ML13247A777
| ML13247A777 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 02/09/2014 |
| From: | Meena Khanna Plant Licensing Branch 1 |
| To: | Ossing M, Walsh K NextEra Energy Seabrook |
| Lamb J, DORL, 415-3100 | |
| References | |
| TAC MF2741 | |
| Download: ML13247A777 (13) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 February 9, 2014 Mr. Kevin Walsh, Site Vice President c/o Michael Ossing Seabrook Station NextEra Energy Seabrook, LLC P.O. Box 300 Seabrook, NH 03874
SUBJECT:
SEABROOK STATION, UNIT 1- REQUEST FOR RELIEF RA-13-001 TO USE AN ALTERNATIVE TO THE REQUIREMENTS OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS BOILER AND PRESSURE VESSEL CODE, SECTION XI (TAC NO. MF2731)
Dear Mr. Walsh:
By e-mail dated August 30, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13247A701), as supplemented by e-mail dated August 30, 2013 (ADAMS Accession No. ML13247A702), NextEra Energy Seabrook, LLC (NextEra or the licensee) requested relief from the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, Subarticle IWA-4000, at Seabrook Station, Unit 1 (Seabrook).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (1 0 CFR) 50.55a(a)(3)(ii),
the licensee requested to use the alternative in Relief Request RA-13-001, on the basis that complying with the specified ASME Code requirement would result in hardship or unusual difficulty. Relief Request RA-13-001 is applicable to the alternative repair of the service water (SW) pipe. As a result of the U.S. Nuclear Regulatory Commission (NRC) staff's requests for additional information (RAI), by e-mail dated August 30, 2013 (ADAMS Accession No. ML13247A781 ), the licensee responded to the RAis in the supplemental e-mail dated August 30, 2013. Relief Request RA-13-001 provides temporary repair of the SW piping until the next refueling outage (RFO) which is scheduled for spring 2014. The affected piping is the ASME Code Class 3, "B" Train 24-inch diameter SW supply pipe, line number SW-1802-004-153-24".
The NRC staff determined that the proposed alternative provides reasonable assurance of structural integrity and leak tightness of the subject SW piping. The NRC staff found that complying with the specified ASME Code requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concluded that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(a)(3)(ii) and is in compliance with the requirements of the ASME Code,Section XI, for which the relief was not requested. Therefore, during a conference call on August 31, 2013 (ADAMS Accession No. ML13247A756), the NRC staff verbally authorized the use of Relief Request RA-13-001 at Seabrook effective up to the next RFO, currently scheduled for spring 2014.
K. Walsh All other requirements of ASME Code,Section XI for which relief has not been specifically requested and approved remain applicable, including third-party review by the Authorized Nuclear lnservice Inspector.
As required by NRC procedure, the licensee submitted the formal relief request by letter dated September 4, 2013 (ADAMS Accession No. ML13252A230).
Enclosed is the NRC staff's safety evaluation.
If you have any questions, please contact me at 301-415-3100 or via e-mail at John. Lamb@nrc.gov.
Sincerely, Meena Khanna, Chief Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-443
Enclosure:
Safety Evaluation cc w/encl: Distribution via Listserv
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- "" SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR RELIEF RA-13-001- REPAIR OF SERVICE WATER PIPING NEXTERA ENERGY SEABROOK, LLC SEABROOK STATION, UNIT 1 DOCKET NO. 50-443
1.0 INTRODUCTION
By e-mail dated August 30, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13247A701), as supplemented by e-mail dated August 30, 2013 (ADAMS Accession No. ML13247A702), NextEra Energy Seabrook, LLC (NextEra or the licensee) requested relief from the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, Subarticle IWA-4000, at Seabrook Station, Unit 1 (Seabrook).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (1 0 CFR) 50.55a(a)(3)(ii),
the licensee requested to use the alternative in Relief Request RA-13-001, on the basis that complying with the specified ASME Code requirement would result in hardship or unusual difficulty. Relief Request RA-13-001 is applicable to the alternative repair of the service water (SW) pipe. As a result of the U.S. Nuclear Regulatory Commission (NRC) staff's requests for additional information (RAI), by e-mail dated August 30, 2013 (ADAMS Accession No. ML13247A781), the licensee responded to the RAis.
