In June 1984, Walsh addresses parliament after receiving a chronology of the British nuclear tests that he commissioned from the physicist John Symonds, a consultant to his department. Symonds will later prepare an exhaustive account of the British tests for the Royal Commission. In this parliamentary statement, Walsh refers to the particularly problematic minor trials:
It is clear that it is these trials, and particularly the Vixen B series, which involved the use of plutonium, that produced the major source of radiological contamination which remains of concern at Maralinga today. One would assume that the Australian governments of the day were aware of the nature of these tests. However, Australian documents examined to date do not enable us to determine this.
This hints at the revelations to come in the Royal Commission, when Justice James McClelland – Diamond Jim – will begin the process of making public just how little the Australian Government actually did know at the time. Walsh announces the Royal Commission into the British nuclear tests on 5 July 1984. In his media release, he says the inquiry is charged in particular with examining ‘measures that were taken for protection of persons against the harmful effects of ionising radiation and the dispersal of radioactive substances and toxic materials as judged against standards applicable at the time and with reference to standards of today’.
Investigative journalists have begun sniffing around, including Howard Conkey and Paul Malone from the Canberra Times. Conkey writes to Walsh in June 1984 seeking clarification on the contaminated material found by the ARL team. Walsh replies on 28 June, ‘The present concerns with the newly identified fragments arise from the recognition that this material could be moved from its present site in an uncontrolled way (for example, picked up in the tyre tread of a motor vehicle)’.
At Maralinga, in that mild desert May of 1984, the scientists have been amazed and shocked at their findings. Over time they will become a little angry as well, particularly when their senior colleague John Moroney crunches the Roller Coaster data in the early 1990s. Williams, Burns and Moroney will be sources for Ian Anderson’s landmark story in New Scientist in 1993 on the British deceit about contamination at Maralinga. His role in the Anderson story will be Moroney’s last act in relation to Maralinga – within days of the story he will die from multiple myeloma. In the end, science, journalism, politics and the anger of veterans will all play a role in uncovering the shadowy Cold War story of the Maralinga desert nuclear test range. To find out how we got to this point, we need to go back to the birth of atomic weaponry.
2
Britain’s stealthy march towards the bomb
I’d learned by the bitter path that to touch the pitch of secrecy was to be contaminated for a very long time, that governments and politicians wanted not men who believed in the integrity of natural knowledge but men who would tell them what they want to hear, and that the truth has no meaning for a Churchill … [or] a Menzies, if it is politically inconvenient.
Professor Marcus (Mark) Oliphant, Australian physicist, 1956.
Secrecy was not only a guard against enemies but a barrier between allies. It caused much wartime ill-will between Britain and the United States.
Margaret Gowing, official historian of the British nuclear energy and weapons development programs, 1978.
‘Now I am become death, destroyer of worlds.’
J Robert Oppenheimer, physicist and leader of the Manhattan Project, quoting from Hindu scripture, as the first atomic weapon was tested at Alamogordo, New Mexico, 1945.
Britain came to the red sand of Maralinga through a series of contingent events. These ranged over politics and geography, colonial legacies and scientific pragmatism. One of the most significant factors was Britain’s early dominance in nuclear weapons development. Britain incubated the atomic bomb. Although she quickly lost custody to the US, Britain’s strong and distinguished tradition of physics research was the foundation for the terrifying weapons that shook the world and reshaped geopolitics after World War II.
British scientific history lays claim to some of the greatest minds in the field, including the father of modern physics, Sir Isaac Newton. At prolific laboratories, such as the Cavendish Laboratory at Cambridge University and the Department of Physics at the University of Birmingham, modern nuclear physics had some of its greatest advances. This is, after all, a story about physics as much as anything else, because physics made nuclear weaponry possible. Many physicists were later conflicted by this, first when atomic weapons killed tens of thousands of Japanese civilians and then when the weapons grew in strength and number until they could destroy our planet many times over.
British physicists were involved at all levels of the push to build the bomb. The country also welcomed and protected many Jewish physicists escaping persecution in Nazi Germany. These refugees found their professional contributions and lives were valued, working with colleagues on this most secret and challenging of problems. Physicists working in Britain drew together the disparate strands from the burgeoning field of nuclear physics – particularly essential research conducted in Paris just before the war – and came up with an ominous synthesis. In short, British physics initially powered the US Manhattan Project, the staggering scientific and technological effort that took just six years to develop the atomic bomb that was loaded into the bomb-bay of an operational aircraft in August 1945.
To understand the British tests in Australia we need to understand the British role in the Manhattan Project. The project drew upon substantial American expertise and technical wizardry, but the British provided the early intellectual boost. Tube Alloys, the world’s first atomic weapon development program, exemplified the British approach to developing the bomb. It buried a world-changing scientific research project under an obfuscating and boring bureaucratic name. The Tube Alloys Directorate was established in September 1941, and it continued after the war in several different guises. The secret research and development organisation with its deliberately misleading title quietly worked in a series of nondescript university laboratories and, later, dingy industrial workshops. No big, expensive infrastructure was involved. The can-do and well-funded Americans made the first operational bomb on the back of some remarkable work done on a shoestring in Britain under the banner of Tube Alloys and the Maud Committee that predated it. Debate still rages over whether this was a good thing or not, but either way it happened. The rapid-fire research of the Tube Alloys Directorate was transferred to the US, where it continued on to a dramatic conclusion under a far more recognisable name, the Manhattan Project.
