ML040220400
| ML040220400 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 02/24/2004 |
| From: | Mahesh Chawla NRC/NRR/DLPM/LPD3 |
| To: | Crane C Exelon Generation Co |
| Chawla M, NRR/.DLPM, 415-8371 | |
| References | |
| GL-96-006, TAC M96782, TAC M96783, TAC M96789, TAC M96790 | |
| Download: ML040220400 (6) | |
Text
February 24, 2004 Mr. Christopher M. Crane, President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
BYRON STATION, UNITS 1 AND 2, AND BRAIDWOOD STATION, UNITS 1 AND 2, GENERIC LETTER 96-06, ASSURANCE OF EQUIPMENT OPERABILITY AND CONTAINMENT INTEGRITY DURING DESIGN-BASIS ACCIDENT CONDITIONS (TAC NOS. M96789, M96790, M96782, AND M96783)
Dear Mr. Crane:
On September 30, 1996, the U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 96-06, "Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions, which included a request for licensees to evaluate cooling water systems that serve containment air coolers to assure that they are not vulnerable to water hammer and two-phase flow conditions, and to thermally-induced overpressurization.
In letters dated October 28, 1996, and January 28, 1997, Exelon Generation Company, LLC, the licensee (previously the Commonwealth Edison Company) submitted its 30-day and 120-day responses to GL 96-06. In a letter dated May 2, 1997, the licensee provided additional details of their approach to resolution of GL 96-06 concerns. On November 13, 1997, NRC issued supplement 1 to GL 96-06 to inform the licensees about ongoing efforts and new developments associated with GL 96-06 and to provide additional guidance for completing corrective actions. In response to questions that were asked by the NRC, the licensee provided additional information in letters dated June 30, August 14, August 27 and September 30, 1998; February 26 and October 27, 1999; November 6, 2000 and March 20, 2003.
The two requested actions in GL 96-06 were to address: 1) Water Hammer and Two-Phase Flow Conditions, and 2) Thermally-Induced Overpressurization. Based on our review of the information that you provided, we are satisfied with your resolution of these issues for the Byron and Braidwood Stations as discussed in the evaluations that follow.
(1) Water Hammer and Two-Phase Flow Conditions Subsequent to issuance of GL 96-06, the Electric Power Research Institute (EPRI) developed an analytical methodology for evaluating the GL 96-06 water hammer issue that was documented in EPRI Technical Reports 1003098 and 1006456 (previously known as EPRI Report TR-113594), and approved by the NRC in an evaluation dated April 3, 2002 (included as Appendix A to EPRI Technical Report 1003098). Section 3.3 of the staffs evaluation requested
C. Crane that licensees who chose to use the EPRI methodology provide additional information to confirm that the methodology was applicable for their specific application and that it was being applied properly, and to justify any proposed exceptions.
The licencee used the RELAP5 computer code to facilitate its application of the approved EPRI methodology and while the analysis appeared to be reasonable, this specific application of the RELAP5 computer code has not been reviewed and approved by the NRC. Therefore, in order to resolve concerns associated with use of the RELAP5 computer code, the licensee was asked to provide additional information in order to demonstrate that its analyses were in fact conservative. The licensee provided this additional information for the Braidwood and Byron units in a letter dated March 20, 2003.
Based on our review of the information that was provided, regarding Exelons application of EPRI methodology, we are satisfied with Exelons evaluation of the water hammer and two-phase flow issues. The licensee has provided sufficient confirmation that the EPRI methodology was properly applied for analyzing the GL 96-06 water hammer issue, and that plant-specific risk considerations are consistent with the EPRI risk perspective. With respect to two-phase flow, the licensee has determined that boiling will not take place in the service water piping downstream of the containment fan coolers after cooling water flow has been reestablished following event initiation, and, therefore, two-phase flow will not occur. The licensee concluded that no plant modifications or procedure changes were necessary based on its evaluation of the GL 96-06 water hammer and two-phase flow issues. While we are satisfied with the licensee's resolution of the GL 96-06 water hammer and two-phase flow issues, we have reached this conclusion without performing either a detailed review of the licensees water hammer and two-phase flow analyses or a review of the licensee's use and application of computer codes for performing these analyses.
(2) Thermally-Induced Overpressurization In its submittal of January 28, 1997, the licensee identified 13 penetrations as potentially vulnerable to a water solid volume that may be subjected to an increase in pressure due to heating of trapped fluid. In its submittal of May 2, 1997, the licensee identified three additional penetrations vulnerable to thermally-induced pressurization. In these submittals, the licensee determined that these penetrations were operable but that additional corrective actions would be necessary.
In its submittal of August 27, 1998, the licensee responded to a request for additional information regarding the long-term plans for resolving this issue for these penetrations. In its most recent submittal of October 27, 1999, the licensee provided the final resolution for all 16 penetrations. The licensee stated that for one of these penetrations, adequate overpressure protection was found to already exist via a by-pass line, and for eight of these penetrations, design changes will be implemented including either the installation of relief valves or the installation of by-pass spring-loaded check valves.