Relief Request RA-13-001 provides temporary repair of the SW piping until the next refueling outage (RFO), which is scheduled for spring 2014. The affected piping is the ASME Code Class 3, "B" Train 24-inch diameter SW supply pipe, line number SW-1802-004-153-24", which supplies cooling water to the Primary Component Cooling Water (PCCW) Heat Exchanger CC-E-17 -B for the purpose of removing heat from systems and components during normal plant operations and emergency plant evolutions. The ASME Code component associated with this request is a Class 3 piping component in the SW system in which a flaw has been detected.
There is one area affected by a localized flaw.
As documented in an e-mail dated August 31, 2013 (ADAMS Accession No. ML13247A756),
during a conference call, the NRC staff verbally authorized the use of Relief Request RA-13-001 at Seabrook effective up to the next RFO, currently scheduled for spring 2014. As required by NRC procedure, the licensee submitted the formal relief request by letter dated Enclosure
September 4, 2013 (ADAMS Accession No. ML13252A230). This safety evaluation documents the NRC staff's detailed technical basis for the verbal authorization.
2.0 REGULATORY EVALUATION
In this relief request, the licensee requested authorization of an alternative to the requirements of Article IWA-4412 of Section XI of the ASME Code pursuant to 10 CFR 50.55a(a)(3)(ii).
The regulations in 10 CFR 50.55a(g)(4) specify that ASME Code Class 1, 2, and 3 components (including supports) must meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME Code,Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that in-service 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), 12 months prior to the start of the 120-month interval, subject to the conditions listed therein.
Pursuant to 10 CFR 50.55a(a)(3), alternatives to the ASME Code requirements may be authorized by the NRC if the licensee demonstrates that: (i) the proposed alternative provides 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.
The applicable requirements from which the relief is requested is the ASME Code Section XI, 2004 Edition, with no Addenda, Articles IWA-4412, IWA-4421, and IWA-4340.
IWA-4412 states: "Defect removal shall be accomplished in accordance with the requirements of IWA-4420."
IWA-4421 (d) states: "Defect removal or mitigation by modification shall be in accordance with IWA-4340."
IWA-4340 states, in part, that: "Modification of items may be performed to contain or isolate a defective area without the removal of the defect. ... "
Based on the above, and subject to the following technical evaluation, the NRC staff concludes that regulatory authority exists for the licensee to request the use of an alternative and the NRC to authorize the alternative proposed by the licensee.
3.0 TECHNICAL EVALUATION
3.1 Relief Request RA-13-001 3.1.1 ASME Code Component Affected The component affected is a 24-inch Nominal Pipe Size (NPS) carbon steel piping with a nominal wall thickness of 0.375-inch. The application of this alternative is to perform a temporary, non-Code repair to the SW piping. This non-Code repair will consist of the addition of a 6-inch nominal diameter weldolet, weld-neck flange, and blind flange over the identified localized flawed area. The general configuration for the repair is shown in Figure 1: Proposed 6-inch NPS Weldolet, Weld Neck Flange, and Blind Flange in the licensee's letter dated September 4, 2013.
3.1.2 Applicable Code Edition and Addenda Seabrook is in its third 10-year in service inspection (lSI) interval, which ends August 18, 2020.
The applicable Code of record for the current third 10-year lSI program is the ASME Code,Section XI, 2004 Edition, with no Addenda. The affected portion of the SW piping was designed and constructed in accordance with the requirements of the ASME Code, Section Ill, Subsection ND, 1977 Edition, with no Addenda.
3.1.3 Applicable Code Requirement The applicable requirements from which the relief is requested is the ASME Code,Section XI, 2004 Edition, with no Addenda, Sections IWA-4412, IWA-4421, and IWA-4340.
IWA-4412 states: "Defect removal shall be accomplished in accordance with the requirements of IWA-4420."
IWA-4421 (d) states: "Defect removal or mitigation by modification shall be in accordance with IWA-4340."
IWA-4340 states, in part, that: "Modification of items may be performed to contain or isolate a defective area without the removal of the defect. ... "
3.1.4 Reason for Request (as stated by the licensee)
On August 7, 2013, with Seabrook Station in operation at 100% power, a through-wall leak was identified in a section of SW system piping. NextEra performed Ultrasonic Test examination to characterize the affected area and prepared an evaluation documented in [an e-mail dated August 30, 2013.].
