Nuclear Forensic Lab Interoperability and Criminal Investigation
Health Canada Ottawa, Ontario Canada
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The elemental and isotopic composition of radiological or nuclear material, along with its macroscopic and microscopic appearance, is often unique to its mode of production. In this way, such data may be used as a nuclear fingerprint for source attribution should such material be interdicted. A key component of the nuclear fingerprint for source attribution is the determination of the elapsed time age since the last chemical purification. During production, the nuclear material is purified from radioactive decay products progeny. After separation, the decay products begin to accumulate. Measuring the parent-progeny ratio therefore provides the age of the nuclear material. An isotope ratio that may be used for dating nuclear material is referred to as a radiochronometer. Currently, there is a global need for certified reference materials for nuclear forensics work, including those for radiochronometry. This project aimed to validate reference materials and procedures for Nuclear Forensics Laboratories that will ensure laboratory interoperability for the measurement of radiochronometers. Most of the focus of this project was on the development of the cobalt-60nickel-60 radiochronometer, for which a reference material and standard operating procedure were developed and validated through a series of inter-comparison exercises, the latter of which involved five Canadian and one American laboratory. Two other radiochronometers, cesium-137barium-137 and strontium-90zirconium-90, were of interest to this project. To this end, the participating U.S. laboratory was able to provide their work instruction describing age dating of various sources, including thecesium-137barium-137 and strontium-90zirconium-90 radiochronometers.