16.1 Introduction
Plutonium as an element refers to the group of transuranic elements (TUE), which is
a group of radioactive substances almost completely of man–made origin. In nature,
the TUE (particularly, plutonium and neptunium) were found in the earth’s crust in
trace amounts in uranium minerals. Plutonium is formed by the spontaneous fission
of uranium nuclei under the influence of neutrons of cosmic radiation (Transuranic
elements 1985; Plutonium 2003). With neutron activation of uranium fuel in
reactors formed of alpha–emitting radionuclides plutonium
238 Pu,
239 Pu,
240
Pu
and in smaller quantities – nuclides of heavier isotopes and elements. Currently,
it is known about 20 plutonium isotopes with the mass numbers of 228–247. Among
them 15 isotopes are alpha–emitters and only five isotopes (mass numbers 241, 243
and 245–247) are beta–emitters. In the thermonuclear explosions produced all the
plutonium isotopes, up to
257 Pu. But their life–time is tenths of a second, and
explore the many short-lived isotopes of plutonium have not yet succeeded (Plutonium 2003; Morss et al. 2008).
16.1.1 Nature and Man-Made Plutonium
The plutonium volatility is low, but still its small number is coming into the
environment from emissions during operation of nuclear facilities (Warner and
Harrison 1993). The most important industrial and radioecological radioisotope is
239 Pu. Its reserves of natural origin in the biosphere at a maximum was estimated at
several tens of kilograms (about 50 kg) and the anthropogenic plutonium stocks at
the end of the twentieth century, reached 950 tons, including 650 tons already
attained in nuclear reactors and approximately 300 tons produced for military
purposes (Sources and effects 1996; Plutonium 2003) Current stocks of the
man-made plutonium are estimated at 2000 tons.
The majority of plutonium is contained in the isolated from the environment.
These are potential sources of environmental contamination, which pose a serious,
unresolved problem (Warner and Harrison 1993). One potential source of environmental contamination with TUE radionuclides (including plutonium) is the disposal
of radioactive waste, such as dumping it in the sea and oceans. Although the
performed monitoring studies indicate that currently environmental releases of
radioactive substances are insignificant in locations of dumping, it must be remembered that a large amount of radioactive products is concentrated in these areas
(WOMARS 2005).
A certain part of the technogenic plutonium (more than 10 tons) dispersed
around the globe as a result of its admission into the environment from various
anthropogenic sources (Plutonium 2003). Secondary sources of radioactive long–
lived isotopes make their contribution to the contamination of the environment by
TUE. The secondary sources of contamination of abiogenic and biogenic
248
N.N. Tereshchenko
Plutonium as an element refers to the group of transuranic elements (TUE), which is
a group of radioactive substances almost completely of man–made origin. In nature,
the TUE (particularly, plutonium and neptunium) were found in the earth’s crust in
trace amounts in uranium minerals. Plutonium is formed by the spontaneous fission
of uranium nuclei under the influence of neutrons of cosmic radiation (Transuranic
elements 1985; Plutonium 2003). With neutron activation of uranium fuel in
reactors formed of alpha–emitting radionuclides plutonium
238 Pu,
239 Pu,
240
Pu
and in smaller quantities – nuclides of heavier isotopes and elements. Currently,
it is known about 20 plutonium isotopes with the mass numbers of 228–247. Among
them 15 isotopes are alpha–emitters and only five isotopes (mass numbers 241, 243
and 245–247) are beta–emitters. In the thermonuclear explosions produced all the
plutonium isotopes, up to
257 Pu. But their life–time is tenths of a second, and
explore the many short-lived isotopes of plutonium have not yet succeeded (Plutonium 2003; Morss et al. 2008).
16.1.1 Nature and Man-Made Plutonium
The plutonium volatility is low, but still its small number is coming into the
environment from emissions during operation of nuclear facilities (Warner and
Harrison 1993). The most important industrial and radioecological radioisotope is
239 Pu. Its reserves of natural origin in the biosphere at a maximum was estimated at
several tens of kilograms (about 50 kg) and the anthropogenic plutonium stocks at
the end of the twentieth century, reached 950 tons, including 650 tons already
attained in nuclear reactors and approximately 300 tons produced for military
purposes (Sources and effects 1996; Plutonium 2003) Current stocks of the
man-made plutonium are estimated at 2000 tons.
The majority of plutonium is contained in the isolated from the environment.
These are potential sources of environmental contamination, which pose a serious,
unresolved problem (Warner and Harrison 1993). One potential source of environmental contamination with TUE radionuclides (including plutonium) is the disposal
of radioactive waste, such as dumping it in the sea and oceans. Although the
performed monitoring studies indicate that currently environmental releases of
radioactive substances are insignificant in locations of dumping, it must be remembered that a large amount of radioactive products is concentrated in these areas
(WOMARS 2005).
A certain part of the technogenic plutonium (more than 10 tons) dispersed
around the globe as a result of its admission into the environment from various
anthropogenic sources (Plutonium 2003). Secondary sources of radioactive long–
lived isotopes make their contribution to the contamination of the environment by
TUE. The secondary sources of contamination of abiogenic and biogenic
248
N.N. Tereshchenko