[ RadSafe ] Detecting DU at a distance via beta particle emission.

[Dan W McCarn]

Hi:

I always thought that the "gold standard" for DU was measuring the Pa-234
gamma photopeak at 1,001 KeV.

Petrophysical probes have been developed with HPGe detectors to measure the
concentration of U in rock based on the detection of the coincident 1,001
KeV gamma photopeak from the Pa-234m beta decay to U-234. Since the U-238 is
in secular equilibrium with Pa-234 in about 200 days, the chemical U made be
determined with better precision than gross gamma logging methods.

Since the "bottom half" of the decay chain requires 1-2 million years to
reach secular equilibrium (Radium progeny) gross gamma techniques using
NaI(Tl) detectors may over- or under-estimate ore grades in U deposits
depending on geochemical remobilization of uranium in the ore deposit.

Dan ii

Dan W. McCarn, Geologist; 3118 Pebble Lake Drive; Sugar Land, TX 77479; USA
Cell: +1-505-710-3600; Home: +1-281-903-7667; Fax: +1-713-241-1012; Office:
+1-713-241-5726; Austria:  +43-676-725-6622
mccarn at unileoben.ac.at           HotGreenChile at gmail.com
Dan.McCarn at shell.com