50 Fun Facts About Plutonium

What is plutonium's chemical symbol?

Glenn Seaborg reportedly chose the letters as a joke on the interjection 'P U' for a bad smell.

What is plutonium's atomic number?

It is the element with the highest atomic number known to occur in nature.

Plutonium was named after which body, which was considered a planet at the time?

Uranium and neptunium had been named after the two preceding planets.

Where was plutonium first synthesised, in 1940-41?

The University of California team bombarded uranium-238 with deuterons in the 60-inch cyclotron.

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

McMillan, Segrè, Kennedy and Wahl were the other members.

Why was publication of the discovery delayed until 1948?

The paper had been sent to Physical Review in March 1941.

Seaborg originally considered what alternative name for the element?

'Ultimium' and 'extremium' were also floated by others, in the mistaken belief it was the last possible element.

Enrico Fermi's team wrongly claimed to have discovered element 94 in 1934 and gave it what name?

The sample actually contained fission products, mainly barium and krypton, since fission was still unknown.

How many allotropes does plutonium normally exhibit?

A seventh, zeta, forms at high temperature within a limited pressure range.

In moist air, plutonium's oxides and hydrides can expand a sample by up to how much?

The flaking powder is pyrophoric, igniting spontaneously in air.

What is plutonium's melting point?

Its boiling point is an unusually high 3,228 °C, giving a huge liquid range.

Unusually, what happens to plutonium's density when it melts?

The liquid also has very high viscosity and surface tension for a metal.

Alloying plutonium with a small amount of which metal stabilises the soft delta phase at room temperature?

Aluminium or cerium also work; the delta form is roughly as strong and malleable as aluminium.

Which isotope of element 94 is the main fissile one used in weapons and reactors?

Uranium-233 and uranium-235 are the other two primary fissile isotopes.

What is the half-life of plutonium-239?

A 5 kg mass produces about 9.68 watts of heat from alpha decay.

Fission of one kilogram of plutonium-239 can release an explosion equivalent to how much TNT?

That energy is what makes it useful in both bombs and reactors.

Which isotope's high spontaneous fission rate limits a sample's usefulness in weapons?

Its percentage determines whether plutonium is weapons-grade, fuel-grade or reactor-grade.

Weapons-grade plutonium contains less than what percentage of plutonium-240?

Fuel-grade is 7-19% and reactor-grade 19% or more; 'supergrade' below 4% is used in US Navy weapons.

Plutonium-238 is used as a heat source in what kind of device on spacecraft?

Its 87.7-year half-life and alpha emission make it warm enough to glow red hot without cooling.

Which pair of 1977 spacecraft carry plutonium-238 power sources that started at 500 watts each?

Three decades after launch, each RTG still produced about 300 watts, and both probes were operating into the 2020s.

How many plutonium-powered pacemakers were reported still implanted in US patients by the end of 2007?

There had been between 50 and 100 in 2003; lithium cells replaced them.

One kilogram of plutonium-238 generates roughly how much heat?

A sheet of paper is enough to shield against its alpha particles.

The natural fission reactor at Oklo, where trace plutonium-239 occurs, is in which country?

It forms when uranium-238 captures neutrons from other spontaneously fissioning uranium atoms.

Plutonium-244 has a half-life of about how long, the longest of any transuranic nuclide?

Evidence of its former presence in the early Solar System has been found in meteorites.

Plutonium has been detected in the spectrum of which chemically peculiar celestial object?

Astrophysical detection of the element is otherwise extremely limited.

Roughly how many atmospheric and underwater nuclear tests left plutonium traces in most humans?

Most such testing ended with the 1963 Limited Test Ban Treaty, though France continued until 1974 and China until 1980.

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

Fermi's graphite-and-uranium pile sat on a racket court under Stagg Field's west stands.

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

Oak Ridge did uranium enrichment and Los Alamos designed the weapons.

What was the first production pile to make plutonium-239, which went online at Oak Ridge in 1943?

It was built at Oak Ridge; the industrial-scale Hanford B Reactor followed in 1945.

Workers nicknamed the huge canyon-like plutonium separation buildings at Hanford after what?

They were 800 feet long and operators worked behind seven feet of concrete using periscopes and TV monitors.

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

Segrè found the problem within ten days of receiving the first reactor-bred sample in April 1944.

The Trinity test device, codenamed 'Gadget', contained how much plutonium?

About 20% of it fissioned, releasing the equivalent of roughly 20,000 tons of TNT.

What was the name of the polonium-beryllium initiator at the heart of the Trinity bomb?

It showered the compressed plutonium sphere with neutrons at the moment of implosion.

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

Hiroshima's 'Little Boy' had used uranium instead.

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

It was released only after the atomic bombs had been announced.

With a tamper reflecting neutrons, plutonium's critical mass falls from 16 kg to about how much?

That is a sphere about 10 cm across, roughly a third of the critical mass of uranium-235.

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

Daghlian received about 5.1 sieverts and died 25 days later; Slotin died nine months after him.

What material is probably most effective at putting out a plutonium fire?

It cools the metal and blocks oxygen; plutonium is usually kept under a dry inert gas.

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

Prevailing winds carried the plume into populated areas northwest of the city; it was not publicly reported until the 1970s.

Between 1945 and 1947, how many human subjects were injected with plutonium without informed consent?

The episode, chronicled in The Plutonium Files, is now considered a serious breach of medical ethics.

Which president ordered the release of records on the secret plutonium injection experiments in 1993?

The Advisory Committee on Human Radiation Experiments concluded in 1995 that 'wrongs were committed'.

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.

How much of the plutonium in MOX fuel is burned after four years in a light water reactor?

MOX has been in use since the 1980s and is widely used in Europe.

Roughly how many tonnes of plutonium are still produced each year as a by-product of nuclear power?

As much as 1,000 tonnes may be in storage worldwide.

Nader said a pound of plutonium dust could kill 8 billion; Bernard Cohen put the figure at no more than what?

Cohen concluded its toxicity is roughly equivalent to nerve gas.

What fraction of ingested plutonium oxide is absorbed by the body?

Inhalation is far more dangerous than swallowing it, and no one is known to have died from either.

Which alloying element in weapons-grade plutonium could interfere with its use in a light water reactor?

It is the same metal used to stabilise the delta phase for machining.

US Navy weapons stored near crews use 'supergrade' plutonium with less than what share of plutonium-240?

Its lower radioactivity is safer for sailors living alongside the warheads.

The oldest known sample of weapons-grade plutonium was found in 2004 in a safe buried where?

Isotope analysis showed it had been made in the X-10 reactor in 1944.

Plutonium was first made in 1940-41 by bombarding uranium-238 with which particles?

The deuteron strike in Berkeley's 60-inch cyclotron produced neptunium-238, which beta-decayed into plutonium-238.