   #copyright

Plutonium

2007 Schools Wikipedia Selection. Related subjects: Chemical elements


              94              neptunium ← plutonium → americium
              Sm
             ↑
             Pu
             ↓
             (Uqq)

                                  Periodic Table - Extended Periodic Table

                                                                   General
                                    Name, Symbol, Number plutonium, Pu, 94
                                                 Chemical series actinides
                                            Group, Period, Block n/a, 7, f
                                                  Appearance silvery white
                      Gloved hands holding a "button" of refined plutonium
                                                   Atomic mass (244) g/mol
                                     Electron configuration [Rn] 5f^6 7s^2
                                Electrons per shell 2, 8, 18, 32, 24, 8, 2
                                                       Physical properties
                                                               Phase solid
                                     Density (near r.t.) 19.816 g·cm^−3
                                   Liquid density at m.p. 16.63 g·cm^−3
                                                    Melting point 912.5  K
                                                 (639.4 ° C, 1182.9 ° F)
                                                      Boiling point 3505 K
                                                    (3228 ° C, 5842 ° F)
                                          Heat of fusion 2.82 kJ·mol^−1
                                   Heat of vaporization 333.5 kJ·mol^−1
                           Heat capacity (25 °C) 35.5 J·mol^−1·K^−1

   CAPTION: Vapor pressure

                                      P/Pa   1    10  100  1 k  10 k 100 k
                                     at T/K 1756 1953 2198 2511 2926 3499

                                                         Atomic properties
                                              Crystal structure monoclinic
                                               Oxidation states 6, 5, 4, 3
                                                       ( amphoteric oxide)
                                    Electronegativity 1.28 (Pauling scale)
                                     Ionization energies 1st: 584.7 kJ/mol
                                                      Atomic radius 175 pm
                                                             Miscellaneous
                                                 Magnetic ordering no data
                              Electrical resistivity (0 °C) 1.460 µΩ·m
                       Thermal conductivity (300 K) 6.74 W·m^−1·K^−1
                       Thermal expansion (25 °C) 46.7 µm·m^−1·K^−1
                               Speed of sound (thin rod) (20 °C) 2260 m/s
                                                    Young's modulus 96 GPa
                                                      Shear modulus 43 GPa
                                                        Poisson ratio 0.21
                                             CAS registry number 7440-07-5
                                                         Selected isotopes

                CAPTION: Main article: Isotopes of plutonium

                               iso    NA    half-life  DM DE ( MeV)   DP
                              ^238Pu syn   88 y        SF -         -
                                                       α  5.5       ^234U
                              ^239Pu syn   24.1×10^3 y SF -         -
                                                       α  5.245     ^235U
                              ^240Pu syn   6.5×10^3 y  SF -         -
                                                       β  0.005     ^240Am
                              ^241Pu syn   14 y        β  -         Am
                                                       SF -         -
                              ^242Pu syn   3.73×10^5 y SF -         -
                                                       α  4.984     ^238U
                              ^244Pu trace 8.08×10^7 y α  4.666     ^240U
                                                       SF -         -

                                                                References

   Plutonium ( IPA: /ˌpluːˈtəʊniəm/) 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.

Notable characteristics

   Plutonium has been called "the most complex metal" and "a physicist's
   dream but an engineer's nightmare" 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.) 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. Because it self-irradiates, it ages both from the outside-in
   and the inside-out. 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. It
   displays five ionic oxidation states in aqueous solution:
     * Pu^III, as Pu^3+ (blue lavender)
     * Pu^IV, as Pu^4+ (yellow brown)
     * Pu^VI, as PuO[2]^2+ (pink orange)
     * Pu^V, as PuO[2]^+ (thought to be pink; this ion is unstable in
       solution and will disproportionate into Pu^4+ and PuO[2]^2+; the
       Pu^4+ will then oxidize the remaining PuO[2]^+ to PuO[2]^2+, being
       reduced in turn to Pu^3+. Thus, aqueous solutions of plutonium tend
       over time towards a mixture of Pu^3+ and PuO[2]^2+.)
     * Pu^VII, as PuO[5]^2- (dark red); the heptavalent ion is rare and
       prepared only under extreme oxidizing conditions.

