ML033180628
| ML033180628 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 11/14/2003 |
| From: | Gramm R NRC/NRR/DLPM/LPD4 |
| To: | Blevins M TXU Energy |
| Thadani M, NRR/DLPM, 415-1476 | |
| References | |
| TAC MB7772, TAC MB7773 | |
| Download: ML033180628 (9) | |
Text
November 14, 2003 Mr. Michael R. Blevins Senior Vice President &
Principal Nuclear Officer TXU Energy Attn: Regulatory Affairs Department P. O. Box 1002 Glen Rose, TX 76043
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION, UNIT 1 - REQUEST FOR RELIEF FROM THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS BOILER AND PRESSURE VESSEL CODE, SECTION XI REQUIREMENT, CONCERNING SECOND TEN-YEAR INSERVICE INSPECTION INTERVAL (TAC NOS. MB7772 AND MB7773)
Dear Mr. Blevins:
By "CPSES-200300305, (CPSES) - Relief Request B-2 & C-4 for Unit 1 Inservice Inspection (ISI) from 1986 Edition of ASME Code,[[ASME section" contains a listed "[" character as part of the property label and has therefore been classified as invalid., No Addenda Interval Start Date: August 14, 2000, Second Interval)|letter dated February 14, 2003]], as supplemented by letter dated July 10, 2003, TXU Generation Company LP (licensee) requested relief from certain requirements of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) for volumetric examination coverage requirements for examination categories C-C and B-J welds at Comanche Peak Steam Electric Station, Unit 1.
The Nuclear Regulatory Commission (NRC) staff has reviewed the licensees request and concludes that requiring the licensee to perform design modifications to obtain the required 100% coverage of examination is impractical and would result in a significant burden on the licensee. The proposed alternatives provide assurance of the continued structural integrity of the welds and would provide an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(g)(6)(i), relief requests C-4 and B-2 are authorized by law for the second inservice inspection interval. Granting these reliefs will not endanger life or property or the common defense and security, and is 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. 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 Authorized Nuclear Inservice Inspector.
M. R. Blevins The enclosed safety evaluation outlines the NRC staffs evaluation supporting the above conclusions. If you should have questions regarding the NRC staffs safety evaluation, please contact Mohan C. Thadani, at (301) 415-1476.
Sincerely,
/RA/
Robert A. Gramm, Chief, Section 1 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No.: 50-445
Enclosure:
Safety Evaluation cc w/encl: See next page
- No legal objection OFFICE PDIV-1/PM PDIV-1/LA EMCB/SC OGC**
PDIV-1/SC NAME MThadani:sab DJohnson TChan*
RHoefling RGramm DATE 11/12/03 11/12/03 10/29/03 11/3/03 9/03/03
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SECOND TEN-YEAR INSERVICE INSPECTION PROGRAM INTERVAL REQUEST FOR RELIEF NOS. C-4 AND B-2 TXU GENERATION COMPANY LP COMANCHE PEAK STEAM ELECTRIC STATION, UNIT 1 DOCKET NO. 50-445
1.0 INTRODUCTION
The Inservice Inspection (ISI) of the American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel Code (Code) Class 1, Class 2, and Class 3 components is to be performed in accordance with Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, of the ASME Code and applicable edition and addenda as required by 10 CFR 50.55a(g), except where specific relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Pursuant to 10 CFR 50.55a(a)(3), alternatives to the requirements of paragraph (g) may be used when authorized by the Nuclear Regulatory Commission (NRC), if the applicant demonstrates that: (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.
Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components (including supports) will meet the requirements, except the design and access provisions and the 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 ten-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 ISI Code of record for Comanche Peak Steam Electric Station, Unit 1 (CPSES) for the second ten-year ISI interval is the 1986 Edition of the Code, no Addenda.
By "CPSES-200300305, (CPSES) - Relief Request B-2 & C-4 for Unit 1 Inservice Inspection (ISI) from 1986 Edition of ASME Code,[[ASME section" contains a listed "[" character as part of the property label and has therefore been classified as invalid., No Addenda Interval Start Date: August 14, 2000, Second Interval)|letter dated February 14, 2003]], as supplemented by letter dated July 10, 2003, TXU Generation Company LP (the licensee), requested relief under Relief Request Nos. C-4 and B-2, for CPSES from the surface and volumetric examination coverage requirements for examination categories C-C and B-J welds.
