NPs can use the abductive, deductive, and inductive forms of reasoning to adopt a rational and consistent approach to transforming effective data into accurate diagnoses. A case example is used throughout the article to illustrate how these classic logical reasoning skills may be combined with knowledge and experience to address issues of diagnostic accuracy and decrease diagnostic errors.

Electrochemical reprocessing (also commonly known as pyroprocessing) of used nuclear fuel is an alternative to aqueous reprocessing that confers a number of advantages, including the ability to process more recently discharged fuel, smaller resultant waste volumes, and the lack of isolation of plutonium in the product stream. While electrochemical reprocessing systems have seen a significant research and development effort, nuclear safeguards and the security of these systems remain underdeveloped, particularly given the significant differences in operating environment and process flow sheet compared with established aqueous methods. In this paper we present an overview of the current state of the art for several of the most promising candidate techniques for material accountancy and process monitoring measurements for electrochemical separations facilities for used nuclear fuel, specifically passive radiation signatures (gamma spectroscopy, neutron spectroscopy, alpha spectrometry, calorimetry, and microcalorimetry), active radiation signatures (X-ray interrogation and its derivatives, high-resolution X-ray, k-edge densitometry, and hybrid k-edge densitometry; laser-induced breakdown spectroscopy; active neutron interrogation and neutron coincidence counting; inductively coupled plasma mass spectrometry; and optical measurements such as ultraviolet visible spectroscopy, near-infrared spectroscopy, and Raman spectroscopy), and control and process state variable monitoring (cyclic voltammetry and bulk measurements such as level and density, load cell forces, and off-gas monitors). This assessment includes an evaluation of each measurement's respective modality (i.e., whether the measurement relates to elemental, isotopic, or other properties), published best estimates of measurement precision, measurement latency, and an overall evaluation of each technique's level of technical maturity. Additionally, this study assesses the most likely locations within the pyroprocessing flow sheet where measurements may be deployed, the physical information required to properly capture the behavior of such measurements, and potential modeling strategies for such measurements. This latter component thus serves to inform future development of process monitoring models in existing and proposed electrochemical separations simulation models.

In this paper, we investigate the possibility of plutonium quantification within the electrorefiner vessel of an electrochemical separation facility via the use of the (α,n) neutron signature from dissolved actinides. As a potential alternative means to traditional spontaneous fission tracking, such an analysis may provide a more reliable tracking capability of plutonium within systems that produce a mixed matrix sample that yields a large (α,n) source term relative to that of spontaneous fission. This assessment includes an evaluation and breakdown of nuclides within the refining unit to differentiate the source of neutrons and then the ratio between (α,n) emissions to total neutron emissions given a range of fuel parameters. Next, we provide an assessment of the origin of (α,n) neutrons in relation to multiple isotopes of plutonium to determine the potential of a direct tracking method. Preliminary results indicate that the (α,n) contribution for electrochemical systems is much higher than in its aqueous counterpart and rivals spontaneous fission yield in terms of magnitude. Furthermore, 238 Pu is shown to be a main contributor to the (α,n) yield for the fuel examined in this study.

No abstract