Quantitation of long-lived radionuclide by ICP-MS

Asai, Shiho*; Horita, Takuma

Bunseki Kagaku, 73(10-11), p.569 - 578, 2024/10

The accurate estimation of the quantities and composition of long-lived radionuclides in radioactive waste is crucial for assessing the long-term safety of its disposal. Traditionally, theoretical predictions of the quantities of long-lived radionuclides obtained from burn-up calculation codes with evaluated nuclear data have been used especially for the safety assessment of high-level radioactive waste. However, such nuclear data used in theoretical predictions have not been sufficiently validated due to the scarcity of the reported measurement data. In this study, we aim to contribute to the improvement of the reliability of theoretical predictions by confirming them with the measured quantities of long-lived radionuclides per unit mass of uranium in spent nuclear fuel, which are output data obtained from the burnup calculation code. This involves measuring the long-lived radionuclides present in nuclear fuel pellets used in commercial nuclear reactors. Specifically, we focused on Zr, Pd, and Cs, which can be effectively measured using an inductively coupled plasma mass spectrometer (ICP-MS). Besides the purpose of validating the nuclear data, this article also highlights viable measurement techniques for these radionuclides, along with examples demonstrating their applicability to long-lived radionuclides, including the preparation procedures for their measurement.

Development of a quantification method for Zr isotopes in solid samples by LA-ICP-MS for rapid analysis of Zr-93 in high-level radioactive wastes

Morii, Shiori; Yomogida, Takumi; Asai, Shiho*; Ouchi, Kazuki; Oka, Toshitaka; Kitatsuji, Yoshihiro

Bunseki Kagaku, 72(10.11), p.441 - 448, 2023/10

https://doi.org/10.2116/bunsekikagaku.72.441

Rapid analytical method for the determination of Zr-93 in radioactive wastes has been developed. Laser ablation (LA)-ICP-MS was applied to the analysis of Zr isotopes in simulated high-level radioactive waste (HLW). Sample preparation time was dramatically reduced by using a DGA resin as the adsorbent for Zr. Direct quantification of Zr isotopes in this resin sample was carried out by LA-ICP-MS. Laser settings were optimized to obtain a reliable isotope ratio of the sample by LA-ICP-MS. Quantification of Zr isotopes in the simulated HLW solution by isotope dilution mass spectrometry (IDMS) was examined. The amount of Zr-90 in the sample obtained by IDMS corresponded to a value calculated from the given concentration of Zr in the sample within uncertainty. Thus, this method can be applied for the quantification of Zr-93 in radioactive wastes.

Direct quantitation of Cs in spent Cs adsorbent used for the decontamination of radiocesium-containing water by laser ablation inductively coupled plasma mass spectrometry

Asai, Shiho*; Ohata, Masaki*; Hanzawa, Yukiko; Horita, Takuma; Yomogida, Takumi; Kitatsuji, Yoshihiro

Analytical Chemistry, 92(4), p.3276 - 3284, 2020/02

https://doi.org/10.1021/acs.analchem.9b05161

The long-term safety assessment of spent Cs adsorbents produced during the decontamination of radiocesium-containing water at the Fukushima Daiichi Nuclear Power Plant requires one to estimate their Cs content prior to final disposal. Cs is usually quantified by inductively coupled plasma mass spectrometry (ICP-MS), which necessitates the elution of Cs from Cs adsorbents. However, this approach suffers from the high radiation dose from Cs. To address this challenge, we herein employed laser ablation ICP-MS for direct quantitation of Cs in Cs adsorbents and used a model Cs adsorbent prepared by immersion of a commercially available Cs adsorbent into radiocesium-containing liquid waste to verify the developed technique. The use of the Cs/Cs ratio and Cs radioactivity obtained by gamma spectrometry achieved simple and precise quantitation of Cs and the resulting Cs activity of 0.36 Bq agreed well with that in the original radiocesium-containing liquid waste.