   Note: The colour 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.

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. Complete
   detonation of plutonium will produce an explosion equivalent to the
   explosion of 20 kilotons of trinitrotoluene (TNT) per kilogram. (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 (not particularly deadly) chemical 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.
   Many of the more extreme claims about plutonium toxicity are
   inconsistent with the past and current habitability of the area and 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 batteries recharged by induction, but as of 2003 there
   were somewhere between 50 and 100 plutonium-powered pacemakers still
   implanted and functioning in living patients.

History

   Glenn Seaborg at the Geiger Counter, 301 Gilman Hall, Berkeley,
   California, where he discovered plutonium.
   Enlarge
   Glenn Seaborg at the Geiger Counter, 301 Gilman Hall, Berkeley,
   California, where he discovered plutonium.

   The production of plutonium and neptunium by bombarding uranium-238
   with neutrons was predicted in 1940 by two teams working independently:
   Edwin M. McMillan and Philip Abelson at Berkeley Radiation Laboratory
   at the University of Berkeley, California and by Norman Feather and
   Egon Bretscher at the Cavendish Laboratory at University of Cambridge.
   Coincidentally both teams proposed the same names to follow on from
   uranium, like the sequence of the outer planets.

   Plutonium was first produced and isolated on February 23, 1941 by Dr.
   Glenn T. Seaborg, Dr. Michael Cefola, Edwin M. McMillan, J. W. Kennedy,
   and A. C. Wahl by deuteron bombardment of uranium in the 60-inch
   cyclotron at Berkeley. The discovery was kept secret due to the war. It
   was named after Pluto, having been discovered directly after neptunium
   (which itself was one higher on the periodic table than uranium), by
   analogy to solar system planet order as Pluto was considered to be a
   planet at the time (though technically it should have been "plutium",
   Seaborg said that he did not think it sounded as good as "plutonium").
   Seaborg chose the letters "Pu" as a joke, which passed without notice
   into the periodic table. Chemists at the University of Chicago began to
   study the newly manufactured radioactive element. The George Herbert
   Jones Laboratory at the university was the site where, for the first
   time, a trace quantity of this new element was isolated and measured in
   September 1942. This procedure enabled chemists to determine the new
   element's atomic weight. Room 405 of the building was named a National
   Historic Landmark in May 1967. During the Manhattan Project, the first
   production reactor was built in Oak Ridge. Later, large reactors were
   set up in Hanford, Washington, for the production of plutonium, which
   was used in the first atomic bomb used at the "Trinity" test at White
   Sands, New Mexico in July 1945. Plutonium was also used in the " Fat
   Man" bomb dropped on Nagasaki, Japan in August 1945. The " Little Boy"
   bomb dropped on Hiroshima utilized uranium-235, not plutonium.

   Large stockpiles of plutonium were built up by both the Soviet Union
   and the United States during the Cold War—it was estimated that 300,000
   kg of plutonium had been accumulated by 1982. Since the end of the Cold
   War, these stockpiles have become a focus of nuclear proliferation
   concerns. In 2002, the United States Department of Energy took
   possession of 34 metric tons of excess weapons-grade plutonium
   stockpiles from the United States Department of Defense, and as of
   early 2003 was considering converting several nuclear power plants in
   the US from enriched uranium fuel to MOX fuel as a means of disposing
   of plutonium stocks.
   Hanford Site plutonium production reactors along the Columbia River
   during the Manhattan Project.
   Enlarge
   Hanford Site plutonium production reactors along the Columbia River
   during the Manhattan Project.

