Experiments in the controlled melting of irradiated fuel specimens, particularly of the APPR, STR, and MTR types, have confirmed that prolonged heating in air at temperatures in excess of the melting point results in the release of a large portion of the radioactivity. On the other hand, a moderate amount of heating in air or steam sufficient only to melt a specimen results mainly in the partial volatilization of rare gases, iodine, bromine, cesium, and rubidium. In the presence of air or water vapor, strontium and other fission products are not released. At trace concentration of fission products, slow melting of the APPR plate at 1525 C in air or steam effected the release of 50% of the rare gases, 33% of the iodine, 9% of the cesium, and traces of strontium. After 25% burn-up, the cesium value increased to about 60%. Aluminum alloy of the MTR type, also at trace concentration, upon melting at 700 C released up to 2% of the iodine, 10% of the rare gases, and negligible portions of other fission products. Zirconium alloy of the STR type after 15% burn-up, when melted at 1850 C, released up to 95% of the rare gases, 90% of …

A series of two-group calculations has been made on the Oracle for the purpose of obtaining critical-mass and flux distribution data for various ORR core configurations. The 3G3R code of Bate, Einstein, and Kinney was used, together with the RSP code developed by Nelson. This made it possible to obtain results for the three-dimensional case. The results, which are presented graphically, are intended to serve as a guide for the design of experiments until such time as actual measurements are available. The calculations were performed for the "clean cold" case, and it should be realized that the presence in the core of experiments and of fission products built up during operation will materially alter the flux patterns found. It is believed that the critical-mass data are accurate to within 10%. Within the fuel region it is believed that the thermal-flux patterns are the also accurate to this degree. Comparison of the results with MTR critical experiments, however, indicates that the thermal flux in the reflector in the vicinity of the fuel-reflector interface may have been underestimated by a factor of as much as 1.3. It should also be recalled that in a two-group calculation the "fast flux" is often a …

This report is presented in order to provide a satisfactory system of symbols and identifications for process-instrumentation equipment and to promote a uniformity of practice that will simplify and expedite instrumentation work. It is intended that the systems presented here should be capable of designating and identifying the multitude of instrumentation items which are used for control and operation of conventional processes, as well as for specialized work peculiar to ORNL. Instrument Society of America standards have been adhered to whenever practical.

For Co60 source at 15 meters, the air-scattered gamma dose rate predicted by theory is excerpted from ORNL-1575, pp. 167-203. This is compared with experimental measurements for the same source and comparable geometry reported by Convair in CVAC-170T. After applying an appropriate correction for ground scattering as estimated in Mart-55-16T (Convair), the two results are found to be in substantial agreement.

Chemical and engineering data were obtained for the feed digestion system and the extraction-scrub step of the Monex tributyl phosphate solvent-extraction process for recovering thorium and uranium from nitric acid-digested unclarified monasite sludge. Tests of the recommended conditions in a 2-in.-dia pulsed column demonstrated that thorium losses were approximately 1.2% and uranium losses, 1.5%. The flowsheet is workable but is not necessarily optimum.

The Aircraft Reactor Experiment (ARE)was successfully concluded in November of 1954, and a detailed report of the operation was published the following year. At that time it was thought that an extensive examination of the reactor and system components after disassembly was warranted. It was realized, of course, that the level of radioactivity of the components would necessitate extensive delays in the examinations. Since examination of a few critical ARE samples showed nothing unexpected, much of the planned hot-cell inspection was postponed and complete examination of all but a few specimens was indefinitely suspended. The few examinations that were completed are described in this report, along with a description of the disassembly of the ARE system. Diagrams of the fuel system, sodium system, and off-gas system are presented in Figs. 1, 2, and 3 for reference use in visualizing the disassembly process.