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[en] Progress is reported on the development of processes for the isolation of protactinium and for the removal of fission products from molten-salt breeder reactors. The metal transfer experiment MTE-3 (for removing rare earths from MSRE fuel salt) was completed and the equipment used in that experiment was examined. The examination showed that no serious corrosion had occurred on the internal surfaces of the vessels, but that serious air oxidation occurred on the external surfaces of the vessels. Analyses of the bismuth phases indicated that the surfaces in contact with the salts were enriched in thorium and iron. Mass transfer coefficients in the mechanically agitated nondispersing contactors were measured in the Salt/Bismuth Flow-through Facility. The measured mass transfer coefficients are about 30 to 40 percent of those predicted by the preferred literature correlation, but were not as low as those seen in some of the runs in MTE-3. Additional studies using water--mercury systems to simulate molten salt-bismuth systems indicated that the model used to interpret results from previous measurements in the water--mercury system has significant deficiencies. Autoresistance heating studies were continued to develop a means of internal heat generation for frozen-wall fluorinators. Equipment was built to test a design of a side arm for the heating electrode. Results of experiments with this equipment indicate that for proper operation the wall temperature must be held much lower than that for which the equipment was designed. Studies with an electrical analog of the equipment indicate that no regions of abnormally high current density exist in the side arm. (JGB)
[en] This document outlines the program planned for the MSRE in fiscal years 1968 and 1969. It includes a bar diagram of the program, a critical-path type diagram of the operations, and a brief description of each task. In addition to the work at the reactor site, the outline also covers activities elsewhere at ORNL and by the AEC that directly affect the reactor schedule. The amount of detail and the accuracy with which we can estimate times varies considerably among the different items on the schedule. Some items, such as annual checkouts and core sample replacement, have been done before and our time estimates do not include any contingency, In the case of such tasks as planning, reviewing, and preparing for experiments or operations, we have set target dates that appear reasonable and we fully expect to meet these. Processing the salt is a different matter. If there are no unforeseen difficulties we should finish easily in the time shown, but the operation is in part a shakedown, so delays would not be too surprising, The time for modifying the system and adding fluoroborate is, of course, uncertain because the requirements are not yet known. As the requirements develop in more detail the estimate will be updated, but we do not foresee any major dislocation in the schedule, The scheduled time for preparation of enriching salt is becoming tight because of delays in facility construction. Should there be further delays in this key item, the entire schedule would have to be reconsidered.
[en] . In the last years, great investments have been realised in the technological renovation of equipment of existing nuclear power stations. Profitable investments, oriented to secure the result of an increase of electric power, generated through the improvement in the yield of the power station. The maintenance companies have to adapt their personnel and resources for this one type of modifying maintenance. One of these improvements has been the substitution of the MSR'S, equipment of the main steam located in the building of the Turbine. This article tries to reflect the challenge that supposes the substitution of equipment of great dimensions and weight with the singularity of being realised for a nuclear power plant. (Author). 3 Refs.
[en] Research and development activities dealing with the chemical problems related to design and ultimate operation of molten-salt reactor systems are described. An experimental test stand was constructed to expose metallurgical test specimens to Te2 vapor at defined temperatures and deposition rates. To better define the chemistry of fluoroborate coolant, several aspects are being investigated. The behavior of hydroxy and oxy compounds in molten NaBF4 is being investigated to define reactions and compounds that may be involved in corrosion and/or could be involved in methods for trapping tritium. Two corrosion products of Hastelloy N, Na3CrF6 and Na5Cr3F14, were identified from fluoroborate systems. The evaluation of fluoroborate and alternate coolants continued. Research on the behavior of hydrogen and its isotopes is summarized. The solubilities of hydrogen, deuterium, and helium in Li2BeF4 are very low. The sorption of tritium on graphite was found to be significant (a few milligrams of tritium per kilogram of graphite), possibly providing a means of sequestering a portion of the tritium produced. Development of analytical methods continued with emphasis on voltammetric and spectrophotometric techniques for the in-line analysis of corrosion products such as Fe2+ and Cr3+ and the determination of the U3+/U4+ ratio in MSBR fuel salt. Similar studies were conducted with the NaBF4--NaF coolant salt. Information developed during the previous operation of the CSTF has been assessed and used to formulate plans for evaluation of in-line analytical methods in future CSTF operations. Electroanalytical and spectrophotometric research suggests that an electroactive protonic species is present in molten NaBF4--NaF, and that this species rapidly equilibrates with a volatile proton-containing species. Data obtained from the CSTF indicated that tritium was concentrated in the volatile species. (JGB)