ML17107A319

Aluminum Bronze Selective Leaching Aging Management Program Audit Report Regarding the South Texas Project, Units 1 and 2, License Renewal Application (CAC Nos. ME4936 and ME4937)

ML17107A319
Person / Time
Site:	South Texas
Issue date:	05/16/2017
From:	Lois James Division of License Renewal
To:	Gerry Powell South Texas
Lois James, NRR/DLR, 4153306
References
CAC ME4936, CAC ME4937
Download: ML17107A319 (8)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 16, 2017 Mr. G.T. Powell Site Vice President STP Nuclear Operating Company P.O. Box 289 Wadsworth, TX 77483

SUBJECT:

SELECTIVE LEACHING OF ALUMINUM BRONZE AGING MANAGEMENT PROGRAM AUDIT REPORT REGARDING THE SOUTH TEXAS PROJECT, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION (CAC NOS. ME4936 AND ME4937)

Dear Mr. Powell:

By letter dated October 25, 2010, STP Nuclear Operating Company (or the applicant) submitted an application for renewal of operating licenses NPF-76 and NPF-80 for the South Texas Project (STP), Units 1 and 2. By letter dated January 24, 2017, the staff of the U.S. Nuclear Regulatory Commission (NRC or the staff) issued an audit plan (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17017A148) to inform you of our intent to conduct an in-office follow-up regulatory audit of your Selective Leaching of Aluminum Bronze Aging Management Program (AMP) and associated issues. By letter dated March 23, 2017, the staff amended the audit plan to extend the audit closure date from March 3, 2017, to April 28, 2017 to permit continued review of the Selective Leaching of Aluminum Bronze AMP (ADAMS Accession No. ML17068A253).

During the audit period, a question arose concerning STPs bolting integrity AMP, specifically regarding closure bolting located in air-filled, gas-filled, or air-filled systems that are not normally pressurized. The staff is also documenting its review of documents relevant to the bolting integrity AMP.

The NRC staff has completed its audit activities and documented the results in the enclosed audit report.

G.T. Powell If you have any questions, please contact me by telephone at 301-415-3306 or by e-mail at Lois.James@nrc.gov.

Sincerely,

/RA/

Lois M. James, Senior Project Manager Project Management and Guidance Branch Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-498 and 50-499

Enclosure:

As stated cc: Listserv

ML17107A319 OFFICE LA:RPGB:DLR PM: RPGB:DLR BC:RARB:DLR BC:RPGB:DLR NAME YEdmonds LJames DMorey SBloom DATE 5/11/2017 5/15/2017 4/25/2017 5/16/2017 OFFICE PM:RPB1:DLR NAME LJames DATE 5/16/2017

AUDIT REPORT FOR SOUTH TEXAS PROJECT, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION REVIEW SELECTIVE LEACHING OF ALUMINUM BRONZE AGING MANAGEMENT PROGAM (CAC NOS. ME4936 AND ME4937)

Docket Nos: 50-498 and 50-499 License Nos: NPF-76 and NPF-80 Licensee: STP Nuclear Operating Company Facility: South Texas Project, Units 1 and 2 Location: P.O. Box 289 Wadsworth, TX 77483 Dates: January 20 - April 18, 2017 Reviewers: Stephen Cumblidge, Materials Engineer Component Performance, NDE, and Testing Branch Division of Engineering Office of Nuclear Reactor Regulations William Holston, Senior Mechanical Engineer Aging Management of Reactor and Mechanical System Branch Division of License Renewal Office of Nuclear Reactor Regulations Lois James, Senior Project Manager Project Management and Guidance Branch Division of License Renewal Office of Nuclear Reactor Regulations Carol Nove, Senior Materials Engineer Component Integrity Branch Division of Engineering Office of Nuclear Regulatory Research Approved By: Dennis Morey, Chief Aging Management of Reactor and Mechanical System Branch Division of License Renewal Office of Nuclear Regulatory Research ENCLOSURE

1.0 INTRODUCTION

By letter dated October 25, 2010, STP Nuclear Operating Company (STPNOC or applicant) submitted an application pursuant to Title 10 of the Code of Federal Regulations Part 54, to renew the operating license NPF-76 and NPF-80 for South Texas Project (STP), Units 1 and 2, for review by the U.S. Nuclear Regulatory Commission (NRC or the staff).

