Taking advantage of all available means to limit radiation exposure
is always recommended. The three methods of limiting exposure
are:
TIME
DISTANCE
SHIELDING
These methods are a part of an
ALARA
(As Low As Reasonably
Achievable) program.
Time
The simplest way to reduce exposure is to keep the time spent
around a radioactive source to a minimum. If time is cut in half, so
is the exposure, with 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–3). Doubling the distance from
a radiation source reduces the exposure to one-fourth its original
value. If the distance is tripled, the exposure is reduced by a factor
of nine, and so on
Figure A–3. Effect of Distance on Exposure
Appendix A–6
Summary of Contents for 4640-B
Page 6: ...NOTES vi...
Page 12: ...NOTES xii...
Page 17: ...1 GENERAL INFORMATION Figure 1 1 Model 4640 B Parts and Accessories Model 4640 B 1 5...
Page 22: ...NOTES 1 10...
Page 26: ...NOTES 2 4...
Page 84: ...NOTES Appendix A 12...
Page 108: ...NOTES Appendix C 18...
Page 130: ...NOTES Appendix F 8...
