RS-09-019, Third 10-Year Inservice Inspection Interval, Relief Request 13R-04, Request for Relief from 10CFR50.55a(g)(6)(ii)(E), Reactor Coolant Pressure Boundary Examination Scheduling Requirements in Accordance with 10CFR50.55a(a)(3)(i)
| ML090370190 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 02/05/2009 |
| From: | Simpson P Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RS-09-019 | |
| Download: ML090370190 (10) | |
Text
Exelon Nuclear www.exeloncorp.com 4300 Winfield Road Warrenville, IL 60555 RS-09-019 February 5, 2009 U. S. Nuclear Regulatory Commission ATTN : Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. 50-456 and 50-457 EGC requests authorization of this relief request by March 30, 2009, in support of the Braidwood Unit 1 spring refueling outage (A1 R14).
Exel6n
Subject:
Third 10-Year Inservice Inspection Interval, Relief Request 13R-04, Request for Relief from 10 CFR 50.55a(g)(6)(ii)(E), Reactor Coolant Pressure Boundary Examination Scheduling Requirements in accordance with 10 CFR 50.55a(a)(3)(i)
Nuclear 10 CFR 50.55a In accordance with 10 CFR 50.55a, "Codes and standards," paragraph (3)(i), Exelon Generation Company, LLC, (EGC) is requesting NRC approval of the following request for the third 10-year interval inservice inspection (ISI) program for the Braidwood Station, Units 1 and 2. EGC is requesting authorization to use augmented NDE examinations performed during previous refueling outages as an alternative to the reactor vessel BMI penetrations examination program required in accordance with 10 CFR 50.55a(g)(6)(ii)(E), Footnote 1. The details of this request are enclosed.
In September 2008, the NRC mandated, through a revision to 10 CFR 50.55a, the use of Code Case N-722, as modified by 10 CFR 50.55a(g)(6)(ii)(E)(1) through (4). NEI, on behalf of EGC, has discussed with the NRC implementation of Code Case N-729-1 and Code Case N-722. On or around January 22, 2009, EGC became aware that volumetric examinations conducted by Braidwood Station during the last refueling outages in October 2007 (Unit 1, A1 R13) and April 2008 (Unit 2, A2R13) could not be credited in lieu of the bare-metal visual (BMV) examinations required by Note 1 to 10 CFR 50.55a(g)(6)(ii)(E) to be performed during each unit's next refueling outage after January 1, 2009 (i.e., A1 R14 for Unit 1 (spring 2009) and A2R14 for Unit 2 (fall 2009)). Therefore, EGC is submitting this relief request.
February 5, 2009 U. S. Nuclear Regulatory Commission Page 2 There are no regulatory commitments contained in this letter.
If you have any questions concerning this letter, please contact Ms. Lisa A. Schofield at (630) 657-2815.
Rp§pectfully, Patrick R. Simpson Manager - Licensing r
Attachments :
1 : Braidwood Station 10 CFR 50.55a Relief Request 13R-04 2: Bottom-Mounted Instrument Examination Typical Area of Examination Coverage
ATTACHMENT 1 Braidwood Station 10 CFR 50.55a Relief Request 13R-04
Code Class:
Reference:
Examination Category :
Item Number :
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Description:==
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ISl Program Plan Braidwood Station Units 1 & 2, Third Interval ATTACHMENT 1 10 CFR 50.55a RELIEF REQUEST 13R-01 (Page 1 of 5)
Request for Relief from 10 CFR 50.55a(g)(6)(ii)(E)
Reactor Coolant Pressure Boundary Examination Scheduling Requirements in accordance with 10 CFR 50.55a(a)(3)(i)
ASME CODE COMPONENTS AFFECTED :
2.0 APPLICABLE CODE EDITION AND ADDENDA:
4.0 REASON FOR REQUEST:
1 ASME Code Case N-722 and 10 CFR 50.55a(g)(6)(ii)(E)
Class 1 PWR Components Containing Alloy 600/82/182 B15.80 RPV Bottom-Mounted Instrument (BMI) Penetrations 58 Penetrations per Unit 1 RV-02 (Unit 1), 2RV-02 (Unit 2)
The Braidwood Station Third Interval Inservice Inspection (ISI) program is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV)
Code,Section XI, 2001 Edition through the 2003 Addenda.
