Speaker
Prof.
Simon Connell
(University of Johannesburg)
Description
The accurate modeling of nuclear reactors is essential for design, regulation, safety analysis, operations and forensic analysis. There are two classes of approaches to modeling the neutronics of nuclear reactors. The first is deterministic, where the neutron transport equations are solved using a combination of approximations and numerical methods based on a space-time discretization. This approach currently dominates where computing speed and resource limitations apply. The second class of models is stochastic in nature. Here many statistically independent histories for each neutron event and all secondary events related to its interactions are tracked and various physical data is stored for later statistical analysis. This paper presents several results that establish the proof of principle in the stochastic Monte Carlo (MC) modelling of a nuclear reactor core using the Geant4 framework. The simulation is exercised in the context of a High Temperature Gas Cooled Reactor (HTGCR) with pebble fuel and helium coolant. MCNP and SERPENT are better known codes in this context, however Geant4 promises to be a significant additional coding framework. It has a modern C++ modular architecture, it is multi-threaded and trivially parallel on multiple nodes, the well documented source is readily available. Rather than being input card driven the user modifies and extends the class structure. It has excellent engines for geometry, materials, physics, tracking, history recording, visualisation and the analysis is readily done with additional frameworks such as ROOT. In this paper we review the implementation of the following aspects in proof of principle form : the basic neutronics (thermailisation and containment), validation of the databases (elementary neutron induced reactions), scalability, thermal neutronics, geometrical discretisation for studying the spatial variation of physical parameters, time slicing and adaptation of Geant4 for correct intra-slice persistence, a scheme of integration with thermal hydraulics by workflow scheduling, the process of fission, burn, decay, and differential energy depositions for the various physics processes, validation of the Xenon effects on the neutronics, criticality and core follow over multiple time steps. The benchmarking programme against MCNP and Serpent is also discussed.
Level for award<br> (Hons, MSc, <br> PhD, N/A)?
N/A
Apply to be<br> considered for a student <br> award (Yes / No)?
No
Primary author
Prof.
Simon Connell
(University of Johannesburg)
Co-authors
Prof.
Anthonie Cilliers
(University of Johannesburg and Kairos Power USA)
Prof.
David Nicholls
(University of Johannesburg)
Mr
Jacobus Conradie
(University of Johannesburg)
Mr
Martin Cook
(University of Johannesburg)
Prof.
Pathmanathan Naidoo
(University of Johannesburg)
Ms
Rotondwa Mudau
(UJ)
Peer reviewing
Paper
Paper files:
