ML083190494
| ML083190494 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 12/01/2008 |
| From: | Mark Kowal Plant Licensing Branch 1 |
| To: | Polson K Nine Mile Point |
| Guzman R, NRR/DORL, 415-1030 | |
| References | |
| 2ISI-007, 2ISI-009, TAC MD7688, TAC MD7690 | |
| Download: ML083190494 (13) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 December 1, 2008 Mr. Keith J. Polson Vice President Nine Mile Point Nine Mile Point Nuclear Station, LLC P.O. Box 63 Lycoming, NY 13093
SUBJECT:
NINE MILE POINT NUCLEAR STATION, UNIT NO.2 - RELIEF REQUESTS 21SI-007 AND 21SI-009 FOR THIRD 10-YEAR INSERVICE INSPECTION (lSI)
INTERVAL (TAC NOS. MD7688 AND MD7690)
Dear Mr. Polson:
By letter dated December 14, 2007, as supplemented by letters dated January 25, June 30, July 18, and July 31,2008, Nine Mile Point Nuclear Station, LLC (NMPNS, the licensee) submitted 2 Relief Requests (RRs), 21SI-007 and 2ISI-009, for Nine Mile Point, Unit NO.2 (NMP2) proposing alternatives to the requirements of Title 10 of the Code of Federal Regulations, Part 50, Section 55a (10 CFR 50.55a), concerning the requirements of the American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code) for its third 10-year lSI Program Plan.
The Nuclear Regulatory Commission (NRC) staff has reviewed NMPNS's regulatory and technical analysis in support of its RRs for 21SI-007 and 2ISI-009. The application dated December 14, 2007, also requested 6 other RRs for the third 10-year lSI interval which were based on impracticality in accordance with 10 CFR 50.55a(g)(5)(iii). By letter dated July 31, 2008, NMPNS withdrew from NRC review, the 6 impracticality-based RRs (2ISI-002, 21SI-003, 21SI-004, 2ISI-005, 21SI-006, and 2ISI-008). The NRC staff concurs with the licensee that RRs based on impracticality should be submitted for NRC review after attempts have been made to perform the subject examinations. Additionally, these requests are to be submitted to and approved by the NRC not later than 12 months after the end of the associated 1O-year lSI interval pursuant to 10 CFR 50.55a(g)(5)(iv).
Based on the information provided by NMPNS, the NRC staff has concluded that NMPNS's proposed alternatives for 21SI-007 and 21SI-009 provide an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3), the NRC staff authorizes the proposed alternatives for 21SI-007 and 21SI-009 for I\IMP2 for the third 1O-year lSI interval.
NMP2 is currently in its third 1O-year interval, which began on April 5, 2008, and ends on April 4, 2018. The applicable lSI Code of record for the third 1O-year interval is the 2001 Edition with the 2003 Addenda of the ASME Code,Section XI.
K. Polson -2 The NRC staffs safety evaluation is enclosed. If you have any questions, please contact Richard Guzman, at (301) 415-1030.
Sincerely, Mark G. Kowal, Chief Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-410
Enclosure:
As stated cc w/encl: Distribution via Listserv
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR RELIEF 21SI-007 AND 21SI-009 FOR THIRD 10-YEAR INSERVICE INSPECTION INTERVAL NINE MILE POINT NUCLEAR STATION, LLC NINE MILE POINT NUCLEAR STATION, UNIT NO.2 DOCKET NUMBER 50-410
1.0 INTRODUCTION
By letter dated December 14, 2007 (Agencywide Documents Access and Management Systems (ADAMS) Accession No. ML073650155) as supplemented by letters dated January 25 (ML080250410), June 30 (ML081840022), JUly 18 (ML082000483), and July 31, 2008 (ML082130565), Nine Mile Point Nuclear Station (NMPNS), LLC (the licensee) submitted 2 relief requests (RRs) ISI-007 and 21SI-009 for Nine Mile Point, Unit 2 (NMP2). 21SI-007 requests to extend the Risk-Informed Inservice Inspection (RI-ISI) Program Plan for NMP2 for the third 10 year lSI interval. The NMP2 RI-ISI program was initially submitted to the Nuclear Regulatory Commission (NRC) staff in a letter dated October 16, 2000 (Reference 1), during the second 10 year lSI interval, beginning with the second inspection period, and supplemented in a letter dated April 12, 2001 (Reference 2). The NMP2 RI-ISI program was reviewed and approved by the NRC for use in the second 10-year lSI interval in a letter dated May 31, 2001 (Reference 3).
