Uranium assay and trace element analysis of the fourth collaborative material exercise samples by the modified Davies-Gray method and the ICP-MS/OES techniques

Journal of Radioanalytical and Nuclear Chemistry - An international group of laboratories participating in CMX-4 subjected three samples to comparative nuclear forensic analysis using uranium assay...     

Age determination of plutonium material in nuclear forensics by thermal ionisation mass spectrometry

Age is a key parameter when deducing the history of plutonium material, i.e. the plutonium produced in the nuclear reactors. This is of vital importance, when a smuggled plutonium sample has been seized and the origin has to be determined. A methodology is described which allows accurately to determine the age of plutonium material by thermal ionisation mass spectrometry using independent parent/daughter relations. This has been demonstrated for Reference Materials of known ages as well as for real samples. The already established method using gamma spectrometry is compared to this.     

The application of radiochronometry during the 4th collaborative materials exercise of the nuclear forensics international technical working group (ITWG)

Journal of Radioanalytical and Nuclear Chemistry - In a recent international exercise, 10 international nuclear forensics laboratories successfully performed radiochronometry on three low enriched...     

Interactive evolutionary multi-objective optimization for quasi-concave preference functions

We present a new hybrid approach to interactive evolutionary multi-objective optimization that uses a partial preference order to act as the fitness function in a customized genetic algorithm. We periodically send solutions to the decision maker (DM) for her evaluation and use the resulting preference information to form preference cones consisting of inferior solutions. The cones allow us to implicitly rank solutions that the DM has not considered. This technique avoids assuming an exact form for the preference function, but does assume that the preference function is quasi-concave. This paper describes the genetic algorithm and demonstrates its performance on the multi-objective knapsack problem.     

Determination of rare-earth elements in uranium-bearing materials by inductively coupled plasma mass spectrometry

A novel and simple analytical procedure has been developed for the trace-level determination of lanthanides (rare-earth elements) in uranium-bearing materials by inductively coupled plasma sector-field mass spectrometry (ICP-SFMS). The method involves a selective extraction chromatographic separation of lanthanides using TRU™ resin followed by ICP-SFMS analysis. The limits of detection of the method proposed is in the low pg g⁻¹ range, which are approximately two orders of magnitude better than that of without chemical separation. The method was validated by the measurement of reference material and applied for the analysis of uranium ore concentrates (yellow cakes) for nuclear forensic purposes, as a potential application of the methodology.     

Age determination of plutonium material in nuclear forensics by thermal ionisation mass spectrometry

Age is a key parameter when deducing the history of plutonium material, i.e. the plutonium produced in the nuclear reactors. This is of vital importance, when a smuggled plutonium sample has been seized and the origin has to be determined. A methodology is described which allows accurately to determine the age of plutonium material by thermal ionisation mass spectrometry using independent parent/daughter relations. This has been demonstrated for Reference Materials of known ages as well as for real samples. The already established method using gamma spectrometry is compared to this.     

Origin Determination of Plutonium Material in Nuclear Forensics

The properties of a composite ion exchanger containing potassium nickel ferrocyanide incorporated in silica gel matrix are described. The sorbent was prepared in the form of spherical beads. For the characterisation of the ion exchanger X-ray diffraction, electron microscopy, IR and Mössbauer spectrometry were used. The sorbent was used for the sorption of radiocesium from model solutions as well as from radioactive waste solutions (NPP Jaslovské Bohunice, Slovakia).     

A careful look at the importance of criteria and weights

We investigate the connection between weights, scales, and the importance of criteria, when a linear value function is assumed to be a suitable representation of a decision maker’s preferences. Our considerations are based on a simple two-criteria experiment, where the participants were asked to indicate which of the criteria was more important, and to pairwise compare a number of alternatives. We use the participants’ pairwise choices to estimate the weights for the criteria in such a way that the linear value function explains the choices to the extent possible. More specifically, we study two research questions: (1) is it possible to find a general scaling principle that makes the rank order of the importance of criteria consistent with the rank order of the magnitudes of the weights, and (2) how good is a simple, direct method of asking the decision maker to “provide” weights for the criteria compared to our estimation procedure. Our results imply that there is reason to question two common beliefs, namely that the values of the weights would reflect the importance of criteria, and that people could reliably “provide” such weights without estimation.     

A computer graphics-based Decision Support System for multiple objective linear programming

In this paper we propose a computer-graphics based Decision Support System for multiple objective linear programming that builds on the VIG system (Visual Interactive Goal programming). The essential part of the VIG system is Pareto Race, a dynamic and visual approach for exploring the efficient frontier of a multiple objective linear programming problem. Our objective is to extend Pareto Race to large-scale multiple objective linear programming. The approach works with any efficient solutions that are in general not extreme point solutions. Interactive use of computer graphics plays a central role. The approach, the underlying theory, and an illustrative example are described.