Analysis of Delayed Neutrons and Development of a Laser-Based Technique for Nuclear Forensics

Bearing in mind the aims and goals of nuclear forensics and national non-proliferation mission, a delayed neutron detection method was developed for the purpose of detecting and quantifying fissile material commonly used in the production of nuclear weapons. This method involves the irradiation of solutions of various concentrations of special nuclear material uranium and plutonium in the University of California, Irvine’s TRIGA ® nuclear reactor. Delayed neutrons emitted from the samples post-irradiation are then detected and counted using the delayed neutron system. Decay spectra of the emission and detection of delayed neutrons from these samples were constructed and analyzed in an effort to observe similarities and differences in decay behavior of uranium and plutonium. The correlation of decay spectra from ranging concentrations was also noted. Based on the patterns and trends found, characterization and quantification of the special nuclear material were possible. This method can potentially one day be implemented for the improvement of current safeguards of nuclear material. At Sandia National Laboratories, scientists are also making advancements in nuclear forensics. Researchers are currently working on developing a portable and time-efficient laser-based method of detection of noble gases released from a clandestine nuclear test. This method will help to verify compliance with the Comprehensive Test Ban Treaty which bans all nuclear testing. This trace noble gas detection platform is an ongoing project at Sandia and will hopefully be implemented in the near future.