Radioactive waste repository & store for Australia

(October 2007)

• Australia has a relatively small amount of low-level radioactive waste and rather less volume of intermediate-level waste (ILW). 
• A national repository for both categories of the Commonwealth's wastes is to be sited in the Northern Territory. 

While Australia has no nuclear power producing electricity, it does have well-developed usage of radioisotopes in medicine, research and industry. Many of these isotopes are produced in the research reactor at Lucas Heights, near Sydney, then used at hospitals, industrial sites and laboratories around the country.

Each year Australia produces about 45 cubic metres of radioactive wastes arising from these uses and from the manufacture of the isotopes - about 40 m³ low-level wastes (LLW) and 5 m³ intermediate-level wastes (ILW). These wastes are now stored at over a hundred sites around Australia. This is not considered a suitable long-term strategy.

Since the late 1970s there was an evolving process of site selection for a national radioactive waste repository for LLW and short-lived ILW. There was also consideration of the need to locate a secure storage facility for long-lived intermediate-level wastes including those which will be returned to Australia following the reprocessing of used fuel from Lucas Heights.

International practice

In other countries vastly more such waste is produced. Around the world, nuclear power generation produces over 150,000 cubic metres of low and intermediate-level wastes each year, and the extensive use of radioisotopes in medicine and industry would add to this. The UK and France each produce about 25,000 cubic metres of LLW annually.

LLW and short-lived ILW are disposed of in various ways, mostly in shallow burial. They are often incinerated or compacted first, to reduce their volume. Near-surface disposal of such wastes has been going on in about 70 facilities in several countries for over 35 years. A further 30 repositories are expected to open in the next few years.

Classification of radioactive wastes

There are several systems of nomenclature in use, but the following is generally accepted:

• Exempt waste - excluded from regulatory control because radiological hazards are negligible.
  
  
• Low-level waste (LLW) - contains enough radioactive material to require action for the protection of people, but not so much that it requires shielding in handling or storage.
  
  
• Intermediate-level waste (ILW) - requires shielding. If it has more than 4000 Bq/g of long-lived (over 30 year half-life) alpha emitters it is categorised as "long-lived" and requires more sophisticated handling and disposal.
  
  
• High-level waste (HLW) - sufficiently radioactive to require both shielding and cooling,
  generates >2 kW/m³ of heat and has a high level of long-lived alpha-emitting isotopes.

In Commonwealth government documents, low-level wastes are 'category A', short-lived ILW are 'category B' if amenable to embedding in concrete prior to disposal, or 'category C' if bulk material. Both require at least 5 metres of cover. Long-lived ILW are 'category S'.

Repositories are often located in populated areas and farming areas. France's main repository (for 1 million cubic metres), the Centre de l'Aube, is in the Champagne district, a former one is among Normandy farms, and the Drigg site is in UK in a scenic part of Cumbria, albeit not far from the Sellafield industrial complex.

Long-lived intermediate-level waste requires a higher degree of isolation from the biosphere and it is put into engineered geological repositories, or held in surface storage pending the development of such repositories.

High-level wastes (HLW), typically the used fuel from power reactors or the wastes left over from reprocessing this used fuel, contain most of the radioactivity from the nuclear fuel cycle. They generate heat due to the high radioactivity and require cooling as well as shielding. (Australia does not have any high-level waste. Its spent fuel from the research reactor - if waste, would be defined as "intermediate-level", and the waste which results from reprocessing it abroad will be returned as long-lived ILW for disposal or storage.)

* spent fuel from the HIFAR research reactor contains relatively high enriched uranium and requires reprocessing because of the degradability of the aluminium cladding of the fuel rod.

Australian plans

Any radioactive wastes which require it will be stabilised and solidified. Only those wastes in solid, stable form and devoid of corrosive or reactive materials will be accepted at the repository or store.

Other toxic wastes in Australia are either sent to licensed disposal sites or held in storage. Many of these such as mercury compounds, PCBs, organochlorines and hexachlorobenzene are extremely hazardous, many are liquids. Radioactive wastes are treated much more conservatively than other toxic wastes in relation to risks to people and the environment. Most of these other toxic wastes do not break down naturally in a way which corresponds to the progressive decay of radioactivity.

