ML13039A131

Request for Additional Information Related to Reactor Vessel Internals Inspection Plan Based on MRP-227-A (TAC Nos. ME9024, ME9025, and ME9026)

ML13039A131
Person / Time
Site:	Oconee
Issue date:	02/11/2013
From:	Boska J Plant Licensing Branch II
To:	Gillespie P Duke Energy Carolinas
Boska, J P
References
TAC ME9024, TAC ME9025, TAC ME9026
Download: ML13039A131 (7)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 February 11, 2013 Mr. Preston Gillespie Site Vice President Oconee Nuclear Station Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672-0752

SUBJECT:

OCONEE NUCLEAR STATION, UNITS 1,2, AND 3, REQUEST FOR ADDITIONAL INFORMATION RELATED TO REACTOR VESSEL INTERNALS INSPECTION PLAN BASED ON MRP-227-A (TAC NOS. ME9024, ME9025, AND ME9026)

Dear Mr. Gillespie:

By letter dated June 28, 2012, Duke Energy Carolinas, LLC submitted a license amendment request on the inspection plan for the reactor vessel internals (RVI) components at Oconee Nuclear Station (ONS), Units 1, 2, and 3 to the U.S. Nuclear Regulatory Commission (NRC) staff for review. This RVI inspection plan is based on MRP-227 -A, "Material Reliability Program:

Pressurized Water Reactor Internals Inspection and Evaluation Guidelines (MRP-227-A)," and supersedes the previous inspection plan submitted on November 8,2010.

The NRC staff is reviewing the submittal and has determined that additional information is needed to complete its review. The specific questions are found in the enclosed request for additional information (RAI). Please provide a response to these RAls within 45 days of the date of this letter.

If you have any questions, please call me at 301-415-2901.

Sincerely, o.~

~ hn P. Boska, Senior Project Manager lant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, and 50-287

Enclosure:

RAI cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION (RAn REGARDING REACTOR VESSEL INTERNALS INSPECTION PLAN DUKE ENERGY CAROLINAS. LLC OCONEE NUCLEAR STATION. UNITS 1, 2. AND 3 DOCKET NOS. 50-269. 50-270. AND 50-287 By letter dated June 28, 2012, Agencywide Documents Access and Management System Accession Nos. ML12187A214 and ML12187A215, Duke Energy Carolinas, LLC (Duke Energy) submitted an inspection plan for the reactor vessel internals (RVI) components at Oconee Nuclear Station (ONS), Units 1, 2, and 3 to the U.S. Nuclear Regulatory Commission (NRC) staff for review. This RVI inspection plan is based on MRP-227 -A, "Material Reliability Program:

Pressurized Water Reactor Internals Inspection and Evaluation Guidelines (MRP-227-A)," and supersedes the previous inspection plan submitted on November 8, 2010. The NRC staff is reviewing the submittal and has the following questions:

RAI-1

Topical Report Condition 7 of the NRC staff's safety evaluation (SE), Revision (Rev.) 1, dated December 16, 2011, on MRP-227-A, "Material Reliability Program: Pressurized Water Reactor Internals Inspection and Evaluation Guidelines (MRP-227-A)," states: "MRP-227, Appendix A shall be updated to include ... the Operating Experience Summary." Appendix A of MRP-227-A discussed operating experience under various degradation mechanisms for the reactor vessel internals (RVI) components of all nuclear steam supply system (NSSS) designs, including Babcock and Wilcox (B&W) plants. Please (1) identify the MRP-227-A, Appendix A experience which were contributed by the Oconee Nuclear Station (ONS), Units 1, 2, and 3 and (2) provide ONS experience on RVI degradations that were not discussed in Appendix A of MRP-227-A.

RAI-2

Historically, the following materials used in the pressurized water reactor (PWR) RVI components were known to be susceptible to some of the aging degradation mechanisms that are identified in MRP-227-A. In this context, the NRC staff requests that the licensee confirm that these materials are not currently used in the RVI components at ONS.

(1) Nickel base alloys -lnconeI600; Weld Metals - Alloy 82 and 182 and Alloy X-750 (2) Stainless steel type 347 material (excluding baffle-former bolts)

(3) Precipitation hardened (PH) stainless steel materials 4 and 15-5 (4) Type 431 stainless steel material

2 If one or more of these materials were used in the RVI components at ONS, provide information regarding their proposed inspections and basis to demonstrate that the proposed inspections are consistent with the intent of MRP-227-A

RAI-3

Section 4.1.3.1 of ANP-2951, Rev. 2, "Inspection Plan for the Oconee Nuclear Station Units 1, 2, and 3 Reactor Vessel Internals," in Attachment 1 of the June 28, 2012, submittal identified transient cycle count assumptions for the replacement bolting as a time-limited aging analysis (TLAA). Confirm whether the replacement bolts are the lower thermal shield (LTS) bolts.