   During the initial years after the discovery of plutonium, when its
   biological and physical properties were very poorly understood, a
   series of human radiation experiments were performed by the U.S.
   government and by private organizations acting on its behalf. During
   and after the end of World War II, scientists working on the Manhattan
   Project and other nuclear weapons research projects conducted studies
   of the effects of plutonium on laboratory animals and human subjects.
   In the case of human subjects, this involved injecting solutions
   containing (typically) five micrograms of plutonium into hospital
   patients thought to be either terminally ill, or to have a life
   expectancy of less than ten years either due to age or chronic disease
   condition. These eighteen injections were made without the informed
   consent of those patients and were not done with the belief that the
   injections would heal their conditions; rather, they were used to
   develop diagnostic tools for determining the uptake of plutonium in the
   body for use in developing safety standards for people working with
   plutonium during the course of developing nuclear weapons.

   The episode is now considered to be a serious breach of medical ethics
   and of the Hippocratic Oath, and has been sharply criticised as failing
   "both the test of our national values and the test of humanity." More
   sympathetic commentators have noted that while it was definitely a
   breach in trust and ethics, "the effects of the plutonium injections
   were not as damaging to the subjects as the early news stories painted,
   nor were they so inconsequential as many scientists, then and now,
   believe."

Occurrence

   While almost all plutonium is manufactured synthetically, extremely
   tiny trace amounts are found naturally in uranium ores. These come
   about by a process of neutron capture by ^238U nuclei, initially
   forming ^239U; two subsequent beta decays then form ^239Pu (with a
   ^239Np intermediary), which has a half-life of 24,110 years. This is
   also the process used to manufacture ^239Pu in nuclear reactors. Some
   traces of ^244Pu remain from the birth of the solar system from waste
   of supernovae, because its half-life (80 million yrs) is fairly long.

   A relatively high concentration of plutonium was discovered at the
   Natural nuclear fission reactor in Oklo, Gabon in 1972. Since 1945,
   about 10 tons (the size of a cube of plutonium metal with 0.77 meter
   sides) have been released onto Earth through nuclear explosions.

Manufacture

Pu-239

   Plutonium-239 is one of the two fissile materials used for the
   production of nuclear weapons and in some nuclear reactors as a source
   of energy. The other fissile material is uranium-235. Plutonium-239 is
   virtually nonexistent in nature. It is made by bombarding uranium-238
   with neutrons in a nuclear reactor. Uranium-238 is present in quantity
   in most reactor fuel; hence plutonium-239 is continuously made in these
   reactors. Since plutonium-239 can itself be split by neutrons to
   release energy, plutonium-239 provides a portion of the energy
   generation in a nuclear reactor.
   A ring of weapons-grade electrorefined plutonium, with 99.96% purity.
   This 5.3 kg ring is enough plutonium for use in a modern nuclear
   weapon.
   Enlarge
   A ring of weapons-grade electrorefined plutonium, with 99.96% purity.
   This 5.3 kg ring is enough plutonium for use in a modern nuclear
   weapon.

Pu-238

   There are small amounts of Pu-238 in the plutonium of usual
   plutonium-producing reactors. However, isotopic separation would be
   quite expensive compared to another method: when an U-235 atom captures
   a neutron, it is converted to an excited state of U-236. Some of the
   excited U-236 nuclei undergo fission, but some decay to the ground
   state of U-236 by emitting gamma radiation. Further neutron capture
   creates U-237 which has a half-life of 7 days and thus quickly decays
   to Np-237. Since nearly all neptunium is produced in this way or
   consists of isotopes which decay quickly, one gets nearly pure Np-237
   by chemical separation of neptunium. After this chemical separation,
   Np-237 is again irradiated by reactor neutrons to be converted to
   Np-238 which decays to Pu-238 with a half-life of 2 days.

