ML14183B719

Requests for Additional Information for the Review of the South Texas Project, Units 1 and 2, License Renewal Application Set 28

ML14183B719
Person / Time
Site:	South Texas
Issue date:	07/16/2014
From:	Daily J License Renewal Projects Branch 1
To:	Koehl D South Texas
Daily J, 415-3873
References
TAC ME4936, TAC ME4937
Download: ML14183B719 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 16, 2014 Mr. Dennis L. Koehl President and Chief Nuclear Officer STP Nuclear Operating Company P.O. Box 289 Wadsworth, TX 77483

SUBJECT:

REQUESTS FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE SOUTH TEXAS PROJECT, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION - SET 28 (TAC NOS. ME4936 AND ME4937)

Dear Mr. Koehl:

By letter dated October 25, 2010, STP Nuclear Operating Company submitted an application pursuant to Title 10 of the Code of Federal Regulations Part 54, to renew operating licenses NPF-76 and NPF-80 for South Texas Project, Units 1 and 2, for review by the U.S. Nuclear Regulatory Commission (NRC) staff. The NRC staff is reviewing the information contained in the license renewal application and has identified, in the enclosure, areas where additional information is needed to complete the review.

This request for additional information has been presented to Mr. Arden Aldridge of your staff, and we request your response within 90 days of the date of this letter. If portions of your response need more time, please advise the staff of the date that information will be provided.

If you have any questions, please contact me by telephone at 301-415-3873 or by e-mail at john.daily@nrc.gov.

Sincerely,

/RA/

John W. Daily, Sr. Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-498 and 50-499

Enclosure:

As stated cc w/encl: Listserv

ML14183B719

• concurrence via email OFFICE PM: DLR/RPB1 LA: DLR/RPB1 BC: DLR/RPB1 PM: DLR/RPB1 NAME JDaily YEdmonds YDiaz JDaily DATE 7/14/14 79/14 7/16/14 7/16/14

ENCLOSURE SOUTH TEXAS PROJECT, UNITS 1 AND 2 REQUEST FOR ADDITIONAL INFORMATION - SET 28 (TAC NOS. ME4936 AND ME4937)

RAI B2.1.35 Aging Management of Reactor Vessel Internals and MRP-227A

Background:

The license renewal application (LRA) for South Texas Project (STP), Units 1 and 2, proposed aging management for the reactor vessel internal (RVI) components based on a regulatory commitment in the LRAs Updated Final Safety Analysis Report (UFSAR) Supplement. The commitment stated that the applicant will develop an aging management program (AMP) and inspection plan based on augmented inspection activities for the components developed by the EPRI Materials Reliability Project (MRP), and that the inspection plan will be submitted for NRC review and approval at least two (2) years prior to entering into the period of extended operation for STP, Units 1 and 2.

The NRCs recommended AMP for Pressured Water Reactor (PWR) RVIs in Revision 2 of NUREG-1801, Generic Aging Lessons Learned (GALL) Report, is given in Section XI.M16A, PWR Vessel Internals, which was issued in December 2010. On January 9, 2012, subsequent to the issuance of Revision 2 of the GALL Report, the EPRI MRP issued Technical Report No.

1022863, Materials Reliability Program: Pressurized Water Reactor Internals Inspection and Evaluation Guidelines (MRP-227-A), which included the NRC safety evaluation (SE) on the reports methodology dated December 16, 2011. On June 3, 2013, the staff revised AMP XI.M16A and the aging management review (AMR) items in the GALL Report for PWR RVI components to be consistent with the contents of the MRP-227-A report and issued them in License Renewal Interim Staff Guidance Document No. LR-ISG-2011-04, Updated Aging Management Criteria for Reactor Vessel Internal Components of Pressurized Water Reactors.

