Amid fears that Japan’s Fukushima Power Plant could suffer a meltdown [1], and the fact that the nuclear crisis is worsening [2], some people are probably wondering if a similar nuclear crisis could happen here in Australia. Well Australia only has one nuclear plant, and that is the ANSTO run OPAL reactor at Lucas Heights south of Sydney. The reactors at Fukushima are very different to the OPAL reactor and there is really no cause for concern in Australia. The differences between these reactors are explained below.
Fukushima Power Plant Reactors
The plants at Fukushima are Boiling Water Reactors (BWR) [3]. In a BWR the nuclear fuel heats water, the water boils and creates steam, the steam then drives turbines that create the electricity, and the steam is then cooled and condensed back to water, and the cycle is repeated. The reactor operates at about 285 °C. The nuclear fuel is uranium oxide which is a ceramic with a very high melting point of about 2800 °C [3].
The core of the reactor is contained in a pressure vessel. The pressure vessel is a thick steel vessel that operates at a pressure of about 7 MPa (~1000 psi), and is designed to withstand the high pressures that may occur during an accident [3]. The entire primary loop of the nuclear reactor – the pressure vessel, pipes, and pumps that contain the coolant (water) – are housed in the containment structure. The containment structure is a hermetically (air tight) sealed, very thick structure made of steel and concrete. [3].
This diagram illustrates the reactor operation and the meltdown process [4].
The ANSTO OPAL Reactor
The OPAL reactor is a nuclear research reactor. It is primarily used for neutron beam research as well as irradiation for radioisotope production [5]. The reactor plays an important role in nuclear medicine, creating radiopharmaceuticals to help doctors diagnose and treat diseases such as cancer, heart disease, neurological disorders and other conditions [6]. The reactor also provides for neutron-activation analysis of materials, and silicon ingot doping for the semiconductor industry [5].
This PDF file shows the OPAL reactor [7]. OPAL uses low-enriched uranium fuel with around 20 percent uranium-235. The primary OPAL cooling system operates at approximately 37°C. The reactor is housed in a steel reinforced building designed to withstand external events, including a one in ten thousand year seismic event, or impact from a light aircraft [8].
Concluding Statements
The OPAL reactor produces 20 MW [8] at full power while each of the Fukushima Power Plants produces 800 MW [9], or 40 times as much power. Quite simply put, there is no chance of the OPAL reactor melting down.
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