final answer on radiation shielding vs. 1975 Summer Study

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Thanks for looking into this, Joe.

Regards,

Mike Combs

> So the Summer Study recommended 2 meters of slag. From what you say,
> sounds like insisting on 4 meters should not be considered needlessly
> paranoid. Do I have that right?

Well let's see, I'm not sure what density this slag would have, but
let's assume it's similar to concrete, which is 2400 kg/m^3.

So to get 10,000 kg, we need 4.2 m^3 of the stuff... so yeah, about 4
meters deep or so, to meet the Summer Study's own target of 0.5 rem/yr.

As for whether that's paranoid, there seems to be quite a lot of lively
discussion in the community today about how much radiation is tolerable.
The short answer seems to be, we just don't know -- we have little
data on the effects of this kind of radiation on humans.

But it seems to me that when talking about colonies, what matters more
than actual risk is *perceived* risk. The general public is very
skittish about anything with the word "radiation" in it. So, even if
there were good solid data showing that 10X Earth-normal radiation
levels won't have any measurable effect on life expectancy, I think
there would be strong opposition. (Of course I guess this could just be
a self-selection process for your colonists.)

On the other hand, if your dosimeter reads the same (or less) on the
colony as it does on Earth, then even the most radiation-paranoid should
have a hard time making a case.

Background radiation levels on Earth are about 0.3 rem/yr, but with
dental X-rays, granite counters, etc., most Americans absorb 0.6 rem/yr.
So I'd say that 0.5 rem/yr is a pretty reasonable target.

Cheers,
- Joe

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