It is September 1960, and the first Vixen B trial is about to begin.
Kittens, Tims, Rats, Vixen. These strange, incongruous words, no doubt small in-jokes among the nuclear insiders, labelled some of the most secret and, in the end, most damaging activities from the 11 years of British nuclear testing in Australia. Hundreds of tests fell under the heading ‘minor trials’, a constant since Emu Field, culminating in Vixen B. While mushroom clouds announced the major trials, the minor trials were more shadowy. And much more deadly.
Were the minor trials the most dangerous scientific experiments in Australia’s history? In the case of Vixen B, the evidence is strong. These experiments were covered in unprecedented secrecy, far more so than the major trials. In part this reflected the growing unpopularity of the weapons program at Maralinga and the growing international constraints on testing. Indeed it’s likely that secrecy surrounded Vixen B more for political than for military or national security reasons, and these tests may not have been possible without it. Had the general public been aware of the danger of Vixen B, the political backlash might even have swept the Menzies government from power, given its shaky standing at that time in the polls. (At the December 1961 federal elections, just over a year after Vixen B got underway, the government suffered a significant electoral downturn and was returned with a majority of just one seat.)
History has judged the minor trials harshly. They left by far the biggest portion of the radioactive contamination in Australia and were the subject of an active cover-up by the British, as New Scientist journalist Ian Anderson later revealed (see chapter 11). Lorna Arnold said, ‘The minor trials had left more trouble behind them than the big explosions’. They could have been carried out in the UK but for politics. Noah Pearce was in the team conducting the trials. When Counsel Assisting Peter McClellan suggested to him at the Royal Commission that ‘the planning foundation for your work was that radioactive contamination of Australia may be politically acceptable but not for the UK’, Pearce’s answer was a simple ‘Yes’. This was not disclosed to the Australian people at any time during the experiments.
Might the experiments have been conducted more safely if they had been held in the UK? Probably, given the more rigid regulations and more intrusive and active media there. The experience was different, too, when the UK did similar experiments with the US in Nevada under the name Roller Coaster. Radiation scientist Peter Burns later observed, ‘The Americans had a much more intensive assessment of the fallout by taking many samples. They had labs on site at Nevada so they could take soil samples and do their measurements… they were determined to find every bit of plutonium on the ground so they did a very detailed study of what was there’. Greater rigour, far more extensive documentation and monitoring, and a proper clean-up afterwards: so different from Maralinga, where large quantities of plutonium were left lying around in the open.
The aftermath of the minor trials dominated the media stories that emerged in the late 1970s. In the mid-1980s, the McClelland Royal Commission condemned them, which boosted the momentum of criticism. ALP deputy leader Tom Uren, who remained angry about the trials for many years, and outspoken nuclear veterans such as Avon Hudson, also raised their profile. The courts heard multiple claims from nuclear veterans, some seeking compensation for health problems caused by alleged contamination from Vixen B.
Nearly all the minor trials tested how radioactive and other toxic substances would react when burned or exploded. Different substances were used in each series, including beryllium, uranium and several isotopes of plutonium, as well as short-lived radio-nuclides such as polonium-210, lead-212 and scandium-46, which the Royal Commission found had decayed ‘to insignificant amounts’ since the time of the tests.
The first Kittens trials at Emu Field were intended to test ‘initiators’ – mechanisms within the atomic assembly that switch on the supply of neutrons to enable a chain reaction. The experiments concerned timing the release of neutrons used by a fission weapon to split the atom. The five Emu Field Kittens experiments used the toxic (but non-radioactive) element beryllium as well as the short-lived radioactive element polonium, releasing both into the local environment. William Penney said the Kittens experiments were undertaken in Australia rather than in the UK ‘since they could be done in conditions where dispersal of the short-lived radioactive material used in the initiating of the nuclear explosion would not pose a hazard’.
Rats and Tims were held at Maralinga. The Rats experiments measured how materials were compressed under the high pressure inside a nuclear warhead when it was detonated. Tims was similar to Rats but used a different measurement method. In the Tims experiments, one of the materials measured was plutonium, so Tims left more significant contamination.
They were initially called minor trials, and this was followed by other innocuous names – in 1959 there were ‘assessment tests’ and from January 1960 the Maralinga Experimental Programme, often abbreviated to MEP. Justice James McClelland commented on the ‘almost comical touch of camouflage in the changes of name of the minor trials’, especially given the ban on nuclear tests being negotiated at the time.
Vixen B investigated questions about safety of storage and transportation of nuclear material. How would bombs and related paraphernalia behave if, for example, a plane laden with nuclear warheads crashed on take-off? The ‘broken arrow’ scenario – ‘an unexpected event involving nuclear weapons that results in the accidental launching, firing, detonating, theft or loss of the weapon’ – loomed large after several crashes of aircraft carrying atomic weaponry. Since 1950, a large (and mostly secret) array of accidents involving nuclear weaponry had occurred, sparking fears of a nuclear catastrophe caused by accident or terrorism.
When Vixen B was first planned in 1958, Britain had undertaken six years of atomic weaponry testing, and its nuclear arsenal was sufficiently advanced to go into operational deployment. Blue Danube was a tactical nuclear weapon (soon to be replaced by the smaller Red Beard), deployed to the RAF. When the Vixen B series began in 1960, Britain had rejoined the newly amenable Americans and, among other things, embarked upon a series of similar tests. The US Roller Coaster tests, which examined environmental dispersal of plutonium, had slightly narrower objectives to Vixen B, but similar methods. The Vixen B tests in Australia explicitly addressed the broken arrow scenario in addition to plutonium dispersal. Some people also suspected that Vixen B was more than just a safety test series. According to nuclear engineer Alan Parkinson, ‘While they were said to be to test the safety of nuclear weapons in storage or transit, there was also an element of weapons development in these trials’. The data from Vixen B are still retained by the UK Ministry of Defence, long after the 30-year rule, meaning no-one is entirely sure exactly what they found or how it was used for weapons development.
The 12 Vixen B experiments at Taranaki between 1960 and 1963 involved blowing up plutonium-239 with conventional explosives. Nuclear warheads were strapped on feather beds 2 metres above the ground and subjected to so-called one-point safety trials. This meant detonating one point in a matrix of, say, 32 points of high explosive that must all explode in a rapid sequence to ignite an atomic blast. The plutonium was contained within the bundle of explosives. When the explosive was detonated, the plutonium was compressed and became molten. Plutonium is pyrophoric – it burns on contact with air – and when blown up it produced an aerosol of plutonium oxide particles that spread out from the Taranaki site. Narrow plumes of plutonium aerosol stretched many kilometres out in a hand-like shape over the northwest to northeast. The one-point trials were intended to show that igniting one point in the matrix would not set off the nuclear fission of an atomic blast and apparently succeeded in doing so, at least for low-yield weaponry.