U.S. Code of Federal Regulations

Regulations most recently checked for updates: Feb 01, 2023

§ 50-204.24 - Caution signs, labels, and signals.

(a) General. (1) Symbols prescribed by this section shall use the conventional radiation caution colors (magenta or purple on yellow background). The symbol prescribed by this section is the conventional three-bladed design:

Radiation Symbol

1. Cross-hatched area is to be magenta or purple.

2. Background is to be yellow.

(2) In addition to the contents of signs and labels prescribed in this section, employers may provide on or near such signs and labels any additional information which may be appropriate in aiding individuals to minimize exposure to radiation or to radioactive material.

(b) Radiation areas. Each radiation area shall be conspicuously posted with a sign or signs bearing the radiation caution symbol and the words:

Caution 2

2 Or “Danger”.

Radiation Area

(c) High radiation area. (1) Each high radiation area shall be conspicuously posted with a sign or signs bearing the radiation caution symbol and the words:

Caution 2 High Radiation Area

(2) Each high radiation area shall be equipped with a control device which shall either cause the level of radiation to be reduced below that at which an individual might receive a dose of 100 millirems in 1 hour upon entry into the area or shall energize a conspicuous visible or audible alarm signal in such a manner that the individual entering and the employer or a supervisor of the activity are made aware of the entry. In the case of a high radiation area established for a period of 30 days or less, such control device is not required.

(d) Airborne radioactivity area. (1) As used in the provisions of this subpart, “airborne radioactivity area” means (i) any room, enclosure, or operating area in which airborne radioactive materials, composed wholly or partly of radioactive material, exist in concentrations in excess of the amounts specified in column 1 of Table 1 of appendix B to 10 CFR part 20 or (ii) any room, enclosure, or operating area in which airborne radioactive materials exist in concentrations which, averaged over the number of hours in any week during which individuals are in the area, exceed 25 percent of the amounts specified in column 1 of the described Table 1.

(2) Each airborne radioactivity area shall be conspicuously posted with a sign or signs bearing the radiation caution symbol and the words:

Caution 2 Airborne Radioactivity Area

(e) Additional requirements. (1) Each area or room in which radioactive material is used or stored and which contains any radioactive material (other than natural uranium or thorium) in any amount exceeding 10 times the quantity of such material specified in appendix C to 10 CFR part 20 shall be conspiciously posted with a sign or signs bearing the radiation caution symbol and the words:

Caution 2 Radioactive Materials

(2) Each area or room in which natural uranium or thorium is used or stored in an amount exceeding 100 times the quantity specified in appendix C to 10 CFR part 20 shall be conspicuously posted with a sign or signs bearing the radiation caution symbol and the words:

Caution 2 Radioactive Materials

(f) Containers. (1) Each container in which is transported, stored, or used a quantity of any radioactive material (other than natural uranium or thorium) greater than the quantity of such material specified in appendix C to 10 CFR part 20 shall bear a durable, clearly visible label bearing the radiation caution symbol and the words:

Caution 2 Radioactive Materials

(2) Each container in which natural uranium or thorium is transported, stored, or used in a quantity greater than 10 times the quantity specified in appendix C to 10 CFR part 20 shall bear a durable, clearly visible label bearing the radiation caution symbol and the words:

Caution 2

2 Or “Danger”.

Radioactive Materials

(3) Notwithstanding the provisions of paragraphs (f) (1) and (2) of this section a label shall not be required:

(i) If the concentration of the material in the container does not exceed that specified in column 2 of the described Table 1, or

(ii) For laboratory containers, such as beakers, flasks, and tests tubes, used transiently in laboratory procedures, when the user is present.

(4) Where containers are used for storage, the labels required in this paragraph shall state also the quantities and kinds of radioactive materials in the containers and the date of measurement of the quantities.