Ricerc@Sapienza

Helical coils are used for different applications across many different industries thanks to their compactness and resistance to thermal expansion respect straight tubes.
Numerous future nuclear reactors, both in fission (Generation III+ and Generation IV) and fusion projects, presently under development, are expected to use helically coiled pipes for the Steam Generator (HCSG). The improvement of such an important plant component is vital as much as the research for new technological solutions for future nuclear power plants. Indeed, they are designed to reach the goal of improved safety, performance and cost established by the world nuclear community. Numerous favorable characteristics justify the renewed interest for the helical tube SG developing in the nuclear field. In particular, helical tubes provide enhanced heat and mass transfer rates, a higher critical heat flux during boiling and evaporation and a better capability to accommodate the thermal expansion, in addition to allowing a more compact design of the SG.
An experimental campaign could improve the experience on the helical geometry. The idea is to implement a new test section into CIRCE facility in order to investigate the thermal-hydraulic behavior of a scale-down helical coil steam generator. CIRCE is a Lead-Bismuth Eutectic (LBE) pool type facility operative at the ENEA Brasimone research center. The HCSG mock-up will be implemented in the actual test section; the mock-up will be composed of a representative module of the full-scale HCSG, which will characterize the heat transfer through a helical coil geometry. For the design of the experiment and for the future design and safety analysis of DEMO reactor a new RELAP5 version will be developed, capable to analyze in a unique transient simulation all relevant phenomena: two-phase water in horizontal, vertical and helical flow maps, molten salt and liquid metals with appropriate heat transfer coefficient (HTC) and pressure drop correlations.