This form of experiment was dangerous, as the British acknowledged in their secret correspondence. AWRE safety co-ordinator Roy Pilgrim noted in a memorandum ‘the potential catastrophic nature of a mistake’ and urged ‘rigid adherence to the planned procedure’. The tests were not intended to produce nuclear reactions, but, in the event, as secretly predicted by the British, fission and fusion reactions did occur. Indeed, Pilgrim discussed fission openly with Ernest Titterton in a letter of October 1962, saying, ‘Whereas for previous Vixen B firings the experiments were so designed that fission products could not be present in quantities sufficient to add a radiotoxic effect… we are now seeking greater flexibility in the design of the experiments and to achieve this we need the freedom to plan in such a way that fission products may be generated’.
While the Vixen B test series used most of the plutonium-239 that contaminated Maralinga, various isotopes of plutonium were used extensively in other minor trials too. In one Tims trial, half a kilogram of weapons-grade plutonium was fired into a pad filled with salt, and six drums containing the contaminated salt were then buried at the Maralinga airport cemetery. This plutonium was mostly plutonium-239, along with some shorter lived isotopes – plutonium-240 and a tiny amount of plutonium-241. The plutonium from this test became the centre of a media controversy in 1978 when a secret Cabinet submission revealing the burial site was leaked to journalist Brian Toohey (see chapter 10). It was repatriated to Britain in 1979, the only loose plutonium from Maralinga to be recovered.
These high explosive tests ceased in 1963 when both Britain and Australia became signatories to the United Nations Partial Test Ban Treaty that outlawed atmospheric testing. The official name for the partial test ban treaty was Treaty Banning Nuclear Weapons Tests in the Atmosphere, in Outer Space and Under Water. It was signed in Moscow on 5 August 1963. An earlier moratorium on nuclear weapons testing, from 1958 to 1961, may have been knowingly subverted by the British test authorities in the case of the Vixen B tests, largely through the use of innocuous names (‘minor trials’, ‘assessment tests’), and without telling the Australian Government exactly what the tests involved. John Moroney wrote later:
Both [the UK and US] believed that these [one-point] studies were not nuclear weapons tests within the terms of the moratorium, but they were anxious not to be seen to be infringing the terms in any way. Accordingly, they performed the tests on reduced assemblies of the fission triggers to ensure that any nuclear yield was small, and conducted them under tight security, away from prying eyes.
As a direct result of the Vixen B tests, the feather beds, and lots of other equipment and buildings in the area, became impregnated with the most dangerous plutonium isotope, plutonium-239. The explosions created a kind of ‘dirty bomb’, releasing significant quantities of radioactive material into the atmosphere and subsequently onto the ground. In a submission to the Royal Commission, the ARL (now ARPANSA) ‘estimated that there were between 25 000 and 50 000 plutonium-contaminated fragments in the Taranaki area, although the number might need to be doubled if missed and buried fragments were included… The finding of this large number of plutonium-contaminated fragments was a surprise and changed the whole concept of hazard assessment of the plutonium-contaminated areas’. Over time, this calculation was revised to three million fragments. Staging the Vixen B trials cost Australia a lot of money – the cost for the first series alone was over £25 000 in labour, materials, plant hire and other expenses. It reaped three million loose fragments of plutonium.
Small particles of plutonium can be picked up readily in dust and can swirl around the landscape. Anyone in the vicinity might breathe it in. It is an insoluble particle that, if inhaled, lodges in the lungs, where it can stay throughout a person’s lifetime and irradiate its surroundings, possibly causing lung cancer. The risk is precisely proportional to the dose. If a person breathes in enough plutonium-239 to receive a dose of 1 millisievert (a unit of biological absorption of ionising radiation) the risk that he or she will get lung cancer is about one in 20 000. If a person ingests or inhales enough to receive a dose of 100 millisieverts then the risk is one in 200.
Leaving such a substance lying around on the ground was reckless. The widely dispersed Vixen B plutonium was not enough to kill people immediately through radiation sickness, but it could cause cancer over longer time frames. Given the ‘dusty lifestyle’ of the Indigenous population in the area, this was an unacceptable risk according to accepted international guidelines on the use of radioactive substances. While the AWRE maintained it followed the protocols laid down by the International Commission on Radiological Protection at the time of Vixen B, the plutonium contamination around Taranaki shows these assurances to be unfounded. The commission protocols relevant to the British tests were established in 1950 and updated several times during the test program, most notably in 1958. By the time of Vixen B these protocols had established that there was no threshold above which exposure became dangerous. Any exposure was dangerous.
Another risk was visitors coming to the site and picking up ‘souvenirs’, also unacceptable under the guidelines. To this day, no-one knows if such mantelpiece ornaments are out there – for several years during the 1970s the test range was not patrolled, and anyone visiting the area could have picked up a lump of plutonium-soaked rock or metal. The Commonwealth Police provided security services at the Maralinga site throughout the test program and remained there until 1 March 1974. In December 1976, when stories started appearing in the South Australian media about the Maralinga aftermath, the Australian Federal Police resumed surveillance. In between, only two civilian caretakers were on site.
In 1979, as the Maralinga story was breaking in the national media, South Australian scientists found that 19 rabbits around the Taranaki site had taken up a variety of radioisotopes in their fur, including plutonium-239, and this was cause for some consternation. In their report, quoted by Australian journalist Robert Milliken, a prominent chronicler of the British nuclear tests, they noted, ‘It is possible for rabbits, that are notorious for their ability to excavate burrows in almost any material, to gain access to the [Taranaki test debris burial] pits by simply burrowing under the 6 inch concrete slabs… As we are discussing products that have a half life of 24 000 years, it would seem almost a statistical certainty that in some time in the future the rabbits may have access to a pit’. The pits were dug into limestone, which formed the walls of the pits, and capped with concrete.
After the well-controlled media coverage up to the mid-1950s, from 1957 onwards journalists stopped writing stories about the British atomic tests. Once Howard Beale had gone to Washington and William Penney was engaged in Operation Grapple in the Pacific and, later, with the UK Atomic Energy Authority, the ongoing activities at Maralinga were not reported. However, both the British and the Australian authorities knew the Vixen B trials might attract media interest and planned for it. A sequence of correspondence in the second half of 1960 disclosed some of the official thoughts shared between the respective governments.
On 27 September 1960, Maurice Timbs, assistant secretary in the Prime Minister’s Department (and from 1964 to 1973 an executive member of the Australian Atomic Energy Commission), sent Menzies a statement drafted by the British, to be used ‘in the event of any public disclosure of the existence of these experiments [Vixen B]… The intention is that it will be held in readiness and released only if there is a public disclosure that these experiments are being carried out’.