RS-11-153, Response to Request for Additional Information Regarding Unit 2 Spent Fuel Pool Storage Racks
| ML112650186 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 09/21/2011 |
| From: | Simpson P Exelon Generation Co, Exelon Nuclear |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RS-11-153 | |
| Download: ML112650186 (4) | |
Text
Nuclear Exelon Generation Company, LLC www.exeloncorp.com 4300 Winfield Road Warrenville, IL 60555 RS-11-153 September 21, 2011 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 LaSalle County Station, Units 1 and 2 Facility Operating License Nos. NPF-1 1 and NPF-1 8 NRC Docket Nos. 50-373 and 50-374
Subject:
Response to Request for Additional Information Regarding Unit 2 Spent Fuel Pool Storage Racks
References:
1.
Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S. NRC, "License Amendment Regarding the Use of Neutron Absorbing Inserts in Unit 2 Spent Fuel Pool Storage Racks," dated October 5, 2009 2.
Letter from E. A. Brown (U.S. NRC) to M. J. Pacilio (Exelon Nuclear),
"LaSalle County Station, Units 1 and 2, Issuance of Amendments Concerning Spent Fuel Neutron Absorbers (TAC Nos. ME2376 and ME2377)
(RS-09-133)," dated January 28, 2011 3.
Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S. NRC, "Completion of Licensing Condition 2.C.(30) Associated with Unit 2 Spent Fuel Pool Storage Racks," dated July 13, 2011 4.
Letter from A. T. Billoch Colon (U.S. NRC) to M. J. Pacilio (Exelon Nuclear),
"LaSalle County Station, Units 1 and 2 - Request for Additional Information Related to Spent Fuel Storage Racks (TAC. Nos. ME6834 and ME6835),"
dated August 23, 2011 5.
Memorandum from A. T. Billoch Colon (U.S. NRC) to J. I. Zimmerman (U.S. NRC), "Forthcoming Public Meeting with Exelon Generation Company, LLC Regarding LaSalle County Station Units 1 and 2 Pre-Application for Spent Fuel Pool Neutron Absorbers Inserts," dated September 6, 2011 In Reference 1, Exelon Generation Company, LLC (EGC) requested an amendment to Facility Operating License Nos. NPF -11 and NPF-18 for LaSalle County Station (LSCS), Units 1 and 2, respectively. The proposed change revised Technical Specifications (TS) Section 4.3.1,
September 21, 2011 U.S. Nuclear Regulatory Commission Page 2 "Criticality," to address a non-conservative TS. Specifically, the proposed change addressed the BORAFLEX' degradation issue in the Unit 2 spent fuel storage racks by revising TS Section 4.3.1 to allow the use of NETCO-SNAP-IN rack inserts in Unit 2 spent fuel storage rack cells as a replacement for the neutron absorbing properties of the existing BORAFLEX' panels.
The NRC approved EGC's license amendment request in Reference 2. However, in Reference 2, the NRC noted that concerns regarding the long-term crediting of BORAFLEXTM in the LSCS spent fuel pools (SFPs) have yet to be resolved. As such, Reference 2 included license condition 2.C.(30) that established a three-tiered SFP BORAFLEXTM credit configuration that is valid until October 28, 2011. In Reference 3, EGC notified the NRC that the Unit 2 SFP had been reconfigured to comply with license condition 2.C.(30). Reference 2 also included license condition 2.C.(31) that established a more restricted-tiered configuration for crediting BORAFLEXTM until completion of the NETCO-SNAP-IN insert campaign. Compliance with license condition 2.C.(31) is required after October 28, 2011, until completion of the NETCO-SNAP-IN insert campaign.
In Reference 4, the NRC requested additional information that is needed to support the ongoing review of the LSCS Unit 2 SFP storage racks. The NRC clarified the request for additional information in a meeting between EGC and the NRC on August 25, 2011. During the meeting, EGC explained that a new criticality analysis would be necessary in order to fully respond to the NRC's request for additional information. EGC also discussed the timeframe for providing responses based on the fact that several of the RAIs require a new criticality analysis to be performed.
