ML15317A148

Request for Additional Information Email, Relief Request No. B-9 for Reactor Pressure Vessel Outlet Nozzle Safe End to Piping Welds, Second 10-year Inservice Inspection Interval

ML15317A148
Person / Time
Site:	Comanche Peak
Issue date:	11/13/2015
From:	Balwant Singal Plant Licensing Branch IV
To:	Hope T Luminant Generation Co
Singal B
References
CAC MF6553
Download: ML15317A148 (3)

Text

Burkhardt, Janet From: Singal, Balwant Sent: Friday, November 13, 2015 8:36 AM To: 'Hope, Timothy' (Timothy.Hope@luminant.com)

Cc: 'Jack.Hicks@luminant.com' (Jack.Hicks@luminant.com); Burkhardt, Janet

Subject:

Request for Additional Information (RAI) - Relief Request B-9 (CAC No. MF6553)

Attachments: RAI-MF6553-RR-B9.docx

Tim, By letter dated August 3, 2015 (Agencywide Documents Access and Management System (ADAMS)

Accession Number ML15224B362), Luminant Generation Company LLC requested relief from the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). Relief Request B-9 pertains to the examination coverage of the reactor pressure vessel (RPV) outlet nozzle safe end to stainless steel piping welds and RPV inlet nozzle safe end to elbow welds at the Comanche Peak Nuclear Power Plant, Unit 2.

The NRC staff requests for the attached additional information to complete the review of this RR.

Draft RAI were transmitted on November 6, 2015. Jack Hicks of your organization informed the NRC staff on November 12, 2015 that a clarification call is not needed.

Please treat this e-mail as formal transmittal of RAIs. You are requested to respond to this RAI request within 30 days from the date of this e-mail.

Thanks.

1

REQUEST FOR ADDITIONAL INFORMATION RELIEF REQUEST B-9 LUMINANT GENERATION COMPANY LLC COMANCHE PEAK NUCLEAR POWER PLANT, UNIT 2 DOCKET NUMBER 50-446 By letter dated August 3, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML15224B362), Luminant Generation Company LLC (the licensee) requested relief from the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). Relief Request B-9 pertains to the examination coverage of the reactor pressure vessel (RPV) outlet nozzle safe end to stainless steel piping welds and RPV inlet nozzle safe end to elbow welds at the Comanche Peak Nuclear Power Plant, Unit 2.

To complete its review, the U.S. Nuclear Regulatory Commission (NRC) staff requests the following additional information.

1. The NRC staff notes that for the ultrasonic testing (UT) personnel qualification and procedures demonstration, the licensee utilized the requirements in Supplements 2 and 10 of Appendix VIII to the ASME Code,Section XI. Please provide the edition and addenda of the ASME Code used for Appendix VIII.

2. Please provide the following information:

a. Material specifications (e.g., austenitic stainless steel pipes SA-376, TP-304 and austenitic stainless steel ER-308 weldment) for the welds and associated components (e.g., safe ends, pipes, and elbows).

b. Thickness of each pipe.

3. Please describe the following:

a. The inservice inspection history (i.e., inspection years, disposition of detected flaws, extent of condition assessment, and corrective actions).

b. Whether the licensee identified any indications during construction and preservice inspections (i.e., radiographic testing or surface examination, or both) on the volume not covered by UT.

c. Disposition of identified flaws.

4. Given the reduced inspection coverage of the welds under consideration, please discuss the following:

a. Any walkdowns (e.g., under Boric Acid Corrosion Control Program or normal operator rounds) usually performed to monitor and identify leakage in an unlikely event of a through wall leak.

Enclosure

b. Reactor coolant system leakage detection capabilities at the plant, or any measures taken, to monitor and identify leakage during operation in an unlikely event of a through wall leak in the welds under consideration.

5. In an unlikely event of a potential though wall flaw and leakage, please discuss significance of the leak and potential for structural failure of the subject weld.

6. Please discuss any industry or plant-specific operating experience regarding potential degradation (e.g., stress corrosion cracking and fatigue) and potential severe loading (e.g., vibration, water hammer, and overloading) for the subject weld and associated components.

7. Please discuss whether use of alternative volumetric examination techniques (e.g., the radiographic testing and phased array UT) would increase examination coverage.

8. Please clarify whether the UT covered the regions (i.e., the weld root and the heat affected zone of the base material near the inside diameter surface of the joint) that are typically susceptible to higher stresses and potential degradation.