ML050490163
| ML050490163 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 03/30/2005 |
| From: | Boska J NRC/NRR/DLPM/LPD1 |
| To: | Kansler M Entergy Nuclear Operations |
| Boska, J, NRC/NRR/DLPM, 301-415-2901 | |
| References | |
| TAC MC2706 | |
| Download: ML050490163 (16) | |
Text
March 30, 2005 Mr. Michael Kansler President Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601
SUBJECT:
PILGRIM NUCLEAR POWER STATION - ISSUANCE OF AMENDMENT RE:
ONE-TIME EXTENSION OF APPENDIX J TYPE A, INTEGRATED LEAKAGE RATE TEST INTERVAL (TAC NO. MC2706)
Dear Mr. Kansler:
The Commission has issued the enclosed Amendment No. 213 to Facility Operating License No. DPR-35 for the Pilgrim Nuclear Power Station. This amendment is in response to your application dated April 14, 2004, as supplemented on November 10, 2004.
This amendment revises Technical Specification (TS) Section 4.7.A.2.a, Primary Containment Integrity, to allow a one-time interval extension of no more than 5 years for the Type A, Integrated Leakage Rate Test.
A copy of the related Safety Evaluation is also enclosed. Notice of Issuance will be included in the Commission's biweekly Federal Register Notice.
Sincerely,
/RA/
John P. Boska, Senior Project Manager, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-293
Enclosures:
- 1. Amendment No. 213 to License No. DPR-35
- 2. Safety Evaluation cc w/encls: See next page
Mr. Michael Kansler President Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601
SUBJECT:
PILGRIM NUCLEAR POWER STATION - ISSUANCE OF AMENDMENT RE:
ONE-TIME EXTENSION OF APPENDIX J TYPE A, INTEGRATED LEAKAGE RATE TEST INTERVAL (TAC NO. MC2706)
Dear Mr. Kansler:
The Commission has issued the enclosed Amendment No. 213 to Facility Operating License No. DPR-35 for the Pilgrim Nuclear Power Station. This amendment is in response to your application dated April 14, 2004, as supplemented on November 10, 2004.
This amendment revises Technical Specification (TS) Section 4.7.A.2.a, Primary Containment Integrity, to allow a one-time interval extension of no more than 5 years for the Type A, Integrated Leakage Rate Test.
A copy of the related Safety Evaluation is also enclosed. Notice of Issuance will be included in the Commission's biweekly Federal Register Notice.
Sincerely,
/RA/
John P. Boska, Senior Project Manager, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-293
Enclosures:
- 1. Amendment No. 213 to License No. DPR-35
- 2. Safety Evaluation cc w/encls: See next page DISTRIBUTION:
PUBLIC D. Roberts K. Manoli R. Dennig C. Anderson, RI PDI-2 R/F C. Raynor D. Jeng G. Hill (2)
ACRS OGC J. Boska J. Pulsipher R. Palla Accession Number: ML050490163
- SE input provided. No major changes made.
