ML070360418
| ML070360418 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 02/12/2007 |
| From: | Mozafari B NRC/NRR/ADRO/DORL/LPLII-2 |
| To: | Scarola J Carolina Power & Light Co |
| Mozafari B, NRR/ADRO/DORL, 415-2020 | |
| References | |
| TAC MD2724, TAC MD2725 | |
| Download: ML070360418 (6) | |
Text
February 12, 2007 Mr. James Scarola, Vice President Brunswick Steam Electric Plant Carolina Power & Light Company Post Office Box 10429 Southport, North Carolina 28461
SUBJECT:
BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND 2 - REQUEST FOR RELIEF NO. RR-38 REGARDING PRESSURE TESTING OF DRAIN, VENT, TEST, AND FILL LINES WITHIN THE REACTOR COOLANT PRESSURE BOUNDARY (TAC NOS. MD2724 AND MD2725)
Dear Mr. Scarola:
By letter dated July 18, 2006, Carolina Power & Light Company (the licensee) requested U. S. Nuclear Regulatory Commission (NRC) approval for relief from certain requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) for the third 10-year inservice inspection (ISI) interval. Specifically, the licensee proposed an alternative examination for the ASME Code Class 1 piping segments in the reactor coolant pressure boundary drain, vent, test, and fill lines that are isolated by inboard and outboard isolation valves. The licensee proposed to conduct the pressure test with the inboard isolation valve in the closed position.
The NRC staff has reviewed the relief request and concludes that Relief Request 38 is authorized pursuant to 50.55a(a)(3)(ii) of Title 10 of the Code of Federal Regulations for the third 10-year ISI interval on the basis that the Code requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
If you have any questions regarding this approval, please contact the Brunswick Project Manager, Stewart Bailey, at 301-415-1321.
Sincerely,
/RA/
Brenda Mozafari, Chief (Acting)
Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-325 and 50-324
Enclosure:
Safety Evaluation cc w/encl: See next page
ML070360418 OFFICE LPL2-2/PM LPL2-2/LA CSGB/BC OGC LPL2-2/BC (A)
NAME SBailey BClayton AHiser S. Hamrick BMozafari DATE 2/9/07 2/6/07 2/7/07 2/9/07 2/12/07
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO INSERVICE INSPECTION PROGRAM RELIEF REQUEST NO. RR-38 BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND 2 DOCKET NUMBERS 50-325 AND 50-324
1.0 INTRODUCTION
By letter dated July 18, 2006, Carolina Power & Light Company (the licensee) submitted a request for relief (No. RR-38) related to the third 10-year interval inservice inspection (ISI) program for Brunswick Steam Electric Plant (BSEP), Units 1 and 2. The licensee proposed alternative testing for the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) Class 1 pressure retaining components in reactor coolant pressure boundary (RCPB) vent, drain, test, and fill line connections that are between the inboard and outboard isolation valves. Specifically, the licensee proposed to leave the inboard isolation valve closed when performing the system leakage test, which would isolate a small segment of Class 1 line from the system boundary for pressurization. The licensee stated that performing the pressure test with the inboard isolation valve open, as required by the Code, poses a hardship because it requires multiple entries into the drywell for the valve alignment, which exposes personnel to additional radiation, and increases the risk of failure because the lines would only have single valve isolation during the test. The licensee requested relief pursuant to Title 10 to the Code of Federal Regulations (10 CFR), Paragraph 50, Section 55a(a)(3)(ii), on the basis that compliance with the Code requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
2.0 REGULATORY REQUIREMENTS As required by 10 CFR 50.55a(g), ISI of ASME Code Class 1, 2, and 3 components be performed in accordance with Section XI of the ASME Code and applicable addenda, except where specific written relief has been granted by the Nuclear Regulatory Commission pursuant to 10 CFR 50.55a(g)(6)(i). According to 10 CFR 50.55a(a)(3), alternatives to the requirements of Section 50.55a(g) may be used, when authorized by the NRC, if an applicant demonstrates that the proposed alternatives would provide an acceptable level of quality and safety or if the specified requirement 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) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, Rules for Enclosure Inservice Inspection (ISI) 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 ISI 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 limitations and modifications listed therein. The Code of Record for the third 10-year intervals ISI program for BSEP, Units 1 and 2, is the 1989 Edition of the ASME Code,Section XI. The licensee, however, will implement provisions of the ASME Section XI, Code Case N-498-4, during the interval for the subject pressure test.
3.0 TECHNICAL EVALUATION
System/Component(s) for Which Relief is Requested RCPB vent, drain, test, and fill line connections.
