A simplified stochastic model based on the forward stochastic model in the stochastic kinetics theory and the Itô stochastic differential equations is newly developed for treating monoenergetic space-time nuclear reactor kinetics in one dimension. The stochastic space-dependent kinetics model (SSKM) is tested against the Monte Carlo calculations for cases of uniform slab reactors with one delayed-neutron precursor group. The results show that the SSKM is in good agreement with the Monte Carlo method and can be used to describe the actual random space-time-dependent behavior of a nuclear reactor. Moreover, the SSKM can generalize the stochastic point-kinetics model.

In previous studies, a simplified stochastic model (called the stochastic space-dependent kinetics model, SSKM) based on the forward stochastic model in the stochastic kinetics theory and the Itô stochastic differential equations was developed for the analysis of monoenergetic space-time nuclear reactor kinetics in one dimension. However, the behavior of the dynamic variations under a transient condition that plays a crucial role in operational and safety controls of nuclear power reactors has not been explicitly analyzed using this model. In this work, a numerical investigation is made using the SSKM in order to observe the random oscillations in population dynamics following various transients in subcritical and supercritical reactors. The results, which appear plausible on a physical basis, demonstrate that the behavior of the stochastic neutron and precursor distributions within a reactor can be induced using the SSKM.

EASYQAD version was developed by MATLAB GUI (Graphical User Interface) as a visualization code system based on QAD-CGGP-A point-kernel code for convenient shielding calculations of gammas and neutrons. It consists of four graphic interface modules including GEOMETRY, INPUT, OUTPUT, and SHIELD. These modules were compiled in C++ programming language by using the MATLAB Compiler Toolbox to form a stand-alone code system that can be run on the Windows XP operating system without MATLAB installation. In addition, EASYQAD version has user-friendly graphical interfaces and, additionally, many useful functions in comparison with QAD-CGGP-A such as common material library, line and grid detectors, and multi-group energy calculations so as to increase its applicability in the field of radiation shielding analysis. It is a powerful tool for non-experts to analyze easily the shielding problems without special training. Therefore, EASYQAD version is expected to contribute effectively to the development of radiation shielding analysis by providing users in medical and industrial fields with an efficient radiation shielding code.