ML102590141
| ML102590141 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 10/01/2010 |
| From: | Robert Pascarelli Plant Licensing Branch III |
| To: | Jennifer Davis Detroit Edison |
| Chawla M, NRR/DORL, 415-8371 | |
| References | |
| TAC ME3117 | |
| Download: ML102590141 (9) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 1, 2010 Mr. Jack M. Davis Senior Vice President and Chief Nuclear Officer Detroit Edison Company Fermi 2 - 210 NOC 6400 North Dixie Highway Newport, MI 48166 SUB~IECT: RELIEF REQUEST RR-A37 FOR FERMI 2 RE: EVALUATION OF ALTERNATIVE TO REACTOR PRESSURE VESSEL NOZZLE-TO-VESSEL WELDS AND INNER RADIUS EXAMINATIONS (TAC NO. ME3117)
Dear Mr. Davis:
By letter dated January 20, 2010, as supplemented by letter dated August 13, 2010, Detroit Edison (the licensee), submitted Relief Request RR-A37 to use an alternative to American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI inspection requirements regarding examination of certain reactor pressure vessel (RPV) nozzle to-vessel welds and nozzle inner radii at Fermi 2.
The Nuclear Regulatory Commission (NRC) staff has reviewed the submittal and determined that the licensee's proposed alternative, pursuant to Title 10 of the Code of Federal Regulations 50.55a(a)(3)(i), provides an acceptable level of quality and safety and applies to all requested Fermi 2 RPV nozzles, with the exception of the RPV recirculation inlet nozzles, feedwater nozzles, and control rod drive return nozzles. It should be noted that the licensee's request did not include the VT-1 visual examination specified in ASME Code Case N-702, Item Nos. B3.20 and B3.100. The requested duration is the remainder of the third 1O-year interval of the Fermi 2 inservice inspection program 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 Inservice Inspector. The NRC staff review and evaluation is contained in the enclosed safety evaluation.
J. Davis -2 If you have any questions, please contact Mahesh Chawla of my staff at (301) 415-8371.
Sincerely,
~~
Robert J. Pascarelli, Branch Chief Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-341
Enclosure:
Safety Evaluation cc w/encl: Distribution via ListServ
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST NUMBER RR-A37 ALTERNATIVE TO REACTOR PRESSURE VESSEL NOZZLE-TO-VESSEL WELDS AND INNER RADIUS EXAMINATIONS DETROIT EDISON FERMI 2 DOCKET NUMBER 50-341
1.0 INTRODUCTION
By letter dated January 20,2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML100220171), as supplemented by letter dated August 13, 2010 (ADAMS Accession No. ML102280294), Detroit Edison, the licensee for Fermi 2, submitted Relief Request RR-A37 to use an alternative to American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI inspection requirements regarding examination of certain reactor pressure vessel (RPV) nozzle-to-vessel welds and nozzle inner radii at Fermi 2. The proposed alternative is in accordance with ASME Code Case N-702, "Alternative Requirements for Boiling Water Reactor (BWR) Nozzle Inner Radius and Nozzle-to Shell Welds," without using the visual (VT-1) examination specified in the Code Case. The technical basis for ASME Code Case N-702 was documented in an Electric Power Research Institute (EPRI) report for the Boiling Water Reactor Vessel and Internals Project (BWRVIP),
"BWRVIP-108: BWR Vessel and Internals Project, Technical Basis for the Reduction of Inspection Requirements for the Boiling Water Reactor Nozzle-to-Vessel Shell Welds and Nozzle Inner Radil." The BWRVIP-108 report was approved by the U.S. Nuclear Regulatory Commission (NRC) in a safety evaluation (SE) dated December 19, 2007 (ADAMS Accession No. ML073600374).
The December 19, 2007, SE for the BWRVIP-108 report specified plant-specific requirements which must be met for applicants proposing to use this alternative. This submittal intended to demonstrate that the relevant Fermi 2 RPV nozzle-to-vessel welds and their inner radii meet these plant-specific requirements so that Relief Request RR-A37 can be approved.
