Special Isotopes

Uranium consists of a mixture of isotopes. All uranium sources, in general, are certified on the basis of specific activity and mass. EZIP calculates the activity percentages of the isotopes present using technical data provided by the vendor of the material, and writes a Technical Data Sheet. The Technical Data Sheet is a part of the Certificate of Calibration. It is very difficult to separate U-234 from U-235. Since the specific activity of U-234 is 2867 times that of U-235, a 1% amount by mass of U-234 in U235 will create an activity of U-234 28 times higher than that of U-235. Since the amount of uranium mass itself in a solution could be substantial, the solution densities could be much higher than the diluent (as high as 1.5 g/cc). Uranium sources are generally electroplated on an aluminum surface.

Natural uranium has the following atom % composition: U-234 = 0.0055 atom % U-235 = 0.720 atom % U-238 = 99.2745 atom % Enriched means higher atom % of U-235 than natural uranium. Depleted means lower atom % of U-235 than natural uraniu

Plutonium

Plutonium consists of a mixture of isotopes. EZIP calculates the activity percentages of the isotopes present using technical data provided by the vendor of the material, and writes a Technical Data Sheet. The Technical Data Sheet is a part of the Certificate of Calibration. Plutonium isotopes are complicated by the presence of Pu-241, which is beta active, and has a relatively short half-life of 14.4 years. Its daughter is Am-241, which is alpha active with significant gamma rays.

This long-lived P-32 standard is the beta emitting P-32 daughter of the long-lived Si-32 parent. The standard mounting for this source is the A capsule with a 0.002” (0.051 mm) AI window. This window will absorb more than 60% of the Si-32 225 keV betas and less than 5% of the P-32 betas. Standards are prepared with the P-32 in equilibrium with the parent Si-32.