Regardless of the confirmation, will the MRP-227-A specified examination method, frequency, and coverage for this RVI component item coexist with the management of this TLAA? Identify all RVI component items which have plant-specific measures (e.g., TLAAs) to supplement or replace the MRP-227-A inspections. Provide justification if deviation from MRP-227-A is identified for some of these RVI component items.

RAI-4

Section 4.1.3.2 of ANP-2951, Rev. 2 states: "Section 6.5 of this report describes the resolution to Applicant/Licensee Action Item 6 from the SER concerning the justification of acceptability of inaccessible components."

Applicant/Licensee Action Item 6 of the SE for MRP-227 -A requires the applicant provide justification for the continued operability of each of the inaccessible components and, if necessary, provide a plan for the replacement of the components for NRC review and approval. To ensure that Applicant/Licensee Action Item 6 requirements will be completed in time to support the Oconee inspection plan, the NRC staff will impose Condition 1 to this SE requiring the licensee provide information requested in Applicant/Licensee Action Item 6 of the SE for MRP-227 -A:

This amendment requires the licensee provide the detailed analysis, replacement schedule, or justification for some other alternative process for:

• the core barrel cylinder and welds,

• the former plates, and

• the bolting (core barrel-to-former bolts, internal and external baffle-to-baffle (88) bolts, and associated locking devices),

by the end of one year from the initial inspection of the Primary or linked Primary component items if the inspection results indicate aging, which is the Implementation Date for this condition. Any "other alternative process" shall include justification of operation in the degraded condition on a generic or plant-specific basis.

In response to RAI-4, the licensee needs to indicate that it has reviewed Condition 1 and agrees with the imposition of it to the SE for this license amendment request (LAR).

3

RAI-5

Section 4.1.3.2 of ANP-2951, Rev. 2 states, "Section 6.6 of this report describes the resolution to Applicant/Licensee Action Item 7 from the SER concerning plant-specific analyses to demonstrate RV Internals components fabricated from CASS, martensitic stainless steel, or precipitation-hardened stainless steel will maintain their functionality during the period of extended operation."

Commitment No.4 in Attachment 2 of the June 28, 2012, submittal specified the due date for addressing Action Item 7 as November 29, 2013. Instead of using the proposed Commitment No.

4, the NRC staff will impose Condition 2 to this SE requiring the licensee provide information requested in Applicant/Licensee Action Item 7 of the SE for MRP-227-A:

This amendment requires the licensee provide the plant-specific analyses to demonstrate that B&W IMI guide tube assembly spiders and CRGT spacer castings will maintain their functionality during the period of extended operation by November 29,2013, which is the Implementation Date for this condition. These analyses shall consider loss of fracture toughness due to thermal and irradiation embrittlement, and may also need to consider limitations on accessibility for inspection and the resolution/sensibility of the inspection techniques.

In response to RAI-5, the licensee needs to justify that the proposed date of November 29, 2013, is appropriate and to indicate that it has reviewed Condition 2 and agrees with the imposition of it to the SE for this LAR.

RAI-6

Section 4.1.6 of ANP-2951, Rev. 2 states that, "The "Primary" requirement from MRP-227-A for a one-time physical measurement of the interference fit between the plenum cover weldment rib pads and the RV flange was performed at ONS between 2006 and 2008 in order to provide data to the investigation." Discuss the impact of these measurements on the MRP-227-A specified subsequent visual (VT-3) examination on the 10-year inservice inspection (lSI) interval for ONS, Units 1, 2, and 3.

RAI-7

Section 4.2 of ANP-2951, Rev. 2 states that, "visual examination of baffle-to-baffle and baffle-to-former bolts at each RFO [refueling outage]." Confirm that Duke Energy will perform ultrasonic testing (UT) examinations for baffle-to-baffle and baffle-to-former bolts in accordance with Examination Method/Frequency of MRP-227 -A, and the stated visual examinations simply supplement the UT examinations. Justify if this is not the case.

RAI-8

Table 4-2 of ANP-2951, Rev. 2 defined "typical" ONS core support structure components for Examination Category B-N-3 of the American Society of Mechanical Engineers Boiler & Pressure Vessel Code (ASME Code),Section XI. Describe the process and effort in making Table 4-2 to ensure that Table 4-2 did not miss any important core support structure components. Identify the

4 ONS core support structure components which were inspected as B-N-3 Examination Category in the past but are not included in Table 4-2 and provide justification, including past inspection results, for their exclusion.