2.0 REGULATORY EVALUATION
Inservice inspection (lSI) of the ASME Code Class 1,2, and 3 components is performed in accordance with Section XI of the ASME Code and applicable addenda as required by Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g), except where specific relief has been Enclosure
-2 granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Title 10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if: (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Title 10 CFR 50.55a(g)(4) states further that ASME Code Class 1, 2, and 3 components (including supports) must meet the requirements, except design and access provisions and preservice examination requirements, set forth in the ASME Code,Section XI to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) twelve months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The applicable lSI Code of Record for the third 10-year lSI interval for Fermi 2 is the 2001 Edition, 2003 Addenda of ASME Code,Section XI.
For all RPV nozzle-to-vessel shell welds and nozzle inner radii, ASME Code,Section XI requires 100 percent inspection during each 10-year lSI interval. However, ASME Code Case N-702 proposes an alternative which reduces the inspection of RPV nozzle-to-vessel shell welds and nozzle inner radius areas from 100 percent to 25 percent of the nozzles for each nozzle type during each 1O-year interval. As mentioned earlier, the NRC has approved the BWRVIP-108 report, which contains the technical basis supporting ASME Code Case N-702.
The December 19,2007, SE regarding the BWRVIP-108 report specified plant-specific requirements to be satisfied by applicants who propose to use ASME Code Case N-702.
3.0 TECHNICAL EVALUATION
The following plant-specific requirements are specified in the December 19, 2007, SE for the BWRVIP-108 report supporting use of the ASME Code Case N-702:
However, each licensee should demonstrate the plant-specific applicability of the BWRVIP-108 report to their units in the relief request by showing that all the following general and nozzle-specific criteria are satisfied:
(1) the maximum RPV heatup/cooldown rate is limited to less than 115 of/hour; For recirculation inlet nozzles (2) (pr/t)/C RPV < 1.15 p = RPV normal operating pressure, r = RPV inner radius, t = RPV wall thickness, and CRPV = 19332 ... ;
- 3 p = RPV normal operating pressure, ro = nozzle outer radius,
=
rj nozzle inner radius, and
=
CNOZZLE 1637 ... ;
For recirculation outlet nozzles (4) (pr/t)/C RPV < 1.15 p = RPV normal operating pressure,
=
r RPV inner radius, t = RPV wall thickness, and C RPV = 16171 ... ; and (5) [p(ro2 + rj2)/ (r o2 - rj2)]/CNOZZLE < 1.15 p = RPV normal operating pressure, r, = nozzle outer radius, rj = nozzle inner radius, and CNOZZLE = 1977 ....
This plant-specific information was required by the NRC staff to ensure that the probabilistic fracture mechanics (PFM) analysis documented in the BWRVIP-108 report applies to the RPV of the applicant's plant.
3.1 Licensee Evaluation ASME Code Requirement for which Alternative is Requested The licensee requested an alternative to the following requirements of ASME Code,Section XI, 2001 Edition, 2003 Addenda:
ASME Code Class 1 nozzle-to-vessel weld and nozzle inner radii examination requirements are given in Subsection IWB, Table IWB-2500-1, "Examination Category B-O, Full Penetration Welded Nozzles in Vessels - Inspection Program B,"
Item Numbers B3.90, "Nozzle-to-Vessel Welds," and B3.100, "Nozzle Inside Radius Section," respectively. Volumetric examination is required each interval for all nozzles with full penetration welds to the vessel shell (or head) and integrally cast nozzles. All of the nozzle assemblies identified are made with full penetration welds.
Component(s) for which Alternative is Requested ASME Code Class: 1 Examination Category: B-O, Full Penetration Welded Nozzles in Vessels Item Number: B3.90 (nozzle-to-vessel welds) and B3.1 00 (nozzle inner radius sections)
- 4
Description:
See Attachment 2 to the RR-A37[1l enclosure to the licensee's January 20, 2010 letter
[The RPV recirculation inlet nozzles, feedwater nozzles, and control rod drive (CRD) return nozzles are not included. Exclusion of the unit's cut and capped CRD return line nozzle is discussed below.]
In a request for additional information (RAI) transmitted by an email from Mr. Mahesh Chawla to Mr. Alan Hassoun dated April 27, 2010, the NRC staff requested additional information for Relief Request RR-A37 related to the CRD return nozzle which has been cut and capped at Fermi 2.
