ML080940215

RR 13R-01, Associated with the Third 10-Year Interval

ML080940215
Person / Time
Site:	LaSalle
Issue date:	04/29/2008
From:	Russell Gibbs, Russell Gibbs NRC/NRR/ADRO/DORL/LPLIII-2
To:	Pardee C Exelon Generation Co
Sands S,NRR/DORL, 415-3154
References
TAC MD5457, TAC MD5458
Download: ML080940215 (6)

Text

April 29, 2008 Mr. Charles G. Pardee Chief Nuclear Officer and Senior Vice President Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

LASALLE COUNTY STATION, UNITS 1 AND 2 - RELIEF REQUEST I3R-01, ASSOCIATED WITH THE THIRD 10-YEAR INTERVAL FOR LASALLE COUNTY STATION, UNITS 1 AND 2 (TAC NOS. MD5457 AND MD5458)

Dear Mr. Pardee:

By letter to the Nuclear Regulatory Commission (NRC), dated April 30, 2007 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML071280395), as supplemented by letter dated February 1, 2008 (ADAMS Accession No. ML080320580), Exelon Generation Company LLC (the licensee), submitted a Relief Request (RR) for the third 10-year interval inservice inspection (ISI) plan for LaSalle County Station (LSCS), Units 1 and 2. The licensee requested relief from the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI requirements for the selection and examination of Class 1 and 2 piping welds. The RR I3R-01, submitted by the licensee, proposes as an alternative to the ASME Code, to use the methodology contained in Electric Power Research Institute Topical Report 112657, Revision B-A. The NRC staff has approved this methodology in a safety evaluation dated October 28, 1999.

On September 12, 2007, NRC granted relief requests to LSCS for its third 10-year interval ISI plan, dated April 30, 2007, for RR Nos. I3R-03, I3R-04, I3R-08, I3R-00, and I3R-10 (ADAMS Accession No. ML072550452).

The licensee had requested, and received, relief for LSCS for the second 10-year ISI interval.

The licensee is requesting the same risk-informed (RI) ISI RR for the third 10-year interval. The NRC staff has evaluated the licensees RI-ISI RR for the third 10-year interval and finds that the licensee has addressed the necessary issues to demonstrate compliance with regulatory-related requirements and has provided sufficient assurance that the proposed RI-ISI program provides an acceptable level of quality and safety.

The RR is authorized for the third 10-year interval which ends on September 30, 2017.

Sincerely,

/RA/

Russell Gibbs, Chief Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-374

Enclosure:

Safety Evaluation cc w/encl: See next page

ML080320580), Exelon Generation Company LLC (the licensee), submitted a Relief Request (RR) for the third 10-year interval inservice inspection (ISI) plan for LaSalle County Station (LSCS), Units 1 and 2. The licensee requested relief from the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI requirements for the selection and examination of Class 1 and 2 piping welds. The RR I3R-01, submitted by the licensee, proposes as an alternative to the ASME Code, to use the methodology contained in Electric Power Research Institute Topical Report 112657, Revision B-A. The NRC staff has approved this methodology in a safety evaluation dated October 28, 1999.

On September 12, 2007, NRC granted relief requests to LSCS for its third 10-year interval ISI plan, dated April 30, 2007, for RR Nos. I3R-03, I3R-04, I3R-08, I3R-00, and I3R-10 (ADAMS Accession No. ML072550452).

The licensee had requested, and received, relief for LSCS for the second 10-year ISI interval.

The licensee is requesting the same risk-informed (RI) ISI RR for the third 10-year interval. The NRC staff has evaluated the licensees RI-ISI RR for the third 10-year interval and finds that the licensee has addressed the necessary issues to demonstrate compliance with regulatory-related requirements and has provided sufficient assurance that the proposed RI-ISI program provides an acceptable level of quality and safety.

The RR is authorized for the third 10-year interval which ends on September 30, 2017.