2.0 ISI PROGRAM RELIEF REQUEST NO. C-4, SURFACE EXAMINATION LIMITATION FOR CODE CATEGORY C-C WELDS 2.1 System/Component for Which Relief is Requested Chemical and Volume Control Pump TBX-CSAPCH-01. ASME Class 2 Integrally Welded Pump Attachments.
Weld No. TBX-2-3110-3WS Weld No. TBX-2-3110-4WS 2.2 Code Requirement from Which Relief is Requested The 1986 Edition of ASME Code,Section XI, Table IWC-2500-1, Examination Category C-C, Code Item B3.30, Figure IWC-2500-5 requires a surface examination which includes 100% of the welded attachment length, once during the ten-year interval.
2.3 Licensees Proposed Alternative to Code The licensee stated it will complete a best effort Dye Penetrant (PT) examination and will obtain coverage equivalent to 77% of the weld length for attachment welds TBX-2-3110-3WS and TBX-2-3110-4WS.
2.4 Licensees Basis for Relief Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee stated that the examination coverage is limited due to interferences from the housing seal and pump base plate and to gain 100% coverage would require a design modification. Therefore, the Code-required surface examination coverage by the PT method cannot be achieved and that the best effort examination resulted in coverage of 77% of the required area. To gain access for examination would require a design modification which would be impractical and impose a significant burden on the licensee. The licensee indicated that the most recent examination showed no change in the recordable indication in the past 10 years; therefore, no pattern of degradation exists.
2.5 Evaluation The 1986 Edition of ASME Code Section XI, Table IWC-2500-1, Examination Category C-C, Code Item B3.30, Figure IWC-2500-5 requires a surface examination which includes 100% of the welded attachment length, once during the ten-year interval.
The NRC staff review of the data submitted for the subject welds notes that there was no change in the recordable indication previously identified on October 31, 1992, with the amount of coverage obtained. The data reports also note the licensee performed a comparison of the results with the previous interval testing results and no change was noted. The staff concludes from the information provided by the licensee that any pattern of degradation would have been identified with the coverage obtained, and is therefore, acceptable.
Based on the above discussion, the NRC staff considers it impractical to redesign the subject welds in order to obtain the Code-required surface coverage and the alternative provides reasonable assurance of the structural integrity of the weld.
2.6 Conclusion The staff concludes that requiring the licensee to perform a design modification to obtain 100% coverage is impractical and would result in a significant burden, and that the testing performed provides adequate assurance of the continued structural integrity of the welds. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) for the second ISI interval for CPSES Relief Request No. C-4. This grant of relief is authorized by law and will not endanger life or property or the common defense and security, and is 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. 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.
3.0 ISI PROGRAM RELIEF REQUEST NO. B-2, VOLUMETRIC EXAMINATION LIMITATION FOR CODE CATEGORY B-J WELDS 3.1 System/Component for Which Relief is Requested Relief is requested for the following Class 1 piping welds in the Reactor Coolant System (Pressure Relief), Category B-J, Item B9.21, 1986 Edition with no Addenda of ASME Section XI:
Weld No. TBX-1-4502-12 Weld No. TBX-1-4502-28 3.2 Code Requirement from Which Relief is Requested The Westinghouse and the Electric Power Research Institute (EPRI) Risk Informed ISI (RI-ISI) methodologies, under their respective Relief Request sections, as approved by the staff, both require greater than 90% of the volume of the weld to be examined in order to claim full credit for weld coverage.
3.3 Licensees Proposed Alternative In accordance with commitments made through its RI-ISI Program, the licensee stated it will volumetrically examine with ultrasonic testing (UT) methods, as qualified through the Performance Demonstration Initiative (PDI), Supplement 2, welds TBX-1-4502-12 and TBX-1-4502-28. The best available volumetric examination with UT techniques, as qualified through the PDI for Supplement 2 with demonstrated best effort for single side examination, were used from the accessible side of the weld. In its supplemental letter dated July 10, 2003, the licensee revised the subject relief request to include a surface examination of the subject welds.
