Moroney was one of the few to recognise the significance of Roller Coaster, joint US–UK tests that were similar to Vixen B. The main difference was that during the Roller Coaster experiments a much greater effort had been made to accurately measure the level of plutonium contamination. The thoroughness of the Roller Coaster documents contrasted with the paucity of information for Vixen B – at least, the information made available to Australia. Moroney described the Roller Coaster data: ‘Typically, they are thorough records of the Operation, going into infinite detail’.
Moroney provided the data that made the New Scientist story possible, based on documents from the National Technical Information Service in Washington DC. He had been through each and every page of these mostly microfiche documents, recording and analysing as he went. Moroney analysed about 2500 pages of declassified nuclear contamination data from the US–UK Roller Coaster trials in Nevada (held in May and June of 1963, after the British had resumed weapons testing with the Americans). While some details of the tests remained classified (as Moroney said in a letter to Pat Davoren, ‘There are still wraps around the main core of Roller Coaster data, with a few bits sticking out for mere mortals like us to see’), he had enough to understand their significance. The Roller Coaster data enabled Moroney to make a detailed scientific case that the British atomic test authorities had knowingly left substantial and potentially dangerous amounts of plutonium on or near the surface in parts of Maralinga.
The Americans conducted a range of top-secret ‘safety trials’ that investigated the one-point problem that had sparked the British Vixen B program, in a program of what they called hydronuclear experiments. Many of these trials were conducted in the early 1960s at Los Alamos. Roller Coaster was part of this broad program but was conducted (with input and participation from AWRE personnel) in Nevada and specifically examined environmental dispersal of plutonium when simulated warheads were detonated using conventional explosives. Roller Coaster was made up of four trials, held on 15 May, 25 May, 31 May and 9 June 1963. The first two were atmospheric tests, similar to Vixen B (although the cloud created in the first did not rise as high as that in Vixen B). The other two were held in bunkers. In the atmospheric tests, most of the plutonium travelled downwind as an oxide aerosol, just like it did in the Vixen B tests. The Americans were surprised by how much plutonium contaminated the steel plate in several of the tests and thoroughly studied this phenomenon. This same outcome from the Vixen B safety trials became apparent only during the 1984 ARL trip to Maralinga, even though it was there to be seen in the immediate aftermath. The actual amounts of plutonium used in each of the US tests were still classified at the time of Moroney’s analysis, but he was able to postulate how much was used ‘with reasonable accuracy’ because of his knowledge of Vixen B: ‘The Roller Coaster data… and the… data for the five identified plumes at Taranaki agree very nicely, given the differences in the firings, and the span of cloud heights and wind speeds’. In other words, Moroney was sure that Roller Coaster and Vixen B could be usefully compared. While Roller Coaster and Vixen B yielded different official results, the American results were more robust and realistic. The Vixen B figures made no sense unless Moroney factored in a gross underestimate of actual contamination at Taranaki. When he saw what the data meant, he made his switch from stalwart AWTSC man to disillusioned critic.
The discrepancy could not be explained away by different ways of doing things, between countries and across the years. By the time the ARL scientists were on the ground at Maralinga in 1984, the measurement and analysis methods to which they had access were far superior to those available to Noah Pearce and his colleagues who prepared the AWRE report in 1968 that cleared the UK of any further responsibility at Maralinga. The ARL scientists used gamma ray detectors to measure a product of plutonium decay, americium-241, which could be extrapolated to give an exact measurement of plutonium. As Anderson explained in his story, ‘The British had to rely on alpha particle emissions from plutonium which are difficult to detect’. But, as radiation scientist Peter Burns also pointed out in the story, ‘They could have done radiochemistry analysis of the soil which would have given a more accurate reading of plutonium’. In addition, the British had had the results of the Roller Coaster trials, so they would have known the likely levels of plutonium.
Not long before his death in 1993, Moroney, who planned to write what he knew, prepared several aides memoire to this end. They reveal that he was always careful to ensure that the latter-day reader would understand the mindset of the times that led to the creation of the Maralinga test site. ‘A major ingredient in depicting the general background is to convey some sense of the perceptions of the period, which, I suppose, allowed these nuclear tests to be conducted essentially as military operations, with the expectation on personal compliance and commitment that this implies.’
A long period of analysis of the Maralinga site had ensued after the 1984 ARL visit. The ARL scientists discovered a major discrepancy between the levels of contamination claimed in the Pearce Report and what they found on the ground, sparking years of investigation that culminated with Moroney’s detailed examination of Roller Coaster records. The americium-241 levels obtained by the ARL scientists showed the Pearce Report data about plutonium levels were incorrect. Moroney’s analysis of Roller Coaster later confirmed that they were in error by a factor of 10. While the Pearce Report claimed that about 20 of the 22 kilograms of plutonium had been buried, an estimated 20 kilograms was later found to be scattered around the site.
MARTAC, set up in 1993 to oversee clean-up of contamination at the site, extended and corroborated the readings from the 1984 ARL visit and Moroney’s analysis. The MARTAC team found the ‘contamination of the lands consisted of fine particulate of plutonium and fragments of paraffin wax, lead, light alloys and plastic with plutonium plated on them’. In other words, the site was a dangerous mess. MARTAC also noted that ‘it was the experimental set-up of the Vixen B trials that made them the principal source of lasting environmental contamination’.
Moroney heard from Williams about the prospective New Scientist story and was keen to co-operate. By then he had been crunching the Roller Coaster numbers for a couple of years, and sending what he had found to his Australian Government contacts, notably Pat Davoren, then manager of the Test Site Management Unit of the Department of Primary Industries and Energy. He also started preparing a briefing paper in response to the developing New Scientist story. He noted that the ‘inadequacies and gross inconsistencies’ in the set of plutonium field data used for Operation Brumby ‘were not resolved between the UK and Australia at the time, even after extended re-analysis and debate’. This absence of proper contamination data for the site was a catastrophe. Moroney maintained that it was not a simple mistake. The Roller Coaster results meant that the ‘AWRE knew of… the error involved’, but these results ‘were the subject of military security at the time and not accessible to Australia’.
These errors resulted in considerable confusion and misinformation about plutonium contamination at Maralinga. The Roller Coaster trials gave Moroney the ammunition he needed to support the Australian Government in rejecting the 1968 agreement. In a letter to Davoren on 28 November 1991, Moroney gave his ‘fast first pass through the Roller Coaster information’. Before commencing RADSUR, the 1966 radiological survey, and Brumby, the 1968 clean-up, he concluded, the AWRE certainly knew that » α-survey [alpha-survey] monitoring of Pu [plutonium] fallout on soil can be expected to underestimate the Pu surface density by an order of magnitude, even when the survey is made in the day or so immediately following deposition; and