OFFICE PDI-2/PM PDI-2/LA SPSB/SC*
EMEB/SC*
IROB/SC OGC PDI-2/SC NAME JBoska CRaynor RDennig KManoly TTjader for TBoyce TSmith DRoberts DATE 3/18/05 3/18/05 11/19/04 01/21/05 03/08/05 3/28/05 3/29/05 OFFICIAL RECORD COPY
Pilgrim Nuclear Power Station cc:
Regional Administrator, Region I U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406-1415 Senior Resident Inspector U. S. Nuclear Regulatory Commission Pilgrim Nuclear Power Station Post Office Box 867 Plymouth, MA 02360 Chairman, Board of Selectmen 11 Lincoln Street Plymouth, MA 02360 Chairman Nuclear Matters Committee Town Hall 11 Lincoln Street Plymouth, MA 02360 Chairman, Duxbury Board of Selectmen Town Hall 878 Tremont Street Duxbury, MA 02332 Office of the Commissioner Massachusetts Department of Environmental Protection One Winter Street Boston, MA 02108 Office of the Attorney General One Ashburton Place 20th Floor Boston, MA 02108 Director, Radiation Control Program Commonwealth of Massachusetts Executive Offices of Health and Human Services 174 Portland Street Boston, MA 02114 Secretary of Public Safety Executive Office of Public Safety One Ashburton Place Boston, MA 02108 Director, Massachusetts Emergency Management Agency Attn: James Muckerheide 400 Worcester Road Framingham, MA 01702-5399 Mr. William D. Meinert Nuclear Engineer Massachusetts Municipal Wholesale Electric Company P.O. Box 426 Ludlow, MA 01056-0426 Mr. Michael A. Balduzzi Site Vice President Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360-5508 Mr. Stephen J. Bethay Director, Nuclear Assessment Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360-5508 Mr. Bryan S. Ford Manager, Licensing Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360-5508 Mr. David F. Tarantino Nuclear Information Manager Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360-5508
Pilgrim Nuclear Power Station cc:
Mr. Gary J. Taylor Chief Executive Officer Entergy Operations 1340 Echelon Parkway Jackson, MS 39213 Mr. John T. Herron Sr. VP and Chief Operating Officer Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601 Mr. Oscar Limpias Vice President, Engineering Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601 Mr. Brian OGrady Vice President, Operations Support Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601 Mr. John F. McCann Director, Nuclear Safety Assurance Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601 Ms. Charlene D. Faison Manager, Licensing Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601 Mr. Michael J. Colomb Director of Oversight Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601 Mr. John M. Fulton Assistant General Counsel Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601 Ms. Stacey Lousteau Treasury Department Entergy Services, Inc.
639 Loyola Avenue New Orleans, LA 70113 Mr. James Sniezek 5486 Nithsdale Drive Salisbury, MD 21801 Mr. Kenneth L. Graesser 38832 N. Ashley Drive Lake Villa, IL 60046 Mr. Ronald Toole 1282 Valley of Lakes Box R-10 Hazelton, PA 18202 Ms. Deb Katz, Executive Director Nuclear Security Coalition c/o Citizens Awareness Network Box 83 Shelburne Falls, MA 01370
ENTERGY NUCLEAR GENERATION COMPANY ENTERGY NUCLEAR OPERATIONS, INC.
DOCKET NO. 50-293 PILGRIM NUCLEAR POWER STATION AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 213 License No. DPR-35 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment filed by Entergy Nuclear Operations, Inc. (the licensee) dated April 14, 2004, as supplemented on November 10, 2004, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations; B.
The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.
There is reasonable assurance: (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations; D.
The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.
The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.
2.
Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and paragraph 3.B of Facility Operating License No. DPR-35 is hereby amended to read as follows:
B.
Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 213, are hereby incorporated in the license. The licensee shall operate the facility in accordance with the Technical Specifications.
3.
This license amendment is effective as of the date of issuance and shall be implemented within 30 days.
FOR THE NUCLEAR REGULATORY COMMISSION
/RA/
Darrell J. Roberts, Chief, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation
Attachment:
Changes to the Technical Specifications Date of Issuance: March 30, 2005
ATTACHMENT TO LICENSE AMENDMENT NO. 213 FACILITY OPERATING LICENSE NO. DPR-35 DOCKET NO. 50-293 Replace the following pages of the Appendix A Technical Specifications with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.
Remove Insert 3/4.7-4 3/4.7-4 3/4.7-5 3/4.7-5 B 3/4.7-4 B 3/4.7-4
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 213 TO FACILITY OPERATING LICENSE NO. DPR-35 ENTERGY NUCLEAR GENERATION COMPANY ENTERGY NUCLEAR OPERATIONS, INC.
PILGRIM NUCLEAR POWER STATION DOCKET NO. 50-293
1.0 INTRODUCTION
By letter dated April 14, 2004, as supplemented on November 10, 2004, Entergy Nuclear Operations, Inc. (ENO or the licensee) submitted a request for changes to the Pilgrim Nuclear Power Station (PNPS) Technical Specifications (TSs). The requested changes would revise TS Section 4.7.A.2.a, Primary Containment Integrity, to allow a one-time interval extension of no more than 5 years for the Type A, Integrated Leakage Rate Test (ILRT). The November 10, 2004, letter provided clarifying information that did not change the initial proposed no significant hazards consideration determination.
