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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 is the Phase 2 (adherence) assessment plan for the Building 7503 Molten Salt Reactor Experiment (MSRE) Facility standards/requirements identification document (S/RID). This document outlines the activities to be conducted from FY 1996 through FY 1998 to ensure that the standards and requirements identified in the MSRE S/RID are being implemented properly. This plan is required in accordance with the Department of Energy Implementation Plan for Defense Nuclear Facilities Safety Board Recommendation 90-2, November 9, 1994, Attachment 1A. This plan addresses the major aspects of the adherence assessment and will be consistent with Energy Systems procedure QA-2. 7 ''Surveillances.''

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[en] This paper provides a review of certain conceptual design features for the Molten Salt Reactor (MSR) and the relevant experience gained from the Molten Salt Reactor Experiment (MSRE) that operated in Oak Ridge National Laboratory (ORNL). The purpose of the review is to explore the challenges that may arise in applying the current international standard of Ref. [1] that provides guidance on the Safety Analysis Report (SAR), to the design features and postulated accidents of a newly built MSR. The review found that while the current lARA standard is adequate to capture the safety issues arising from the MSR design, a number of features peculiar to the MSR need to be captured by the SAR and covered by the lARA standard within the routine update process of the standard. (author)

[en] At the Shanghai Institute of Applied Physics, China, there are plans to build an experimental molten- salt reactor whose design makes meltdown far less likely. A 'virtual' reactor displays an intricate system of pipes carrying the cooling fluid that makes this system special, and then carries heat to drive the turbine and make electricity. Alvin Weinberg was the pioneering nuclear physicist at Oak Ridge National Laboratory, who developed a prototype molten-salt reactor from 1965-1969, before it fell out of favour.

[en] During FY 1995 considerable progress was made toward gaining a better understanding of the chemistry and transport processes that continue to govern the behavior of the Molten Salt Reactor Experiment (MSRE). As measurements in the MSRE proceed, laboratory studies continue, and better analyses are available, our understanding of the state of the MSRE and the best path toward remediation improves. Because of the immediate concern about the deposit in the auxiliary charcoal bed (ACB), laboratory studies in the past year focused on carbon-fluorine chemistry. Secondary efforts were directed toward investigation of gas generation from MSRE salts by both radiolytic and nonradiolytic pathways. In addition to the laboratory studies, field measurements at the MSRE provided the basis for estimating the inventory of uranium and fluorine in the ACB. Analysis of both temperature and radiation measurements provided independent and consistent estimates of about 2.6 kg of uranium deposited in the top of the ACB. Further analysis efforts included a refinement in the estimates of the fuel- salt source term, the deposited decay energy, and the projected rate of radiolytic gas generation. This report also provides the background material necessary to explain new developments and to review areas of particular interest. The detailed history of the MSRE is extensively documented and is cited where appropriate. This work is also intended to update and complement the more recent MSRE assessment reports

[en] The characteristics and the problems of molten salt reactor concept are described on the basis of experience with the construction of the MSRE experimental reactor and of the MSBR breeder reactor. The molten salt reactors used as thermal converters are described in detail as is their technology. Graphs are listed of the relations between the conversion ratio and thorium concentration, of the time course of the heavy element isotopes in the converter core, and of the fuel cycle costs of the converter. The molten salt reactors as thermal converters have the advantage of using plutonium from other reactors without requiring fuel element production. Reactors of this type also have specific safety features. Special problems are posed by the spreading of fission products into the entire primary coolant circuit, by increased tritium production and by tritium diffusion capacity. (Oy)