Sincerely,

/RA/

Russell Gibbs, Chief Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-374

Enclosure:

Safety Evaluation cc w/encl: See next page DISTRIBUTION:

PUBLIC LPL3-2 R/F RidsNrrAdes RidsNrrOd RidsAcrsAcnw&mMailCenter RidsOgcRp RidsNrrLAEWhitt RidsNrrDorlLpl3-2 RidsNrrPMSSands RidsRgn3MailCenter RidsNrrDraApla JAdams, EDO Region III Adams Accession No.: ML080940215 *SE Dated NRR-106 *w/corrections OFFICE LPL3-2/PM LPL3-2/LA DRA/APLA/BC OGC* LPL3-2/BC NAME SSands EWhitt MRubin* JBiggins RGibbs DATE 04 /29/08 04 /29/08 03 / 04 /08 04 / 16 /08 04 /29/08 LaSalle County Station, Units 1 and 2 cc:

Corporate Distribution Exelon Generation Company, LLC Via e-mail LaSalle Distribution Exelon Generation Company, LLC Via e-mail LaSalle Resident Inspector U.S. Nuclear Regulatory Commission Via e-mail Phillip P. Steptoe, Esquire Sidley and Austin Via e-mail Assistant Attorney General Chicago, IL 60603 Via e-mail Chairman LaSalle County Board Via e-mail Attorney General Via e-mail Chairman Illinois Commerce Commission Via e-mail Illinois Emergency Management Agency Division of Disaster Assistance &

Preparedness Via e-mail Robert Cushing, Chief, Public Utilities Division Illinois Attorney General's Office 100 W. Randolph Street Chicago, IL 60601

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RELIEF REQUEST NO. I3R-01, ASSOCIATED WITH THE THIRD 10-YEAR INSERVICE INSPECTION INTERVAL EXELON GENERATION COMPANY, LLC LASALLE COUNTY STATION, UNITS 1 AND 2 DOCKET NOS. 50-373, AND 50-374

1.0 INTRODUCTION

By letter to the Nuclear Regulatory Commission (NRC, the Commission) dated April 30, 2007 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML071280395), as supplemented by letter dated February 1, 2008 (ADAMS Accession No. ML080320580), Exelon Generation Company, LLC (the licensee), requested approval of alternate risk-informed inservice inspection (RI-ISI) selection and examination criteria at the LaSalle County Station (LSCS), Units 1 and 2. The licensees RI-ISI program is an alternative pursuant to Section 50.55a(a)(3)(i) of Title 10 of the Code of Federal Regulations (10 CFR).

The scope of the alternate RI-ISI program, I3R-01, is applicable to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, 2001 Edition through the 2003 Addenda, Class 1 and 2 piping, Categories B-F, B-J, C-F-1, and C-F-2 piping welds.

The NRC staff had approved a RI-ISI program for use during the second 10-year interval which started on November 23, 1994 and ended on October 28, 2007 for LSCS, Unit 1; and from October 17, 1994, to July 4, 2007, for LSCS, Unit 2 (ADAMS Accession No. ML013610078).

The licensee is proposing to extend the RI-ISI to the new, third 10-year interval which starts on October 1, 2007, and ends on September 30, 2017, for both Units 1 and 2.

By letter dated September 22, 2006 (ADAMS Accession No. ML062720153), the licensee informed the NRC of their intention to synchronize the ten-year ISI intervals between LSCS Units 1 and 2 for ASME Code classes 1, 2, and 3. The implementation would be based on the provisions of ASME Section XI paragraph IWA-2430 Inspection Intervals. In accordance with Program B, each inspection interval may be reduced or extended up to one year. Since the provisions of ASME Section XI paragraph IWA-2430(d) were met, a relief request to extend the interval in accordance with 10 CFR 50.55a, Codes and Standards, paragraph (a)(3)(i) was not required.

2.0 REGULATORY EVALUATION

Section 50.55a(g) of 10 CFR requires that ISI of the ASME Code Class 1, 2, and 3 components be performed in accordance with Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components and applicable addenda, except where specific relief has been granted by

the Commission pursuant to 10 CFR 50.55a(g)(6)(i). The regulation 10 CFR 50.55a(a)(3) states in part, that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if the licensee demonstrates that the proposed alternatives would provide an acceptable level of quality and safety, or if the specified requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

The proposed program is developed consistent with the staff approved RI-ISI process and methodology delineated in Electric Power Research Institute (EPRI) (TR)-112657, Revision B-A, Revised Risk-Informed Inservice Inspection Evaluation Procedure as approved by the NRC staff for use during the second interval. The ISI program retains the fundamental requirements of the ASME Code, such as inspection methods, acceptance guidelines, pressure testing, corrective measures, documentation requirements and quality control requirements.

