HRE-2 Homogeneous Reactor Experiment

Introduction. In 1950 the Oak Ridge National Laboratory undertook the task of designing, building, and operating a pilot-plant fluid-fuel reactor, the Homogeneous Reactor Experiment (HRE-1), shown in... 

The component development work at ORNL has been directed primarily toward equipment for mse in the Homogeneous Reactor Experiment (HRE-1) and the Homogeneous Reactor Test (lIRE-2). Although the HRE-2 has both a core and a blanket, most of the components in these two systems are identical and designed for use with solutions rather than suspensions. 

The homogeneous reactor experiment-2 (HRE-2) was tested as a power-breeder in the late 1950s. The core contained highly enriched uranyl sulfate in heavy water and the reflector contained a slurry of thorium oxide [1314-20-1J, Th02, in D2O. The reactor thus produced fissile uranium-233 by absorption of neutrons in thorium-232 [7440-29-1J, the essentially stable single isotope of thorium. Local deposits of uranium caused reactivity excursions and intense sources of heat that melted holes in the container (18), and the project was terrninated. 

As an alternative to using a solid fuel matrix, both core and blanket can be liquid. In the HRE-2 (homogeneous reactor experiment), USA, the core consisted of a sulfate solution in D2O, while the blanket was a suspension of Th02 in D2O. The project was terminated because of various technical difficulties. 

Construction of the reactor (Homogeneous Reactor Experiment No. 1) was started in September 1950, and completed in January 1952. After a period of nonnuclear testing with a natural-uranium fuel solution, HRE-1 reached criticality on April 15, 1952. Early in 1954 it was dismantled after successfully demonstrating the nuclear and chemical stability of a moderately high-power-density circulating-fuel reactor, fueled with a solution of enriched uranyl sulfate. 

During the period of construction and operation of HRE-1, conceptual design studies were completed for a boiling reactor experiment (BRE) operating at 150 kw of heat and a 58-Mw (heat) intermediate-scale homogeneous reactor (ISHR). Further work on these reactors was deferred late in 1953, however, when it became evident from HRE-1 and the associated development program that construction of a second homogeneous reactor experiment would be a more suitable course of action. 

Application of copper sulfate catalyst to the suppression of gas evolution during the operation of the Homogeneous Reactor Experiment was discussed by Visner and Haubenreich [41], Design calculations for use of copper catalysts in the HRE-2 and in other reactors have been reported [42], The use of internal recombination catalysts in homogeneous reactors is also discussed in Article 7-3.7. 

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