In response to this RAI, Detroit Edison withdrew the request to include the capped CRD return nozzle in Relief Request RR-A37.
Licensee's Proposed Alternative to the ASME Code Pursuant to 10 CFR 50.55a(a)(3)(i), Detroit Edison requested authorization to utilize the alternative requirements of ASME Code Case N-702 in lieu of the requirements of Table IWB 2500-1, Examination Category B-D, Item Numbers B3.90, and B3.100 for reactor vessel nozzle to-shell welds and nozzle inside radius sections. Detroit Edison intends to apply the alternative sample population criteria provided in ASME Code Case N-702 using the BWRVIP-108 report as the technical basis to reduce the ASME Code,Section XI requirements for RPV nozzle-to vessel shell welds and nozzle inner radius selections. These alternative requirements will not be utilized for the feedwater nozzles, the recirculation inlet nozzles or the CRD return nozzle which has been cut and capped at Fermi 2.
This alternative allows a 25 percent sampling of the reactor vessel nozzle inner radius section examinations and nozzle-to-shell 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-1 examination of the nozzle inner radius base metal surfaces to be performed in lieu of the ASME Code required volumetric examination. For the nozzle-to-shell welds requiring examination, a volumetric examination will be performed. ASME 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 Bases for Alternative The BWRVIP-108 report provides the technical basis for the reduction of the nozzle-to-shell welds and nozzle blend radii from 100 percent to 25 percent of the nozzles every 10 years. This EPRI report received an NRC SE dated December 19, 2007. In the SER, Section 5.0 "Plant Specific Applicability" indicates that each licensee who plans to request relief from the ASME Code,Section XI requirements for RPV nozzle-to-vessel shell welds and nozzle inner radius sections may reference BWRVIP-1 08 report as the technical basis for the use of the alternatives presented herein. However, each licensee should demonstrate the plant specific applicability of the BWRVIP-108 report to its units in the relief request by showing that all the general and nozzle-specific criteria addressed below are satisfied (reference Enclosure RR-A37):
[1] This refers to Attachment 2 to the RR-A37 enclosure to the licensee's January 20,2010, submittal, which shows a complete list of applicable nozzles. This Attachment is not included in this SE.
-5 Criterion 1: the maximum RPV heatup/cooldown rate is less than 1150 F/hour, (1) Per Fermi 2 Technical Specification TS SR 3.4.10.1, the RPV heatup/cooldown is limited to less than or equal to115° F any 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> period. This criterion is met.
Criteria 2 and 3: for recirculation inlet nozzles, (2) (pr/t)/C RPV =0.89 < 1.15 Criteria 4 and 5: for recirculation outlet nozzles, (4) (pr/t)/C RPV =1.07 < 1.15 Based upon the above information, all RPV nozzle-to-vessel shell welds and nozzle inner radius sections, with the exception of the recirculation inlet nozzles, meet the criteria and therefore are applicable. Since the recirculation inlet nozzles do not meet the criteria, the alternative requirements will not be applied to those nozzles. Additionally, as stated earlier, this alternative will not be applied to the feedwater nozzles and CRD return line nozzles.
3.2 Staff Evaluation The December 19, 2007, SE for the BWRVIP-108 report specified five plant-specific criteria that licensees must meet to demonstrate that the BWRVIP-1 08 report results apply to their plants.
The five criteria are related to the driving force of the PFM analyses for the recirculation inlet and outlet nozzles. It was stated in the December 19, 2007, SE that the nozzle material fracture toughness-related reference temperature (RT NDT) used in the PFM analyses was based on data from the entire fleet of BWR RPVs. Therefore, the BWRVIP-108 report PFM analyses are bounding with respect to fracture resistance, and only the driving force of the underlying PFM analyses needs to be evaluated. It was also stated in the December 19, 2007, SE that, except for the RPV heatup/cooldown rate, the plant-specific criteria are for the recirculation inlet and outlet nozzles only because the probabilities of failure, P(FIE)s, for other nozzles are an order of magnitude lower. The plant-specific heatup/cooldown rate that the staff established in Criterion 1 considers the rate under the plant's normal operating condition, which is limiting.
