Chromatographic separations for fission products and actinides determination by different analytical techniques: mass spectrometry and radiometry
Authors:   , Perna Lorenzo 
Published: September 2023

Due to the nuclear testing, reentry and disintegration of nuclear powered satellites, nuclear reactor accidents, uranium nuclear fuel cycle and nuclear weapons production, actinides have been introduced into the environment. Proposed disposal of high-level radioactive waste in mined repositories in geologic formation as well as the storage and disposal of uranium and plutonium from weapons dismantlement are further possible sources for actinide releases to the environment. The mobilization of radionuclides in the environment has been studied for many years with the prime objective of tracing the routes by which they accumulate in the food chain and become available for human consumption. Therefore, it is necessary to have available accurate, reliable and precise analytical methods to determine actinides and fission products in environmental samples as well as their isotopic ratio. These procedures should also be as fast as possible in order to give results in radiological emergency cases to take decision for radiation protection of the environment and human beings.<br/><br/>In this Ph.D. thesis, different kinds of phases for liquid chromatography have been tested to achieve the separation of the interfering elements and isotopes before the mass spectrometry and -spectrometry measurements. UTEVA and TEVA extraction resin (Eichrom Industries, USA) have been packed in chromatographic column as stationary phases and used for the separation of tri, tetra and hexavalent actinides and for the separation of trivalent lanthanides (La-Eu) and actinides, respectively. IonPac CS5A and CS10 (Dionex, Sunnyvale, USA) ion chromatography column were used for the simultaneous separation of actinide and lanthanides elements and for the actinides separation. The columns were coupled on-line to an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) to solve isobaric interferences between actinide and lanthanide elements and off-line to a -spectrometer to solve the energy interferences between the analytes. Moreover, an investigation on the use of the UTEVA resin and IonPac Trace Cation Concentrator II column (TCC-II from Dionex, Sunnyvale, USA) as preconcentrator columns for actinide and lanthanide elements has been carried-out.<br/><br/>The analytical measurements have been made by mass spectrometric as well as by radiometric techniques. ICP-MS has been used for the characterization of spent nuclear fuels in terms of actinides and lanthanides content and burn-up calculation as well as for the determination of the long-lived actinides and lanthanides in environmental samples. - and -spectrometry have been used for 241Am determination in sediments and soils samples. -spectrometry and Liquid Scintillation Counting (LSC) have been used to analyze the eluted fractions from on-batch experiments. <br/><br/>The results obtained with the analytical procedures developed, for spent nuclear fuel solutions as well as for environmental samples, were always compared to those obtained by other independent techniques and good agreements have been always achieved.