An evaluation of the relative health hazards of radioisotopes produced in nuclear reactors is reported. The most important hazards were indicated to be I131, the Sr90 - Y90 chain, the Ce144 -Pr144 chain, Sr 89, the Ba140-La40 chain, Y91, the Zr95-Nb95 chain, Pr143, La140 , and Pa233. The most critical body organs affected by air-borne contamination are the thyroid gland, the bone marrow, the lungs, and the gastrointestinal tract. Where possible, continuous daily removal of gaseous and solid fission products from the reactor environment can be shown to permit very significant reductions in the total hazards. Homogeneous reactors, such as the Thermal Breeder Reactor and the Homogeneous Plutonium Producer Reactor, specifically studied in this report, are designed with daily removal cycles and may be considered potentially safer than heterogeneous reactors.

From July through December, a total of 1750 hr of computer time was used by programmers in "debugging" and in running problems. With the acquisition of a second operator, the evening shift was initiated. A night-shift operator is presently being trained, and third-shifts operations will probably begin after completion of the magnetic-tape memory. / Engineering time is regularly scheduled for 4 hr each morning and 1/2 hr late in the afternoon. An electronic technician is on duty during evening-shift operations. / Installations of the magnetic-tape memory units is complete, and the units are expected to go into operation in the near future. Work is continuing on the new input-output system.

Progress report of the Oak Ridge National Laboratory Metallurgy Division providing updates on various projects, experiments, and other work. This report includes a summary of scholarly output and summaries of general corrosion, dynamic corrosion, mechanical properties, nondestructive testing, welding and brazing, fabrication, physical chemistry of corrosion, HRP metallurgy, the package power reactor program, APPR absorber, metallurgical materials and processing, metallography, ceramics, fundamental physico-metallurgical research.