ML030730762
| ML030730762 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 03/21/2003 |
| From: | John Lamb NRC/NRR/DLPM/LPD3 |
| To: | Nazar M Nuclear Management Co |
| References | |
| GL-96-006, TAC M96854, TAC M96855 | |
| Download: ML030730762 (5) | |
Text
March 21, 2003 Mr. Mano Nazar Site Vice President Prairie Island Nuclear Generating Plant Nuclear Management Company, LLC 1717 Wakonade Drive East Welch, MN 55089
SUBJECT:
PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2 - FINAL CLOSEOUT OF RESPONSES TO GENERIC LETTER 96-06 (TAC NOS. M96854 AND M96855)
Dear Mr. Nazar:
The U.S. Nuclear Regulatory Commission (NRC) staff issued Generic Letter (GL) 96-06, Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions, on September 30, 1996. In GL 96-06, the NRC staff requested licensees to determine for postulated accident conditions, if (1) containment air cooler cooling water systems are susceptible to either waterhammer or two-phase flow conditions, and (2) piping systems that penetrate containment are susceptible to thermal expansion of fluid so that overpressurization of piping could occur.
The Nuclear Management Company, LLC (NMC), the licensee, previously the Northern States Power Company, provided its assessment for the Prairie Island Nuclear Generating Plant, Units 1 and 2, in a letter dated January 28, 1997, and additional information was provided in letters dated September 15, 1997, May 15, 1998, January 8, 1999, September 30, 2002, and February 4, 2003.
This letter addresses the final closeout of GL 96-06 and is divided into two parts. The first part is the issue of waterhammer and two-phase flow. The second part is the thermal overpressurization issue.
In reference to the waterhammer and two-phase flow issue, it is the NRC staffs understanding that you adhered to the analytical methodology that was established by the Electric Power Research Institute (EPRI) for evaluating the GL 96-06 waterhammer issue. This EPRI methodology is documented in EPRI Technical Reports 1003098 and 1006456 (previously known as EPRI Report TR-113594), and found acceptable by the NRC in an evaluation dated April 3, 2002. Your September 30, 2002, response provided the information required by Section 3.3 of the NRC evaluation, and we understand that the Prairie Island Nuclear Generating Plant, Units 1 and 2, are not vulnerable to the waterhammer and two phase flow concerns discussed in GL 96-06. With respect to the two phase flow issue, it is the NRC staffs understanding that a number of modifications (some of which were initiated prior to issuance of GL 96-06) have been made to the Cooling Water system focused primarily on reducing or eliminating potential flow diversion paths, thereby enhancing system response during an accident. The NRC staff is satisfied with your response and consider the waterhammer and two-phase flow elements of GL 96-06 to be closed.
M. Nazar In reference to the thermal overpressurization issue, you summarized your review of fluid systems that are susceptible to overpressurization due to thermal expansion of internal fluid in the submittal dated January 28, 1997. You concluded that all except certain pipe segments associated with the reactor coolant pump seal water (RCPSW) return line, the sample lines, and the safety injection (SI) test line were dispositioned based on high operating temperature of the internal fluid, or the presence of certain pressure relief devices such as thermal relief valves, diaphragm valves, expansion bellows, check valves, and containment venting. You performed detailed evaluation of these affected pipe segments associated with the RCPSW return line, the sample lines, and the SI test line, and determined that their calculated internal pressures did not exceed the design basis maximum allowable pressure for these piping.
However, in your submittal dated January 8, 1999, you indicated that a more detailed analysis was performed for the SI test line, and the newly calculated internal pressure exceeded the maximum allowable values. As a result, you proposed to implement corrective actions to alleviate the potential overpressure problem for the SI test line by the end of each units next refueling outage, which occurred in April 1999, for Unit 1, and May 2000, for Unit 2. The NRC staff finds the corrective action acceptable.
Installation of a check valve, a relief valve, a diaphragm valve, an expansion bellow or applicable pressure relief devices, is an acceptable means for relieving pressure of a solid water volume. The NRC staff also finds that verifying the calculated internal pressures to be within the Code allowable pressure is an acceptable means to demonstrate the operability of affected piping segments. Therefore, the NRC staff concludes that your corrective actions, proposed plant modifications, and verifying the calculated internal pressures to be within the Code allowable provide an acceptable resolution for the issue of thermally-induced pressurization of piping runs penetrating the containment, and the closed piping segments inside the containment. The NRC staff is satisfied with your response and consider the thermally-induced pressurization element of GL 96-06 to be closed.
Please be advised that the NRC staff has not performed a detailed review of your waterhammer analysis, thermally-induced pressurization analysis, or the associated modifications that were made. They are subject to future NRC audit or inspection activity if any.
This completes the NRC staffs efforts regarding GL 96-06 for Prairie Island Nuclear Generating Plant, Units 1 and 2, under TAC Nos. M96854 and M96855.
If you have any questions regarding this matter, please contact me at (301) 415-1446.
Sincerely,
/RA/
John G. Lamb, Project Manager, Section 1 Project Directorate III Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-282 and 50-306 cc: See next page
- Provided input by memo OFFICE PDIII-1/PM PDIII-1/LA SPLB/SC*
EMEB/SC*
PDIII-1/SC NAME JLamb THarris for RBouling SWeerakkody KManoly LRaghavan DATE 03/21/03 03/21/03 02/24/03 06/30/00 03/21/03
Prairie Island Nuclear Generating Plant, Units 1 and 2 cc:
J. E. Silberg, Esquire Shaw, Pittman, Potts and Trowbridge 2300 N Street, N. W.
Washington, DC 20037 Site Licensing Manager Prairie Island Nuclear Generating Plant Nuclear Management Company, LLC 1717 Wakonade Drive East Welch, MN 55089 Adonis A. Neblett Assistant Attorney General Office of the Attorney General 455 Minnesota Street Suite 900 St. Paul, MN 55101-2127 U.S. Nuclear Regulatory Commission Resident Inspectors Office 1719 Wakonade Drive East Welch, MN 55089-9642 Regional Administrator, Region III U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, IL 60532-4351 Administrator Goodhue County Courthouse Box 408 Red Wing, MN 55066-0408 Commissioner Minnesota Department of Commerce 121 Seventh Place East Suite 200 St. Paul, MN 55101-2145 Tribal Council Prairie Island Indian Community ATTN: Environmental Department 5636 Sturgeon Lake Road Welch, MN 55089 Mr. Roy A. Anderson Executive Vice President and Chief Nuclear Officer Nuclear Management Company, LLC 700 First Street Hudson, WI 54016 Nuclear Asset Manager Xcel Energy, Inc.
414 Nicollet Mall Minneapolis, MN 55401 March 2002