ML103510026
| ML103510026 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 12/15/2010 |
| From: | Cowan B Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML103510026 (8) | |
Text
Exelon Nuclear www.exeloncorp.com Exelkn.
200 Exelon Way Nuclear Kennett Square, PA 19348 10 CFR 50.90 December 15, 2010 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Limerick Generating Station, Units 1 and 2 Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353
Subject:
Response to Request for Additional Information Regarding Proposed Technical Specification Changes to High Pressure Coolant Injection Equipment Room Delta Temperature Trip Setpoint and Allowable Value.
References:
- 1. Letter from P. B. Cowan, Exelon Generation Company, LLC, to U.S. Nuclear Regulatory Commission, "License Amendment Request Table 3.3.2-2, Item 4e, HPCI Equipment Room Delta Temperature High Isolation Trip Setpoint and Allowable Value Change," dated June 30, 2010.
- 2. Letter from Peter Bamford, U.S. Nuclear Regulatory Commission, to Michael J. Pacilio, President and Chief Nuclear Officer, Exelon Nuclear, "Limerick Generating Station, Units 1 and 2 - Request for Additional Information Regarding Proposed Technical Specification Changes to High Pressure Coolant Injection Equipment Room Delta Temperature Trip Setpoint and Allowable Value (TAC Nos. ME4171 and ME4172)," dated November 24, 2010.
In Reference 1, Exelon Generation Company, LLC (Exelon) submitted a request for an amendment to the Technical Specifications (TS), Appendix A of Facility Operating License Nos.
50-352 and 50-353 for Limerick Generating Station, Units 1 and 2 (LGS). The proposed amendment would revise the Technical Specification (TS) High Pressure Coolant Injection (HPCI) Equipment Room Delta Temperature High Trip Setpoint and Allowable Value listed in Table 3.3.2-2, Isolation Actuation Instrumentation Setpoints, Item 4e for LGS. The Trip Setpoint and Allowable Value are proposed to be lowered, which is in the conservative direction, to reflect a revised analysis for the HPCI equipment room temperature following a postulated 25 gallon per minute steam leak. The NRC reviewed the license amendment request and identified the need for additional information in order to complete their evaluation of the amendment request. A request for additional information (RAI) was transmitted to Exelon on November 24, 2010 (Reference 2). Attachment 1 to this letter provides a restatement of the RAI along with Exelon's response. Attachment 2 contains the Loop Uncertainty Calculation TE-055-1 N028B.
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U.S. Nuclear Regulatory Commission Docket Nos. 50-352 and 50-353 December 15, 2010 Page 2 Exelon has concluded that the information provided in this response does not impact the conclusions of the: 1) Technical Evaluation, 2) No Significant Hazards Consideration under the standards set forth in 10 CFR 50.92(c), or 3) Environmental Consideration as provided in the original submittal (Reference 1).
This response to the request for additional information contains no regulatory commitments.
If you have any questions or require additional information, please contact Frank Mascitelli at 610-765-5512.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 15 th day of December 2010.
Respectfully, Pamela B. Cowan Director, Licensing and Regulatory Affairs Exelon Generation Company, LLC Attachments: 1-Response to Request for Additional Information 2-Loop Uncertainty Calculation TE-055-1 N028B, dated 11/20/09 cc: Regional Administrator - NRC Region I w/attachments NRC Senior Resident Inspector - LGS NRC Project Manager, NRR - LGS Director, Bureau of Radiation Protection - PA Department of Environmental Resources
U.S. Nuclear Regulatory Commission Docket Nos. 50-352 and 50-353 December 15, 2010 Page 3 bcc: Sr. Vice President, Mid-Atlantic Operations w/o attachments II Sr. Vice President, Operations Support Site Vice President, LGS Plant Manager - LGS Director, Site Operations - LGS Director, Site Engineering - LGS Director, Site Maintenance - LGS Director, Site Training - LGS Director, Licensing - KSA 3-E Manager - Regulatory Assurance - LGS F. J. Mascitelli, KSA 3-E w/ attachments R. W. Harding - LGS K. B. Collier- LGS G. T. Hooper - LGS K. D. Slough III - LGS R. T. George - LGS W. R. Lewis Nuclear Oversight Manager - LGS Commitment Coordinator - KSA 3-E Records Management - KSA 1-N-1
ATTACHMENT 1 Limerick Generating Station Docket Nos. 50-352 and 50-353 License Amendment Request Regarding TS Table 3.3.2-2, Item 4e, HPCI Equipment Room Delta Temperature High Isolation Trip Setpoint and Allowable Value Change Response to Request for Additional Information
Response to RAI Regarding Proposed TS Changes to HPCI Equipment Room Delta Temperature Trip Setpoint and Allowable Value Docket Nos. 50-352 and 50-353 Attachment 1 December 15, 2010 Page 1 of 4 By letter dated June 30, 2010 (Agency wide Documents Access and Management System (ADAMS) Accession No. ML101810434), Exelon Generation Company, LLC (Exelon) submitted a license amendment request (LAR) proposing to revise the Technical Specification (TS) High Pressure Coolant Injection (HPCI) Equipment Room Delta Temperature High Trip Setpoint and Allowable Value listed in Table 3.3.2-2, Isolation Actuation Instrumentation Setpoints, Item 4e, for Limerick Generating Station (LGS), Units 1 and 2 (Reference 1). The Trip Setpoint and Allowable Values are proposed to be lowered, which is in the conservative direction, to reflect a revised analysis for the HPCI equipment room temperature following a postulated 25 gallon per minute steam leak. The Nuclear Regulatory Commission (NRC) staff has been reviewing the submittal and has determined that additional information is needed to complete its review (Reference 2).
