Benchmarking MCNP and WIMS/RFSP Against Measurement Data - I: Deuterium Critical Assembly

Benchmark calculations have been performed for the conventional Canadian deuterium uranium (CANDU) core analysis code RFSP and the Monte Carlo code MCNP-4B using experimental data from the deuterium critical assembly. The benchmark calculation was carried out for the effective multiplication factor (k_eff), void reactivity, local power peaking factor (LPPF), and power distribution of a uniform core with 1.2 wt% UO₂ and two-region cores with PuO₂-UO₂ fuels. The RFSP calculation was performed with two energy groups, using lattice parameters generated by WIMS-AECL with the ENDF/B-V cross-section library. The RFSP calculation has shown that the root-mean-square (rms) errors of the k_eff and the void reactivity are within 0.6% k and 0.3% (1/k), respectively. The MCNP simulation was performed using a fully heterogeneous core model that explicitly describes the individual fuel rod and channel. The simulation showed an excellent agreement for the k_eff against the measurement, while the rms error of the void reactivity was 0.4% (1/k). The LPPF and core power distribution estimated by both codes matched those of the measurements within 4 and 9%, respectively. Conclusively, the physics analysis by the RFSP code in conjunction with the WIMS-AECL produces credible results for the light water-cooled and heavy water-moderated system. In addition, the MCNP-4B code has proved its potential as a computational benchmarking tool for the heavy water-moderated system.