ML003689045

Request for Assistance from NEI on Callaway Event

ML003689045
Person / Time
Site:	Callaway
Issue date:	03/02/2000
From:	Collins S Office of Nuclear Reactor Regulation
To:	Ralph Beedle Nuclear Energy Institute
Lazevnick J
References
99-005-00
Download: ML003689045 (18)

Text

March 2, 2000 Mr. Ralph Beedle Senior Vice President and Chief Nuclear Officer Nuclear Energy Institute 1776 I Street, N.W., Suite 400 Washington, D.C. 20006-3708

Dear Mr. Beedle:

A U.S. nuclear power plant (Callaway) reported an August 12, 1999 occurrence that, although not safety significant due to the actual plant conditions at the time, highlighted potential vulnerabilities of a generic nature that we would like your assistance in addressing. (See enclosed Licensee Event Report.)

The licensee for Callaway reported that with the plant in hot standby following a plant trip, the plant switchyard voltage was observed to decrease below the minimum operability limit established in the station procedures. This low voltage was attributed to the service territory loading that was near peak levels and to the magnitude of power being transported across the grid that had not been previously observed and was far in excess of typical levels. The licensee stated that the deregulated wholesale power market contributes to conditions in which higher grid power flows are likely to occur.

The licensee indicated that two days earlier, before the plant trip, similar grid loading conditions were present, but the low switchyard voltages were not observed at that time since Callaway generation was locally supporting grid voltage. As a result, the true capability of the offsite source could not be verified through direct readings when the unit was in operation.

The low switchyard voltages observed at Callaway did not result in insufficient safety bus voltages due to the electrical bus loading conditions at the time. However, had a larger complement of safety loads been required (such as those credited for mitigating a loss-of-coolant accident), safety bus voltages from the offsite power system may have been less than adequate to power those loads. This would result in actuation of the safety bus degraded voltage protection, separation from offsite power, and restarting of the safety loads onto the onsite diesel generators.

Other licensees have also identified situations in which a plant could be operating in a region that would result in insufficient offsite system voltages to safety equipment following a plant trip associated with a design basis event. The post-trip voltages cannot be directly monitored before the event because they are the result of the plant trip and various automatic switching actions

R. Beedle that take place at the time of the event. These switching actions include the starting of safety loads responding to the event, the transfer of nonsafety loads to the same source (transformer) that is feeding the safety loads, and the separation of the plant generator from the switchyard when it is providing voltage support to the yard. Because the post-trip voltages cannot be read directly before a plant trip, they must be derived from the plant and grid conditions that exist during operation of the plant.

In this regard, NRC Information Notice 95-37, September 7, 1995, addressed the potential that a failure to periodically update a plants voltage analysis as the result of changing offsite grid or plant conditions could result in unintentional operation outside regulatory requirements. NRC Information Notice 98-07, February 27, 1998, addressed a potential concern relating to electric power industry deregulation that could adversely affect the reliability of the offsite power sources. It reiterated the need to ensure that the design bases with respect to the reliability and stability of the offsite power sources do not degrade during the life of the nuclear facility. We are also currently in the process of issuing an Information Notice and Inspection Report on the issues surrounding the Callaway event.

Our staff found from its work (ORNL/NRC/LTR/98-12, August 1998) on utility industry deregulation that there is significant variation between control areas, and utilities within control areas, regarding the amount of attention paid to this subject. The safety consequences that would result if an event, albeit unlikely, occurred during a period of degraded grid voltage are difficult to assess because most licensees have not analyzed all of their systems for the double-starting and degraded-voltage operation they might undergo in such a scenario. Maintaining adequate offsite power is a requirement of General Design Criterion (GDC) 17 and plant technical specifications.

We would like to better understand the risk implications of electrical system designs under degraded voltage conditions, including information on plant-specific risks of degraded-voltage and double-starting scenarios. Because of the variable nature of this scenarios initiating frequency and effect on safety equipment, a wide range of risk across the population of nuclear plants appears possible. We have found from our work (NUREG/CR-6538, July 1997) on this subject that these scenarios have not been evaluated in the majority of plant-specific probabilistic risk assessments.

We believe that our licensees are in the best position to assess this situation, understand the risks, and decide what, if any, actions need to be taken to assure continued compliance with GDC 17. Therefore, we propose that this subject be addressed as a voluntary industry initiative. Your help on these matters would be appreciated. We would like to schedule a public meeting

R. Beedle in the near future to discuss this issue and an approach for interaction with the industry. Please contact José A. Calvo of my staff at (301) 415-2774.

