ML20127H257
| ML20127H257 | |
| Person / Time | |
|---|---|
| Site: | Framatome ANP Richland |
| Issue date: | 01/11/1993 |
| From: | Copeland R SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| RAC:93:007, RAC:93:7, NUDOCS 9301220270 | |
| Download: ML20127H257 (4) | |
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I SIEMENS
- January 11,1993 RAC:93:007 Director of Nucioar Reactor Regulation U. S. Nucioar Regulatory Commission Mall Station P1-137 Washington, D.C. 20555 Attention: Document Control Desk Annual Reporting of Changes and Errors in SPC ECCS Evaluation Models Attached is a description of the minor changes and errors in the loss of coolant (LOCA) ovaluation models over the past year. This description is required by 10 CFR 50.46. This -
report covers the period from Octobor 1991 to the present. SPC usos the EXEM BWR -
Evaluation Model for boiling water reactor largo and small break LOCA ovaluations, the EXEM PWR Evaluation Model for pressurized water reactor largo break LOCA evalue.tlons, and tho-ANF RELAP Small Break Model for pressurized water reactor small break LOCA ovaluains.
It should be noted the SPC consicers LOCA models to be the codes and the methodology for using those codos. Changas to inputs that result from fuel or plant changes and that are treated according to the methodology are not considered model changes and thorofore are not reported in the attachmont. These input changos are evaluated on a plant specific basis in accordance with the other sections of 10 CFR 50.
if there are any questions, or if further information is nooded, please contact me.
j Vory truly yours, f4 u R. A. Copeland, Manager Product Ucensing
/smg Attachment cc:
Mr. R C, Jones (USNRC) 210120 Siemens Power Corporation Nuclear Division f lineering and Manufacturing Facility 2101 Horn Rapids head. PO Box 130. RicNand. WA 993524130 Tel: (509) 3754100 Fax: (509) 375-8402
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' Attachment to RAC;93:007 Page 1 Annual Reportino of EXEM BWR Minor Model Chanaes.
and Minor Error Corrections There nas been one minor correction made in the RODEX2 code. The RODEX2 code is used to establish the fuel rod conditions (e.g., stored energy, fission gas release, etc.) at the start of the LOCA transient. The change that was made was to correct the formulation for the treatment of the pellet accommodation (SWMDEN) of the swelling for values other than the default value. When using the default value, the code proporly computed the pellet growth. If other values were input, based on the pellet manufacturing requirements, the code logic was incorrect and the swelling as a function of exposure time wouid be overpredicted. The correction changes the code so that the swelling is treated consistent with the description provided for the NRC review. The correction does not affect past analyses because these analyses used the default value. The correction precludes the likeliho_od of an error in futuro analyses. Therefore, 9 is no impact on the peak cladding temperature.
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Altachment to RAC:93:007 Page 2 Annual Repofi_ng of EXEM PWR Minor Model Chances and Minor Error Corrections Thoro has boon one minor correction mado in the RODEX2 code. The RODEX2 code is used --
to establish the fuel rod conditions (e.g., stored energy, fission gas release, etc.) at the start of the LOCA transient. The chango that wac made was to correct the formulation for the treatment of the pollet accommodation (SWMDEN) of the swelling for values other than the default value. When using the default value, the code properly computed the pollot growth. If other values were input, based on the pollet manufacturing requirements, the codo logic was-incorrect and the swelling as a function of exposure time would be overprodicted. The correction changos the code so that the swelling is treated consistent with the descrip' ion provided for the NRC review. The correction does not affect past analyses because these analysos used the default value. The correction precludes the likelihood of an error in future analysos, Thorofore, there is no impact on the peak cladding temperature.
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" Attachment to RAC:93:007 Page 3 Annual Reportina of ANF-RELAP SBLOCA Model Minor Chances and Minor Error Corrections There has been one minor correction made in the RODEX2 code. The RODEX2 code is used to establish the fuel rod conditions (e.g., stored energy, fission gas release, etc.) at the start of the LOCA transient. The change that was made was to correct the formulation for the treatment of the pellet accommodation (SWMDEN) of the swelling for values other than the default value. When using the default value, the code properly computed the pellet growth. If other values were input, based on the pellet manufacturing requirements, the code logic was incorrect and the swelling as a function of exposure time would be overpredicted. The correction changes the code so that the swelling is treated consistent with the description provided for the NRC review. The correction does not affect past analyses because these analyses used the default value. The correction precludes the likelihood of an error in future analyses. Therefore, there is no impact on the peak cladding temperature.
An error was identified in the TOODEE2 code programming of the Dittus-Boelter correlation.
The TOODEE2 code is used to compute the heatup of the hot rod given the system boundary conditions from ANF-RELAP. The error involved using the film conditions to evaluate fluid properties instead of the bulk fluid conditions required by the correlation. The impact of this error was a 2 F decrease in the peak cladding temperature.
The Dittus-Boelter correlation was also programmed incorrectly in the ANF-RELAP code. The programming error was the inclusion of an extra asterisk in the correlation, which resulted in a number less than one being raised to a large power, thus producing a heat transfer coefficient of essentially zero. The code selects the maximum heat transfer coefficient from either the Dittus Boetter Correlation, a natural convection correlation, or a value equivalent to a Nusselt Number of 4.36. Because the SBLOCA event involves primarily natural circulation flow rates in the primary system, differences in a heat transfer coefficient calculated by any of the three methods mentioned would be quite small and the magnitudes would range from about 10 to 50 BTU /hr-ft' *F. The thermal conductivities of the various heat structures in the primary system are low and the convective heat transfer coefficients are low. Therefore, differences in heat transfer rates from the structures to the coolant would be expected to be very small. Thus, the effect of the code error is judged to be insignificant and well within a 50*F peak cladding temperature impact.
Invalidation of the Dougall Rohsenow correlation is not applicable for the SPC SBLOCA model because the model does not use this correlation.