Radiation Exposure Questions

[BrownBagger]

I was killing time recently, watching an old NOVA documentary on the Fukishima reactor disaster. They got into exposure levels, reporting that the max dose for nuclear plant workers is 250 miliseverts, while the lethal dose is generally considered about 600 miliseverts. The typical CT scan, I've read, is somewhere in the 14 milisevert range.

Perhaps that's why my late dad, who worked in nuclear power plants, always scoffed at my fears of excessive radiation exposure from scans. (He died of metastisized prostate cancer at age 80, which I presume was not directly related to any radiation exposure). Anyway, he's not around to pose this question to, so I thought someone on this board might have some insight.

My question is this: is the duration of the exposure factored into the exposure levels reported? In other words, if I receive 14 miliseverts for 60 seconds and a nuclear plant worker receives that same 14 milisevert dose for an hour, what's the difference, other than he's getting 60 times the exposure that I did. Put another way, is the exposure cumulative, so that a 1-milisevert exposure for one hour equals 60 miliseverts? Is that how it works? Put yet another way, if a plant worker is exposed to 100 miliseverts, which many Fukushima workers were, would their exposure time be limited to must 2.5 minutes? Are the limits (say, 250 miliseverts) annual accumulated exposures, or just the limit to multiple exposures over the course of a year?

I get between 6 and 10 CT scans annually. Assuming that accumulation matters, I get exposed to between 84 and 140 miliseverts annually. Still well below the max for a nuclear plant worker, but probably higher than most will actually see. As for the average person, I glow by comparison.

Hope these questions make sense.

[mypinkheaven]

I'm no radiation physicist, but I think the exposure is measured in amount/duration. It is cumulative.

http://radiationsurvival.blogspot.com/