OPAL Reactor reflector vessel, designed by INVAP for the Australian Nuclear Science and Technology Agency (ANSTO). is a cylindrical tank of heavy water sitting at the base of the pool of lighter water containing the core. Manufactured in our facilities located at San Carlos de Bariloche, it is made of of zirconium alloy, 2.6 m in diameter and 1.2 m high. This vessel is vital in operating the reactor, as the heavy water reflects high energy neutrons released back into the core, maintaining the nuclear reaction.
The majority of neutrons enter this vessel at high energies. As they pass through the heavy water they lose this energy and are eventually reflected back into the core. Meanwhile, some neutrons escape and are absorbed by irradiation targets located in the reflector vessel, so not all the neutrons find their way back to the core. Some neutrons also find their way into neutron guides where they are channelled through mirrored guides to various research instruments.