The values of WTfrom the 10CFR20 are given in Table 14.5.
Effective dose equivalent (HE) is the sum of the products of the committed
dose equivalent to each of the body organs and tissues when the total
body is irradiated uniformly and the weighting factor of the correspond-
ing organ or tissue (HE=ΣWT·HT,50).
Annual limit on intake(ALI) is the derived limit on the amount of radioac-
tive material allowed to be taken into the body of an adult worker by
inhalation or ingestion in a year. These values are given in 10CFR20
(Table 1, Appendix B).
Total effective dose equivalent (TEDE) is the sum of the deep-dose
equivalent (for external exposure) and the committed effective dose
equivalent (for internal exposure). It is the effective dose defined by Eq.
(14.25).
Restricted area is an area where an individual could receive in excess of
5 mrem (0.05 mSv) per hour at 30 cm from a radiation source.
High-radiation areais an area where an individual could receive from a
radiation source a dose equivalent in excess of 100 mrem (1 mSv) in 1 hr
at 30 cm from the source.
Very high-radiation areais an area where an individual could receive from
radiation sources an absorbed dose in excess of 500 rad (5 Gy) in 1 hr at
1 m from the source.
Unrestricted areais an area in which an individual could receive from an
external source a dose of 2 mrem (20mSv)/hr and 50 mrem (0.5 mSv)/yr.
Caution Signs and Labels
The NRC requires that specific signs, symbols, and labels be used to warn
people of possible danger from the presence of radiation. These signs use
magenta, purple, or black color on yellow background; some typical signs
are shown in Figure 16.1.
Caution: Radiation Area.This sign must be posted in radiation areas.
Caution: High Radiation Areaor Danger: High-Radiation Area.This sign
must be posted in high-radiation areas.
Caution: Radioactive Material or Danger: Radioactive material. This sign is
posted in areas or rooms in which 10 times the quantity of any licensed
material specified in Appendix C of 10CFR20 are used or stored. All con-
tainers with quantities of licensed materials exceeding those specified in
Appendix C of 10CFR20 should be labeled with this sign. These labels
must be removed or defaced before disposal of the container in the unre-
stricted areas.
Caution signs are not required in rooms storing the sealed sources, pro-
vided the radiation exposure at 1 foot (30 cm) from the surface of the source
reads less than 5 mrem (50mSv)/hr. Caution signs are not needed in rooms
272 16. Radiation Regulations and Protection