At HAPO the protection of employees from nuclear radiations has paralleled or preceded the emphasis on atomic products production. The production of atomic products on the scale for which HAPO was designed presented voluminous problems in employee education, radiation detection, shielding, and indeed, fundamental research to determine working limits for the various types of radiation exposure which would necessarily be encountered, and to determine working limits for the deposition of radioactive isotopes and mixtures of isotopes in the human body. Since the time radioactive materials first arrived at HAPO and the start-up of the first HAPO reactor on February 23, 1944, there has been a fundamental philosophy that all employee exposure to nuclear radiations should be maintained at a minimum, as opposed to just some level of exposure below the accepted permissible limit. It was with this philosophy in mind that the many achievements and advances in the science of radiation protection at HAPO have been forthcoming. These advances in radiation protection ar discussed in this report.

None

None

A design study is presented for a sodium cooled, graphite moderated power reactor utilizing low enrichment uranium fuel. The design is characterized by dependence on existing technology and the use of standard, or nearly standard, components. The reactor has a nominal rating of 167 thermal megawatts, and a plant comprising three such reactors for a total output of 500 thermal megawatts is described. Sodium in a secondary, non-radioactive, circulation system carries the heat to a steam generator at 910 deg F and is returned at 420 deg F. Steam conditions at the turbine throttle are 600 psig and 825 deg F. Cost of the complete reactor power plant, consisting of the three reactors and one 150- megawatt turbogenerator, is estimated to be approximately ,165,000. (auth)