49 Fun Facts About Plutonium

What is plutonium's chemical symbol?

Pu: the team leader picked the letters as a joke about a bad smell, expecting to be overruled, but nobody objected and the symbol became official.

Plutonium is named for Pluto, which in turn takes its name from the Roman god of what?

The underworld: the name simply continued a run of planet-named elements, yet a god of the dead proved a grimly fitting namesake for the metal of the atomic bomb.

Where was plutonium first synthesised, in 1940-41?

Berkeley, California: the university's laboratory went on to find so many new elements that two of them, berkelium and californium, carry the names of the town and the state.

Which chemist led the team that first produced and identified plutonium?

Glenn T. Seaborg: he broke the news of two further elements on a children's radio quiz show in 1945, days before the formal announcement, after a young panellist asked whether any more had been found.

Why did the paper announcing plutonium's discovery go unpublished for years?

Wartime secrecy: the team sent its paper to Physical Review in March 1941, but it was held back on security grounds, and the public first heard the word plutonium only after the atomic bombings of 1945.

Which element, found months earlier in the same laboratory, sits just before plutonium in the periodic table?

Neptunium: Edwin McMillan made element 93 in 1940 and began hunting for element 94, but he was called away to defence work on radar, leaving his colleagues to finish the job.

Which Italian physicist's team wrongly reported finding element 94 in 1934, later calling it hesperium?

Enrico Fermi: his samples were really fragments of split uranium atoms, so he had achieved nuclear fission four years before anyone recognised it, and his 1938 Nobel Prize cited those supposed new elements.

What are plutonium's six different solid forms called?

Allotropes: plutonium's six differ so much in density that a warming piece swells and shrinks, which makes the metal notoriously hard to machine.

Which 1985 film's time machine runs on plutonium its inventor conned out of Libyan terrorists?

Back to the Future: Doc Brown's DeLorean needs plutonium to generate 1.21 gigawatts, so Marty, stranded in 1955 without any, has to catch a lightning bolt to get home.

Which country's first nuclear test, in 2006, used plutonium from a reactor it had once agreed to freeze?

North Korea: it shut its Yongbyon reactor under a 1994 deal with the United States, restarted it after the deal broke down in 2002, and tested a plutonium bomb four years later.

Which physicist directed the laboratory that designed the first plutonium bomb?

J. Robert Oppenheimer: he urged that the bomb's scientists be gathered at one isolated site, and the Army took over a remote boys' school on a mountain mesa to house them.

What fruit-inspired name do weapon designers give the plutonium core of a nuclear warhead?

The pit: it sits like a peach stone at the centre of the weapon, and in a modern hydrogen bomb the plutonium is only the trigger that sets off the far larger fusion stage.

Which element, one step beyond plutonium in the periodic table, is found in many household smoke detectors?

Americium: it builds up as plutonium-241 decays, and a tiny speck in an alarm charges the air so that a current flows until smoke gets in the way.

What is the half-life of plutonium-239?

24,100 years: half of any sample is still there after that long, which is why plutonium waste is buried deep in rock instead of being stored until it fades.

Enola Gay dropped the first atomic bomb; which B-29 dropped the second, a plutonium weapon, three days later?

Bockscar: named for its usual commander, Frederick Bock, it could not reach its reserve fuel that day and had just enough left to limp to Okinawa after the drop.

Plutonium would detonate too early in a gun-type bomb, so Fat Man relied on which method instead?

Implosion: shaped explosive charges squeezed a plutonium sphere from every side at once, a design so uncertain that it had to be proven in the desert before anyone would trust it in combat.

Which country's first nuclear test, 1974's 'Smiling Buddha', used plutonium from a Canadian-supplied research reactor?

India: it called the blast a peaceful nuclear explosion, but the shock led supplier countries to form a club to stop reactor plutonium being diverted to bombs again.

Which of these Mars rovers runs on a plutonium-powered generator instead of solar panels?

Curiosity: its radioisotope thermoelectric generator turns the heat of decaying plutonium-238 into electricity, so the rover keeps working through the nights and dust storms that starve solar panels.

Which twin spacecraft have run on plutonium-238 generators since their launch in 1977?

The Voyagers: their generators lose about four watts of output every year as the plutonium decays, so engineers have switched off heaters and instruments one by one to keep the mission going.

Before lithium batteries took over, plutonium-238 powered which implanted medical device?

Heart pacemakers: a plutonium cell could outlast its wearer and spare repeat surgery to change batteries.

Plutonium's radioactivity consists mainly of which type of radiation?

Alpha particles: a sheet of paper stops them, so the plutonium-238 in a spacecraft generator needs almost no shielding and nearly all of its energy stays behind as usable heat.

What made plutonium at Oklo, Gabon, nearly two billion years before humans did?

A natural reactor: groundwater seeping through rich uranium ore set off chain reactions that ran on and off for hundreds of thousands of years, and the plutonium they made stayed put.

Which plutonium-powered probe flew past Pluto in 2015, the dwarf planet its fuel is named after?

New Horizons: nine years out from the Sun and far beyond the reach of solar panels, the probe ran its cameras on one plutonium generator putting out about 200 watts.

A plutonium fuel cask from which Apollo mission lies on the Pacific seabed instead of the Moon?

Apollo 13: the generator fuel meant for a lunar experiment stayed aboard the lander the crew used as a lifeboat, and its cask survived re-entry intact before sinking in deep water.

Traces of plutonium in most people come mainly from what?

Open-air bomb tests: hundreds of blasts in the atmosphere spread plutonium around the globe until a 1963 treaty drove most testing underground.

