YALINA-Booster Benchmark Analyses

The IAEA coordinated research project on the YALINA Booster facility was carried out successfully, and this project enhanced the physics understanding of the accelerator driven systems. In particular, the analyses of such systems, to define their performance, were greatly improved. The participating Member States used both Monte Carlo and deterministic computational tools for their analyses, including MCNP5, MCNPX, McCARD, and ERANOS computer programs. All the calculations utilized ENDF/B-VI (different modes) nuclear data library, except for the Korean simulations, and some of the USA analyses used the ENDF/BVII. 0 nuclear data libraries. Generally, there is good agreement between the results obtained by all the Member States. The USA deterministic analyses required space, energy, and angle discretization, and materials homogenizations, which introduced major approximations because of the severe heterogeneity of the YALINA-Booster geometry. Another challenge for the deterministic model is the presentation of thin absorber layers between the different zones. Such issues affected the accuracy of the USA ERANOS results. The 90% enriched uranium fuel in the fast zone of YALINA-Booster facility was replaced with 21% enriched uranium fuel without affecting the facility performance. Additional EK10 fuel rods were added in the facility thermal zone to maintain the facility subcriticality level. In the YALINA-Booster facility, decreasing the fuel enrichment reduces the difference between the effective and the source multiplication factors. This difference becomes negligible when the 21% enriched uranium fuel is used for the californium and D-D neutron sources. The neutron leakage from the YALINA Booster facility did not change when the uranium fuel enrichment was reduced in the fast zone around the external neutron source. The large assembly size, and locating the external neutron source at the assembly centre, reduces the neutron leakage. In YALINA-Booster configurations with low effective multiplication factor, i.e. YALINA-Booster configuration with 902 EK10 fuel rods in the thermal zone, the time dependent reaction rates from a single D-D or D-T neutron pulse reach an asymptotic value produced by the delayed neutrons. For the YALINA Booster assembly, the comparison between analytical and experimental neutron multiplication factor values exhibits differences of 450, 700, and 650 pcm for the 90%-, 36%-, and 21%-enriched uranium fuel configurations, respectively. However, when the ²³⁴U isotope concentration, EK10 fuel impurities, and the detector dead time are taken into account, the previous differences diminish to less than 50, 350, and 350 pcm, respectively.