29
In radon dosimetry another quantity called working level (WL) is still widely
used. The unit WL was introduced in early days of radon (
222
Ra) and radon progeny
(primarily
218
Po and
214
Po) assessment and monitoring. Working level is a historical
unit of concentration of uranium mining products of radon. One WL refers to the
concentration of short-lived decay products of radon in equilibrium with 3700 Bq/
m
3
in air. By definition, 1 WL equals any combination of radon decay products
which release potential alpha energy of 1.3 × 10
5
MeV in complete decay. In order
to express the total exposure of a person, another unit is traditionally used, the working level month (WLM). This unit is equivalent to the exposure to radon progeny
corresponding to the product of the progeny concentration in WL and the exposure
time in nominal months. Inhalation of air with a concentration of 1 WL of radon
daughters for 170 working hours results in an exposure of 1 WLM. An exposure of
1 WLM results in a dose from alpha particles to the lung of about 12 mGy to the
critical target cells in the lung.
Several epidemiological studies to assess radon-related exposure have been organized. Many of these investigations took place in the former Czechoslovakia and
later in the Czech Republic (Ševc et al. 1976; Horáček et al. 1977; Tomášek et al.
1994; Ševc et al. 1998; Tomášek et al. 2008; Tomášek 2012). One of those studies
(Tomášek 2012) was based on 9978 Czech uranium miners with 1141 lung cancer
deaths, and an updated follow-up 1952–2010 and corresponding to 31 years of
mean follow-up was observed. These results were used to obtain more reliable estimation of the exposure–response relationship. The study was based on the investigation of a total of 9978 miners exposed in two different periods. The results are
summarized in Fig. 23.
5 Conclusion
Uranium has played an important role in mankind’s history. There have been a number of applications of this element and its numerous compounds and decay products
in industry, medicine, science and many other areas. The most important use of the
enriched uranium is in the production of energy by its fission. Unfortunately, uranium can also be used in weapons of mass destruction, which still present a potential threat to the planet.
Since radioactivity as well as the discovery of radium and polonium was made
while experimenting with uranium ore from Jáchymov, this small town entered forever into the history of the modern nuclear age. Uranium from its deposits was also
used for the Soviet Union’s military industry which succeeded to follow the USA in
producing nuclear bombs.
In earlier times, perhaps until the 1970s, uranium mining, milling and other
aspects of the uranium fuel cycle were not considered a big environmental problem, and, in addition, the international standards and national legislations for ensuring adequate protection of workers and the public had not been so strict as they
are nowadays. This is why it is necessary to deal with the uranium legacy and to
Uranium in the Beginning of the Nuclear Age: Reflections on the Historical Role…
In radon dosimetry another quantity called working level (WL) is still widely
used. The unit WL was introduced in early days of radon (
222
Ra) and radon progeny
(primarily
218
Po and
214
Po) assessment and monitoring. Working level is a historical
unit of concentration of uranium mining products of radon. One WL refers to the
concentration of short-lived decay products of radon in equilibrium with 3700 Bq/
m
3
in air. By definition, 1 WL equals any combination of radon decay products
which release potential alpha energy of 1.3 × 10
5
MeV in complete decay. In order
to express the total exposure of a person, another unit is traditionally used, the working level month (WLM). This unit is equivalent to the exposure to radon progeny
corresponding to the product of the progeny concentration in WL and the exposure
time in nominal months. Inhalation of air with a concentration of 1 WL of radon
daughters for 170 working hours results in an exposure of 1 WLM. An exposure of
1 WLM results in a dose from alpha particles to the lung of about 12 mGy to the
critical target cells in the lung.
Several epidemiological studies to assess radon-related exposure have been organized. Many of these investigations took place in the former Czechoslovakia and
later in the Czech Republic (Ševc et al. 1976; Horáček et al. 1977; Tomášek et al.
1994; Ševc et al. 1998; Tomášek et al. 2008; Tomášek 2012). One of those studies
(Tomášek 2012) was based on 9978 Czech uranium miners with 1141 lung cancer
deaths, and an updated follow-up 1952–2010 and corresponding to 31 years of
mean follow-up was observed. These results were used to obtain more reliable estimation of the exposure–response relationship. The study was based on the investigation of a total of 9978 miners exposed in two different periods. The results are
summarized in Fig. 23.
5 Conclusion
Uranium has played an important role in mankind’s history. There have been a number of applications of this element and its numerous compounds and decay products
in industry, medicine, science and many other areas. The most important use of the
enriched uranium is in the production of energy by its fission. Unfortunately, uranium can also be used in weapons of mass destruction, which still present a potential threat to the planet.
Since radioactivity as well as the discovery of radium and polonium was made
while experimenting with uranium ore from Jáchymov, this small town entered forever into the history of the modern nuclear age. Uranium from its deposits was also
used for the Soviet Union’s military industry which succeeded to follow the USA in
producing nuclear bombs.
In earlier times, perhaps until the 1970s, uranium mining, milling and other
aspects of the uranium fuel cycle were not considered a big environmental problem, and, in addition, the international standards and national legislations for ensuring adequate protection of workers and the public had not been so strict as they
are nowadays. This is why it is necessary to deal with the uranium legacy and to
Uranium in the Beginning of the Nuclear Age: Reflections on the Historical Role…