The NRC staff reviewed the proposed RI-ISI program based on guidance and acceptance criteria provided in the following documents:

• EPRI TR-112657, Revision B-A, Revised Risk-Informed Inservice Inspection Evaluation Procedure, Final Report, December 1999.

• Regulatory Guide 1.174, Revision 1, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant Specific Changes to the Licensing Basis, Revision 1, U.S. NRC, November 2002.

• NRC Regulatory Guide 1.178, Revision 1, An Approach for, Plant-Specific, Risk-Informed Decisionmaking for Inservice Inspection of Piping, U.S. NRC, September 2003.

• NUREG-0800, Chapter 3.9.8, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants, Risk-Informed Inservice Inspection of Piping, U.S.

NRC, September 2003.

3.0 TECHNICAL EVALUATION

The licensee is requesting relief that would permit continued use of a previously approved RI-ISI program plan in the third 10-year ISI interval instead of the ASME Code,Section XI program.

An acceptable RI-ISI program plan is expected to meet the five key principles of risk-informed decisionmaking, discussed in Regulatory Guide (RG) 1.174 and RG 1.178. These principles are:

1) The proposed change meets the current regulations unless it is explicitly related to a requested exemption or rule change.

2) The proposed change is consistent with the defense-in-depth philosophy.

3) The proposed change maintains sufficient safety margins.

4) When proposed changes result in an increase in core damage frequency and/or large early release frequency (LERF), the increases should be small and consistent with the intent of the Commissions Safety Goal Policy Statement.

5) The impact of the proposed change should be monitored by using performance measurement strategies.

The first principle is met in this RR because an alternative ISI program may be authorized pursuant to 10 CFR 50.55a(3)(i) and therefore, an exemption request is not required.

The second and third principles require assurance that the alternative program is consistent with the defense-in-depth philosophy and that sufficient safety margins are maintained, respectively.

The methodology used to develop the third 10-year RI-ISI program interval is unchanged from the methodology approved for use in the second 10-year RI-ISI program interval. Assurance that the second and third principles are met is based on the application of the approved methodology and not on the particular inspection locations selected. Therefore, the second and third principles are met.

The fourth principle requires an estimate of the change in risk, and the change in risk is dependent on the number and location of inspections in the proposed ISI program compared to the number and location of inspections that would be inspected using the requirements of ASME Code,Section XI. The topical report EPRI TR-112657 requires that a change in risk measurement must consider the discontinuance of ASME Code required inspections, as well as any new inspections resulting from the application of its methodology. The licensee states in Reference 2, that a complete risk evaluation following the EPRI methodology was performed in 2007. The update was completed as part of the living program process using the current PRA model and the latest element selections. The licensee reports the changes in CDF and LERF for LSCS, Unit 1 to be 6.89E-9/yr and 4.76E-9/yr. For LSCS, Unit 2, the estimate change in CDF and LERF are 8.40E-9/yr and 6.39E-9/yr. The licensee also reported the system level changes for all the systems included in the scope of the submittal. All of the estimated changes in risk are below the EPRI guideline for acceptable estimated changes in CDF and LERF.

The fifth principle of RI decisionmaking requires that the impact of the proposed change should be monitored by using performance measurement strategies. In addition to the complete risk evaluation described above, the licensee states that the evaluation and ranking procedure including the consequence evaluation and degradation mechanism assessment are continually applied to maintain the risk categorization and element selection methods of EPRI TR-112657.

These portions of the program are also reevaluated as major revisions of the site PRA that occur and modifications to the plant configuration were made on April 30. 2007. Thus, the program continues to be a living program and therefore satisfies the fifth principle.

Based on the above discussion, the NRC staff concludes that the five key principles of RI decision making are satisfied by the licensees proposed third 10-year RI-ISI program, and, therefore, the proposed program for the third 10-year ISI interval is acceptable.

4.0 CONCLUSION

Based on the information provided in the licensees submittals, the NRC staff has determined that the proposed alternative provides an acceptable level of quality and safety, and therefore the proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the third 10-year ISI inspection interval at LSCS.

Principal Contributor: D. Chung, NRR Date: April 29, 2008