Nuclear Properties and Isotopes

There are 25 known isotopes of uranium, ranging in mass from 217 to 241, but only three occur naturally at significant concentrations—and — with natu- 

When discussing the isotope composition of uranium, the abundance is usually given in units of atom percent (i.e., the relative number of atoms of each isotope in a given mass of uranium) rather than in terms of weight percent (i.e., the relative weight of each isotope in the uranium mass). Thus, the weight percent of each isotope in natural uranium differs slightly from the atom percent as shown in parenthesis in Table 1.2. is the only fissile isotope of natural uranium, but the artificial isotope (produced in thorium-fueled nuclear reactors) is also fissile. All uranium isotopes are radioactive and the half-lives of the isotopes of importance are shown in Table 1.2. Due to the important role of radioactivity in the uranium industry, a short discussion is presented in Frame 1.1. 

Isotope atom% (wt%) (Years) Pathway Energy Product Bams ( T  

Source Based on data from https //en.wikipedia.org/wikiAJranium, accessed July 26, 2014. 

Note SF, spontaneous fission o the cross section for fission—the cross section of natural luanium is 3.4 barn for capture of thermal neutrons and 4.2 for fission. 

---