The Manhattan Project changed the world. On 6 August 1945, this secret wartime project came to fruition in the most shocking way when the first atomic bomb was dropped on Hiroshima, followed, three days later, by a different kind of atomic bomb on Nagasaki. Exact figures are disputed, but at least 185 000 people died, either immediately or in the months directly after. Single bombs have never created so many casualties. The physics that enabled this broad-scale killing emerged at the beginning of the war; the atomic bombs played a role in ending it.
At the beginning of World War II the US president Franklin Roosevelt received an exceptionally important letter signed by Albert Einstein, the world’s best known and possibly greatest physicist. Leo Szilard and Eugene Wigner, both European refugee physicists based in the US, had drafted this epochal missive. The letter urged the president to investigate a totally new kind of bomb, a weapon that would exploit the process of nuclear fission, later known to many as splitting the atom. The atom to be split was from the remarkable element uranium.
This idea had gained its theoretical underpinnings in the late 1930s, so the science was new and almost entirely untested. Like a nuclear chain reaction, though, knowledge began exploding out of the initial idea. As noted by Margaret Gowing, the great historian of British atomic science, between January and June of 1939 over 20 papers were published on uranium in the prominent journal Nature alone. Military secrecy soon closed down publication as the wo
rk was recognised as strategically valuable and dangerous. But, for a while, an army of nuclear physicists, who saw what power might be unlocked by breaking the forces holding a uranium atom together, joined the frenzy to share their results.
Uranium, nature’s ‘heaviest’ element (that is, with the most matter in its nucleus), had virtually no practical use before 1938 when the Berlin-based German scientists Otto Hahn and Fritz Strassmann formulated a theory of nuclear fission that exploited its unique properties. Hahn, a chemist, built upon theoretical work he had done with the Austrian physicist Lise Meitner the year before and also on research in Paris that established basic understanding of how a uranium atom could be split and what happened when it was. Uranium was already known to bristle with many more neutrons than protons, but the Paris group showed that uranium atoms fling out some of the extra neutrons when they are ‘split’. At first the Hahn–Strassmann theory held only intellectual interest, because no-one thought that the energy produced by cleaving an atom could be harnessed and controlled. Nevertheless, the theory led quickly to related ideas of chain reaction and critical mass, explained below, that would, in a practical sense, make a bomb possible. Niels Bohr and John Wheeler published a memorandum on the fission process just three days before the outbreak of the war in Europe that gave scientific impetus to the notion of a nuclear weapon. This, according to Gowing, effectively ‘put all belligerents at the same theoretical starting point in the pursuit of an atomic bomb’.
Soon, as the almost unimaginable possibilities presented themselves, both Allied and Axis governments started to crack down on the free publication of this growing body of scholarly research. Some scientists, notably Szilard, believed that publication should be stopped voluntarily, and he encouraged other scientists to refrain from publication even before government-imposed secrecy took over. In the first few months of the war in Europe, as uranium fission research was taken over by government entities and as scientists recognised the gravity of these many new insights, publication ceased altogether. This alerted the Soviet Union to the fact that the science had shifted to the military, and they deployed spies to crack the secret knowledge. The spy rings were forming even before the scientists knew how far their research would take them, and they proved to be devastatingly effective once the bomb moved from theory to reality.
The science can be simply stated. An atom has a nucleus consisting of protons, which have a positive charge, and neutrons, which have no charge. Electrons, which have a negative charge, surround this nucleus. Strong forces hold the nucleus together – forces far stronger than those that hold the electrons around it. The number of protons in its nucleus determines the atomic number of each element, its position on the Periodic Table and its chemical properties. However, the nuclear properties of the atom vary depending on the number of protons and neutrons. The key to understanding how nuclear bombs work is the neutron. For heavy atoms with high atomic numbers, the fact that protons have a positive charge becomes significant, because objects with the same electrical charge repel each other. A large nucleus, such as that of uranium, is full of positively charged particles all pushing each other away. Extra neutrons are needed to stabilise it. Therefore, heavy elements tend to have more neutrons than protons in their nuclei. Some heavy elements are known as fissionable, which means their nuclei can be split. Of the fissionable elements, a small number are known as fissile, because they can readily sustain a nuclear chain reaction. Natural uranium-238, the most abundant isotope, is fissionable, but the rarer uranium-235 is fissile.
Uranium-235 was the essential isotope for the early development of the atomic bomb. If you bombard uranium with neutrons, when the beam of neutrons hits the nucleus, it reacts. As the neutron enters the uranium nucleus at great speed, it splits the nucleus apart violently into two roughly equal fragments, hence the popular phrase splitting the atom. Each fragment has approximately half the mass and half the nuclear charge of the original substance, and the process releases a staggering amount of energy. The pioneer of fission, Otto Frisch, along with his aunt Lise Meitner, calculated it as 200 million electron volts, evenly divided between the two new fragments. These fragments rapidly fly away from each other, carrying their energy with them.