2.0 REGULATORY EVALUATION
Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix J, Option B, requires that a Type A test be conducted at a periodic interval based on historical performance of the overall containment system. PNPS TS 4.7.A.2.a requires that leakage rate testing be performed as required by 10 CFR Part 50, Appendix J, Option B, as modified by Nuclear Regulatory Commission (NRC or the Commission)-approved exemptions, and in accordance with the guidelines contained in Regulatory Guide (RG) 1.163, Performance-Based Containment Leak-Test Program, dated September 1995, with certain exceptions specified in the TS. This RG endorses, with certain exceptions, Nuclear Energy Institute (NEI) report NEI 94-01, Revision 0, Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J, dated July 26, 1995.
A Type A test is an overall (integrated) leakage rate test of the containment structure.
NEI 94-01 specifies an initial test interval of 48 months, but allows an extended interval of 10 years, based upon two consecutive successful tests. There is also a provision for extending the test interval an additional 15 months in certain circumstances. The most recent two Type A tests at PNPS have been successful, so the current interval requirement is 10 years.
The licensee is requesting a change to TS 4.7.A.2.a which would add an exception from the guidelines of RG 1.163 and NEI 94-01, Revision 0, regarding the Type A test interval.
Specifically, the exception states that the first Type A test performed after the May 25, 1995, Type A test shall be performed no later than May 25, 2010.
The local leakage rate tests (Type B and Type C tests), including their schedules, are not affected by this request.
3.0 TECHNICAL EVALUATION
3.1 Containment Integrity PNPS is a General Electric boiling water reactor (BWR)/3 plant with Mark I primary containment. The Mark I primary containment consists of a drywell, which encloses the reactor vessel, reactor coolant recirculation system and branch lines of the reactor coolant system (RCS), a toroidal-shaped pressure suppression chamber containing a large volume of water, and a vent system connecting the drywell to the water space of the suppression chamber. The primary containment is penetrated by access piping, and electrical penetrations.
As stated in its application dated April 14, 2004 (Reference 1), PNPS performed the last three consecutive ILRTs in August 1991, May 1993, and May 1995. Based on the requirements of 10 CFR Part 50, Appendix J, Option B, and in consideration of the three successful Type A tests performed, the current ILRT interval requirement for PNPS is 10 years. With the requested extension of the ILRT time interval, the licensee proposes the next overall verification of the containment leak-tight integrity by May 25, 2010. Because the leak rate testing requirements (ILRTs and local leak-rate tests (LLRTs)) of Option B of 10 CFR Part 50, Appendix J, and the containment inservice inspection (ISI) requirements mandated by 10 CFR 50.55a complement each other in ensuring the leak-tightness and structural integrity of the containment, the NRC staff, from its review of Type A test interval extension applications submitted by other licensees, has identified a number of general areas that the licensee was requested to address in relation to the ISI of the PNPS containment. The areas discussed in the NRC staffs request for additional information (RAI) and evaluation of the PNPSs response are provided below:
Ability to Identify Containment Degradation The licensee stated in Attachment 1 to Reference 1 that past augmented examinations documented corrosion in the drywell to torus main vent low points, which were below minimum wall thickness but were found acceptable by evaluation. The NRC staff requested that ENO describe the basis for its determination that the below-minimum wall thickness is acceptable and to assess the potential impact of the proposed one-time ILRT interval extension upon the licensee's continued ability to timely identify and evaluate containment degradation in order to reasonably assure the leak-tightness and structural integrity of PNPS's containment.
