This document from Savannah River Plant reports progress for June 1955 in the 100, 200, 300, and 400 Areas. Information is presented on the assembly area, reactor control, reactor complex, and disassembly for the 100 Area (reactors). From the 200 Area (separations plants), progress at the solvent extraction plants is reported. Uranium - Aluminium and thorium canning are reported for the 300 area (reactor fuels fabrication). And stainless steel corrosion studies are reported for the 400 area (heavy water).

Calculations are presented for the estimated minimum critical mass of Pu that would be allowed in Hood No. 5 and the filter boat cleaning and testing hood of the Plutonium Finishing Plant. Hood No. 5 contains the overflow tank and two vacuum traps. Limits are given for several pile exposure rates. These limits do not allow the approach of personnel into Hood No. 5 when these vessels are full.

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The APPR-I is described and the various hazards are reviewed. Because of the reactor's location near the nation's Capitol, containment is of the utmost importance. The maximum energy release in any possible accident is 7.4 million Btu's which is completely contained within a 7/8 inch thick steel cylindrical shell with hemispherical ends. The vapor container is 60 ft high and 32 ft in diameter and is lined on the inside with 2 ft of reinforced concrete which provides missile protection and is part of the secondary shield. All possible nuclear excursions are reviewed and the energy from any of these is insignificant compared to the stored energy in the water. The maximum credible accident is caused hy the reactor running constantly at its maximum power of 10 Mw and through an extremely unlikely sequence of failures, causing the temperature of the water in the primary and secondary systeras to rise to saturation; whereupon a rupture occurs releasing the stored energy of 7.4 million Btu's into the vapor container. If the reactor core melts during the incident, a maximum of 10/sup 8/ curies of activity is released. While it appears impossible for a rupture of the vapor container to oecur except …

A plant designed for concentrating thorium by extraction from pitchblende residue by use of tributyl phosphate followed by hydrofluoric acid strip is described. The fluoride product is further purified by a solvent extraction flowsheet in hot laboratory equipment. An outline of the chemical technology used in this process is presented. (J.R.D.)

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An internally heated chlorinator using a bed of graphite as a resistor element in contact with molten salt was shown to be feasible. An extended run was completed in an electrolytic cell demonstrating the feasibility of continuous operation. Other studies are reported on chlorination of thorium oxycarbonate and physical metallurgy evaluations of the Th produced. (T.R.R.)

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