Between January 20 and April 18, 2017, the NRC staff conducted an in-office audit to examine STPNOC Selective Leaching of Aluminum Bronze aging management program (AMP) and related documents.

The purpose of the audit was to gain an understanding of the applicants AMP for aluminum bronze welds that are susceptible to loss of material due to selective leaching such that the NRC staff has confidence that Open Item 3.0.3.3.3-2 in the 2016 Safety Evaluation Report with Open Items (Agencywide Documents and Access Management System (ADAMS) Package Accession No. ML16271A011) has a closure path. This audit focused on the "corrective actions" program element of the Aluminum Bronze Selective Leaching AMP, specifically the Time-of-Flight Diffraction (TOFD) ultrasonic testing (UT) technique for examining aluminum bronze welds.

During the audit period, a question arose concerning STPs bolting integrity AMP. The NRC staff examined plant-specific documents related to managing the aging effects for closure bolting located in air-filled or gas-filled systems, or air-filled systems that are not normally pressurized.

In performing the audit, the NRC staff examined the applicants license renewal application (LRA), supplements to the LRA, program-bases documents and related references, and interviewed various applicant representatives.

Results of this audit will be ultimately documented in the NRC staffs safety evaluation report (SER). The table below lists the documents that were reviewed by the NRC staff and found relevant to the audit.

Relevant Documents Reviewed Document Title Revision/Date LRA Section A1.37 Selective Leaching of Aluminum Bronze NA UFSAR Supplement LRA Section B2.1.37 Selective Leaching of Aluminum Bronze NA AMP UTI-TOFD-AB-002 Ultrasonic Technical Instruction: Revision 1 Ultrasonic Examination of Aluminum Bronze Piping Butt Welds for Selective Leaching Using the Time-of-Flight Diffraction (TOFD) Technique NDE-PQ-2017-002 Ultrasonic Examination of Aluminum Revision 1 UTI-TOFD-AB-002 Bronze Pipe to Pipe Butt Welds for Selective Leaching Using the Time-of-Flight Diffraction (TOFD)

Technique

Relevant Documents Reviewed Document Title Revision/Date SEG-0001 System Engineer Administrative Revision 15 Guidance 0PGP03-ZA-0133 Fluid Leak Management Program Revision 4 2.0 PLANT-SPECIFIC PROGRAMS 2.1 Selective Leaching of Aluminum Bronze Aging Management Program During the audit of the Selective Leaching of Aluminum Bronze Aging Management Program, the staff interviewed the applicants staff and reviewed documentation provided by the applicant.

The staff reviewed LRA changes associated with dealloying of aluminum-bronze welds along with a Technical Justification Report and a plant-specific nondestructive examination (NDE) procedure associated with TOFD UT examinations. The staff made the following observations based on the content of the reports.

• The staff reviewed changes to LRA Sections A1.37 and B2.1.37 and conducted breakout sessions with the applicant. During these breakout sessions, the staff discussed degraded but operable criteria for welds that did not meet structural integrity requirements, the extent of TOFD UT examinations, and evaluation criteria for potential follow-on inspections of buried pipe welds. Near the end of the audit, the applicant submitted changes to the LRA by letter dated March 30, 2017. The staffs evaluation of the final version of the AMP and Updated Final Safety Analysis Report (UFSAR)

Supplement is documented in the SER.

• The staff reviewed the Technical Justification for the TOFD UT examination technique and the plant-specific procedure for implementing the TOFD UT examination technique.

