Our research proposal, “Simulation of transients in sub-critical and critical assemblies using Monte-Carlo method and its validation with in-core measurements”, which has been submitted to the The Ministry of National Infrastructures, Energy and Water Resources (public tender 14/4) has been accepted by the Ministry chief scientist and approved for funding.
The proposed research is carried out in close collaboration with researchers from the Nuclear Research Center NEGEV (NRCN), and will be granted 245,000 NIS for a period of three years.
Following is the proposal abstract:
Research Objectives: This research will focus on the simulation of transient processes in a reactor combined with experimental validation measurements. These processes characterize the convergence towards stabilization as well as leaving the stable regime either in controlled normal operation or in accident scenarios. Changes in the reactor materials, geometries or temperature will be manifested in a fast change of the neutron flux in the reactor core. The research objectives are to improve the prediction and measurement of such instabilities.
Methodology: Core calculations are carried out based on two techniques: deterministic and Monte-Carlo. Both techniques provide fairly limited capabilities to describe these processes. The research will focus on transforming the Geant4 simulation toolbox, originally developed for the elementary particle physics community, into reactor neutron flux calculations. The choice of Geant4 benefits from two advantages: A. It is a proved validated code in the field of ionized radiation and nuclear physics which is used in a variety of applications in basic science as well as commercial products. B. It is an open source code which allows potential changes and evolution of materials and geometries. The motivation is to create a flexible tool which from first principle will calculate macroscopic quantities such as K_eff or mean generation time. Since the present codes are known to have limited success in the transient scenarios, this research will use actual measurements for validation either in Soreq reactor or other research reactor. To this end, both Self Power Neutron Detectors (SPND) and miniature Fission Chambers (FC) will be used. These detectors will allow measurements of local and temporal neutron flux in the core.
Benefits to the energy ministry goals: The simulation and measurements of transient processes in the reactor have wide implications on the current reactor safety policy as well as on future design of reactor with improved inherent safety capabilities. This research supports the control system of reactor by combining the fast local neutron detector in the core, combined with theoretical tools to predict the core behavior at each scenario.
Possible applications: For all future nuclear power reactors in Israel, the measurements methods, detectors and theoretical tools will contribute to the optimal design, combining high efficiency for energy production with high fidelity safety operation.