Subchannel analysis with turbulent mixing rate of supercritical pressure fluid

• Subchannel analysis with turbulent mixing rate law of supercritical pressure fluid (SPF) is carried out.
• Turbulent mixing rate is enhanced, compared with that calculated by the law of pressurized water reactor (PWR).
• Increase in maximum cladding surface temperature (MCST) is smaller comparing with PWR model.
• The sensitivities of MCST on non-uniformity of subchannel area and power peaking are reduced by using SPF model.

The subchannel analysis with turbulent mixing rate law of supercritical pressure fluid (SPF) is carried out for supercritical-pressurized light water cooled and moderated reactor (Super LWR). It is different from the turbulent mixing rate law of pressurized water reactor (PWR), which is widely adopted in Super LWR subchannel analysis study, the density difference between adjacent subchannels is taken into account for turbulent mixing rate law of SPF. MCSTs are evaluated on three kinds of fuel assemblies with different pin power distribution patterns, gap spacings and mass flow rates. Compared with that calculated by employing turbulent mixing rate law of PWR, the increase in MCST is smaller even when peaking factor is large and gap spacing is uneven. The sensitivities of MCST on non-uniformity of the subchannel area and power peaking are reduced.