In its response dated November 10, 2004 (Reference 7), ENO indicated that it had performed calculations to determine minimum acceptable thickness for general and localized areas of the containment structure prior to its inspection. The statement in Attachment 1 of the response was in reference to general-area thickness. Inspection of the drywell-to-torus vent line low point bowl regions identified areas of localized pitting. The individual pits were sized and compared to both general-area and local-area minimum wall thickness requirements. The results of this comparison provided the technical basis for ENOs acceptabity finding. The licensee further stated that PNPS is requesting a one-time extension of the ILRT containment pressurization test only. In order to allow for early uncovering of evidence of structural deterioration, PNPS will perform the visual examination of accessible interior and exterior surfaces of the containment system during its 2005 refueling outage (RFO15). The visual examination will also be performed again prior to the ILRT currently planned for the RFO in 2009. Plans call for visual VT-3 reinspection of the vent system locations where coating repairs were made in 1999.
The reinspection would be performed during a detailed visual walkdown scheduled for RFO16 in 2007. Additionally, augmented ultrasonic (UT) examinations of containment wall thickness will continue to be performed of the torus shell in RFO16 (2007), and at selected upper drywell locations in RFO17 (2009). PNPS will continue to perform the Type B and Type C LLRT during the interval extension period. In addition, the primary containment nitrogen makeup quantity will continue to be monitored for any trend that may be indicative of a potential degradation of containment leak-tightness. The NRC staff finds that the licensees proposed additional visual and augmented UT examinations, in conjunction with the continued implementation of the primary containment nitrogen makeup usage monitoring program, are adequate and acceptable to reasonably assure the leak-tightness and structural integrity of the PNPS containment.
Augmented Examination Results The NRC staff also requested that ENO discuss the PNPS containment's key augmented examination results beyond those reported in Section 5.1.3 of Attachment 5 to Reference 1.
This information would provide additional performance-based justifications for the NRC staff's acceptance of the proposed one-time ILRT interval extension.
In Reference 7, ENO responded that, in addition to the inspection results reported in Section 5.1.3 of Attachment 5, augmented UT examinations were conducted in 1999 and 2001 at the 9-, 72-and 83-foot elevations of the drywell shell. These examinations detected no wall loss or evidence of degradation after approximately 28 years of service. Augmented UT examinations at two locations on the 72-foot elevation adjacent to the spent fuel pool (SFP) will continue to be performed once every 10 years in accordance with the PNPS American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) IWE program. The drywell wall thickness measurements are supported by the lack of any leakage detected from the annulus drain lines. Leakage from the refueling bellows when the refueling cavity is flooded or leakage due to SFP leaks would eventually be directed into the annulus drains. Leak checks of the annulus drain lines are performed during each RFO shortly after flooding up to the maximum elevation (116 ft.) and prior to draining down at the end of each outage. The licensee indicated that no leakage has been found coming from an annulus drain. Torus (suppression pool) wall thickness was measured ultrasonically in 1999 and 2003 in four locations near the water line and at an additional four submerged locations. Torus wall thickness was determined to be at nominal wall thickness values. ENO chose these augmented examination locations as the areas most likely to experience degradation due to external corrosion considering the containment design and fabrication methods used during construction at PNPS. The fact that no degradation of the containment was discovered in approximately 28 years since commencing commercial power operations in 1972, provides a performance-based justification for the premise that PNPS's containment structure has not degraded significantly over time and for NRC staff acceptance of a one-time ILRT interval extension. The NRC staff finds the results of augmented examination described in References 1 and 7 reasonable and acceptable. These performance-based results further reinforce ENOs risk-informed justifications presented in of Reference 1.
ISI Program In Reference 7, the licensee further described PNPSs ISI methods and plans for the additional 5-year extended period in order to provide the assurance that, in the absence of an ILRT for 15 years, the containment structural and leak-tight integrity would be maintained. The licensee stated that the first 10-year ASME Code IWE inspection interval ends in September 2008. The second IWE 10-year program examinations will be performed in accordance with requirements as determined by the ASME Code accepted by reference in 10 CFR 50 twelve months prior to the start of the interval. Augmented examination areas will be selected in accordance with ASME Code requirements in effect at that time. The performance of ASME Code-required examinations during the second 10-year interval beginning September 2008, and Appendix J Type B and C tests performed during each RFO, will provide sufficient assurance that containment structural and leak-tight integrity will be maintained for the 2-year period from September 2008 to 2010. The NRC staff finds that the licensees proposed ISI methods and plans for the additional 5-year extended period are consistent with the applicable ASME Code,Section XI, Subsection IWE, requirements and are, therefore, acceptable.
