Microbeam analysis of irradiated nuclear fuel

Abstract

Abstract. Microbeam analysis is widely used in the nuclear power industry. It is used to characterise the as-fabricated fuel, for routine post-irradiated examination and for research into the mechanisms of phenomena that limit the energy production of the fuel. The techniques most commonly used are wavelength-dispersive electron probe microanalysis, scanning electron microscopy and secondary ion mass spectrometry. Other microbeam analysis techniques that have been successfully applied to irradiated nuclear fuel are transmission and replica electron microscopy, X-ray fluorescence and micro X.-ray diffraction. Specific examples illustrating the past and present use of microbeam analysis in nuclear research establishments are presented with emphasis on the unique results they provide. As an aid to understanding, some basic facts about nuclear fuel rods and their irradiation are first given. This is followed by a description of features that set apart the microbeam analysis of high radioactive materials from standard practice.

Unresolved challenges in the microanalysis of actinides and nuclear materials

“…European Commission -Joint Research Centre, United States Quantitative x-ray microanalysis is a valuable tool for a wide range of nuclear applications. Typical examples for applications in the field of actinide materials are the analysis of fresh or spent nuclear fuel (post irradiation examination -PIE), the quantification of Pu or Am in materials used in radioisotope thermoelectric generators (RTGs) for space applications (see latest Mars rover Perseverance), or the analysis of materials formed during severe nuclear accidents like Three Mile Island, Chernobyl, and Fukushima [1][2][3].…”

Improved Protocol for the Quantification of Actinides (Th, U, Np, Pu, Am, and Cm) Using Electron Probe Microanalysis

“…Perhaps the most important nondestructive micro-analytical method that is used to improve the safety and performance of nuclear fuels with the potential of reducing high-level waste is electron probe microanalysis (EPMA) (Walker, 1999; Brémier et al, 2003, 2016; Lamontagne et al, 2007; Walker et al, 2012; Bottomley et al, 2014; Capriotti et al, 2014; Moy et al, 2014; Wiss et al, 2017; Gerczak et al, 2018; Llovet et al, 2020). EPMA is a fast and reliable tool usually applied to earth and material sciences, yet encounters several technical obstacles in nuclear fuel analysis.…”

“…These facilities are globally rare, while research and development on nuclear fuels is strictly regulated by (inter)national policies. Second, microprobe counting detectors and other sensitive parts in the column are exposed to high β- and γ-irradiation from the samples, which demands special and costly shielding (Walker, 1999; Lamontagne et al, 2007; Walker et al, 2012). Third, well-polished surfaces are crucial for the quality of quantitative analysis using EPMA, yet all of the common sample preparation steps such as embedding, grinding, polishing, and controlling the polishing status under a microscope have to be carried out in glove boxes (Walker, 1999; Lamontagne et al, 2007; Wright et al, 2018), but these “simple” steps are not necessarily available all in one glove box.…”

Simultaneous isotopic analysis of fission product Sr, Mo, and Ru in spent nuclear fuel particles by resonance ionization mass spectrometry

“…This results in greater production of fission products, and also in greater transmutation of those species due to neutron capture. In addition, elemental and isotopic compositions can change significantly within a few hundred micrometers of the edge of an individual fuel pellet due to the skin effect, in which epithermal neutrons are strongly captured by 238 U, resulting in copious production of Pu [5][6][7][8] . This in turn results in changes in the fission product distribution at the pellet edge because fission products of 239 Pu have a different elemental and isotopic distribution than those of 235 U.…”