ML12117A191
| ML12117A191 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 05/02/2012 |
| From: | Patrick Boyle Plant Licensing Branch II |
| To: | Ajluni M Southern Nuclear Operating Co |
| Boyle P | |
| References | |
| TAC ME8315, TAC ME8316 | |
| Download: ML12117A191 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 2,2012 Mr. M. J. Ajluni Nuclear Licensing Director Southern Nuclear Operating Company, Inc.
40 Inverness Center Parkway P.O. Box 1295 Bin - 038 Birmingham, Alabama 35201-1295
SUBJECT:
VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING THE PROPOSED INSERVICE INSPECTION ALTERNATIVE VEGP-ISI-ALT-07 (TAC NOS. ME8315AND ME8316)
Dear Mr. Ajluni:
By letter dated March 23, 2012 (Agencywide Documents Access and Management System, Accession No. ML12086A106). Southern Nuclear Operating Company. Inc. (the licensee),
submitted a request for alternative for Inservice Inspection Program. Responses to the enclosed Request for Additional Information are needed for us to continue our review.
Please provide a response within thirty (30) calendar days of the date of this letter.
Sincerely, Patrick G. Boyle, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-424 and 50-425
Enclosure:
Request for Additional Information cc wi encl: Distribution via Listserv
REQUEST FOR ADDITIONAL INFORMATION INSERVICE INSPECTION ALTERNATIVE VEGP-ISI-ALT-07 VERSION 1.0 VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 DOCKET NOS. 50-424 AND 50-425 TAC NOS. ME8315 AND ME8316 By letter dated March 23, 2012, (Agencywide Document Access and Management System (ADAMS) Accession No. ML12086A106), Southern Nuclear Operating Company, Inc. (the licensee), submitted an inservice inspection (lSI) alternative request VEGP-ISI-ALT-07, Version 1.0 for the U.S. Nuclear Regulatory Commission (NRC) review and approval. The alternative is related to the inspection of the reactor vessel head penetrations at Vogtle Electric Generating Plant, Units 1 and 2 that is required pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Section 50.55a(g)(6)(ii)(D). To complete the review, the NRC requests the following additional information:
- 1.
The licensee referenced Figure 2 in American Society of Mechanical Engineers (ASME)
Code Case N-729-1 for the examination of the reactor vessel head nozzle penetrations.
It appears that the penetration at Vogtle is slightly different from Figure 2 of N-729-1 in that the lower region of the Vogtle penetration nozzle is threaded. Figure 2 of the ASME Code Case N-729-1 uses alphabetic letters to identify specific areas/regions of interest for the J-groove weld and nozzle. The relief request (RR) discussed the following areas/regions of interest: the bottom of the fillet, the toe of the J-groove weld, chamfered regions, regions having a radius, the distance between the lowest point at the toe of the J-groove weld and the bottom of the scanned region, the proposed alternative examination zone, incidence angle, thread sections, thread relief, and shadow zone in the threaded region. It is not clear to the staff how these terms relate to the "lettered" dimensions in Figure 2 of ASME Code Case N-729-1, address the following: (a) Please provide a drawing(s) of a typical control rod drive mechanism penetration nozzle showing the threaded region with a tapered inside surface at the bottom of the control rod drive mechanism (CRDM) nozzle; and (b) in the drawing, please identify the items that correspond to the letters used in Code Case N-729-1 and to the areas/regions mentioned in the RR.
- 2.
It is not clear to the staff under which regulation is the RR submitted. Paragraph 10 CFR 50.55a(a)(3) states, in part, that alternatives to the requirements of 10 CFR 50.55a(g) may be used, when authorized by the NRC, if the licensee demonstrates (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. It is staff's expectation that for the control rod drive mechanism nozzle configuration including J-groove weld, 10 CFR 50.55a(a)(3)(ii) would be the appropriate regulation to be used for the RR. Additionally, the authorization per 10 CFR 50.55a(a)(3) is required ENCLOSURE
~2-by 10 CFR 50.55a(g)(6)(D)(6). Confirm that the RR is submitted under 10 CFR 50.55a(a)(3)(ii).
