CP-201200157, Response to Request for Additional Information for Relief Request No. A-1
| ML12082A017 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 03/08/2012 |
| From: | Flores R, Madden F Luminant Generation Co, Luminant Power |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CP-201200157, TAC ME6827, TXX-12023 | |
| Download: ML12082A017 (11) | |
Text
Rafael Flores Luminant Power Senior Vice President P 0 Box 1002 M & Chief Nuclear Officer 6322 North FM 56 Rafael.Flores@Luminant.com Glen Rose, TX 76043 Luminant 2548975550 C 817 559 0403 F 254 897 6652 CP-201200157 Ref. # 10CFR50.55a Log # TXX-12023 March 8, 2012 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK NUCLEAR POWER PLANT DOCKET NO. 50-445 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR RELIEF REQUEST NO. A-1 (TAC NO. ME6827)
REFERENCES:
- 1. Letter logged TXX-11038 dated August 2, 2011 from Rafael Flores to the NRC submitting Relief Request No. A-1 for the Unit 1 Third Interval Inservice Inspection for Application of an Alternative to the ASME Boiler and Pressure Vessel Code Section XI Examination Requirements for Class I and 2 Piping Welds (Third Interval Start Date: August 13, 2010).
- 2. Email dated February 14, 2012 from Balwant Singal of the NRC to Timothy Hope of Luminant Power requesting additional information regarding Relief Request No. A TAC ME6827.
Dear Sir or Madam:
Per reference 1, Luminant Generation Company LLC (Luminant Power) previously submitted a request for relief for application of an alternative to the American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel Code Section XI examination requirements for Class 1 and 2 piping welds.
Per reference 2, the NRC provided a request for additional information regarding the subject relief request.
Luminant Power has provided the information requested per reference 2 in the Attachment 1 and 2 to this letter. Attachment 3 provides a revised table of "CPNPP Unit I - Inspection Location Selection Comparison Between Original Approved and Updated RI-ISI Programs by Risk Category" that was originally included in reference 1.
This communication contains no new commitment regarding Comanche Peak Unit 1.
Should you have any questions, please contact Mr. Jack Hicks at (254) 897-6725.
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway
- Comanche Peak - Diablo Canyon
- Palo Verde - San Onofre
- South Texas Project - Wolf Creek
U. S. Nuclear Regulatory Commission TXX-12023 Page 2 of 2 Sincerely, Luminant Generation Company LLC Rafael Flores By: / *"*,L 24 Fred W. Madden Director, Oversight & Regulatory Affairs Response to Request for Additional Information for Relief Request A-1 Summary of Changes to PRA Model Update to Table on Inspection Location Comparison c- E. E. Collins, Region IV Luis Ponce B. K. Singal, NRR Environmental & Consumer Safety Section Resident Inspectors, Comanche Peak Texas Department of State Health Services Jack Ballard, ANII, Comanche Peak 1100 West 49th Street Austin, Texas 78756-3189 to TXX-12023 Page 1 of 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR RELIEF REQUEST NUMBER A-1 FOR THE UNIT 1 THIRD 10 YEAR IS1 INTERVAL (THIRD INTERVAL START DATE: AUGUST 13, 2010) (TAC NO. ME6827)
The following questions were provided to Luminant Power in the email dated February 14, 2012, from Balwant Singal of the NRC to Timothy Hope of Luminant Power (reference 2) requesting additional information regarding Relief Request Nos. A-i:
NRC Question 1:
- 1. Table titled "CPNPP Unit 1 - Inspection Location Selection Comparison Between Original Approved and Updated RI-ISI Programs by Risk Category" in Attachment to the letter dated August 2, 2011 shows numbers of deleted and added welds for the proposed third 10-year interval RI-ISI program as compared to the original (i.e., the second 10-year interval) RI-ISI program. The NRC staff notes that items 2, 3, and 4 in section titled "Proposed Alternative and Basis for Use" of RR A-i, briefly discussed changes in risk rank and consequence rank of particular piping segments during RI-ISI program updating in 2005, 2007, and 2009.
- a. Please explain and provide technical reason for any changes in risk rank and consequence rank of the added or deleted welds in the table.
