ML19350B295
| ML19350B295 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 12/16/2019 |
| From: | Joel Wiebe NRC/NRR/DORL/LPL3 |
| To: | Torres-Cruz L Exelon Generation Co |
| References | |
| L-2019-LLA-0081 | |
| Download: ML19350B295 (4) | |
Text
From:
Wiebe, Joel Sent:
Monday, December 16, 2019 9:52 AM To:
Palutsis, Linda M:(Exelon Nuclear)
Subject:
Draft Request for Additional Information Regarding Braidwood Station, Units 1 and 2, Impractical Inservice Inspection Requirements (L-2019-LLA-0081)
- Linda, We would like to have a clarification call regarding this request within a week, if possible.
Joel In reviewing the Exelon Generation Company, LLCs (Exelons) submittal dated August 27, 2019 (ADAMS Accession No. ML19239A156), related to its request under Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii) for relief on the basis that achieving the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) inservice inspection (ISI) requirements is impractical for the Braidwood Station (Braidwood),
Units 1 and 2, the NRC staff has determined that the following information is needed in order to complete its review.
Regulatory Basis Title 10 of the Code of Federal Regulations, Part 50.55a(g)(6)(i) states:
The Commission will evaluate determinations under paragraph (g)(5) of this section that code requirements are impractical. The Commission may grant such relief and may impose such alternatives as it determines are authorized by law, will not endanger life or property or the common defense and security, and are otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
Title 10 of the Code of Federal Regulations, Part 50.55a(g)(6)(ii) states:
The Commission may require the licensee to follow an augmented inspection program for systems and components for which the Commission deems that added assurance of structural reliability is necessary.
RAI-1: The information provided in the August 27, 2019, submittal regarding the pressurizer shell-to-nozzle welds (Category B-D, Item Number B3.110) identify their material construction as Alloy 82/182. The August 27, 2019, submittal also shows these to be welds between the low alloy steel shell of the pressurizer and low alloy steel nozzle forgings. Without additional clarifying information, the NRC staff is unable to evaluate the impracticality of meeting the ASME Code requirements, whether alternatives should be imposed, and whether an augmented inspection program or other action is needed for added assurance of structural reliability. The licensee is requested to:
- 1. Confirm that the pressurizer shell-to-nozzle welds (Category B-D, Item Number B3.110) are, in fact, Alloy 82/182 welds.
- 2. Confirm that there is an Alloy 52/152 weld overlay on the Braidwood, Unit 1 weld 1PZR-01-N4A.
- 3. If the pressurizer shell-to-nozzle welds (Category B-D, Item Number B3.110) are not fabricated from Alloy 82/182 material, provide the inspection results (i.e., whether reportable indications were found) in response to this question.
RAI-2: The information provided in the August 27, 2019, submittal regarding the pressurizer shell-to-nozzle welds (Category B-D, Item Number B3.110) identify their material construction as Alloy 82/182. Historically, Alloy 82/182 (Inconel) welds in pressurized water reactors are susceptible to primary water stress corrosion cracking (PWSCC). Without additional clarifying information, the NRC staff is unable to evaluate the impracticality of meeting the ASME Code requirements, whether alternatives should be imposed, and whether an augmented inspection program or other action is needed for added assurance of structural reliability.
The licensee is requested to provide the inspection results (i.e., whether reportable indications were found) for the third 10-year ISI interval examinations of the Category B-D welds addressed in Tables I3-R18.1 and I3-R18.2 of its August 27, 2019, submittal. Since these welds are identified as having been fabricated from Alloy 82/182 material, the license is requested to justify the limited coverage obtained to date on these welds with a technical evaluation that addresses the susceptibility to PWSCC. If inspections of similar Category B-D Inconel 82/182 welds were performed during the third 10-year ISI interval, a summary of the inspection results for those welds is requested. If additional Alloy 82/182 welds were not examined, the justification should include an explanation for not examining additional or alternative accessible welds in Category B-D.
In addition, if applicable based on the answer to RAI-1, provide the results of the Braidwood, Unit 1, 1PZR-01-N4A examinations that were performed prior to the weld overlay and the results of subsequent examinations of the weld overlay including the examination results performed during the third ISI interval.
RAI-3: Provide examination results of the low alloy steel weld 2SG-01-SGC-02, which is a Tube Sheet to Barrel weld Category, C-A, Item Number C1.30, for Braidwood Unit 2. Without this additional information, the NRC staff is unable to evaluate the impracticality of meeting the ASME Code requirements, whether alternatives should be imposed, and whether an augmented inspection program or other action is needed for added assurance of structural reliability.
RAI-4: Braidwood, Unit 1 weld 1SI-39-25 is identified as having received a limited examination (i.e. only 50% of the required examination volume was examined), and two flaws were identified. Given this information, provide justification that the structural integrity of Braidwood, Unit 1 weld 1SI-39-25 is assured. Without additional information, the NRC staff is unable to evaluate the impracticality of meeting the ASME Code requirements, whether alternatives should be imposed, and whether an augmented inspection program or other action is needed for added assurance of structural reliability.
RAI-5: Several of the NDE reports in Attachment 3 for Category R-A welds did not include the examination results. Provide the examination results for the following Category R-A welds for Braidwood Unit 2. Without this additional information, the NRC staff is unable to evaluate the impracticality of meeting the ASME Code requirements, whether alternatives should be imposed, and whether an augmented inspection program or other action is needed for added assurance of structural reliability.
2FW-09-25, 2AF-03-23 (FW-1), 2AF-03-24 (FW-2), 2AF-04-20 (FW-3), 2AF-04-21 (FW-4), 2AF-02-23 (FW-1), 2AF-02-24 (FW-2), 2AF-01-24 (FW-3), 2AF-01-25 (FW-4), 2CV-21-58 (FW-1), 2CV-21-57(FW-2), and 2CV-21-56(FW-2).
Hearing Identifier:
NRR_DRMA Email Number:
351 Mail Envelope Properties (CH2PR09MB434828718E2F6C36ECF2CB9D8B510)
Subject:
Draft Request for Additional Information Regarding Braidwood Station, Units 1 and 2, Impractical Inservice Inspection Requirements (L-2019-LLA-0081)
Sent Date:
12/16/2019 9:52:06 AM Received Date:
12/16/2019 9:52:00 AM From:
Wiebe, Joel Created By:
Joel.Wiebe@nrc.gov Recipients:
"Palutsis, Linda M:(Exelon Nuclear)" <Linda.TorresCruz@exeloncorp.com>
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