During breakout sessions with the applicant, the staff discussed specific concerns with the documents encompassed within the following six areas: (a) qualifications; (b) scanning; (c) calibration; (d) detection; (e) sizing; and (f) noise. Subsequent to review of the final documents, the staff noted that:

o Personnel are qualified in accordance with the plant-specific NDE written practices document and will have: (a) completed 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br /> of TOFD class; (b) demonstrated detection and sizing capability; and (c) met all aspects of a Practical Examination 10 Point Checklist.

o The procedure requires the weld crown preparation to be conditioned to a smooth flat (in-service inspection finish) and scanning is conducted in a direction parallel to the weld.

o The encoder is calibrated such that the display of measured distance is within one percent of actual distance moved.

o The procedure states that when dealloying approaches the outside diameter surface, the lateral wave may break or have a localized reduction in its strength coupled with changes in the back wall thickness.

o The procedure states that the depth of dealloying is determined by selection of the deepest TOFD arc reflector, and dealloying length is derived from the overall presence of the TOFD arcs and measured down to the noise level.

o The procedure addresses determining the source of excessive noise by signal averaging.

In addition to identifying the above concerns that were resolved by the applicant with revisions to the documents prior to completion of the audit, the staff noted:

• The use of the method was validated by conducting TOFD UT examinations followed by destructive examination to confirm that the extent of degradation had been sufficiently detected by the examination technique.

• The applicants plant-specific procedures include: (a) qualification requirements for examiners that collect the data and examiners that interpret the data; (b) the equipment to be used for the inspections; (c) essential variables for the inspections; (d) details on how to conduct the inspections; and (e) requirements for data analysis and recording.

• A technical justification was provided, which meets a Low Rigor level of qualification conducted in accordance with the 2004 Edition of ASME Code Section V, Nondestructive Examination, Article 14, Examination System Qualification.

2.2 Managing Aging Effects for Closure Bolting Located in Air-Filled, Gas-Filled, or Air-Filled Systems that are not Normally Pressurized During this audit the NRC staff interviewed the applicants staff and reviewed documentation provided by the applicant.

The staff reviewed procedures SEG-001 and 0PGP03-ZA-0133 to determine whether the plant-specific procedures included adequate controls to manage loss of material due to general (where applicable), pitting. or crevice corrosion, cracking due to stress corrosion cracking, or loss of preload due to thermal effects, gasket creep, and self-loosening for air-filled or gas-filled systems, or air-filled systems that are not normally pressurized. The staff noted that:

• SEG-001 states that for valves, inspections for leakage are conducted at connections, and particularly for air-operated values leaks at hoses and regulators. The Appendix also states that for instrument/electrical connections inspections occur for air or fluid leaks. The procedure cites 0PGP03-ZA-0133.

• 0PGP03-ZA-0133 cites criteria for leaks evidenced by the use of leak detection fluid; however, it does not state that every air-filled or gas-filled bolted connection is subject to leak detection fluid testing. Addendum 1 Leakage Classification Severity, states, Gas leakage stream detectable by motion of a tell-tale as a severity level C; however, again there is no requirement to use a tell-tale at all air-filled or gas-filled bolted connections.

• The definition for a fluid, as cited in SEG-001, includes compressed gas systems, but not those at atmospheric pressure. It is possible that there are in-scope air-filled systems that are not normally pressurized.

Based on the available information, the staff concluded that the applicants plant-specific procedures do not include adequate guidance to detect loss of preload or loss of material for closure bolting associated with air-filled or gas-filled systems, or air-filled systems that are not normally pressurized. The staff will review future submittals in regard to this topic and document its evaluation in SER Section 3.0.3.2.5.

3.0 EXIT MEETING At the conclusion of the audit, an exit meeting was held on April 18, 2017, to summarize the review completed. No follow-up requests for additional information will be issued.

4.0 LIST LICENSEE STAFF THAT PARTICIPATED IN THE AUDIT Name Title Affiliation Mike Murray Manager of Regulatory Affairs STP Lance Sterling Supervisor of Regulatory Affairs STP Arden Aldridge Supervisor of Engineering Projects STP Rob Engen Manager of Engineering Projects STP Craig Younger Testing and Programs Supervisor STP Lyle Spiess Testing and Programs Supervisor STP Rafael Gonzales Licensing Staff Engineer STP Gary Warner License Renewal Support Worley Parsons Mike Garner Testing and Programs - STP Consulting Engineer