Luminant Power's Response to Question la:
Welds were added based on their Consequence Rank and Risk Rank in accordance with the approved process utilized in the originalsubmittal. Since they were not in the original submittal, there is no change in Risk Rank or Consequence Rank other than their creation. Deleted welds were deletedfrom the Risk Ranking. Other changes to weld count distributionwere as a result of Risk Rank changes as explained below.
- b. Please explain and provide technical reason(s) for changing risk rank and consequence rank of each segment or weld in items 2, 3, and 4; and provide associated piping system for each segment or weld.
Luminant Power's Response to Question 1b:
The technical basisfor the Risk Rank is the combination of Consequence Rank and DegradationMechanism (DM)
Rank, as derived in accordance with the Risk Matrix described in EPRI TR-1 12657 Rev. B-A (see Attachment 2).
The change in Risk Rank in each case was attributedto the change in associated Consequence Rank. The changes in Consequence Rank resultedfrom re-quantificationof consequences associatedwith each revised PRA model. A summary of changes to the PRA model was provided in the PRA Model Capabilitysection of the submittal.
However, to further clarify those changes a summary of changes to the PRA model is provided in Attachment 2 that identifies the changes to each of the three (3) model revisions identified in the submittal. A list of Consequence Segments with their associated Risk Segments and Systems is also included in Attachment 2. Note that in some cases a Consequence Segment changed Consequence Rank in more than one PRA revision. In those cases, the resultantConsequence Rank at the beginning of Interval 3 is used in determiningfinal Risk Rank.
Attachment I to TXX-12023 Page 2 of 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR RELIEF REQUEST NUMBER A-1 FOR THE UNIT 1 THIRD 10 YEAR IS1 INTERVAL (THIRD INTERVAL START DATE: AUGUST 13,2010) (TAC NO. ME6827)
NRC Question 2:
- 2. The second to last paragraph in section titled "Proposed Alternative and Basis for Use" of RR A-1 reads, "The original program represented a reduction of 9.73E-09 in regards to CDF [core damage frequency] and 3.91E-09 in regards to LERF [large, early release frequency], while the revised program represents a reduction of 8.3E-09 in regards to CDF and 1.06E-09 in regards to LERF."
The NRC staff notes that on pages 13 and 27 of the original relief request dated February 15, 2001, (ADAMS Accession No. ML010520269), the above calculated reductions in regard to CDF and LERF were cited for CPNPP, Unit 2.
- a. Please clarify whether a reduction of 9.73E-09 in regards to CDF and 3.91E-09 in regards to LERF belong to CPNPP, Unit 1, or revise the request to reflect the correct reductions in regard to CDF and LERF.
Luminant Power's Response to Question 2a:
The values attributableto CPNPPUnit 2 were listed bny typographicalerror. The correct valuesfor the original CPNPPUnit I program are a reduction of 9.27E-09 in regardsto CDF and a reduction of 3.74E-09 in regards to LERF.
No. 2.a were incorrectly referenced in the submittal, please explain impacts of the correct reduction in regard to CDF and LERF for CPNPP, Unit 1, to risk analysis.
Luminant Power's Response to Question 2b:
The risk reduction values for the original CPNPP Unit I program in regards to CDF and in regards to LERF were provided for information only and have no impact on the fact that the revised program represents a risk reduction when compared to the last deterministic Section XI inspection program.
- c. Please confirm that in the revised RI-ISI program (i.e., RR A-i), a reduction of 8.3E-09 in regard to CDF and 1.06E-09 in regard to LERF were obtained correctly.
Luminant Power's Response to Question 2c:
The Risk Inpact Analysis for the revised CPNPP Unit 1 RI-ISI program was reviewed and the reductions of 8.3E-09 in regard to CDFand 1.06E-09 in regard to LERF were obtained correctly.
Attachment I to TXX-12023 Page 3 of 3 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR RELIEF REQUEST NUMBER A-1 FOR THE UNIT 1 THIRD 10 YEAR IS1 INTERVAL (THIRD INTERVAL START DATE: AUGUST 13, 2010) (TAC NO. ME6827)
NRC Question 3:
Please identify any augmented inspection programs subsumed in the proposed third 10-year interval RI-ISI program and discuss the reason(s) for any changes. Examples of augmented programs for piping inspections include service water integrity program (Generic Letter (GL) 89-13), flow accelerated corrosion (FAC) (GL 89-08), thermal fatigue (Bulletins (BL) 88-08 and BL 88-11 and Information Notice (IN) 93-020), and stress corrosion cracking (BL 79-17).
