ML082120098
| ML082120098 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 07/29/2008 |
| From: | Cowan P Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC MD7386, TAC MD7387 | |
| Download: ML082120098 (5) | |
Text
10 CFR 50.90 July 29, 2008 U.S. Nuclear Regulatory Commission AnN: 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:
References:
Response to Request for Additional Information Proposed Changes to Technical Specifications Surveillance Requirement 4.4.1.2 - Jet Pumps 1.
Letter from Pamela B. Cowan, Exelon Generation Company, LLC, to U.S. Nuclear Regulatory Commission, "License Amendment Request, Proposed Changes to Technical Specifications Surveillance Requirement 4.4.1.2 - Jet Pumps," dated November 13, 2007.
2.
Letter from Peter J. Bamford, U.S. Nuclear Regulatory Commission, to Charles. G.
Pardee, Exelon Generation Company, LLC, "Limerick Generating Station, Unit Nos. 1 and 2 - Request for Additional Information Regarding Proposed Jet Pump Surveillance Changes (TAC Nos. MD7386 and MD7387)," dated June 20,2008.
In Reference 1, Exelon Generation Company, LLC (Exelon) submitted a license amendment request (LAR) regarding removal of footnotes associated with Surveillance Requirement (SR) 4.4.1.2 contained in the Technical Specifications (TS), Appendix A of Facility Operating License Nos. NPF-39 and NPF-85 for Limerick Generating Station (LGS), Units 1 and 2, respectively.
The footnotes require that original plant startup data be used as a baseline for evaluating the performance of the jet pumps during surveillances required by TS SR 4.4.1.2.
In Reference 2, the NRC requested additional information in order to complete its review of the LAR. Attachment 1 to this letter provides a restatement of the questions along with Exelon's response.
Response to Request for Additional Information License Amendment Request Proposed Changes to TS SR 4.4.1.2 - Jet Pumps Docket Nos. 50-352 and 50-353 July 29,2008 Page 2 Exelon has determined that the information provided in response to this request for additional information does not impact the conclusions of the no significant hazards consideration as stated in Reference 1.
If you have any questions or require additional information, please contact Glenn Stewart at 610-765-5529.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 29th day of JUly, 2008.
Respectfully, Pamela B. Cowan Director, Licensing and Regulatory Affairs Exelon Generation Company, LLC
Attachment:
Response to Request for Additional Information cc:
Regional Administrator - NRC Region I NRC Senior Resident Inspector - Limerick Generating Station NRC Project Manager, NRR - Limerick Generating Station Director, Bureau of Radiation Protection - Pennsylvania Department of Environmental Protection wi attachment II
Page 1 of 3 ATTACHMENT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED CHANGES TO TECHNICAL SPECIFICATIONS SURVEILLANCE REQUIREMENT 4.4.1.2 - JET PUMPS LIMERICK GENERATING STATION, UNIT NOS. 1 AND 2 DOCKET NOS. 50-352 AND 50-353 In Reference 1, Exelon Generation Company, LLC (Exelon) submitted a license amendment request (LAR) regarding removal of footnotes associated with Surveillance Requirement (SR) 4.4.1.2 contained in the Technical Specifications (TS), Appendix A of Facility Operating License Nos. NPF-39 and NPF-85 for Limerick Generating Station (LGS), Units 1 and 2, respectively.
The footnotes require that original plant startup data be used as a baseline for evaluating the performance of the jet pumps during surveillances required by TS SR 4.4.1.2.
In Reference 2, the NRC requested additional information in order to complete its review of the LAR. The questions are restated below along with Exelon's response.
1.)
The LAR, Section 4.0, states, "A determination will be made whether or not to change the existing criteria." On what basis will the determination to re-baseline be made? If there is an approved topical report that will be utilized, please identify the document. If the criteria used to make a re-baseline determination is specific to Limerick Generating Station (LGS), please provide a summary of the methodology.
Response
There is no specific NRC-approved topical report that LGS would utilize for re-baselining of the jet pump operability curves. The determination for re-baselining will be consistent with General Electric (GE) Services Information Letter SIL-330 (Reference 3), which was evaluated by the NRC for acceptability for close out of IE Bulletin 80-07 (Reference 4) as documented in NUREG/CR-3052 (Reference 5). For example, re-baselining would be initiated for the following reasons:
- 1. Jet pump maintenance that results in an expected change in jet pump flow characteristics, including, but not limited to: new jet pump installation, disassembly of a jet pump, and jet pump cleaning.
- 2. Following a refueling outage where core changes affecting core flow characteristics are performed, such as, fuel design changes (e.g., installation of fuel that has a different design or has been manufactured by a different fuel supplier). The need to submit a Startup Report required by TS Section 6.9.1.1 due to modifications that may have significantly altered the hydraulic performance of the unit would be indicative of the need to re-baseline.
- 3. Upon entry into single recirculation loop operation (SLO), which is outside of previously operated SLO ranges.
- 4. Operations significantly outside the normal operating range (e.g., operation on the 75% rod line).
2.)
In order to ensure that a re-baseline appropriately reflects the changes in core hydraulics due to refueling activities or configuration changes as described in the LAR, are inspections of the jet pump assemblies performed prior to a planned re-baseline? If they
Response to Request for Additional Information License Amendment Request Page 2 of 3 Proposed Changes to TS SR 4.4.1.2 - Jet Pumps Docket Nos. 50-352 and 50-353 are planned, please provide a summary of these inspection activities. If not, provide a justification as to why they would not be required.
