ML18309A264
| ML18309A264 | |
| Person / Time | |
|---|---|
| Site: | NuScale |
| Issue date: | 11/05/2018 |
| From: | NRC |
| To: | NRC/NRO/DLSE/LB1 |
| References | |
| Download: ML18309A264 (4) | |
Text
NuScaleDCRaisPEm Resource From: Cranston, Gregory Sent: Monday, November 5, 2018 2:29 PM To: Request for Additional Information Cc: Lee, Samuel; Mitchell, Matthew; McMurray, Nicholas; Tabatabai, Omid; Chowdhury, Prosanta; NuScaleDCRaisPEm Resource
Subject:
Request for Additional Information No. 510 eRAI No. 9631 (6.2.6)
Attachments: Request for Additional Information No. 510 (eRAI No. 9631).pdf Attached please find NRC staffs request for additional information (RAI) concerning review of the NuScale Design Certification Application.
Please submit your technically correct and complete response by December 31, 2018, RAI to the NRC Document Control Desk.
If you have any questions, please contact me.
Thank you.
1
Hearing Identifier: NuScale_SMR_DC_RAI_Public Email Number: 549 Mail Envelope Properties (BN1PR09MB025837D76D9F80F66F5C48E890CA0)
Subject:
Request for Additional Information No. 510 eRAI No. 9631 (6.2.6)
Sent Date: 11/5/2018 2:29:07 PM Received Date: 11/5/2018 2:29:13 PM From: Cranston, Gregory Created By: Gregory.Cranston@nrc.gov Recipients:
"Lee, Samuel" <Samuel.Lee@nrc.gov>
Tracking Status: None "Mitchell, Matthew" <Matthew.Mitchell@nrc.gov>
Tracking Status: None "McMurray, Nicholas" <Nicholas.McMurray@nrc.gov>
Tracking Status: None "Tabatabai, Omid" <Omid.Tabatabai-Yazdi@nrc.gov>
Tracking Status: None "Chowdhury, Prosanta" <Prosanta.Chowdhury@nrc.gov>
Tracking Status: None "NuScaleDCRaisPEm Resource" <NuScaleDCRaisPEm.Resource@nrc.gov>
Tracking Status: None "Request for Additional Information" <RAI@nuscalepower.com>
Tracking Status: None Post Office: BN1PR09MB0258.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 351 11/5/2018 2:29:13 PM Request for Additional Information No. 510 (eRAI No. 9631).pdf 87725 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:
Recipients Received:
Request for Additional Information No. 510 (eRAI No. 9631)
Issue Date: 11/05/2018 Application
Title:
NuScale Standard Design Certification 048 Operating Company: NuScale Power, LLC Docket No.52-048 Review Section: 06.02.06 - Containment Leakage Testing Application Section: 6.2.6 QUESTIONS 06.02.06-27 NuScale's letter, "NuScale Power, LLC Response to NRC Request for Additional Information No. 295 (eRAI No.
9216) on the NuScale Design Certification Application," dated February 12, 2018 (ADAMS Accession No. ML18043B167) partially describes their justification requesting an exemption to the 10 CFR Part 50, Appendix J and 10 CFR 50.12(a)(1) Type A leak rate test.
NuScale's Letter, "NuScale Power, LLC Response to NRC Request for Additional Information No.433 (eRAI No.
9474) on the NuScale Design Certification Application," dated September 23, 2018 (ADAMS Accession No. ML18267A403) provided additional justification.
The staff also reviewed NuScale Technical Report (TR), TR-1116-51962-NP, "NuScale Containment Leakage Integrity Assurance Technical Report," Revision 0, and the Revision 1 edits documented in RAI 9474. Section 5 of the TR describes the inservice inspection (ISI) and inservice testing (IST), and states that these programs are required "to ensure leakage integrity is maintained." Furthermore, the TR states that the ISI and IST programs are an integral part of the Containment Leakage Integrity Program (CLIP). Section 5.1 of the TR also states that ISI "ensures that a degradation mechanism is detected and addressed before CNV integrity is threatened."
