HELIOS2

As part of the verification program for the HELIOS2 code system, examination of the B&W-1484 and DIMPLE S-06 critical experiments was performed. Detailed computation models were developed for both experiments. Core eigenvalues and reaction rates, where available, were compared; after accounting for various biases and uncertainty, the results are generally excellent.

The critical experiments performed at the Hungarian ZR-6 reactor and experiments performed at General Purpose P (GPP) critical facility at RRC “Kurchatov Institute” are used to benchmark HELIOS-2, as part of its ongoing validation and verification activities. The comparisons presented in this paper are based on, ZR6-VVER-EXP-001, Vol. 1 (2007), LEU- COMP-THERM-015, Vol. 4 (2005), and LEU-COMP-THERM-061, Vol. 4 (2002).

On ZR-6, single cell, macro cell, and 2D calculations on selected experiments, regular and perturbed, are made. In the 2D calculations, the radial leakage is treated by including the reflector in the calculations, representing only axial leakage by a measured axial buckling. keff and RMS reaction rates comparisons are presented.

On GPP critical facility, the entire experiment is modelled as 2D. Comparisons of keff and fission rates are presented and the effect of the axial buckling on keff is investigated.

Major advances have been made in the HELIOS code, resulting in the impending release of a new version, HELIOS2. The new code includes a method of characteristics (MOC) transport solver to supplement the existing collision probabilities (CP) solver. A 177-group, ENDF/B-VII nuclear data library has been developed for inclusion with the new code package. Computational tests have been performed to verify the performance of the MOC solver against the CP solver, and validation testing against computational and measured benchmarks is underway. Results to-date of the verification and validation testing are presented, demonstrating the excellent performance of the new transport solver and nuclear data library.

Major advances have been made in the HELIOS code, resulting in the impending release of a new version, HELIOS2. The new code includes a method of characteristics (MOC) transport solver to supplement the existing collision probabilities (CP) solver. A 177-group, ENDF/B-VII nuclear data library has been developed for inclusion with the new code package. Computational tests have been performed to verify the performance of the MOC solver against the CP solver, and validation testing against computational and measured benchmarks is underway. Results to-date of the verification and validation testing are presented, demonstrating the excellent performance of the new transport solver and nuclear data library.