The licensee also stated that for three of these penetrations, procedural changes are being implemented to either drain the lines or assure that the isolation valves will be left open. For the remaining four penetrations, the licensee performed detailed piping analyses based on the criteria in Appendix F to the ASME Code. The results of the analyses demonstrate that the
C. Crane maximum thermally-induced pressures in these piping segments meet the Appendix F acceptance criteria for the Level D condition.
With respect to thermally-induced pressurization of piping, the staff finds the licensees evaluations to be reasonable and acceptable. The staff concludes that the licensees corrective actions and evaluations provide an acceptable resolution for the issue of thermally-induced pressurization of piping runs penetrating containment.
The NRC staff concludes that the licensee has adequately addressed all the actions requested in GL 96-06. This letter closes out the staffs actions on the generic letter and TAC Nos.
M96782, M96783, M96789, and M96790. If you have any questions, please contact me at 301-415-2863, or by e-mail through the internet at mlc@nrc.gov.
Sincerely,
/RA/
Mahesh Chawla, Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos.: STN 50-454, and STN 50-455, STN 50-456, and STN 50-457 cc: See next page
C. Crane maximum thermally-induced pressures in these piping segments meet the Appendix F acceptance criteria for the Level D condition.
With respect to thermally-induced pressurization of piping, the staff finds the licensees evaluations to be reasonable and acceptable. The staff concludes that the licensees corrective actions and evaluations provide an acceptable resolution for the issue of thermally-induced pressurization of piping runs penetrating containment.
The NRC staff concludes that the licensee has adequately addressed all the actions requested in GL 96-06. This letter closes out the staffs actions on the generic letter and TAC Nos.
M96782, M96783, M96789, and M96790. If you have any questions, please contact me at 301-415-2863, or by e-mail through the internet at mlc@nrc.gov.
Sincerely,
/RA/
Mahesh Chawla, Project Manager, Section 2 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos.: STN 50-454, and STN 50-455, STN 50-456, and STN 50-457 cc: See next page DISTRIBUTION:
PUBLIC PD3-2 r/f AMendiola MChawla GDick PCoates OGC ACRS BWetzel AStone, RIII KManoly JTatum GHammer DSolorio ADAMS ACCESSION NO.: ML040220400 *see previous concurrence OFFICE PM:LPD3-2 PM:LPD3-2 LA:LPD3-2 NAME MChawla GDick PCoates DATE 02/23/04 02/23/04 02/23/04 OFFICE BC:SPLB BC:EMEB
- SC:LPD3-2 NAME DSolorio*
KManoly DPickett for AMendiola DATE 02/09/04 02/12/04 02/24/04 OFFICIAL RECORD COPY
Byron/Braidwood Stations cc:
Ms. C. Sue Hauser, Project Manager Westinghouse Electric Corporation Energy Systems Business Unit Post Office Box 355 Pittsburgh, PA 15230 Joseph Gallo Gallo & Ross 1025 Connecticut Ave., NW, Suite 1014 Washington, DC 20036 Howard A. Learner Environmental Law and Policy Center of the Midwest 35 East Wacker Dr., Suite 1300 Chicago, IL 60601-2110 U.S. Nuclear Regulatory Commission Byron Resident Inspectors Office 4448 N. German Church Road Byron, IL 61010-9750 Regional Administrator, Region III U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, IL 60532-4351 Ms. Lorraine Creek RR 1, Box 182 Manteno, IL 60950 Chairman, Ogle County Board Post Office Box 357 Oregon, IL 61061 Mrs. Phillip B. Johnson 1907 Stratford Lane Rockford, IL 61107 George L. Edgar Morgan, Lewis and Bockius 1800 M Street, NW Washington, DC 20036-5869 Attorney General 500 S. Second Street Springfield, IL 62701 Illinois Emergency Management Agency Division of Disaster Assistance &
Preparedness 110 East Adams Street Springfield, IL 62701-1109 Byron Station Plant Manager Exelon Generation Company, LLC 4450 N. German Church Road Byron, IL 61010-9794 Site Vice President - Byron Exelon Generation Company, LLC 4450 N. German Church Road Byron, IL 61010-9794 U.S. Nuclear Regulatory Commission Braidwood Resident Inspectors Office 35100 S. Rt. 53, Suite 79 Braceville, IL 60407 Chairman Will County Board of Supervisors Will County Board Courthouse Joliet, IL 60434 Braidwood Station Plant Manager Exelon Generation Company, LLC 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619 Ms. Bridget Little Rorem Appleseed Coordinator 117 N. Linden Street Essex, IL 60935
Byron/Braidwood Stations Document Control Desk - Licensing Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Site Vice President - Braidwood Exelon Generation Company, LLC 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619 Senior Vice President - Nuclear Services Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Vice President of Operations - Mid-West Pressurized Water Reactors Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Director - Licensing and Regulatory Affairs Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Regulatory Assurance Manager - Braidwood Exelon Generation Company, LLC 35100 S. Rt. 53, Suite 84 Braceville, IL 60407-9619 Regulatory Assurance Manager - Byron Exelon Generation Company, LLC 4450 N. German Church Road Byron, IL 61010-9794 Associate General Counsel Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Vice President - Licensing and Regulatory Affairs Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555 Manager Licensing - Braidwood, Byron and LaSalle Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555