Prediction of coolant temperatures and fluid flow patterns within a TRIGA reactor core using RELAP5/Mod 3.3 and COMSOL codes

The Geological Survey TRIGA Reactor (GSTR) is a 1 MW Mark I TRIGA reactor built in 1969 and located at the Denver Federal Center (DFC) in Lakewood, Colorado. This paper studies the effects of incorporating coolant cross-flow in thermal hydraulics models on prediction of coolant temperatures and fluid flow patterns in the GSTR core. To fully understand these effects, this paper compares coolant temperatures and fluid flow patterns predicted by four thermal hydraulics models built for the GSTR which are: RELAP5/Mod 3.3 single channel, RELAP5/Mod 3.3 multichannel, COMSOL single channel, and COMSOL multichannel models. Due to addition of coolant cross-flow, multichannel model s results remarkably vary in coolant temperatures and fluid flow paths than single channel model s results. Finally, the major differences in results between all developed thermal hydraulics models of the GSTR are highlighted. (Author)