This work develops a plate-fueled reactor subchannel steady state heat transfer code (PFSC) using a one-dimensional subchannel model. Verification and Validation is done for the PFSC by deriving several key equations, which are used in the subchannel heat transfer analysis, from the Reynolds Transport Theorem. This activity allows the subchannel model to be extended to include uncertainties and biases associated with the modeling simplifications. The initial basis for the development of the subchannel code is the High Flux Isotope Reactor (HFIR), which is a leading example of a high...