DCL-10-164, Response to NRC Draft Request for Additional Information (Draft Set 35), Dated November 29, 2010, for License Renewal Application
| ML103480113 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 12/13/2010 |
| From: | Becker J Pacific Gas & Electric Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| DCL-10-164 | |
| Download: ML103480113 (11) | |
Text
Pacific Gas and Electric Company James R. Becker Diablo Canyon Power Plant Site Vice President Mail Code 104/ 5/ 601
- p. O. Box 56 Avila Beach, CA 93424 December 13, 2010 805.545.3462 Internal: 691.3462 Fax: 805.545.6445 PG&E Letter DCL-1 0-164 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20852 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Response to NRC Draft Request for Additional Information (Draft Set 35), dated November 29, 2010, for the Diablo Canyon License Renewal Application
Dear Commissioners and Staff:
By letter dated November 23, 2009, Pacific Gas and Electric Company (PG&E) submitted an application to the U.S. Nuclear Regulatory Commission (NRC) for the renewal of Facility Operating Licenses DPR-80 and DPR-82, for Diablo Canyon Power Plant (DCPP) Units 1 and 2, respectively. The application included the license renewal application (LRA), and Applicant's Environmental Report - Operating License Renewal Stage.
By draft request for additional information dated November 29, 2010, the NRC staff requested additional information needed to continue their review of the DCPP LRA.
PG&E's response to the request for additional information is included in Enclosure 1.
LRA Amendment 30 resulting from the responses is included in Enclosure 2 showing the changed pages with line-in/line-out annotations.
PG&E revises two commitments in revised LRA Table A4-1, License Renewal Commitments, shown in Enclosure 2.
If you have any questions regarding this response, please contact Mr. Terence L.
Grebel, License Renewal Project Manager, at (805) 545-4160.
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway . Comanche Peak . Diablo Canyon . Palo Verde . San Onofre . South Texas Project
- Wolf Creek
Document Control Desk PG&E Letter DCL-10-164 December 13, 2010 Page 2 I declare under penalty of perjury that the foregoing is true and correct.
Executed on December 13, 2010.
Site Vice President TLG/50363554 Enclosure cc: Diablo Distribution cc/enc: Elmo E. Collins, NRC Region IV Regional Administrator Nathanial B. Ferrer, NRC Project Manager, License Renewal Kimberly J. Green, NRC Project Manager, License Renewal Michael S. Peck, NRC Senior Resident Inspector Alan B. Wang, NRC Project Manager, License Renewal A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway . Comanche Peak . Diablo Canyon . Palo Verde . San Onofre . South Texas Project
- Wolf Creek
PG&E Letter DCL-10-164 Page 1 of 3 PG&E Response to NRC Draft Letter dated November 29, 2010, Request for Additional Information (Set 35) for the Diablo Canyon License Renewal Application D-RAI B2.1.17-2
Background
GALL AMP XI.M33, Selective Leaching of Materials states, in the scope of program program element, that the program includes a one-time visual inspection and hardness measurement of a selected set of sample components to determine whether loss of material due to selective leaching is not occurring for the period of extended operation.
LRA Section B2.1.17, Selective Leaching of Materials, states that the program includes a one-time visual inspection and hardness measurement or other industry-accepted mechanical inspection techniques (where feasible based on form and configuration) of selected components that may be susceptible to selective leaching to determine whether loss of material due to selective leaching is occurring.
Issue Due to the uncertainty in determining the most susceptible locations and the potential for aging to occur in other locations, the staff noted that large sample sizes (at least 20%) may be required in order to adequately confirm an aging effect is not occurring.
The applicants Selective Leaching Program does not include specific information regarding how the selected set of components will be chosen or how the sample size will be determined.
Request Provide specific information regarding how the selected set of components to be sampled will be determined and the size of the sample of components that will be inspected.
PG&E Response to D-RAI B2.1.17-2 The Selective Leaching program component types including piping, valve bodies and bonnets, pump casings, and heat exchanger components that are susceptible to selective leaching. The materials of construction for these components may include gray cast iron and copper alloys (except for inhibited brass) containing greater than 15 percent zinc or greater than 8 percent aluminum. These components may be exposed to raw water, treated water, closed cooling water, ground water, water contaminated fuel oil, or water-contaminated lube oil.