Compounds

   Plutonium reacts readily with oxygen, forming PuO and PuO[2], as well
   as intermediate oxides. It reacts with the halides, giving rise to
   compounds such as PuX[3] where X can be F, Cl, Br or I; PuF[4] and
   PuF[6] are also seen. The following oxyhalides are observed: PuOCl,
   PuOBr and PuOI. It will react with carbon to form PuC, nitrogen to form
   PuN and silicon to form PuSi[2].

   Plutonium like other actinides readily forms a dioxide plutonyl core
   (PuO[2]). In the environment, this plutonyl core readily complexes with
   carbonate as well as other oxygen moieties (OH^-, NO[2]^-, NO[3]^-, and
   SO[4]^-2) to form charged complexes which can be readily mobile with
   low affinities to soil.
     * PuO[2](CO[3])[1]^-2
     * PuO[2](CO[3])[2]^-4
     * PuO[2](CO[3])[3]^-6

   PuO[2] formed from neutralizing highly acidic nitric acid solutions
   tends to form polymeric PuO[2] which is resistant to complexation.
   Plutonium also readily shifts valences between the +3, +4, +5 and +6
   states. It is common for some fraction of plutonium in solution to
   exist in all of these states in equilibrium.
   Image showing colors of various oxidation states of Pu in solution on
   the left and colors of only one Pu oxidation state (IV) on the right in
   solutions containing different anions.
   Enlarge
   Image showing colors of various oxidation states of Pu in solution on
   the left and colors of only one Pu oxidation state (IV) on the right in
   solutions containing different anions.

Allotropes

   A diagram of the allotropes of plutonium at ambient pressure
   A diagram of the allotropes of plutonium at ambient pressure

   Even at ambient pressure, plutonium occurs in a variety of allotropes.
   These allotropes differ widely in crystal structure and density; the α
   and δ allotropes differ in density by more than 25% at constant
   pressure.

   The presence of these many allotropes makes machining plutonium very
   difficult, as it changes state very readily. The reasons for the
   complicated phase diagram are not entirely understood; recent research
   has focused on constructing accurate computer models of the phase
   transitions.

   In weapons applications, plutonium is often alloyed with another metal
   (e.g., delta phase with a small percentage of gallium) to increase
   phase stability and thereby enhance workability and ease of handling.
   Interestingly, in fission weapons, the explosive shock waves used to
   compress a plutonium core will also cause a transition from the usual
   delta phase plutonium to the denser alpha phase, significantly helping
   to achieve supercriticality.

Isotopes

   Twenty-one plutonium radioisotopes have been characterized. The most
   stable are Pu-244, with a half-life of 80.8 million years, Pu-242, with
   a half-life of 373,300 years, and Pu-239, with a half-life of 24,110
   years. All of the remaining radioactive isotopes have half-lives that
   are less than 7,000 years. This element also has eight meta states,
   though none are very stable (all have half-lives less than one second).

   The isotopes of plutonium range in atomic weight from 228.0387 u
   (Pu-228) to 247.074 u (Pu-247). The primary decay modes before the most
   stable isotope, Pu-244, are spontaneous fission and alpha emission; the
   primary mode after is beta emission. The primary decay products before
   Pu-244 are uranium and neptunium isotopes (neglecting the wide range of
   daughter nuclei created by fission processes), and the primary products
   after are americium isotopes.
   A pellet of plutonium-238, glowing under its own light, used for
   radioisotope thermoelectric generators.
   Enlarge
   A pellet of plutonium-238, glowing under its own light, used for
   radioisotope thermoelectric generators.

   Key isotopes for applications are Pu-239, which is suitable for use in
   nuclear weapons and nuclear reactors, and Pu-238, which is suitable for
   use in radioisotope thermoelectric generators; see above for more
   details. The isotope Pu-240 undergoes spontaneous fission very readily,
   and is produced when Pu-239 is exposed to neutrons. The presence of
   Pu-240 in a material limits its nuclear bomb potential since it emits
   neutrons randomly, increasing the difficulty of initiating accurately
   the chain reaction at the desired instant and thus reducing the bomb's
   reliability and power. Plutonium consisting of more than about 90%
   Pu-239 is called weapon-grade plutonium; plutonium obtained from
   commercial reactors generally contains at least 20% Pu-240 and is
   called reactor-grade plutonium.