In countries with nuclear power, civil radioactive wastes comprise about 1% of overall toxic wastes. In Australia that proportion is very much less.

Low-level and short-lived intermediate level wastes will be disposed of in a shallow, engineered repository designed to ensure that radioactive material is contained and allowed to decay safely to background levels. Dry conditions will allow a simpler structure than some overseas repositories. The material will be buried in drums or contained in concrete. The repository will have a secure multi-layer cover at least 5 metres thick, so that it does not add to local background radiation levels at the site.

Australia has about 3700 cubic metres of low-level waste awaiting proper disposal, though annual arisings are small (the 40 cubic metres would be three truckloads). Over half of the present material is lightly-contaminated soil from CSIRO mineral processing research over 30 years ago (and could conceivably be reclassified, since it is no more radioactive than many natural rocks and sands).

Long-lived intermediate-level (category S) wastes will be stored above ground in an engineered facility designed to hold them secure for an extended period and to shield their radiation until a geological repository is eventually justified and established, or alternative arrangements made.

There is about 500 cubic metres of category S waste at various locations awaiting disposal, and future annual arisings will be about 5 cubic metres from all sources including states & territories, Commonwealth agencies and from radiopharmaceutical production, plus the returned material from reprocessing spent ANSTO research reactor fuel in Europe. This will be conditioned by vitrification or embedding in cement, and some 26 cubic metres of it is expected by about 2020.

In May 2003 a final site for the national repository near Woomera in South Australia was decided. The disposal area of the repository would be about 100 metres square, with long trenches up to 20 metres deep. It would be set in a 2.25 square kilometre buffer zone.

For the ILW store, the secure building with concrete vaults for the category S wastes would occupy a similar area.

But in mid 2004, bowing to state-level political implications, the Australian government abandoned these plans and told the states each to set up their own, to international standards. This failure in cooperation appeared to conclude twelve years of thorough bipartisan progress to locate and licence a single national facility. "All states and territories accepted the need for the safe and secure disposal, in one place, of low-level waste. But no-one wants it in their backyard." The Commonwealth government, owner of most existing low-level waste (totalling about 3700 cubic metres), started to look for a new site on commonwealth land to take only its wastes.

In July 2005 the government announced that a new Commonwealth Radioactive Waste Management Facility would be located at one of three sites in the Northern Territory, selection to be based on "field assessment", followed by environmental assessment and licensing. In the light of "the failure of the states and territories to cooperate with the Australian government in finding a national solution for the safe and secure disposal of low-level radioactive waste" and their making a political football out of it lin 2004, they will need to make their own arrangements elsewhere.

In May 2007 the Northern Land Council, an elected Aboriginal body in the Northern Territory, with the Ngapa clan who are the traditional owners, nominated the Muckaty pastoral holding as a potential site for the national radioactive waste facility. If the site is suitable the traditional owners will sign over 1.5 square kilometres for a long lease and receive A$ 12 million in benefits. In September 2007 the government accepted this nomination and Muckaty will be assessed along with Harts Range, Mount Everard and Fishers Ridge as potential sites for a low-level waste repository and an intermediate-level waste store, to open in 2011.

Once a preferred site is selected, a 2-year environmental assessment process will begin, in conjunction with the site licensing process.

Transport to any site will be regulated according to the relevant Code of Practice, but the low-level wastes will require little in the way of special provisions. The long-lived intermediate-level wastes will be very securely packaged. Low-level and short-lived intermediate level materials are transported in Australia every day and are considered less hazardous than flammable and toxic liquids such as petrol.

Sources:
Australian government, 1998, Information kit Our Radioactive Waste,
Australian government, June 1999, Report on public comment, phase 3 site selection study,
DISR, July 2001, Safe storage of radioactive waste - the national store project, www.radioactivewaste.gov.au
IAEA, Managing radioactive waste,
OECD NEA 1996, Radioactive waste management in perspective.