Why the Under-Reported Plutonium of Japan Arose Attention?
The Japanese government has not declared about 640 kg of unused plutonium in its annual report for the International Atomic Energy Agency (IAEA) in 2012 and 2013, an amount enough to make 80 nuclear bombs, local media reported Saturday.
Plutonium is a transuranic radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen, silicon and hydrogen. When exposed to moist air, it forms oxides and hydrides that expand the sample up to 70% in volume, which in turn flake off as a powder that canspontaneously ignite. It is radioactive and can accumulate in the bones. These properties make the handling of plutonium dangerous.
Plutonium is the heaviest primordial element by virtue of its most stable isotope, plutonium-244, whose half-life of about 80 million years is just long enough for the element to be found in trace quantities in nature. Plutonium is mostly a byproduct of nuclear reactions in reactors where some of the neutrons released by the fission process convert uranium-238 nuclei into plutonium.
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-240 exhibits a high rate of spontaneous fission, raising the neutron flux of any sample containing it. 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 (weapons grade, fuel grade, or reactor grade).
Plutonium-238 has a half-life of 88 years and emits alpha particles. It is a heat source in radioisotope thermoelectric generators, which are used to power some spacecraft. Plutonium isotopes are expensive and inconvenient to separate, so particular isotopes are usually manufactured in specialized reactors.
A team led by Glenn T. Seaborg and Edwin McMillan at the University of California, Berkeley, first synthesized plutonium in 1940 by bombarding uranium-238 with deuterons. Trace amounts of plutonium were subsequently discovered in nature. Producing plutonium in useful quantities for the first time was a major part of the Manhattan Project during World War II, which developed the first atomic bombs. The first nuclear test, "Trinity" (July 1945), and the second atomic bomb used to destroy a city (Nagasaki, Japan, in August 1945), "Fat Man", both had cores of plutonium-239. Human radiation experiments studying plutonium were conducted withoutinformed consent, and several criticality accidents, some lethal, occurred during and after the war. Disposal of plutonium wastefrom nuclear power plants and dismantled nuclear weapons built during the Cold War is a nuclear-proliferation and environmental concern. Other sources of plutonium in the environment are fallout from numerous above-ground nuclear tests (now banned).
Japan underreports 640 kg unused plutonium to IAEA
Japan claims to own 44 tons of plutonium, while the actual amount is 45 tons, said Japan's Kyodo News Agency. The unreported plutonium is part of the plutonium-uranium mixed oxide (MOX) fuel placed at an offline reactor in a nuclear plant in Saga Prefecture, southern Japan.
The MOX fuel was loaded in March 2011, shortly before the Fukushima Nuclear Crisis happened later that month. Until two years later, the unused fuel was taken out from the reactor which remained offline.
An official from Japan Atomic Energy Commission argued that the plutonium is considered being used and hence exempt from reporting to the IAEA.
But plenty of experts both abroad and at home criticized the action of the Japanese government for failing to recognize the seriousness of the problem.
"From the safeguards point of view this material is still un- irradiated fresh MOX fuel regardless of its location," former IAEA Deputy Director General Olli Heinonen said. Thus the unreported plutonium could be diverted to as many as 80 nuclear bombs.
Japan keeps the largest number of plutonium among non-nuclear nations. The country used it for power generation in the past, but after the 2011 disaster at the Fukushima, Japan's nuclear reactors remain idle.
The big amounts of plutonium are causing regional worries over Japan's motives, as well as global concerns over the security of these nuclear fuel reserves.
sourceshttp://en.twwtn.com/Bignews/69249.html
Plutonium is a transuranic radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen, silicon and hydrogen. When exposed to moist air, it forms oxides and hydrides that expand the sample up to 70% in volume, which in turn flake off as a powder that canspontaneously ignite. It is radioactive and can accumulate in the bones. These properties make the handling of plutonium dangerous.
Plutonium is the heaviest primordial element by virtue of its most stable isotope, plutonium-244, whose half-life of about 80 million years is just long enough for the element to be found in trace quantities in nature. Plutonium is mostly a byproduct of nuclear reactions in reactors where some of the neutrons released by the fission process convert uranium-238 nuclei into plutonium.
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-240 exhibits a high rate of spontaneous fission, raising the neutron flux of any sample containing it. 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 (weapons grade, fuel grade, or reactor grade).
Plutonium-238 has a half-life of 88 years and emits alpha particles. It is a heat source in radioisotope thermoelectric generators, which are used to power some spacecraft. Plutonium isotopes are expensive and inconvenient to separate, so particular isotopes are usually manufactured in specialized reactors.
A team led by Glenn T. Seaborg and Edwin McMillan at the University of California, Berkeley, first synthesized plutonium in 1940 by bombarding uranium-238 with deuterons. Trace amounts of plutonium were subsequently discovered in nature. Producing plutonium in useful quantities for the first time was a major part of the Manhattan Project during World War II, which developed the first atomic bombs. The first nuclear test, "Trinity" (July 1945), and the second atomic bomb used to destroy a city (Nagasaki, Japan, in August 1945), "Fat Man", both had cores of plutonium-239. Human radiation experiments studying plutonium were conducted withoutinformed consent, and several criticality accidents, some lethal, occurred during and after the war. Disposal of plutonium wastefrom nuclear power plants and dismantled nuclear weapons built during the Cold War is a nuclear-proliferation and environmental concern. Other sources of plutonium in the environment are fallout from numerous above-ground nuclear tests (now banned).
Japan underreports 640 kg unused plutonium to IAEA
Japan claims to own 44 tons of plutonium, while the actual amount is 45 tons, said Japan's Kyodo News Agency. The unreported plutonium is part of the plutonium-uranium mixed oxide (MOX) fuel placed at an offline reactor in a nuclear plant in Saga Prefecture, southern Japan.
The MOX fuel was loaded in March 2011, shortly before the Fukushima Nuclear Crisis happened later that month. Until two years later, the unused fuel was taken out from the reactor which remained offline.
An official from Japan Atomic Energy Commission argued that the plutonium is considered being used and hence exempt from reporting to the IAEA.
But plenty of experts both abroad and at home criticized the action of the Japanese government for failing to recognize the seriousness of the problem.
"From the safeguards point of view this material is still un- irradiated fresh MOX fuel regardless of its location," former IAEA Deputy Director General Olli Heinonen said. Thus the unreported plutonium could be diverted to as many as 80 nuclear bombs.
Japan keeps the largest number of plutonium among non-nuclear nations. The country used it for power generation in the past, but after the 2011 disaster at the Fukushima, Japan's nuclear reactors remain idle.
The big amounts of plutonium are causing regional worries over Japan's motives, as well as global concerns over the security of these nuclear fuel reserves.
sourceshttp://en.twwtn.com/Bignews/69249.html
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