ML21036A082
| ML21036A082 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 03/12/2021 |
| From: | Nancy Salgado Plant Licensing Branch III |
| To: | Peter Dietrich DTE Electric Company |
| Arora S | |
| References | |
| EPID L-2020-LLR-0072, RR-A42 | |
| Download: ML21036A082 (14) | |
Text
March 12, 2021 Mr. Peter Dietrich Senior Vice President and Chief Nuclear Officer DTE Energy Company Fermi 2 - 260 TAC 6400 North Dixie Highway Newport, MI 48166
SUBJECT:
FERMI 2 - RELIEF REQUEST RR-A42 FOR INSERVICE INSPECTION IMPRACTICALITY DURING THE THIRD 10-YEAR INSERVICE INSPECTION INTERVAL (EPID L-2020-LLR-0072)
Dear Mr. Dietrich:
By letter dated April 30, 2020, Agencywide Documents Access and Management System (ADAMS) Accession No. ML20121A132, DTE Energy Company (DTE, the licensee), submitted relief request RR-A42 to the U.S. Nuclear Regulatory Commission (NRC). The relief request identified certain weld locations for which less than the required examination coverage was obtained due to impracticality because of interference or geometry.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Section 50.55a(g)(5)(iii), the licensee requested relief from the examination coverage requirements of Section XI, Rules for Inservice Inspection (ISI) of Nuclear Power Plant Components, of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), applicable to certain ASME Code component examinations at Fermi. The relief is requested on the basis that achieving the ASME Code-required volumetric examination coverage for the welds listed in RR-A42 was impractical.
The NRC staffs evaluation of licensees request concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(5)(iii). Based on its review, the NRC staff grants relief from the ASME Code examination requirements for the welds included in RR-A42 for the third 10-year ISI interval, which ended on May 1, 2019.
All other ASME Code,Section XI, requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
If you have any questions, please contact the Project Manager, at 301-415-1421 or e-mail at Surinder.Arora@nrc.gov.
Sincerely, Nancy L. Salgado, Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-341
Enclosure:
Safety Evaluation cc: ListServ Nancy L.
Salgado Digitally signed by Nancy L. Salgado Date: 2021.03.12 06:09:04 -05'00'
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST RR-A42 THIRD 10-YEAR INTERVAL INSERVICE TESTING FERMI 2 DOCKET 50-341
1.0 INTRODUCTION
By letter dated April 30, 2020 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20121A132), DTE Energy Company (the licensee), submitted relief request RR-A42 to the U.S. Nuclear Regulatory Commission (NRC or Commission) for the third 10-year ISI interval at Fermi 2 Power Plant (Fermi 2). In its submittal of RR-A42, the licensee requested relief from the examination coverage requirements of Section XI, Rules for Inservice Inspection [ISI] of Nuclear Power Plant Components, of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), applicable to certain ASME Code component examinations at Fermi 2.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii),
the licensee requested relief on the basis that achieving the ASME Code-required volumetric examination coverage for the subject components in RR-A42 is impractical.
2.0 REGULATORY EVALUATION
Pursuant to 10 CFR 50.55a(g)(4), Inservice Inspection [ISI] Standards Requirement for Operating Plants, components (including supports) that are classified as ASME Code Class 1, Class 2, and Class 3 must meet the requirements in 10 CFR 50.55a throughout the service life of a boiling-or pressurized-water reactor (BWR or PWR), except design and access provisions and preservice examination requirements set forth in the ASME Code to the extent practical within the limitations of design, geometry, and materials of construction of the components.
Paragraph (g) of 10 CFR 50.55a also states that ISI of the ASME Code, Class 1, 2, and 3 components is to be performed in accordance with Section XI of the ASME Code and applicable addenda, except where specific relief has been granted by the NRC, or when using the optional ASME Code Cases listed in Regulatory Guide (RG) 1.147.
The regulations also require, during the first 10-year ISI interval and during subsequent intervals, that the licensees ISI program complies with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference into 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the conditions listed therein.
Pursuant to 10 CFR 50.55a(g)(5)(iii), ISI program update: Notification of impractical ISI Code requirements, if the licensee has determined that conformance with an ASME Code
requirement is impractical for its facility, the licensee must notify the NRC and submit, as specified in § 50.4, information to support the determinations. Determinations of impracticality in accordance with 50.55a(g)(5)(iii) must be based on the demonstrated limitations experienced when attempting to comply with the ASME Code requirements during the ISI interval for which the request is being submitted. Requests for relief made in accordance with 50.55a(g)(5)(iii) must be submitted to the NRC no later than 12 months after the expiration of the initial or subsequent 120-month inspection interval for which relief is sought.
