Equipoise-2, a two-dimensional, two-group neutron-diffusion code in R-Z geometry, has been programmed for the IBM-7090 computer. This code was designed to permit the running of large numbers of cases without requiring excessive machine time. Typical running times are of the order of one to three minutes per case for a 1000-point problems. The maximum number of mesh points that can be used is 1444.

The following report describes a mass flow system that can measure homogeneous flow, slurries, highly corrosive fluids and multiphase fluids, with the addition of considering pressure drops, measuring external to the flow, ruggedness and reliability.

Departures from the usual precipitation method produced crystalline uranium peroxide in several forms. Three types of segregated needles were used in the preparation of three pellets for pellet-type elements. Densities of the pellets ranged from 93 to 97% of theoretical, depending on conditions of precipitation.

The ORNL analog computer was used to simulate four widely different experiment conditions in the small EGCR in-pile loops. Various control and safety systems were evaluated in each case. Curves are included which show the response to postulated accidents and component failures. The results indicate that one standard control and safety system will probably be adequate for a wide variety of test conditions.

The Hanford water treatment plants were operated for a number of years with alum as a coagulant and activated silica as a coagulant and a polyacrylamide as a filter conditioning agent. (other polyelectrolytes may be used.) Sufficient time has elapsed to make a comparison of the two methods of operation valid and useful. Such a comparison is the purpose of this paper.

The need for criticality control in the proposed reprocessing of slightly enriched non-production fuels at Hanford has led to the development of a geometrically "safe", vertical tube, recirculating dissolver. A study of the nitric acid dissolution of uranium dioxide in a pilot plant dissolver of this type is reported here. The study was pointed toward the comparison of uranium dioxide dissolution rates in a batch and a recirculating dissolver and the definition of hydraulic problems associated with the recirculation of nitric acid, by air lift, technique through beds of reacting uranium dioxide.

In a gas-cooled reactor operating at very high power density the thickness of the reflector may be determine by the requirement that the steel pressure vessel be protected from an excessive dose of fast neutrons, rather than by the usual requirements of neutron economy and power distribution. It is important the the reflector not be made thicker than necessary, since an increase in pressure vessel diameter can result in a marked increase in cost, as well as a decrease in the permitted gas pressure level.

Work during this report period includes a continuation of the study of the effect of krypton 85 on the polymerization of styrene; an attempt at evaluation of the polymers produced; and the effect of krypton radiation on the electrical properties of gases, such as the rare gases, and nitrogen, and oxygen. the results obtained are summarized in the report.