Rapid separation of zirconium using microvolume anion-exchange cartridge for Zr determination with isotope dilution ICP-MS

Asai, Shiho; Hanzawa, Yukiko; Konda, Miki; Suzuki, Daisuke; Magara, Masaaki; Kimura, Takaumi; Ishihara, Ryo*; Saito, Kyoichi*; Yamada, Shinsuke*; Hirota, Hideyuki*

Talanta, 185, p.98 - 105, 2018/08

https://doi.org/10.1016/j.talanta.2018.03.026

Estimating the risks associated with radiation from long-lived fission products (LLFP) in radioactive waste is essential to ensure the long-term safety of potential disposal sites. In this study, the amount of Zr, a LLFP, was determined by ICP-MS after separating Zr from a spent nuclear fuel solution using a microvolume anion-exchange cartridge (TEDA cartridge). The TEDA cartridge achieved highly selective separation of Zr regardless of its small bed volume of 0.08 cm. The time taken to complete the Zr separation was 1.2 min with a flow rate of 1.5 mL/min, which was 10 times faster than that for a conventional anion-exchange resin column. Almost all the other elements were removed, leading to accurate measurement of Zr. The result connects experimental value to theoretical prediction provided by ORIGEN2, which requires verification. With the measured value, we demonstrated that the theoretical value is reliable enough to estimate radiation risks.

Recovery of rare metals using nucleic acid bases and extractants immobilized by grafted polymer chains

Saito, Kyoichi*; Asai, Shiho

Bunseki Kagaku, 66(11), p.771 - 782, 2017/11

https://doi.org/10.2116/bunsekikagaku.66.771

Recovery and purification of rare metals, which are essential ingredients for highly functional materials, generally comes with operational difficulty. In this study, we have developed polymer adsorbents specially designed for highly-efficient adsorption of rare metal ions and exhibited their practical adsorption performances. Radiation-induced graft polymerization, one of the effective modification techniques for polymers, was employed for preparing the proposed adsorbents. Among such adsorbents, a 6-nylon fiber with nucleic-acid base, adenine, on the surface of the fiber demonstrated specific adsorption of ruthenium and palladium ions. In addition, a 6-nylon fiber with an extractant HDEHP (bis (2-ethylhexyl) phophoric acid) that has high affinity for lanthanides, achieved higher separation speed than a commercially available HDEHP-impregnated resin.

Preparation of solid phase extraction cartridges for trace analysis of radionuclides

Asai, Shiho; Saito, Kyoichi*

Biomedical Research on Trace Elements, 28(1), p.1 - 10, 2017/04

Radionuclides are commonly determined with radiometry and mass spectrometry. For -emitting nuclides, the activities can be measured without chemical separation due to the strong penetration ability. In contrast, the measurements of alpha and beta-emitting nuclides are generally associated with tedious and time-consuming chemical separation procedures to remove concomitants. Thus, an adsorbent that achieves rapid separation is desirable to reduce separation time and workload. Our research team has developed compact cartridge-type solid phase extraction materials which enable to facilitate separation procedures. In this review, basic separation performances of the developed cartridges were overviewed along with two application examples to radionuclide-containing samples.

Preparation of Sr adsorptive fiber by impregnating with crown ether derivative for Sr measurement

Horita, Takuma; Asai, Shiho; Konda, Miki; Hanzawa, Yukiko; Saito, Kyoichi*; Fujiwara, Kunio*; Sugo, Takanobu*; Kitatsuji, Yoshihiro

Bunseki Kagaku, 66(3), p.189 - 193, 2017/03

https://doi.org/10.2116/bunsekikagaku.66.189

A Sr-selective adsorption fiber was prepared for rapid analysis of Sr content by using radiation-induced emulsion graft polymerization and subsequent chemical modification. A polyethylene fiber with a diameter of 13 m was first immersed in a methanol solution of an epoxy-group-containing vinyl monomer, glycidyl methacrylate (GMA), and polyoxyethylene sorbitol ester (Tween20) as a surfactant for graft-polymerization of GMA. Octadecylamine was then bound to a polymer chain extending from the fiber surface providing hydrophobicity to the polymer chain. Dicyclohexano-18-crown-6 (DCH18C6) was finally impregnated onto the polymer chain via a hydrophobic interaction between the octadecyl moiety of the polymer chain and the cyclohexyl moiety of DCH18C6. The fiber surface structure, characterized by DCH18C6 molecules loosely entangled with polymer chains, afforded realizes the rapid and selective adsorption of Sr ions with an adsorption rate approximately 100 times higher than that of a commercially available Sr-selective resin (Sr Resin).