Pursuant to 10 CFR 50.55a(g)(6)(i), Impractical ISI requirements: Granting of relief, the Commission will evaluate determinations under paragraph (g)(5) of 50.55a that ASME Code requirements are impractical. The Commission may grant such relief and may impose such alternative requirements 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.
Based on the above, and subject to the following technical evaluation, the NRC staff finds that regulatory authority exists for the licensee to request and the NRC to grant the relief requested by the licensee.
3.0 TECHNICAL EVALUATION
3.1 Summary of Request The licensees RR-A42 is for multiple ASME Code components associated with multiple Section XI Examination Categories for Fermi 2s third 10-year ISI interval. The licensee stated that for the subject components, it was impractical to meet the ASME Code-required examination volumes. Specifically, due to original design of these components, it was not possible to effectively perform the examination to the extent required by the Code. The licensee stated that based on the component configuration, no significant increase in coverage of the subject components was possible with the available equipment and procedures.
The licensee indicated that it performed the ASME Code-required examinations to the maximum extent possible. Due to design limitation, there are no viable alternative examination techniques currently available to increase the coverage. Therefore, pursuant to 10 CFR 50.55a(g)(5)(iii),
the licensee requested relief on the basis that achieving the ASME Code-required volumetric examination coverage for the subject components in RR-A42 is impractical.
The ASME Code of record at Fermi 2 for the third 10-year ISI interval is the 2001 Edition through the 2003 Addenda of ASME Code,Section XI. The third 10-year ISI interval at Fermi began on May 2, 2009 and ended on May 1, 2019. For clarity, the NRC staff evaluation of RR-A42 is documented according to each of the applicable ASME Code-required examination categories.
3.2 Examination Category B-A, B-D, B-G-1, and C-B, Volumetric Examinations 3.2.1 Applicable Code Requirements The examination requirements for Examination Category B-A, Item Nos. B1.12, B1.21, B1.22 and B1.40; Examination Category B-D, Item No. B3.90; and Examination Category B-G-1, Item No. B6.40 are provided in ASME Code,Section XI, Table IWB-2500-1. The examination
requirements for Examination Category C-B, Item No. C2.21 are provided in ASME Code,Section XI, Table IWC-2500-1. For Item Nos. B1.12, B1.21, B1.22, and B1.40, the required examination volume consists of essentially 100 percent volumetric examination. The required examination volume for Item No. B3.90 is delineated in ASME Code,Section XI, Figure IWB-2500-7. The required examination volume for Item No. B6.40 is delineated in ASME Code,Section XI, Figure IWB-2500-12. The required examination volume for Item No. C2.21 is delineated in ASME Code,Section XI, Figure IWC-2500-4. Table 1 below provides a summary of the examination results for Fermi 2 Examination Categories B-A, B-D, B-G-1, and C-B, examinations for which the licensee is seeking relief.
Table 1 - Examination Category B-A, B-D, B-G-1, and C-B with Limited Volumetric Coverage Item No.
Component Identification and System Limitation /
Coverage Materials Examination Results B1.22 RPV Head Meridional Weld Top Head Lifting Lug welded over meridional weld 78.8% Volumetric SA-533 Grade B No recordable indications B1.22 RPV Head Meridional Weld Top Head Lifting Lug welded over meridional weld 78.8% Volumetric SA-533 Grade B No recordable indications B1.22 RPV Head Meridional Weld Top Head Lifting Lug welded over meridional weld 78.8% Volumetric SA-533 Grade B No recordable indications B1.22 RPV Head Meridional Weld Top Head Lifting Lug welded over meridional weld 78.8% Volumetric SA-533 Grade B No recordable indications B1.22 RPV Head Meridional Weld Control Rod Drive system and Skirt Attachment welds obstruct access 0% Volumetric SA-533 Grade B N/A B1.22 RPV Head Meridional Weld Control Rod Drive system and Skirt Attachment welds obstruct access 0% Volumetric SA-533 Grade B N/A
Table 1 - Examination Category B-A, B-D, B-G-1, and C-B with Limited Volumetric Coverage Item No.