Sincerely,

(/RA by S. J. Collins)

Samuel J. Collins, Director Office of Nuclear Reactor Regulation

Enclosure:

Licensee Event Report dated September 13, 1999 cc w/enc: See attached lists

R. Beedle in the near future to discuss this issue and an approach for interaction with the industry. Please contact José A. Calvo of my staff at (301) 415-2774.

Sincerely,

(/RA by S. J. Collins)

Samuel J. Collins, Director Office of Nuclear Reactor Regulation

Enclosure:

Licensee Event Report dated September 13, 1999 cc w/enc: See attached lists DISTRIBUTION:

File Center/ADAMS EEIB R/F Callaway S/F ERossi JRosenthal HMiller, RI LReyes, RII JDyer, RIII EMerschoff, RIV DISK/DOCUMENT NAME: C:\Letter to NEI.wpd See previous concurrences To receive copy, indicate: C = Copy w/o attachment/enclosure; A = Copy with attachment/enclosure; N = None OFC EEIB A Tech Ed N SC:EEIB A C:EEIB A DD:DE A D:DE A ADPT:NRR A D:NRR NAME JJLazevnick:jc BCalure DFThatcher JACalvo RHWessman JRStrosnider BWSheron SJCollins DATE 12/01/99 12/01/99 12/02/99 12/02/99 12/06/99 01/20/00 02/14/00 03/02/00 OFFICIAL RECORD COPY

R. Beedle Nuclear Energy Institute cc:

Mr. Joe F. Colvin President and Chief Executive Officer Nuclear Energy Institute Suite 400 1776 I Street, NW Washington, DC 20006-3708 Ms. Lynnette Hendricks, Director Plant Support Nuclear Energy Institute Suite 400 1776 I Street, NW Washington, DC 20006-3708 Mr. Alex Marion, Director Programs Nuclear Energy Institute Suite 400 1776 I Street, NW Washington, DC 20006-3708 Mr. David Modeen, Director Engineering Nuclear Energy Institute Suite 400 1776 I Street, NW Washington, DC 20006-3708 Mr. Anthony Pietrangelo, Director Licensing Nuclear Energy Institute Suite 400 1776 I Street, NW Washington, DC 20006-3708 Mr. Jim Davis, Director Operations Nuclear Energy Institute Suite 400 1776 I Street, NW Washington, DC 20006-3708 Boiling Water Reactor Owners Group

R. Beedle cc:

Mr. W. Glenn Warren Mr. George T. Jones BWR Owners Group Chairman PP& L, Inc.

Southern Nuclear Company MC GENA6-1 42 Inverness Parkway Two North Ninth Street PO Box 1295 Allentown, PA 18101 Birmingham, AL 35201 Mr. John Kelly Mr. James M. Kenny New York Power Authority BWR Owners Group Vice Chairman 14th Floor Mail Stop 14K PP&L, Inc. Centroplex Building Mail Code GENA6-1 123 Main Street Allentown, PA 18101-1179 White Plains, NY 10601 Mr. Thomas J. Rausch Mr. Thomas G. Hurst RRG Chairman GE Nuclear Energy Commonwealth Edison Company M/C 182 Nuclear Fuel Services 175 Curtner Avenue 1400 Opus Place, 4th Floor San Jose, CA 95125 Downers Grove, IL 60515-5701 Mr. Thomas A. Green Mr. Drew B. Fetters GE Nuclear Energy PECO Energy M/C 182 Nuclear Group Headquarters 175 Curtner Avenue MC 61A-3 San Jose, CA 95125 965 Chesterbrook Blvd.

Wayne, PA 19087-5691 Mr. H. Lewis Sumner Southern Nuclear Company 40 Inverness Parkway PO Box 1295 Birmingham, GA 35201 Mr. Carl D. Terry Vice President, Nuclear Engineering Niagara Mohawk Power Corporation Nine Mile Point - Station OPS Bldg/2nd Floor PO Box 63 Lycoming, NY 13093 CE Owners Group cc:

R. Beedle Mr. Gordon C. Bischoff, Project Director CE Owners Group ABB Combustion Engineering Nuclear Power M.S. 9615-1932 2000 Day Hill Road Post Office Box 500 Windsor, CT 06095 Mr. Ralph Phelps, Chairman CE Owners Group Omaha Public Power District P.O. Box 399 Ft. Calhoun, NE 68023-0399 Mr. Ian C. Rickard, Director Nuclear Licensing ABB Combustion Engineering Nuclear Power 2000 Day Hill Road Post Office Box 500 Windsor, CT 06095 Mr. Charles B. Brinkman, Manager Washington Operations ABB Combustion Engineering Nuclear Power 12300 Twinbrook Parkway, Suite 330 Rockville, MD 20852

