ML18096A614
| ML18096A614 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 06/05/2018 |
| From: | David Wrona Plant Licensing Branch III |
| To: | Polson K DTE Electric Company |
| Goetz S | |
| References | |
| EPID L-2017-LLR-0090 | |
| Download: ML18096A614 (9) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 5, 2018 Mr. Keith J. Polson Senior Vice President and Chief Nuclear Officer DTE Electric Company Fermi 2 - 260 TAC 6400 North Dixie Highway Newport, Ml 48166
SUBJECT:
FERMI 2 - RELIEF FROM THE REQUIRMENTS OF THE ASME CODE (EPID L-2017-LLR-0090)
Dear Mr. Polson:
By letter dated September 26, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17270A036), as supplemented by letters dated December 8, 2017 (ADAMS Accession No. ML17342A978) and February 6, 2018 (ADAMS Accession No. ML18037A511 ), DTE Electric Company (DTE or the licensee) submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for the use of alternatives to certain American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), Section XI, requirements at Fermi 2.
Specifically, pursuant to Title 10 of the Code of Federal Regulations ( 10 CFR),
Section 50.55a(z)(1), the licensee requested to use the proposed alternative in ASME Code Case N-702, "Alternative Requirements for Boiling Water Reactor (BWR) Nozzle Inner Radius and Nozzle to Shell Welds Section XI, Division 1," on the basis that the alternative provides an acceptable level of quality and safety.
The NRC staff reviewed the licensee's evaluation of the five criteria specified in the SE for the BWRVIP (Boiling Water Reactor Vessel and Internal Project]-241 report which provides technical bases for Code Case N-702, to examine reactor pressure vessel (RPV) nozzle-to-vessel welds and nozzle inner radii sections at Fermi 2. As set forth above, the NRC staff determined that the licensee's proposed alternative provides an acceptable level of quality and safety and applies to all requested Fermi 2 RPV nozzles with the exception of the feedwater nozzles and control rod drive return nozzles.
Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(1) and has demonstrated that they meet the conditions specified in RG 1.147, "lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1," for the use of Code Case N-702. Therefore, the NRC authorizes the licensee's proposed alternative to use Code Case N-702 for inspection of nozzle-to-vessel welds and nozzle inner radii sections of RPV nozzles listed in Section 3.1 of this SE for the duration of the third inservice interval which began on May 2, 2009, and is scheduled to end on May 1, 2019.
All other ASME Code, Section XI, requirements for which relief was not specifically requested and approved remain applicable, including third-party review by the Authorized Nuclear lnservice Inspector.
If you have any questions, please contact the project manager, Sujata Goetz, at 301-415-8004 or via e-mail at Sujata.Goetz@nrc.gov.
Sincerely, t)dJ~a. 2~ffh( '--
Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-341
Enclosure:
Safety Evaluation cc w/encl: ListServ
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST NO. RR-A37 REGARDING CODE CASE N-702 DTE ELECTRIC COMPANY FERMI NUCLEAR POWER PLANT, UNIT 2 DOCKET NO. 50-341
1.0 INTRODUCTION
By letter dated September 26, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17270A036), as supplemented by letters dated December 8, 2017 (ADAMS Accession No. ML17342A978), and February 6, 2018 (ADAMS Accession No. ML18037A511 ), DTE Electric Company (DTE or the licensee) submitted a request to the U.S. Nuclear Regulatory Commission (NRC) for the use of alternatives to certain requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) at Fermi 2.
Specifically, pursuant to Title 10 of the Code of Federal Regulations ( 10 CFR),
Section 50.55a(z)(1 ), the licensee requested to use the proposed alternative in ASME Code Case N-702, "Alternative Requirements for Boiling Water Reactor (BWR) Nozzle Inner Radius and Nozzle to Shell Welds Section XI, Division 1," on the basis that the alternative provides an acceptable level of quality and safety.
The licensee requested relief from the ASME Code for examination requirements associated with Class 1 nozzle-to-vessel weld and nozzle inner radii section, as delineated in Item No. 83.90, "Nozzle-to-Vessel Welds," and 83.100, "Nozzle Inside Radius Section," of Table IWB-2500-1, "Examination Category B-D, Full Penetration Welded Nozzles in Vessels Inspection Program." Specifically, pursuant to 10 CFR 50.55a(z)(1), the licensee requested to use the proposed alternative in Code Case N-702, on the basis that the alternative provides an acceptable level of quality and safety.
