How does the 7:10 rule of thumb actually work?
In: Mathematics
Are you talking about the rule of thumb for nuclear radiation exposure?
If so, it lets you estimate how much exposure there will be in the future if you know the current exposure rate and how long since the explosion. Multiply however long it’s been since the explosion by 7 and you can divide exposure by 10.
>**The 7:10 Rule of Thumb**
>From the exposure rate determined by a survey instrument, future exposure rates may be predicted from a basic rule known as the “7:10 Rule of Thumb.”
>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. For example, let’s say that 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.
https://cdp.dhs.gov/shared/se/courses/default/AWR-923-W%2005122021%201.2-20210512144644/groups/394.html
Latest Answers