3.0 APPLICABLE CODE REQUIREMENT:
ASME Code Case N-722, "Additional Examinations for PWR Pressure Retaining Welds in Class 1 Components Fabricated With Alloy 600/82/182 MaterialsSection XI Division 1 " as modified by paragraphs 10 CFR 50.55a(g)(6)(ii)(E)(1) through (4).
Footnote 1 to paragraph (g)(6)(ii)(E) in 10 CFR 50.55a states in part,
... inspections conducted every other refueling outage, the initial inspection shall be performed at the next refueling outage after January 1, 2009.
Pursuant to 10 CFR 50.55a(a)(3)(i), relief is requested on the basis that the proposed alternative will provide an acceptable level of quality and safety.
In order to mandate the implementation of Code Case N-722, the NRC amended 10 CFR 50.55a to incorporate ASME Code Case N-722 by reference in the final rule published in the Federal Register Notice 73 FR 52730, "10 CFR Part 50 Industry Codes and Standards; Amended Requirements," dated September 10, 2008. The NRC required implementation of Code Case N-722 because the NRC concluded from a safety perspective that these inspections are necessary to ensure the integrity of components fabricated from Alloy 600/82/182 materials.
As noted in revised 10 CFR 50.55a(g)(6)(ii)(E) :
(E) Reactor coolant pressure boundary visual inspections.'
(1) All licensees of pressurized water reactors shall augment their inservice inspection program by implementing ASME Code Case N-722 subject to the conditions specified in paragraphs (g)(6)(ii)(E) (2) through (4) of this section.
Footnotes :
ISI Program Plan Braidwood Station Units 1 & 2, Third Interval ATTACHMENT 1 10 CFR 50.55a RELIEF REQUEST 13R-01 (Page 2 of 5)
' For inspections to be conducted every refueling outage and inspections conducted every other refueling outage, the initial inspection shall be performed at the next refueling outage after January 1, 2009.
Code Case N-722 categorizes the reactor pressure vessel (RPV) BMI penetrations as Item 1315.80, which requires a "Visual, VE" (VE) examination to be performed at a frequency of every other refueling outage.
Note 5 of Table 1 in Code Case N-722 indicates that "[a]n ultrasonic examination, performed from the component inside or outside surface in accordance with the requirements of Table IWB-2500-1 and Appendix Vill (1995 Edition with the 1996 Addenda or later) shall be acceptable in lieu of the VE requirement of this table." This note is applicable for all of the examination items in the table. As there are no volumetric requirements for examination of the BMI penetration welds in Table IWB-2500-1 (volumetric examinations specified in Table IWB-2500-1 are only applicable to NPS 4 and larger), there are no Appendix Vlll requirements to be followed for BMI volumetric examinations. Therefore, any volumetric examination of the BMI penetrations cannot meet the literal requirements of this note.
Braidwood Station, Units 1 and 2, requests relief from the requirement of Footnote 1 to 10 CFR 50.55a(g)(6)(ii)(E), which would require the performance of a WE" bare-metal visual (BMV) examination of the RPV BMI penetrations during the next refueling outage after January 1, 2009 (i.e., A1 R14 for Unit 1 (spring 2009) and A2R14 for Unit 2 (fall 2009)).
5.0 PROPOSED ALTERNATIVE AND BASIS FOR USE:
Braidwood Station, Units 1 and 2, proposes to take credit for ultrasonic and eddy current testing performed during the last refueling outages in October 2007 (Unit 1, A1 R13) and April 2008 (Unit 2, A2R13) in lieu of the WE" BMV examinations required by Code Case N-722 and Footnote 1 to 10 CFR 50.55a(g)(6)(ii)(E) to be performed during each unit's next refueling outage after January 1, 2009.