Based on the lengthy timeframe needed to respond, EGC proposed an alternative approach of addressing the NRC's concerns with crediting BORAFLEXTM for the interim configuration of the SFP. EGC's proposal involved accelerating the insert campaign and implementing controls to ensure that no fuel is stored in spent fuel storage rack cells without NETCO-SNAP-IN inserts.
Under EGC's proposal, the insert campaign would be accelerated such that no fuel would be stored in spent fuel storage rack cells without NETCO-SNAP-IN inserts in essentially the same amount of time that would be necessary to develop a new criticality analysis necessary to fully respond to the NRC's request for additional information as documented in Reference 4. During the meeting on August 25, 2011, the NRC agreed that EGC's proposal was reasonable; however, the NRC requested that the specific details be presented in a follow up meeting to be scheduled in the future.
The follow up meeting is currently scheduled for September 26, 2011 (i.e., Reference 5).
During the meeting, EGC plans to discuss the information below in order to provide more specific details regarding the alternative approach of addressing the NRC's concerns with crediting BORAFLEXTM for the interim configuration of the SFP.
Unit 2 license condition 2.C.(31) currently states:
After October 28, 2011, for the storage cells in the rack modules without NETCO-SNAP-IN inserts in the LSCS Unit 2 SFP, the following categories will apply:
Unrestricted, Restricted, and Unusable.
September 21, 2011 U.S. Nuclear Regulatory Commission Page 3 (a)
Unrestricted will be cells whose minimum panel B10 areal density is greater than or equal to 0.0200 g/cm2, Unrestricted cells may contain fuel assemblies up to the maximum reactivity identified in TS 4.3.1.1.d.
(b)
Restricted will be cells whose minimum panel B10 areal density is between 0.0200 g/cm2 and 0.0167 g/cm2. Restricted cells will only contain LSCS Units 1 and 2 Cycle 1 GE and GE14 fuel assemblies.
(c)
Unusable will be cells whose minimum panel B10 areal density is less than or equal to 0.0167 g/cm2. Unusable cells will be administratively controlled to remain empty of any fuel assembly.
The first element of EGC's proposal is to continue current insert installation and SFP reconfiguration activities to ensure that the criteria in Unit 2 license condition 2.C.(31) are met after October 28, 2011.
The second element of EGC's proposal is to accelerate the insert campaign. Unit 2 license condition 2.C.(32) currently states:
To ensure the ongoing Boraflex degradation will not exceed the spent fuel pool criticality limits, Exelon shall complete loading all accessible storage rack cells in the LSCS Unit 2 spent fuel pool with NETCO-SNAP-IN inserts no later than December 31, 2014.
EGC's proposal is to accelerate the insert campaign such that complete loading of all accessible storage rack cells in the LSCS Unit 2 SFP with NETCO-SNAP-IN inserts will be complete no later than December 31, 2012.
Finally, the third element of EGC's proposal is to ensure that no fuel is stored in spent fuel storage rack cells without NETCO-SNAP-IN inserts in the LSCS Unit 2 SFP after March 31, 2012. This timeframe in essentially the same amount of time that would be necessary to develop and submit a new criticality analysis necessary to fully respond to the NRC's request for additional information as documented in Reference 4. This element resolves concerns with crediting BORAFLEXTM in the LSCS Unit 2 SFP because the criticality analysis associated with the inserts, which was approved by the NRC in Reference 2, does not credit BORAFLEXTM.
The information above is being submitted to the NRC in lieu of specific responses to the information requested in Reference 4. EGC will discuss this information during the meeting on September 26, 2011, and follow up actions will be determined after the meeting.
September 21, 2011 U.S. Nuclear Regulatory Commission Page 4 There are no regulatory commitments contained in this letter. Should you have any questions concerning this letter, please contact Mr. Kenneth M. Nicely at (630) 657-2803.
Patrick R. Simpson Manager - Licensing cc:
NRC Regional Administrator, Region III NRC Senior Resident Inspector - LaSalle County Station Illinois Emergency Management Agency - Division of Nuclear Safety