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What are some of the differences between the new reactor OPAL and HIFAR?

OPAL has a modern, open pool design, is fuelled by low-enriched uranium and is capable of generating 20 MW (megawatts) of thermal power, whereas HIFAR was a 1950s-style tank-type reactor fuelled by high-enriched uranium (although in its final years it used low-enriched uranium) which generated 10 MW of thermal power.  A key requirement for research reactors is the level of the neutron flux.  OPAL produces a neutron flux at least three times greater than the flux that was produced by HIFAR.

With respect to the production of radioisotopes for use in nuclear medicine, OPAL will initially be able to produce four times the quantity of the key medical radioisotope molybdenum-99 that was produced in HIFAR.

For research, the quality of the neutron beams being produced with OPAL is many thousands of times better, because the beams are more intense and substantially free of gamma radiation.  Furthermore, with OPAL some of the neutron beams are delivered at cold (approximately -250°C) temperatures.  These beams were not available at HIFAR, but are the type of beams used in state of the art research at the leading international nuclear research centres, particularly for soft matter science and structural biology.