Lead-Cooled Fast Reactor Annular UN Fuel Design and Development of Performance Analysis Program

Abstract

A kind of annular uranium nitride (UN) fuel suitable for lead-cooled fast reactor applications has been designed in this study. The design is directly targeting two main issues of UN fuel: severe swelling and thermal decomposition of UN fuel at high temperatures. A performance analysis program based on FORTRAN programming language has been developed for UN fuel in fast reactors. The program contains heat transfer, fuel stress-strain analysis, cladding stress-strain analysis, fission gas release and fuel-cladding mechanical interaction (FCMI) modules, etc. Extensive code verification has been performed by comparing simulation results obtained with the code and those obtained via the COMSOL Multiphysics platform. Preliminary code validation has been conducted as well by comparing code simulation results with experimental data. The results showed that this program could predict the fuel temperature, stress-strain, and displacement of UN fuel during reactor operation with a reasonable accuracy.

Study on Fuel Selection for a Long-Life Small Lead-Based Reactor

“…In response to this problem, they proposed an annular fuel design structure. The results show that the use of annular fuel design structure can effectively reduce the core temperature of the fuel, thereby solving not only the problem of fuel swelling, but also the problem of thermal decomposition [18]. Mum et al found that when U-10Zr fuel is loaded in a small lead-cooled reactor, if there is an air gap between the fuel and the cladding, the fuel centerline temperature can be as high as 2351 K, at which point the fuel will melt.…”

Non-uniform fuel distribution and thermo-mechanical analysis of a 1 MW thermal power micronuclear heat pipe reactor

“…The metallurgy and mechanical behavior of Uranium Nitride (UN) is very different from that of uranium oxides [ 13 , 14 ]. Although UN fuel has a high melting point (3120 K) it starts undergoing decomposition at about 2000K [ 15 ] due to low partial pressure of nitrogen. Thus, fuel temperature should be kept within this limit during operation.…”

“…An elaborate performance analysis for uranium nitride fuel for a lead cooled fast reactor has been carried out by Yuan et al [ 15 ] for thermal loading of 30 kW/m and 45 kW/m power densities as well as for a transient with 60 kW/m. Another similar work by Liu et al [ 17 ], carries out a thermal-hydraulic design analysis of a 500kW th 45 % enriched UN fueled MNR using potassium in a heat pipe.…”