[ RadSafe ] Rn-222 from Depleted Uranium

[Dan McCarn]

How much Rn-222 activity in 300 kg of depleted U? Virtually none because the time to reach secular equilibrium is 1-2 million years. Soils already have ingrowth products from the uranium minerals in the parent rock. 

Dan W McCarn
108 Sherwood Blvd
Los Alamos, NM 87544 USA
+1-505-670-8123
Sent from my iPhone

On Aug 20, 2013, at 12:18 PM, Andrew McGechaen <A.McGechaen at BuffaloInspection.com> wrote:

> Dear Sir/Madam,
> 
> My building stores about 300kg of depleted uranium. I have read that the indoor radon hazard in buildings originates from decay products of uranium in soil. Checking the Radium Series, I noted U-234 (245500a) -> Th-230 (75380a) -> Ra-226 (1602a) -> Rn-222 (3.8235d), with the attached half-lives. Fetter and von Hippel (1997) give U-234 at a concentration of 7 ppm in DU.
> 
> Is it safe to ignore the decay chain of U-238 to U-234, and consider only the initial concentration of U-234 ?
> 
> Is it realistic to assume that the residue of Ra-226 in the DU would be zero after chemical refinement?
> 
> I assume the U was depleted and chemically refined years or decades ago. What activity of Rn-222 would exist now?
> 
> Might radon escape through cracks or communicating voids in the metallic uranium?
> 
> Might any appreciable quantity of radon escape from the uranium metal by Fickian diffusion?
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