Plutonium
In 1952, the Periodic Table that covered our exam questions had plutonium, atomic number 94, on it. It also had americium, curium, berkelium and californium but all these were faint, made of dots, faded as though they were ghosts of elements rather than the elements themselves.
It was exciting to know that scientists were still “discovering” new elements. They described what they were doing as “discovering”; I had no idea that they were actually manufacturing them nor that they existed for mere seconds or milliseconds. To my eight-year-old mind, their “discovery” meant that they were part of the basic building blocks of the universe. I was now primed for more elements, for more atomic “discoveries”!
In fact, uranium is the last element natural to our environment; all elements with atomic numbers greater than 92 were or would be created, would be artificial, transient, and radioactive.
Uranium was first isolated in 1789. A German chemist, Martin Klaproth, isolated it from pitchblende ore. He named it “uran” in honour of a recently discovered seventh planet from the sun, Uranus.
Martin had no knowledge of nuclear physics; he did not know that uranium had an atomic number of 92 for the 92 protons in its nucleus and the 92 electrons flying around it. A hundred and fifty years later when Manhattan project scientists created an element with 93 protons in its nucleus, they named it “neptunium” (Np) after the eighth planet from the sun. It was natural for them to name element number 94 “plutonium” after then-ninth-planet Pluto[1].
Planet Pluto itself was named for the god of the underworld, and of the afterlife. Pluto was also the god of wealth because gold and silver came from the ground. It was an apt name for a long-lived and entirely manufactured element that would become the sought-after explosive for atomic bombs.
Both neptunium and plutonium[i] were formed by bombarding uranium-238 with neutrons in a cyclotron.
Scientists knew that uranium-235 was fissile bomb-making material; its disadvantage for this purpose was that nearly 50 kg were required to make an explosive device. Furthermore, natural uranium was mostly U238. Being less than 5% of natural uranium, it required time-consuming processes to be enriched to a bomb-making concentration greater than 90%. Scientists didn’t feel that they had “lots of time”. They also knew that a heavier element was theoretically possible.
Element 93, neptunium, was not fissile, but it spontaneously and quickly (two days half-life) decayed by beta emission into element 94, plutonium, which proved to be fissile. Only eleven kilograms, a 4-inch diameter sphere of plutonium-239 would be needed to make a bomb.
The race was on to isolate it, characterize it and weaponize it. Scientists at Los Almos, New Mexico, worked with quantities so small that they could not see them. They could only trace them by following their radioactivity. The history of the “radium girls” was in their minds so they watched contamination rigorously. They worked in a highly ventilated and filtered atmosphere, submitted to “nose wipes” that were checked for radioactivity, and tried to recover every spilled atom of plutonium.
It is clear from the records kept by Dr. Hempelmann, the medical doctor in charge of the health team, that measures to protect the staff were not taken for simple humanitarian reasons – he, Oppenheimer and another physician, Stafford Warren, were concerned about lawsuits. Studies with plutonium in rats indicated that the element was a “bone-seeker” like radium and also that it accumulated in the liver. Compared to radium, it was excreted much more slowly which meant that it stayed in the body longer. Having a longer biological half-life meant greater exposure to radioactivity.
One of their other early discoveries was the difficulty in keeping it contained. They couldn’t even see the element, but it got onto their shirt cuffs, soles of shoes, laboratory doorknobs and their own faces.
On August 1, 1944, a chemist, Don Mastick, had an accident that illustrates the concern that the laboratory had about their plutonium samples.
Don’s equipment was miniature – his test tubes were the size of darning needles. He was working with microscopic quantities when he opened a tiny vial containing 10 mg of plutonium[2] dissolved in acid. Because gas had accumulated in the vial, it exploded onto the wall, his face and his clothing. He tasted the acid.
He immediately went to the medical clinic across the road. His face was washed and the water saved. His mouth was swished and the spittle saved. His stomach was pumped twice and the contents saved. In fact, as the only chemist working in isolation of plutonium, after these decontamination procedures, Don was given all the washings to return to the laboratory and retrieve the plutonium. All but 1 microgram (one thousandth of a milligram) was recovered. That one microgram in his body was enough to blow the ionization chamber off-scale for days after the accident with his breath and, thirty years later, still be detectable in his urine!
Plutonium is an unusual element. When pure plutonium is exposed to air it quickly forms hydrides and oxides and can expand massively to 70% more that its original volume. The flakes are pyrophoric meaning that they can spontaneously ignite. It reacted chemically in such different ways that it was easy to separate from its parent element, uranium-238.
John Gofman had isolated 1.2 milligrams of plutonium from 2 tons of uranium in a cyclotron in autumn, 1942. It took six weeks of neutron bombardment[3] and a further three weeks to chemically isolate it (at this time, every step had to be invented; they were just beginning to learn about its characteristics). In liquid form, the 1.2 mg had a volume equal to ¼ of a teaspoon.
