Soluble Neutron Absorbers and Experimental Data for Criticality Control

Soluble Neutron Absorbers and Experimental Data for Criticality Control 

A Survey of Experimental Criticality Data Concerned with Soluble Neutron Absorbers, 

Subcommittee 8, Fissionable Materials Outside Reactors, of the Standards Committee of the American Nuclear Society is concerned with the development of standards that establish criteria for nuclear criticality safety in all parts of the nuclear fuel cycle except in reactor cores. This Subcommittee has established a Work Group charged with developniient of a standard concerned with the use of soluble neutron iabsorbers—or poisons—for criticality control of solutions containing U, or Pu. 

There is a paucity of experimental dah in both homogeneous and heterogeneous categories. For the and the clean, simple solutions, the only directly applicable data are those of Gwln and Magnuson. These data were generated as a part of the reevaluation of the value of eta In the late 1950 s. The relevant measurements were made in unreflected spherical vessels of two 

Lloyd et al. report critical data for water-reflected cylinders of plutonium nitrate to which measured quantities of gadolinium pitrate were added to Increase the solution critical height. Two plutonium concentrations were used, and sufficient gadolinium was added to produce an approximately fivefold increase in critical mass in the case of the lower plutonium concentration and to approxipiately double the critical mass of the higher concehtrailph Analysis of these data indicate that the effect qf neutron absorber decreases 

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