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12 Health Hazards and Protection
Contamination of the apparatus is due to either physical adsorption, which can
be washed off by any wetting agent, or chemisorption, which is due to the residual
valency on the surface of the container and needs special techniques for decontamination. A universal decontaminating solution is the stable isotope of the radioactive
isotope. But the chemical nature of the stable isotope should be the same as that of
the radioactive isotope. For example, apparatus contaminated with
82 Br can be easily
decontaminated by washing the apparatus with 0.1M NaBr solution. But decontamination will not be to the satisfaction if the apparatus, in this case, is washed with
0.1M aqueous solution of bromine, because the radioactive isotope is present as
bromide ion. This method is known as the isotope dilution technique, where the
radioactive isotope gets diluted with the stable isotopes and thus its level of activity
get reduced tremendously by washings; two to three times with the stable isotope
solution. Such dilution can occur only if both, the radioactive isotope and the stable
isotope are present in the same chemical form. Some times, some special decontaminating agents are used for this purpose. In such cases, the decontaminating agent
must have a good wetting action and should have a greater preference for the absorption than the radioactive material on the surface concerned. The decontaminating
reagents should not spoil the smoothness of the surface of the container, because
it will make the decontamination very difficult e.g., sodium hydroxide or chromic
acid. The reagents which form soluble complexes with the radioactive material are
also preferred in some special cases, for example, ethylene-diamine-tetraacetic acid
(E.D.T.A). Detail procedures for the decontamination of the apparatus are discussed
in the following sections.
12.9.1 Process of Decontamination
It is customary to wash the apparatus with a carrier solution which dilutes the activity
to a considerable extent. The carrier solution is the aqueous solution of the stable
isotope of a radioactive isotope, which is to be decontaminated. The chemical nature
of both of them should be in the same form. In addition, dilute acids, such as nitric
acid, inhibited orthophosphoric acid may also be tried. The complexing agents such
as EDTA or any suitable ion-exchange resins may perhaps be useful for this purpose.
Hands can usually be decontaminated by washing with soap and water. Sometimes
titanium dioxide paste or EDTA solutions are useful. A good general decontamination agent is a saturated potassium permanganate solution, followed by 5% sodium
bisulphite solution. But chemical washings should not be employed regularly, since
the skin being porous may lead to penetration of the activity into the body and thus
it may cause an internal hazard. In the case of internal contamination due to any cuts
etc., bleeding should be encouraged and proper medical attention should be given.
Bleeding helps in eliminating the radioactive nuclide.
12 Health Hazards and Protection
Contamination of the apparatus is due to either physical adsorption, which can
be washed off by any wetting agent, or chemisorption, which is due to the residual
valency on the surface of the container and needs special techniques for decontamination. A universal decontaminating solution is the stable isotope of the radioactive
isotope. But the chemical nature of the stable isotope should be the same as that of
the radioactive isotope. For example, apparatus contaminated with
82 Br can be easily
decontaminated by washing the apparatus with 0.1M NaBr solution. But decontamination will not be to the satisfaction if the apparatus, in this case, is washed with
0.1M aqueous solution of bromine, because the radioactive isotope is present as
bromide ion. This method is known as the isotope dilution technique, where the
radioactive isotope gets diluted with the stable isotopes and thus its level of activity
get reduced tremendously by washings; two to three times with the stable isotope
solution. Such dilution can occur only if both, the radioactive isotope and the stable
isotope are present in the same chemical form. Some times, some special decontaminating agents are used for this purpose. In such cases, the decontaminating agent
must have a good wetting action and should have a greater preference for the absorption than the radioactive material on the surface concerned. The decontaminating
reagents should not spoil the smoothness of the surface of the container, because
it will make the decontamination very difficult e.g., sodium hydroxide or chromic
acid. The reagents which form soluble complexes with the radioactive material are
also preferred in some special cases, for example, ethylene-diamine-tetraacetic acid
(E.D.T.A). Detail procedures for the decontamination of the apparatus are discussed
in the following sections.
12.9.1 Process of Decontamination
It is customary to wash the apparatus with a carrier solution which dilutes the activity
to a considerable extent. The carrier solution is the aqueous solution of the stable
isotope of a radioactive isotope, which is to be decontaminated. The chemical nature
of both of them should be in the same form. In addition, dilute acids, such as nitric
acid, inhibited orthophosphoric acid may also be tried. The complexing agents such
as EDTA or any suitable ion-exchange resins may perhaps be useful for this purpose.
Hands can usually be decontaminated by washing with soap and water. Sometimes
titanium dioxide paste or EDTA solutions are useful. A good general decontamination agent is a saturated potassium permanganate solution, followed by 5% sodium
bisulphite solution. But chemical washings should not be employed regularly, since
the skin being porous may lead to penetration of the activity into the body and thus
it may cause an internal hazard. In the case of internal contamination due to any cuts
etc., bleeding should be encouraged and proper medical attention should be given.
Bleeding helps in eliminating the radioactive nuclide.