Re: Fiesta & Radon

[FRAMEP@ORAU.GOV]

          Fiesta ware plates don't emit radon at a greater rate than
          ordinary dinner plates. The color in the glaze of Fiesta red
          (as it is known in the trade) comes from uranium: natural
          uranium if pre-WWII, and depleted uranium if from the 1950s.
          The measurements I've seen suggest concentrations of 3000 to
          4000 pC of uranium 238 per square cm. Prior to WWII the
          glaze (not the plate itself) contained up  to 15 to 20 % by
          weight uranium. The problem is that there is no significant
          amount of radium 226: the uranium has been chemically
          processed so the chain is not in equilibrium!

          I have a copy of a masters thesis claiming that the plates
          cotain radium and that the radon escapes but the author
          appears to have confused the 184 keV gamma of U-235 with the
          186 keV gamma of Ra-226. The proof is the near complete
          absence of Bi-214 and Pb-214.

          However, after a million or so years, the Ra-226 will be in
          equilibrium and a  plate might have 3000 pCi of
          Ra-226 per sq cm. If the plate has an area of 500 cm square
          this 1.5 million pCi of Ra-226 and hence Rn-222. Dividing
          this by the volume of a 15' x 15' room (50,000 liters
          assuming  8' ceiling) we get 30 pCi per liter. This
          ridiculous calculation assume complete loss of the radon
          from the glaze. If this sort of thing happened in reality,
          we'd all be dead of lung cancer,except for those that
          believe in hormesis who would live forever :).

          Regards, Paul W. Frame
          Oak Ridge Associated Universities
          framep@orau.gov