Preparation of Zr-91 stable isotope standard solution for determination of Zr-93 by mass spectrometry

Konda, Miki; Asai, Shiho; Hanzawa, Yukiko; Magara, Masaaki

JAEA-Technology 2015-054, 22 Pages, 2016/03

JAEA-Technology-2015-054.pdf:3.44MB

Isotope dilution mass spectrometry (IDMS) with ICP-MS is reliable method for determination of Zr-93, which is one of the long-lived fission products found in spent nuclear fuel and high-level radioactive wastes. In order to use an isotope standard solution of zirconium as the spike for IDMS, dissolving a commercially available solid isotope standard is indispensable. Prior to the dissolution of the Zr-91 isotope standard, solubility of metal zirconium in a mixture of HNO and HF was evaluated using zirconium metal chips. Then, 2 mg of the Zr-91 isotope standard was dissolved with 0.2 mL of 1 M HNO-3 v/v% HF mixed solution, followed by adjusting the concentration of Zr-91 to approximately 1,000 g/g. IDMS, in which a natural isotopic abundance standard solution of zirconium was used as the spike, was employed for the determination of the concentration of Zr-91 in the prepared Zr-91 isotope standard solution. The concentration of Zr-91 in the prepared Zr-91 isotope standard solution was (9.61.0) 10 g/g, which is in good agreement with the predicted concentration. This indicates that the Zr-91 metal isotope standard was completely dissolved with sufficient chemical stability. Additionally, no impurities were detected in the prepared Zr-91 isotope standard solution. These positive results denote that the Zr-91 isotope standard solution with the preferable quality for IDMS of Zr-93 can be obtained by the proposed dissolution procedures.

LA-ICP-MS of rare earth elements concentrated in cation-exchange resin particles for origin attribution of uranium ore concentrate

Asai, Shiho; Limbeck, A.*

Talanta, 135, p.41 - 49, 2015/04

https://doi.org/10.1016/j.talanta.2014.12.009

A new analytical method for chondrite-normalized Rare earth elements (REE) plot has been developed in this study. Cation-exchange resin particles were used as a substrate to retain REE for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In LA analysis, formation of oxide and hydroxide of the light REE and Ba which causes spectral interferences in the heavy REE measurement was effectively attenuated, compared to conventional solution nebulization ICP-MS. To evaluate the applicability of the proposed method, the REE-adsorbed particles prepared by immersing them in a U-bearing solution were measured with LA-ICP-MS. Additionally, each concentration of REE in the U standard solution was determined with solution nebulization ICP-MS. The chondrite-normalized plot obtained through LA-ICP-MS analysis exhibited close agreement with that obtained through the solution nebulization ICP-MS of the REE-separated solution within the uncertainties.

Application of capillary electrophoresis with laser-induced fluorescence detection for the determination of trace neodymium in spent nuclear fuel using complexation with an emissive macrocyclic polyaminocarboxylate probe

Haraga, Tomoko; Saito, Shingo*; Sato, Yoshiyuki; Asai, Shiho; Hanzawa, Yukiko; Hoshino, Hitoshi*; Shibukawa, Masami*; Ishimori, Kenichiro; Takahashi, Kuniaki

Analytical Sciences, 30(7), p.773 - 776, 2014/07

https://doi.org/10.2116/analsci.30.773

A simple and rapid method with low radiation exposure risk was developed for the determination of neodymium in spent nuclear fuel by CE with LIF detection using a fluorescent ligand having a macrocyclic hexadentate polyaminocarboxylate structure. The concentration of Nd(III) in a spent nuclear fuel sample was determined with no interference from various matrix elements, including lanthanides and uranium (at a 200-fold excess), with 92 3% recovery. This is due to method's high resolution based on establishing a ternary complex equilibrium during migration in which the hydroxyl ion plays an auxiliary role.