The Nuclear Fuel Cycle

The generation of nuclear energy involves a succession of operations. These operations are : uranium mining, conversion and enrichment of the uranium to produce fuel for reactors, fission of uranium in reactors to liberate heat, the generation of electricity by steam turbines, reprocessing of spent fuel to isolate plutonium and 'unburned' uranium and storing the radioactive wastes. This sequence of operations is referred to as the nuclear fuel cycle.

The nuclear energy system is called a cycle because the plutonium and unused uranium isolated by reprocessing the wastes at the 'back end' of the cycle can be returned to the 'front end' as fuel.

Although the operations of the nuclear industry can be represented as a cycle, it's various operations are not carried out in one place but are scattered all over the worod. This means movement of radioactive cargoes along highways and sea lanes and even air routes.

Australia's only involvement is mining and refining of uranium at the 'front end' of the cycle and the operation of small nuclear research reactor facilities at Lucas Heights in southern Sydney by the Australian Nuclear Science and Technology Organisation (ANSTO - they are currently undertaking an EIS for a new, larger research reactor). All political parties (including the Liberal Party since 1994) have declared policies against the building of nuclear power reactors in Australia. However, ANSTO has worked with the aim of Australia storing our uranium customers' high-level radioactive wastes.

Uranium Mining

Miners are exposed to the hazards of ionising radiation emitted by radon and radioactive dust. As we learn more about ionising radiation it is found to be ever so much more dangerous than previously thought.

Mining sites become scarred landscapes.

Tailings Dams

After mining ceases, tailings dams become hills of fine sand-like solids. These retain 80 per cent of the radioactivity of the ore body. Thorium-230 in tailings decays into radium-226 which in turn decays into radon-222, a gas which spreads over the region.

Radioactive radium, dust and radon contaminate the air, land and waterways. Neighbourhoods suffer cancer and birth defects. The radioactive hazards of tailings at old uranium mining sites will persist for over 100,000 years.

Conversion to 'Hex'

Uranium hexafluoride (called 'hex') is used for enrichment because it is a gas at low temperatures. Radioactive gases are emitted during its production.

'Hex' is hazardous both as a chemical and for its radioactivity. An accident in transport could be catastrophic. Exposure to 'hex' can cause serious kidney damage.

Enrichment

Plant producing reactor grade uranium (3% uranium-235) can also produce the highly enriched weapons-grade uranium (over 90% uranium-235). A country with an enrichment plant has the means to produce nuclear weapons within a very short time.

Radioactive gases are emitted to the atmosphere.

Fuel Fabrication

Workers are exposed to radioactive dusts. The health hazards are greatly increased when 'mixed oxide fuel' of plutonium and uranium (MOX) is used in power reactors.

Reactor Operation

Every 12 months one-third of fuel rods in a reactor are replaced. The spent-fuel taken from the reactor is stored in cooling ponds at reactor sites until it loses much of its heat and radioactivity (initially equivalent to 5 million kgs of radium). The spent-fuel contains about 250 kg plutonium.

Radioactive water and gases are released routinely. There are many accidental releases. Accidents at Windscale and Three Mile Island caused health problems from iodine-131 in populations in downwind regions.

The accident at Chernobyl contaminated vast food-producing areas and affected the health of about four million people causing immune deficiencies ('Chernobyl AIDS') and cancer. It is now widely accepted there will be more 'Chernobyls'.

Reactors must be decommissioned. Demolition can cost as much as building a reactor. The radioactive remains must be stored and guarded for hundreds of years.

Reprocessing

Millions of litres of radioactive water pour daily into the sea from the world's two commercial plants at Sellafield in Britain and Cap la Hague in France. Krypton-85 and other gaseous wastes are released from these plants.

At Sellafield 500 kilograms of plutonium and 40 other radionuclides, have been released into the Irish Sea. Fish caught in the local waters are radioactive. Sellafield's plutonium is found in the far-away Arctic ice. People in the region have thousands of times more plutonium in their body than other people. Childhood cancers are six times higher than the national average.

Plutonium is uneconomic as a fuel. As a way of disposing of reactor waste reprocessing creates greater environmental problems than storing spent-fuel directly. The real incentive of several nations is undoubtedly to hold stocks of plutonium ready to use in nuclear weapons.

Transport of Radioactive Wastes

The operation of the nuclear fuel cycle is carried out in many facilities scattered around the world. This means that dangerous radioactive materials are being carried over land and sea in trucks and ships. Plutonium, recovered during processing, is taken back to countries which created the waste sometimes by aeroplane.

Such transport is highly regulated by the nuclear authorities but accidents will happen and people have been exposed to radioactivity after accidents.

Even if each accident added only little radioactivity to the global environment over the years the risk to human health will mount. A serious accident involving 'hex', spent-fuel or high-level waste would be catastrophic for the communities directly affected.

Depleted Uranium

Uranium depleted of its uranium-235, called 'tails' (uranium-238), is being stored. The nuclear industry hopes to use breeder reactors next century to convert its 'tails into plutonium.

Uranium-238 can be inserted into a power reactor where, bombarded by neutrons, it forms plutonium-239. This can be done between IAEA inspections.

Liquid Wastes

Liquid wastes are routinely released into rivers and coastal waters from reactors and other plants in the nuclear fuel cycle.

A reactor's cooling waters contain hazardous levels of tritium (radioactive hydrogen) so readily absorbed by body tissues. Tritium releases have been associated with childhood leukemia and birth defects.

Low-Level Waste

Bulky low-level radioactive rubbish ­ contaminated paper, plastics, gloves, clothing, tools, building materials ­ accumulate at all stages of the nuclear fuel cycle. It is dumped in shallow graves and covered with earth. Until banned by the London Dumping Convention, in 1975, this radioactive rubbish was dumped at sea.

Intermediate-level waste ­ glove boxes and other equipment contaminated with transuranic elements (e.g. plutonium and americium) and sludges ­ is buried at supervised sites in concrete lined trenches.

Radionuclides from existing land dumps have been found to leak into the surrounding soil and waterways.

High-Level Wastes

Reprocessing produces intensely radioactive liquid wastes. Most is stored in tanks awaiting evaporation and solidification into glass blocks.

Glass blocks holding the waste are supposed to be put into deep burial sites. However, since it was found that the heat of radioactive decay cracks the glass the blocks will now stay in cool stores for up to 100 years before burial.

Some countries have accepted that reprocessing is uneconomic. They have opted for a 'once-through' cycle. Spent-fuel is to be disposed of in canisters in a rock repository.

Deep Burial

Over many years the industry has failed to solve the waste problem and establish repositories for high-level waste. They are accumulating dangerously in temporary storages.

Information from the MAUM public education sheet on the Nuclear Fuel Cycle.
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