Improved plutonium concentration analysis in specimens originating from the nuclear fuel cycle using high resolution ICP-OES

Abstract

An accurate and robust ICP-OES procedure for the reliable determination of the Pu concentration in radioactive samples was developed and subsequently cross-validated using ICP-MS. Method optimisation focused on identifying Pu emission wavelengths that are spectrally not interfered by the occurrence of emission signals of concomitant elements (e.g. Am, Np, Th, and U) in the analyte solution, thereby avoiding an otherwise necessary chemical separation of Pu from the matrix elements. To this end, a total of 43 Pu emission wavelengths were tested for their selectivity and sensitivity. The signal to background ratio of the 27 most prominent Pu emission lines ranged from $2 to 20, while relative sensitivities varied only within a factor of two. Peak widths of ICP-OES Pu signals extended from $5 pm to $11 pm, with the majority remaining <6 pm. Using a desolvating nebuliser, instrumental detection limits (LOD) were lowered by an order of magnitude compared to all previous studies. Among the finally selected, seven worthwhile Pu emission wavelengths, LODs of 2.3 mg L À1 , 3.1 mg L À1 , and 3.2 mg L À1 were obtained at l ¼ 299.649 nm, l ¼ 299.409 nm, and l ¼ 297.251 nm. Applying external calibration, several radioactive samples originating from pyrochemical separation experiments were analysed for their Pu concentration. Typical relative standard deviations of replicate Pu measurements amounted to $1% to 2%. The complementary employment of the standard addition approach confirmed the accuracy of this data as well did comparative in-house sector field ICP-MS analysis. Preliminary experiments with spent fuel solutions revealed promising Pu data highlighting the potential of ICP-OES for reliable Pu analysis in the nuclear field.

High-Resolution Inductively Coupled Plasma Optical Emission Spectrometry for 234U/238Pu Age Dating of Plutonium Materials and Comparison to Sector Field Inductively Coupled Plasma Mass Spectrometry

“…However, even modern simultaneous ICP-OES instruments (optical resolution of 10 pm) allow the application of ID to quantify the 238 U/ 235 U ratio in particular cases . The superior optical resolution of HR-ICP-OES instruments, in turn, allows it to reveal the small difference in emission wavelengths evident for different U and Pu isotopes that is known as isotope shift. ,,, While some HR-ICP-OES work on U and Pu isotopic analysis has been already reported earlier, − a closer look to the specific needs required for 234 U/ 238 Pu age dating using HR-ICP-OES is warranted here.…”

“…As this so-called “isotope shift” between various isotopes frequently only extends to a few picometers, high optical resolution is ultimately needed to extract useful isotopic information from the recorded emission spectra. Therefore, the concentration of plutonium (Pu) and uranium (U) as well as their isotopic composition can be assessed in nuclear specimens using this instrumental technique. − …”

“…On the basis of our previous experience on the determination of actinides employing HR-ICP-OES, ,− ,− this study aimed at developing and validating an accurate and fast analytical procedure to assess the 234 U/ 238 Pu amount ratio and the eventual calculation of the production date of specific nuclear samples. Among the challenges successfully handled during method development was the isotope-specific quantification of 234 U and 238 Pu using HR-ICP-OES.…”

Atomic spectrometry update: review of advances in the analysis of metals, chemicals and functional materials

“…Finally, the application of a high resolution ICP-OES method to the determination of Pu in samples originating from the nuclear fuel cycle has been described. 165 The exceptionally line-rich concomitant elements such as Am, Np, Th and U can complicate the emission spectrum and consequently much of the study focused on identifying Pu wavelengths that were not interfered with. Forty-three wavelengths were identied of which the most prominent 27 were investigated with respect to their SBR, slope (counts per mg kg À1 ) and line width.…”

High Resolution ICP-OES: a Powerful Diagnostic Tool for Nuclear Forensic Studies

“…Knowledge of the elemental and isotopic composition of a seized radioactive sample is a key parameter in nuclear forensics. While mass spectrometry is used in most instances for obtaining such data, recent developments in high resolution inductively coupled plasma -optical emission spectrometry (HR-ICP-OES) allow for fast and reliable comparative analysis (Krachler et al, 2015;Krachler & Alvarez Sarandes, 2015;Krachler & Alvarez Sarandes, 2016) Employing two instrumental techniques (mass spectrometry and optical emission) based on different physical detection principles, the accuracy of analytical data can be ascertained (Krachler et al, 2015).…”