The licensee considered relevant information since the RI-ISI program was implemented during the second interval to update the RI-ISI program. The licensee's December 14, 2007, submittal requests authorization to implement the proposed RI-ISI program for the third 10-year lSI interval.
RR-2ISI-009 proposes an alternative to certain requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) examination requirements associated with the third 10-year lSI interval at NMP2. Specifically, NMPNS requests relief from ASME Code volumetric examination requirements for selected welds with less than essentially 100% coverage. The request is for the third 1O-year lSI interval which began April 5, 2008, and scheduled to end April 4, 2018.
2.0 REGULATORY REQUIREMENTS Paragraph 50.55a(g) of Title 10 of the Code of Federal Regulations (10 CFR) specifies that lSI of nuclear power plant components shall be performed in accordance with the requirements of the ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). 10 CFR 50.55a(a)(3) states that alternatives to the Enclosure
-2 requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the pre service examination requirements, set forth in the ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of components. The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the requirements of the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The applicable lSI Code of record for the third 1O-year interval for NMP2 is the 2001 Edition with the 2003 Addenda of the ASME Code,Section XI.
Alternatives to requirements may be authorized by the NRC pursuant to 10 CFR 50.55a(a)(3)(i) or 10 CFR 50.55a(a)(3)(ii). In proposing alternatives, the licensee must demonstrate that:
(1) the proposed alternatives would provide an acceptable level of quality and safety or (2) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Pursuant to 10 CFR 50.5a(g)( 4)(iv),
lSI items may meet the requirements set forth in subsequent editions and addenda of the ASME Code that are incorporated by reference in 10 CFR 50.55a(b), subject to the limitations and modifications listed therein, and subject to Commission approval. Portions of editions and addenda may be used provided that all related requirements of the respective editions and addenda are met.
The licensee's RI-ISI program, as outlined in its letter dated July 18, 2008, was developed in accordance with the methodology contained in the Electric Power Research Institute's (EPRl's)
Topical Reports (TR) EPRI TR-112657, Rev. B-A, "Revised Risk-Informed Inservice Inspection Evaluation Procedure, Final Report," (Reference 4) and EPRI TR-1006937, Rev. O-A, "Extension of EPRI Risk Informed lSI Methodology to Break Exclusion Region Programs,"
(Reference 5) which were reviewed and approved by the NRC staff, as supplemented by ASME Code Case N-578-1 (Reference 6). The NMPNS-2 RI-ISI program is an alternative pursuant to 10 CFR 50.55a(a)(3)(i). The program scope will be implemented as an alternative to the ASME Code, 2001 Edition through the 2003 Addenda,Section XI examination program for Class 1 Examination Categories B-F and B-J, Class 2 Examination Categories C-F-1 and C-F-2, and Intergranular Stress Corrosion Cracking (IGSCC) Examination Category "A" piping welds.
The information provided by the licensee in support of the request has been evaluated and the basis for disposition is documented below.
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3.0 TECHNICAL EVALUATION
3.1 Relief Request 21SI-007 3.1.1 Component Identification System: Various ASME Code Class 1 and 2 Systems Code Class: ASME Code Class 1 and 2 Component
Description:
ASME Code Class 1 and 2 Piping Welds Components Affected:
Weld Description Code Code Item Number Numbers Category Various ASME Code Class 1 Piping B-F B5.10, B5.20, B5.30, Welds B5.100, B5.110, B5.120 Various ASME Code Class 1 Piping B-J B9.11, B9.21, B9.31, B9.32, Welds B9.40 Various ASME Code Class 2 Piping C-F-1 C5.11, C5.21, C5.30, C5.40 Welds Various ASME Code Class 2 Piping C-F-2 C5.51, C5.61, C5.70, C5.81 Welds Various IGSCC Category A Piping A N/A Welds 3.1.2 Code Requirement for which Relief is Requested ASME Code,Section XI, Subarticle IWB-2500 and IWC-2500, Tables IWB-2500-1 and IWC-2500-1, Examination Categories B-F, B-J, C-F-1, and C-F-2, "Pressure Retaining Welds in Piping," and IGSCC Category "A" welds.
3.1.3 Licensee's Basis for Relief Pursuant to 10 CFR 50.55a(a)(3), relief is requested for the above-stated piping welds. The initial NMP2 RI-ISI Program was submitted during the second inspection period of the second 10-year lSI interval. This initial RI-ISI program was developed in accordance with EPRI TR 112657, Revision B-A, as supplemented by Code Case N-578-1. The program was approved for use by the NRC via Safety Evaluation as transmitted to the licensee on May 31,2001 (Reference 3). In its December 14, 2007, submittal, the licensee states that the RI-ISI program has been updated and continues to meet EPRI TR-112657 and Regulatory Guide (RG) 1.174 (Reference 7) risk acceptance criteria.