2.0 REGULATORY REQUIREMENTS Regulation 10 CFR 50.55a(g) requires the inservice inspection (ISi) of the ASME Code Class 1, 2, and 3 components be performed in accordance with Section XI of the ASME Code and applicable addenda as a way to detect anomaly and degradation indications so that structural integrity of these components can be maintained. 10 CFR 50.55a(z), states that alternatives to the requirements of paragraphs (b) through (h) or portions thereof may be used when authorized by the Director, Office of Nuclear Reactor Regulation. A proposed alternative must be submitted and authorized prior to implementation. The applicant or licensee must demonstrate that: ( 1) the proposed alternative would provide an acceptable level of quality and Enclosure
safety; or (2) compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
For all reactor pressure vessel (RPV) nozzle-to-vessel welds and nozzle inner radii sections, Section XI of the ASME Code requires 100 percent inspection during each 10-year ISi interval.
However, Code Case N-702 provides an alternative, which reduces the inspection of RPV nozzle-to-vessel welds and nozzle inner radii sections from 100 percent to 25 percent of the nozzles for each nozzle type during each 10-year interval.
Code Case N-702 was conditionally approved in Regulatory Guide (RG) 1.147, Revision 17, "lnservice Inspection Code Case Acceptability, Section XI, Division 1," dated August 2014. For application of Code Case N-702, the licensee is required to demonstrate that they have met the evaluation criteria stated in BWRVIP [Boiling Water Reactor Vessel and Internal Project]-108, "Technical Basis for the Reduction of Inspection Requirements for the Boiling Water Reactor Nozzle-to-Vessel Shell Welds and Nozzle Inner Radii," and BWRVIP-241, "Probabilistic Fracture Mechanics Evaluation for the Boiling Water Reactor Nozzle to Vessel Shell Welds and Nozzle Blend Radii," as required by RG 1.147. Specifically, RG 1.147 states:
The applicability of Code Case N-702 must be shown by demonstrating that the criteria in Section 5.0 of NRC Safety Evaluation regarding BWRVIP -108 dated December 19, 2007 [ADAMS Accession No.] (ML073600374) or Section 5.0 of NRC Safety Evaluation regarding BWRVIP-241 dated April 19, 2013 [ADAMS Accession No.] (ML13071A240) are met. The evaluation demonstrating the applicability of the Code Case shall be reviewed and approved by the NRC prior to the application of the Code Case.
The BWRVIP-108 provides the technical basis for the reduction of the nozzle-to-vessel welds and nozzle blend radii from 100 to 25 percent of the nozzles every 10 years. Supplemental analyses of BWR recirculation inlet and outlet nozzle-to-vessel welds and nozzle inner radii sections are provided BWRVIP-241. BWRVIP-241 was submitted to address the limitations and conditions specified in the BWRVIP-108 and to support the proposed revision of the five evaluation criteria in BWRVIP-108. The NRC staff SE for BWRVIP-241 accepted the proposed revision of the five evaluation criteria in BWRVIP-108. BWRVIP-108 and BWR-241 both contain probabilistic fracture mechanics analysis supporting Code Case N-702 and are for 40 years of operation.
3.0 EVALUATION 3.1 The Licensee's Request for Alternative Component(s) for which Alternative is Requested (ASME Code Class 1)
Reactor Pressure Vessel Nozzles, Unit 2: N1, N2, N3, NS, N6, N7, and N8
Examination Category 8-D, "Full Penetration Welded Nozzles in Vessels" Examination Item Nos.
83.90, "Nozzle-to-Vessel Welds" 83.100, "Nozzle Inside Radius Section"
Applicable Code Edition and Addenda
The third 10-year ISi program at Fermi 2, is based on the ASME Code, Section XI, 2001 Edition through the 2003 Addenda.
ASME Code Requirement for which Alternative is Requested The applicable requirements are contained in ASME Code Table IW8-2500-1, "Examination Category 8-D, Full Penetration Welded Nozzles in Vessels - Inspection Program 8." Class 1 Reactor Vessel nozzle-to-vessel weld and nozzle inner radii section examination requirements are delineated in Item No. 83.90, "Nozzle-to-Vessel Welds," and 83.100, "Nozzle Inside Radius Section." The required method of examination is volumetric and is to be performed once per interval on each reactor vessel nozzle-to-vessel weld and nozzle inside radius section.
Licensee's Proposed Alternative to the ASME Code Pursuant to 10 CFR 50.55a(z)(1 ), the licensee requests authorization to utilize the alternative provided in Code Case N-702 in lieu of the requirements of Table IW8-2500-1, Examination Category 8-D, Item Nos. 83.90 and 83.100, for reactor vessel nozzle to vessel welds and nozzle inside radius sections, respectively. These components are identified in Attachment 1 of the licensee's letter dated February 6, 2018, and the licensee confirmed that this alternative will not be used for the feedwater nozzles.
