ML070580301

Additional Information Concerning Technical Specifications Change Request No. 334 - One-Time Type a Test Interval Extension

ML070580301
Person / Time
Site:	Three Mile Island
Issue date:	02/26/2007
From:	Cowan P B AmerGen Energy Co, Exelon Corp
To:	Document Control Desk, NRC/NRR/ADRO
References
5928-07-20047, RG-1.174
Download: ML070580301 (4)

Text

10 CFR 50.90 5928-07-20047 February 26,2007 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Three Mile Island, Unit 1 Facility Operating License No.

DPR-50 NRC Docket No. 50-289

Subject:

Additional Information Concerning Technical Specifications Change Request No. 334 - One-Time Type A Test Interval Extension

Reference:

1) Letter from P. B. Cowan (AmerGen Energy Company, LLC) to U. S. Nuclear Regulatory Commission, dated September 15, 2006 In the Reference 1 letter, AmerGen Energy Company, LLC (AmerGen) requested an amendment to Appendix A, Technical Specifications, of Facility Operating License No. DPR-50. The proposed change modifies Technical Specifications (TS) 6.8.5, "Reactor Building Leakage Rate Testing Program." Specifically, the proposed change will revise TS 6.8.5 to reflect a one- time extension to the Three Mile Island, Unit 1 Type A Integrated Leak Rate Test (ILRT) interval as currently specified in the Technical Specifications.

As discussed in the Reference 1 letter, this change will extend the requirement to perform the Type A ILRT from the current requirement of "no later than September 2008" to "prior to startup from the TI R18 refueling outage," which is currently scheduled for Fall 2009. This deferral would add approximately 13' months of operational time to the currently approved 15-year interval.

This deferral will allow performance of the Type A ILRT during a planned steam generator replacement outage (T1 R18) in the Fall 2009. The last TMI, Unit 1 Type A test was performed in September 1993. Based on the current wording of TS 6.8.5, the next Type A ILRT test is required to be performed no later than September 2008.

This would result in performing the Type A test at the next scheduled refueling outage, which is TI R17 currently scheduled for Fall 2007; otherwise, a mid-cycle outage in 2008 would be necessary to perform the Type A The Reference 1 letter requested an interval extension of 15 months beyond the currently committed date of September 2008. The risk analysis was also calculated using a 15 month extension.

This was based on the ILRT being performed in December 2009 at the end of the planned steam generator replacement outage. In fact, the requested extension is anticipated to be approximately 13 months since the planned steam generator replacement outage commences in October 2009 and containment integrity is not required during the outage.

1 U.S. Nuclear Regulatory Commission February 26,2007 Page 2 ILRT. Compliance with the current TS would impose an undue burden by requiring performance of the Type A ILRT test in the TI R17 outage (currently scheduled for Fall 2007) prior to the breach in containment required for the 2009 planned steam generator replacement, where an additional containment pressure test would be required. Performing the Type A ILRT following the steam generator replacement will provide a more comprehensive test of the entire containment barrier, including the new steam generator shell and associated connections that form a closed system barrier inside containment, following the significant breach required to support steam generator replacement.

Many containment leakage boundaries are breached during steam generator replacement. Performing the ILRT concurrent with the post-repair pressure test will verify that these boundaries have been restored to a leak tight condition. The Three Mile Island (TMI), Unit 1 specific risk analysis included with the Reference 1 letter provided a conservative estimate of the increased exposure risk associated with deferring the ILRT an additional 15 months.

The following is a brief summary of some of the key aspects of the Type A ILRT test interval extension risk analysis for a one-time increase from 15 years to 16.25 years: o Increasing the current one-time 15-year ILRT interval to 16.25 years results in an insignificant increase in total population dose rate, from 10.750 person-remlyear to 10.768 person-remlyear, respectively.

o The increase in the LERF risk measure, 1 .45E-8/yrI is categorized as a "very small" increase per NRC Regulatory Guide 1.174.

o Likewise, the conditional containment failure probability (CCFP%) increases insignificantly by 0.1 percentage points.

With respect to dose, using current estimates of resources required to perform the integrated leak rate test shows approximately 750 person-hours of work required within containment. Historical effective dose rates in the containment during refueling outages are 0.2 to 0.4 mremlhr. Using an average estimated effective dose rate of 0.3 mrem per hour results in an estimated dose of 0.225 person-rem, or 225 person-mrem to perform the ILRT. Preparing the containment for pressurization, post-pressurization restoration and performing the necessary pre- and post-pressurization examinations to support the pressure testing following steam generator replacement will also involve additional dose. Using current estimates of resources required to perform the pressure test shows approximately 450 person-hours of work required within containment. Using an average estimated effective dose rate of 0.3 mrem per hour results in an estimated dose of 0.135 person-rem, or 135 person-mrem to perform the pressure test. Performing the ILRT concurrent with the post-repair pressure test in 2009 rather than during the 2007 refueling outage will reduce personnel exposure by 135 person-mrem. TMI, Unit 1 will perform a General Visual Examination of the Reactor Building containment liner in accordance with 10 CFR 50.55a(b)(2)(ix)(E) in 2007, prior to the current 15-year ILRT timeframe.

