ML15112A598
| ML15112A598 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/13/1998 |
| From: | Labarge D NRC (Affiliation Not Assigned) |
| To: | Mccollum W DUKE POWER CO. |
| References | |
| TAC-M99297, TAC-M99298, TAC-M99299, NUDOCS 9804140340 | |
| Download: ML15112A598 (5) | |
Text
Mr. W. R. McCollum April 13, 1998 Vice President, Oconee SO Duke Energy Corporation P. 0. Box 1439 Seneca, SC 29679
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION - PROPOSED MAIN FEEDWATER ISOLATION TECHNICAL SPECIFICATION (TS) CHANGE OCONEE UNITS 1, 2, AND 3 (TAC NOS. M99297, M99298, AND M99299)
Dear Mr. McCollum:
By letter dated March 3, 1998, Duke Energy Corporation responded to the staff's February 9, 1998, request for additional information regarding the single failure capability of the main feedwater (MFW) isolation capability following a main steamline break (MSLB) inside containment. The response indicated that the MFW isolation design cannot meet all potential single failures for the worst case MSLB without exceeding containment design pressure.
Bulletin 80-04 required licensees to make modifications as necessary to prevent containment overpressure under these circumstances. Modifications to address this issue have been made at Oconee Nuclear Station, Units 1, 2, and 3, but the final design is slightly less conservative than other plants responding to Bulletin 80-04. Also, since the design cannot withstand all postulated single failures, it may not adequately address the Bulletin 80-04 concerns.
In order to complete our evaluation of the proposed TS change and to fully address the Bulletin 80-04 concerns, the staff has determined that additional information and analysis are needed to complete its review, as explained in the enclosure.
Sincerely, ORIGINAL SIGNED BY:
David E. LaBarge, Senior Project Manager Project Directorate 11-2 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, and 50-287
Enclosure:
As stated cc w/encl: See next page Distribution:
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REG UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 April 13, 1998 Mr. W. R. McCollum Vice President, Oconee Site Duke Energy Corporation P. 0. Box 1439 Seneca, SC 29679
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION - PROPOSED MAIN FEEDWATER ISOLATION TECHNICAL SPECIFICATION (TS) CHANGE OCONEE UNITS 1, 2, AND 3 (TAC NOS. M99297, M99298, AND M99299-)
Dear Mr. McCollum:
By letter dated March 3, 1998, Duke Energy Corporation responded to the staffs February 9, 1998, request for additional information regarding the single failure capability of the main feedwater (MFW) isolation capability following a main steamline break (MSLB) inside containment. The response indicated that the MFW isolation design cannot meet all potential single failures for the worst case MSLB without exceeding containment design pressure.
Bulletin 80-04 required licensees to make modifications as necessary to prevent containment overpressure under these circumstances. Modifications to address this issue have been made at Oconee Nuclear Station, Units 1, 2, and 3, but the final design is slightly less conservative than other plants responding to Bulletin 80-04. Also, since the design cannot withstand all postulated single failures, it may not adequately address the Bulletin 80-04 concerns.
In order to complete our evaluation of the proposed TS change and to fully address the Bulletin 80-04 concerns, the staff has determined that additional information and analysis are needed to complete its review, as explained in the enclosure.
Sincerely, David E. LaBarge, Senior Project Manager Project Directorate 11-2 Division of Reactor Projects - III Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, and 50-287
Enclosure:
As stated cc w/encl: See next page
Oconee Nuclear Station cc:
Mr. Paul R. Newton Mr. J. E. Burchfield Legal Department (PBO5E)
Compliance Manager Duke Energy Corporation Duke Energy Corporation 422 South Church Street Oconee Nuclear Site Charlotte, North Carolina 28242 P. 0. Box 1439 Seneca, South Carolina 29679 J. Michael McGarry, III, Esquire Winston and Strawn Ms. Karen E. Long 1400 L Street, NW.
Assistant Attorney General Washington, DC 20005 North Carolina Department of Justice Mr. Robert B. Borsum P. 0. Box 629 Framatome Technologies Raleigh, North Carolina 27602 Suite 525 1700 Rockville Pike L. A. Keller Rockville, Maryland 20852-1631 Manager - Nuclear Regulatory Licensing Manager, LIS Duke Energy Corporation NUS Corporation 526 South Church Street 2650 McCormick Drive, 3rd Floor Charlotte, North Carolina 28242-0001 Clearwater, Florida 34619-1035 Mr. Richard M. Fry, Director Senior Resident Inspector Division of Radiation Protection U. S. Nuclear Regulatory North Carolina Department of Commission Environment, Health, and 7812B Rochester Highway Natural Resources Seneca, South Carolina 29672 3825 Barrett Drive Raleigh, North Carolina 27609-7721 Regional Administrator, Region II U. S. Nuclear Regulatory Commission Atlanta Federal Center 61 Forsyth Street, S.W., Suite 23T85 Atlanta, Georgia 30303 Max Batavia, Chief Bureau of Radiological Health South Carolina Department of Health and Environmental Control 2600 Bull Street Columbia, South Carolina 29201 County Supervisor of Oconee County Walhalla, South Carolina 29621
REQUEST FOR ADDITIONAL INFORMATION MAIN STEAMLINE BREAK AMENDMENT OCONEE, UNITS 1. 2. AND 3 In the March 3, 1998, letter regarding Technical Specification (TS) Change No. 95-03, Duke Energy Corporation (DEC) provided responses to our February 9, 1998, request for additional information regarding the single failure capability of the main steamline break (MSLB) main feedwater (MFW) isolation capability at the Oconee Nuclear Station, Units 1, 2, and 3. In the response, DEC provided information to support the position that the MFW isolation capability is adequate even though it cannot withstand all possible single active failures. The failure of concern is a failure of the MFW control valve to close allowing continued feedwater addition from the condensate pumps (MFW pumps assumed tripped). Since the critical aspects have been analyzed and found acceptable with continued MFW addition, the only analysis of concern is the containment analysis.
DEC's response also identified that credit is not being taken for the MFW block valves because (1) the stroke times are insufficient to assure containment protection, (2) the valves are not designed to stroke at the high differential pressures associated with the most severe MSLBs, and (3) the valve motor operators do not have safety-related power supplies.
While the staff agrees with DEC's assertion that this is a low probability event (MSLB plus failure of MFW control valve to close), the stated position and design are less conservative than any other plant responding to Bulletin 80-04. We, therefore, request further justification for DEC's position so the staff can conclude that the less conservative design is acceptable and to develop a safety evaluation regarding your proposed TS change. To complete our review, the following additional information is needed:
- 1. Provide the results of a containment analysis (as requested by Bulletin 80-04) that reflects the actual design of the MFW isolation capability at Oconee. The analysis should assume that feedwater continues to be added to the faulted steam generator (via the condensate pumps) for 10 minutes (assumed for operator action to secure flow) or for the time it takes to isolate MFW flow via the MFW block valves if they can close under the differential pressure associated with the condensate pumps. The analysis can take credit for all containment cooling features, since no other single failures need be assumed. The analysis should also assume that offsite power is available since the condensate pumps would not be running for a loss of offsite power.
- 2. Identify the stroke time of the MFW block valves that would exist with the worst case differential pressures following an MSLB with operation of the condensate pumps. If the stroke time is less than 10 minutes, provide further justification for not including these valves in the proposed TS.
- 3. In its response, DEC stated that there is a high probability that the containment would not fail even if the design pressure was exceeded. Use the results of the analysis from Item 1, above, to support the conclusion that the containment is not likely to fail following the worst case MSLB inside containment and a failure of the MFW control valve to close.
Enclosure
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