BMV examinations would occur at the required examination frequency for Unit 1 in refueling outage A1 R15 (fall 2010) and for Unit 2 in refueling outage A2R15 (spring 2011).
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Background===
ISI Program Plan Braidwood Station Units 1 & 2, Third Interval ATTACHMENT 1 10 CFR 50.55a RELIEF REQUEST 13R-01 (Page 3 of 5)
After the initial discovery of BMI leakage at South Texas Project (STP) Unit 1, the NRC issued Bulletin 2003-02 (Reference 7.1) on August 21, 2003. The Bulletin requested that addressees provide the NRC with information related to inspections performed to verify the integrity of RPV lower head penetrations, as well as, to provide a description of the RPV lower head penetration program that would be implemented at respective plants during the next, and subsequent, refueling outages.
By letter dated September 22, 2003 (Reference 7.2), EGC provided its response to Bulletin 2003-02. EGC committed to perform a BMV of the RPV lower head surface, and on 100 percent of all RPV lower head penetrations for Braidwood Station. For Braidwood Station, EGC indicated that the extent, and frequency of subsequent visual examinations of the RPV lower head penetrations for subsequent outages, would depend on the appropriate NRC and industry guidance, as well as EGC procedure ER-AP-331-1001, "Boric Acid Corrosion Control (BACC) Inspection Locations, Implementation and Inspection Guidelines." Initially, ER-AP-331-1001 included a requirement to perform the BMV every third outage. BMV examinations were completed during the A1 R11 (October 2004) and A2R10 (November 2003) outages with no evidence of through-wall leakage noted on either unit. NRC acknowledged that Braidwood Station met the reporting requirements of the Bulletin (References 7.3 and 7.4, respectively). Until publication of 10 CFR 50.55a(g)(6)(ii)(E) in September 2008, formal guidance for the type and frequency of subsequent BMI examinations had not been provided by either NRC or industry groups.
Although not required by ASME Section XI or regulation, Braidwood Station proactively performed non-visual NDE (time of flight ultrasonic (UT) and eddy current) examinations of the BMI penetrations in anticipation of future industry or NRC requirements. These inspections were completed in conjunction with the ten-year RPV inservice inspection.
For Braidwood Station, Unit 1, examination of all 58 penetrations was completed during the A1 R13 refueling outage in October 2007 and for Braidwood Station, Unit 2, examination of all 58 BMI penetrations was completed during the A2R13 refueling outage in May 2008. Automated ultrasonic and eddy current examinations of all the Braidwood Station, Units 1 and 2 BMI penetration tubes revealed no recordable UT or eddy current indications.
NDE Methods The BMI examinations were completed using vendor procedures demonstrated through the Electric Power Research Institute (EPRI) Materials Reliability Project (MRP). The BMI examination demonstration process addressed examinations for primary water stress corrosion cracking (PWSCC) flaws initiating on the inside diameter (ID) and outside diameter (OD) surfaces of the BMI penetration base material (tube), and PWSCC flaws in the J-groove attachment weld. The CRDM head penetration demonstration program was used as the basis for the BMI demonstration program. The MRP evaluated the level of performance of examination processes, procedures, and equipment for detecting and sizing flaws located in Alloy 600 BMI. The procedures used
ISI Program Plan Braidwood Station Units 1 & 2, Third Interval ATTACHMENT 1 10 CFR 50.55a RELIEF REQUEST 13R-01 (Page 4 of 5) at Braidwood Station were initially demonstrated through the MRP protocol using the EPRI NDE Center as a third party reviewer to monitor demonstration activities. Based on initial demonstration results, the vendor procedures were refined and enhanced to incorporate lessons learned along with utility and EPRI comments. A brief discussion of the MRP's activities associated with BMI is contained in Section 7 of NUREG-1863 (Reference 7.5). As discussed in NUREG-1863, for the Westinghouse 3-loop/4-loop design BMI, NDE techniques were demonstrated and successfully detected all mock-up flaws. Attachment 2 shows the typical area of examination coverage associated with the NDE examinations performed at Braidwood Station.
