ROCOCO system of combined neutron constants – current status and results of testing using geometrical module of the MMK code

Results of studies aimed at the further refinement of the ROCOCO system (routine for calculation and organization of combined constants including cross-sections in group and subgroup representation with detailed description of energy dependence of neutron cross-sections) (Zherdev et al. 2018, Kislitsina et al. 2016) are presented in the paper. Inclusion of this system as a physical module into a set of Monte Carlo calculation codes with OOBG geometric module from the MMK code (Zherdev et al. 2003) is discussed. OOBG module is designed for calculation of neutron multiplication systems with heterogenous cores arranged as hexagonal grids with different degrees of complexity. The name ROCOCO-MMK was assigned to the complex. Results of testing the complex in the calculations of multi-zone neutron multiplication systems (including those with zones containing neutron moderator, zones with close composition but with different temperature, etc.) are described. Accounting for the dependence of constants for one and the same nuclide in the zones with different compositions and temperatures required substantial modernization of routines for preparation of constants for calculation described in (Zherdev et al. 2018). Algorithm for preparation of subgroup constants was modified, methodology for taking into account resonance self-screening of cross-sections within the range of unresolved resonances was improved, and other changes were introduced in the process of this modernization. Results of calculations are compared with data obtained using the MCNP-5 precision program (MCNP 1987), which is linked to the same library of evaluated neutron data ROSFOND as that used in ROCOCO. The ROCOCO-MMK includes procedures for registering different neutron flux functionals (also based on ROCOCO data), which allowed including it in the SCALA computation complex (Zherdev et al. 2003, Zherdev 2005), and performing step-by-step calculation of evolution of fuel nuclide composition during the fuel residence campaign. Directions for further development of the system are outlined in conclusion and, in particular, some possibilities of using the created software for further improvement of methods for preparation of few-group constants for calculations in diffusion approximation are examined.

Reorienting When Cues Conflict

Proponents of a geometric module claim that human adults accomplish spatial reorientation in a fundamentally different way than young children and non-human animals do. However, reporting two experiments that used a conflict paradigm, this article shows striking similarities between human adults and young children, as well as nonhuman animals. Specifically, Experiment 1 demonstrates that adults favor geometric information in a small room and rely on features in a larger room, whereas Experiment 2 demonstrates that experience in a larger room produces dominance of features over geometric cues in a small room—the first human case of reliance on features that contradict geometric information. Thus, use of features during reorientation depends on the size of the environment and learning history. These results clearly undermine the modularity claim and the view that feature use during reorientation is purely associative, and we discuss the findings within an adaptive-combination view, according to which a weighting system determines use of feature or geometric cues during reorientation.