ML14259A452
| ML14259A452 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 09/16/2014 |
| From: | Jeffrey Whited Plant Licensing Branch 1 |
| To: | |
| Whited J | |
| References | |
| TAC MF3985, TAC MF3986 | |
| Download: ML14259A452 (5) | |
Text
DRAFT REQUEST FOR ADDITIONAL INFORMATION OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR ADDITIONAL INFORMATION RELATED TO A LICENSE AMENDMENT REQUEST TO EXTEND CONTAINMENT LEAKAGE TEST FREQUENCY BEAVER VALLEY POWER STATION - UNITS 1 AND 2 DOCKET NO. 50-344 AND 50-412 By letter dated April 16, 2014,1 FirstEnergy Nuclear Operating Company (the licensee) submitted a license amendment request for Beaver Valley Power Station (BVPS) Units 1 and
- 2. The proposed amendment would modify BVPS Technical Specification 5.5.12, Containment Leakage Rate Testing Program, Item a, be deleting reference to the BVPS-1 exemption letter dated December 5, 1984,2 and requiring compliance with Nuclear Energy Institute (NEI) topical report NEI 94-01, Revision 3-A,3 Industry Guideline for Implementing Performance-Based Option of [Title 10 to the Code of Federal Regulations] 10 CFR Part 50 Appendix J, instead of Regulatory Guide 1.163,4 Performance Based Containment Leak Test Program, including listed exceptions. This change will allow BVPS 1 and 2 to extend the Type A reactor containment test, required by 10 CFR Part 50 Appendix J, test interval from one test in 10 years up to one test in 15 years and extension of the Type C test interval up to 75 months. To complete its review, the Nuclear Regulatory Commission (NRC) staff in the Probabilistic Risk Assessment Licensing Branch (APLA) and the Containment and Ventilation Branch (SCVB) request a response to the questions below.
APLA RAI 1 According to Regulatory Issue Summary 2007-06,5 Regulatory Guide 1.200 Implementation, the NRC staff expects that licensees fully address all scope elements with Revision 2 of Regulatory Guide (RG) 1.200,6 An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activites by the end of its implementation period (i.e., one year after the issuance of Revision 2 of RG 1.200). Revision 2 of RG 1.200 endorses, with exceptions and clarifications, the combined American Society of Mechanical Engineers (ASME)/American Nuclear Society (ANS) PRA standard (ASME/ANS RA-Sa-2009).
The methodology provided in Electric Power Research Institute (EPRI) Technical Report (TR) 1009325, Revision 2,7 Risk Impact Assessment of Extended 1
Agencywide Documents Access and Management System (ADAMS) Accession No. ML14111A291.
2 ADAMS Accession No. ML003766713.
3 ADAMS Accession No. ML12221A202.
4 ADAMS Accession No. ML003740058.
5 ADAMS Accession No. ML070650428.
6 ADAMS Accession No. ML090410014.
7 ADAMS Accession No. ML072970208.
DRAFT
Integrated Leak Rate Testing Intervals, to confirm the risk impact of the Integrated Leak Rate Testing (ILRT) extension on a plant-specific basis relies on use of internal events and the available plant-specific risk analyses for external events. EPRI Report No. 1009325, Revision 2, does not address plant-specific probabilistic risk assessment (PRA) quality. In the safety evaluation report (SER) for the EPRI TR-1009325, Revision 2, dated June 25, 2008,8 the NRC staff, stated, in part, that:
[l]icensee requests for a permanent extension of the ILRT surveillance interval to 15 years pursuant to NEI TR 94-01, Revision 2, and EPRI Report No. 1009325, Revision 2, will be treated by NRC staff as risk-informed license amendment requests. Consistent with information provided to industry in Regulatory Issue Summary 2007-06, Regulatory Guide 1.200 Implementation, the NRC staff will expect the licensees supporting Level 1/[large early release frequency] LERF PRA to address the technical adequacy requirements of RG 1.200, Revision 1 Any identified deficiencies in addressing this standard shall be assessed further in order to determine any impacts on any proposed decreases to surveillance frequencies. If further revisions to RG 1.200 are issued which endorse additional standards, the NRC staff will evaluate any application referencing NEI TR 94-01, Revision 2, and EPRI Report No. 1009325, Revision 2, to examine if it meets the PRA quality guidance per the RG 1.200 implementation schedule identified by the NRC staff.