Component Identification and System Limitation /
Coverage Materials Examination Results B1.22 RPV Head Meridional Weld Control Rod Drive system and Skirt Attachment welds obstruct access 0% Volumetric SA-533 Grade B N/A B1.22 RPV Head Meridional Weld Control Rod Drive system and Skirt Attachment welds obstruct access 0% Volumetric SA-533 Grade B N/A B1.22 RPV Head Meridional Weld Control Rod Drive system and Skirt Attachment welds obstruct access 0% Volumetric SA-533 Grade B N/A B1.22 RPV Head Meridional Weld Control Rod Drive system and Skirt Attachment welds obstruct access 0% Volumetric SA-533 Grade B N/A B1.22 RPV Head Meridional Weld Control Rod Drive system and Skirt Attachment welds obstruct access 0% Volumetric SA-533 Grade B N/A B1.21 RPV Head Circumferential Weld Control Rod Drive system and Skirt Attachment welds obstruct access 0% Volumetric SA-533 Grade B N/A B1.12 RPV Longitudinal Shell Weld Vessel Insulation Package clearance and Guide Rod 74% Volumetric SA-533 Grade B No recordable indications
Table 1 - Examination Category B-A, B-D, B-G-1, and C-B with Limited Volumetric Coverage Item No.
Component Identification and System Limitation /
Coverage Materials Examination Results B1.40 RPV Head to Flange RPV Flange configuration and proximity to the weld 100% Surface 74% Volumetric SA-533 Grade B to SA-508 Class 2 No recordable indications B1.21 RPV Head Circumferential Weld RPV Skirt attachment proximity to the Bottom Head circumferential weld 68.9% Volumetric SA-533 Grade B No recordable indications B6.40 Stud Holes 1-68 Raised cladding on scanning surface 87.55% Volumetric SA-508 Class 2 with 309 Clad No recordable indications B3.90 RPV Head Vent Nozzle-to-Vessel Weld Configuration of the nozzle 81% Volumetric SA-508 Class 2 to SA-533 Grade B No Recordable Indications B3.90 Feedwater Nozzle-to-Vessel Weld Configuration of the nozzle and proximity of the instrument nozzle pad 68.06% Volumetric SA-508 Class 2 to SA-533 Grade B No Recordable Indications B3.90 Feedwater Nozzle-to-Vessel Weld Configuration of the nozzle 76.68% Volumetric SA-508 Class 2 to SA-533 Grade B No Recordable Indications B3.90 Feedwater Nozzle-to-Vessel Weld Configuration of the nozzle 76.68% Volumetric SA-508 Class 2 to SA-533 Grade B No Recordable Indications B3.90 Feedwater Nozzle-to-Vessel Weld Configuration of the nozzle 76.68% Volumetric SA-508 Class 2 to SA-533 Grade B No Recordable Indications B3.90 Reactor Recirculation System Nozzle-to-Vessel Weld Configuration of the nozzle 84.3% Volumetric SA-508 Class 2 to SA-533 Grade B No Recordable Indications
Table 1 - Examination Category B-A, B-D, B-G-1, and C-B with Limited Volumetric Coverage Item No.
Component Identification and System Limitation /
Coverage Materials Examination Results B3.90 Reactor Recirculation System Nozzle-to-Vessel Weld Configuration of the nozzle 87.76% Volumetric SA-508 Class 2 to SA-533 Grade B No Recordable Indications B3.90 Reactor Recirculation System Nozzle-to-Vessel Weld Configuration of the nozzle 87.76% Volumetric SA-508 Class 2 to SA-533 Grade B No Recordable Indications C2.21 Residual Heat Removal Heat Exchanger Nozzle-to-Shell Weld Nozzle-to-shell weld face angle limits direct scanning of the inner 1/3 code volume 100% Surface 73.86% Volumetric SA-105 to SA-516 Grade 70 No Recordable Indications 3.2.2 Licensees Reason for Request Due to the original design of these components, the licensee stated that it was not possible to obtain the ASME Code-required examination coverage for volumetric examinations for the pressure vessel welds. The licensee stated that the subject welds and components were examined to the maximum extent possible. However, due to physical interferences it was not possible to examine essentially 100 percent of the required examination volume. The licensee stated that there were no instances where these components could have been conditioned to obtain the required examination coverage without major modification to the components. The summary of the examination results for Examination Categories B-A, B-D, B-G-1, and C-B, component examinations for which the licensee is seeking relief are provided in Table 1 above.