A representative sample of the component population focuses on those components most susceptible to aging due to time in service, severity of operating conditions, and lowest design margin. A sample size of twenty percent of the population with a maximum sample of 25 component inspections per unit will be established for each of
PG&E Letter DCL-10-164 Page 2 of 3 the material and environment combinations. Components will be grouped by material and environment with each group of material and environment combinations considered as a separate population.
A one-time inspection will be conducted within the 5-year period prior to the period of extended operation. For materials and environments where selective leaching is currently occurring or for materials in environments where the component has been repaired with the same material, a plant specific program will be created.
See revised LRA Appendix A1.17 and Appendix B2.1.17.
PG&E Letter DCL-10-164 Page 3 of 3 D-RAI B2.1.32-2 (follow-up)
Background:
By letter dated September 30, 2010, the applicant responded to RAI B2.1.32-2 regarding the Structures Monitoring Program inspection interval. In the response the applicant stated that the interval will be aligned with guidance in ACI 349.3R, except for the exterior of non-safety related structures, for which the interval will be no more than ten years.
Issue:
The RAI response did not provide a technical justification for an inspection interval greater than five years for the exterior of non-safety related structures.
Request:
Provide technical justification for the longer inspection interval for the exterior of nonsafety-related structures. An adequate justification should address environmental factors as well as relevant operating experience for het structures in question.
PG&E Response to D-RAI B2.1.32-2 (follow-up)
By letter dated September 30, 2010, the applicant responded to RAI B2.1.32-2 regarding the Structures Monitoring Program inspection interval. In the response the applicant stated that the Structures Monitoring Program inspection interval will be revised to be aligned with the guidance in (American Concrete Institute) ACI 349.3R, Evaluation of Existing Nuclear Safety Related Concrete Structures, Chapter 6, Evaluation Frequency, except for the exterior of non-safety related structures, for which all accessible areas of both units will be inspected at an interval of no more than ten years.
The commitment for the inspection frequency of the exterior accessible areas of non-safety related concrete structures is revised to be performed in accordance with ACI 349.3R, Evaluation of Existing Nuclear Safety Related Concrete Structures, Chapter 6, Evaluation Frequency. See revised LRA Table A4-1 in Enclosure 2.
PG&E Letter DCL-10-164 Page 1 of 6 LRA Amendment 30 LRA Section RAI Appendix A1.17 B2.1.17-2 Appendix B2.1.17 B2.1.17-2 Table A4-1 B2.1.17-2, B2.1.32-2 Appendix A PG&E Letter DCL-10-164 Final Safety Analysis Report Supplement Page 2 of 6 A1.17 SELECTIVE LEACHING OF MATERIALS The Selective Leaching of Materials program manages the loss of material due to selective leaching for gray cast iron and copper alloys (except for inhibited brass) containing greater than 15 percent zinc or greater than 8 percent aluminum brass (copper alloy >15 percent zinc), aluminum-bronze (copper alloy >8 percent aluminum),
and gray cast iron components within the scope of license renewal that are exposed to raw water, including condensation, and treated water, closed cooling water, ground water, water-contaminated fuel oil, or water-contaminated lube oil.
The Selective Leaching of Materials program includes a one-time visual inspection and hardness measurement (where feasible based on form and configuration) or other industry-accepted mechanical inspection techniques of selected components that may be susceptible to selective leaching to determine whether loss of material due to selective leaching is occurring, and whether the process will affect the ability of the components to perform their intended functions for the period of extended operation. A sample size of twenty percent of the population with a maximum sample of 25 component inspections per unit will be established for each of the material and environment combinations. If evidence of selective leaching is discovered in the implementation of the program, an engineering evaluation will determine the extent of expansion of the sample size and locations for additional inspections and evaluations.
Follow up examinations or evaluations will be performed as required to ensure component functionality during the period of extended operation.
The Selective Leaching of Materials program is a new program and the inspections will be completed within the 105-year period prior to the period of extended operation.
Appendix B PG&E Letter DCL-10-164 AGING MANAGEMENT PROGRAMS Page 3 of 6 B2.1.17 Selective Leaching of Materials Program Description The Selective Leaching of Materials program manages loss of material due to selective leaching for gray cast iron and copper alloys (except for inhibited brass) containing greater than 15 percent zinc or greater than 8 percent aluminum brass
(>15 percent zinc), gray cast iron, and aluminum-bronze (>8 percent aluminum) components within the scope of license renewal that are exposed to raw water, including condensation, and treated water, closed cooling water, ground water, water-contaminated fuel oil, or water-contaminated lube oil. The program provides measures for detecting the aging effects prior to loss of intended function, but does not prevent degradation due to aging effects. There is no monitoring and trending for the one-time inspection activity.
