Application of Deterministic Codes for Transient Analyses in Accelerator Driven Systems

Abstract

Accelerator Driven Systems (ADSs) have been studying since long as a promising option for waste transmutation and energy production. In ADS the use of an external source causes the flux profiles to be different from the fundamental mode which characterize the critical reactors. These spatial effects are of interest to analyse for improving the accuracy and reliability of nuclear data and codes. In particular, validation of the kinetics models employed by the deterministic codes which are embedded in the safety codes is of great importance. The aim of the thesis is to analyse the capabilities of the deterministic codes to predict the static and time-dependent detector responses from an external neutron pulse of two core configurations at different subcritical levels of Kyoto University Critical Assembly (KUCA), located at the Kyoto University Research Reactor Institute (KURRI). The aim was also to predict the experimental results of the application of the Pulsed Neutron Source (PNS) area method for reactivity inferring. The current work is performed in the framework of the participation of KIT to the calculation benchmark launched by the KURRI, on the analysis of the Phase-I kinetics experiments performed at KUCA. This is done in the frame of the IAEA Collaborative work on ‘Accelerator Driven Systems (ADS) and Use of Low-Enriched Uranium (LEU) in ADS’. A 3D (XYZ) model of KUCA configurations and self-shielded multigroup cross sections were processed by means of the European Cell Code (ECCO). The 3D transport calculation has been performed by means of the European Reactor ANalysis Optimized System (ERANOS) and PARallel TIme-dependent SN code (PARTISN). The simulation results were compared with the reference experimental data in means of criticality level and kinetic parameters. Furthermore, were the codes employed to analyse the experimental results coming from the application of PNS area method. Transient simulations were performed with KIN3D/VARIANT and KIN3D/PARTISN deterministic codes, with the purpose of analysing the time-dependent detector responses to an external neutron pulse. Calculation results show a good agreement with the kinetic experiments from KUCA. In particular, were the codes able to reproduce the reference PNS results and the experimental transient.