Page 86 - 6880

few or no visible symptoms around the time of exposure may cause problems later
on.
A person who is exposed to 3,000 rads will experience nausea and vomiting,
and they may experience confusion and a loss of consciousness within a few hours.
Tremors and convulsions will occur 5 to 6 hours after exposure. Within 3 days,
there will be coma and death.
People who experience repeated doses, or who appear to recover, may have
long-term effects.
Dose limits of radiation can be one-time (in the first 4 days) and multiple
(over 4 days) and depend on the amount of radiation and the time during which this
dose is obtained.
Permissible doses:
- disposable or within 4 days - 50 R;
- within 30 days (month) - 100 R;
- within 90 days (quarter) - 200 R;
- during the year - 300 R.
The dose limits for radiation workers are:
 in any period of 5 years, an average effective dose of 20 millisieverts

per year;
 in a period of 12 months, an effective dose of 50 millisieverts;
 in any period of less than 12 months but not less than 1 month, an
effective dose of the amount which is the product of 50 millisieverts and the ratio
of that period in weeks to 52 weeks;
 in any period of less than 1 month, an effective dose of 1/12 of 50
millisieverts.
The dose limits for persons other than radiation workers are:
 in any period of 5 years, an average effective dose of 1 millisievert per
year;
 in any period of 12 months, an effective dose of 5 millisieverts;
 in respect of an area which such persons might continuously occupy –
an effective dose of 20 microsieverts in any 1 hour; and − an effective dose of 250
microsieverts in any period of 7 days.
One sievert is a large dose. The average annual dose of 0.05 Sv (50 mSv).
The effects of being exposed to large doses of radiation at one time (acute
exposure) vary with the dose. Here are some examples:
10 Sv - Risk of death within days or weeks;
1 Sv - Risk of cancer later in life (5 in 100);
100 mSv - Risk of cancer later in life (5 in 1000);
50 mSv - for annual dose for radiation workers in any one year;
20 mSv - for annual average dose, averaged over five years.
Radiation sickness can be acute, happening soon after exposure, or chronic,
where symptoms appear over time or after some time, possibly years later.

86