Mal Washer (Moore, Liberal Party) Share this | Hansard source

I compliment the member for Blaxland on an excellent speech on synroc new reactor technology. I hasten to add that his knowledge in this field is admirable. He knows a lot more about this than he does about changing tyres, which I discovered on the way to ANSTO where we had a good time looking around.

The Australian Nuclear Science and Technology Organisation Amendment Bill 2006 will amend the Australian Nuclear Science and Technology Organisation Act of 1987, enabling the Australian Nuclear Science and Technology Organisation to condition, manage and store radioactive material and waste other than that associated directly with its own activities. The Australian Nuclear Science and Technology Organisation, ANSTO, is Australia’s national nuclear research and development organisation and the centre of Australian nuclear expertise. This bill will enable it to utilise this expertise in the management of radioactive material and waste in the possession or under the control of any Commonwealth entity. It will also enable ANSTO to assist law enforcement or emergency response agencies in incidents involving radioactive material, helping to ensure public health and safety. This could be a terrorist incident or a criminal one, such as undeclared materials intercepted by the Australian Customs Service. The bill also clarifies ANSTO’s authority to deal with intermediate level waste returned from the overseas reprocessing of its spent nuclear fuel.

So what exactly are we talking about when we refer to radioactive materials and waste? Nuclear radiation was discovered in 1896 by Henri Becquerel. Nuclear radiation is emitted by certain types of atoms, known as isotopes, which contain more neutrons than protons in their nucleus. All atoms of a particular element have the same number of protons in their nucleus. This determines the atom’s identity as one element or another. For example, every atom of carbon has six protons. Protons and neutrons have about the same size and mass and together make up most of the mass of the atom. The number of neutrons in the nucleus may vary. Additional neutrons do not change the atom’s chemical properties; however, for some elements the extra neutrons make the nucleus unstable and it eventually undergoes spontaneous radioactive decay. As this decay produces nuclear radiation, these unstable elements are known as radioisotopes. For example, the radioisotope carbon-14 has six protons, like any other carbon, but it has eight neutrons—the number 14 referring to the mass number, which is the total number of protons and neutrons in the atom’s nucleus.

When a radioisotope decays, it not only releases radiation but also changes the number of protons in its nucleus and becomes a different element. The radioisotope keeps decaying into other radioactive elements until a stable isotope is produced and the decay series stops. For example, when uranium-238 decays, 14 different radioactive elements are produced before the series finally ends with stable lead-208. The average amount of time that it takes for the radioisotope to decay is referred to as the half-life. This is the time taken for half of the atoms in a sample to decay. This length of time can vary widely for different radioisotopes and it greatly affects their use and disposal. For example, it takes 4.5 billion years for an atom of uranium-238 to decay through all 14 isotopes into lead. However, more than 99.99 per cent of this time is taken up with waiting for the first decay to occur. The other steps in the series are much faster, some taking millions of years and most taking just days or minutes.

The radiation released from unstable atoms as they go through decay may be made up of alpha particles, beta particles and/or gamma rays. These forms of radiation have different levels of energy and need to be managed in different ways. Alpha radiation is made up of streams of particles consisting of two protons and two neutrons—essentially a helium atom without electrons. This radiation is highly charged and is referred to as ionising radiation, as it knocks electrons from atoms. This causes these atoms and surrounding molecules to become charged particles, or ions. Beta radiation also has an ionising effect, as it is made up of electrons being ejected from the nucleus. Gamma radiation is also an ionising radiation but is uncharged. It interacts with ions already present, rather than creating them, and causes changes in the materials it passes through. It is not made up of particles but is an electromagnetic energy wave, like light or X-rays. There are gamma rays from space that are passing through our bodies right now.

Elements that have these unstable atoms are naturally occurring and have been created by the formation of the earth and cosmic radiation. Every day we are exposed to the radiation given off by these elements, as they are in our soil, rocks, the air we breathe, the water we drink and the food we eat. They are also in our muscles and bones. Living and working in buildings built from bricks, mortar, concrete and tiles increases our exposure, as they all contain radioactive elements. We have learnt how to use radioactive elements to our benefit and utilise them in medicine, industry, agriculture and other scientific fields. One of the most common uses of radioactive material in the home is the smoke detector. Ionisation smoke detectors contain the radioactive element americium and are extremely sensitive to particles of smoke. The alpha radiation given off by the americium ionises the oxygen and nitrogen particles in the air. The positive and negative charged particles created from this enable an electrical current to flow between two plates. If there are smoke particles present in the air, this current is disrupted and the alarm goes off. The radiation levels are extremely small and it is predominately alpha radiation, which is unable to penetrate a sheet of paper or even a few centimetres of air.