Luminant Power's Response to Question 3:
No augmented programs were subsumed in the proposed third 10-year interval RI-ISI program.
NRC Question 4:
In the NRC rulemaking dated June 21, 2011, Title 10 of the Code of FederalRegulations (10 CFR),
Paragraph 50.55a(g)(6)(ii)(F) describes examination requirements for American Society of Mechanical Engineers (ASME) Code Class 1 piping and nozzle dissimilar metal (DM) butt welds. Pursuant to 10 CFR 50.55a(g)(6)(ii)(F)(1), licensees shall implement the requirements of ASME Code Case N-770-1, "Alternative Examination Requirements and Acceptance Standards for Class 1 PWR Piping and Vessel Nozzle Butt Welds Fabricated with UNS N06082 or UNS W86182 Weld Filler Material with or without Application of Listed Mitigation Activities," subject to the conditions specified in paragraphs (g)(6)(ii)(F)(2) through (g)(6)(ii)(F)(10) of 10 CFR 50.55a, by the first refueling outage after August 22, 2011. On July 12, 2011 the NRC staff held a public meeting to discuss the requirements of 10 CFR 50.55a(g)(6)(ii)(F) and the implementation of ASME Code Case N-770-1 (Reference ADAMS Accession No. ML112240818).
Please describe how the proposed CPNPP, Unit 1, RI-ISI program alternative for the third 10-year ISI interval will address the requirements of 10 CFR 50.55a(g)(6)(ii)(F) and the ASME Code Case N-770-1 implementation.
Luminant Power's Response to Question 4 ASME Code Case N-770-1 will be implemented in accordancewith the requirements of 10 CFR 50.55a(g)(6)(ii)(F) as a separateprogram. The RI-ISI program alternativefor the third 10-year ISI interval will have no impact on the implementation of requirementsfor Code Case N-770-1. The Code Case N-770-1 butt welds are included in the RI-ISI weld count, with some of the welds counted in the RI-ISI Program as elements selected to be examined during the third intervalfor certain risk categories and rankings.
to TXX-12023 Page 1 of 4 Summary of Changes to PRA Model A summary of changes to the PRA modelfor the revisions associated with the Third Interval RI-ISI Update submittal is provided below. The changes in Consequence Rankfor each Consequence Segment associated with each model revision is provided in the summary table that follows.
Revision 3D to the CPNPP PRA Model of Record incorporatedUnit I and Unit 2 power up-rates. This plant change required the creation of unit specific databasesdue to slight differences in core uncover! times. These differences affect the values of the LOOP recovery events appliedfollowing quantification of thefault tree.
Revision 3C to the CPNPPPRA Model of Record incorporatedchanges to the model file associated with the Unit I steam generatorreplacement (SGR) project. This change resulted in an update to the plant specific thermal hydraulic analyses to reflect the SGR and Emergency Operating Procedure(EOP) revisions, and created a unit difference in the PRA fault tree model. The steam generatorreplacementproject also impacted the rule base recoveryfile, Feed and Bleed HRA values and the databasefiles.
Revision 3B to the CPNPPPRA Model of Record were minor in nature and were associated with changes made to system models to address peer review comments and additionalmodel detail. Changes were also made to the software controlfiles based on an update to the EPRI software (PRAQuant) used to quantify the PRA model.