The Selective Leaching of Materials program includes a one-time visual inspection and hardness measurement or other industry-accepted mechanical inspection techniques (where feasible based on form and configuration) of selected components that may be susceptible to selective leaching to determine whether loss of material due to selective leaching is occurring. A sample size of twenty percent of the population with a maximum sample of 25 component inspections will be established for each of the material and environment combinations. Evidence of selective leaching discovered in the initial implementation of the program is submitted for engineering evaluation. The engineering evaluation will determine whether the potential loss of material affects the ability of the components to perform their intended function. The results of the engineering evaluation will also determine the extent of expansion of the sample size and locations for additional inspections and evaluations. Follow-up examinations or evaluations are performed as required to ensure component functionality during the period of extended operation. Industry-accepted mechanical methods of testing for selective leaching may include scraping or chipping of the surfaces.
The Selective Leaching of Materials program is a new program and the inspections will be completed within the 105-year period prior to the period of extended operation.
NUREG-1801 Consistency The Selective Leaching of Materials program is a new program that, when implemented, will be consistent with NUREG-1801,Section XI.M33, Selective Leaching of Materials.
Appendix B PG&E Letter DCL-10-164 AGING MANAGEMENT PROGRAMS Page 4 of 6 Exceptions to NUREG-1801 None Enhancements None Operating Experience The Selective Leaching of Materials program is a new program at DCPP. Therefore, there is no plant-specific operating experience for program effectiveness. Industry operating experience that forms the basis for this program is included in the operating experience element of the corresponding NUREG-1801, aging management program description. The DCPP operating experience findings for this program identified no unique plant specific operating experience; therefore DCPP operating experience is consistent with NUREG-1801. The only plant operating experience identified in the review was the response to NRC Information Notice 94-59, Accelerated Dealloying of Cast Aluminum-Bronze Valves Caused by Microbiologically Induced Corrosion, which documented an evaluation that was completed for selective leaching. Upon completing the evaluation, DCPP concluded that biocide injection, periodic inspection and cleaning had been maintaining the affected components operable. In 1997, signs of selective leaching were noted on three valves in the auxiliary saltwater system. Polished counterweights and housings were installed to slow the rate of de-alloying. Subsequent visual inspections of the subject valves, performed every 18 months, have not identified any selective leaching issues since this implementation. Therefore, the existing plant maintenance practices have proven to be adequate for identification of selective leaching and periodic inspections of valves susceptible to selective leaching.
Industry and plant-specific operating experience will be evaluated in the development and implementation of this program. As additional industry and applicable plant-specific operating experience become available, the operating experience will be evaluated and appropriately incorporated into the program through the DCPP Corrective Action Program and Operating Experience Program.
This ongoing review of operating experience will continue throughout the period of extended operation, and the results will be maintained on site. This process will confirm the effectiveness of this new program by incorporating applicable operating experience and performing self assessments of the program.
Appendix B PG&E Letter DCL-10-164 AGING MANAGEMENT PROGRAMS Page 5 of 6 Conclusion The implementation of the Selective Leaching of Materials program will provide reasonable assurance that aging effects will be managed such that the systems and components within the scope of this program will continue to perform their intended functions consistent with the current licensing basis for the period of extended operation.
Table A4-1 PG&E Letter DCL-10-164 LICENSE RENEWAL COMITTMENTS Page 6 of 6 Table A4-1 License Renewal Commitments LRA Implementation Item # Commitment Section Schedule 6 Implement the Selective Leaching of Materials program as described in LRA Section B2.1.17. B2.1.17 During the 10 5 years prior to the period of extended operation.
The Structures Monitoring Program inspection interval for safety related and non-safety related concrete structures will be revised to be aligned with the guidance in ACI 349.3R, Evaluation of Prior to the period 44 Existing Nuclear Safety Related Concrete Structures, Chapter 6, Evaluation Frequency., B2.1.32 of extended except for the exterior of non-safety related structures, for which all accessible areas of both operation units will be inspected at an interval of no more than ten years..