British nuclear weapons testing in Australia

• Nuclear weapons testing occurred from 1952 to 1963 at Maralinga, South Australia; Montebello Islands, Western Australia and Emu Field, South Australia.

• Following the clean-up of the area around Maralinga in South Australia where nuclear weapons testing was conducted, radiation dose assessments have shown that the area is suitable for access.

• There are still some precautionary restrictions on permanent occupancy within a boundary surrounding Taranaki, a former test-site at Maralinga.

• At Montebello some precautionary visitor restrictions still remain in place for small sections of the islands which were closest to the detonations.

From 1952 to 1963, the British government, with the permission of the Australian government, conducted a series of nuclear weapons development tests in Australia. The testing occurred at Maralinga, South Australia; Montebello Islands, Western Australia and Emu Field, South Australia. The tests included major trials described as detonation of nuclear devices and minor trials were investigating the performance of various components of a nuclear device.

Atomic detonations (major trials)

In total, 12 atomic detonations of nuclear devices occurred of varying sizes (yields) across Australia. This included:

• three at the Montebello Islands
• two at Emu fields
• seven at Maralinga

These atomic detonations, known as major trials, dispersed radioactive material into the environment. At Maralinga and Emu the nuclear devices were detonated from ground level and at higher altitudes. These nuclear explosions were not the major cause of contamination at Maralinga. As the nuclear device explodes, a large fireball is created. Everything inside of this fireball vaporizes and is carried upward creating a mushroom-shaped cloud. The material in the cloud cools into dust-like particles and drops back to the earth as radioactive fallout. This radioactive fallout is carried by the wind very long distances away from the site of the explosion.

At the Montebello Islands, the first nuclear device detonation was conducted in Operation Hurricane within the cargo hold of a Royal Navy ship, the HMS Plym. In the resulting atomic explosion, components of the ship became radioactive and were dispersed over the local area. These were mostly fragments of metal and have since been largely removed from the site.

The explosive yields (size of the explosion) of these tests were similar in size to the atomic weapons used on the Japanese cities of Hiroshima and Nagasaki.

Comparing Australian detonations

Nuclear detonations in Australia: 12
Duration: (1952-57)
Total yield: 181 kilotons

Nuclear atmospheric detonations globally: 520
Duration: 1945 - 1963
Total Yield: 545 000+ kilotons 

Nuclear detonations globally: 2100+
Duration: 1945 - present
Total yield: 600 000+ kilotons

Largest nuclear detonation: atmospheric test of Tsar Bomba by USSR in 1961
Total yield: 50 000+ kilotons

* For the G2 test, reported yields have been estimated to be from 56 to 98kT. It should be noted that the exposure assessment was based on the higher yield estimated (Crouch et al. 2009).

Minor trials

Another part of the testing program involved a large number of minor trials. This testing consisted of experiments aimed at investigating the performance of components and safety of the nuclear devices. 

At Emu Field, minor trials involved the testing and experimentation of various radioactive materials such as polonium as weapons components that generate neutrons, an essential process in nuclear weapon detonation. Due to the short half-life of the materials and the small number of tests, these experiments did not lead to any long-term radioactive contamination of the environment at Emu.

The main cause of contamination at Maralinga was the minor trials. The minor trials did not involve nuclear explosions. At Maralinga, the minor trials resulted in the burning and explosive dispersal of radioactive materials, some with very long half-lives, using conventional high explosives. This meant radioactive contamination occurred over smaller areas, but at higher levels when the radioactive materials settled on the ground surface.

Contamination

Although several radioactive contaminants were dispersed into the environment, plutonium presented the largest long-term health risk to potential occupants and users of local areas. At Maralinga it was dispersed into the surrounding area by the minor trials. At Montebello visitor restrictions still remain in place for small sections of the islands which were closest to the detonations.

Plutonium is a hazard to humans if inhaled, ingested, or absorbed through breaks in the skin. External exposure to plutonium does not pose a health risk, as the element emits alpha particles which do not pass through skin.

Maralinga clean-up

Nuclear testing at Maralinga concluded in 1963 and the site was closed in 1967. As part of the site closure, the British Government conducted a clean-up of the site known as ‘Operation Brumby’. The operation, overseen by the United Kingdom Ministry of Defence, consisted of debris removal and soil ploughing. These techniques were used with the objective of diluting and burying the contamination.

Due to concerns about the level of contamination remaining, a Royal Commission was held. In 1985 the McClelland Royal Commission delivered its report, finding that significant radiation hazards still existed at the Maralinga test sites, particularly in Taranaki. The Royal Commission recommended rehabilitating the test sites to a state where present activities or future land use did not present radiation hazards to people and the environment. In 1993, the Maralinga Rehabilitation Technical Advisory Committee (MARTAC) was established to oversee the rehabilitation of the Maralinga test site. MARTAC’s responsibilities included managing the remediation effort carried out from 1995 to 2000.

Following the successful rehabilitation, dose assessments have shown that most of the contaminated areas at Maralinga fall well within the clean-up standards applied for unrestricted land use. This meant that activities and land uses such as hunting, mining exploration, or construction could proceed without exposure to radiation hazards. There are still restrictions on permanent occupancy within a ‘restricted land-use’ (non-residential) boundary surrounding Taranaki, a former test-site at Maralinga. These restrictions are precautionary in nature and are in place as control measures designed to contain any remaining contamination at the site and to discourage accidental intrusion into the burial trenches.

In November 2009 the Australian and South Australian Governments and Maralinga Tjarutja signed the Maralinga Nuclear Test Site Handback Deed, which gave effect to the return of the test site and Maralinga Village to Maralinga traditional owners.

References

1. P. Crouch, F. Robotham, G. Williams and K. Wise (2009). Assessment of Radiation Doses to Australian Participants in British Nuclear Tests, Radiation Protection Dosimetry, Vol. 136, pp. 158-167.
2. Department of Education, Science and Training, Rehabilitation of Former Nuclear Test Sites at Emu and Maralinga (Australia), Reported by the Maralinga Rehabilitation Technical Advisory Committee (MARTAC), Commonwealth of Australia (2002).