New analytical model for PWR core simulation. ASSY-CORE code system

It has already been established from detailed analysis of the PWR core that the fast neutron flux is nearly flat within the fuel assembly, and that thermal neutron diffusion is largely limited to the space between fuel assemblies. Based on these two assumptions, a new computing program has been developed for PWR core analysis, which is better than the currently used FLARE, in that it yields more accurate results with shorter computing time. The accuracy of this computer program is verified by comparison of results with measured data as well as with two-dimentional two-group diffusion calculations. (author)