ML093521673
| ML093521673 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 12/18/2009 |
| From: | John Hughey Plant Licensing Branch 1 |
| To: | Exelon Corp |
| Hughey J, NRR/DORL, 301-415-3204 | |
| Shared Package | |
| ml093521664 | List: |
| References | |
| Download: ML093521673 (2) | |
Text
DRAFT REQUEST FOR ADDITIONAL INFORMATION RELATED TO LICENSE AMENDMENT REQUEST FOR ONE-TIME FIVE-YEAR CONTAINMENT TYPE A INTEGRATED LEAK RATE TEST (ILRT) INTERVAL EXTENSION PEACH BOTTOM ATOMIC POWER STATION - UNIT 2 DOCKET NO. 50-277 By letter to the Nuclear Regulatory Commission (NRC) dated August 28, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML092440053), Exelon Generation Company, LLC, (Exelon) submitted a License Amendment Request (LAR) for Peach Bottom Atomic Power Station (PBAPS), Unit 2. The submittal seeks to revise Technical Specification 5.5.12 to reflect a one-time extension of the containment Type A Integrated Leak Rate Test (ILRT) from 10 to 15 years. The one-time extension would require a Type A ILRT to be performed no later than October of 2015. The NRC staff has reviewed Exelon's submittal and determined that additional information, as described below, is needed to complete the review.
seVB Branch Questions RAI-01 Type B and Type C Combined Leakage Rate Totals:
In your August 28, 2009, License Amendment Request, Attachment 1, Page 4, you provide the results of 1991 and 2000 ILRTs. On Page 6 you provide the Type Band C Test leakage totals for 2006 and 2008 refueling outages.
RAI-01.1:
Provide the Type B and Type C combined leakage rate totals associated with the ILRT historical test results provided for the 1991,2000,2006 and 2008 refueling outages.
RAI-01.2:
Provide the Type B and Type C combined leakage rate totals associated with the ILRTs performed during all other refueling outages since 2000.
RAI-02 Containment Pressure Credit For Pump Net Positive Suction Head:
Your August 28, 2009, License Amendment Request indicates that the ILRT interval does not impact on Core Damage Frequency (CDF). Section 5.2.4.3.2 of the Peach Bottom Updated Final Safety Analysis Report (UFSAR) indicates that the net positive suction pressure available (NPSHa) for the Core Standby Cooling System (CSCS) pumps takes, in part, credit for the pressure within the containment.
RAI-02.1:
Please address the impact of the proposed ILRT test interval extension on CDF given the assumption of reliance on containment pressure for CSCS NPSHa.
(Please see Section 3.2.2 of the NRC staff Safety Evaluation issued on June 25, 2008, (ADAMS Accession Number ML081140105) for additional information related to evaluating containment over-pressure credit impact using EPRI Report 1009325, Revision 2.)
- 2 APLA Branch Questions RAI-03 Steel Liner Corrosion Events:
The assessment of corrosion-induced leakage of the steel liner in Section 4.4 of Attachment 4 was based on three observed corrosion events (at Oyster Creek, North Anna 2 and Brunswick Unit 2). There have been additional instances of liner corrosion that are relevant to this assessment, including a recent finding at Beaver Valley Unit 1 (LER 2009-003-00).
RAI-03.1:
Provide a more complete accounting of all observed corrosion events relevant to the Peach Bottom Unit 2 containment, and an evaluation of the impact on risk results when all relevant corrosion events are included in the risk assessment.
RAI-04 PRA Technical Adequacy:
The discussion of PRA Technical Adequacy in Section A.2.2 of Appendix A to Attachment 4 includes a list of assessments of technical capability of the PBAPS PRA models.
RAI-04.1:
Please identify who conducted the 2004 gap analysis, and who performed the 2006 assessment of the extent to which previously identified gaps had been addressed.
RAI-05 GAP Analysis:
Table A-2 of Attachment 4, "Status of Identified Gaps to Capability Category II of the ASME PRA Standard" indicates that Gap #25, related to test and maintenance pre-initiator errors, is "not significant" for this application.
RAI-05.1:
Describe and justify the basis for the statement that "Pre-initiator human actions do not contribute significantly to the risk significance results for this application", given that a detailed process was not employed for identifying and screening test and maintenance pre-initiators. Discuss whether this gap includes the modeling of pre-initiator errors related to test and maintenance of containment isolation valves, and if so, how resolution of the gap would impact the risk results for this license amendment request.