Summary of JUPITER program

This paper is described on the outline of JUPITER program which is a joint program between Japan and US for the development of the nuclear design method for large fast breeder reactors. The purpose of the program is to obtain information concerning the nuclear properties of two-region homogeneous reactors by using a large size reactor, to investigate into the size effect on the characteristics and to estimate the accuracy of present analytical method. The reactor for the present program is ZPPR of ANL. This is a horizontally divided critical assembly. The standard fuel material is Pu-U-Mo alloy. The measurement of the various kinds of reactivity was made by the inverse kinetics technique. A basic equation of dynamic characteristics was introduced, and analysis was made by the equation. As the results of studies, it was found that the overall nuclear characteristics of a large homogeneous reactor was obtained, the agreement between calculated values and experimental values on the output distribution, Na void effect and control rod worth was not good, and the experimental values of the radial direction distribution of neutron flux shifted from the calculated values systematically. (Kato, T.)