ASME Code Requirements The 1989 Edition of the ASME Code,Section XI, Table IWB-2500-1, Examination Category B-P, Note 2, requires that the pressure retaining boundary during the system hydrostatic test include all Class 1 components within the system boundary. The licensee proposed to implement Code Case N-498-4, which accepts a system leakage test (IWB-5221) in lieu of the system hydrostatic test. Code Case N-498-4 requires that all Class 1 pressure retaining components within the system boundary be subject to test pressurization during the system leakage test.
Licensees Request for Relief The licensee requested relief from the requirement to pressurize, during performance of system leakage tests, the portions of the Class 1 RCPB vent, drain, test, and fill line connections that normally have the inboard isolation valve in the closed position. This would isolate a small segment of Class 1 line, between the inboard and outboard valves, from the pressurization boundary.
Licensees Basis for Requesting Relief The drain, vent, test, and fill lines within the RCPB are typical 1-inch nominal pipe size or less.
These connections include two manual isolation valves whose purpose is to satisfy the design requirement for double isolation of the RCPB. During normal operation, these manual isolation valves are maintained in the closed or lock-closed position. Thus, components downstream of the first isolation valve are not subjected to reactor coolant system pressure unless leakage through the inboard valves occurs.
As stated above, the Code requires the test pressurization to extend to all Class 1 pressure retaining components within the system boundary. To comply with this requirement, the licensee would need to open the first isolation valve during the test. Having the first isolation valve open would defeat the design requirement for double isolation of the RCPB. As such, this nonstandard configuration would increase the risk for inventory loss. Because of the potential for inventory loss, this configuration also creates safety concerns for the personnel performing the visual examination.
In addition, opening the first manual isolation valve will create a hardship in regards to personnel exposure and contamination. Opening these valves will require personnel to enter radiation fields to position the valves for the test, restore the valves following the test, and to perform the required independent valve position verification. Since these valves are typically located in close proximity to the main RCPB piping, the licensee estimates the dose associated with this effort, for each pressure test, as approximately 1.058 rem for Unit 1 and 1.308 rem for Unit 2. Further, because of the location of these valves, the risk for personnel contamination increases.
The licensee determined that opening the first isolation valve to allow pressurization of the down stream components will not increase the level of quality and safety of the plant, so placing the plant and personnel at risk is unwarranted.
Licensees Proposed Alternative Pursuant to 10 CFR 50.55a(a)(3)(ii), the licensee proposes to perform VT-2 visual examination of RCPB vent, drain, test, and fill lines connections for leakage up to and including the outboard isolation valve at the boundary extremity. This VT-2 visual examination will be performed with the inboard and outboard isolation valves in their normal closed operating position.
4.0 STAFF EVALUATION Section XI of the ASME Code of Record requires that all Class 1 components within the RCPB undergo a system leakage test at the end of each refueling outage and a system hydrostatic test at or near the end of each inspection interval. In Relief Request No. RR-38, the licensee proposed an alternative to the Code requirement for the test of the segments of the RCPB vent, drain, test, and fill line connections that are normally isolated between the inboard and outboard isolation valves, to exclude these pipe segments from being pressurized during a system leakage test. The isolation valves are configured to provide double-isolation of the reactor coolant system (RCS). Under normal plant operating conditions, the pipe segments between the isolation valves would see RCS temperature and pressure only if leakage through the inboard isolation valves occurs. For the licensee to perform the ASME Code-required test, the licensee would need to manually open the inboard valves to pressurize the pipe segments.
Pressurization by this method would preclude the RCS double valve isolation and may cause safety concerns for the personnel performing the examination.
Typical line/valve configurations are in close proximity of the RCPB main runs of pipe and thus, would require personnel entry into high radiation areas within the containment. Manual actuation (opening and closing) of these valves is estimated to expose plant personnel to approximately 1 man-rem each at Brunswick Units 1 and 2, per test. The licensee proposed to visually examine the isolation valves in the normally closed position for leaks which would indicate any evidence of past leakage during the operating cycle. Also, the RCPB vent, drain, test, and fill line connections will be visually examined with the isolation valves in the normally closed position during the 10-year system hydrostatic test. The staff believes that the licensees proposed alternative will provide reasonable assurance of operational readiness for the RCPB vent, drain, test, and fill line connections while maintaining personnel radiation exposure to as low as reasonably achievable. The staff has further determined that compliance with the Code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
5.0 CONCLUSION
Based on its review of the licensees request for relief, the staff finds that the licensees proposed alternative provides reasonable assurance of operational readiness, and compliance with the ASME Code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(ii), the alternative proposed in Relief Request No. RR-38 is authorized for the third 10-year interval of BSEP, Units 1 and 2. All other requirements of the ASME Code,Section XI for which relief has not been specifically requested, remain applicable, including a third party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: Prakash Patnaik Dated: February 12, 2007