   Pu-240, while of little importance by itself, plays a crucial role as a
   contaminant in plutonium used in nuclear weapons. It spontaneously
   fissions at a high rate, and as a 1% impurity in Pu-239 will lead to
   unacceptably early initiation of a fission chain reaction in gun-type
   atomic weapons, blowing the weapon apart before much of its material
   can fission. Pu-240 contamination is the reason plutonium weapons must
   use an implosion design. A theoretical 100% pure Pu-239 weapon could be
   constructed as a gun type device, but achieving this level of purity is
   prohibitively difficult. Pu-240 contamination has proven a mixed
   blessing to weapons designers. While it created delays and headaches
   during the Manhattan Project because of the need to develop implosion
   technology, those very same difficulties are currently a barrier to
   nuclear proliferation. Implosion devices are also inherently more
   efficient and less prone toward accidental detonation than are gun-type
   weapons.

Precautions

   All isotopes and compounds of plutonium are toxic and radioactive.
   While plutonium is sometimes described in media reports as "the most
   toxic substance known to man", from the standpoint of literal toxicity
   this is incorrect. As of 2006, there has yet to be a single human death
   officially attributed to exposure to plutonium itself (with the
   exception of plutonium-related criticality accidents).
   Naturally-occurring radium is about 200 times more radiotoxic than
   plutonium, and some organic toxins like botulin toxin are still more
   toxic. Botulin toxin, in particular, has a lethal dose of 300pg/kg, far
   less than the quantity of plutonium that poses a significant cancer
   risk. In addition, beta and gamma emitters (including the carbon-14 and
   potassium-40 in nearly all food) can cause cancer on casual contact,
   which alpha emitters cannot.

   When taken in by mouth, plutonium is less poisonous (except for risk of
   causing cancer) than several common substances including caffeine,
   acetaminophen, some vitamins, pseudoephedrine, and any number of plants
   and fungi. It is perhaps somewhat more poisonous than pure ethanol, but
   less so than tobacco; and many illegal drugs. From a purely chemical
   standpoint, it is about as poisonous as lead and other heavy metals.
   Not surprisingly, it has a metallic taste.
   Glowing hot bits of plutonium in a box, which have been set alight due
   to plutonium's pyrophoric nature.
   Enlarge
   Glowing hot bits of plutonium in a box, which have been set alight due
   to plutonium's pyrophoric nature.

   That said, there is no doubt that plutonium may be extremely dangerous
   when handled incorrectly. The alpha radiation it emits does not
   penetrate the skin, but can irradiate internal organs when plutonium is
   inhaled or ingested. Particularly at risk are the skeleton, where it is
   likely to be absorbed by the bone surface, and the liver, where it will
   likely collect and become concentrated. Approximately 0.008 microcuries
   absorbed in bone marrow is the maximum withstandable dose. Anything
   more is considered toxic. Extremely fine particles of plutonium (on the
   order of micrograms) can cause lung cancer if inhaled.

   Other substances including ricin, tetrodotoxin, botulinum toxin, and
   tetanus toxin are fatal in doses of (sometimes far) under one
   milligram, and others (the nerve agents, the amanita toxin) are in the
   range of a few milligrams. As such, plutonium is not unusual in terms
   of toxicity, even by inhalation. In addition, those substances are
   fatal in hours to days, whereas plutonium (and other cancer-causing
   radioactives) give an increased chance of illness decades in the
   future. Considerably larger amounts may cause acute radiation poisoning
   and death if ingested or inhaled; however, so far, no human is known to
   have immediately died because of inhaling or ingesting plutonium and
   many people have measurable amounts of plutonium in their bodies.