to TXX-12023 Page 2 of 4 Summary of Changes to PRA Model RISK MATRIX IN ACCORDANCE WITH EPRI TR-112657 REV. B-A Risk Rank Consequence Category High: Cat 1, 2, & 3 Medium: Cat. 4 & 5 None Low Medium High Low: Cat. 6 & 7 LOW MEDIUM HIGH HIGH High (Cat. 7) (Cat.5) (Cat. 3) (Cat.1)
Failure Potential (Mediu i LOW LOW MEDIUM HIGH (Degradation (Cat. 7) (Cat.6) (Cat. 5) (Cat.2)
Mechanism Rank)
Low LOW LOW LOW MEDIUM (Cat. 7) (Cat.7) (Cat. 6) (Cat. 4)
Attachment 2 to TXX-12023 Page 3 of 4 Summary of Changes to PRA Model CONSEQUENCE SEGMENTS WITH THEIR ASSOCIATED RISK SEGMENTS AND SYSTEMS Consequence Consequence Rank Associated Risk Segments Segment PRA Rev 3B PRA Rev 3C PRA Rev 3D Rank at Risk DMs DM Risk Risk System 1-ACC-03A Medium to High High SIS-015 None Low 4 Medium 3SIS SIS-016 None Low 4 Medium 3SIS 1-ACC-03B Medium to High High SIS-017 None Low 4 Medium 3SIS 1-CT-03A Medium to High High CSS-007 None Low 4 Medium 5CSS CSS-008 None Low 4 Medium 5CSS I-CT-03B Medium to High High CSS-009 None Low 4 Medium 5CSS CSS-010 None Low 4 Medium 5CSS 1-CT-04A Medium to High High CSS-01 I None Low 4 Medium 5CSS CSS-012 None Low 4 Medium 5CSS CSS-013 None Low 4 Medium 5CSS 1-CT-04B Medium to High High CSS-014 None Low 4 Medium 5CSS CSS-015 None Low 4 Medium 5CSS I-CT-05A Medium to High High CSS-016 None Low 4 Medium 5CSS 1-CT-05B Medium to High High CSS-017 None Low 4 Medium 5CSS 1-CT07 Low to Medium Medium CSS-020 None Low 6a Low 5CSS CSS-021 None Low 6a Low 5CSS CSS-022 None Low 6a Low 5CSS CSS-023 None Low 6a Low 5CSS CSS-024 None Low 6a Low 5CSS I-CT-09A Medium to High High to Medium Medium CSS-027 None Low 6a Low 5CSS 1-CT-09B Medium to High High to Medium Medium CSS-028 None Low 6a Low 5CSS 1-CVCS06 Medium to High High to Low Low CVCS-008 None Low 7a Low 2CVCS CVCS-009 None Low 7a Low 2CVCS CVCS-010 None Low 7a Low 2CVCS CVCS-011 None Low 7a Low 2CVCS SIS-027 None Low 7a Low 3SIS SIS-028 None Low 7a Low 3SIS 1-CVCS07 Medium to High High to Low Low CVCS-012 None Low 7a Low 2CVCS CVCS-013 None Low 7a Low 2CVCS CVCS-014 None Low 7a Low 2CVCS
Attachment 2 to TXX-12023 Page 4 of 4 Summary of Changes to PRA Model Consequence Consequence Rank Associated Risk Segments Segment PRA Rev 3B PRA Rev 3C PRA Rev 3D Rank at Risk DMs DM Risk Risk System I-CVCS08 Medium to High High to Low Low CVCS-015 None Low 7a Low 2CVCS CVCS-016 None Low 7a Low 2CVCS CVCS-017 None Low 7a Low 2CVCS CVCS-018 None Low 7a Low 2CVCS CVCS-019 None Low 7a Low 2CVCS CVCS-020 None Low 7a Low 2CVCS SIS-029 None Low 7a Low 3SIS 1-CVCS16 Medium to Low Low to Medium Medium RCS-010 TT Medium 5a Medium 1RCS RCS-009 None Low 6a Low IRCS 1-FW-03A Medium to High High FWS-024 None Low 4 Medium 6FWS 1-FW-03B Medium to High High FWS-025 None Low 4 Medium 6FWS I-FW-03C Medium to High High FWS-027 None Low 4 Medium 6FWS 1-FW-03D Medium to High High FWS-028 None Low 4 Medium 6FWS 1-RHR03A High to Medium Medium SIS-046 None Low 6a Low 3SIS RHRS-004 None Low 6a Low 4RHRS RHRS-005 None Low 6a Low 4RHRS RHRS-006 None Low 6a Low 4RHRS 1-RHR-03B High to Medium Medium RHRS-007 None Low 6a Low 4RHRS RHRS-008 None Low 6a Low 4RHRS RHRS-009 None Low 6a Low 4RHRS 1-RHRO8A Medium to High High to Medium Medium SIS-052 None Low 6a Low 3SIS SIS-052 None Low 6a Low 3SIS 1-RHR-08B High to Medium Medium not used in originalanalysis, listedfor information