ML080080456
| ML080080456 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 01/07/2008 |
| From: | Larry Nicholson Tennessee Valley Authority |
| To: | Catherine Haney Plant Licensing Branch III-2 |
| References | |
| TAC MD2980 | |
| Download: ML080080456 (5) | |
Text
January 7, 2008 Ms. Catherine Haney Director, Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Ms. Haney:
In the Matter of )
Docket No. 50-259 Tennessee Valley Authority )
BROWNS FERRY NUCLEAR PLANT (BFN) UNIT 1 - APPLICATION OF PERFORMANCE INDICATORS AND AUGMENTED INSPECTION PROGRAM (TAC NO. MD2980)
This is in response to your December 6, 2007 letter with the subject title. In a letter dated May 16, 2007, NRC outlined the framework for transitioning the three remaining Reactor Oversight Process (ROP) cornerstones (i.e. Initiating Events, Mitigating Systems, and Barrier Integrity) into the full coverage of the ROP. As you indicated, TVA complied with the NRCs request and began reporting data for the Performance Indicators (PI) under these cornerstones by reporting 2nd quarter data before the reporting deadline of July 21, 2007. Regarding the remaining PIs, we would like to address them individually (below) by cornerstone.
Barrier Integrity:
TVA agrees with the conclusions in your letter for the Barrier Integrity PIs (i.e.,
Reactor Coolant System Specific Activity and Reactor Coolant System Leakage).
In fact, on the NRC public website, a color was assigned to these PIs (Green) for the data reported in the 3rd Quarter 2007.
Initiating Events:
For the Unplanned Scrams with Complications PI, TVA agrees with your position.
Again, it is noteworthy that on the NRC public website, a color (Green) was assigned to this PI for the 3rd quarter of 2007.
U. S. Nuclear Regulatory Commission Page 2 January 7, 2008 For the Unplanned Scrams per 7,000 Critical Hours (Unplanned Scrams) and Unplanned Power Changes per 7,000 Critical Hours (Unplanned Power Changes) PIs, TVA recognizes that NRC has decided that the PI should be effective after two full quarters of operation. Browns Ferry Unit 1 started up during the 2nd Quarter of 2007 (i.e., May 2007). Therefore, we understand that these PIs will be considered valid starting with the reporting of the data for the 4th Quarter 2007.
TVA is concerned with the generic implications of considering these PIs valid after two full quarters of operation as this interpretation might apply to other plants in the future. These PIs are rate indicators based on a four-quarter period; therefore, implementing them in less than four quarters can result in misleadingly high values.
Consequently, inappropriate regulatory actions may occur.
TVA performed an informal review of the effect of shortening the Unplanned Scrams PI to a two quarter indicator. The review used data elements reported to Consolidated Data Entry throughout the history of the ROP PI program. The review showed several interesting results, including:
(1) To date, there have been no yellow PIs reported for the Unplanned Scrams PI.
Shortening the period to two quarters would have resulted in about seventeen plants with yellow Unplanned Scram PIs. Almost half of those actually had green PIs throughout the four-quarter period calculating the PI as a 4-quarter indicator; (2) Approximately 160 plants that properly reported green PIs as a 4-quarter indicator would have reported as white indicators if counted as valid for only two quarters of operation.
TVA suggests that NRC and NEI work to resolve this issue on a generic basis for consideration of plants restarting from lengthy outages or experiencing initial startup.
Mitigating Systems:
For the Safety System Functional Failure PI, we agree with your position.
The remaining PIs in the Mitigating Systems Cornerstone are the Mitigating Systems Performance Index (MSPI) PIs for:
- Emergency AC Power System
- High Pressure Injection System
U. S. Nuclear Regulatory Commission Page 3 January 7, 2008
- Residual Heat Removal System
- Cooling Water Support System In response to NRCs request to provide an applicable bases and schedule for integrating Unit 1 MSPI monitoring systems into the ROP, TVA made a good-faith effort to determine a basis, a methodology, and a schedule for activating the MSPI indicators ahead of the 12-quarter period.
TVA assembled a team of individuals from other TVA plants, Corporate, and Browns Ferry to consider options. TVA consulted members of the industry ROP task force (including the industry MSPI experts), and to date, we have not been able to identify a methodology for reporting a MSPI value for these systems through CDE that would have the requisite integrity to allow NRC to base decisions for oversight of these systems.
TVA also consulted with INPO regarding the changes to the CDE software program that would be required to facilitate having CDE calculate and report a MSPI value for any of the systems. INPO representatives indicated that the type of changes that would be required would be extensive and cost prohibitive. As an example, they compared the changes that would be needed for Browns Ferry Unit 1 to changes that they are in the process of making for several plants to more accurately model their plant configuration (e.g., trains, segments, etc.). They indicated that the changes for Browns Ferry would likely be an order of magnitude greater in complexity (and therefore cost and resources). While the changes for these other plants are for the purpose of allowing the indicators to more accurately reflect the plant configurations and would be effective for the remaining lifetime of the plants, the changes for Browns Ferry 1 would result in a recognized less-accurate indicator and would be for the purpose of a short-term compensatory action until valid, plant-specific PIs could be calculated.
INPO has taken great care to maintain CDE as a qualified, validated software package.
The type of changes to CDE that would be required to force it to calculate MSPI values without requisite data could challenge CDEs qualified status.
Notwithstanding the limitation associated with implementing a customized MSPI for Browns Ferry Unit 1, TVA is committed to monitoring the performance of these important systems and taking corrective actions when necessary. To assist TVA in this matter, an approximated MSPI will be generated using a plant-specific calculator (Excel spreadsheet) supplemented with Browns Ferry Unit 2 data.
U. S. Nuclear Regulatory Commission Page 4 January 7, 2008 Although the limitations of this technique are recognized, if the approximated MSPI value derived from the calculator crosses a PI threshold, Browns Ferry will generate a Corrective Action Program (CAP) document and perform an appropriate causal determination.
TVAs actions to monitor the systems, in conjunction with additional NRC inspections under NRC Inspection Manual Chapter 2509, Browns Ferry Unit 1 Restart Project Inspection Program, should, in combination, ensure that NRCs regulatory oversight remains sufficient to independently monitor and evaluate the availability, reliability, and capability of these important mitigating systems.
TVA will continue to report Browns Ferry Unit 1 data as described in NRC IMC 0608 and NEI 99-02. When a plant specific baseline is calculated by the CDE software after 12 quarters of reporting (commencing with 3rd quarter of 2007, as directed by NRCs May 16, 2007 letter), a valid MSPI value for each MSPI PI will be generated by CDE. TVA will be ready to support inspection of MSPI in the 3rd quarter of 2010.
TVA welcomes the opportunity to meet with the NRC and discuss any issues associated with application of PIs to Browns Ferry Unit 1. If you have any questions, please contact me at (423) 751-4877.
Sincerely, Original signed by Larry E. Nicholson, General Manager, Performance Improvement cc: See page 5
U. S. Nuclear Regulatory Commission Page 5 January 7, 2008 Mr. James W. Anderson U. S. Nuclear Regulatory Commission 11 A11 One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2739 Ms. Eva A. Brown, Project Manager U. S. Nuclear Regulatory Commission MS 08G9 One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2739 Mr. Frederick D. Brown U. S. Nuclear Regulatory Commission MS 12 D3 One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2739 NRC Senior Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611-6970