Code Case N-702 allows a 25 percent sampling of the reactor vessel nozzle inner radius section examinations and nozzle-to-vessel weld examinations to be implemented, provided at least one nozzle from each system and nominal pipe size is examined. This alternative also allows a VT [Visual Technique] -1 examination of the nozzle inner radius base metal surfaces to be performed in lieu of the Code-required volumetric examination. NRC staff's position is that if VT-1 examinations are performed in lieu of volumetric examinations then ASME Code Case N-648-1, "Alternative Requirements for Inner Radius Examinations of Class 1 Reactor Vessel Nozzles," should be used with the associated RG 1.147 condition.
For the nozzle-to-vessel welds requiring examination, a volumetric examination will be performed. ASME Code, Section XI, Appendix VIII, 2001 Edition with no Addenda will be used for volumetric examinations as mandated in 10 CFR 50.55a(b)(2)(xv).
Licensee's Basis for Proposed Alternative The performance of nondestructive examination has improved substantially since the examinations of ASME Code, Section XI, Table IWB-2500-1, Examination Category B-D, Item Nos. B3.90 and 83.100, were first required, such that there is now a high reliability of detecting flaws that can challenge the structural integrity of BWR nozzles and their associated welds.
Furthermore, knowledge of improved nondestructive examination capabilities, coupled with fracture mechanics, provides a technical basis to justify reduction of inspections while maintaining safety. This technical basis is provided in BWRVIP-108 and BWRVIP-241.
For any cracks in the nozzle blend radius region, the results of BWRVIP-108 show that the conditional failure probability of the nozzles due to a low temperature overpressure events are very low (<1x1Q-6 for 40 years), even without any ISi. At the nozzle-to-vessel weld, the conditional probability of failure due to the low temperature overpressure event is also very small (<1x1Q-6 for 40 years), with or without any ISi.
3.2 NRC Staff Evaluation 3.2.1 BWRVIP-108, BWRVIP-241, and NRC Requirements The NRC staffs SE for the BWRVIP-241 have plant-specific criteria that must be met for applicants proposing to use Code Case N-702.
In the NRC staff's SE for BWRVIP-241, Section 5.0, "Conditions and Limitations," states that each licensee who plans to request relief from ASME Code, Section XI, requirements for RPV nozzle-to-vessel welds and nozzle inner radii sections may reference the BWRVIP-241 report as the technical basis for the use of Code Case N-702 as an alternative. However, each licensee should demonstrate the plant-specific applicability of the BWRVIP-241 report to its plant in the relief request by demonstrating that the general and nozzle-specific criteria are satisfied.
The BWRVIP-241 documents additional probabilistic fracture mechanics results which support the revision of the five evaluation criteria in BWRVIP-108. Since the objective of BWRVIP-241 is limited to revising the limitations and conditions specified in the SE for the BWRVIP-108 report, it is considered a supplement to BWRVIP-108 and not a replacement. Licensees requesting relief from the ASME Code, Section XI, inspection requirements on the subject RPV nozzles for their plants must demonstrate that the five plant specific criteria are satisfied so that it can be confirmed that BWRVIP-241 report results apply to their plants.
In the NRC staff's SE for BWRVIP-108, it was established that only the recirculation inlet and outlet nozzles need to be assessed since the conditional probability of failure for other nozzles are an order of magnitude lower. It was also established that only the driving force needs to be assessed since the nozzle material fracture toughness related reference temperature for nil ductility transition (RTNor) values used in the probabilistic fracture mechanics analyses were based on data from the entire fleet of BWR reactor pressure vessels, making the probabilistic fracture mechanics analyses bounding with respect to fracture resistance.
The BWRVIP-241 provides additional probabilistic fracture mechanics analyses for the recirculation inlet and outlet nozzles which have the highest driving force among the BWR fleet, to demonstrate that the associated vessel probability of failure during normal operation (the limiting condition) is still consistent with the NRC safety goal; thus, supporting the proposed revision of the five evaluation criteria. The staff's SE for BWRVIP-241 accepted the proposed revision of the five evaluation criteria in BWRVIP-108.
3.2.2 NRC Staff Evaluation of the Licensee Submissions Code Case N-702 states, in part, that it excludes BWR feedwater nozzles and control rod drive (CRD) return line nozzles. In Attachment 2 of the letter dated September 26, 2017, the licensee included the N10 nozzle from the CRD system in its list of components that were applicable to Code Case N-702; specifically, the CRD Nozzle-to-Vessel Weld (ID# 15-315) and the CRD Nozzle Inside Radius Section (ID# 15 315 IRS). The NRC staff concluded that inclusion of the N 10 nozzle in the licensee's submittal was not appropriate based on the exclusion in Code Case N-702.
