Preliminary core characterization of a Generation IV lead fast reactor DEMO: Goals, design rationales and options

Abstract

An Italian effort has been initiated under a cooperation between ENEA and CIRTEN for the investigation of a concept for a small size Generation IV Lead-cooled Fast Reactor (LFR) demonstration project (DEMO) which could provide significant support to the European Lead-cooled System (ELSY), by validating lead technology and the overall system behaviour. A demonstration reactor is expected to prove the viability of technology for use in a future commercial power plant, construction and operation, with the purpose of assessing the general strategy to use, to the largest extent. Thus, the first step towards the DEMO conceptual design has been the specification of the issues of ELSY – assumed as reference LFR – to investigate/validate, the objectives to reach, tools and methodology. As a result, a set of general requirements that must be met have been first identified and further scope analyses have been carried out in order to determine suitable core configurations. Finally, static neutronics analyses have been performed using the ERANOS2.1 deterministic code in conjunction with the JEFF3.1 nuclear data library to accomplish a preliminary core characterization; the mutual compatibility of both objectives and technological constraints has been confirmed a posteriori by thermal–hydraulic estimations. Results have shown that a 250 MWth lead-cooled MOX-fueled DEMO may be a viable concept: in the case of 480 °C reference coolant outlet temperature, 2 m s −1 average coolant velocity and 42 cm active core extension, high neutron flux values (around 2.5 times the ELSY ones) have been obtained (peak flux: 6.3 × 10 15 cm −2 s −1 with corresponding fast fraction of approximately 15.8%, i.e., some 1 × 10 15 cm −2 s −1) thanks to the significant power densities reached.