Experience with single-channel flux synthesis calculations for three-dimensional, fast reactor models

As part of the analysis program for ZPPR critical assemblies a new computer code, SYN3D, has been used to perform spatial flux synthesis calculations of three-dimensional, diffusion theory models. SYN3D is described, as are the procedures employed in choosing synthesis expansion functions to represent core and blanket zones. Computing times for synthesis calculations seem to be roughly equivalent to the times required to generate the expansion functions. An anomaly affecting only the low-energy group fluxes was found in one of the models studied. (14 references) (U.S.)