R. Beedle Westinghouse Owners Group cc:

Mr. H. A. Sepp, Manager Regulatory and Licensing Engineering Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, PA 15230-0355 Mr. Andrew Drake, Project Manager Westinghouse Owners Group Westinghouse Electric Corporation Mail Stop ECE 5-16 P.O. Box 355 Pittsburgh, PA 15230-0355 Mr. Jack Bastin, Director Regulatory Affairs Westinghouse Electric Corporation 11921 Rockville Pike Suite 107 Rockville, MD 20852

R. Beedle B&W Owners Group cc:

Randy Hutchinson, Chairman B&WOG Executive Committee Vice President Operations Arkansas Nuclear One Entergy Operations, Inc.

1448 S.R. 333 Russellville, AK 72801-0967 Mr. W. W. Foster, Chairman B&WOG Steering Committee Director of Safety Assurance Duke Power Company Oconee Nuclear Station P.O. Box 1439 Seneca, SC 29679 Mr. J. J. Kelly, Manager B&W Owners Group Services Framatome Technologies, Inc.

P.O. Box 10935 Lynchburg, VA 24506-0935 Mr. F. McPhatter, Manager Framatome Cogema Fuels 3315 Old Forest Road P.O. Box 10935 Lynchburg, VA 24506-0935 Mr. R. Schomaker, Manager Framatome Cogema Fuels 3315 Old Forest Road P.O. Box 10935 Lynchburg, VA 24506-0935 Mr. Michael Schoppman Licensing Manager Framatome Technologies, Inc.

1700 Rockville Pike, Suite 525 Rockville, MD 20852-1631

R. Beedle Electric Power Research Institute cc:

Mr. Gary L. Vine Senior Washington Representative Electric Power Research Institute 2000 L Street, N.W., Suite 805 Washington, DC 20036 Mr. James F. Lang Electric Power Research Institute Post Office Box 217097 1300 W.T. Harris Boulevard Charlotte, NC 28262 Mr. Bindi Chexal Electric Power Research Institute Post Office Box 10412 Palo Alto, CA 94303 Mr. Raymond C. Torok Project Manager, Nuclear Power Group Electric Power Research Institute Post Office Box 10412 Palo Alto, CA 94303

R. Beedle BWR Vessel & Internals Project Group cc:

Bill Eaton, Executive Chair Carl Larsen, Technical Chairman BWRVIP Inspection Committee BWRVIP Inspection Task Entergy Operations, Inc. P.O. Box 157 PO Box 756, Waterloo Rd Vernon, VT 05354 Port Gibson, MS 39150-0756 John Wilson, Technical Chairman Harry P. Salmon, Executive Chairman BWRVIP Mitigation Task BWRVIP Integration Task Clinton Power Station, M/C T-31C New York Power Authority P.O. Box 678 123 Main St., M/S 11 D Clinton, IL 61727 White Plains, NY 10601-3104 Vaughn Wagoner, Technical Chairman James P. Pelletier, BWRVIP Liaison BWRVIP Integration Task to EPRI Nuclear Power Council Carolina Power & Light Company Nebraska Public Power District One Hannover Square 9C1 1200 Prospect Avenue P.O. Box 1551 PO Box 98 Raleigh, NC 27612 Brownville, NE 68321-0098 Bruce McLeod, Technical Chairman Robert Carter, EPRI BWRVIP Assessment BWRVIP Repair Task Manager Southern Nuclear Operating Co.

Greg Selby, EPRI BWRVIP Inspection Post Office Box 1295 Manager 40 Inverness Center Parkway EPRI NDE Center Birmingham, AL 35201 P. O. Box 217097 1300 W. T. Harris Blvd. Tom Mulford, EPRI BWRVIP Integration Charlotte, NC 28221 Manager Raj Pathania, EPRI BWRVIP Mitigation Joe Hagan, BWRVIP Vice Chairman Manager PEPCO Energy Co. Ken Wolfe, EPRI BWRVIP Repair Manager MC 62C-3 Electric Power Research Institute 965 Chesterbrook Blvd P. O. Box 10412 Wayne, PA 19807-5691 3412 Hillview Ave.

Palo Alto, CA 94303 Steve Lewis, Technical Chairman BWRVIP Assessment Task Mr. Ray Shadis, Staff Entergy New England Coalition on Nuclear Pollution P. O. Box 756 P. O. Box 76 Waterloo Road Edgecomb, Maine 04556 Port Gibson, MS 39150 BWR Vessel & Internals Project Group (cont.)

R. Beedle cc:

Mr. David Kraft Nuclear Energy Information Services P. O. Box 1637 Evanston, IL 60204