   It must be noted, however, that in contrast to naturally occurring
   radioisotopes such as radium or C-14, plutonium was manufactured,
   concentrated, and isolated in large amounts (hundreds of metric tons)
   during the Cold War for weapons production. These stockpiles, whether
   or not in weapons form, pose a significant problem because, unlike
   chemical or biological agents, no chemical process can destroy them.
   One proposal to dispose of surplus weapons-grade plutonium is to mix it
   with highly radioactive isotopes (e.g., spent reactor fuel) to deter
   handling by potential thieves or terrorists. Another is to mix it with
   uranium and use it to fuel nuclear power reactors (the mixed oxide or
   MOX approach). This would not only fission (and thereby destroy) much
   of the Pu-239, but also transmute a significant fraction of the
   remainder into Pu-240 and heavier isotopes that would make the
   resulting mixture useless for nuclear weapons.

   Toxicity issues aside, care must be taken to avoid the accumulation of
   amounts of plutonium which approach critical mass, particularly because
   plutonium's critical mass is only a third of that of uranium-235's.
   Despite not being confined by external pressure as is required for a
   nuclear weapon, it will nevertheless heat itself and break whatever
   confining environment it is in. Shape is relevant; compact shapes such
   as spheres are to be avoided. Plutonium in solution is more likely to
   form a critical mass than the solid form (due to moderation by the
   hydrogen in water). A weapon-scale nuclear explosion cannot occur
   accidentally, since it requires a greatly supercritical mass in order
   to explode rather than simply melt or fragment. However, a marginally
   critical mass will cause a lethal dose of radiation and has in fact
   done so in the past on several occasions.

   Criticality accidents have occurred in the past, some of them with
   lethal consequences. Careless handling of tungsten carbide bricks
   around a 6.2 kg plutonium sphere resulted in a lethal dose of radiation
   at Los Alamos on August 21, 1945, when scientist Harry K. Daghlian, Jr.
   received a dose estimated to be 510 rems (5.1 Sv) and died four weeks
   later. Nine months later, another Los Alamos scientist, Louis Slotin,
   died from a similar accident involving a beryllium reflector and the
   exact same plutonium core (the so-called "demon core") that had
   previously claimed the life of Daghlian. These incidents were
   fictionalized in the 1989 film Fat Man and Little Boy. In 1958, during
   a process of purifying plutonium at Los Alamos, a critical mass was
   formed in a mixing vessel, which resulted in the death of a crane
   operator. Other accidents of this sort have occurred in the Soviet
   Union, Japan, and many other countries. (See List of nuclear
   accidents.) The 1986 Chernobyl accident caused a major release of
   plutonium.

   Metallic plutonium is also a fire hazard, especially if the material is
   finely divided. It reacts chemically with oxygen and water which may
   result in an accumulation of plutonium hydride, a pyrophoric substance;
   that is, a material that will ignite in air at room temperature.
   Plutonium expands considerably in size as it oxidizes and thus may
   break its container. The radioactivity of the burning material is an
   additional hazard. Magnesium oxide sand is the most effective material
   for extinguishing a plutonium fire. It cools the burning material,
   acting as a heat sink, and also blocks off oxygen. Water is also
   effective. There was a major plutonium-initiated fire at the Rocky
   Flats Plant near Boulder, Colorado in 1969. To avoid these problems,
   special precautions are necessary to store or handle plutonium in any
   form; generally a dry inert atmosphere is required.

Plutonium in fiction

   Plutonium was the power source for the De Lorean time machine in Back
   to the Future creating 1.21 " jigowatts" of electricity for temporal
   displacement.

   Marvin the Martian used Pu-239 space modulator in the Looney Tunes
   cartoons.

   The discovery of an impossible isotope, ^186Pu, is the starting point
   for the plot of Isaac Asimov's science fiction novel, The Gods
   Themselves.

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