Calculations over the AECL HCE3 H01 and H02 FP Release Experiments with the ASTEC Version 1.3 rev0 Reactor Code

Calculation of FP release from U02 fuel in different atmospheres and temperatures was performed over the H01 (steam) and H02 (air) HCE3 experiments conducted at AECL, Chalk River Laboratories, using irradiated sheathed segments of CANDU fuel. The aim was testing the FP release model included into the ASTEC version 1.3 rev 0 over small-scale experiments performed under different environments and temperatures leading to fuel oxidation/vaporisation. experiments in steam atmosphere calculations far Ruthenium release concord very well with data while the volatiles are somehow overvalued, though remain within the range of experimental uncertainties. For air ingress experiments, on the contrary, the volatile FP releases find very good agreement with experimental data while no ruthenium release is calculated by the code. Besides neither Ba release nor U02 vaporization was obtained by calculations aver the H02 experiment. We can conclude that calculations find good fit with experimental data far volatile FP releases in both steam and air atmospheres. Excellent fit is found far less volatile FP releases in the steam atmosphere experiment whilst far tests in air environment less volatile FP calculated releases are zero or almost zero, the same as for urania fuel vaporization/volatilization. This may be due to the fact that within ELSA/DIVA models air flow in the channel must at the moment be represented as a N2 O2 mixture in the code input and perhaps there is still some maladjustment in the model.