Márk Margóczi, Dávid Légrády (2022.08.01 - 2022.12.31)

Budapest University of Technology and Economics

Grant: NKFIH 2020-2.1.1-ED-2021-00179

Abstract: Neutron transport calculations of dynamic Monte-Carlo method is emerging new area of research in the nuclear science. The dynamic Monte-Carlo calculation cannot only be used to foretell neutron kinetics, but to enable more complex dynamic simulations, it can also be coupled with thermal-hydraulic codes. The coupled calculation method raises questions of stability and convergence.

GUARDYAN (GPU Assisted Reactor Dynamic Analysis) is a dynamic Monte Carlobased neutron transport code. The GUARDYAN is able to calculate neutron kinetics, but for more complex reactor physics calculations thermal-hydraulic feedback becomes necessary. To achieve the desired calculations the GUARDIAN has been coupled with a SUBCHANFLOW sub-channel flow simulation code. The simplest tool for testing stability and convergence is the stochastic calculus, within the framework of which neutron kinetics can be approximated with a stochastic differential equation. If the variance contribution term of the equation is defined with Monte-Carlo assumptions, then the stochastic differential equation approximates the dynamic Monte-Carlo method simulation. If the problem is sufficiently simple, the neutron kinetics and thermal-hydraulic of the rector can be derived using analytical formulas. In order to calculate expected value, standard deviation and variance with adequate statistical uncertainty corresponding to the method, these equations must be compared with the solutions of practical problems which require numerous simulation.

Application of GPU cluster supports the publication of scientific journal articles, topic of which is the mapping of the relationship between stochastic differential equations and time-dependent Monte-Carlo-based neutron transport and the investigation of the spread of variance of stochastic neutron kinetics to variance of thermal-hydraulic.