3.4 Licensees Basis for Relief Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee stated that imposition of the Code requirements would require significant system redesign, modifications, and an increase in personnel radiation exposure to obtain a two-sided examination of the subject welds.
These two welds were the only welds identified in the line segments per the RI-ISI Program, which met the considerations for system design, the risk analysis, previous examinations, and non-destructive examination (NDE) accessibility. Additionally, these welds have been previously examined via the liquid penetrant examination method and no flaws were noted. The licensee stated that the proposed examinations provide adequate confidence that there are no matters of concern regarding the structural integrity of the subject welds.
3.5 Evaluation The Code of record for the CPSES second interval is the 1986 Edition of ASME Section XI with no Addenda. Table IWB-2500-1, Examination Category B-J, Item B9.21 requires surface examination of the entire weld length. By supplemental letter dated July 10, 2003, the licensee revised the subject relief request to include a surface examination.
Due to the high safety significance of these two welds, the licensee upgraded the examination requirements to UT under its RI-ISI Program which was approved by the staff February 15, 2001. This was the first time that ultrasonic examination had been performed on these two welds. In its July 10, 2003 supplemental letter, the licensee provided the results of the UT examination, which noted that 50% coverage was obtained and no recordable indications were noted. Previous Code-required examination was a PT examination and the licensee stated that the most recent PT showed no new indications. The NRC staff concludes from the information provided by the licensee that any pattern of degradation would have been identified with the coverage obtained, and is therefore, acceptable.
The licensee indicated in its submittal that these two welds were the only two welds identified in the line segments per the RI-ISI Program, which met the considerations for system design, the risk analysis, previous examinations, and NDE accessibility. This evaluation is consistent with the guidance provided in both RI-ISI methodologies (EPRI and Westinghouse) that have been approved by the staff. Under the relief request sections, the methodologies indicate that less than 90% coverage of a location with a high susceptibility of failure will yield more valuable information than 100% coverage at a location where a lower probability of failure exists. Based on this discussion, the NRC staff concludes that the licensee has evaluated its RI-ISI Program welds available for substitution, and that these two welds are the most suitable for testing and cannot be substituted with different welds of the same risk significance where greater coverage could be obtained. Finally, the NRC staffs review of the weld profiles submitted by the licensee indicate that a one-sided examination is the only feasible approach for volumetric examination.
Since no pattern of degradation has been identified and no suitable alternative substitution weld exists under the RI-ISI Program, the staff considers it impractical to redesign the subject welds in order to obtain the volumetric coverage, and the alternative provides reasonable assurance of the structural integrity of the weld.
3.6 Conclusion The staff concludes that requiring the licensee to perform a design modification to obtain 100% coverage is impractical and would result in a significant burden, and that the testing performed provides adequate assurance of the continued structural integrity of the welds. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) for the second ISI interval for Relief Request No. B-2, for CPSES.
This grant of relief is authorized by law and will not endanger life or property or the common defense and security, and is 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. 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 Contributor: T. Steingass Dated: November 14, 2003
March 2003 Comanche Peak Steam Electric Station cc:
Senior Resident Inspector U.S. Nuclear Regulatory Commission P. O. Box 2159 Glen Rose, TX 76403-2159 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011 Mr. Roger D. Walker Regulatory Affairs Manager TXU Generation Company LP P. O. Box 1002 Glen Rose, TX 76043 George L. Edgar, Esq.
Morgan Lewis 1111 Pennsylvania Avenue, NW Washington, DC 20004 County Judge P. O. Box 851 Glen Rose, TX 76043 Environmental and Natural Resources Policy Director Office of the Governor P. O. Box 12428 Austin, TX 78711-3189 Mr. Richard A. Ratliff, Chief Bureau of Radiation Control Texas Department of Health 1100 West 49th Street Austin, TX 78756-3189 Mr. Brian Almon Public Utility Commission William B. Travis Building P. O. Box 13326 1701 North Congress Avenue Austin, TX 78701-3326 Ms. Susan M. Jablonski Office of Permitting, Remediation and Registration Texas Commission on Environmental Quality MC-122 P. O. Box 13087 Austin, TX 78711-3087 Terry Parks, Chief Inspector Texas Department of Licensing and Regulation Boiler Program P. O. Box 12157 Austin, TX 78711