A visual exam of the area adjacent to the moisture barrier (i.e., between liner and concrete) will also be performed this refueling outage. In addition, during the 2007 Refueling Outage, TMI, Unit 1 plans to replace a significant portion of the containment liner moisture U.S. Nuclear Regulatory Commission February 26,2007 Page 3 barrier that has not been replaced in recent outages. The moisture barrier is not a pressure boundary and is installed to protect the metal containment liner from corrosion. Further review of this change has identified an additional burden, which supports the justification for extending the Type A ILRT extension. Specifically, AmerGen began preparation for steam generator replacement in 2004. Pre-construction money was spent prior to a final corporate decision to replace the steam generators. A formal approval was received in 2005 to replace the plant's steam generators to improve the performance of those components along with the decision to pursue license renewal. At that time, the competitive bidding process resulted in a delivery date of mid-2009. From the time the decision was approved in 2005 to install new steam generators, there were only two refueling outages available prior to the Technical Specification required ILRT date of September 2008. Outage planning is a complex task that involves coordinating activities, materials, manpower resources, and outage support contracts. Outage planning is started approximately 23 months prior to a planned refuel outage, and scope and schedule are typically fixed 9 months in advance. Thus, it was not realistic to include an ILRT in the 2005 refuel outage. Including the ILRT in the 2007 outage was considered; however, with the steam generator replacements in 2009, a more efficient approach was to include the ILRT in the 2009 outage.

Additionally, the St. Lucie Plant Unit No. 2 was issued an amendment on December 23, 2005 to extend the ILRT past 15 years due to Steam Generator and Reactor Vessel Head replacement. With an awareness of a similar situation, TMI decided to submit for an extension and include the ILRT in the 2009 outage. The steam generators for TMI are currently under construction and cannot practically be delivered to TMI prior to 2009. At the time of formal approval for construction of the steam generators (2005), AmerGen anticipated that proposed revisions to NEI 94-01 ("Industry Guideline for Implementing Performance-Based Option of 10 CFR 50, Appendix J") would have been completed prior to the 2007 outage, which would have resulted in a 15-month grace to the NEI guidance. AmerGen anticipated that approval of the NEI guidance with a 15-month grace would preclude the need to perform the Type A ILRT in 2005 or 2007. Revisions to the NEI guidance remain in discussion between the industry and NRC. Inability to deliver the steam generators in time for installation during the 7-1 R17 (Fall 2007) outage eliminates our ability to perform the Type A ILRT in accordance with the current Technical Specification timeframe concurrently with the steam generator replacement. Additionally, performing the Type A ILRT, and delaying the installation of the new steam generators for an additional ten (1 0) years would not be feasible in that repeated outage operational assessments have concluded that mid-cycle outages will be necessary following T1 R18 (Fall 2009). Finally, as stated in Reference 1 , this additional containment pressurization test following the steam generator replacement would result in a minimum 21 -hour increase in outage duration and additional direct costs of approximately

$1 50,000 for this outage. This additional test will also result in a cost of approximately

$927,000 for replacement power. Thus, replacement power costs associated with a 21-hour increase in outage duration, plus direct costs associated with the additional containment pressurization test are estimated to be $1,077,000. Costs will also be incurred as a result of administrative costs associated with a second pressurization test and use of TMI inservice inspection manpower to perform the test. Additionally, a number of significant projects are currently scheduled for the Tl R17 refueling outage (steam generator inspections, reactor building sump modifications, Alloy 600 inspections and mitigation, etc.)

US. Nuclear Regulatory Commission February 26,2007 Page 4 which would complicate the performance of the ILRT during this outage as a result of competing resources.

Note that the Reference 1 application complies with the general format for a License Amendment Request to defer the Type A ILRT. In particular, the application is justified through a review of past regulatory history concerning the Type A ILRT, a discussion of plant specific Type A ILRT history, and a review of lnservice Inspection (ISI) results. A Probabilistic Safety Risk Assessment has been performed that demonstrates a very small impact on risk associated with the one time extension of the containment Type A integrated leak rate test (ILRT) interval from 15 years to 16.25 years. Based on the above, considering:

1) the benefit of performing the Type A ILRT concurrently with the planned steam generator replacement;

2) the very small increase in risk; 3) the additional exposure to plant personnel as a result of performing the second pressure test; 4) the scheduling difficulties incurred; and, 5) the additional cost incurred as a result of the additional pressure test, ample hardship has been demonstrated which justifies extending the Type A ILRT as requested in Reference

1. This additional information is bounded by the Reference 1 No Significant Hazards Consideration.

As stated in the referenced submittal, we request your approval by June 30, 2007. If any additional information is needed, please contact Tom Loomis at (61 0) 765-551 0. I declare under penalty of perjury that the foregoing is true and correct. Executed on the 26th day of February, 2007. Respectfully, Pamela B. Cowan Director - Licensing

& Regulatory Affairs AmerGen Energy Company, LLC cc: R. R. Janati, Commonwealth of Pennsylvania S. J. Collins, Administrator, Region 1, USNRC D. M. Kern, USNRC Senior Resident Inspector V. Nerses, Senior Project Manager, USNRC File No. 06050