RAI-9

Section 4.2.5 of ANP-2951, Rev. 2 states that, "Failure of the original Alloy A-286 LTS bolts in the 1980s led to the replacement of all the original LTS bolts with replacement studs/nuts at the three ONS units." The replacement studs/nuts are made from Alloy X-750 in the high temperature heat-treatment condition. Discuss the inspection results accumulated in the past 30 years at the three ONS units for the replacement LTS bolts to demonstrate that this operating experience supports the MRP-227 -A specified examination method/frequency/coverage for this RVI component item.

RAI-10

Section 4.2.6 of ANP-2951, Rev. 2 states that, "The Alloy X-750 dowels, Type 304 screws, and their locking welds [related to plenum cover ribs for ONS, Unit 1 only] were unknown and were not screened for aging degradation mechanisms, nor evaluated for inclusion in MRP-227." Confirm that this RVI component item is within the scope of the LR in accordance with 10 CFR 54.4 and will be included in your response to address Applicant/Licensee Action Item 2 of the SE for MRP-227-A regarding whether Tables 4-1 and 4-2 in MRP-189, Rev. 1 and Tables 4-4 and 4-5 in MRP-191 have missed any RVI component items that should be within the scope of the LR.

RAI-11

Section 4.2.7 of ANP-2951, Rev. 2 states that, "UT examinations for the LCB [lower core barrel]

bolts are planned during the RV Internals inspections in 2012,2013, and 2014, in compliance with the MRP-227-A examinations requirement for the LCB bolts." Provide similar information on examinations of all kinds (i.e., visual or UT) for all other RVI component items to be performed before the end of the current 40-year license in compliance with the MRP-227 -A examinations requirement.

RAI-12

Section 5.1.1 of ANP-2951, Rev. 2 states that, "See Section 2.4 of this report for a discussion of the scope of the components considered for inspection for the program to manage the aging of the ONS RV Internals." The NRC staff reviewed Section 2.4 and did notfind a clear definition of the scope of the components. Hence, the NRC staff requested the licensee confirm that the ONS RVI inspection plan includes all RVI component items listed in Tables 4-1 (Primary) and 4-4 (Expansion) of MRP-227-A and those listed in Table 4-2 (Existing) of ANP-2951, Rev. 2. If it is not confirmed, demonstrate that the ONS RVI inspection plan is still appropriate.

RAI-13

Section 6.3 of ANP-2951, Rev. 2 discussed Applicant/Licensee Action Item 2 of the SE for MRP-227-A regarding whether Tables 4-1 and 4-2 in MRP-189, Rev. 1 and Tables 4-4 and 4-5 in MRP-191 have missed any RVI components that should be within the scope of the LR to support

5 the current review. Commitment No.1 in Attachment 2 of the June 28,2012, submittal specified the due date for addressing Action Item 2 as May 31,2013. Please provide this information in response to this RAI, as the NRC staff needs it in order to make a decision on this license amendment.

RAI-14

Section 6.4 of ANP-2951, Rev. 2 discussed Applicant/Licensee Action Item 4 of the SE for MRP-227-A regarding whether the core support structure upper flange weld was stress relieved during the original fabrication of the RV in order to determine whether this RVI component item should be revised from Expansion Category to Primary Category. Commitment No.2 specified the due date for addressing Action Item 4 as February 29, 2013. Please provide this information in response to this RAI, as the NRC staff needs it in order to make a decision on this license amendment.

RAI-15

Section 2.5 of Appendix 0 of ANP-2951, Rev. 2 indicated that an operability assessment considering UT results and future LCB bolt failure was performed for Arkansas Nuclear One, Unit 1 (ANO-1). This section also revealed the technical elements addressed in this ANO-1 operability assessment. Confirm that if relevant conditions have been identified in the UCB or LCB bolts at any of the ONS units, an operability evaluation required by WCAP-17096, Rev. 2 will be performed consistent with the ANO-1 operability assessment and provided to NRC for review. To support evaluation of this potential future operability assessment, Reference 14 regarding minimum number of bolts required for operation shall also be provided at that time.

ML13039A131 *See memo OFFICE NRR/lPl2*1IPM NRRllPl2-lILA NRR/EVIB/BC* NRR/lPl2-1/BC NRR/lPl2-lIPM NAME JBoska SFigueroa SRosenberg RPascarelli JBoska DATE 2/11/13 2/11/13q 11/1/12 2111113 2/11113