only 1-SI-01 Medium to High High to Low Low SIS-058 None Low 7a Low 3SIS SIS-062 None Low 7a Low 3SIS SIS-063 None Low 7a Low 3SIS SIS-064 None Low 7a Low 3SIS SIS-065 None Low 7a Low 3SIS SIS-066 None Low 7a Low 3SIS 1-SI-02 High to Low Low not used in originalanalysis, listedfor information only to TXX-12023 Page 1 of 2 Update to Table on Inspection Location Comparison CPNPP Unit 1 - Inspection Location Selection Comparison Between Original Approved and Updated RI-ISI Programs by Risk Category System(') Risk Consequence Failure Potential Code Original Interval 3 Update Category Rank Rank DMs Rank Category Weld RI-ISI Other(2) Weld RI-ISI Other(2)
RCS 2 High High TASCS, Medium B-i 7 2 7 3 RCS 2 High High TASCS Medium B-J 13 4 13 4 RCS 2 High High TT Medium B-F 1 0 1 1 RCS 2 High High TT Medium B-J 11 2 11 2 RCS 4 (2) Medium High None Low B-F 19 14 20 8 RCS 4 Medium High None Low B-J 205 29 223 26 RCS 5 Medium Medium TASCS Medium B-J 20 2 20 2 RCS 5 Medium Medium TT Medium B-J 44 4 44 5 RCS 5 Medium Medium TT Medium B-J 1 1 1 1 RCS 6 Low Medium None Low B-J 61 0 61 0 RCS 7 Low Low None Low B-J 15 0 15 0 CVCS 6 Low Medium None Low B-J 47 0 47 0 C-F-1 231 0 18 0 CVCS 6 Low Low TT Medium B-J 8 0 8 0 CVCS 7 Low Low None Low B-j 30 0 30 0 C-F-1 0 0 235 0 SIS 4 Medium High None Low B-J 79 7 79 7 C-F-1 98 11 136 18 SIS 5 Medium Medium IGSCC Medium B-J 12 2 12 2 SIS 6 Low Medium None Low B-J 95 0 95 0 C-F-1 596 0 425 0 SIS 6 Low Low IGSCC Medium B-J 22 0 22 0 SIS 7 Low Low None Low B-J 119 0 119 0 C-F-1 106 0 340 0 RHRS 4 Medium High None Low B-J 12 2 12 2 C-F-1 246 24 120 12 RHRS 6 Low Medium None Low C-F-1 8 0 134 0 to TXX-12023 Page 2 of 2 Update to Table on Inspection Location Comparison CPNPP Unit 1 - Inspection Location Selection Comparison Between Original Approved and Updated RI-ISI Programs by Risk Category System(') Risk Consequence Failure Potential Code Original Interval 3 Update Category Rank Rank DMs Rank Category Weld RI-ISI Other(2) Weld RI-ISI Other(2)
CSS 4 Medium High None Low C-F-1 10 1 176 18 CSS 6 Low Medium None Low C-F-1 178 0 125 0 CSS 7 Low Low None Low C-F-1 234 0 357 0 FWS 4 (1) Medium High None Low C-F-2 0 0 100 12 FWS 5 (3) Medium Medium TASCS, Medium C-F-2 8 1 8 1 FWS 6 (3) Low Medium None Low C-F-2 435 0 277 0 MSS 6 Low Medium None Low C-F-2 165 0 170 0 AFW 4 (1) Medium High None Low C-F-2 0 0 (3) 81 9 (3) 3136 106 3542 133 Notes change from original: 22 1 Systems were described in Table 3.1-2 of the original submittal, with the exception of AFW - Auxiliary Feedwater. This ASME Code Class 2 system consists of 4 segments with 81 elements.
2 The column labeled "Other" is generally used to identify augmented inspection program locations that are credited beyond those locations selected per the RI-ISI process, as addressed in Section 3.6.5 of EPRI TR-112657. This option was not applicable for the CPNPP RI-ISI application. The "Other" column has been retained in this table solely for uniformity purposes with other RI-ISI application template submittals.
3 Due to a change in ASME Section XI Code criteria, 4" NPS Class 2 auxiliary feedwater piping was added to the ISI Program, and therefore the RI-ISI Program, for the first time during the second RI- ISI period. As such, there were no welds associated with this piping during the original RI-ISI application.