ML032170639
| ML032170639 | |
| Person / Time | |
|---|---|
| Site: | Mcguire, Catawba, McGuire  |
| Issue date: | 07/29/2003 |
| From: | Mccollum W Duke Energy Corp |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML032170639 (5) | |
Text
Duke Duke Energy Corporation W Energy.
PO. Box 1006 Charlotte, NC 28201-1006 July 29, 2003 U. S. Nuclear Regulatory Commission Washington, D. C. 20555-0001 Attention: Document Control Desk
Subject:
Duke Energy Corporation McGuire Nuclear Station, Units 1 and 2 Docket Numbers 50-369 and 50-370 Catawba Nuclear Station, Units 1 and 2 Docket Numbers 50-413 and 50-414 Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model
Reference:
- 1) Letter, M. S. Tuckman (Duke Energy Corporation), to U. S. Nuclear Regulatory Commission,
SUBJECT:
"License Amendment Request, Implementation of Best-Estimate Large Break Loss of Coolant Accident Analysis Methodology," August 10, 2000.
10 CFR 50.46 (a)(3)(ii) requires the reporting of changes to or errors in ECCS evaluation models (EM) or in the application of such models that affect the temperature calculation. On July 11, 2003 Duke Energy Corporation received notification from Westinghouse Electric Company indicating a change in the limiting case for the Best-Estimate Large Break Loss of Coolant Accident (BELBLOCA) analysis in excess of 50'F.
The original BELBLOCA analysis considered a safety injection water temperature range of 70 -
100 F. This temperature range was based on the temperature of the refueling water storage tank (RWST) temperature. Safety injection flow at McGuire/Catawba is provided by three different pumps: a charging pump, a safety injection pump, and a residual heat removal (RHR) pump.
The injection flow from the RHR pumps passes through the RHR heat exchanger before entering the reactor coolant system. Thus, the water supplied by the RHR pump can be cooled prior to being injected into the RCS. McGuire system engineers observed that the component cooling water can be as low as 45 F during winter conditions. With component cooling water temperatures below the RWST temperature, the injection water temperature could be below the temperature range considered in the BELBLOCA analysis.
Previous McGuire/Catawba large break LOCA calculations have shown that colder injection temperatures can lead to an increase in the calculated peak cladding temperature (PCT). To evaluate lower safety injection water temperatures additional WCOBRAYTRAC calculations were performed. The revised WCOBRAITRAC results were used to assess a new injection temperature range 58 - 90 F. The impact of this revised temperature range was determined to AUUI
a U. S. Nuclear Regulatory Commission July 29, 2003 Page 2 have a PCT penalty of 59 F. The absolute values of the PCT change is greater than 50'F and therefore is considered to be a significant error/change per the definition in 10 CFR 50.46. It should be noted that the final PCT (2115 F) is still within the 10 CFR 50.46 acceptance criteria.
Summaries of the large break LOCA peak cladding temperatures for the McGuire and Catawba units are provided in Tables 1 and 2, which are attached to this letter. At Catawba, the component cooling water temperature is maintained warm enough such that the original safety injection temperature range remains valid. However upon a safety injection signal, the temperature controller valve would open and the component cooling water temperatures could approach those observed at McGuire. Therefore, the PCT penalty calculated for the McGuire conditions is conservatively applied to Catawba as well.
This evaluation was performed consistent with the method prescribed in Reference 1. The impact of this plant change was first evaluated on the composite model. There are no differences in plant configuration that would suggest that the composite model evaluation of safety injection temperature effects would be not be applicable to the McGuire/Catawba units. The reference transient is not impacted by this evaluation, and the only change from this assessment is that a new safety injection temperature range is specified.
10 CFR 50.46 (a)(3)(ii) also requires a proposed schedule for reanalysis for changes that are determined to be significant. The assessment of the PCT impact is based on plant-specific WCOBRA/TRAC calculations and, therefore, no further analysis is needed.
Please address any comments or questions regarding this matter to J. S. Warren at (704) 382-4986.
Very truly yours, R. McCollum, Senior Vice Presid Support
U. S. Nuclear Regulatory Commission July 29, 2003 Page 3 xc w/
Attachment:
L. A. Reyes, Regional Administrator U. S. Nuclear Regulatory Commission, Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30303 R. E. Martin (Addressee Only)
NRC Senior Project Manager (MNS and CNS)
U. S. Nuclear Regulatory Commission Mail Stop 0-8 H12 Washington, DC 20555-0001 J. B. Brady Senior Resident Inspector (MNS)
U. S. Nuclear Regulatory Commission McGuire Nuclear Site E. F. Guthrie Senior Resident Inspector (CNS)
U. S. Nuclear Regulatory Commission Catawba Nuclear Site
-1.
U. S. Nuclear Regulatory Commission July 29, 2003 Page 4 Table 1 Peak Cladding Temperature Summary - McGuire Units 1 & 2 LBLOCA Cladding Temp F)
Comments Evaluation model: WCOBRA/TRAC Analysis of record PCI' 2028 MNS/CNS Composite Model Prior errors (APCT)
- 1. Decay heat in Monte Carlo calculations 8
Reference A
- 2. MONTECF power uncertainty correction 20 Reference B Prior evaluation model changes (APCT)
- 1. None 0
Errors (APCT)
- 1. Safety Injection Temperature Range 59 Note (I)
Evaluation model changes (APCT)
- 1. None 0
Absolute value of errors/changes for this report (APCT) 0 Net change in PCI for this report 59 Final PCI' 2115
References:
A) Letter, M. S. Tuckman (DEC) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", May 3, 2001 B) Letter, M. S. Tuckman (DEC) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", April 3, 2002 Note:
- 1) An evaluation was performed to reduce the safety injection temperature range to 58 - 90 'F. The analysis supports a RWST temperature range of 70 - 100 'F and a component cooling water temperature range of 45 - 80 OF.
U. S. Nuclear Regulatory Commission July 29, 2003 Page 5 Table 2 Peak Cladding Temperature Summary - Catawba Units 1 & 2 LBLOCA Cladding Temp (0 F)
Comments Evaluation model: WCOBRAJTRAC Analysis of record PCT 2028 MNS/CNS Composite Model Prior errors (APCT)
- 1. Decay heat in Monte Carlo calculations 8
Reference A
- 2. MONTECF power uncertainty correction 20 Reference B Prior evaluation model changes (APCT)
- 1. None 0
Errors (APC)
- 1. Safety Injection Temperature Range 59 Note (1)
Evaluation model changes (APCT)
- 1. None 0
Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 59 Final PCT 2115
References:
A) Letter, G. R. Peterson (DEC) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", April 11, 2001 B) Letter, M. S. Tuckman (DEC) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model", April 3, 2002 Note:
- 1) An evaluation was performed to reduce the safety injection temperature range to 58 - 90 'F. The analysis supports a RWST temperature range of 70 - 100 'F and a component cooling water temperature range of 45 - 80 OF.