The questions are restated below along with Exelon's response:
1.) The LAR, Attachment 1, "Evaluation of Proposed Technical Specifications Changes,"
pages 4 and 5, outlines the loop uncertainty calculation, but does not provide the basis for all the numbers used in the calculation. In order for the NRC staff to verify the acceptability of the setpoint analysis, please provide the complete calculation, indicated as "Reference 6 - Loop Uncertainty Calculation TE-055-1 N028B." If the basis for all numbers used in the loop uncertainty calculation is not contained in TE-055-1 N028B, please provide that information separately.
Response
The complete calculation, Loop Uncertainty Calculation TE-055-1 N028B, dated 11/20/09 (Reference 3), is provided as Attachment 2 to this response.
2.) The LAR, Attachment 1, pages 5 and 6, outlines instrument channel operability. For license amendment reviews, the NRC staff uses the terms As-Left and As-Found tolerances, Allowable Value, and Analytical Limit, which are all described in Regulatory Issue Summary (RIS) 2006-17, "NRC Staff Position on the Requirements of 10 CFR 50.36, 'Technical Specifications,' Regarding Limiting Safety System Settings During Periodic Testing and Calibration of Instrument Channels." From the description in the submittal, it is unclear how the "Leave Alone Zone" (LAZ) is used or treated in the instrument channel maintenance program. Therefore, please describe how application of the LAZ provides adequate assurance of channel operability. Though not required, it would be helpful to describe the LAZ as it relates to the descriptions in RIS 2006-17.
Response
The leave alone zone (LAZ) is a range of acceptable values around a nominal value established by adding or subtracting the required accuracy during calibration from the nominal value. The required accuracy is the accuracy within which an instrument, or series of instruments, must be demonstrated to perform during calibration activities. The required accuracy is typically considered equal to the reference accuracy of the device under calibration. The required accuracy for a series of instruments calibrated or
Response to RAI Regarding Proposed TS Changes to HPCI Equipment Room Delta Temperature Trip Setpoint and Allowable Value Docket Nos. 50-352 and 50-353 Attachment 1 December 15, 2010 Page 2 of 4 checked together is the Square Root Sum of the Squares (SRSS) combination of the individual instrument required accuracies.
When the As-Found instrument(s) reading is found within this band during surveillance testing or calibration checks, no calibration adjustment is required. If the As-Found instrument reading is found outside this band during surveillance testing or calibration checks, the instrument must be adjusted so that the As-Left instrument reading is within the LAZ. Since the required accuracy, and therefore the LAZ, is based on the reference accuracy of the device under calibration, the LAZ provides adequate assurance that this instrument is performing as expected and the instrument channel is operable. For the purpose of comparison with RIS 2006-17, the LAZ is used in the same manner as the As-Left Tolerance (ALT).
3.) As described in RIS 2006-17, values found outside the As-Found limit are typically entered in the corrective action program (CAP), recalibrated and retested. Also, as described in RIS 2006-17, it is the NRC staff position that verifying the As-Found setpoint is within limits is part of the determination that an instrument is functioning as required. Further, Title 10 of the Code of FederalRegulations Part 50, Appendix B, Criterion XVI, "Corrective Action," requires that significant conditions adverse to quality be promptly identified, corrected, and documented. From the process description in the LAR, it appears that the setpoint can drift up to the Allowable Value and never be entered in the CAP. Please clarify what actions would be taken for setpoints found to exceed the LAZ. If no CAP entry is made for setpoints outside of a pre-established As-Found tolerance band, please justify why this provides acceptable setpoint programmatic controls regarding evaluation, trending, and corrective actions, and explain how this ensures that these instruments are operating in accordance with the assumptions in the governing setpoint analysis.
