You should have answered that many times... but what are the estimated levels for radiation absorption outside Van Allen belts?

I got some values from here, but they just talk about galactic cosmic rays. Are they close?

Thanks.

As you've probably gathered from even a little reading, there isn't such a thing as "amount of radiation."

Much depends on the energy levels, kind of sheilding, kind of particle, time of exposure. For instance, you could stand near a pile of depleted uranium in total comfort. If you were daring, you could even EAT a handful. Most of the energy is released via Alpha particles that have too little oomph to penentrate your skin. But if you got any DU in your bloodstream, the stuff has a nasty habit of collecting in a few places so it can irradiate some of your internal organs at close range.

Cosmic rays get mentioned a lot because their energies are very high; they can slam through light shielding and in metals give rise to secondary radiation (as I understand it...feel free to correct me, fellows!) The sun is better behaved, except during flares where the kinds of particles released changes and the amount increases radically.

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DU perhaps isn't the best example. It is very long lived. It is chemically useless to the body and so doesn't get absorbed. The result is that you'd have to eat a fair bit of DU before you suffered any ill effects. Radio-iodine, now that's a different story.

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Hi,

I was talking about the estimated absorbed dose. Things like how much REM/year for an light shielded craft. Sorry if I wasnt clear enough.

I the meanime, I found some texts on internet that say something about those levels. They match with the 0.3 - 1 Sievert/year that the first text talks about. It seems that galactic cosmic rays are the only thing that matters if there is no SPE taking place.

That seems about right to me; most of the materials I use are graphs for certain kinds of exposures behind certain types and thicknesses of materials. That's really the kind of information we're interested in as engineers, but it doesn't mean much to someone who isn't contemplating building something. The numbers vary greatly depending on what conditions the compiler of the data has assumed. However, designing for longevity on the scale of years requires us to consider solar events, and so the average exposures according to many sources includes predicted numbers and strengths of these events.

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I always understood that uranium, like other heavy metals was toxic and caused damage to the nervous system entirely apart from any possible radiation. But I could definitely be wrong.

Strontium-90 is a nasty one. Its a beta emitter that is chemically similiar to calcium, so it gets taken into your bones, and irradiates your bone marrow. Its a common component of radioactive fallout.

But anyhow - I was under the impression that the Apollo craft passed through the belts very quickly, minimising the dose received by the astronauts.

It is toxic, in large amounts it will cause kidney failure rather than nervous system damage though.

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The different metals, chemically speaking, have different properties. Some, like plutonium and those other mentioned, behave like mercury and other heavy metals and stay in the body for long periods of time. Uranium, however, is eliminated and does not accumulate forever. It's still dangerous while it's in there, but the chemical effects are less pronounced. Yes, it would cause kidney failure (chemically) if ingested in sufficient quantities.

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