Determination of <Superscript>93</Superscript>Zr and <Superscript>237</Superscript>Np in nuclear power plant wastes

A combined radioanalytical method for determination of ⁹³Zr and ²³⁷Np (as well as other actinoids) in radioactive wastes has been developed. Analytes were co-precipitated on iron(II)-hydroxide, separated and purified on UTEVA columns, and detected by inductively coupled plasma mass spectrometry. According to Zr and Np, 65 and 75% yields were achieved, respectively.     

The consistency principle for games in strategic form

We start with giving an axiomatic characterization of the Nash equilibrium (NE) correspondence in terms of consistency, converse consistency, and one-person rationality. Then axiomatizations are given of the strong NE correspondence, the coalition-proof NE correspondence and the semi-strong NE. In all these characterizations consistency and suitable variants of converse consistency play a role. Finally, the dominant NE correspondence is characterized. We also indicate how to generalize our results to Bayesian and extensive games.     

Theτ-value for games on matroids

In the classical model of games with transferable utility one assumes that each subgroup of players can form and cooperate to obtain its value. However, we can think that in some situations this assumption is not realistic, that is, not all coalitions are feasible. This suggests that it is necessary to raise the whole question of generalizing the concept of transferable utility game, and therefore to introduce new solution concepts. In this paper we define games on matroids and extend theτ-value as a compromise value for these games. This work has been partially supported by the Spanish Ministery of Science and Technology under grant SEC2000-1243.     

Rapid methods for the determination of long-lived radionuclides in environmental samples by ICP-SFMS and radioanalytical techniques

Two improved sample preparation methods for the determination of americium and plutonium (Method 1) and plutonium (Method 2) from environmental samples by inductively coupled plasma sector field mass spectrometry (ICP-SFMS) and alpha spectrometry are presented. Both procedures involve a rapid CaF₂ co-precipitation step for pre-concentration and matrix removal followed by extraction chromatographic separations. The average recovery after sample preparation was better than 85 % for both americium and plutonium. The method developed also focused on the elimination of possible interferences in the mass spectrometric analysis caused by molecular ions (e.g. ²⁰⁸Pb¹⁶O ₂ ⁺ or ²³⁸U¹H⁺) by employing suitable matrix separation prior to ICP-SFMS analysis of the desolvated sample. Isotopes with alpha energies similar to the analytes that may cause interferences in alpha spectrometric analysis were also separated. For ²³⁹Pu, ²⁴⁰Pu, ²⁴¹Pu and ²⁴¹Am detection limits of 15, 9.2, 14 and 23 fg g⁻¹, respectively were achieved by ICP-SFMS, and 0.1 mBq obtained by alpha spectrometry. The methods developed are especially applicable for monitoring purposes of anthropogenic transuranium elements, as the analysis (sample preparation and ICP-SFMS measurement) can be carried out within 6 hours for one batch of samples.     

The τ-value,The core and semiconvex games

Theτ-value for cooperativen-person games is central in this paper. Conditions are given which guarantee that theτ-value lies in the core of the game. A full-dimensional cone of semiconvex games is introduced. This cone contains the cones of convex and exact games and there is a simple formula for theτ-value for such games. The subclass of semiconvex games with constant gap function is characterized in several ways. It turns out to be an (n+1)-dimensional cone and for all games in this cone the Shapley value, the nucleolus and theτ-value coincide.     

Levels and transitions in126Te

The decay of¹²⁶Sb to¹²⁶Te is studied by use of Ge(Li) detectors in singles and coincidence arrangements. The gamma-gamma directional correlations of six cascades are measured. A level scheme is constructed where all transitions observed are located. The characteristics of several of the levels are assigned, on basis of the logft values deduced and the directional correlation results. Mixing ratios are deduced for three transitions. From the comparison of the relative intensities ofE1 andE2 transitions depopulating the same levels, threeE1 transitions are concluded to be strongly retarded.     

Strongly essential coalitions and the nucleolus of peer group games

Most of the known efficient algorithms designed to compute the nucleolus for special classes of balanced games are based on two facts: (i) in any balanced game, the coalitions which actually determine the nucleolus are essential; and (ii) all essential coalitions in any of the games in the class belong to a prespecified collection of size polynomial in the number of players. We consider a subclass of essential coalitions, called strongly essential coalitions, and show that in any game, the collection of strongly essential coalitions contains all the coalitions which actually determine the core, and in case the core is not empty, the nucleolus and the kernelcore. As an application, we consider peer group games, and show that they admit at most 2n−1 strongly essential coalitions, whereas the number of essential coalitions could be as much as 2ⁿ⁻¹. We propose an algorithm that computes the nucleolus of an n-player peer group game in time directly from the data of the underlying peer group situation.Research supported in part by OTKA grant T030945. The authors thank a referee and the editor for their suggestions on how to improve the presentation     

The interval Shapley value: an axiomatization

The Shapley value, one of the most widespread concepts in operations Research applications of cooperative game theory, was defined and axiomatically characterized in different game-theoretic models. Recently much research work has been done in order to extend OR models and methods, in particular cooperative game theory, for situations with interval data. This paper focuses on the Shapley value for cooperative games where the set of players is finite and the coalition values are compact intervals of real numbers. The interval Shapley value is characterized with the aid of the properties of additivity, efficiency, symmetry and dummy player, which are straightforward generalizations of the corresponding properties in the classical cooperative game theory.