Response
A complete inspection of all jet pump assemblies will not typically be performed prior to re-baselining the jet pump operability curves. Jet pump inspections are performed during refueling outages in accordance with NRC-approved guidelines provided by the Boiling Water Reactor Vessel and Internals Project (BWRVIP). In particular, jet pump inspections are performed in accordance with BWRVIP-41 (Reference 6). BWRVIP-41 provides generic guidelines intended to present the appropriate inspection and flaw evaluation recommendations to assure continued integrity of all jet pump safety functions and to maintain the design basis of jet pump assemblies. These guidelines consider degradation susceptibility, degradation mechanisms, loads, and inspection strategies for jet pump assemblies. BWRVIP-41 inspections include, as appropriate: (1) visual examinations of the jet pump riser welds, diffuser welds, adapter welds, restrainer bracket welds, mixer welds, riser brace welds, main wedges, and (2) ultrasonic testing (UT) of the hold down beams. These exams are performed on a sampling basis in accordance with the frequency specified in BWRVIP-41. If one or more flaws (cracks, wear, bolt loosening, etc.) are found during either the baseline inspection or re-inspection of a specific location, all of the remaining locations of the same type (i.e., all locations with the same number/ID) on all other jet pumps are inspected during the same refueling outage unless the flaw can be correlated to a specific event. The purpose of this scope expansion is to assure that, for those degraded locations, inspections are completed so that any generic degradation can be identified. In addition, the effect that degradation of one location has on another location is considered when determining if additional scope expansion is warranted. BWRVIP-41 was approved by the NRC by Final Safety Evaluation dated February 4, 2001 (Reference 7), in which the NRC concluded that implementation of the BWRVIP-41 guidelines provides an acceptable level of quality for inspection and flaw evaluation of jet pump assemblies.
Similar to BWRVIP-41, BWRVIP-48-A (Reference 8), also approved by the NRC, requires a visual inspection of the attachment welds of the jet pump riser brace leaves to the reactor vessel wall. These attachment welds are typically inspected each outage on a sampling basis as well. The examinations performed in accordance with BWRVIP-41 and BWRVIP-48-A ensure that the structural integrity of all jet pump assemblies is maintained throughout the operating cycle. Limerick will continue to evaluate and implement, as appropriate, any future revisions and subsequent correspondence associated with these guidelines.
3.)
How will the re-baseline criteria/inspection plans be controlled?
Response
BWRVIP inspection requirements are controlled in accordance with Exelon administrative procedures. The re-baseline criteria will be captured in a new station-specific procedure.
The results of the re-baselining may change acceptance criteria for the existing daily jet
Response to Request for Additional Information License Amendment Request Page 3 of 3 Proposed Changes to TS SR 4.4.1.2 - Jet Pumps Docket Nos. 50-352 and 50-353 pump operability surveillances. Changes to surveillance test acceptance criteria are subject to review in accordance with the requirements of 10CFR50.59.
4.)
The existing wording in the LGS TSs is unusual as compared to other similar Boiling Water Reactors (BWRs). Is there anything specific to the LGS design or operation that would differentiate it from other similar BWRs with respect to the baseline for jet pump surveillance acceptance criteria?
Response
The jet pumps at LGS are a standard General Electric BWR/4 design with the exception that the jet pumps at LGS do not provide a flow path for Low Pressure Coolant Injection (LPCI) flow into the reactor core. At LGS, LPCI flow is injected directly into the core shroud through separate LPCI nozzles. There is nothing specific to the LGS jet pump design or operation that would differentiate it from other similar BWRs or require that startup test data specifically be used as the baseline acceptance criteria for jet pump surveillances.
References
- 1. Letter from Pamela B. Cowan, Exelon Generation Company, LLC, to U.S. Nuclear Regulatory Commission, "License Amendment Request, Proposed Changes to Technical Specifications Surveillance Requirement 4.4.1.2 - Jet Pumps," dated November 13, 2007.
- 2. Letter from Peter J. Bamford, U.S. Nuclear Regulatory Commission, to Charles. G. Pardee, Exelon Generation Company, LLC, "Limerick Generating Station, Unit Nos. 1 and 2 -
Request for Additional Information Regarding Proposed Jet Pump Surveillance Changes (TAC Nos. MD7386 and MD7387)," dated June 20, 2008.
- 3. General Electric (GE) Service Information Letter (SIL) No. 330, "Jet Pump Beam Cracks,"
dated June 9, 1980.
- 4. IE Bulletin 80-07, "BWR Jet Pump Assembly Failure," dated April 4, 1980.
- 5. NUREG/CR-3052, "Closeout of IE Bulletin 80-07: BWR Jet Pump Assembly Failure,"
published November 1984.
- 6. BWRVIP-41, "BWR Vessel and Internals Project, BWR Jet Pump Assembly Inspection and Flaw Evaluation Guidelines," dated October 1997, as supplemented by letters dated August 4, 1999 and November 17, 2000.
- 7. Letter dated February 4, 2001, from J. R. Strosnider, USNRC, to C. Terry, BWRVIP Chairman, "Final Safety Evaluation of the 'BWR Vessel and Internals Project, BWR Jet Pump Assembly Inspection and Flaw Evaluation Guidelines (BWRVIP-41),' (TAC No.
M99870)."
- 8. BWRVIP-48-A, "BWR Vessel and Internals Project, Vessel ID Attachment Weld Inspection and Flaw Evaluation Guidelines (BWRVIP-48)," dated June 2004.