Uranium-235, as a rare fissile element, has an odd number of neutrons (143), which means that for complex physical reasons it can more easily sustain a chain reaction than uranium-238. In effect, it is almost impossible to induce an explosive chain reaction in uranium-238, but relatively straightforward in uranium-235. The neutrons released by uranium-235 following fission can be catapulted into another uranium-235 nucleus, causing a cascade of fissions as atoms are split by the neutrons flung out from a preceding reaction. Each successive round of fissions is stronger than the one that came before. This is a chain reaction. As Gowing put it, ‘The reaction will spread from atom to atom through the mass of fissile material. Each fission of a uranium atom results in the release of over a million times as much energy as in the combustion of a carbon atom. A pound of uranium, therefore, if completely fissioned, would yield as much energy as several million pounds of coal’.
Critical mass refers to the fact that a certain threshold amount of fissile material is needed to sustain a chain reaction. More material is needed than will actually react, because not all neutrons that split out of the first reaction actually go on to split other nuclei. Some just depart from the reaction without further interaction. Material reaches critical mass when more neutrons are able to go off and split other nuclei than are lost in the reaction. In the early atomic weapons, just a few pounds of uranium-235 were needed to reach critical mass. Physicists began to grasp these insights into fission, critical mass and chain reaction only in the 1930s, but they came together at exactly the moment in history that they could, for better or worse, be acted upon.
When Einstein, Szilard and Wigner sent their doomsday letter to Roosevelt in August 1939, just days before the war began in Europe, they didn’t tell him they were proposing an unsubstantiated idea. Most physicists at that point did not actually believe such a weapon was possible, largely because only a tiny fraction of natural uranium is actually fissile – which meant it would take tonnes of the stuff to have enough material to start a nuclear chain reaction. The letter immediately piqued the president’s interest not least because it was signed by Einstein. In October 1939 Roosevelt ordered the creation of the Advisory Committee on Uranium, and the American atomic bomb effort got its tentative start.
By then, more important developments were afoot in the UK, unknown at first to Roosevelt and his newly created uranium committee. Physicists Otto Frisch and Rudolf Peierls concluded that the physics problems associated with achieving critical mass were not insurmountable, if the isotope uranium-235 could be separated from natural uranium-238. The physicists, both Jewish refugees (Frisch was Austrian, Peierls German), were working at the University of Birmingham in England. They deduced that uranium-235 would achieve fast critical mass with only a pound or two of the material, effectively resolving the technological stumbling block to a nuclear weapon. They wrote a memorandum outlining their findings, the famous Frisch–Peierls Memorandum. The canny Australian physicist Marcus Oliphant, usually known as Mark (later Sir Mark), working at the same university, made sure that the right people at the heart of the British Government came to know immediately what was in that brief (three-page) document. This world-changing memorandum began modestly:
The possible construction of ‘super-bombs’ based on a nuclear chain reaction in uranium has been discussed a great deal and arguments have been brought forward which seemed to exclude this possibility. We wish here to point out and discuss a possibility which seems to have been overlooked in previous discussions.
Frisch and Peierls then made a simple and eloquent case for a bomb made from a small quantity of uranium-235. The device they described would have two separate lumps of the substance that would be rammed together when detonated to instigate a chain reaction. Their words reveal
a moment in science when educated insight precipitates a leap forwards in human knowledge. They had no applied research to back up what they were saying. They had their reasoning ability combined with their knowledge base. It was enough.
The scientists also speculated on what might happen if such a bomb were exploded in the real world:
Any estimates of the effects of this radiation on human beings must be rather uncertain because it is difficult to tell what will happen to the radioactive material after the explosion. Most of it will probably be blown into the air and carried away by the wind. This cloud of radioactive material will kill everybody within a strip estimated to be several miles long. If it rained the danger would be even worse because active material would be carried down to the ground and stick to it, and persons entering the contaminated area would be subjected to dangerous radiations even after days. If 1% of the active material sticks to the debris in the vicinity of the explosion and if the debris is spread over an area of, say, a square mile, any person entering this area would be in serious danger, even several days after the explosion.
In calm language, the scientists were explaining a bomb never before seen. This nightmarish weapon would not just have a huge explosive impact but would go on harming people long after its detonation, and well beyond ground zero. Such a bomb would change the course of any conflict. If these scientists hounded from Nazi Germany could envisage such a weapon, so could the dozen or more highly capable physicists who were still there, all of whom could read the recent outpouring of scientific literature and follow their own intellectual intuitions. This fact haunted the Allies throughout the war, and with good reason. Despite efforts by the British to buy up stocks of available uranium oxide when the possibilities of this previously useless material became apparent, the Germans succeeded in getting their hands on significant quantities. That could mean only one thing.
Atomic Thunder Page 5