ML20247P315
| ML20247P315 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 05/22/1998 |
| From: | Olshan L NRC (Affiliation Not Assigned) |
| To: | Sumner H SOUTHERN NUCLEAR OPERATING CO. |
| References | |
| GL-94-02, GL-94-2, TAC-M99066, TAC-M99067, NUDOCS 9805270405 | |
| Download: ML20247P315 (3) | |
Text
I l
Mr. H. L. Sumner, Jr.
May 22,1998 l-Vice President - Nucle:r Hatch Project Southem Nuclear Operating Company, Inc.
Post Office Box 1295 Birmingham, Alabama 35201-1295
SUBJECT:
STABILITY OPTION lil AT EDWIN 1. HATCH NUCLEAR PLANT, UNITS 1 AND 2 (TAC NOS. M99066 and M99067)
Dear Mr. Sumner:
l Long-term stability solution Option lll provides an automatic means of detecting and suppressing reactor instabilities by examining local power range monitor (LPRM) signals for unstable characteristics. The LPRMs are grouped into what are referred to as oscillation power range monitors (OPRM) for analysis to eliminate the individual effect of one LPRM. The solution concept was described in NEDO-31960, which was reviewed and approved by the NRC staff in 1993. You committed to use Option 111 in your response to Generic Letter 94-02.
Your implementation plan called for a 6-month evaluation period during which the trip functions would be disabled.
During the evaluation period, you discovered that the settings for the period based algorithm I
(PBA) in Option ill were too sensitive and were causing the system to incorrectly signal unstable conditions. By letter dated September 12,1997, we granted you an extension to the startup of each unit from its next refueling outage. The extension was granted to give you the -
opportunity to fix the problem with the PBA. It was determined that by modifying the corner frequency and period tolerance the system would function as designed. Your October 21, 1997, letter supplied data to support your request for modifications of the OPRM settings to 3 Hertz and 50 milliseconds. These settings are generally less sensitive than the previous settings (2 Hertz and 100 niilliseconds), but the information contained.in the referenced letter confirms that they still perform well for the test cases used in the bench top validation.
Furthermore, we evaluated the overall Option lli installation, including the new settings, during our December 1997, inspection at Hatch and concluded that the installation was adequate.
Therefore, TAC Nos. M99066 and M99067 are considered to be closed.
Sincerely, ORIGINAL SIGNED BY:
Leonard N. Olshan, Senior Project Manager Project Directorate ll-2 k
Division of Reactor Projects - 1/11 D
00 21 Office of Nuclear Reactor Regulation P
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Docket Nos. 50-321 and 50-366
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Mr. H. L. Sumner, Jr.
Vice President - Nuclear Hatch Project i
Southem Nuclear Operating Company, Inc.
Past Office Box 1295 Birmingham, Alabama 35201-1295
SUBJECT:
S STABILITY OPTION lli AT EDWIN 1. HATCH NUCLEAR Pl. ANT, UNITS 1 AND 2 (TAC NOS. M99066 and M99067)
Dear Mr. Sumner:
Long-term stability solution Option lli provides an automatic means of detecting and suppressing reactor instabilities by examining local power range monitor (LPRM) signals for unstable characteristics. The LPRMs are grouped into what are referred to as oscillation power range monitors (OPRM) for analysis to eliminate the individual effect of one LPRM. The solution concept was described in NEDO-31960, which was reviewed and approved by the NRC staff in 1993. You committed to use Option 111 in your response to Generic Letter 94-02.
Your iraplementation plan called for a 6-month evaluation period during which the trip functions would be disabled.
l During the evaluation period, you discovered that the settings for the period based algorithm (PBA) in Option 111 were too sensitive and were causing the system to incorrectly signal I
unstable conditions. By letter dated September 12,1997, we granted you an extension to the startup of each unit from its next refueling outage. The extension was granted to give you the opportunity to fix the problem with the PBA. It was determined that by modifying the comer frequency and period tolerance the system would function as designed. Your October 21, 1997, letter supplied data to support your request for modifications of the OPRM settings to 3 Hertz and 50 milliseconds. These settings are generally less sensitive than the previous settings (2 Hertz and 100 milliseconds), but the information contained in the referenced letter confirms that they still perform well for the test cases used in the bench top validation.
Furthermore, we evaluated the overall Option ill installation, including the new settings, during l
l our December 1997, inspection at Hatch and concluded that the installation was adequate.
l Therefore, TAC Nos. M99066 and M99067 are considered to be closed.
i l
Sincerely, l
1 Leonard N. Olshan, Senior Project Manager Project Directorate ll-2 Division of Reactor Projects - 1/II Office of Nuclear Reactor Regulation l
Docket Nos. 50-321 and 50-366 l
l cc: See next page
l
[
Edwin 1. Hatch Nuclear Plant l
cc:
Charles A. Patrizia, Esquire Mr. Emest L. Blake, Jr.
Paul, Hastings, Janofsky & Walker Shaw, Pittman, Potts
'10th Floor I
I and Trowbridge 1299 Pennsylvania Avenue I
2300 N Street, NW.
Washington, DC 20004-9500 Washington, DC 20037 1
Chairman Mr. D. M. Crowe Appling County Commissioners l
Manager, Licensing County Courthouse Southem Nuclear Operating Baxley, Georgia 31513 Company, Inc.
I P. O. Box 1295 Mr. J. D. Woodard Birmingham, Alabama 35201-1295 Executive Vice President Southem Nuclear Operating Resident inspector Company, Inc.
Plant Hatch P. O. Box 1295 11030 Hatch Parkway N.
Birmingham, Alabama 35201-1295 Baxley, Georgia 31531 Mr. P. W. Wells
]
Regional Administrator, Region ll General Manager, Edwin 1. Hatch U.S. Nuclear Regulatory Commission Nuclear Plant Atlanta Federal Center Southem Nuclear Operating 61 Forsyth Street, SW, Suite 23T85 Company, Inc.
Atlanta, Georgia 30303 U.S. Highway 1 North P. O. Box 2010 Mr. Charles H. Badger Baxley, Georgia 31515 Office of Planning and Budget Room 610 Mr. R. D. Barker 270 Washington Street, SW.
Program Manager Atlanta, Georgia 30334 Fossil & Nuclear Operations Oglethorpe Power Corporation Harold Reheis, Director 2100 East Exchange Place Department of Natural Resources P. O. Box 1349 205 Butler Street, SE., Suite 1252 Tucker, Georgia 30085-1349 Atlanta, Georgia 30334 Steven M. Jackson Senior Engineer - Power Supply Municipal Electric Authority of Georgia 1470 Riveredge Parkway, NW Atlanta, Georgia 30328-4684 l
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