What distinguishes a Locked High Radiation Area from a High Radiation Area?

• A. It is open to the public
• B. It is an area with dose rate over 500 mrem
• C. It is a High Radiation Area with posted signage
• D. It has a dose rate exceeding 1000 mrem at 30 cm and is kept locked to prevent inadvertent exposure

Answer: (D)

A Locked High Radiation Area is a High Radiation Area that is physically locked to prevent inadvertent entry when the radiation level is very high. The important part is that it combines a very high dose rate with restricted access. In this context, a dose rate exceeding 1000 mrem per hour at a distance of 30 cm signals a level of exposure where safeguards are intensified, and locking the area helps ensure that only authorized, trained personnel can enter with the proper procedures and protection in place. This combination—high dose rate and secured access—is what sets a Locked High Radiation Area apart from a regular High Radiation Area, which might be posted or monitored but not locked. Opening the area to the public would defeat the protective purpose, while a higher dose rate or signage alone does not by itself create the locked status.