3.1.4 Licensee's Proposed Alternative to Code In the December 14, 2007, submittal, the licensee states that:
NMPNS will continue to implement the Risk-Informed Inservice Inspection Program in accordance with ASME Code Case N-578-1, "Risk-Informed Requirements for Class 1,
- 4 2, and 3 Piping, Method B Section XI, Division 1." In addition, NMPNS intends to perform additional examinations required due to the identification of flaws, which are determined to exceed the acceptance standards, during the current refueling outage prior to the units return to service.
The ultrasonic examination volume to be used based on degradation mechanism and component configuration will be the examination figures specified in Section 4 of EPRI TR-112657.
The licensee states that the ASME Code,Section XI required minimum percentage (50%) was completed in the second period of the second lSI interval and the remaining fifty percent (50%)
of the RI-ISI program welds were completed by the end of the third inspection interval. This relief request is to align the RI-ISI Interval and the Code Year with the Third Interval lSI program.
One hundred percent (100%) of the RI-ISI Program weld examinations will be completed in the third Inspection Interval.
The June 30, 2008, supplement provides additional information regarding the licensee's use of ASME Code Case N-578-1. The supplement includes discussion regarding the two items of concern articulated in RG 1.193 (Reference 8) related to use of ASME Code Case N-578-1, those being: (a) addressing existing augmented/other inspection programs, and (b) system-level risk change guidance.
3.1.5 NRC Staff's Evaluation In its submittal, the licensee requested relief pursuant to 10 CFR 50.55a(a)(3)(i). The licensee sought relief from the requirements of ASME Code,Section XI to utilize a RI-ISI Program at NMP2 during the third 10-year lSI interval. The third interval RI-ISI Program is a continuation of the current application with no changes to the evaluation methodology as currently implemented.
As discussed in Reference 1, the lSI program, approved for use in the second 1O-year interval, did not contain any deviations from the EPRI TR-112657 methodology.
In its request for additional information (RAI), the NRC staff noted that per RG 1.193 (Reference 8), Code Case N-578-1 is listed as an unacceptable ASME Code,Section XI Code Case. The staff asked the licensee to provide a justification for use of this code case. In response to this request, the licensee stated in its June 30, 2008, supplement that they recognized RG 1.193 does not allow for the generic use of ASME Code Case N-578-1, and that rather, they were requesting its use on a plant-specific basis. The licensee goes on to address the two concerns raised in RG 1.193 regarding this code case. For the first concern (Code Case N-578-1 does not address existing augmented or other inspection programs), the licensee states, "the EPRI TR-112657 methodology is designed to be integrated with existing augmented examination programs ... the NMPNS approach for existing augmented inspection programs for Class 1 and Class 2 piping systems is consistent with the EPRI TR-112657 guidelines ... " Specifically,
- The augmented inspection program for IGSCC Category A welds is incorporated into the RI lSI program;
- The weld inspections associated with IGSCC Categories B-G continue to be inspected in accordance with the plant program under Generic Letter (GL) 88-01 (Reference 9) and NUREG-0313 (Reference 10) guidance; and
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- The augmented inspection program implemented in response to GL 89-08 (Reference 11) is unaffected by the RI-ISI program.
The NRC staff has reviewed the pertinent sections of EPRI TR-112657 and finds that the licensee is addressing the augmented inspection program in accordance with the guidance provided by that report; therefore, the staff is satisfied that the licensee is appropriately addressing the first concern of RG 1.193 regarding augmented inspection programs.
The second concern noted in RG 1.193 is that "Code Case N-578-1 does not provide system-level guidelines for changes in risk evaluation to ensure that the risk from individual system failures will be kept small and dominant risk contributors will not be created." The staff's evaluation of EPRI TR-112657 found the scope of the EPRI methodology to be acceptable since it was consistent with guidance provided in RG 1.178 and Standard Review Plan (SRP) Chapter 3.9.8. Furthermore, the staff finds that conformance to the system-level guidelines provides reasonable assurance that the risk from individual system failures will be kept small and dominant risk contributors will not be created. Conformance with the system-level guidelines provides assurance that the aggregate impact of possible further application of RI-ISI at any plant would not be expected to exceed the aggregate risk change guidelines in RG 1.174." The NMP2 RI-ISI program has been developed in accordance with the methodology contained in EPRI TR-112657; thus, the second concern noted in RG 1.193 has been addressed by the licensee. Therefore, the staff finds use of ASME Code Case N-578-1, in conjunction with EPRI TR-112657, as described in the licensee's submittal, to be acceptable.
