1940

Plutonium

• In December 1940, Glenn Seaborg and his team
• made neptunium-238 in their cyclotron
• by bombarding uranium-238 with deuterons.
• Neptunium-238 decays, with a half-life
• of two and a half days, by negative beta emission
• leaving plutonium-238, which has a longer half-life—
• eight-seven years and two-hundred seventy days—
• and is fissile—it easily breaks apart
• when hit by a slow-moving neutron, resulting
• in a nuclear chain-reaction
• as its neutrons hit other nearby plutonium atoms,
• releasing a huge amount of energy and radiation.

Atomic number 94

• All isotopes of plutonium
• are radioactive.
• Plutonium-244 has a half-life
• of 80.8 million years.
• Plutonium-228 has a half-life
• of a little over a second.
• Plutonium-238 with its high decay heat
• powered spacecraft and landers.

Manhattan Project

• The discovery of plutonium
• was kept secret until 1948.
• In December 1940,
• World War II had already begun.
• Franklin D. Roosevelt approved
• production of nuclear bombs in October 1941.
• Production of plutonium and uranium
• for nuclear bombs proceded concurrently.
• The X-10 Graphite Reactor at Oak Ridge
• irradiated uranium to produce plutonium.
• Facilities at Hanford
• separated plutonium from the uranium.
• B Reactor at Hanford produced
• plutonium for weapons used during the war.

P.U.

• Glenn Seaborg said that their little joke—choosing
• the abbreviation Pu instead of Pl—was hardly noticed.