Thermohydraulic Simulation of Energy Well Micro Modular Reactor Using System Codes

Abstract Due to the actual energy need worldwide, which should be carbon oxide emission free, several initiatives to prepare advanced Small Modular Reactor (SMR) and Micro Modular Reactors (MMR) are ongoing in order to offer new energy solutions (not only for electrical production) with high standard in safety. The goal of these technologies is to obtain clean energy with low carbon emission, which will be located nearby industries or cities. In particular, several countries such as United States of America, Great Britain and Canada plan to build a fleet of SMRs in order to find a compromise between, the actual energy needs, the construction period and investment cost. Particular attention is given to the Gen. IV reactors, which are bringing new solutions and aspects in the nuclear panorama. One of the goals is the practically elimination of severe accident addressed by approaches and phenomena, which are considered during the design of SMRs and MMRs. For this reason, the SMRs development is conditioned by a portfolio of technological solutions, which are currently in preparation, and by the readiness of the supervisory authority to legislatively regulate the construction, operation and supervision. One of these concepts is Energy Well (EW), an MMR developed in Centrum Výzkumu Rez (CVR) located in the Czech Republic with support of a national consortium, which includes universities and other Czech companies. Especially, CVR uses its experience of more than 60 years in running research reactors, which has several similarities with MMRs, to design EW and to build several facilities useful to assess the molten salt technology. Several activities are ongoing in a framework of a project financed by the Technologická agentura České republiky (TAČR). Part of these activities focuses on thermohydraulic assessment and safety analyses, which are performed by CVR and Nuclear Research Institute (UJV) in a parallel benchmark activity. The codes used in these activities are TRACE 5 patch 7 developed by Nuclear Regulatory Commission (US NRC) and RELAP5-3D developed at Idaho National Laboratory, which offer several working fluids represented in different equation of states. The aim of the analyses is to provide the results of a benchmark, particularly, assessing the capability of TRACE and RELAP to analyze molten salt technology. Additionally, the EW thermohydraulic will be investigated starting from the steady state and reaching a transient analysis. Particular attention will be given to the point kinetic module, which is introduced and implemented into the models to study the core behavior under extreme accident conditions.