With respect to the examination of seals and gaskets, and examination and testing of bolted connections associated with the primary containment pressure boundary (Examination Categories E-D and E-G), Attachment 5 to Reference 1 discusses related relief requests that granted PNPS relief from the ASME Code's requirements. As an alternative, the licensee proposed to examine these items during the leak-rate testing of the primary containment.
However, Option B of Appendix J for Type B and Type C testing (as per NEI 94-01 and RG 1.163) and the ILRT interval extension requested in Reference 1 for Type A testing, provide flexibility in the scheduling of these inspections. PNPS was requested to provide its schedule for examination and testing of seals, gaskets, and bolts beyond the first 10-year period that would provide assurance regarding the leak tightness and structural integrity of the containment.
The licensee stated in Reference 7 that the current 10-year ILRT interval ends in May 2005, and provided the above-requested information including the currently planned testing for Type B testing of seals, gaskets, and O-Rings in a table. The NRC staff reviewed the table and found information provided in the table adequate and acceptable.
With respect to Information Notice (IN) 92-20, which indicates that stainless steel bellows have been found to be susceptible to trans-granular stress-corrosion cracking (SCC) and the leakage through them is not readily detectable by Type B testing, the NRC staff requested ENO to describe its past experience with respect to PNPSs inspection and testing of bellows, and discuss how such potential SCC behavior has been factored into the risk assessment implemented for justifying the proposed one-time ILRT interval extension.
The licensee stated that IN 92-20 documented that Type B testing performed on two-ply expansion bellows with one pressurization test connection did not detect a through-wall defect that existed downstream of a crimp in the bellows. Due to the crimp in the bellows, the area with the defect did not communicate with the test connection area. PNPSs expansion bellows configuration has two test connections, one on each end of the bellows. As a result of IN 92-20, PNPS performs a flow test across the bellows to verify that the test connections communicate across the entire length of bellows (i.e. the bellows is not crimped), followed by a flow makeup leakage test. Since PNPS's configuration has the two test connections, the potential for undetected potential SCC behavior did not need to be factored into the risk assessment. The NRC staff concurs with the licensees assertion and finds that the response is acceptable for resolving the IN 92-20-related concern.
Age-Related Corrosion Effects In regard to inaccessible areas of the containment liner, for which degradations cannot be detected by visual examinations, the licensee, as discussed in Attachment 4 to Reference 1, performed an ILRT extension risk assessment considering the potential age-related corrosion effects on the containment liner integrity and a series of parametric sensitivity studies. The results of the risk assessment indicated that the ILRT interval extension has a minimal impact on plant risk. From its review of the licensees submittal, the NRC staff finds that the increase in predicted risk due to the proposed change is within the acceptance guidelines while maintaining the defense-in-depth philosophy of RG 1.174, An Approach For Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis. This finding resolves the concern related to the aging and degradation of liners located in inaccessible areas of the containment.
On the basis of its review of the information provided by the licensee in the TS amendment request and the licensees response to the NRC staffs RAI (Reference 7), the NRC staff finds that (1) the structural integrity of the containment vessel is verified through the periodic ISIs conducted as required by Subsection IWE of the ASME Code,Section XI, and (2) the integrity of the penetrations and containment isolation valves are periodically verified through Type B and Type C tests as required by 10 CFR Part 50, Appendix J. In addition, the system pressure tests for containment pressure boundary (i.e., Appendix J tests, as applicable) are required to be performed following repair and replacement activities, if any, in accordance with Article IWE-5000 of the ASME Code,Section XI.