By email dated January 19, 2018 (ADAMS accession no. ML18022A109), the NRC staff issued a request for additional information, which asked the licensee to justify including the CRD N10 nozzle in its submittal dated September 26, 2017. By letter dated February 6, 2018, the licensee withdrew its request to include the CRD N 10 nozzle in RR-A37. The removal of the N10 CRD nozzle is consistent with the exclusion in Code Case N-702; thus, the NRC staff finds the licensee's response acceptable.
In a letter dated September 26, 2017, the licensee provided its evaluation of the five criteria, including the driving force factors, or ratios, using Fermi 2 RPV and nozzle data, and compared them against the criteria established in the BWRVIP-241. The NRC staff's review and evaluation of each criterion for Fermi 2 are documented below:
Criterion 1 In BWRVIP-241 SE, Criterion 1 limits the maximum RPV heatup/cooldown rate to less than 115 degrees Fahrenheit (°F) per hour. The licensee confirmed that, Surveillance Requirement 3.4.10.1 in Fermi 2 technical specifications limits the RPV heatup/cooldown to less than or equal to 100 °F in any 1-hour period; thus, Criterion 1 is satisfied.
Criteria 2 and 3 - Recirculation inlet nozzles (N2)
In the NRC staff's SE for BWRVIP-241 SE, the ratio for Criterion 2 is required to be less than or equal to 1.15 and for Criterion 3, it is less than or equal to 1.47. The Fermi 2 calculation of Criteria 2 and 3 resulted in a maximum value of 0.89 and 1.229, respectively for the N2 nozzle; thus, the NRC staff finds that Criteria 2 and 3 are satisfied.
Criteria 4 and 5 - Recirculation outlet nozzles (N1)
In the NRC staff's SE for BWRVIP-241, the ratio for Criterion 4 is required to be less than or equal to 1.15 and for Criterion 5, it is less than or equal to 1.59. Fermi 2's calculations for
Criteria 4 and 5 resulted in a maximum value of 1.07 and 1.069 for the N1 nozzle, respectively; thus, the NRC staff finds that Criteria 4 and 5 are satisfied.
Code Case N-702 states that a VT-1 examination may be used in lieu of the volumetric examination for the inner radii sections (i.e., Item No. 83.100, "Nozzle Inside Radius Section").
By letter dated December 8, 2017, the licensee supplemented its September 26, 2017, letter by stating it will use Code Case N-648-1 with the associated RG 1.147 condition, if VT-1 examinations are performed in lieu of volumetric examinations. Thus, the staff finds Fermi 2's use of a VT-1 examination for the nozzle inner radii appropriate.
Based on the licensee's evaluation and plant-specific results for Fermi 2, the NRC staff finds the licensee has adequately addressed the conditions and limitations outlined in Section 5.0 of the BWRVIP-241 SE, and has demonstrated the plant-specific applicability of the BWRVIP-241 report. As such, the staff determined that the inspection of 25 percent of each RPV nozzle type, with the exception of the feedwater nozzles and CRD return nozzles during the third ISi interval for Fermi 2, is acceptable.
4.0 CONCLUSION
The NRC staff reviewed the licensee's evaluation of the five criteria specified in the SE for the BWRVIP-241 report which provides technical bases for Code Case N-702, to examine RPV nozzle-to-vessel welds and nozzle inner radii sections at Fermi 2. As set forth above, the NRC staff determined that the licensee's proposed alternative provides an acceptable level of quality and safety and applies to all requested Fermi 2, RPV nozzles, with the exception of the feedwater nozzles and CRD return nozzles.
Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(1) and has demonstrated that they meet the conditions specified in RG 1.147 for the use of Code Case N-702. Therefore, the NRC authorizes the licensee's proposed alternative to use Code Case N-702 for inspection of nozzle-to-vessel welds and nozzle inner radii sections of RPV nozzles listed in Section 3.1 of this SE for the duration of the third ISi interval which began on May 2, 2009, and is scheduled to end on May 1, 2019.
All other ASME Code, Section XI, requirements for which relief was not specifically requested and approved remain applicable, including third-party review by the Authorized Nuclear lnservice Inspector.
Principal Contributor: On Yee Date of issuance: June 5, 2018
ML18096A614 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DMLR/MVIB NRR/DORL/LPL3/BC NAME SGoetz SRohrer SRuffin DWrona DATE 05/14/18 05/10/18 02/21/18 06/05/18