The examination and evaluations concluded that the leakage is a result of wall-thinning due to localized corrosion on the inside of the pipe. On August 28, 2013, the leakage increased as a result of changing the operating line-up to perform a surveillance procedure. A housekeeping patch was installed to stop the leakage. Additional ultrasonic examinations show that the wall thinning area
has remained constant, however, due to increased pressure as a result of the alternate piping line-up, the leakage increased.
The remaining wall thickness currently provides sufficient structural integrity to maintain operability of the SW system.
3.1.5 Proposed Alternative and Basis for Use NextEra proposed the encapsulation of the identified pipe wall flaw by the addition of a 6-inch NPS weldolet, weld neck flange, and blind flange as depicted in Figure 1 of the licensee's letter dated September 4, 2013.
By letter dated September 4, 2013, the licensee provided the following responses to the requirements of IWA-4340:
3.1.5.1 Flaw Sizing and Characterization On August 7, 2013 an Ultrasonic Test (UT) examination was performed at an identified through wall leak on line SW-1802-004-153-24". The area was identified by discovery of a slow (several drops per minute) leak. The examination revealed that the through wall leak at this location was the result of a single isolated flaw that appears to be related to corrosion. Encoded UT data was collected at this location and was used to evaluate the through wall leakage area. A 3-inch by 6-inch area surrounding the flaw was selected for the encoded examination. This encoded area encompassed the entire flawed area. Normal intermittent responses could not be received in an area specifically bounded by where the inside surface response was initially lost. This resulted in a conservative bounded flaw area of 2. 327 -inches circumferentially by 1.500-inches axially. Wall thickness readings could not be obtained within this region. However, it was identified that there is an abrupt increase in thickness to nominal wall (0.375 inch) and above outside this region.
During the angle beam exam, the flaw could be seen in all four directions which is not typical for planar flaws. For structural evaluation purposes, the flaw was considered non-planar. At the time of the August 7, 2013 examination no visible through wall hole was identified. On August 20, 2013 an increase in through wall flow was identified. A subsequent UT examination was performed. It concluded that the bounding area of 2.327-inches by 1.500-inches remained the same with no reportable thickness recorded in this area. However, a visible through wall hole estimated to be 0.250-inches in diameter was identified. In accordance with ASME Code Case N-513-3, the entire circumference of the piping at the through wall leak location was also examined with no other defects identified.
3.1.5.2 Degradation Mechanism As discussed in Section [3.1. 5.1] above, based upon the Non-Destructive Examination (NDE), the localized flaw appears to be seawater corrosion related.
See further discussion on this in Section [3.1.5.4].
- 3. 1. 5. 3 Flaw Evaluation A flaw evaluation, in accordance with ASME Code Case N-513-3, was performed with the through wall flaw size assumed to be the bounding area of 2.327-inches by 1.500-inches. The evaluation concluded that structural integrity is maintained.
This evaluation is provided in [Seabrook Calculation C-S-1-45893-CALC, Rev. 000, "Code Case N-513-3 Pipe Wall Flaw Evaluation for SW-1802-004-153-24," which is attached as Reference 2 to the submittal dated September 4, 2013]. In accordance with Code Case N-513-3, augmented inspections were scheduled to be performed to determine the extent of condition.
3.1.5.4 Flaw Growth Rate As previously stated in Section [3.1.5.2], the cause of the degradation is from localized corrosion. The typical corrosion rate used in Seabrook SW piping evaluations is 30 mils per year (mpy). However, the current identified wall defect resides in piping, which was recently replaced during [RF0]-14 during April 2011, concluding that an accelerated (presently unknown) mechanism exists within the bounding area. The NDE identified nominal (and above) pipe wall thickness around the bounding area. Based upon this, it is assumed that while further degradation will occur within the bounding area, the surrounding area wall loss will be such that the ASME Code required minimum pipe wall thickness, calculated to be 0.1 05-inch in Reference 2, [of the letter dated September 4, 2013], will not be violated during the duration of the proposed temporary non-Code repair. To provide further assurance, a 6-inch weldolet has been selected for use.
