0) will be revised to include the information added in Attachment 2.
RAI ER 1-8429 - Question EIS ACC/SAMDA-4_Rev.1 Attachment 1 (1/1)
SAMDAs APR1400-E-P-NR-14006-NP, Rev. 0
- 5. IDENTIFICATION OF SAMDAS The list of SAMDA items evaluated for the APR1400 design is given in Table 4.
The first source used to identify SAMDA items is NEI-05-01. Generic industry SAMDAs that are to be considered are the 153 items that are identified in Table 14 of NEI 05-01 (Reference 1).
The second source used to identify SAMDA items is APR1400 design-specific SAMDA items that be decided through expert panel for APR1400 SAMDA. The 29 items for APR1400 design-specific SAMDA are described in Table 4.
The third source used to identify SAMDA items is the result of PRA for APR1400. Evaluation of APR1400-specific items related to the PRA results began with an importance analysis of the core damage cutsets generated in Reference 5. Each basic event with a Fussell-Vesely importance of greater than 0.5 percent was reviewed to identify any potential SAMDAs. These included 118 basic events for at-power internal events, 64 for at-power internal flooding events, 92 for at-power fire events, 73 for LPSD internal events, 53 for LPSD internal flooding events, and 141 for LPSD fire events. Basic events, such as complementary events or constants, have no physical meaning are identified and can be excluded as having no impact on the SAMDA analysis. A listing of the basic events, their importance, and their disposition with respect to SAMDA items is given in Tables 5a through 5f.
In addition to the basic event importance review, the top 100 cutsets for each analysis were reviewed to identify any basic events that were not included as part of the importance analysis review. Basic events identified in the top 100 cutsets that are not included as part of the importance analysis review are shown in Tables 6a through 6f.
The ASME PRA Standard (ASME/ANS RA-Sb-2013) defines a significant basic event as a basic event that contributes significantly to the computed risks for a specific hazard group. but could be considered This definition includes any basic event that has a FV importance important based on their greater than 0.005 (0.5%) or a RAW importance greater than 2. order in the cutsets The purpose of the SAMDA analysis is to consider ways to reduce risk. The RAW importance parameter does not provide indication of potential risk reduction and is not germane to a SAMDA analysis for risk reduction. Therefore, the RAW importance measure is not used.
KEPCO & KHNP 17
RAI ER 1-8429 - Question EIS ACC/SAMDA-4_Rev.1 Attachment 2 (1/1)
APR1400 Applicants Environmental Report - Standard Design Certification
- 5. IDENTIFICATION OF SAMDAS The list of SAMDA items evaluated for the APR1400 design is given in Table 4.
The first source used to identify SAMDA items is NEI 05-01 (Reference 1). Generic industry SAMDAs that were considered are the 153 items listed in Table 14 of NEI 05-01.
The second source used to identify SAMDA items is APR1400 design-specific SAMDA items that be decided through expert panel for APR1400 SAMDA. The 29 items for APR1400 design-specific SAMDA are described in Table 4.
The third source used to identify SAMDA items is the result of PRA for APR1400. The evaluation of APR1400-specific items related to PRA results began with an importance analysis of the core damage cutsets. The following events were reviewed to identify potential SAMDAs: basic events with a Fussell-Vesely (FV) importance of greater than 0.5 percent, a total of 118 basic events for at-power internal events, 64 for at-power internal flooding events, 92 for at-power internal fire events, 73 for LPSD internal events, 53 for LPSD internal flooding events, and 141 for LPSD internal fire events. Basic events without physical meaning, such as complement events and constants, were identified and excluded because they would have no impact on the SAMDA analysis. A list of the basic events, their importance, and their disposition with respect to SAMDA items is given in Tables 5a through 5f of the APR1400 SAMDA Technical Report (Reference 4).
In addition to the basic event importance review, the top 100 cutsets for each analysis were reviewed to identify any basic events that were not included in the importance analysis review. Basic events identified in the top 100 cutsets that were not included in the importance analysis review are provided in Tables 6a through 6f of the APR1400 SAMDA Technical Report (Reference 4).
The ASME PRA Standard (ASME/ANS RA-Sb-2013) defines a but could be considered significant basic event as a basic event that contributes important based on their significantly to the computed risks for a specific hazard group.
order in the cutsets This definition includes any basic event that has a FV importance greater than 0.005 (0.5%) or a RAW importance greater than 2.
The purpose of the SAMDA analysis is to consider ways to reduce risk. The RAW importance parameter does not provide indication of potential risk reduction and is not germane to a SAMDA analysis for risk reduction. Therefore, the RAW importance measure is not used.
5-1 Rev. 0