Events with excursions of heatup/cooldown rates exceeding 1150 F/hour are considered as transients. According to the December 19, 2007, SE, the PFM results with a very severe low temperature overpressure transient is not limiting, largely because the event frequency for that transient is 1x10-3 as opposed to 1.0 for the normal operating condition.
The licensee provided in the submittal Detroit Edison's plant-specific data for the Fermi 2 RPV and its evaluation of the five driving force factors, or ratios, against the criteria established in the December 19, 2007, SE. The NRC staff verified the licensee's evaluation, which indicated that, except for the second criterion (related to the recirculation inlet nozzles), all other criteria are satisfied. As a result, the reduced inspection requirements in accordance with ASME Code Case N-702 do not apply to the Fermi 2 RPV recirculation inlet nozzles. The NRC staff agrees with the licensee's decision to exclude the recirculation inlet nozzles from the scope of this
-6 request based upon the licensee's evaluation. Considering that the driving force factor for the recirculation inlet nozzles (1.23) is only moderately higher than the plant-specific criterion (1.15) and the P(FIE)s for other RPV nozzles are an order of magnitude lower than the recirculation inlet nozzles, the NRC staff concluded that the licensee's proposed alternative for all Fermi 2 RPV nozzles included in this application (see Section 3.1 of this SE) provides an acceptable level of quality and safety. It should be noted that RPV feedwater nozzles and CRD return line nozzles (CRD return nozzles which have been cut and capped are also excluded) are outside the scope of ASME Code Case N-702 and are also outside the scope of this application.
ASME Code Case N-702 permits a VT-1 visual examination in lieu of volumetric examination for Item Nos. 83.20 and 83.100 which includes the visual examination of the nozzle inner radius without performing a sensitivity demonstration of detecting a 1-mil width wire or crack. This is not consistent with the NRC position established in Regulation Guide 1.147 regarding ASME Code Case N-648-1. However, since the licensee stated in the submittal that for the nozzle-to shell welds (Item No. 83.100) requiring examination, a volumetric examination will be performed, the inconsistency between ASME Code Case N-702 and the NRC position regarding VT-1 is not an issue in this application.
4.0 CONCLUSION
The NRC staff has reviewed the submittal regarding the licensee's evaluation of the five plant specific criteria specified in the December 19,2007, SE for the 8WRVIP-108 report, which provides technical bases for use of ASME Code Case N-702, to examine RPV nozzle-to-vessel welds and nozzle inner radii at Fermi 2. 8ased on the evaluation in Section 3.2 of this SE, the NRC staff determined that the licensee's proposed alternative, pursuant to 10 CFR 50.55a(a)(3)(i), provides an acceptable level of quality and safety and applies to all requested Fermi 2 RPV nozzles, with the exception of the RPV recirculation inlet nozzles, feedwater nozzles, and CRD return nozzles. It should be noted that the licensee's request did not include the VT-1 visual examination specified in ASME Code Case N-702, Item Nos. 83.20 and 83.100.
The requested duration is the remainder of the third 1O-year interval of the Fermi 2 lSI program which began on May 2, 2009 and is scheduled to end 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 Inservice Inspector.
Principal Contributor: Ed Andruszkiewicz, I'JRR Date: October 1, 2010
J. Davis -2 If you have any questions, please contact Mahesh Chawla of my staff at (301) 415-8371.
Sincerely, IRAJ Robert J. Pascarelli, Branch Chief Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-341
Enclosure:
Safety Evaluation cc w/encl: Distribution via ListServ DISTRIBUTION:
PUBLIC LPL3-1 RlF RidsNrrDorlLpl3-1 Resource RidsOgcRp Resource RidsAcrsAcnw_MailCTR Resource RidsNrrPMFermi2 Resource EAndruszkiewicz, NRR RidsNrrDirsltsb Resource RidsNrrLABTully Resource SDinsmore, NRR RidsNrrDorlDpr Resource RidsRgn3MailCenter Resource DMerzke, EDO Rill ADAMS Accession Number" ML102590141 OFFICE NRRlLPL3-1/PM NRRlLPL3-1/LA NRRlCVIB/BC NRRlLPL3-1/BC NAME MChawla BTully MMitchell RPascarelli DATE 09/28/10 09/28/10 09/28/10 10/01/10 OFFICIAL RECORD COPY