Given that the implementation date of RG 1.200, Revision 2, was April 2010 and the license amendment request (LAR) was submitted in April 2014, identify any gaps between the BVPS PRA models used in this application and RG 1.200, Revision 2 requirements, that are relevant to this submittal and address the technical adequacy requirements of RG 1.200, Revision 2, or explain why addressing the requirements would have no impact on this application.
APLA RAI 2 In the SER for the EPRI TR-1009325, Revision 2, the NRC staff stated, in part, that for licensee requests for a permanent extension of the ILRT surveillance interval to 15 years [c]apability category I of ASME RA-Sa-2003 shall be applied as the standard, since approximate values of CDF and LERF and their distribution among release categories are sufficient for use in the EPRI methodology.
In Table 2 of Attachments 5 and 6 to the LAR, the licensee provided a brief summary of the BVPS final resolutions to all of the 2007 BVPS PRA Self-Assessment, 2007 BVPS HRA Focused Peer Review, and the 2011 BVPS Internal Flood PRA Focused Peer Review Facts and Observations (F&Os), which resulted in a change to the PRA model. The licensee further stated, in part, that:
[a]ll other F&Os from these assessment/reviews were considered to be documentation issues, and did not impact the PRA models.
Provide a list of all findings from the past peer-reviews and self-assessments (including the assessment in response to Question 1) relevant to this submittal for which the PRA did not meet the ASME/ANS PRA Standard capability 8
ADAMS Accession No. ML081140105.
category 1 supporting requirements. Summarize why not meeting each capability category 1 requirement will have no impact on this application.
APLA RAI 3 EPRI TR-1009325, Revision 2-A states that [w]here possible, the analysis should include a quantitative assessment of the contribution of external events (for example, fire and seismic) in the risk impact assessment for extended ILRT intervals. For example, where a licensee possesses a quantitative fire analysis and that analysis is of sufficient quality and detail to assess the impact, the methods used to obtain the impact from internal events should be applied for the external event. For the ILRT extension request, the NRC staff can use RG 1.200, Revision 2, to determine the quality and detail of fire analyses. RG 1.200, Revision 2, endorses a peer review using the ASME/ANS-Sa-2009 Standard with comments and clarifications.
(a) Given that peer-reviewed Fire PRA (FPRA) models of BVPS-1 and BVPS-2 have been used in the LAR to adopt National Fire Protection Association Standard 805, Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants, 2001 Edition, on December 23, 2013,9 discuss the reasons that these peer-reviewed FPRA models were not used to estimate the contribution of fire to LERF, core damage frequency (CDF), conditional containment failure probability (CCFP) and increase in the total population dose for this application.
(b) Discuss whether using the peer-reviewed FPRA model would significantly change the total estimated LERF, CDF, CCFP and increase in the total population dose.
APLA RAI 4 In Section 3.2.2 of the SER for the EPRI TR-1009325, Revision 2, the NRC staff stated, in part, that:
EPRI Report No. 1009325, Revision 2, also includes an assessment of the impact of the proposed change on the radiological dose to the population within a 50-mile radius of the plant. The population dose metric reflects the combined impact of the proposed change on all containment release modes/categories (including minimal, small, and large releases in both the early and late time periods), in lieu of focusing only on large early releases. This metric provides perspective on the overall impact of the proposed change on offsite consequences and ensures that these impacts will be small.
In Section 7 of Attachment 4 to the LAR, the licensee stated:
The change in dose risk increases to 1.21E+00 person-rem/yr when including the impact from a loss of containment overpressure (see Table 6-5). However, only 1.30E-02 person-rem/yr is attributed to the increase in the Class 3b population dose, while 1.19 person-rem/yr (2.43E+01 minus 2.31E+01) is due to the increase in the Class 7 non-LERF frequency.
