Troxler 3430 Plus, Manual Of Operation And Instruction

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Appendix A–6
LIMITING EXPOSURE
Under average conditions, an individual working with the gauge
will receive less than 200 millirem per year.
A basic principle of radiation protection is that radiation exposure
should be kept as far below the limits as is reasonably achievable.
This is known as the
ALARA (as low as reasonable achievable)
principle. The three methods for limiting exposure are:
Time
Distance
Shielding
Time
The simplest way to reduce exposure is to minimize the time spent
around a radioactive source. If the time spent near a source is cut in
half, then the exposure is halved, all other factors remaining
constant.
Distance
Distance is another effective means to reduce radiation exposure. A
formula known as the
inverse square law relates the radiation
exposure rate to distance (Figure A–2). Doubling the distance from
a radiation source reduces the exposure to one-fourth its original
value. If the distance is tripled, then the exposure is reduced by a
factor of nine, and so on.