Heat-flow studies using an instrumented fuel assembly inside the EWA reactor

Comprehensive studies of flow of heat through the EWA reactor core were done in 1972-73 using a fuel assembly equipped with some thermocouples situated in grooves cut in the fuel cladding in such a way that conditions of heat exchange were not disturbed. Steady state temperatures measured at the assembly circumference at several different reactor power levels with all pumps of the primary reactor cooling loop operational and at simulated failures of 1, 2, and of all 3 pumps helped to determine the reactor power levels at which overheated water started to boil. The project was quite pioneering at that time, similar in-core measurements were not yet done in any other research reactor. The measurements showed that power of the EWA reactor could be safely increased by 50% (from 8 up to 12 MW) without changing any coolant parameter.

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NCBJ Research Reactor Technology Division