TRU-ART: A cost-effective prototypical neutron imaging technique for transuranic waste certification systems

The certification of defense radioactive waste as either transuranic or low-level waste requires very sensitive and accurate assay instrumentation to determine the specific radioactivity within an individual waste package. The assay instruments that are currently fielded at various Department of Energy sites can certify a large portion of the defense waste; however, they are incapable of determining the location of the radioactive material within a waste package. An assay instrument that employs a new technique (TRU-ART), which can identify the location of the radioactive material within a waste package, was designed, fabricated, and tested to potentially enhance the certification of problem defense waste drums. In addition, the assay instrumentation has potential application in radioactive waste reprocessing and neutron tomography.The assay instrumentation uses optimized electronic signal responses from an array of boral- and cadmium- shielded polyethylene-moderated $\sp3$He detector packages. Normally, thermal neutrons that are detected by $\sp3$He detectors have very poor spatial dependency that may be used to determine the location of the radioactive material. However, these shielded-detector packages of the TRU-ART system maintain the spatial dependency of the radioactive material in that the point of fast neutron thermalization is immediately adjacent to the $\sp3$He detector. The TRU-ART was used to determine the location of radioactive material within three "mock-up" drums (empty, peat moss, and concrete) and four actual waste drums.The TRU-ART technique is very analogous to emission tomography. The "mock-up" drum and actual waste drum data, which were collected by the TRU-ART, were directly input into a algebraic reconstruction code to produce three-dimensional isoplots.Finally, a comprehensive fabrication cost estimate of the fielded drum assay system and the TRU-ART system was determined, and, subsequently, these estimates were used in a cost-benefit analysis to compare the economic advantage of the respective systems.U of I OnlyETDs are only available to UIUC Users without author permissio