The sizing of the weldolet (6 inch nominal) was based upon the identified wall thickness of the piping and its installation position with respect to the bounded flaw size (2.327 by 1.5 inch). The weldolet will be welded to pipe wall thickness verified to be of a thickness of 0.375 inch or better. The typical corrosion rate used by Seabrook is 30 mils per year. To proactively address the corrosion potential within the bounded area, a factor of 4 is applied resulting in a rate of 120 mils per year. Although the installation duration is less than a year (next refueling outage is spring 2014) 120 mils is used. The resulting pipe wall under the weldolet and weldment will therefore be reduced from to 0.375- 0.120 =0.255 inch. The ASME Section Ill Code requirement for minimum pipe wall is 0.105 inch, calculated in calculation C-S-1-45893. As the pipe wall with future metal loss, calculated to be 0.255 inch, exceeds the Code minimum of 0.105 inch, structural integrity of the repair will be maintained. The 6.6875 inch inside diameter of the weldolet in relationship with the major axis dimension of the bounded flaw (2.327 inch) provides sufficient metal such that further corrosion will not affect the integrity of the repair.
3.1.6 Duration of Proposed Alternative The licensee stated that the temporary non-Code repair to the Seabrook SW system will remain in place until RFO 16, which is currently scheduled for spring 2014. Should Seabrook enter a shutdown of sufficient duration prior to RFO 16, the temporary non-Code repair will be replaced by a Code-acceptable repair.
3.2 NRC Staff Evaluation 3.2.1 Encapsulation Device Design A diagram of the proposed encapsulation device is shown in Figure 1: Proposed 6-inch NPS Weldolet, Weld Neck Flange, and Blind Flange, of the relief request, dated September 4, 2013.
As identified in Figure 1, the pipe wall area encapsulated by the weldolet is a 6.688-inch diameter circle, providing sufficient metal area around the bounding area of 2.327-inches by 1.500-inches. It is because of the localized nature of the identified flaw that, while structural integrity is ensured, a temporary non-Code repair is being requested.
The pressure rating of the weldolet and blind flange is 150 pounds per square inch (psi) and 200 degrees Fahrenheit (°F). The design pressure is 150 psi and design temperature is 200 °F.
Normal operating pressure is 75 psi and normal operating temperature is 65 oF maximum and 35 oF minimum. The weldolet is ASME SA material and meets the ASME Code, Section Ill NO requirement for branch connections. The welding will be performed using a qualified procedure that meets the ASME Code,Section IX requirements for an open root, full penetration weld.
The branch connection will meet the ASME Code, Section Ill, NO requirements for fabrication.
3.2.2 Application NextEra proposed the encapsulation of the identified pipe wall flaw by the addition of a 6-inch NPS weldolet, weld neck flange, and blind flange as depicted on Figure 1 in the licensee's letter dated September 4, 2013.
The sizing of the weldolet (6-inch nominal) was based upon the identified wall thickness of the piping and its installation position with respect to the bounded flaw size (2.327 by 1.5-inch).
The weldolet will be welded to a pipe wall thickness verified to be of a thickness of 0.375-inch or better. The typical corrosion rate used by Seabrook is 30 mpy. To address the unknown corrosion rate within the bounded area, a factor of 4 is applied resulting in a rate of 120 mpy.
Although the installation duration is less than a year (next RFO is spring 2014), 120 mils is used. The resulting pipe wall under the weldolet and weldment will therefore be reduced to 0.375-0.120 = 0.255-inch. The ASME Code, Section Ill requirement for minimum pipe wall is 0.1 05-inch, calculated in calculation C-S-1-45893. As the pipe wall with future metal loss, calculated to be 0.255-inch, exceeds the Code minimum of 0.1 05-inch, structural integrity of the repair will be maintained. The 6.6875-inch inside diameter of the weldolet in relationship with the major axis dimension of the bounded flaw (2.327-inch) provides sufficient metal such that further corrosion will not affect the integrity of the repair.
3.2.3 Pre-Installation Inspection and Preparation The pre-installation NDE requirements for the weldolet consists of the verification of ASME material, the verification of proper weld joint fit-up and a final Visual (VT) and Magnetic Particle exam of the final weld.
The NDE examination methods performed will meet the ASME Code,Section XI, IWA-4500 requirements.
3.2.4 Characterization of Degradation The cause of the degradation is from localized seawater corrosion-related. The typical corrosion rate used in Seabrook SW piping evaluations is 30 mpy.