Clearly, for bomb construction, they need a faster process. Enrico Fermi created a primitive nuclear reactor in Chicago, the Chicago Pile 1, to demonstrate that a sustained reaction could be obtained. An Oak Ridge reactor was in construction and would be functioning by November 1943 to deliver plutonium to Los Almos the following year.
By this time, the uranium bomb had been designed as a “gun-type” device. A half sphere of uranium was “shot” using a conventional explosive into another half-sphere to create a critical mass which would explode. Scientists needed to work on a different device because the desired plutonium isotope, Pu239, was contaminated with another isotope, Pu240, which just fizzles along and interfers with the explosive quality of Pu239.
They came up with a different device, an implosion bomb that brought the bits of plutonium forcibly together by a circle of explosive charges. Once united, they reached criticality and would explode.
They weren’t entirely sure that it would work as planned and arranged to test it. The Trinity Test was secretive, allegedly done “where there were no people or animals”. In the highly secretive wartime atmosphere, General Groves’ pre-prepared press release lied about the detonation, seen and felt up to 100 miles away like this: “A remotely located ammunition magazine containing a considerable amount of high explosives and pyrotechnics exploded.”
Thirty miles away farm animals and cattle lost the hair on their backs – it regrew white. The army purchased these animals and allegedly took them to Los Almos and Oak Ridge to follow their health. Some researchers claim that there may have been human fetal loss of up to 52% using state statistics. It was not, in fact, an unpopulated location and many of the rural people in the area consider themselves to be the first victims of nuclear weapons.
One thousand miles away, the Eastman Kodak officials reported furiously that their unexposed film had been contaminated by radioactive particles, presumably from Wabash River water. Any delusions about limited radioactive fallout were dashed from the first atomic bomb blast.
When the Manhattan project scientists were working with it, plutonium was code-named as “the Product”. Dogs, cats, rats and rabbits were injected, forced to breath plutonium-contaminated air or fed plutonium. Those that received the largest doses sickened and died. Pregnant animals aborted or eventually delivered small or deformed babies. Large numbers of lab animals were sacrificed in numerous studies. This was not enough to establish plutonium’s toxicity.
They wanted human subjects to test “the product”. They didn’t know how quickly people could excrete it, whether through urine or feces. They knew that radioactivity caused a decline in blood cells but they didn’t know how quickly it might happen with plutonium. They explained that human experiments “were needed to see how to apply the animal data to human problems”[ii].
At this point, the story of plutonium slips into the bizarre.
While they determined that the human subjects sought needed to be suffering from incurable diseases but have close to normal kidney function in order to study excretion of plutonium in urine and feces, their first victim was a "well developed...well nourished" "colored male"[iii] who had been involved in a motor-vehicle accident. He was employed as a construction worker from the Oak Ridge site of the Manhattan project.
It is very unclear why he was chosen because he was noted to have “somewhat diminished”[iv] kidney function. Perhaps he was only a victim of opportunity. His motor-vehicle accident occurred on the Oak Ridge site.
Ebb Cade was 55 years old. He had multiple broken bones which left untreated for three weeks in order prepare for the experiment. The bones were surgically reduced five days after the plutonium was given an opportunity to “settle” in and on them. During the surgery, physicians were able to determine that plutonium did indeed go to bones.
Their study was badly flawed because they failed to keep the pre-injection urine and feces separate from the post-injection products
When describing the experiment in a classified talk, perhaps in an attempt to assuage his guilt, one of the researchers described Ebb as “an elderly male whose age and general health was such that there is little or no possibility that the injection can have any effect on the normal course of his life”[v]. No mention was made of his employment or of his broken bones. No mention is made of his subsequent health until his death in 1953 from “ventricular fibrillation following heart failure”[vi] at the age of 63. No consent for the experiment was ever sought and no information was given by the researchers to his wife or family.
The next patient was Arthur Hubbard, a retired businessman with an aggressive squamous cell cancer. He received 6.5 micrograms of plutonium intravenously and his urine and stool samples were collected thereafter. Arthur’s cancer was well advanced so he fit their criteria.
The third patient was Albert Stevens, a fifty-eight-year-old house painter. He was presumed to have a limited lifespan with stomach cancer. He had normal kidney function, an “ideal candidate for the experiment”. He was injected with Pu238, a more radiotoxic isotope of plutonium but more readily measured than Pu239 with the instruments of the 1940’s.
Four days after the injection, with plutonium coursing throughout his body, Albert went to surgery for removal of his “carcinomatous mass”[vii]. When the pathologist could not find any evidence of cancer, the entire team was shocked. Albert lived for another 21 years; there seems to be no comment about his general health although he had received one of the largest test doses of plutonium.
Neither Arthur nor Albert nor their families were sought for permission nor were they ever told about the experimental nature of their injections. Arthur died shortly after the injection; Albert died of heart failure at age 79.[viii]
There were a total of eighteen victims of plutonium injections. They received poor follow-up, their initial health conditions were so varied that it was impossible to establish a baseline, and of course, none of them were informed or asked to sign releases.
