ML20231A237
| ML20231A237 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/17/2020 |
| From: | Samson Lee NRC/NRR/DORL/LPL4 |
| To: | Richardson M Pacific Gas & Electric Co |
| References | |
| L-2020-LLA-017 | |
| Download: ML20231A237 (3) | |
Text
From:
Lee, Samson Sent:
Monday, August 17, 2020 4:16 PM To:
Richardson, Michael
Subject:
Diablo Canyon additional request for additional information: Exigent License Amendment Request for application to provide a new Technical Specification 3.7.5, Auxiliary Feedwater System, Condition G (EPID: L-2020-LLA-0176)
By letter dated August 12, 2020 (Agencywide Documents Access and Management System (ADAMS)
Accession No. ML20225A303), Pacific Gas and Electric Company (PG&E or the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License Nos. DPR 80 and DPR-
- 82) for the Diablo Canyon Nuclear Power Plant (Diablo Canyon), Units 1 and 2. The proposed amendments would avoid an unnecessary plant shutdown during the expected time needed to perform potential repairs to the Unit 1 auxiliary feedwater system (AFW) piping that PG&E conservatively anticipates may be identified during Diablo Canyon, Unit 1, Cycle 22, planned upcoming inspections to the AFW system. The NRC staff has reviewed the license amendment request (LAR) and determined that additional information is required to complete the review. The NRC staff has sent requests for additional information (RAIs) on August 14, 2020. The NRC staffs additional RAIs are listed below. The staff may have additional RAIs. The staff sent the draft additional RAIs to the PG&E staff, who determined that no clarification call was necessary. The PG&E staff requested, and NRC agreed, to a RAI response by August 18, 2020.
The NRC staff considers that timely responses to RAIs help ensure sufficient time is available for staff review and contribute toward the NRCs goal of efficient and effective use of staff resources. Please note that if you do not respond to this request by the agreed-upon date or provide an acceptable alternate date, we may deny your application for amendment under the provisions of Title 10 of the Code of Federal Regulations, Section 2.108. If circumstances result in the need to revise the agreed upon response date, please contact me at (301) 415-3168 or via e-mail Samson.Lee@nrc.gov.
- 1) Basis for higher corrosion rates at Unit 2 when compared to Unit 1 Background. The August 16 submittal states Unit 2 has a higher corrosive environment compared to Unit 1 due to localized weather patterns concentrating on the Unit 2 side.
The staff seeks clarification regarding how localized weather patterns are more aggressive at Unit 2 when compared to Unit 1. Corrosion in Marine Atmospheres (located in ASM Handbook, Volume 13C: Corrosion: Environments and Industries) states that the atmospheric corrosion rates of carbon steel in a marine environment can be influenced by several factors such as distance from sea, location above sea level, direction and magnitude of air currents which transport droplets of corrosive seawater, etc. The staff also recognizing that the basis for a higher corrosive environment could be addressed through comparison of external loss of material rates; however, corrosion rate data was only provided for Unit 1 (2-8 mils/year).
Request. Provide clarification regarding why Unit 2 has a higher corrosive environment when compared to Unit 1 through providing additional information regarding localized weather patterns and/or comparison of corrosion rate data.
- 2) Clarification regarding inspection methodology for the five pipe segments on Unit 1
Background. The staff seeks clarification regarding the inspection methodology planned for the five pipe segments on Unit 1. The submittal states that ultrasonic testing methods were utilized during the Unit 2 inspections; however, the submittal also references walkdowns of Unit 1 piping conducted on July 25th and 26th. The staff notes that walkdowns are not capable of quantifying the extent of general and/or local outside metal loss patterns on the external surfaces of insulated piping.
Request. Provide clarification regarding inspection methodology for the five pipe segments on Unit 1. If ultrasonic or other volumetric examination methods will not be utilized, state the basis for how the alternative methodologies can quantify the extent of general and/or local outside metal loss patterns on the external surfaces of insulated piping.
Hearing Identifier:
NRR_DRMA Email Number:
728 Mail Envelope Properties (SA0PR09MB61868A167EEEFCB3B83465AE9A5F0)
Subject:
Diablo Canyon additional request for additional information: Exigent License Amendment Request for application to provide a new Technical Specification 3.7.5, Auxiliary Feedwater System, Condition G (EPID: L-2020-LLA-0176)
Sent Date:
8/17/2020 4:16:10 PM Received Date:
8/17/2020 4:16:10 PM From:
Lee, Samson Created By:
Samson.Lee@nrc.gov Recipients:
"Richardson, Michael" <MJRm@pge.com>
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