- 3.
Tables 1 and 2 of the RR provide the previous inspection coverage length obtained for CRDM in units 1 and 2, respectively, address the following: (a) Explain why there are more nozzles in Unit 1 that could not achieve the required coverage than in Unit 2. Also explain why the nozzles in unit 1 that could not achieve the required coverage but the same nozzles in unit 2 were able to achieve the required coverage, assuming the nozzle penetration configurations between two units are identical; and (b) in Table 1, Nozzle Numbers 2 and 5 have an actual coverage length of 1.52 inches from the previous examination. The required length is 1.5 inches. The small difference of 0.02 inches between the actual and required coverage length provides a very small margin between the acceptable coverage and coverage for which relie'f is required. Discuss the accuracy (or tolerance) of the measured lengths in Tables 1 and 2. Discuss whether the coverage length recorded in Tables 1 and 2 includes any measurement uncertainty. Discuss whether Nozzle Nos. 2 and 5 and other similar nozzles should be included in Table 3 of the RR as nozzles that require relieffrom 10 CFR 50.55a(g)(6)(ii)(D).
- 4.
Section 1 of the RR states that affected components are UNS N06600 nozzles and UNS N06082 or UNS W86182 partial penetration welds in reactor vessel head in units 1 and
- 2. Table 3 of the RR lists the nozzles that require relief from the volumetric and surface examinations of Code Case N~729~1. It is staff's expectation that only those nozzles that require relief need to be referenced in the RR. Discuss whether the RR is applicable to only those nozzles that are stated in Section 1 of the RR or cited in Table 3.
- 5.
Section 5.2, 3rd paragraph, of the RR states that the flaw tolerance chart in Figures 5 through 8 demonstrates that a postulated through-wall flaw at the bottom edge of the proposed alternative examination zone will not grow to the toe of the J~roove weld, address the following: (a) identify the alternative examination zone in the drawing that the staff has requested above; (b) provide the as-designed (Le., as~analyzed) and as built dimensions of the J-groove weld; and (c) discuss whether the flaw evaluation in WCAP-16493-P, Revision 0 is based on the as-designed or as-built J~roove weld dimensions. If the flaw evaluation was based on the as-designed dimensions, demonstrate that it bounds the flaw evaluation of the as-built dimensions.
- 6.
In Section 5.1 of the RR, the licensee stated that it recently reviewed WCAP-16493-P and confirmed the report's continued applicability. Discuss how the review and confirmation was conducted. For example, discuss the parameters that were reviewed to confirm the continued applicability. Alternatively, the licensee may submit Reference number 9 in Section 8 of the RR which is the Letter from Westinghouse to the licensee dated January 31, 2012.
May 2,2012 Mr. M. J. Ajluni Nuclear Licensing Director Southern Nuclear Operating Company, Inc.
40 Inverness Center Parkway P.O. Box 1295 Bin -038 Birmingham, Alabama 35201-1295
SUBJECT:
VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING THE PROPOSED INSERVICE INSPECTION ALTERNATIVE VEGP-ISI-ALT-07 (TAC NOS. ME8315AND ME8316)
Dear Mr. Ajluni:
By letter dated March 23, 2012 (Agencywide Documents Access and Management System, Accession No. ML12086A106), Southern Nuclear Operating Company, Inc. (the licensee),
submitted a request for alternative for Inservice Inspection Program. Responses to the enclosed Request for Additional Information are needed for us to continue our review.
Please provide a response within thirty (30) calendar days of the date of this letter.
Sincerely, IRA!
Patrick G. Boyle, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-424 and 50-425
Enclosure:
Request for Additional Information cc wI encl: Distribution via Listserv DISTRIBUTION:
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- via e-mail OFFICE N RRlLPL2-1/PM NRRlLPL2-1/LA NRRlEPNBlBC*
NRRlLPL2-1/BC NRRlLPL2-1/PM Ii NAME PBoyle SFigueroa TLupold NSalgado PBoyle (DAiley for)
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- DATE 04/30/12 04/26/12 04/17/12 05/02/12 05/02112 II OFFICIAL RECORD COpy