Our homes also contain many products which have been sterilised by radiation, such as disposable nappies and first-aid products like bandages and cotton wool. In Australia around 550,000 people benefit from medical procedures involving radioactive materials every year. Two of the major tools used in nuclear medicine are radioisotopes, and energy and particle beams.

Radioisotopes can be used as tracers to diagnose medical problems or to treat certain illnesses. The radioisotope can be traced through the body by detecting the radiation it gives off. The tracers used in medicine give off gamma radiation as this is less biologically damaging than alpha or beta radiation. Gamma radiation is also able to pass through the body to be detected by the measuring instruments outside.

The imaging process known as positron emission tomography, or PET, uses radioisotopes for this purpose. When disease strikes, the biochemistry of your tissues and cells changes. In cancer, for example, cells begin to grow at a much faster rate, feeding on sugars like glucose. PET works by using a small amount of isotope chemically attached to glucose or other compounds. It travels through your body and collects in the organs targeted for examination. If an area in an organ is cancerous, the radiation being given off in this area will be stronger than in the surrounding tissue. A scanner records this and transforms the signal into pictures showing chemistry and function.

Many isotopes used in this process have short half-lives. Fluorine-18, which is commonly used, has a half-life of 110 minutes. Because of this, hospitals which have PET facilities need to be within one or two hours of a cyclotron which generates these isotopes.

Gamma radiation energy beams are also used in radiotherapy to destroy cancers located in places that cannot be accessed easily with surgery. In order to spare normal tissues, several angles of exposure are utilized such that the radiation beams overlap each other at the tumour site, providing a much larger absorbed dose there than in the surrounding healthy tissue.

Another form of radiotherapy cancer treatment that is much more specific at targeting cancer cells is the proton particle beam. Proton radiation therapy is also an ionising radiation like gamma radiation but is made up of proton particles. When they first enter the patient, the protons do no damage to the healthy tissue as they are moving at half the speed of light. As they penetrate tissue and slow down, an increasing dosage of ions is generated and the cells which have been targeted are killed. When the protons have slowed down to around half the speed, they absorb an electron to become a hydrogen atom and ultimately join up with another hydrogen atom and an oxygen atom to form water. This is carefully tuned to occur at the back side of the tumour.

The ionising effect of the radiation kills the cancerous cells. The ions damage molecules within the cells, particularly the genetic material, DNA. Damaging the DNA destroys specific cell functions, particularly the ability to divide and proliferate. Enzymes develop within the cells to attempt to rebuild the injured areas of DNA. However, if the damage is too extensive, the enzymes fail to adequately repair the injury. While both normal and cancerous cells go through this repair process, a cancer cell’s ability to repair injury is inferior. As a result, the cancerous cells sustain more permanent damage and die. This allows the selective destruction of cancerous cells growing amongst our good cells. Hadron beams, which are beams of atomic nuclei, can complement proton beam therapy for tumour treatment. We certainly need these facilities in this country. We do not have these facilities.

Radioactive tracers are not used just in the field of medicine; they are also used in many other situations where one wants to track a particular particle in a system. A range of environmental measuring processes detecting stream flows, sedimentation rates, water quality and soil and water salinity use radioactive tracers. For example, ANSTO has been investigating the long-term sustainability of irrigation practices in New South Wales. This is something the member for Blaxland and I witnessed when we went to the facility. Scientists have labelled trace amounts of water molecules with radioactive tritium. This enables them to track these molecules and understand the subterranean water flows between the Macquarie River and the bores. Scientists can then advise on where, when and how much water can be used sustainably. Radioactive materials used for environmental measurements have short half-lives and decay to background levels in a matter of days.

Radioactive waste in Australia is produced as a consequence of these beneficial uses of radioactivity. At present low- and intermediate-level radioactive waste is stored by Commonwealth, state and territory agencies at over 100 locations around Australia. Many individual waste producers currently have the responsibility of looking after their own radioactive waste. This bill will enable ANSTO to make its expertise and facilities available to assist these agencies. (Quorum formed) With the establishment of the Commonwealth radioactive waste management facility, it will be important for ANSTO’s capabilities to be available for conditioning and repackaging waste from agencies prior to transport to the facility.

This bill will enable efficient and responsible handling of radioactive waste, enabling Australians to continue utilising the benefits of radioactive materials in their lives. I commend the bill to the House.

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