Fundamental Study on Duplex Steam Generator Tubes for Liquid-Metal-Cooled Fast Reactors

For the establishment of liquid-metal-cooled fast reactors (LMFRs) as commercial reactors, one of the most important tasks is to develop highly reliable heat transfer tubes for steam generators used in LMFRs because their failure could lead to a potentially explosive sodium/water reaction. A new concept for a highly reliable duplex tube heat transfer system is proposed as an improvement over the defects of the contact-type duplex tubes and knitted wire-packed ones, which have been proposed. Small-scale duplex tubes have been manufactured. Their heat transfer rates were investigated experimentally, and an evaluation method of their effective thermal conductivity, which is required for design purposes, is proposed, where the change in contact resistance due to thermal expansion is a consideration.