Annular fuel pin heat transfer and lumped model correction

A new modified lumped heat transfer model is developed to calculate the annular fuel pin's average temperature by considering the central hole. Lumped heat transfer methodology is simple, and the solution is very fast, so it consumes smaller computational time. Lumped heat transfer assumes the fuel pin is solid and the thermal conductivity across the fuel pin is constant. In the present work modification are done on the heat resistance term so that information about the central hole is considered in the lumped heat transfer model. Transient analyses are carried out for a typical LMFBR's annular fuel pin with the modified lumped heat transfer model. The results are found to be matching well against the numerical schemes like the Crank–Nicolson's method for any kind of reactivity inputs. The methodology can be used in nuclear reactor simulation studies and in conservative accident analyses where fastness of the solution is a matter of concern.