Plutonium Isotopic Composition by Gamma-ray Spectrometry

摘要

One of the most important aspects of the fissile material processing and storage is its accounting at every stage. This may require assay of fissile material in various forms, e.g. finished form as fuel rods or pins, waste in the form of solution or solid and any other intermediate form. The most commonly used method for fissile material accounting is by electrochemical method. However, this method is destructive and time consuming. Neutron coincidence counting has proved to be a very useful technique for assay of plutonium bearing samples. However, determination of the total plutonium amount by this method requires prior knowledge of the isotopic composition of the plutonium sample. A plutonium sample obtained from irradiated natural uranium as fuel consists of five plutonium isotopes namely ~(238, 239, 240, 241, 242)Pu. Depending upon the burn up of the fuel, plutonium samples are categorised as "low-burn up (research reactor grade)" or "high-burn up (power reactor grade)" sample.