I thought it was generally agreed that national defense, and power generation does provide a benefit to the public. If not, how can we justify commercial power generation with all its environmental harm? But moreover, this question becomes moot, depending on whether or not we subscribe to the LNT.
"The problem" is that we approach two completely different problems with one solution. I think we should aproach radiation protection in a two-pronged fashion. One approach for occupational exposure and one for environmental (public). It would require us to adopt a philosophy that it seems to me most folks in the radiation protection community already agree with.
Lots of people have pointed out the problems with using a threshold value in occupational radiation protection. We know that ICRP adopted LNT in part due to simplicity - we have to give them credit. Our standards organizations long ago wrestled with the problems of trying to implement a practical occupational radiation protection scheme. If you try to inject a threshold/hormesis into it, you have a mess. LNT is a simple model that should allow a reasonable approach to occupational dose control. You're not left trying to figure out which dose to avoid and which to allow. The only modification or qualification we might want to make is that striving for dose reduction below certain values is no longer reasonable. What that value should be might be debatable. But for this argument, we keep ALARA and say that we have a handle on this part of the issue.
With public dose, we can use a different approach. Here, it is valid to strive for "very small doses" - those that lie below the threshold value we choose for detriment. In fact, it is reasonable to maintain all doses less than the threshold - not ALARA. The idea of collective dose should be thrown out altogether, because at doses below the threshold for detriment, the risk is effectively zero per person, and therefore the collective risk is zero. Most people argue that the biggest problem with LNT is the issue of many people getting minute doses - we sit down and calculate the excess cancer risk based on significant individual doses, apply it to large populations getting trivial dose, and viola- you have a zillion excess cancer deaths --- oh my god.
So, what number to use for a public dose threshold? If we stop wrangling over the rest of the issues and concentrate on that question, I'm sure we can answer it rather effectively. We already have position statements that say we should not attempt to quantify risk below 10 rem (sorry, I don't SI). Would everybody agree that it would be fairly easy to meet a lifetime dose limit of 10 rem for a member of the public? If less than 10 rem equals no quantifiable risk, imagine how much simpler everything becomes.
Pipe dream????
--
Keith Welch
Thomas Jefferson National Accelerator Facility
Newport News VA
welch@jlab.org
Ph: (757)269-7212
FAX:(757)269-5048
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