An acceptable RI-ISI program plan is expected to meet the five key principles discussed in RG 1.178 (Reference 12), SRP Section 3.9.8 (Reference 13) and EPRI TR-112657, as stated below:
- 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 (CDF) or risk, the increases should be small and consistent with the intent of the Commission's 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 relief request because an alternative lSI 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. 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. The licensee stated that they are using the same methodology as the original submittal. Since the methodology used to develop the RI-ISI program for the third 10-year interval is unchanged from the methodology approved for development of the RI-ISI program used in the second 1O-year lSI interval, the second and third principles are met.
-6 The fourth principle requires an estimate of the change in risk. The change in risk estimate is dependent on the location of inspections in the proposed lSI program compared to the location of inspections that would be inspected using the requirements of ASME Code,Section XI. The NRC staff has previously determined that it is not necessary to develop a new deterministic ASME program for each new 1O-year interval, but instead, it is acceptable to compare the new proposed RI-ISI program with the last deterministic ASME program.
The licensee's December 2007 submittal states that, as part of the RI-ISlliving program, the delta risk assessment was re-evaluated to support Relief Request 2ISI-007. The licensee further states that the revised change in risk continues to meet the delta risk acceptance criteria of EPRI TR-112657. In lieu of providing a description of its living program, the licensee references the description of the living program in Section 4 of its October 16, 2000, submittal (Reference 1).
In the licensee's June 30, 2008 and July 18, 2008, responses to the staff's RAls, the licensee further clarified that the last RI-ISI program evaluation was performed in December 2005, following completion of the second period of the second 10-year lSI interval. The probabilistic risk assessment (PRA) model that was used for the December 2005 re-evaluation was the version current for the plant as of that time. The licensee further states that assessments of plant changes that occurred during 2006 and 2007 have not identified any PRA model or documentation changes that would have a significant impact on the proposed RI-ISI program.
As provided in a conference call on September 17,2008, and a subsequent e-mail from the licensee (ADAMS Accession No. ML082660914), the licensee described that in the re-evaluation performed by EPRI, a methodology was implemented to discriminate between mechanical crevices and electrochemical crevices. This EPRI enhanced crevice corrosion analysis, documented in a November 2005 EPRI Report (Reference 14) refined the degradation mechanism analysis and resulted in a determination that the crevice corrosion degradation mechanism was no longer applicable to reactor pressure vessel nozzles. Thus, there was a decrease in the number of overall weld locations to be inspected from 125 to 120. Based on the staff's assessment of this information, the staff finds that the fourth principle is met.
The fifth principle of risk-informed decisionmaking requires that the impact of the proposed change should be monitored by using performance measurement strategies. As described in Reference 1 and approved by the staff in Reference 3, the RI-ISI program is a living program that requires periodic updating. The analyses and changes reported by the licensee, as discussed above under principle number 4, demonstrate that the RI-ISI program is a living program that is being periodically updated, and therefore, the staff concludes that the fifth key principle is met.
As discussed above, the staff finds that the licensee has met the five key principles of risk informed decisionmaking discussed in RG 1.178 and SRP 3.9.8. Further, the staff finds the licensee's plant-specific implementation of ASME Code Case N-578-1 acceptable because the licensee has addressed the two concerns noted in RG 1.193 satisfactorily. Therefore, the staff finds the proposed alternative RI-ISI program for the third lSI interval acceptable.
-7 3.2 Relief Request 21SI-009 3.2.1 Component Identification Pump No. Weld Number 2CSH*P1 PW207 PW208 PW209 PW212 PW217 PW218 PW219 2CSL*P1 PW311 PW312 PW315 PW316 PW319 2RHS*P1A PW111A PW112A PW113A PW116A PW118A PW121A 2RHS*P1B PW111B PW112B PW113B PW116B .PW118B PW121B 2RHS*P1C PW111C PW112C PW113C PW116C PW118C PW121C 2ICS*P1 PW400 PW401 PW402 PW403 3.2.2 Code Requirement for which Relief is Requested Subarticle IWC-2500, Table IWC-2500-1, Examination Category C-C, Item C6.10 which requires essentially 100% surface examination of pump casing welds each inspection interval.
