Development of the HEXACOM Facility for Characterising the Heat Transfer Performance of the MYRRHA PHX in LBE

The Multi-purpose HYbrid Research ReActor (MYRRHA) is a 100 MWth pool-type fast-spectrum research reactor cooled by Lead-Bismuth Eutectic (LBE) under development at SCK•CEN. MYRRHA’s Primary Heat eXchangers (PHX) represent the most important interface between the nuclear island and the secondary water-steam system since they are located inside the reactor’s pool. Recent PHX design updates employ a double-wall bayonet tube bundle coupled with a leak monitoring system for improved safety. This technology has been used in industry for many years and proposed for nuclear applications since the 1960s. Nevertheless, a thorough demonstration of its performances and reliability are not readily available. SCK•CEN launched an experimental Research and Development (R&D) programme to close this R&D gap. Among the envisaged facilities, the existing COMPonent LOop Testing (COMPLOT) LBE loop type facility will be coupled to the recently constructed Heat EXchAnger at COMplot (HEXACOM) water/steam loop, to test a single tube Primary Heat eXchanger (PHX) representative of MYRRHA (full scale). This paper aims to introduce the PHX test section and the HEXACOM facility, together with the preliminary T-H system code (RELAP-5 mod3.3) analyses conducted in support to the design of experiments. The main focus is given to the performances of the double wall bayonet tube PHX with leak monitoring system based on pressurized helical cavities.