3.2 Type A Test Interval Risk Assessment The licensee has performed a risk impact assessment of extending the Type A test interval to 15 years. The risk assessment was provided in the April 14, 2004, application for license amendment. In performing the risk assessment, the licensee considered the guidelines of NEI 94-01, the methodology used in Electric Power Research Institute (EPRI) TR-104285, Risk Impact Assessment of Revised Containment Leak Rate Testing, and RG 1.174.
The basis for the current 10-year test interval is provided in Section 11.0 of NEI 94-01, Revision 0, and was established in 1995 during the development of the performance-based Option B to Appendix J. Section 11.0 of NEI 94-01 states that NUREG-1493, Performance-Based Containment Leak-Test Program, provided the technical basis to revise leakage rate testing requirements contained in Option B to Appendix J. The basis consisted of qualitative and quantitative assessments of the risk impact (in terms of increased public dose) associated with a range of extended leakage rate test intervals. To supplement this basis, industry undertook a similar study. The results of that study are documented in EPRI Research Project Report TR-104285.
The EPRI study used an analytical approach similar to that presented in NUREG-1493 for evaluating the incremental risk associated with increasing the interval for Type A tests. The Appendix J, Option A, requirements that were in effect for PNPS early in the plants life required a Type A test frequency of three tests in 10 years. The EPRI study estimated that relaxing the test frequency from three tests in 10 years to one test in 10 years would increase the average time that a leak that was detectable only by a Type A test goes undetected from 18 to 60 months. Since Type A tests only detect about 3 percent of the leaks (the rest are identified during local leak-rate tests based on industry leakage rate data gathered from 1987 to 1993),
this results in a 10-percent increase in the overall probability of leakage. The risk contribution of pre-existing leakage for the pressurized water reactor and BWR representative plants in the EPRI study confirmed the NUREG-1493 conclusion that a reduction in the frequency of Type A tests from three tests in 10 years to one test in 20 years leads to an imperceptible increase in risk that is on the order of 0.2 percent and a fraction of one person-rem per year in increased public dose.
Building upon the methodology of the EPRI study, the licensee assessed the change in the predicted person-rem per year frequency. The licensee quantified the risk from sequences that have the potential to result in large releases if a pre-existing leak were present. Since the Option B rulemaking was completed in 1995, the staff issued RG 1.174 on the use of probabilistic risk assessment (PRA) in evaluating risk-informed changes to a plants licensing basis. The licensee has proposed using RG 1.174 guidance to assess the acceptability of extending the Type A test interval beyond that established during the Option B rulemaking.
RG 1.174 defines very small changes in the risk-acceptance guidelines as increases in core damage frequency (CDF) less than 10-6 per year and increases in large early release frequency (LERF) less than 10-7 per year. Since the Type A test does not impact CDF, the relevant criterion is the change in LERF. The licensee has estimated the change in LERF for the proposed change and the cumulative change from the original frequency of three tests in a 10-year interval. RG 1.174 also discusses defense-in-depth and encourages the use of risk analysis techniques to help ensure and show that key principles, such as the defense-in-depth philosophy, are met. The licensee estimated the change in the conditional containment failure probability for the proposed change to demonstrate that the defense-in-depth philosophy is met.
The licensee provided its analyses, as discussed below. The following comparisons of risk from a change in test frequency from three tests in 10 years to one test in 15 years are considered to be bounding for PNPS comparative frequencies of one test in 10 years to one test in 15 years. The following conclusions can be drawn from the analysis associated with extending the Type A test frequency:
1.
Given the change from a three in 10-year test frequency to a one in 15-year test frequency, the increase in the total integrated plant risk is estimated to be less than 0.01 person-rem per year. This increase is comparable to that estimated in NUREG-1493, where it was concluded that a reduction in the frequency of tests from three in 10 years to one in 20 years leads to an imperceptible increase in risk. Therefore, the increase in the total integrated plant risk for the proposed change is considered small and supportive of the proposed change.
2.
