RBG-47370, Request for Relief from ASME Code Section XI Inservice Inspection Requirements for Reactor Pressure Vessel Support Skirt
| ML13183A067 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 06/25/2013 |
| From: | Clark J Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RBG-47370 | |
| Download: ML13183A067 (5) | |
Text
vEntergy River Bend Station 5485 U.S. Highway 61N St. Francisville, LA 70775 Tel 225-381-4177 Joseph A. Clark Manager, Licensing RBG-47370 June 25, 2013 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
REFERENCES:
Request for Relief RBS-ISI-01 8 Request for Relief from ASME Code Section XI Inservice Inspection Requirements for Reactor Pressure Vessel Support Skirt River Bend Station, Unit I Docket No. 50-458 License No. NPF-47
- 1. Entergy Letter to NRC dated September 25, 2012, Request for Relief from ASME Code Section XI Inservice Inspection Requirements for Reactor Pressure Vessel Support Skirt RBS-ISI-018 / RBG-47285)
- 2. NRC Email dated June 10, 2013, River Bend Station, Unit 1, Request for Additional Information Regarding Relief Request RBS-ISI-018 (TAC No.
ME9654)
Dear Sir or Madam:
In Reference 1, Entergy Operations, Inc. (Entergy) submitted request for relief from ASME Code Section XI Inservice Inspection Requirements for Reactor Pressure Vessel Support Skirt.
On May 29, 2013, the NRC Staff requested additional information (Reference 2) concerning this request. The Attachment provides the requested additional information.
This information contains no new commitments.
kte-e
RBG-47370 Page 2 of 2 If you have any questions or require additional information, please contact me at (225) 381-4177.
Sincerely, Manager, Licensing JAC/bmb RBF1-13-0077
Attachment:
SUPPLEMENT TO REQUEST FOR RELIEF, RESPONSE TO QUESTIONS cc:
Regional Administrator U. S. Nuclear Regulatory Commission Region IV 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125 NRC Senior Resident Inspector P. 0. Box 1050 St. Francisville, LA 70775 U. S. Nuclear Regulatory Commission Attn: Mr. Alan Wang MS 0-8B1 One White Flint North 11555 Rockville Pike Rockville, MD 20852 Mr. Jeffrey P. Meyers Louisiana Department of Environmental Quality Office of Environmental Compliance Attn. OEC - ERSD P. O. Box 4312 Baton Rouge, LA 70821-4312 Public Utility Commission of Texas Attn: PUC Filing Clerk 1701 N. Congress Avenue P. 0. Box 13326 Austin, TX 78711-3326
ATTACHMENT TO RBG-47370 SUPPLEMENT TO REQUEST FOR RELIEF RESPONSE TO QUESTIONS RBS-ISI-01 8
SUPPLEMENT TO REQUEST FOR RELIEF ENTERGY OPERATIONS, INC.
RIVER BEND STATION - UNIT 1 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING RELIEF REQUEST RBS-ISI-018 RBS-ISI-01 8 states that the reactor vessel support skirt receives a VT-3 visual examination of the entire exterior portion, and as much of the interior portion as can be accessed through the access openings, without removal of the insulation package.
Question a:
What is the estimated VT-3 visual examination coverage percentage for the inside of the RPV support skirt (10%, 20%, etc.)?
Response
The estimated VT-3 examination coverage percentage for the inside of the RPV support skirt for the examination performed in the second ISI interval was 0%.
Question b:
Please discuss whether any relevant indications (age-related degradation and/or fabrication flaws) have been discovered as a result of the limited-scope examination. If any relevant indications were found please discuss how the indications were dispositioned, in accordance with ASME Code, Section Xl requirements.
Response
No relevant indications were discovered for the exterior portion of the skirt that was examined.
Question c:
Please discuss the difficulties involved with the removal of the insulation package for performing a full examination of the inside of the reactor vessel support skirt.
Response
In Request for Relief RBS-ISI-018, Entergy stated the following:
The area inside the skirt experiences high radiological dose rates. The reactor vessel internal component configuration prevents flushing of the bottom head region to potentially reduce the dose rates. The configuration of the Control Rod Drive stub tubes under the bottom head make the use of lead shielding impractical.
Attachment to RBG-47370 Page 2 of 2 Performing the full Code examination requires removal of the insulation package which is labor intensive due to the configuration and the confined aspect of the area. The actual time required to remove the insulation package is indeterminate as it has not been previously removed in its entirety. Therefore, an accurate dose estimate for the task can not be developed at this time.
The following is supplemental information to that provided in Request for Relief RBS-ISI-018.
An insulation package surrounds the exterior of the RPV support skirt. Panels in the exterior insulation package must be removed to permit access to the interior portion of the RPV vessel support skirt via four (4) 18" X 24" manholes in the skirt. These panels are designed to be removed for this purpose. Removal of these panels allows for examination of the exterior of the RPV support skirt.
The interior surface of the RPV support skirt is covered by an insulation package designed and supplied by General Electric. The General Electric specification, the associated installation drawings and the installation manual were reviewed. The insulation package reaches from the attachment weld at the RPV bottom head downward to below the RPV support skirt flange that rests on the RPV pedestal. The insulation package is comprised of a few removable panels mechanically connected to many non-removable panels. The interior studs and nuts that fasten the RPV support skirt flange to the pedestal are located under the insulation package.
The majority of the panels of the interior insulation package are permanently installed, and were not designed to be removed. Based on the review of the associated documents, removal of the panels intended for that purpose would only allow for a small percentage of examination coverage of the interior of the RPV support skirt. In order to perform a VT-3 Visual Examination of essentially 100% of the interior portion of the RPV support skirt, the removable and all the permanent panels would have to be removed. The insulation package was not designed for disassembly in this manner.