3.2.5 Welding of Encapsulation Device The licensee's proposed alternative is based on ASME Code Case N-513-3. The non-Code repair consisted of the addition of a 6-inch nominal diameter weldolet, weld-neck flange, and blind flange over the identified localized flawed area. As stated by the licensee, the pressure rating of the weldolet and blind flange meets the design pressure and temperature of the piping system and will be sufficient for the normal operation pressure and temperature. The weldolet is ASME qualified material and meets the ASME Section Ill ND requirement for branch connections. The welding was performed using a qualified procedure that meets the ASME Section IX requirements for an open root, full penetration weld. The branch connection met the ASME Section Ill ND requirements for fabrication.
3.2.6 Acceptance Examination The post-installation NDE requirements consist of a VT -2 for leakage in accordance with ASME Code,Section XI, IWA-5000.
The acceptance criteria are in accordance with the original construction code, ASME Code, Section Ill ND, requirements.
The NDE examination methods performed will meet the ASME Code,Section XI, IWA-4500 requirements.
3.2.7 In-Service Monitoring As discussed in Section 3.1.5.1 of this safety evaluation, nominal pipe wall exists around the bounding area of 2.327-inches by 1.500-inches. The proposed temporary non-Code repair will be installed on this nominal pipe wall. The licensee stated in its submittal that periodic UT inspections of no more than 30-day intervals around the installed weldolet will be performed to identify wall loss propagating outside the encompassed area.
3.2.8 Hardship The licensee stated in its submittal dated August 30, 2013, that Section XI of the ASME Code specifies Code-acceptable repair methods for flaws that exceed Code acceptance limits for piping that is in service. A Code repair is required to restore the structural integrity of flawed ASME Code piping, independent of the operational mode of the plant when the flaw is detected.
Repairs not in compliance with Section XI of the ASME Code are non-Code repairs. However, the required Code repair may be impractical for a flaw detected during plant operation unless the facility is shut down. Temporary non-Code repairs of Class 3 piping are unacceptable without specific written relief from the Code by the NRC. The flaw that has been detected is in a section of the SW piping that cannot be isolated to complete a Code-acceptable repair. As it is impractical to complete a Code-acceptable repair to the SW leaks at Seabrook without shutting down the plant, relief is requested to use a non-Code repair until the next RFO shutdown, scheduled for spring 2014, or a shutdown of a duration long enough to complete a Code-acceptable repair.
It is impractical to complete a Code-acceptable repair to the identified SW leak at Seabrook without shutting down the plant. Shutting down the plant in mid-cycle creates undue and unnecessary stress on plant systems, structures, and components.
3.3 Summary The NRC staff evaluated the technical aspects of this request against the criteria contained in 10 CFR 50.55a(3)(ii). In considering hardship or unusual difficulty, the NRC staff notes that the removal of the defective portion of the pipe as required by IWA-4412 would have increased the rate of leakage from the pipe to such an extent that repairs could not be made without removing the pipe from service. The NRC staff concludes that the licensee's assessment that a permanent, Code-compliant repair could not be made without removing the affected piping from service to be reasonable. The NRC staff also notes that the licensee proposes that (a) plant Technical Specification 3/4.7.4, "Service Water System/Ultimate Heat Sink," provides for continued plant operation for not longer than 72 hours3 days <br />0.429 weeks <br />0.0986 months <br /> with one train of SW out of service; (b) that a substantial portion of the available 72-hour window would be performing the complex operation of isolation and draining of the affected piping; and (c) given the amount of time required to isolate and drain the piping, it is improbable that the necessary repairs could have been completed within the allotted time. Thus, shutting down the plant in mid-cycle creates undue and unnecessary stress on plant systems, structures, and components. The NRC staff concludes that the permanent repairs could not be completed within the available time to be reasonable. The NRC staff concludes that making Code-compliant repairs to the subject piping would have required a plant shutdown and therefore constituted a hardship.
