ML102780190

Draft Request for Additional Information, Relief Request RR-12, from Requirements of ASME Code Case N-722 for Fourth 10-Year Inservice Inspection Interval (ME4541)

ML102780190
Person / Time
Site:	Fort Calhoun
Issue date:	10/04/2010
From:	Lynnea Wilkins Plant Licensing Branch IV
To:	Hansher B Omaha Public Power District
Wilkins, L E, NRR/DORL/LPL4, 415-1377
References
TAC ME4541
Download: ML102780190 (1)

Text

ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION REQUEST FOR RELIEF FROM ASME CODE CASE N-722 REQUIREMENTS FOR VISUAL EXAMINATION OF REACTOR VESSEL HOT LEG NOZZLE TO SAFE END WELDS OMAHA PUBLIC POWER DISTRICT, FORT CALHOUN STATION, UNIT NO. 1, DOCKET NO. 50-285 By letter dated August 16, 2010, Omaha Public Power District (the licensee), proposed an alternative to 10 CFR 50.55a(g)(6)(ii)(E) for Fort Calhoun Station, Unit 1. This requirement defines the inservice inspection frequency of visual examination of the reactor vessel hot leg nozzle to safe end welds in accordance with American Society of Mechanical Engineer's Boiler and Pressure Vessel Code Case N-722, "Additional Examinations for PWR Pressure Retaining Welds in Class 1 Components Fabricated With Alloy 600/82/182 Materials," and with NRC conditions. The duration of request is for the fourth 10-year ISI interval which ends on September 25, 2013.

The NRC staff has reviewed and evaluated the information provided by the licensee and has determined that the following information is needed in order to complete its review of the relief request. 1. The NRC staff requests the licensee's basis for not performing a visual, volumetric or inside surface examination of each weld necessary to meet the inspection requirements of 10 CFR 50.55a(g)(6)(ii)(E). If visual, volumetric or inside surface examinations could be performed on each penetration nozzle to meet the current inspection requirements, the NRC staff finds insufficient basis to grant relief under 10 CFR 50.55a(a)(3)(i), as not performing the examination does not provide the same level of assurance as the current inspection requirements. However if there is a hardship, NRC staff requests the licensee's basis for relief to not perform the inspection under 10 CFR 50.55a(a)(3)(ii). 2. NRC staff requests the following references used in the Westinghouse calculation; numbers 3, 5, 6, 8, 9, 10 and 11. NRC staff will need these references quickly to have sufficient time to perform verification calculations and support the licensee's schedule. 3. NRC staff requests the 2003, 2008, and 2009 inspection data of welds designated Items 1 and 2 in Table 1 of the August 16, 2010 relief request. NRC staff requests the inspector's summary reports to verify previous inspection results, and verify basis for initial starting flaw size in flaw analysis calculations. For example, reports documentation the inspection stating "No Reportable" or "No Recordable" indications are requested. 4. In order to support the licensee's use of zinc as a mitigation method, NRC staff requires supporting technical basis documents for review. Specifically, NRC staff requests those documents that address the mitigation effectiveness of the zinc addition history at Fort Calhoun Station, Unit 1, at the current levels at 300 ppb-months, and the rate of addition of 6ppb/month. Also, provide projected rates of addition during the period of requested relief and projected accumulated concentration-time levels over the period of requested relief.