3.2.3 NRC Staff Evaluation of Category B-A, B-D, B-G-1, and C-B, Volumetric Examinations The NRC staff noted a minor error in the licensees application. In Table 1 of Enclosure 1 to the submittal, the licensee categorized reactor pressure vessel head meridional welds as Item No. B1.21. However, Table IWB-2500-1 of the 2001 Edition of Section XI categorizes such welds as Item No. B1.22. The staff corrected this minor discrepancy in Table 1 of this safety evaluation.
Examination Categories B-A and B-D, Item Nos. B1.12 and B1.21, B1.22, and B1.40, require essentially 100 percent volumetric examinations covering the examination volume delineated in ASME Code,Section XI, Figure IWB-2500-2, for Item No. B1.12, Figure IWB-2500-3, for Item Nos. B1.21 and B1.22, and Figure IWB-2500-5 for Item No. B1.40. However, the licensees volumetric examinations were restricted by component design, materials, and weld configurations. For example, the licensee demonstrated that the raised clad flange seal surface interfered with probe positioning when performing the threads in flange examination (see
to Enclosure 1 of the licensees submittal). These conditions precluded the licensee from obtaining full access to these welds, resulting in limited volumetric examinations.
The staff reviewed the photographs and diagrams in Attachments 1-12 to Enclosure 1 of the licensees submittal and confirmed the various geometric limitations associated with performing the required examinations. To gain access for achieving examination coverage for the required examination volumes, the subject welds would require design modifications. Given the burden imposed on the licensee associated with major design modification to the plant, obtaining essentially 100 percent of ASME Code-required volumetric examinations for the subject components is considered impractical.
Based on the aggregate coverage obtained for the subject components, the extent of the examinations, and considering the licensees performance of essentially 100 percent examination coverage for the accessible portions of these welds, it is reasonable to conclude that, had significant flaws been present in these welds, some evidence of unacceptable flaws would have been detected by the licensee. However, the lower head meridional and circumferential welds (designated as 2-306A through 2-306G by the licensee) are completely obstructed by the control rod drives and incore monitoring tubes. As such, the licensee obtained zero coverage of these welds. The licensee performed limited coverage examinations of similar welds, such as the circumferential weld near the bottom head (weld 6-306) and found no recordable indications. The licensee stated that there is no new degradation mechanism in the missed areas that would increase risk to structural integrity relative to the examined regions.
Furthermore, the licensee performs periodic system pressure tests in accordance with ASME Code,Section XI, Examination Category B-P. In total, these considerations provide reasonable assurance of the integrity of the lower head welds.
Based on its review of the Examination Categories B-A, B-D, B-G-1, and C-B, components at Fermi 2, the NRC staff finds that it is impractical to meet the ASME Code-required examination coverage for the subject welds due to the original design configuration for the subject welds and components. The NRC staff also determined that the ultrasonic (UT) examinations performed, despite the limited coverage obtained by the licensee, provide reasonable assurance of the structural integrity for the subject components. Furthermore, the continued performance of the required visual testing (VT-2) examinations through the system pressure tests provide additional assurance of structural integrity of the subject piping components. Therefore, the staff finds the licensees request for relief acceptable.
3.3 Examination R-A, Pressure-Retaining Welds in Piping 3.3.1 Applicable Code Requirements Examination Category R-A, Item No. R1.16, is related to licensees use of its RI (risk-informed)
ISI program, and portions of ASME Code Case N-578-1, Alternative Piping Classification and Examination Requirements,Section XI, Division 1. The NRC staff approved licensees use of the Fermi 2 RI-ISI program for the third 10-year ISI interval, by letter dated October 1, 2010 (ADAMS Accession No. ML102590586). Item No. R1.16 is designated for piping welds that are susceptible to degradation due to intergranular or transgranular stress corrosion cracking (IGSCC or TGSCC). These welds are also subsumed by licensees augmented inspections in accordance with Boiling Water Reactor Vessel and Internals Project (BWRVIP)-75-A, BWR Vessel and Internals Project Technical Basis for Revisions to Generic Letter 88-01 Inspection Schedules. Additionally, the licensee stated that all of its reactor coolant welds correspond to BWRVIP-75-A, Category A (resistant to IGSCC) or Category B (not resistant to IGSCC but treated for stress mitigation).