Response
If the As-Found setpoint is found to exceed acceptable limits (also known as LAZ) and the Allowable Value, the test performer attempts to adjust the setpoint within acceptable limits. If the setpoint can be adjusted within acceptable limits, the test is statused as Fail/Pass. If the setpoint cannot be adjusted within acceptable limits the test is statused as Fail. The test performer also initiates an Issue Report in the CAP in either case.
If the As-Found setpoint is found to exceed acceptable limits but does not exceed the Allowable Value, the test performer attempts to adjust the setpoint within acceptable limits. If the setpoint can be adjusted within acceptable limits, the test is statused as Pass. In these cases the surveillance test coordinator reviews the test for repeat occurrences. If repeat occurrences are identified, the condition is considered for inclusion in the CAP. This provides acceptable programmatic control since the setpoint can be adjusted to within acceptable limits, the instrument(s) is operating within the requirements of the instrument channel and within the allocations of margin for instrument drift. In addition, an allocation of margin for calibration accuracy is provided between the Allowable Value and Analytical Limit. The allocation of this margin assures
Response to RAI Regarding Proposed TS Changes to HPCI Equipment Room Delta Temperature Trip Setpoint and Allowable Value Docket Nos. 50-352 and 50-353 Attachment 1 December 15, 2010 Page 3 of 4 operability of the instrument channel as long as the As-Found setpoint does not exceed the Allowable Value. If the setpoint cannot be adjusted within acceptable limits, the test is statused as Fail and the test performer initiates an Issue Report in the CAP.
4.) The LAR, Attachment 1, page 3, states that the CFLUD program is the same program as was used to support a similar LGS 1995 License Amendment. However, a review of a LGS request for additional information response from the specified 1995 amendment dated September 23, 1994 (ADAMS Legacy Library Accession No. 9409290232), and the NRC safety evaluation for the 1995 amendment dated January 20, 1995 (ADAMS Accession No. MLO1 1560074), indicates that PCFLUD was the computer code used.
The LAR provides a description of certain changes between CFLUD and PCFLUD, however it does not identify how the computer coding changes, if any, were validated.
Please clarify which computer code was used for both the 1995 amendment and the current LAR. If there have been changes to the computer code used to support the current LAR as compared to the 1995 amendment, please describe the steps taken to validate the changes.
Response
The computations of the temperature of the HPCI room following a steam leak prepared in support of the 1995 license amendment were prepared using the CFLUD computer code as was the calculation supporting the current LAR. The statement in the current LAR, Attachment 1, page 3, refers to the computations of room temperature following steam leaks. However, the post LOCA temperature curve for the HPCI pump room supplied in the response to RAI for the 1995 license amendment, included in the letter from PECO Energy to the NRC dated September 23, 1994, was prepared using PCFLUD. This curve was excerpted from Calculation LM-400, rev. 0 prepared in September 1993. The CFLUD computer code was not completed until December 1993.
Both the PCFLUD and CFLUD computer codes were prepared by Bechtel Corporation, under their QA program. The validation and verification of both computer codes was likewise performed by Bechtel in accordance with their software QA program. Validation and verification cases for both programs were supplied to PECO Energy by Bechtel to verify proper installation and operation of the computer codes. Exelon maintains both computer programs under the existing Exelon Software QA program.
REFERENCES:
- 1. Letter from P. B. Cowan, Exelon Generation Company, LLC, to U.S. Nuclear Regulatory Commission, "License Amendment Request Table 3.3.3-2, Item 4e, HPCI Equipment Room Delta Temperature High Isolation Trip Setpoint and Allowable Value Change,"
dated June 30, 2010.
Response to RAI Regarding Proposed TS Changes to HPCI Equipment Room Delta Temperature Trip Setpoint and Allowable Value Docket Nos. 50-352 and 50-353 Attachment 1 December 15, 2010 Page 4 of 4
- 2. Letter from Peter Bamford, U.S. Nuclear Regulatory Commission, to Michael J. Pacilio, President and Chief Nuclear Officer, Exelon Nuclear, "Limerick Generating Station, Units 1 and 2 - Request for Additional Information Regarding Proposed Technical Specification Changes to High Pressure Coolant Injection Equipment Room Delta Temperature Trip Setpoint and Allowable Value (TAC Nos. ME4171 and ME4172),"
dated November 24, 2010.
- 3. Loop Uncertainty Calculation TE-055-1N028B, dated 11/20/09.