The Lead-cooled Fast Reactor (LFR) has been selected by the Generation IV International Forum as one of the candidates for the next generation of nuclear reactors. LFRs adopt molten lead or lead-bismuth eutectic as primary coolant aimed at ensuring plant simplification, high operating efficiencies, potential for a closed fuel cycle thanks to the thermal, chemical and neutronics favorable features of the lead.
NRGroup collaborates since the beginning to the studies on LFRs, developed by ENEA and Ansaldo Nucleare within italian and european projects.
ADS – Accelerator Driven System
The eXperimental Accelerator Driven System (XADS) facility, was developed in Italy by a consortium of companies, universities and research centers. The project aimed at demonstrating the correct management of the sub-critical reactor driven by the accelerator as well as the feasibility of the lead bismuth eutectic (LBE) as coolant and target material, in the perspective of the ADS industrial, practical-scale applications.
The configuration of the primary system is pool-type, i.e., the core and all the primary LBE coolants are housed within the reactor vessel, which is surrounded by a safety vessel in order to ensure the containment of LBE and core cooling also in case of a reactor vessel leakage. The primary coolant, leaving the core at 400 °C, enters the riser channels at the periphery of inner vessel. Natural circulation of LBE is enhanced by argon gas injection, fed by a compressor, into the bottom part of the riser.
The secondary coolant system is made up of two independent loops, each one with two intermediate heat exchangers (IHX) immersed into the primary coolant. The secondary coolant is an organic diathermic fluid, cooled by air coolers.
ELSY – European Lead-cooled SYstem
In 2006 the European Union partially financed, within the Euratom Framework Programme 6 (FP6), the European Lead-cooled SYstem (ELSY) project.
The primary system concept studies carried out to date have led to several important design improvements resulting in a compact arrangement that features eight innovative spiral tube Steam Generating (SG) Units, eight Primary Pumps and four Decay Heat Dip Coolers installed into a vessel that is less than nine meters high.
The core consists of an array of open FAs with a square pitch surrounded by reflector assemblies, which is a configuration that presents reduced risk of coolant flow blockage.
The Steam Generator is composed of a stack of spiral-wound tubes arranged in the bottom-closed, annular space formed by vertical outer and inner shrouds.
An axial-flow primary pump, located inside the inner shell, provides the head required to force the coolant to flow radially from the inner to the outer perforated shrouds through the SG spirals tubes.
ALFRED – Advanced Lead Fast Reactor European Demonstrator
ALFRED is a small-size (300 MWth) pool-type LFR developed during the LEADER Project. All the primary components (e.g., core, primary pumps and SGs) are contained into the main reactor vessel, being located in a large pool within the reactor tank. The coolant flow coming from the cold pool enters the core and, once passed through the latter, is collected in a volume (hot collector) to be distributed to eight parallel pipes and delivered to as many SGs. After leaving the SGs the coolant enters the cold pool through the cold leg and returns to the core.