RELAP fuel rod-coolant response modeling

[Vnt666Skr]

Hi,
I am a beginner with the use of relap. So this might be a bit silly. I am studying the heat transfer between a fuel rod and a single channel of coolant. One of the inputs for the heat structure is the direct moderator heating multiplier. What is that and how do I find its value?

Thanks. Any help or advice will be greatly appreciated.

 

[QuantumPion]

I presume that is the fraction of heat delivered directly to the coolant, i.e. from neutrons and gamma rays. This is generally a constant only dependent on reactor type. For PWR's we use 97.4% for fraction of heat generated in the fuel (moderator would thus be 2.6%).

 

[Vnt666Skr]

Thanks QuantumPion ! :)

 

[Hologram0110]

I presume that is the fraction of heat delivered directly to the coolant, i.e. from neutrons and gamma rays. This is generally a constant only dependent on reactor type. For PWR's we use 97.4% for fraction of heat generated in the fuel (moderator would thus be 2.6%).

I know for CANDU's we normally use a value of 92.5% heat-to-fuel/energy released. It is interesting that it is so much lower than PWR's. Presumably this is because LWRs have a higher ratio of fuel in the core.