Calculation of Radiation Safety Margins
“Phe numerous nuclear tests conducted
have nade tt possible to define unanimously recopnized security standards.
Atmospheric nuclear explosions, like underground nuclear explosions that are not entirely
contained, actually release numerousfission products into the atmosphere that can be harmful to the
human body. These products emit rays or particles which, by releasing their energy in living tissues,
can cause changes in their structure or organic disturbances.
The human body fights all types of aggression against it by its spontaneous regenerative
capacity. Thus it struggics against strong sudden radiation or weak continual radiation.
The many research projects carried out the world over have made it possible to evaluate
quantitatively the risk resulting from radiation.
Theeffect of radiation depends on the length of exposure and theintensity. If strong
radiation is expcrienced for a few hours over the entire human body:
:
e A dose of 25 rems causes no apparent elfect.
© A dose of 75 rems marks the appcarance ofthe first organic signs, especially
changes in blood composition accompanied by fatigue and nausea.
e A dose of 200 rems marks the beginning of the acute radiation syndrome. |
e A dose of 400 remsis the average lethal dose for man.'
The global natural radioactivity to which man is exposed ranges from 0.2 rem/year
on the average in chalky soil regions to several rems/year in especially tadioactive regionsof the globe, and the health of the inhabitants normally living there has never
been altered.
7
,
Rays from artificial radioactivity originate mainlyfrom medical radiation (from 0.05
to 0.02 rem/year). |
4
World-scale fallout produced by all the nuclear tests conducted since 1945 (more
than 500 experiments) stands at an average level of less than 0.01 rem/year.
Thelevel of radioactivity due to those tests is equal to that experienced by an individual whohad beenliving on the coast and movedfor onc year to an altitude of 1,500
feet. (Increase in radioactivity as a result of cosmic rays alone which tises 50% with
a change of 3,000feet in altitude. )-