ML031420812
| ML031420812 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/19/2003 |
| From: | Mccollum W Duke Energy Corp |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML031420812 (7) | |
Text
Duke c #Energy.
May 19, 2003 U. S. Nuclear Regulatory Commission Washington, D. C. 20555-001 Attention:
Document Control Desk
Subject:
Duke Energy Corporation Oconee Nuclear Station, Units 1, 2, and 3 Docket Numbers 50-269, 50-270, and 50-287 Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model
References:
- 1) Letter, L. W. Barnett (USNRC) to J. F.
Malloy (FANP), "Safety Evaluation of Framatome Technologies Topical Report BAW-10164-P, Revision 4 -
RELAP5/MOD2-B&W, An Advanced Computer Program for Light Water Reactor LOCA and Non-LOCA Transient Analyses," April 9, 2002.
- 2) Letter, M. S. Tuckman (DEC) to USNRC, "Report Pursuant to 10 CFR 50.46, Error Related to Application of the LBLOCA Evaluation Model",
May 31, 2002.
10 CFR 50.46 (a)(3)(ii) requires the reporting of changes to or errors in ECCS evaluation models (EM). This report covers the time period from January 1, 2002 to December 31, 2002.
During this time period, there were three changes made to the evaluation model or in the application of the model.
Only one change had an impact on the calculated peak cladding temperatures (PCTs) and is classified as an insignificant change (APCT < 50°F).
This change is related to the implementation of the void-dependent cross-flow model used in the Small Break LOCA (SBLOCA) analysis which was approved by the NRC in Reference 1.
Duke Energy Corporation 526 South Church Street P.O. Box 1006 Charlotte, NC 28201-1006
U. S. Nuclear Regulatory Commission May 19, 2003 Page 2 Included in this report are three summary tables.
Table 1 provides the changes/errors for which a PCT impact has been assessed.
Table 2 presents changes/errors for which no PCT impact has been assessed.
Table 3 provides a summary of the peak cladding temperatures for all three units.
Please address any comments or questions regarding this matter to J. S. Warren at (704) 382-4986.
Very truly yours, W. R. McCollum, Senior Vice President, Nuclear Support Attachments xc:
L. A. Reyes U. S. Nuclear Regulatory Commission Regional Administrator, Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30303-8931 L. N. Olshan (Addressee Only)
NRC Senior Project Manager (ONS)
U. S. Nuclear Regulatory Commission Mail Stop 0-8 H12 Washington, DC 20555-0001 Mr. M. C. Shannon Senior Resident Inspector Oconee Nuclear Station
U. S. Nuclear Regulatory Commission May 19, 2003 Page 3 Table 1 Errors/Evaluation Model Changes with PCT Impact Implementation of the Void-Dependent Cross-Flow Model The previous core cross-flow model provides flow coefficients between the hot channel and the average channel.
The coefficients are fixed-valued, but specific to the flow location (above and below the mixture level) and the flow direction.
The values of the coefficients were determined by the analyst's assessment of the time variance of the fluid conditions in the channels.
The revised model adds a void-dependent transition zone (which varies in elevation with the time-dependent change in core mixture level) to interpolate the coefficient.
The interpolation of the time and level dependent fluid conditions is automated, avoiding the possible inconsistencies introduced by different interpretations between analysts.
The revised model was submitted to the NRC and approved in Reference 1. The PCT impact for this change was determined to be -12°F for the full power SBLOCA case and 0F for the reduced power (50% FP) SBLOCA case.
U. S. Nuclear Regulatory Commission May 19, 2003 Page 4 Table 2 Errors/Evaluation Model Changes with no PCT Impact Large Break LOCA (LBLOCA) Automation of the BEACH Blockage Limitation The approved version of the BEACH methodology contains a credited flow blockage limitation of 60 percent, which is implemented by the analyst inspecting the results.
A change was made to automate this limit in the BEACH coding.
This automation is more convenient and makes implementation of the limitation and calculated results more reliable and consistent.
This change was submitted to the NRC and approved in Reference 1. The nature of this change leads to an estimated PCT impact of 0F.
Fuel Surface Roughness Change A new common product specification for U02 pellets was developed to streamline the Lynchburg and Richland manufacturing practices.
This new specification is being applied to all new batches of Mark-Bil fuel.
The new specification results in a smaller fuel surface roughness.
The current Oconee Mark-Bli LBLOCA and SBLOCA calculations were evaluated and determined to be applicable to the new specification.
Therefore, the PCT impact of the change in the fuel surface roughness specification is estimated to be 0°F.
U. S. Nuclear Regulatory Commission May 19, 2003 Page 5 Table 3 Peak Cladding Temperature Summary -
Oconee Units 1, 2 & 3 LBLOCA PCT(°F)
Comments Evaluation model: RELAP5/MOD2-B&W 2037 Mark-Bll (M5), 16.8 kW/ft Analysis of record PCT At 6.021 ft elevation 2050 Mark-BlOT, 16.8 kW/ft At 4.264.ft elevation Prior errors (APCT)
- 1. None 0
Prior evaluation model changes (APCT)
- 1. None 0
Errors (APCT)
- 1. None 0
Evaluation model changes (APCT)
- 1. None 0
Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 0
Final PCT 2037 Mark-Bl 2050 Mark-BlOT SBLOCA PCT(°F)
Comments Evaluation model: RELAP5/MOD2-B&W Analysis of record PCT 1369 Full Power 0.15 ft2 break Prior errors (APCT)
- 1. Change from min to max CFT 43 Reference 2(1) level
- 2. SG primary tube region drag
-14 Reference 2 model input error
- 3. Limiting RCP type & two-phase
-5 Reference 2 degradation model(PSC 1-99)
- 4. RELAP5 water property and Unix
-25 Reference 2 operating system Prior evaluation model changes (APCT)
- 1. None 0
Errors (PCT)
- 1. None 0
Evaluation model changes (APCT)
- 1. Implementation of void-
-12 PCT determined by dependent cross flow model analysis
U. S. Nuclear Regulatory Commission May 19, 2003 Page 6 Table 3 (Continued)
Peak Cladding Temperature Summary -
Oconee Units 1, 2 & 3 SBLOCA PCT(°F)
Comments Absolute value of errors/changes for this report (APCT) 12 Net change in PCT for this report
-12 Final PCT 1356 Analysis of record PCT 1261 Reduced Power -
50% FP (1 HPI case) 0.06 ft2 break Prior errors (APCT)
- 1. None 0
Prior evaluation model changes (APCT)
- 1. None 0
Errors (PCT)
- 1. None 0
Evaluation model changes (APCT)
- 1. Implementation of void-0 PCT determined by dependent cross flow model analysis Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 0
Final PCT 1261 (1) In Reference 2 this PCT change was listed as an estimate since it was based on calculations using a model that was under review (void-dependent cross-flow model).
Given that this model is now approved, the APCT value is no longer considered an estimate.
U. S. Nuclear Regulatory Commission May 19, 2003 Page 7 bxc:
L. E. Nicholson J. S. Warren G. B. Swindlehurst R. C. Harvey M. E. Henshaw ELL E-NRC-LOCA (R. C. Harvey)
Oconee Master File, Mail Code ON03DM (File OS 801.01)