Abstract
The structure identification of the fraction of minor products obtained during radiolysis of tributylphosphate (TBP), the solvent used in reprocessing of nuclear fuel, is reported. These results were realised from the distillation residue of the EDIT loop. The primary radiolysis formed TBP radical dimerises and is transformed under oxidative nitric acid conditions into several butyl chains substituted hydroxy or nitro phosphates as well as alkylated TBP. The butyl chain hydroxylated phosphate is leading to ketones, ethers and O-ester derivatives. The structures were determined by tandem mass spectrometry (MS–MS) and isotopic labelling techniques as well as by ion filiation and isotopic exchange studies. The analytical method developed consisted of the use of the integrated GC–MS, or GC–MS–MS, isotopic labelling technique. The combination of these techniques enabled to identify and to semi-quantify most of highly functionalised TBP without their prior separation from the post radiolysis mixtures.
Highlights
The degradation of the solvent system during the nuclear fuel reprocessing procedure remains, for both economical and scientific reasons, a major problem to the nuclear energy industry
The study of these mixtures was usually performed on laboratory irradiated samples as well as on radiolysed solvent system exposed to acidic conditions, because of
In this paper we report the use of integrated tandem mass spectrometry, GC–mixtures using tandem mass spectrometry (MS–MS) and stable isotopic labelling methods to study the radiolysed solvent minor degradation products
Summary
The degradation of the solvent system during the nuclear fuel reprocessing procedure remains, for both economical and scientific reasons, a major problem to the nuclear energy industry. If this oxidation takes place by the formation of dimers followed by oxidation or by coupling of radicals TBP◦ to oxidised forms of TBP◦ Some of these oxidised dimers identified in this mixture are presented in this study (e.g., hydroxy TBP–TBP) and used for calibration purpose for gas chromatography and for tandem MS experiments. The laboratory simulation of industrial conditions, using the EDIT loop procedure to study the degradation of a real solvent system, consisted of integration of many physical and chemical treatments (e.g., alkali and acid treatments, distillation) to simulate the industrial solvent retreatment These chemical and physical treatments must be taken into account because they can modify the degradation product ratios as a result of possible secondary reactions. The fractions of simulated nuclear fuel reprocessing solvent (originate from EDIT) were fractionalised using steric exclusion chromatography [5] In this way only heavy degradation products are studied in this paper. The methodology developed in this study is perfectly transferable to the hot (radiactive) sample and other fraction treatments
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