In considering a compensating increase in level of quality and safety, the NRC staff used guidance provided in the ASME Code Case N-513-3, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 and 3 Piping,Section XI, Division 1." The NRC staff concludes that analyses, which are conducted in accordance with an accepted Code Case, and are conducted to the satisfaction of the NRC, are sufficient to demonstrate reasonable assurance of structural integrity or leak tightness of the subject components. The NRC staff further concludes that the licensee's proposal was consistent with each requirement contained in Code Case N-513-3. Based on the consistency between the Code Case and the
technical content of the licensee's proposal, the NRC staff concludes that the licensee's proposal provides reasonable assurance of structural integrity and leak tightness of the subject components and that requiring the licensee to make a Code-compliant repair, as opposed to utilizing the proposed alternative, did not result in a compensating increase in the level of quality and safety.
The NRC staff was concerned regarding the potential of continued wall thinning at the repaired area that may affect the branch connection (weldolet). The licensee performed an analysis of the flaw growth rate to address the unknown corrosion rate within the bounded area of degradation. As stated by the licensee, the typical corrosion rate used in piping evaluations is 30 mpy. However, the current identified wall defect resides in piping, which was recently replaced during RFO 14 during April 2011, demonstrating that an accelerated (presently unknown) mechanism exists within the bounding area of degradation. Thus, the licensee applied a conservative safety factor of 4 to the corrosion rate to project the potential wall thinning to account for the unknown mechanism and the duration that which the repair is intended to remain installed. The licensee concluded that there is sufficient base pipe metal such that further corrosion will not affect the integrity of the repair. The NRC staff performed an independent calculation and verified that the pipe underneath the weldolet will have sufficient wall thickness to maintain its structural integrity during the effective period of the relief request.
The NRC staff, therefore, concludes that the licensee's proposal to be acceptable and that the structural integrity of the repair will be maintained and failure of the repair due to corrosion is unlikely.
The licensee welded a 6-inch nominal diameter branch connection (a weldolet and blind flange) at the defective area in accordance with the ASME Code,Section XI and the branch connection meets the ASME Section Ill Article ND requirements for fabrication. The weldolet was welded to the pipe base metal which has sufficient wall thickness to provide structural support. The weldolet is rated at a pressure and temperature of 150 psi and 200 °F, respectively. The licensee performed NDE of the branch connection installation in accordance with the ASME Code,Section XI and the acceptance criteria was based on the ASME Code, Section Ill, Article ND. The total branch connection weighs 77.2 pounds. The NRC staff concludes that the pipe is adequately supported and restrained in the vicinity of the repaired area. Therefore, the weight of the branch connection will not significantly affect the pipe stresses during seismic conditions. The NRC staff determined that the branch connection is installed, examined, and tested based on the ASME Code, Sections Ill and XI.
In summary, the NRC staff concludes that the proposed alternative provides adequate technical basis with regard to pre-installation preparation, flaw characterization, design analysis, welding, material selection, acceptance examination, and in-service monitoring. Therefore, the NRC staff concludes that the encapsulation device provides reasonable assurance of structural integrity of the repaired SW piping.
Based on the above, the NRC staff concludes that the licensee's proposed alternative provides adequate technical basis for both criteria contained in the 10 CFR 50.55a(a)(3)(ii) and that the encapsulation device provides reasonable assurance of structural integrity and leak tightness of the subject SW piping.
4.0 CONCLUSION
As set forth above, the NRC staff determines that the proposed alternative provides reasonable assurance of structural integrity and leak tightness of the subject SW piping and that complying with the specified ASME Code requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(a)(3)(ii) and is in compliance with the requirements of the ASME Code,Section XI, for which the relief was not requested. Therefore, on August 31, 2013, the NRC staff verbally authorized the use of Relief Request RA-13-001 at Seabrook, effective up to the next RFO, currently scheduled for spring 2014.
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 lnservice Inspector.
Principal Contributors: S. Vitto and J. Tsao, NRR Date: February 9, 2014
K. Walsh All other requirements of ASME Code,Section XI for which relief has not been specifically requested and approved remain applicable, including third-party review by the Authorized Nuclear lnservice Inspector.
As required by NRC procedure, the licensee submitted the formal relief request by letter dated September 4, 2013 (ADAMS Accession No. ML13252A230).
Enclosed is the NRC staff's safety evaluation.
If you have any questions, please contact me at 301-415-3100 or via e-mail at John. Lamb@nrc.gov.
Sincerely, Ira/
Meena Khanna, Chief Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-443
Enclosure:
Safety Evaluation cc w/encl: Distribution via Listserv DISTRIBUTION:
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