(a) Given that the reported increase in population dose rate of 1.21 person-rem/yr is larger than an acceptably small increase in population dose defined 9
ADAMS Accession No. ML14002A086.
in Section 3.2.4.6 of the SER for the EPRI TR-1009325, Revision 2 (an increase in population dose of less than or equal to either 1.0 person-rem per year or 1 percent of the total population dose, whichever is less restrictive),
explain why the requested ILRT extension should be accepted, even though the staff generally does not accept applications that exceed the guidelines.
(b) Provide the largest ILRT extension period at which the increase in population dose rate is less than the acceptance guideline of 1.0 person-rem/yr.
(c) As the acceptance guideline for the increase in population dose rate provides perspective on the overall impact of the proposed change on offsite consequences (including consequences from small releases in late time periods), describe the reasons that the BVPS-2 increase in population dose rate of 1.19 person-rem/yr from EPRI Accident Class 7 non-LERF (Severe accident phenomena-induced failures, non-LERF), by itself, is larger than the acceptance guideline.
APLA RAI 5 In Section 5.1 of Attachments 3 and 4 to the LAR, the licensee stated, in part, that:
a containment isolation analysis was performed to estimate the frequency of failure to isolate lines that could cause a significant risk of radioactive release. The results of this analysis screened-out all containment penetrations > 2-inch diameter. Furthermore, the Beaver Valley Power Station containments are operated at slightly sub-atmospheric pressures (BVPS Technical Specification LCO 3.6.4 states that containment pressure shall be 12.8 psia and 14.2 psia), thus the baseline PRA models do not consider a large pre-existing loss of containment isolation to be credible.
Therefore, the frequency per year for these Class 2 sequences is assumed to be zero.
Section 4.3 of EPRI TR-1009325, Revision 2, provides guidance for calculating frequency per year for these sequences as follows:
F Class 2 = PROB large CI
- CDF Total Where:
PROB large CI = random containment large isolation failure probability (large valves), and CDF Total = total plant-specific core damage frequency, which is obtained from plant specific PRA.
(a) By the letter dated February 6, 2006,10 NRC approved conversion of BVPS-1 and BVPS-2 containments from sub-atmospheric to atmospheric operating condition. Discuss the impacts of operating under atmospheric condition on this application.
10 ADAMS Accession No. ML060100325.
(b) As the LAR, submitted by letter dated August 12, 2013,11 for extension of the Type A test interval for similar sub-atmospheric containments at Surry Power Station did not assume a zero frequency per year for these Class 2 sequences, describe the screening criteria used to analyze containment penetrations > 2-inch diameter that resulted in screening out all these containment penetrations.
(c) Using the guidance in EPRI TR-1009325, Revision 2, calculate F Class 2 and show how the calculated F Class 2 will change the plant specific risk assessment results (reported in Table 6-5 of Attachments 3 and 4 to the LAR). If PROB large CI is assumed to be zero, explain why this failure probability is zero.
SCVB RAI 1 In accordance with Option B - Performance-Based Requirements, Subsection V.B. Implementation, of 10 CFR Part 50, Appendix J, states, in part, that, regulatory guides or other implementation documents used by a licensee to develop a performance-based leakage-testing program must be included, by general reference, in the plant technical specifications. The submittal for technical specification revisions must contain justification, including supporting analyses, if the licensee chooses to deviate from methods approved by the Commission and endorsed in a regulatory guide.
Enclosure Attachments1 and 2 (Mark-up and Re-typed Change of Technical Specifications) of LAR include reference to NEI 94-01, Revision 3-A. However, there are certain conditions and limitations contained in NEI 94-01, Revision 2-A that were not incorporated in NEI 94-01, Revision 3-A. To accommodate for this omission, the NRC staff recommend that licensees reference in their technical specifications both NEI 94-01, Revision 3-A, and the conditions and limitations specified in NEI 94-01, Revision 2-A.
Please include a reference to the conditions and limitations of NEI 94-01, Revision 2-A, or provide justification for omitting any reference to NEI 94-01, Revision 2-A, as part of the proposed changes to Technical Specifications 5.5.12-a.
11 ADAMS Accession No. ML13232A042.