MEASUREMENTS OF REACTOR PARAMETERS IN SUBCRITICAL AND CRITICAL ASSEMBLIES**The work involved in the preparation of this review was supported, for the most part, by the United States Atomic Energy Commission

Publisher Summary This chapter describes the measurements of reactor parameters in subcritical and critical assemblies. There are two types of experimental assemblies namely—exponential and zero-power critical. In practice, the use of these assemblies may be expensive and time consuming. A method that reduces the material requirements of the usual exponential or critical experiment is the substitution or two-region critical experiment used mainly for the measurement of the critical buckling. The values of the disadvantage factors and the thermal utilization obtained in subcritical assemblies seem to agree, and to give values appropriate to a critical assembly. The disadvantage factors, however, depend on averages of flux distributions and cross sections, and are less sensitive to differences in neutron energy distribution than the spatial distribution of the neutron density; the thermal utilization is still less sensitive. An attempt has been made to determine lattice parameters by means of measurements on a single fuel element.