Subarticle IWC-2500, Table IWC-2500-1, Examination Category C-G, item C3.30 which requires 100% surface examination of pump welded attachments each inspection interval.
3.2.3 Licensee's Basis for Relief In accordance with the provisions of 10 CFR 50.55a, "Codes and standards," paragraph 10 CFR 50.55a(a)(3), the licensee requests relief from the requirements of ASME Code Section XI Subarticle IWC-2500, Table IWC-2500-1, Examination Category C-C, Item C6.10 which requires essentially 100% surface examination of pump casing welds each inspection interval; and Subarticle IWC-2500, Table IWC-2500-1, Examination Category C-G, item C3.30 which requires 100% surface examination of pump welded attachments each inspection interval.
The licensee has concluded that based on the permanent limitations and the percent of examination coverage achieved the relief is justified and efforts to increase coverage presents a hardship without a compensating increase in safety, in accordance with 10 CFR 50.55a(a)(3)(ii).
3.2.4 Licensee's Proposed Alternative to Code The licensee will continue to implement, to the maximum extent possible, the lSI examination requirements of IWC-2500, Table IWC-2500-1, Examination Category C-C, Item C6.10, which requires essentially 100% surface examination of pump casing welds each inspection interval; and Subarticle IWC-2500, Table IWC-2500-1, Examination Category C-G, Item C3.30 which requires 100% surface examination of pump welded attachments each inspection interval on welds of pumps that become accessible when disassembled for routine maintenance.
The pumps are installed in a concrete pit, thereby making the exterior of the casing welds and entire integral attachment welds inaccessible for surface examination. Examination of the casing welds would require either disassembly or removal from the pit. Examination of the integral attachment welds would require lifting the pump from the pit. The hardships associated with pump disassembly and lifting from the pit would far exceed any beneficial safety
-8 improvements that might be achieved by such an examination. For the integral attachments on pump ICS*P1, approximately 17% of each of the four welds is inaccessible. The pump design utilizes U-shaped attachments that limit access to the entire weld surface.
Since these pumps are subject to testing per ASME Operations and Maintenance (OM) Code, loss of integrity of the pump casing welds would be detected during quarterly pressure, differential, and flow rate testing. Failure of integral attachments welds would be detected by quarterly vibration measurements. Furthermore, pump casing integrity is verified during system leakage testing.
3.2.5 NRC Staff's Evaluation The ASIVIE Code,Section XI, Table IWC-2500-1, Items C3.30 (pump welded attachments) and C6.10 (pump casing welds) require essentially 100% surface examinations. The licensee requested that NRC re-authorize the use of the use of a previously authorized request for relief from the second 10-year lSI interval dated March 3, 2000 (ML003690414).
The pumps 2CSH*P1, 2CSL *P1, 2RHS*P1 A, 2RHS*P1 B, and 2RHS*P1 C are located in pits that are 4 feet in diameter and range from 11 feet to 27 feet deep as provided by response to Inspection and Enforcement (IE)Bulletin 79-15, "Deep Draft Pump Deficiencies," dated September 11, 1979 (see Reference 15). The pump casing welds (subject welds) are located below the mounting bolts which are located furthest from the pit opening access point.
Examination of the casing welds would require either pump disassembly and examination of the welds from the inside surface or pump removal from the pit for weld examination from the outside surface. Disassembly of the pump is an involved process that poses a risk of damaging the bearings, tie rod threads, impeller, and casing rings, and is difficult to examine with remote equipment from floor level or in the cramped pit space at the pump. The licensee considers the pump disassembly solely for the purpose of inspecting the weld surfaces a significant burden. In addition, these pumps are subjected to periodic inservice tests and leak detection that provide reasonable assurance for continued operational readiness.
Approximately, 83% of the 4 attachment welds to pump ICS*P1 are accessible for examination.
The inaccessible 17% of the pump-to-attachment welds are concealed behind the weld that attaches the pump to the attachment brackets and mounting plate. The accessible weld holding the pump and attachment bracket to the mounting plate provides the structural integrity necessary to hold the pump stationary. Access to the concealed 17% of the weld would necessitate changing the design of the pump or attachment bracket. The licensee considers that a design change and replacement of pump ICS*P1 in order to achieve access to the 17% of unexamined weld surface is an unnecessary burden because the surface examination of the weld attaching the bracket to the pump and mounting plate would reveal any significant structural integrity degradation.
