RS-12-205, Supplement to Fifth Inservice Inspection Interval Relief Request I5R-02

Supplement to Fifth Inservice Inspection Interval Relief Request I5R-02

ML12333A263
Person / Time
Site:	Dresden, Quad Cities
Issue date:	11/28/2012
From:	Simpson P Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-12-205
Download: ML12333A263 (3)

Text

RS-12-205 10 CFR 50.55a November 28, 2012 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket Nos. 50-237 and 50-249 Quad Cities Nuclear Power Station, Units 1 and 2 Renewed Facility Operating License Nos. DPR-29 and DPR-30 NRC Docket Nos. 50-254 and 50-265

Subject:

Supplement to Dresden Nuclear Power Station and Quad Cities Nuclear Power Station Fifth Inservice Inspection Interval Relief Request 15R-02

References:

1. Letter from D. M. Gullott (Exelon Generation Company, LLC) to U.S. NRC, "Dresden Nuclear Power Station, Units 2 and 3, Fifth Interval Inservice Inspection Program Plan and Relief Requests," dated September 28, 2012

2. Letter from D. M. Gullott (Exelon Generation Company, LLC) to U.S. NRC, "Quad Cities Nuclear Power Station, Units 1 and 2, Fifth Interval Inservice Inspection Program Plan and Relief Requests," dated September 28, 2012 In References 1 and 2, Exelon Generation Company, LLC (EGC) submitted relief requests associated with the fifth inservice inspection (ISI) interval for Dresden Nuclear Power Station, Units 2 and 3, and Quad Cities Nuclear Power Station, Units 1 and 2, respectively. On November 15, 2012, in a conference call between the NRC and EGC, the NRC provided results of their acceptance review of relief request 15R-02, and discussed information that is needed to complete the acceptance review. The attachment provides the requested information.

November 28, 2012 U.S. Nuclear Regulatory Commission Page 2 There are no regulatory commitments contained in this letter. Should you have any questions concerning this letter, please contact Mr. Kenneth M. Nicely at (630) 657-2803.

Attachment:

Supplemental Information Regarding Relief Request 15R-02 cc: NRC Regional Administrator, Region III NRC Senior Resident Inspector, Dresden Nuclear Power Station NRC Senior Resident Inspector, Quad Cities Nuclear Power Station

ATTACHMENT Supplemental Information Regarding Relief Request 15R-02 NRC Request The licensee indicates that the risk impact assessment was completed as part of the original baseline RI-ISI program. The submittal further states that the change in risk was re-assessed, for the fifth interval, using the initial 1989 Edition, No Addenda ASME Section XI program. The licensee; however, did not provide the risk results that justifies that the acceptance criteria is met for the fifth interval. The acceptance criteria is described in Regulatory Guides 1.174 and 1.178. The licensee should provide the risk results from the assessment that was made by comparing the proposed ISI program to the initial Section XI requirements.

Response

As part of updating the risk informed inservice inspection (RISI) analysis for the fifth inservice inspection (ISI) intervals for Dresden Nuclear Power Station (DNPS), Units 2 and 3, and Quad Cities Nuclear Power Station (QCNPS), Units 1 and 2, the risk impact assessments were updated to confirm the changes in risk remained within the acceptance guidelines. The assessment methodology was not changed, and the change in risk was re-assessed using the latest element selection for the fifth interval RISI program. This risk impact assessment was completed as part of the initial RISI program as a comparison of the pre-RISI Section XI program to the RISI program. This process has been maintained as part of the RISI living program and has been updated with each revision of the station RISI report performed to date.

Based on the fifth interval update of this risk impact assessment, the change in risk from the pre-RISI Section XI program to the fifth interval RISI program was within the 1.00E-06 and 1.00E-07 acceptance criteria for delta-core damage frequency (delta-CDF) and delta-large early release frequency (delta-LERF), respectively, as described in Regulatory Guide 1.174, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis." Further, the change in risk was also calculated at the system level based on the Electric Power Research Institute (EPRI) RISI methodology, and all systems were confirmed acceptable. The delta-CDF and delta-LERF values for DNPS, Units 2 and 3, and QCNPS, Units 1 and 2, are listed in the following table.

Change in Risk from Pre-RISI Section Xl Program to Fifth Interval RiSrI Program Station Delta-CDF Delta-LERF DNPS Unit 2 4.61 E-09 2.03E-09 DNPS Unit 3 2.99E-09 9.89E-10 QCNPS Unit 1 3.11E-10 1.43E-09 QCNPS Unit 2 1.74E-09 2.08E-09 Page 1