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SOPHIA OF WISDOM III - PLUTONIUM - PACEMAKERS
THE LIBRARY OF SOPHIA OF WISDOM III
THE SOPHIA OF ALL SOPHIA OF WISDOMS
AKA
CAROLINE E. KENNEDY____________________________
SEPTEMBER 27, 2006
RE: PLUTONIUM
Plutonium (IPA: /ˌplu˘°ˈtəʊniəm/) is a radioactive, metallic chemical element. It has the symbol Pu and the atomic number 94. It is the element used in most modern nuclear weapons. The most important isotope of plutonium is 239Pu, with a half-life of 24,110 years. It can be made from natural uranium and is fissile. The most stable isotope is 244Pu, with a half-life of about 80 million years, long enough to be found in extremely small quantities in nature. In fact 244Pu is the heaviest atom naturally occurring in traces on the Earth's crust.
Contents [hide]
1 Notable characteristics
2 Applications
3 History
4 Occurrence
4.1 Manufacture
4.1.1 Pu-239
4.1.2 Pu-238
5 Compounds
6 Allotropes
7 Isotopes
8 Precautions
8.1 Toxicity
8.2 Disposal difficulties
8.3 Criticality potential
8.4 Flammability
9 Plutonium in popular culture
10 See also
11 References
12 External links
[edit] Notable characteristics
Plutonium has been called "the most complex metal" and "a physicist's dream but an engineer's nightmare"[1] for its peculiar physical and chemical properties. It has six allotropes normally and a seventh under pressure, each of which have very similar energy levels but with significantly varying densities, making it very sensitive to changes in temperature, pressure, or chemistry, and allowing for dramatic volume changes following phase transitions (in nuclear applications, it is usually alloyed with small amounts of gallium, which stabilizes it in the delta-phase.)[2] Plutonium is silvery in pure form, but has a yellow tarnish when oxidized. It is also notable in that it possesses a low-symmetry structure causing it to become progressively more brittle over time. [3] Because it self-irradiates, it ages both from the outside-in and the inside-out.[2] However, self-irradiation can also lead to annealing which counteracts some of the aging effects. In general, the precise aging properties of plutonium are very complex and poorly understood, greatly complicating efforts to predict future reliability of weapons components.
The heat given off by alpha particle emission makes plutonium warm to the touch in reasonable quantities; larger amounts can boil water. [citation needed] It displays five ionic oxidation states in aqueous solution:
PuIII, as Pu3+ (blue lavender)
PuIV, as Pu4+ (yellow brown)
PuVI, as PuO22+ (pink orange)
PuV, as PuO2+ (thought to be pink; this ion is unstable in solution and will disproportionate into Pu4+ and PuO22+; the Pu4+ will then oxidize the remaining PuO2+ to PuO22+, being reduced in turn to Pu3+. Thus, aqueous solutions of plutonium tend over time towards a mixture of Pu3+ and PuO22+.) [4]
PuVII, as PuO52- (dark red); the heptavalent ion is rare and prepared only under extreme oxidizing conditions.
The actual color shown by Pu solutions depends on both the oxidation state and the nature of the acid anion, which influences the degree of complexing of the Pu species by the acid anion. [5]
[edit] Applications
The isotope 239Pu is a key fissile component in nuclear weapons, due to its ease of fissioning and availability. The critical mass for an unreflected sphere of plutonium is 16 kg, but through the use of a neutron-reflecting tamper the pit of plutonium in a fission bomb is reduced to 10 kg, which is a sphere with a diameter of 10 cm. The Manhattan Project "Fat Man" type plutonium bombs, using explosive compression of Pu to significantly higher densities than normal, were able to function with plutonium cores of only 6.2 kg.[6] Complete detonation of plutonium will produce an explosion equivalent to the explosion of 20 kilotons of trinitrotoluene (TNT) per kilogram.[citation needed] (See also nuclear weapon design.) However, complete detonation requires an additional neutron source (often from a small amount of fusion fuel), and primitive bombs may be far less efficient. For example, despite the 6.2 kg of plutonium, the Fat Man yield was only 21 kt.
Plutonium could also be used to manufacture radiological weapons or as a radiologic poison. In a number of instances damaged nuclear weapons have spread plutonium over a surrounding area, similar to the effect of a so-called "dirty bomb", and required extensive cleanup. On the other hand, 5 kg of plutonium was spread over the Nagasaki area (due to incomplete fission) and never cleaned up. The toxicity of plutonium is in dispute; nuclear industry advocates point to the low chemical toxicity of plutonium and ability of a worker to hold a kilogram brick of the material without protection; if inhaled or digested, however, plutonium's effects due to radioactivity overwhelm the effects of plutonium's chemical interactions with the body, and the LD50 dose drops to the order of 5ug/kg. The insistence on both sides of the issue of plutonomium's safety/deadliness casts questions on the current habitability of areas that have been exposed to nuclear warfare and on the health of the current residents.
The plutonium isotope 238Pu is
an alpha emitter with a half-life of 87 years.
These characteristics make it well suited for electrical power generation for devices which must function without direct maintenance for timescales approximating a human lifetime. It is therefore used in radioisotope thermoelectric generators such as those powering the Cassini and New Horizons (Pluto) space probes; earlier versions of the same technology powered seismic experiments on the Apollo Moon missions.
238Pu has been used successfully to power artificial heart pacemakers,
to reduce the risk of repeated surgery. It has been largely replaced by Lithium based primary cells, but as of
2003
there were somewhere between 50 and 100 plutonium-powered pacemakers still implanted and functioning in living patients.
PLUTONIUM
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