SPACERS TO PROTECT AGAINST DNB IN HIGH THERMAL PERFORMANCE BOILING WATER NUCLEAR REACTOR FUEL ASSEMBLIES OR SIMULATION EXPERIMENTS.

摘要

Ferrule type spacers are spaced one from the other along a nuclear fuel bundle for a boiling water reactor. The ferrules of the spacers in the two-phase region of the BWR are configured to provide high flow resistance and hence low velocity to thicken liquid coolant films about the fuel rods downstream of the spacer to raise critical power performance before a boiling transition occurs. In the lower region of the reactor, the spacers are configured to have a minimum resistance to flow of coolant and hence provice a high velocity flow about the fuel rods inmediately downstream of the spacers to avoid a departure from nucleate boiling.