The increase in LERF resulting from a change in the Type A test frequency from the original three in 10 years to one in 15 years is estimated to be 4.7 x 10-9 per year based on the internal events PRA, and 2.6 x 10-7 per year including both internal and external events. However, there is some likelihood that the flaws in the containment estimated as part of the Class 3b frequency would be detected as part of the IWE/IWL visual examination of the containment surfaces (as identified in ASME Code,Section XI, Subsections IWE/IWL). Visual inspections are expected to be effective in detecting large flaws in the visible regions of containment, and this would reduce the impact of the extended test interval on LERF. The licensees risk analysis considered the potential impact of age-related corrosion/degradation in inaccessible areas of the containment liner on the proposed change. The increase in LERF associated with corrosion events is estimated to be less than 1 x 10-8 per year.
When the calculated increase in LERF is in the range of 10-7 per year to 10-6 per year, applications are considered if the total LERF is less than 10-5 per year. The licensee estimates that the total LERF for internal and external events is approximately 7 x 10-6 per year. This is based on a judgement that about 10 percent of the external event CDF would contribute to LERF. The NRC staff concludes that increasing the Type A interval to 15 years results in only a small change in LERF and is consistent with the acceptance guidelines of RG 1.174.
3.
RG 1.174 also encourages the use of risk analysis techniques to help ensure and show that the proposed change is consistent with the defense-in-depth philosophy.
Consistency with the defense-in-depth philosophy is maintained if a reasonable balance is preserved between prevention of core damage, prevention of containment failure, and consequence mitigation. The licensee estimates the change in the conditional containment failure probability to be an increase of less than 0.1 percentage point for the cumulative change of going from a test frequency of three in 10 years to one in 15 years. The NRC staff finds that the defense-in-depth philosophy is maintained based on the small magnitude of the change in the conditional containment failure probability for the proposed amendment.
Based on these conclusions, the NRC staff finds that the increase in predicted risk due to the proposed change is within the acceptance guidelines, while maintaining the defense-in-depth philosophy of RG 1.174 and, therefore, is acceptable.
3.3 Editorial Changes TS 4.7.A.2.a has a footnote that currently states, Definition 1.U is not applicable to Leak Rate Tests. Due to other TS changes, the designation 1.U is obsolete. Definition 1.U was the designation for the definition for Surveillance Frequency. The licensee is requesting that the footnote be changed to the following: The definition of Surveillance Frequency is not applicable to Leak Rate Tests. The NRC staff finds this correction to be appropriate and acceptable.
The licensee is also requesting some minor reformatting and, in TS 4.7.A.2.a.3.4, the insertion of the word where. The NRC staff finds these clarifying changes to be acceptable.
3.4 NRC Staffs Conclusion Based on its review, the NRC staff finds that the interval between Type A containment ILRT tests at PNPS may be extended to 15 years, and that the proposed changes to TS 4.7.A.2.a, including the editorial changes, are acceptable.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Massachusetts State Official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (69 FR 62473). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
7.0 REFERENCES
1.
Letter from Michael A. Balduzzi of ENO, to NRC, Request for Amendment to the Technical Specifications to Provide a One-Time Integrated Leak Rate Test (ILRT)
Interval Extension, dated April 14, 2004.
2.
RG 1.174, Rev. 1, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions On Plant-Specific Changes to the Licensing Basis, June 2002.
3.
Amendment No. 167 to PNPS Facility Operating License No. DPR-35 (Tac No. M95326).
4.
RG 1.163, Performance-Based Containment Leak-Test Program. February 1995.
5.
NEI 94-01, Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50 Appendix J.
6.
ANSI/ANS 56.8 - 1994, Containment System Leakage Testing Requirements.
7.
Letter from Michael A. Balduzzi of ENO to NRC, Response to NRC Request for Additional Information on Pilgrim Request for Amendment to Provide a One-Time Integrated Leak Rate Test Interval Extension (TAC No. MC2706), dated November 10, 2004 Principal Contributors: D. Jeng R. Palla J. Pulsipher Date: March 30, 2005