How often does Uranium ore emit radiation particles?
- pisgahchemistLv 72 years agoFavorite Answer
Uranium ore consists of a lot of different materials, with only a small amount being uranium, along with the decay products of uranium. The uranium in the ore consists mainly of U-238. (The relative abundance is 99.2745%). Uranium-238 is long-lived (the half-life is 4.47x10^9 y, roughly the age of the Earth). The rate at which U-238 atoms decay depends on the total number of atoms originally present and where we are in time since then. Even at that, the emission of decay products from the ore is essentially continuous. That's because there are so many atoms present even though they constitute a small percentage of the mass of the ore. Yet each atom will decay when it is good and ready. No external stimulus can cause a particular atom to decay. As the number of U-238 atoms decrease, the rate of decay decreases. What makes actually measuring the number of decay events problematic is that not all the clicks on the Geiger counter are from U-238. There are numerous decay products (daughter isotopes) which are also radioactive and decay at different rates. The Geiger counter can't distinguish between the alpha and beta particles, or gamma rays*, nor can it tell what radionuclide decayed.
*There is a way to measure the amounts of alpha radiation, beta radiation and gamma radiation. Alpha radiation can only go through the mica window at the end of the Geiger-Mueller tube as can beta radiation. Gamma rays can penetrate the tube anywhere. Placing the plastic cap over the window will block the alpha radiation, and placing a piece of aluminum in front of the window will block the beta radiation. Measure the total count rate and subtract the background count rate. Add the plastic cap. The count rate will drop. Those are the alpha particles. Add the aluminum plate. The count rate will drop again. Those are the beta particles. The remaining counts are from gammas. There's a bit more to it than that, like making multiple measurements at each point and getting the mean and standard deviation for each, and propagating the uncertainties as you do the subtractions.
- DrBob1Lv 72 years ago
It depends on the particular isotope. An atom of 238U will probably decay within the next 4,500,000,000 years.
- MorningfoxLv 72 years ago
An ore sample with one gram of natural uranium will emit about 50,000 radiation particles per second. Typical concentrations in ore are only 0.05% to 0.20%, so you need about 1000 grams of ore to have 1 gram of uranium.