L-MT-06-020, Clarification to 10 CFR 50.55a Request No. 13: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year Inservice Inspection Interval

Clarification to 10 CFR 50.55a Request No. 13: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year Inservice Inspection Interval

ML061420153
Person / Time
Site:	Monticello
Issue date:	05/17/2006
From:	Conway J Nuclear Management Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-MT-06-020
Download: ML061420153 (2)

Text

Km Monticello Nuclear Generating Plant NMC Committed to NuclearYExceIle Operated by Nuclear Management Company, LLC May 17, 2006 L-MT-06-020 10 CFR 50.55a(g)(5)(iii)

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Monticello Nuclear Generating Plant Docket 50-263 License No. DPR-22 Clarification to 10 CFR 50.55a Request No. 13: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(q)(5)(iii) for the Fourth Ten-Year Inservice Inspection Interval

Reference:

1) NMC to NRC letter, "10 CFR 50.55a Request No. 13: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year Inservice Inspection Interval,"

(L-MT-05-088) dated September 27, 2005.

On September 27, 2005, the Nuclear Management Company, LLC (NMC) submitted a 10 CFR 50.55a request for relief (Reference 1) for certain weld examinations where the coverage required for inservice inspection by Section Xl of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code could not be obtained. These examinations were performed during the 2005 refueling outage for the Monticello Nuclear Generating Plant (MNGP).

In response to informal discussions with the NRC staff, this supplement clarifies that relief is not being requested for those areas where coverage is demonstrated by use of the MNGP specific Electric Power Research Institute computer modeling report (Enclosure 1, Reference 1).

This letter contains no new commitments and makes no revisions to existing commitments.

gn . Conway )

Site Vice President, Montic uclear Generating Plant Nuclear Management Company, LLC Enclosure (1) cc: Administrator, Region l1l, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC Minnesota Department of Commerce (Attn: L. Brandon) A LV7 2807 West County Road 75

• Monticello, Minnesota 55362-9637 Telephone: 763.295.5151

• Fax: 763.295.1454

as - -

ENCLOSURE 1 SUPPLEMENT TO 10 CFR 50.55a REQUEST NO. 13 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY The Nondestructive Examination (NDE) procedures used at the Monticello Nuclear Generating Plant (MNGP) incorporate examination techniques qualified under Appendix Vil of the ASME Section Xl Code by the Performance Demonstration Initiative (PDl) for examination of the subject nozzle-to-vessel shell welds.

The Electric Power Research Institute (EPRI) computer modeling report (Reference 1) was generated to assist NMC in developing and qualifying Ultrasonic Test (UT) examination techniques for the MNGP nozzle inner comer regions and nozzle-to-vessel shell welds. The examinations were performed using a manual contact method from the nozzle outside blend radius and vessel shell surfaces as discussed in the EPRI modeling report and as stated in MNGP procedures. The UT scanning methodology modeled in the EPRI modeling report was applicable to the coverage for the inner corner regions and for the inner 15 percent volume of the nozzle-to-vessel shell welds when scanning parallel to the weld. The examination of the remaining outer 85 percent volume of the nozzle-to-vessel shell welds was based on a separate qualified technique and procedure which did not require use of the EPRI computer modeling report to validate.

The examinations for which relief was requested were not those modeled in the EPRI report for the inner 15 percent of the nozzle-to-vessel shell welds when scanning parallel to the weld. The UT examinations which were limited in coverage involved the remaining outer 85 percent of the required volume when scanning parallel to the weld, and the exam volume required when scanning normal to the weld. Therefore, the utilization of the EPRI computer modeling report for the MNGP has no bearing on the UT examination limitations included in the requested relief.

REFERENCE

1. EPRI Internal Report IR-2004-63, "Monticello Nozzle Inner Radius and Nozzle-to-Shell Weld Examinations."

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