Examination Category R-A, for Item No. R1.16 (see Table 2 below), the required examination consists of essentially 100 percent volumetric examination. The required examination volumes are delineated in ASME Code,Section XI, Figures IWB-2500-8(c), IWB-2500-9, 10, or 11.
Table 2 - Examination Category R-A Welds with Limited Volumetric Coverage Item No.
Component Identification and System Limitation/Co verage Pipe Size (inch)
Materials Examination Results R1.16 FW-E11-2327-6W0 RHR/LPCI System Pipe to Tee Weld Single sided examination 50% coverage 24 Austenitic Stainless Steel No Recordable Indications R1.16 FW-G33-3096-12WF3 RWCU System Sweepolet-to-Tee Weld Single sided examination 50% coverage 4
Austenitic Stainless Steel No Recordable Indications R1.16 FW-RD-2-A11 RECIR System Sweepolet-to-Pipe Weld Single sided examination 50% coverage 12 Austenitic Stainless Steel No Recordable Indications R1.16 SW-RD-2-A3-W7 RECIRC System Cross-to-Pipe Weld Single sided examination 50% coverage 22 Austenitic Stainless Steel No Recordable Indications R1.16 SW-RS-2-A3-W4 RECIRC System Sweepolet-to-Pipe Weld Single sided examination 50% coverage 4
Austenitic Stainless Steel No Recordable Indications R1.16 SW-RS-2-A3-W5 RECIRC System Pipe-to-Flange Weld Single sided examination 50% coverage 4
Austenitic Stainless Steel No Recordable Indications R1.16 SW-RS-2-B3-W4 RECIRC System Sweepolet-to-Pipe Weld Single sided examination 50% coverage 4
Austenitic Stainless Steel No Recordable Indications R1.16 SW-RS-2-B3-W5 RECIRC System Pipe-to-Flange Weld Single sided examination 50% coverage 4
Austenitic Stainless Steel No Recordable Indications 3.3.2 Licensees Reason for Request Due to component design limitations, the licensee was unable to obtain the ASME Code-required examination coverage for the subject Examination Category R-A welds identified in its submittal. The licensee stated that for the subject austenitic stainless steel welds it was impractical to obtain the required essentially 100 percent volumetric coverage, due to access being limited to a single side only. Therefore, only 50 percent credit was taken for these welds based on ASME Section XI, Appendix VIII, UT procedure demonstration. A summary of the examination results is provided in Table 2 above.
Examination Category R-A, Item No. R1.16, welds, Nos. FW-E11-2327-6W0, FW-G33-3096-12WF3, FW-RD-2-A11, SW-RD-2-A3-W7, SW-RS-2-A3-W4, SW-RS-2-A3-W5, SW-RS-2-B3-W4, and SW-RS-2-B3-W5, are all ASME Code Class 1, austenitic stainless steel piping welds for which due to design constraints the license was not able to achieve the ASME Code-required examination coverage (i.e., essentially 100 percent). The licensee was able to achieve only 50 percent of the required examination volume. There were no indications recoded as a result of these volumetric examinations. The licensee stated that no significant increase in coverage was possible with available equipment and procedures based on component configuration. Therefore, it determined that further attempts to meet the ASME Code-required examination coverage for the subject welds was impractical.
3.3.3 NRC Staff Evaluation of Examination Category R-A Welds Examination requirements of ASME Code Case N-578-1, Examination Category R-A, Item No.
R1.16, require essentially 100 percent volumetric examination covering the examination volume delineated in ASME Code,Section XI, Figures IWB-2500-8(c),IWB-2500-9, IWB-2500-10, and IWB-2500-11, as applicable. However, the licensees volumetric examinations are restricted by component design, materials of fabrication, and weld configurations. These conditions precluded the licensee from obtaining full access from both sides of these welds, resulting in limited volumetric examinations. Given the limitations of currently available inspection technology, the licensee would require design modifications to gain additional access for achieving the required examination volumes. This would place a burden on the licensee.
Therefore, obtaining essentially 100 percent of ASME Code-required volumetric examinations for the subject welds is considered impractical.
The licensee further stated that all of the ASME Code Class 1, austenitic stainless welds at Fermi 2 that are subject to IGSCC were mitigated by stress improvement prior to 2 years of service. The licensee stated that no significant increase is coverage was possible with available equipment and procedures based on component configuration. Therefore, it determined that further attempts to meet the ASME Code-required coverage for the subject welds was impractical. Fermi 2 performed UT examinations, using personnel, equipment, and procedures qualified in accordance with ASME Code,Section XI, Appendix VIII, as implemented by the Performance Demonstration Initiative (PDI).