The licensee's proposed alternative is to perform a surface examination on the pump casing welds and integral attachment welds when they become accessible during disassembling for routine maintenance or removal. The routine maintenance examinations should detect any significant degradation patterns, if present. Since these pumps are subjected to testing per ASME OM Code, loss of integrity of the pump casing welds would be detected during the quarterly pressure, differential, and flow rate testing. The failure of the inaccessible integral
-9 attachment welds would be revealed at the accessible attachment bracket welds and the attachment bracket welds to the mounting plate. Any weld failures would be detected by the quarterly vibration measurements. The achievable surface examinations, system leakage tests, vibration monitoring, and periodic tests will provide reasonable assurance of the structural integrity and operational readiness of the pump casing welds and attachment welds. Therefore, the staff finds the proposed alternative for the third 1O-year lSI interval acceptable for NMP2.
4.0 CONCLUSION
S Based on the review of the information provided in the licensee's submittals, the NRC staff concludes that the proposed alternative for 21SI-007 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 1O-year lSI inspection interval for NMP2.
The NRC staff also concludes that the licensee's proposed alternative for 21SI-009 provides reasonable assurance of structural integrity and that compliance with the ASME Code examination coverage requirements results in hardship without a compensating increase in the level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(ii), the licensee's proposed alternatives for relief requests 21SI-007 and 21SI-009 are authorized for the third 10-year lSI interval for I\JMP2.
All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
5.0 REFERENCES
- 1. Letter from Richard B. Abbott, Niagara Mohawk, to U.S. Nuclear Regulatory Commission, "Nine Mile Point Unit 2, Docket No. 50-410, NPF-69, Request for Authorization to Use Risk-Informed Inservice Inspection Alternative," dated October 16, 2000.
- 2. Letter from Richard B. Abbott, Niagara Mohawk, to U.S. Nuclear Regulatory Commission, "Nine Mile Point Unit 2, Docket No. 50-410, NPF-69, Response to Request for Additional Information Related to Request to Use Risk-Informed Inservice Inspection Alternative (TAC No. MB0297)," dated April 12, 2001.
- 3. Letter from U.S. Nuclear Regulatory Commission to J.H. Mueller, Niagara Mohawk Power Corporation, "Nine Mile Point Nuclear Station, Unit NO.2 - Approval to Use a Risk-Informed Inservice Inspection Program for the Second 10-Year Interval (TAC No.
MB0297)," dated May 31,2001.
- 4. EPRI TR-112657, Revision B-A, "Revised Risk-Informed Inservice Inspection Evaluation Procedure, Final Report," December 1999.
- 5. EPRI TR-1006937, Revision O-A, "Extension of EPRI Risk Informed lSI Methodology to Break Exclusion Region Programs," April 2002.
- 10
- 6. American Society of Mechanical Engineers (ASME) Code Case N-578-1, "Risk-Informed Requirements for Class 1, 2, or 3 Piping, Method B."
- 7. NRC Regulatory Guide 1.174, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis," November 2002.
- 8. NRC Regulatory Guide 1.193, "ASIVIE Code Cases Not Approved For Use," October 2007.
- 9. NRC Generic Letter 88-01, "NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping, "January 25, 1988.
- 10. NUREG-0313, "Technical Report on Material Selection and Processing Guidelines for BWR Coolant Pressure Boundary Piping," Revision 2, January 1988.
- 11. NRC Generic Letter 89-08, "Errosion/Corrosion-Induced Pipe Wall Thinning," May 2, 1989.
- 12. NRC Regulatory Guide 1.178, "An Approach for Plant-Specific Risk-Informed Decision Making: Inservice Inspection of Piping," September 2003.
- 13. NRC NUREG-0800, Chapter 3.9.8, "Standard Review Plan for Trial Use for the Review of Risk-Informed Inservice Inspection of Piping," September 2003.
- 14. EPRI Report, "Enhanced Crevice Corrosion Criteria in RI-ISI Evaluations," Report No.
1011945, November 2005.
- 15. E-mail from D. Vandeputte to R. Guzman, "Nine Mile Point Unit 2 E-mail and supplemental information re: Third lSI Interval Relief Request 2ISI-009," October 14, 2008. ADAMS Accession No. ML082900561.
Principal Contributors: C. Nove D. Helton S. Dinsmore D. Naujock Date: December 1, 2008
K. Polson -2 The NRC staffs safety evaluation is enclosed. If you have any questions, please contact Richard Guzman, at (301) 415-1030.
Sincerely,
/raJ Mark G. Kowal, Chief Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-410
Enclosure:
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