HiFAR a description of the reactor
HiFAR is an acronym for High Flux Australian Reactor.
HiFAR was built in the late 1950's as a 'Materials Testing Reactor' (MTR). It's purpose was for evaluating materials destined for use in what was to have been Australia's Power Reactor Programme, under the auspices of the Australian Atomic Energy Commission. With the scrapping of the nuclear power programme in the 1970's, the reactor became a dedicated research reactor providing:
- neutron scattering facilities for scientific research,
- production of medical and industrial radio-isotopes, and
- neutron transmutation doping of silicon for semiconductor manufacturers world-wide (NTD silicon).
The design was that of a Thermal, Heavy Water Moderated core, based on a Brittish reactor named DIDO, developed and operated by the UKAEA at Harwell in England. It incorporated a spacious core providing numerous irradiation facilities with neutron fluxes around one hundred times those found in power reactors. So, for a material being tested, one week's exposure in HiFAR was equivalent to one hundred weeks exposure in a typical power reactor. This meant that materials could be quickly evaluated and ranked for their suitability for a reactor environment.
The reactor produced ten Mega Watts of heat which was removed via three shell and tube heat exhangers (located in a plant room under the reactor) and dissipated to atmosphere via six cooling towers.
Return to Top
The Animated Vertical Section with Control Room.
The image above shows a vertical section of HiFAR.
Essentially, the reactor vessel (outlined in red) was a cylindrical aluminium tank about two metres in diameter and two metres deep with a dished bottom. Containing the core and some six tonnes of heavy water, it was surrounded by graphite blocks (except at the top) and the whole encased in concrete to provide adequate radiation shielding for operations personnel.
The structure was mounted on columns above a plant room which contained pumps, heat exchangers and storage vessels. The plant room was heavily shielded with dense concrete walls, and was inaccessible whilst the reactor was running.
Towards the bottom of the reactor tank was a horizontal plate which divided the tank into two (unequal) chambers. It provided location points for the 25 fuel elements, which seated on nozzles penetrating it. The lower chamber formed a 'plenum' where cooled water returning from the heat exchangers pooled before being directed via the nozzles up through the fuel elements and into the reactor tank.
From the reactor tank, the water was drawn down pipes via pumps in the plant room. The pumps then pushed the water back up through the heat exchangers where it was cooled before flowing up through the fuel again. The total heavy water flow rate was typically 395 kg/sec for a temperature change of 6 degrees C across the core. This information was used to calculate the thermal power at which the reactor was running. (With the heat capacity of heavy water at around 4.2 kJ/kg degree C at the operational temperature of 50 degrees C, the thermal power equates to 10MW). The heat picked up by the heavy water on its journey up through the fuel, was transferred in the heat exchangers. The resulting temperature drop for the heavy water between the heat exchanger inlet and outlet was monitored for each exchanger. It was this temperature difference which was actually used in the thermal power calculation.
Return to Top
The animation:
Originally composed from an excellent illustration by an artist unkown, which leant itself to animating in Autodesk's Animator Studio (in the .AVI format). The Control Room is an addition not present in the original illustration, compiled from drawings done in Autodesk's AutoSketch for a manual I wrote and illustrated on the 'HiFAR Control Room Instrumentation' in 1995. It provides an accurate representation of the Control Room and the main instruments by which the reactor was 'driven'.
The animation was developed initially for training new Reactor Operators, but soon found wide-spread use in presentations to tour groups. If a picture is worth a thousand words, a moving picture is worth a thousand times that in getting a message across and in providing numerous visual cues for presenters.
It was converted to the .GIF format for portability using Jasc's Animation Shop 3.
Return to Top
