SPAYCOR: SPrAY COoling of the Reactor lower head
SPAYCOR is a multi-nozzle upward spray cooling facility is being designed to obtain high critical heat flux (CHF) margins on a reactor pressure vessel (RPV) steel samples for application to in-vessel melt retention strategy for high power nuclear reactors. The tests can be performed at different specimen orientations that representing reactor vessel lower head.
The main subject of this work is to run the tests up to a maximum surface heat flux density of 4 MW/m2 to develop an empirical model for the critical heat flux on basis of spray characteristics. This facility is composed of 3x2 array nozzle assembly, SA533B1 steel specimen, coolant supply loop, 75 kW DC power supply unit, and liquid and steam withdrawal loops. The heating method adopted here is electric resistance heating through a thin film of heater atop of steel via dielectric film. The DC power supply unit provides the required heat load in the heater film and it diffuses to the working surface. The size of the RPV specimen considered for the steady is 120 mm x 80 mm.
An infrared camera is mounted on rear side of the surface to get real-time temperature data and several temperature sensors as well and a confocal-sensor on front surface to measure the microlayer thickness during spray cooling. A pump to supply required coolant flow and some K-type thermocouples are positioned to obtain inlet and outlet water temperatures, as well as steam temperatures inside the chamber. A digital flow meter measures the nozzle flow per outlet and a multi-variable vortex flow meter measures the generated steam flow. Pressure transducers are arranged to monitor the flow pressure, chamber pressure, etc. A condenser is located to suppress the outlet steam.