Unlike a VE examination, which relies on the presence of through-wall leakage to determine acceptance, demonstrated UT and eddy current NDE methods for identifying any potential flaws in the BMI penetrations prior to through-wall leakage occurring were used at Braidwood Station during the last refueling outage.
The results and conclusions of the evaluation performed in NUREG-1863, combined with the results of the non-visual NDE completed during the recent ten-year ISI examinations, support the conclusion that these examinations are equivalent (if not superior) to a VE examination.
In addition to the non-visual NDE examinations completed, visual examinations of the lower head mirror insulation were performed during ascending Mode 3 walk downs with no evidence of pressure boundary leakage observed.
The ultrasonic and eddy current testing performed during the last outages at Braidwood Station, Units 1 and 2, provide adequate assurance that no indications that would lead to through-wall leakage exist. There were no recordable indications requiring disposition noted during the previous NDE examinations on either Braidwood Unit. Performance of a BMV examination of the BMI penetrations will result in an additional dose of 200 mRem and a cost of $50K for each unit's inspection without any additional safety benefit over the ultrasonic and eddy current testing previously performed.
6.0 DURATION OF PROPOSED ALTERNATIVE:
Relief from immediate implementation of Code Case N-722 for Item 1315.80 components is requested until the A1 R15 and A2R15 refueling outages (fall 2010 and spring 2011, respectively).
7.0 REFERENCES
ISI Program Plan Braidwood Station Units ) & 2, Third Interval ATTACHMENT 1 10 CFR 50.55& RELIEF REQUEST 13R-01 (Page 5 of 5) 7.1.
NRC Bulletin 2003-02, "Leakage from Reactor Pressure Vessel Lower Head Penetrations and Reactor Coolant Pressure Boundary Integrity" 7.2.
Letter from K. R. Jury (EGC) to USNRC, "Thirty-Day Response to NRC Bulletin 2003-02, 'Leakage from Reactor Pressure Vessel Lower Head Penetrations and Reactor Coolant Pressure Boundary Integrity,"' dated September 22, 2003 (ADAMS Accession ML032691399) 7.3.
Letter from G. F. Dick (NRC) to C. M. Crane (EGC), "Braidwood Station, Unit 1 -
Response to Nuclear Regulatory Commission Bulletin 2003-02, 'Leakage From Reactor Pressure Vessel Lower Head Penetrations and Reactor Coolant Pressure Boundary Integrity' (TAC No. MC0523)," dated April 8, 2005 (ADAMS Accession ML050560043) 7.4.
Letter from G. F. Dick (NRC) to C. M. Crane (EGC), "Braidwood Station, Unit 2 -
Response to Nuclear Regulatory Commission Bulletin 2003-02, 'Leakage From Reactor Pressure Vessel Lower Head Penetrations and Reactor Coolant Pressure Boundary Integrity' (TAC No. MC0524)," dated January 31, 2005 (ADAMS Accession ML050030255) 7.5.
NUREG-1863, "Review of Responses to NRC Bulletin 2003-02 Leakage from Reactor Pressure Vessel Lower Head Penetrations and Reactor Coolant Pressure Boundary Integrity," Published September 2006 (ADAMS Accession ML062970288)
ATTACHMENT 2 Bottom-Mounted Instrument Examination Typical Area of Examination Coverage
ATTACHMENT 2 Bottom-Mounted Instrument Examination Typical Area of Examination Coverage (Page 1 of 1)
ISl Program Plan Braidwood Station Units 1 & 2, Third interval T n m O 5'a :6 14 4
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