Extension of the TRANSURANUS burnup model to heavy water reactor conditions

Predictive Bias and Sensitivity in NRC Fuel Performance Codes

“…Since the original release of FRAPCON-3, a second paper has been published on the modifications to TUBRNP to correctly model HWR conditions (Lassman et al 1998). This paper stated that the original TUBRNP model could be modified to be applicable to HWR conditions if the fission and capture cross sections for each uranium and plutonium isotopes were updated based on a HWR neutron spectrum and if the constant p 1 was changed from 3.45 to 2.21.…”

Recent Updates to NRC Fuel Performance Codes and Plans for Future Improvements

“…This model has been updated in FRAPCON-3.4a to model heavy water reactor HWR conditions as recommended by the original authors of the model [10]. The predictions of this update were verified with neutronic calculations using WIMS [11].…”

“…The He production rate is a function of the number of IFBA rods in a core, and the 10 B enrichment. He is produced as the 10 B burns out until there is no more 10 B in the liners. The rate of 10 B depletion is equal to the He production rate.…”

“…The rate of 10 B depletion is equal to the He production rate. The depletion of 10 B is calculated in the code and the 10 B enrichment at the end of the time step is used to calculate the He production for the next time step. It is assumed in the code that all He produced in the ZrB2 coatings is released directly to the rod free volume.…”

Extension of the TRANSURANUS burn-up model

“…The constants p 1 , p 2 and p 3 had been derived after comprehensive comparisons with measurements of fuel slices irradiated in LWRs [6] as well as in the Halden HWR [20]. While p 1 differs between LWRs (p 1 = 3.45) and the Halden HWR (p 1 = 2.21), the values p 2 = 3.0 and p 3 = 0.45 hold for both reactor types.…”