ML090620146

Request for Additional Information Relief Request 13R-06, Alternatives to Requirements of ASME Code,Section XI for Class 1 Piping Welds Examined from Inside the Reactor Vessel

ML090620146
Person / Time
Site:	Wolf Creek
Issue date:	03/27/2009
From:	Balwant Singal Plant Licensing Branch IV
To:	Muench R Wolf Creek
Singal, Balwant, 415-3016, NRR/DORL/LPL4
References
TAC MD9658
Download: ML090620146 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 r1arch 27, 2009 Mr. Rick A. Muench President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, KS 66839

SUBJECT:

WOLF CREEK GENERATING STATION - REQUEST FOR ADDITIONAL INFORMATION RE: RELIEF REQUEST 13R-06, ALTERNATIVE TO THE EXAMINATION REQUIREMENTS OF ASME SECTION XI FOR CLASS 1 PIPING WELDS EXAMINED FROM THE INSIDE OF THE REACTOR VESSEL (TAC NO. MD9658)

Dear Mr. Muench:

By letter dated September 16, 2008 (Agencywide Document Access and Management System (ADAMS) Accession No. ML082670891), Wolf Creek Nuclear Operating Corporation (WCNOC) requested relief from certain American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI requirements. The licensee proposed an alternative to the depth sizing requirements of ASME Code Cases N-695, "Qualification Requirements for Dissimilar Metal Piping Welds," and N-696, "Qualification Requirements for Appendix VIII Piping Examinations Conducted From the Inside Surface," for the third 1O-year inservice inspection interval at Wolf Creek Generating Station.

Based on its review, the U.S. Nuclear Regulatory Commission (NRC) staff has determined that additional information is required to complete the evaluation for the above request for relief.

The NRC staff's request for additional information (RAI) is contained in the enclosure to this letter. These RAts were sent to Ms. Diane Hooper of WCNOC via e-mail on February 23, 2009 and discussed with WCNOC staff on March 5, 2009. Ms. Hooper agreed that WCNOC will provide its RAI response within 30 days from the date of issuance of this letter.

R. Muench -2 The NRC staff considers that timely responses to RAls help ensure sufficient time is available for the NRC staff to complete its review and contribute toward the NRC's goal of efficient and effective use of staff resources.

Sincerely, b~ \L0~~ i l b, ~~

Balwant K. Singal, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-482

Enclosure:

As stated cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION RELIEF REQUEST 13R-06 WOLF CREEK NUCLEAR OPERATING CORPORATION DOCKET NO. 50-482 By letter dated September 16, 2008 (Agencywide Document Access and Management System (ADAMS) Accession No. ML082670891), Wolf Creek Nuclear Operating Corporation (WCNOC) requested relief from certain American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI requirements. WCNOC proposed an alternative to the depth sizing error requirements of ASME Code Cases N-695, "Qualification Requirements for Dissimilar Metal Piping Welds," and N-696, "Qualification Requirements for Appendix VIII Piping Examinations Conducted From the Inside Surface," for the third 1O-year inservice inspection interval at Wolf Creek Generating Station (WCGS).

Since 2004, the Energy Power Research Institute - Performance Demonstration Initiative (PDI) representatives and U.S. Nuclear Regulatory Commission (NRC) staff have actively discussed the ASME Code requirements for depth sizing flaws in piping. At the December 2 and 3, 2008, public meeting with PDI and industry representatives, the NRC staff gave a presentation titled, "NRC Perspectives on Inside Diameter Pipe Examinations Depth Sizing Root Mean Square Error," (ADAMS Accession Nos. ML090760523 and ML090760528). The presentation identified potential issues with the current qualification test specimens and suggested that surface flatness issues as a possible hindrance in the qualification process. Securing the appropriate test specimens and acquiring appropriate qualifications may be impractical for WCNOC prior to the next refueling outage.

Based on its review of the WCNOC's submittal, the NRC staff has determined that the following additional information is required to complete an evaluation for impracticality.

Flaw Depth Sizing Alternative

1. Page 1 of the application identified welds as either Category B-F or Category B-J. Please provide representative sketches of the configurations and identify the weld and base material (carbon steel, stainless steel, Inconel, etc). Include in the sketches the impediments that are preventing the Code-required examinations.

2. Page 4 of the application indicates that these welds were examined during fourteenth refueling outage (RF14). If the vendor being used for the welds in this request is the same vendor that was used for RF14, please provide a discussion on the vendor's efforts to satisfy the Code-required root mean square error (RMSE) since RF14.

3. The Electric Power Research Institute (EPRI) - PDI identified a surface roughness criterion of 1/32-inch gap beneath the transducer for ultrasonic testing (UT) examinations. The inside diameter (ID) surface roughness of many of PDl's test specimens used for ID performance demonstrations are outside this standard. Having test specimens with an acceptable ID surface provides an

-2 opportunity for qualifying to the Code-required 0.125-inch RMSE. The availability of test specimens with acceptable ID surfaces is the responsibility of the entity desiring to use these test specimens in their performance demonstrations.

Please discuss the vendor's depth sizing RMSE capabilities when using test specimens made with acceptable ID surfaces.

4. The PDI program test specimens contain ID surface roughness that existed in the field prior to utilities implementing risk-informed inservice inspection (RI lSI) programs. These test specimens normally exceed the 1/32-inch gap between the transducer and surface that PDI determined as acceptable for UT examination. For RI lSI programs, the ID surfaces should be conducive to UT examinations. In the event that a flaw is detected, please discuss your efforts to provide a surface roughness that supports a vendor's 0.125-inch RMSE qualifications.

Flaw Detection Alternative During RF14, the NRC granted WCNDC a similar relief on these welds in a letter dated December 27,2006 (ADAMS Accession No. ML063470082). The relief was based on a partial UT examination combined with a supplemental eddy current testing examination and visual examination. In the WCNDC letter dated September 16, 2008, no visual examination is included in the proposed alternative. Please clarify if a visual examination is to be performed and, if not, please detail how the same level of safety will be accomplished.

Enclosure

• .. ML090620146 *Memo dated 2/20/09 OFFICE NRRlLPL4/PM NRRlLPL4/LA NRRlCPNB NRRlLPL4/BC NRR/LPL4/PM NAME BSingal JBurkhardt TChan' MMarkley BSingal DATE 3/9/09 3/9/09 2/20/09 3/26/09 3/27/09