Search Fred Hutch Extranet

All areas and equipment in which radioactive material is stored and used may be posted (labeled) with a sign reading Caution - Radioactive Material that includes the conventional three-blade radiation symbol (trefoil). The blades of the symbol must be magenta, black or purple on a yellow background.

the radiation symbol
Figure IV.1: The Radiation Symbol (Trefoil)

Signs are posted at each entrance to an area where radioactive material is used or stored in accordance with WAC 246-221-120 and 130. Any equipment or container used for temporary or long-term handling or storage of radioactive material may also be required to be labeled with the Caution - Radioactive Material label.

8.1 Meanings of Radiation Signs

Caution - Radioactive Material: This sign informs staff that radioactive material is present. It does not give any information regarding the dose rate or actual amount of radioactive materials present in the area.

Caution - Radiation Area: This warning sign means the dose rate within this area is from 5 to 100 mrem in one hour. Radiation workers should not stay in these areas for more than four hours per day. The dose rate in the area will be monitored by EH&S.

Caution - High Radiation Area: This warning means the dose rate within this area is greater than 100 mrem in one hour. A radiation worker should not stay in the area more than one hour per week. The dose rate in the area will be monitored and posted by EH&S.

8.2 Posted Dose Rates

When there is enough radioactive material in an area to cause a likely dose rate to the whole body in excess of 5 mrem in one hour, the dose rate will be measured by EH&S. The area will be evaluated for additional measures for dose control. The chart below may be posted by the entrance to the room to explain what precautions must be taken while working in the area. In addition, shielding or stay time restrictions can be used to lower doses in these areas.

Table 8.2.1: Guidelines to Use When Working in an Area with a Posted Dose Rate

Reason or Dose Rates

Required Sign

Recommended Action To Be Taken

Radioactive Material

Caution-Radioactive Material

Be cognizant of potential radiation hazards. Check possibly contaminated items for contamination.

Small dose rates may occur in some areas within a lab, usually next to waste or some experiments. Do not linger near these areas.

5 to 50 mrem in one hour

Caution-Radiation Area

Do not stay in area for more than four hours per day.

50 to 100 mrem in one hour

Caution-Radiation Area

Do not stay in area more than one hour per day.

>100 mrem in one hour

Caution-High Radiation Area

Notify EH&S or your supervisor before entering and after leaving the area. Stay times will be developed by EH&S for entering actual high-radiation areas. Must have additional controls set by RSO prior to entering.

Loose Contamination > 200 cpm but less than 20,000 cpm

Contamination Area or Equipment

See Section 15.5

Fixed Contamination > 200 cpm

Fixed Contamination

See Section 12.2.10