On July 21, 2011, the NRC issued Regulatory Information Summary (RIS) 2011-07, License Renewal Submittal Information for Pressurized Water Reactor Internals Aging Management, which provided updated NRC procedures for LRA reviews of PWR RVI AMPs. This RIS identifies Category C plants as those plants that have an LRA currently under review, and states that these applicants will be expected to revise their commitment for aging management of PWR vessel internals such that the information identified in the SE for MRP-227 would be submitted to the NRC for review and approval not later than two years after issuance of the renewed license or not later than two years before the plant enters the period of extended operation, whichever comes first. STP, Units 1 and 2, are Category C plants in accordance with the RIS.

Issue:

The categorization of STP, Units 1 and 2, and other plants in Category C of RIS 2011-07 was based on an expectation that the LRA would be reviewed and approved on a normal review schedule of 22 months, and that it would be an unreasonable burden to expect the applicant to address all aspects of the NRCs SE for MRP-227 within the LRA review. However, the applicant requested that the NRC place the LRA review on hold for the year 2013 to allow the applicant to address plant-specific technical issues. The staff noted that, as of the date of this RAI, the review of these technical issues is still on-going. Since the resolution of these issues is not imminent and completion of the staffs review of the LRA is on-going, the staff has concluded that the applicant should provide an LRA update or amendment that includes updated AMP and AMR items for the RVI components, including responses to the applicable Applicant/License Actions Items identified in the staffs SE for MRP-227.

In addition to the issues identified above, the staff has noted that recent operating experience at one 4-loop PWR (in 2010) reported cracking and failures of some nickel alloy (Alloy X-750) clevis insert bolts in the clevis assemblies attached to the lower internal portion of its reactor vessel (see EPRI Technical Report No. 1022863, Materials Reliability Program: Pressurized Water Reactor (PWR) Internals Inspection and Evaluation Guidelines (MRP-227-A), Appendix A). The staff further noted that some inspection routines (such as an ASME Section XI visual VT-3 inspection on a 10-year frequency) of the clevis insert assemblies may not be adequate to ensure the integrity of clevis insert assemblies during design basis events if multiple bolt failures occur prior to detection, and then the design basis event were to occur.

Request:

The staff requests that STPNOC provide the following:

1. MRP-227-A Applicant/Licensee Action Items (A/LAIs): Provide either an LRA amendment or update that includes an updated AMP, updated AMR items, and any applicable inspection plan(s) for the PWR RVI components at STP, Units 1 and 2, that are based on the guidance in LR-ISG-2011-04, including responses to applicable A/LAIs identified in the staffs SE for MRP-227, dated December 16, 2011.

2. Reactor vessel clevis assemblies: Please address the clevis insert bolt operating experience issue cited above in reference to STP:

a) Describe the configuration of clevis insert assemblies at STP, including number of bolts in the assemblies. Specify the materials of fabrication, including any applicable heat treatments, that were used for the design of the clevis insert bolts at STP.

b) Discuss and justify whether the operating experience associated with cracking of the clevis insert bolts is applicable to the clevis insert assembly designs at STP.

c) Describe the inspections that have been performed of the clevis insert bolts, including the type of inspection (e.g., VT-3). Discuss the visual inspection coverage that was achieved during these inspections. Clarify the ASME examination category that applies to inspections of the clevis insert bolts (and identify the applicable inspection method and frequency) and whether any past examinations have resulted in the detection of any indications of cracking or failures of the clevis insert bolts that are included in the clevis insert assembly designs. If so, provide the details of the inspection results and clarify the corrective actions that were taken at the facility to justify the structural integrity of the clevis insert assemblies and the intended safety function of the plant's core support structure and its components during plant operations.

d) Based on your responses to Parts (a) through (c) of this request, clarify whether the 10-year lSI basis (or the current approach used for STP) for the clevis insert bolts is sufficient to manage cracking and wear of the bolts during the period of extended operation. Justify your response to this request.

Letter to D. L. Koehl from John W. Daily dated July 16, 2014

SUBJECT:

REQUESTS FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE SOUTH TEXAS PROJECT, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION - SET 28 (TAC NOS. ME4936 AND ME4937)

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