With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Plutonium reacts with an element.
text_B: Plutonium is a transuranic radioactive chemical element with symbol Pu and atomic number 94 .. transuranic. transuranium element. radioactive. radioactive. chemical element. chemical element. symbol. chemical symbol. atomic number. atomic number. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air , and forms a dull coating when oxidized .. actinide. actinide. metal. metal. oxidized. plutonium( IV ) oxide. The element normally exhibits six allotropes and four oxidation states .. It reacts with carbon , halogens , nitrogen , silicon and hydrogen .. carbon. carbon. nitrogen. nitrogen. silicon. silicon. hydrogen. hydrogen. When exposed to moist air , it forms oxides and hydrides that can expand the sample up to 70 % in volume , which in turn flake off as a powder that is pyrophoric .. pyrophoric. pyrophoricity. It is radioactive and can accumulate in bones , which makes the handling of plutonium dangerous .. radioactive. radioactive. Plutonium was first produced and isolated on December 14 , 1940 by Dr. Glenn T. Seaborg , Joseph W. Kennedy , Edwin M. McMillan , and Arthur C. Wahl by deuteron bombardment of uranium-238 in the 60-inch cyclotron at the University of California , Berkeley .. Glenn T. Seaborg. Glenn T. Seaborg. Joseph W. Kennedy. Joseph W. Kennedy. Edwin M. McMillan. Edwin M. McMillan. Arthur C. Wahl. Arthur C. Wahl. uranium-238. uranium-238. cyclotron. cyclotron. They first synthesized neptunium-238 -LRB- half-life 2.1 days -RRB- which subsequently beta-decayed to form a new element with atomic number 94 and atomic weight 238 -LRB- half-life 87.7 years -RRB- .. atomic number. atomic number. neptunium-238. neptunium-238. half-life. half-life. neptunium. neptunium. Uranium had been named after the planet Uranus and neptunium after the planet Neptune , and so element 94 was named after Pluto , which at the time was considered to be a planet as well .. Uranium. Uranium. Uranus. Uranus. neptunium. neptunium. Neptune. Neptune. Pluto. Pluto. Wartime secrecy prevented them from announcing the discovery until 1948 .. Plutonium is the element with the highest atomic number to occur in nature , as trace quantities similarly arise from natural uranium-238 capturing neutrons .. atomic number. atomic number. uranium-238. uranium-238. Plutonium is much more common on Earth since 1945 as a product of neutron capture and beta decay , where some of the neutrons released by the fission process convert uranium-238 nuclei into plutonium-239 .. uranium-238. uranium-238. neutron capture. neutron capture. beta decay. beta decay. neutron. neutron. fission. nuclear fission. plutonium-239. plutonium-239. Both plutonium-239 and plutonium-241 are fissile , meaning that they can sustain a nuclear chain reaction , leading to applications in nuclear weapons and nuclear reactors .. plutonium-239. plutonium-239. plutonium-241. plutonium-241. fissile. fissile. nuclear chain reaction. nuclear chain reaction. Plutonium-240 exhibits a high rate of spontaneous fission , raising the neutron flux of any sample containing it .. neutron. neutron. fission. nuclear fission. Plutonium-240. Plutonium-240. spontaneous fission. spontaneous fission. neutron flux. neutron flux. The presence of plutonium-240 limits a plutonium sample 's usability for weapons or its quality as reactor fuel , and the percentage of plutonium-240 determines its grade -LRB- weapons-grade , fuel-grade , or reactor-grade -RRB- .. grade. reactor-grade plutonium. weapons-grade. weapons-grade. Plutonium-238 has a half-life of 88 years and emits alpha particles .. half-life. half-life. Plutonium-238. Plutonium-238. It is a heat source in radioisotope thermoelectric generators , which are used to power some spacecraft .. spacecraft. spacecraft. Plutonium isotopes are expensive and inconvenient to separate , so particular isotopes are usually manufactured in specialized reactors .. Producing plutonium in useful quantities for the first time was a major part of the Manhattan Project during World War II that developed the first atomic bombs .. Manhattan Project. Manhattan Project. World War II. World War II. The Fat Man bombs used in the Trinity nuclear test in July 1945 , and in the bombing of Nagasaki in August 1945 , had plutonium cores .. Fat Man. Fat Man. Trinity. Trinity ( nuclear test ). nuclear test. nuclear test. bombing of Nagasaki. bombing of Nagasaki. Human radiation experiments studying plutonium were conducted without informed consent , and several criticality accidents , some lethal , occurred after the war .. Human radiation experiments. Human radiation experiments. informed consent. informed consent. Disposal of plutonium waste from nuclear power plants and dismantled nuclear weapons built during the Cold War is a nuclear-proliferation and environmental concern .. plutonium waste. nuclear waste. dismantled nuclear weapons. nuclear disarmament. Cold War. Cold War. nuclear-proliferation. nuclear proliferation. Other sources of plutonium in the environment are fallout from numerous above-ground nuclear tests , now banned .. plutonium in the environment. plutonium in the environment. fallout. nuclear fallout. banned. Partial Test Ban Treaty
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