Section 5.1.1 of the TR states that, "Based on the high pressure and the safety function of the CNV, NuScale determined that enhanced inspection requirements are needed for the CNV. Therefore, NuScale will inspect the CNV to ASME Class 1 requirements." These requirements are located in Section III and Section XI of the ASME Code. The staff reviewed the ASME Section III and Section XI requirements within the context of the NuScale RAI responses and TR.
ASME Section III has less stringent materials qualification, identification, and fracture toughness testing requirements for threaded fasteners with a nominal size of 1" and less. ASME Section XI, "Table IWB-2500-1 (B-G-2), Examination Category B-G-2, Pressure-Retaining Bolting, 2 in. (50 mm) and Less in Diameter," states that threaded fasteners are required to receive a VT-1 only when a connection is disassembled or bolting is removed during the inspection interval.
All of the containment vessel (CNV) threaded fasteners except for the main flange are 2" and less. Furthermore, there are sets of CNV threaded fasteners that are 1" and less. NuScale's reply to RAI 9216, Question 06.02.06-18 stated that several flanges are not expected to be disassembled for the life of the plant. In addition, NuScale stated that other flanges are not expected to be disassembled for the life of the plant unless maintenance is required.
Therefore, the staff's understanding of the ASME Code requirements and the NuScale design is that the set of the CNV threaded fasteners 1" and less will not receive the materials qualification, identification, and fracture toughness testing requirements that the larger CNV threaded fasteners receive. In addition, based on NuScale's RAI response and the ASME Section XI requirements related to threaded fasteners 2" and less in diameter, at least 47% of the CNV threaded fasteners are not expected to be inspected for the life of the plant.
Based on their importance to safety in accordance with the associated NuScale ILRT exemption request, all threaded fasteners that perform a containment leakage integrity function should have requirements that ensure containment performance. Therefore, based on the above observations and NuScale's statements in Section 5 of the TR, in order to support their justification requesting an exemption to the 10 CFR Part 50, Appendix J and 10 CFR 50.12(a)(1) Type A leak rate test, NuScale should provide augmented requirements for the aforementioned threaded fasteners that are similar to the threaded fasteners that are greater than 2". For example, x Apply the materials qualification (NCA-3812, NCA-3860, NB-2600), identification (NCA-3856), fracture toughness testing (NB-2300), and other size related requirements for threaded fasteners greater than 1" to all containment vessel (CNV) threaded fasteners with a nominal size of 1" and less (approximately 60).
x Apply the fabrication inspections in NB-2581, NB-2583 or NB-2584, and NB-2586 after fabrication threading (VT, MT or PT, and UT after fabrication threading) to the CNV threaded fasteners (entire population of approximately 500).
x Apply augmented "as-left" volumetric (UT) ISI of 25% of CNV threaded fasteners of diameter 2" and less after removal and reinstallation during a refueling outage (approximately 60 inspections per refueling outage).
x Apply augmented in-situ volumetric (UT) ISI of 25% of the CNV threaded fasteners that are not removed during an inspection interval of diameter 2" and less (approximately 60 inspections per interval).
x If a defect is found during the above augmented inservice inspections, expand the sample size to a second 25% sample of the CNV penetration threaded fastener population. If the second 25% sample does not meet the acceptance criteria, then inspect 100% of the CNV penetration threaded fastener population.
The proposed augmented fabrication requirements would apply to the set of CNV threaded fasteners that are 2" and less to provide assurance that the initially procured threaded fasteners are defect free. The proposed inservice inspections and sample sizes would provide assurance that degradation mechanisms are detected and addressed before CNV integrity is threatened, and detect issues potentially common to the other threaded fasteners. None of these proposals request the disassembly of components that NuScale does not plan on removing as part of their normal refueling and maintenance activities. Finally, the use of volumetric inspections on components while the CNV is in the dry dock imposes minimal burden while providing meaningful inspection results.