ML101470496
| ML101470496 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/27/2010 |
| From: | Michael Mahoney Plant Licensing Branch III |
| To: | Lentz T FirstEnergy Corp |
| mahoney, m NRR/DORL/LPLIII-2 415-3867 | |
| References | |
| Download: ML101470496 (1) | |
Text
From:
Mahoney, Michael Sent:
Thursday, May 27, 2010 2:38 PM To:
'talentz@firstenergycorp.com'
Subject:
Davis-Besse Relief Request 10 CFR 50.55a - Reactor Pressure Vessel CRDM Pentration Nozzel - Request for Addtional Information The NRC staff requests the following information:
By email dated May 26, 2010, in response to Question # 3, the licensee stated that if PT
[penetrant testing] is used, the examination will be in accordance with Code Case N-729-1 and the 50.55a request and may include some portion of the area below the toe of the weld to ensure adequate coverage of the weld. If other surface or volumetric examination techniques (e.g. eddy current or UT) are developed and qualified per Code Case N-729-1, the qualified examination area would include, as a minimum the wetted surface of the new weld from the toe of the weld up through 0.5 inches above the rolled region of the nozzle remnant.
It is not clear to the staff the exact area below the toe of the new weld that will be examined by PT during inservice inspection.
Code Case N-729-1, Figure 2, requires inspection of Points G-F for a total of 0.25 inch distance along the reactor vessel head. This is the length of the reactor vessel head away from the J-groove weld that is required to be examined. The examination of the reactor vessel head along Points G-F is similar to the examination of the reactor vessel head below the toe of the new weld for the half nozzle repair. The purpose of the 0.25 inch examination length in the repaired nozzles is to ensure that cracking does not occur at the interface between the toe of the weld and the base metal (i.e, the reactor vessel head).
If PT is used to examine the repaired nozzles in the future inservice inspection, the staff believes that PT should cover a minimum of 0.25 inches below the toe of the new pressure boundary weld. The licensee has used PT to examine 0.5 inch below the toe of the new weld during the post-weld/preservice examination. There should not be any technical problem for examining 0.25 inches below the toe of the new weld during inservice inspection.
Thanks Mike Michael Mahoney Project Manager, Branch III-2 U. S. Nuclear Regulatory Commission Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Phone: (301)415-3867 Email: MXM15@NRC.GOV The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.
E-mail Properties Mail Envelope Properties (A41C2340DAB39B44AD0B9623285CB3330C3C68C59A)
Subject:
Davis-Besse Relief Request 10 CFR 50.55a - Reactor Pressure Vessel CRDM Pentration Nozzel - Request for Addtional Information Sent Date: 5/27/2010 2:37:37 PM Received Date: 5/27/2010 2:37:37 PM From: Mahoney, Michael Created By: Michael.Mahoney@nrc.gov Recipients:
talentz@firstenergycorp.com ('talentz@firstenergycorp.com')
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