Lying, obfuscation and secrecy kept the experimenters connected and established the foundation for denial of health effects of ionizing radiation. This was true for both scientists and politicians who supported research and continuing development of nuclear bombs.
There have been and will continue to be many more victims of Trinity, Hiroshima[ix] and Nagasaki.
Minute traces of plutonium are now found in every human body on earth. More than 550 atmospheric and underwater nuclear tests have been carried out and some dozen or more major nuclear accidents have contaminated the globe.
While scientists with the Manhattan Project were unable to establish the health effects of relatively small exposures to plutonium, they certainly knew the effects of large exposures through some of the criticality accidents in their research labs.
A critical reaction is one that is self-sustaining, a reaction that only needs “moderating” to continue, a reaction where the numbers of neutrons produced effect the further release of the same numbers of neutrons. A nuclear power plant is said to go “critical” when it is “turned on” to create the heat necessary to boil water.
A “criticality accident” occurs when an accidental uncontrolled, unmoderated chain reaction occurs. According to Wikipedia, there have been sixty criticality accidents recorded since 1945[x].
In order to determine the exact amount of plutonium required to explode, scientists experimented by bringing pieces of plutonium into close proximity to one another. They also tried various means to increase the number of neutrons released from the plutonium core by using various elements as “reflectors”. The experiments were called “tickling the dragon’s tail”.
On two well known occasions, scientists received fatal doses of radiation when their experiments went critical. Since both men were using the same plutonium core and running trials less than a year apart, that core gained the name, “the demon core”. It was later melted down for use in other bomb tests.
Both men, Harry Daghlian and Louis Slotin, received estimated radiation doses greater than 5 Sv. Both men received the best possible medical care, specialists flown to the site hospital from across the United States. Their families were also notified and flown to their bedside knowing that they would not live. Both died painful prolonged deaths, their bodies bloating and edematous as cell walls broke apart, their minds disordered, excruciating diarrhea as the linings of their guts became part of their feces.
Harry’s accident occurred less than three weeks after the bombs were dropped on Hiroshima and Nagasaki. His agonizing death took 25 days. All the scientists and highest-ranking military men could not avoid knowing that some people would die this way when bombed in an atomic war.
Louis actually moved closer to the reaction, possibly to protect the other people in the room. He died nine days later.
We heard nothing about these experiments in 1952; the information was classified.
Later, in 1958, Cecil Kelley’s death was also classified. Cecil was a chemist, a technician working in a plutonium-separation laboratory. He received an estimated 36 Seiverts exposure when a plutonium acid bath that he was mixing went critical. Since exposure to 5 Sv was considered a universally fatal dose for humans, medical staff knew that Cecil would die and considered him an “experiment of opportunity”. Repeated blood samples, catherization of his bladder and even a bone marrow biopsy of his sternum were done without permission. Every moment of his life was recorded.
The blood samples taken six hours after the accident showed that he no longer had white blood cells; a bone marrow examination produced only acellular red watery substance. He had been knocked unconscious initially, had a very brief period of lucidity before he slipped into a coma and died 35 hours later. He was autopsied and more than eight pounds of body parts and tissues were removed from his body. His wife was not informed of the accident until after his death, nor was her permission sought for either the autopsy or removal of organs. His cause of death was recorded as “congestive heart failure”.
Plutonium, like its namesake, the god of the underworld, afterlife, and wealth, was powerful. Dangerous to handle, it grabbed the hearts and minds of countless brilliant people. Even as it continues to leak poisonously into the environment, more is constantly being created. Like heroin, it has become an addiction.
[1] Pluto was demoted from planetary status to “dwarf planet” in August 2006.
[2] Plutonium is very dense. Twenty mg of plutonium occupies 1 cubic mm.
[3] Deuteron was used for bombardment. It is the nucleus of a deuterium atom, one proton and one neutron.
[i] There is argument that plutonium may have been a primordial element because infinitesimal amounts have been found in nature. The counterargument is that they are the result of natural bombardment of uranium-238 by neutrons. Neptunium is entirely of human manufacture.
[ii] Plutonium files p89, from Russell & Nickson, p2 Distribution and Excretion of Plutonium”
[iii] https://en.wikipedia.org/wiki/Ebb_Cade. Accessed 13.09.21.
[iv] The Plutonium Files P83
[v] Ibid, p86
[vi] https://en.wikipedia.org/wiki/Ebb_Cade. Accessed 13.09.21
[vii] “Description of Operation” June 6, 1945, Stevens m.r. Quoted in Plutonium Files P92
[viii] https://bioethicsarchive.georgetown.edu/achre/commeet/meet11/brief11/tab_g/br11g1w.txt Accessed 17.09.21
[ix] “Little Boy”, the bomb that was dropped on Hiroshima, was a uranium-235 bomb. “Fat Man” on Nagasaki was a plutonium-239 bomb.
[x] https://en.wikipedia.org/wiki/Criticality_accident Accessed 21.9.21.
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