The first self-sustaining chain reaction, CP-1, was achieved in December 1942 under a football grandstand in which city?

Chicago: the pile of graphite and uranium was stacked in a disused squash court beneath the stands, in the middle of a crowded city, and its data shaped the first plutonium-making reactors.

Where was the Manhattan Project's main plutonium production facility?

Hanford, Washington: planners wanted somewhere isolated with abundant water and power, and the reactors went up along the Columbia River, whose flow cooled them.

What went wrong at a secret Soviet plutonium plant in the 1957 Kyshtym disaster?

A waste tank exploded: its cooling had failed at Mayak, a plutonium works so secret that it was known only by the code name Chelyabinsk-40.

Workers building 800-foot plutonium separation plants in 1944 nicknamed them after which ocean liner?

The Queen Mary: inside each long concrete 'canyon', operators worked behind seven feet of shielding, steering the machinery by periscope and television because the process was too radioactive to approach.

Which gun-type plutonium weapon design was abandoned because reactor plutonium had too much plutonium-240?

Thin Man: stray neutrons from plutonium-240 would have started the chain reaction before a gun could bring the pieces together, so in summer 1944 the weapon laboratory was reorganised around a new design.

What was the code name of the first plutonium bomb test, in July 1945?

Trinity: as the shock wave passed, one physicist let scraps of paper fall and judged the bomb's power from how far they were blown, an estimate that fell well short of the true figure.

In 1966 a US bomber crash scattered plutonium over farmland at Palomares, in which country?

Spain: four hydrogen bombs fell from the stricken B-52, two burst open on the fields without a nuclear blast, and one sank offshore, where the US Navy needed nearly three months to recover it.

Which Japanese city was hit by the plutonium bomb 'Fat Man' on 9 August 1945?

Nagasaki: the bomber's first target that morning was Kokura, but smoke and cloud hid the city, so the crew flew on to its second choice.

The existence and name of plutonium were first made public in which document?

The Smyth Report: issued three days after the second bomb fell, this official history gave the public its first account of how the weapon was made, with a foreword warning readers not to ask the project's people for more.

What name is given to the smallest amount of plutonium that can sustain a nuclear chain reaction?

Critical mass: for a bare ball of plutonium-239 it is only about 10 kg, a sphere roughly 10 cm across, which is why plants strictly limit how much may sit in one place.

The plutonium sphere that killed Harry Daghlian and Louis Slotin in 1945-46 is known as what?

The demon core: both men were nudging it toward a chain reaction by hand, a stunt nicknamed tickling the dragon's tail, and after the second death such experiments were run by remote control.

Where in the body does absorbed plutonium mostly settle, staying for decades?

The bones and liver: once lodged there it leaves so slowly that it irradiates nearby tissue for decades, which is why the worry is cancer years later, not sudden poisoning.

Contamination of the Denver area came mainly from 1957 and 1969 plutonium fires at which plant?

Rocky Flats: the plant made the plutonium 'triggers' that set off hydrogen bombs, and after a multibillion-dollar cleanup most of the site became a national wildlife refuge.

Who were the eighteen people secretly injected with plutonium by US doctors between 1945 and 1947?

Hospital patients: doctors chose people they believed were dying, but some were misdiagnosed, and one, a house painter named Albert Stevens, lived another 21 years.

Which president ordered the release of records on the secret plutonium injection experiments, decades after they ended?

Bill Clinton: he acted after the Albuquerque Tribune tracked down and named the victims in 1993, a series that won reporter Eileen Welsome a Pulitzer Prize.

What is the most common reprocessing method for extracting plutonium and uranium from spent fuel?

The recovered material can be made into mixed oxide (MOX) fuel for reuse.

What name is given to a reactor designed to make more plutonium fuel than it burns?

A breeder reactor: its spare neutrons turn the common, unburnable form of uranium into fresh plutonium, promising far more energy from the same ore.

Which NASA probe drew protests at its 1997 launch over the 33 kg of plutonium it carried?

Cassini: protesters feared a launch accident would scatter its plutonium, but the probe left safely and its three generators kept it working at Saturn until 2017.

Physicist Bernard Cohen offered to eat plutonium on television to rebut which activist's claim about its deadliness?

Ralph Nader: he had said a pound of plutonium could kill eight billion people, so Cohen offered to eat as much of it as any leading critic would eat of caffeine, but no network took him up on it.

Which route makes plutonium most harmful to the body?

Inhaling: its radiation cannot get through skin and the gut absorbs almost none of what is swallowed, but dust breathed in lodges in the lungs and irradiates them from within.

Weapons-grade plutonium is alloyed with a little of which metal to keep it soft enough to shape?

Gallium: best known for melting in a warm hand, it locks plutonium into its soft delta form, sparing machinists a brittle metal that swells and cracks as it changes structure.

Which plutonium-plant whistleblower died in a 1974 car crash a week after plutonium was found on her skin?

Karen Silkwood: a technician at an Oklahoma plutonium fuel plant, she was reportedly gathering evidence of safety lapses for her union, and Meryl Streep played her in the 1983 film of her story.

Which chemical company built the first plutonium factory for a fee of just one dollar?

DuPont: stung by charges of profiteering after the First World War, the firm waived any profit and vowed to leave the bomb business once the war ended.

Plutonium was first made in 1940–41 using which kind of machine?

Cyclotron: the 60-inch machine fired deuterons, the nuclei of heavy hydrogen, at uranium to make a short-lived element that decayed within days into the first plutonium.