As shown in the sketches and technical descriptions included in the licensees submittal, the subject welds are all austenitic stainless steel piping welds with geometric limitations that restricted performing UT scanning from both sides of the welds. However, volumetric examinations on the subject welds were conducted with equipment, procedures, and personnel that were qualified to a performance demonstration process outlined in the ASME Code,Section XI, Appendix VIII. These techniques have been qualified through the industrys PDI, which meets the intent of the ASME Code,Section XI, Appendix VIII, requirements for flaws located on the near-side of the welds; far-side detection of flaws is considered to be a best effort. The NRC staff finds that the licensees achieved examination coverage constitutes a best effort, and is considered justified and acceptable.
For welds, Nos. FW-E11-2327-6W0, FW-G33-3096-12WF3, FW-RD-2-A11, SW-RD-2-A3-W7, SW-RS-2-A3-W4, SW-RS-2-A3-W5, SW-RS-2-B3-W4, and SW-RS-2-B3-W5, the licensee obtained 50 percent coverage with no recordable indications. The UT techniques employed for these welds met the ASME Code,Section XI, Appendix VIII, requirements for austenitic stainless steel welds. As stated earlier, they have been qualified for flaws located on the near-
side, not the far-side of the welds and far-side detection of flaws is considered to be a best effort. However, the NRC staff expects that had significant flaws been present on the far-side, they would have been detected by the licensee.
The NRC staff finds that for the Fermi 2 welds, Nos. FW-E11-2327-6W0, FW-G33-3096-12WF3, FW-RD-2-A11, SW-RD-2-A3-W7, SW-RS-2-A3-W4, SW-RS-2-A3-W5, SW-RS-2-B3-W4, and SW-RS-2-B3-W5, the licensee has demonstrated that due to geometric limitations it was impractical to meet the ASME Code-required volumetric examination coverage for the subject piping welds during its third 10-year ISI interval. Although the ASME Code-required coverage could not be obtained, the UT techniques employed provided nearly full volumetric coverage from the near-side of the welds, which also provides some limited volumetric coverage for the weld materials on the opposite (far) side of these welds. Based on the aggregate coverage obtained for the subject welds, the extent of the examinations, and considering the licensees performance of essentially 100 percent examination coverage for the accessible portions of these welds, it is reasonable to conclude that, had significant flaws been present in these welds, some evidence of unacceptable flaws would have been detected by the licensee. Furthermore, the NRC staff noted that the licensee had taken actions to mitigate IGSCC during initial construction and has not detected cracking associated with IGSCC. Therefore, the staff determined that the examinations performed provide reasonable assurance of structural integrity of the subject welds.
Based on its review of the subject Examination Category R-A welds at Fermi 2, the NRC staff finds that it is impractical to meet the ASME Code-required examination coverage for the subject welds due to the design configuration of the components. The NRC staff also determined that the examinations performed, despite the limited coverage obtained by the licensee, provide reasonable assurance of the structural integrity for the subject component welds. Furthermore, the staff finds that the continued performance of the periodic, required VT-2 examinations through the system pressure tests provide additional assurance of structural integrity of the subject piping components. Hence, the staff finds that the risk associated with granting the requested relief would be very low. Therefore, the staff finds the licensees request acceptable.
4.0 CONCLUSION
As set forth above, the NRC staff has determined that granting relief pursuant to 10 CFR 50.55a(g)(6)(i) is authorized by law and will not endanger life or property, or the common defense and security, and is otherwise in the public interest, given due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. Furthermore, the NRC staff concluded that the examinations performed to the extent practical provide reasonable assurance of structural integrity of the subject components. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(5)(iii). Therefore, the NRC staff grants relief from the ASME Code examination requirements for the welds included in RR-A42 for Fermi for the third 10-year ISI interval, which ended on May 1, 2019.
All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributors:
M. Benson R. Kalikian Date:
March 12, 2021
- By e-mail OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DNRL/NVIB/BC*
NRR/DORL/LPL3/BC NAME SArora SRohrer HGonzalez NSalgado DATE 02/05/2021 02/8/2021 12/04/2020 03/12/2021