Future Radiation Levels (FEMA)
Future radiation levels can be predicted [exposure] by a combination of radiation levels [rates/hr] as measured with or without shielding and time intervals [hours].
A FEMA website offers the following rough thumb rule regarding radiation levels and time: The 7:10 Rule of Thumb states that for every 7-fold increase in time after detonation, there is a 10-fold decrease in the exposure rate:
In other words, when the amount of time is multiplied by 7, the exposure rate is divided by 10. [2 hours after detonation the exposure rate is 400 R/hr. After 14 hours, the exposure rate will be 1/10 as much, or 40 R/hr.]
The exposure rate must be expressed in the same unit as the time increase. For example, if the time increase is expressed in hours,
A FEMA website offers the following rough thumb rule regarding radiation levels and time: The 7:10 Rule of Thumb states that for every 7-fold increase in time after detonation, there is a 10-fold decrease in the exposure rate:
In other words, when the amount of time is multiplied by 7, the exposure rate is divided by 10. [2 hours after detonation the exposure rate is 400 R/hr. After 14 hours, the exposure rate will be 1/10 as much, or 40 R/hr.]
The exposure rate must be expressed in the same unit as the time increase. For example, if the time increase is expressed in hours,