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There is a significant difference in quantifying the exposure due to internal
radioactive contamination, i.e. caused by the emission of radiation from radioactive
material which entered the human body through inhalation or ingestion, and exposure by radionuclides on the surface of the body, which may also be considered as a
special case of radioactive contamination. The situation is schematically demonstrated in Fig. 19 (Sabol and Šesták 2017). Here the initial quantity is the activity
(A) corresponding to the number of disintegrations which take place in a radionuclide per second. The basic unit here is s
−1
, which has the special name Bq
(Becquerel). The committed quantities based on the internal dose resulting from
inhaling, ingesting or injecting radioactive materials are referred to as committed
quantities. The integration time (commitment) in years following the intake τ is
taken to be 50 years for adults and 70 years for children.
Considering the range of the radiation, it is obvious that external exposure is
practically excluded for alpha particles and it is of marginal significance for lowenergy beta particles. The main means of protection against external radiation is
shielding, distance and time. It is worth noting that in the case of photons or neutrons (indirectly ionizing radiation), shielding cannot fully stop them but only
reduce their number by attenuation.
As to the internal exposure, however, any radiation emitted by radioactive materials which enters the body can contribute to the absorbed dose inside the body.
Once inside, radiation energy is deposited in cells, tissues and organs. The extent of
Fig. 19 Quantities characterizing personal exposure from the intake of radioactive material or
from skin contamination
Uranium in the Beginning of the Nuclear Age: Reflections on the Historical Role…
There is a significant difference in quantifying the exposure due to internal
radioactive contamination, i.e. caused by the emission of radiation from radioactive
material which entered the human body through inhalation or ingestion, and exposure by radionuclides on the surface of the body, which may also be considered as a
special case of radioactive contamination. The situation is schematically demonstrated in Fig. 19 (Sabol and Šesták 2017). Here the initial quantity is the activity
(A) corresponding to the number of disintegrations which take place in a radionuclide per second. The basic unit here is s
−1
, which has the special name Bq
(Becquerel). The committed quantities based on the internal dose resulting from
inhaling, ingesting or injecting radioactive materials are referred to as committed
quantities. The integration time (commitment) in years following the intake τ is
taken to be 50 years for adults and 70 years for children.
Considering the range of the radiation, it is obvious that external exposure is
practically excluded for alpha particles and it is of marginal significance for lowenergy beta particles. The main means of protection against external radiation is
shielding, distance and time. It is worth noting that in the case of photons or neutrons (indirectly ionizing radiation), shielding cannot fully stop them but only
reduce their number by attenuation.
As to the internal exposure, however, any radiation emitted by radioactive materials which enters the body can contribute to the absorbed dose inside the body.
Once inside, radiation energy is deposited in cells, tissues and organs. The extent of
Fig. 19 Quantities characterizing personal exposure from the intake of radioactive material or
from skin contamination
Uranium in the Beginning of the Nuclear Age: Reflections on the Historical Role…