The front page of the Times of India of August 7, 1945, carried the headline World’s deadliest bomb hits Japan: Carries blast power of 20,000 tons of TNT. For millions around the world, headlines of that sort would have been their first intimation of the process of nuclear fission on a large scale.
But, a careful stratigrapher, who studies layers in the soil or rock, might be able to discern that, in fact, nuclear fission had occurred in July 1945. The stratigrapher would just have to look for plutonium at Crawford Lake in Ontario, Canada, the site proposed as the “golden spike” spot to mark the start of the Anthropocene (recognising the problems with its definition as highlighted in Down To Earth’s interview with Amitav Ghosh).
What happened in July 1945 was, of course, Trinity, the world’s first nuclear weapon test, now familiar to many through the film Oppenheimer. A group of researchers recently reconstructed how the plutonium released during that explosion would have been transported by the wind. They calculated that direct radioactive fallout from that test would have reached Crawford Lake within four days of the test, “on July 20, 1945 before peaking on July 22, 1945”.
Since Crawford Lake is nearly 3,000 kilometres from the Trinity test site in New Mexico, it stands to reason that many other places would also have received radioactive fallout from the Trinity test. Now consider the fact that there have been at least 528 nuclear weapon tests around the world that took place above the ground, plus the bombs dropped on Hiroshima and Nagasaki—and you can easily imagine how radioactive fallout must have fallen practically everywhere, whether on land or in the oceans.
Not included in the abovementioned list of 528 is the debated 1979 “Vela incident” that most likely involved an Israeli nuclear weapon test with help from South Africa. It is described as debated only because political elites in the United States, whose Vela satellite 6911 detected a double-flash of light that is characteristic of nuclear explosions, did not want to impose sanctions on Israel.
In 2018, two scientists collected a range of evidence consistent with such a nuclear test, importantly cases of radioactive element iodine-131 that was found in the thyroids of some sheep in 1979—in the south east part of Australia, across the oceans. Again, proof that radioactive fallout from nuclear weapon tests spread out globally.
But it is not just nuclear weapons tests. Accidents at nuclear power plants, too, have produced radioactive fallout that has contaminated the peoples of the world. Radioactive cesium released by the 1986 Chernobyl reactor explosion was found in multiple countries across Western Europe. Yet again, sheep, this time in England, Scotland and Wales, were contaminated, and for a time scientists could not even understand the behaviour of the radioactive cesium that the sheep were ingesting.
Even without nuclear weapons explosions and reactor accidents, people around the world are exposed to radioactive materials—from reprocessing plants. These facilities chemically process the irradiated spent fuel from nuclear power plants, while also producing very large volumes of liquid and gaseous radioactive effluents. These effluents are released into the air; exposure to these constitutes the largest component of the radiation dose to “members of the public from radionuclides released in effluents from the nuclear fuel cycle”.
But underground nuclear weapon tests do, sometimes, vent, releasing radioactive materials into the air. After the Limited Test Ban Treaty of 1963, all US nuclear weapons tests were designed to completely contain the radioactivity underground. Nevertheless, 105 of them vented radioactive materials into the atmosphere. A further 287 tests had “operational releases” whereby radioactivity was released during routine post-test activities. Similarly, several hundred underground nuclear weapons explosions at the Novaya Zemlya test site in the Soviet Union released radioactivity into the atmosphere.
Radioactive materials from these releases spread far and wide. In 1970, radioactive materials vented during the Baneberry test were detected as far as Canada; but Canadian diplomats told US officials that “they had no intention to make a formal protest or to conceive of the event as a violation” of the Limited Test Ban Treaty.