@misc{oai:repo.qst.go.jp:00086562,
 author = {Hiroshi, Yoshii and Tetsuaki, Uwatoko and Kumiko, Fukutsu and Yasuhiro, Sakai and Hiroshi, Yoshii and Tetsuaki, Uwatoko and Kumiko, Fukutsu and Yasuhiro, Sakai},
 month = {Jun},
 note = {At TEPCO's Fukushima Daiichi Nuclear Power Station, contaminated water is treated after removing radionuclides. Fuel debris removal, which is commencing soon, may discharge water contaminated with actinides, such as uranium, neptunium, and plutonium, requiring screening prior to treatment. In this paper, we propose an actinide screening method based on X-ray fluorescence (XRF) analysis.
In this method, actinides are collected on a chelating disk [1] containing iminodiacetic acid as a chelating agent, and their L-X rays are analyzed using an energy-dispersive XRF device. The Br Kβ, Rb Kα, and Sr Kα peaks overlap with the Lα peaks of U, Np, and Pu, which interferes with the analysis. Of these, the Br Kβ and Rb Kα peaks are located in the lower energy region of the U Lα peak and can be separated by peak fitting [2]. Furthermore, the Sr Kα peak is located between the Np Lα and Pu Lα peaks, hindering its separation by peak fitting owing to the proximity of the peaks. Therefore, before collecting the actinides in the sample solution on the chelating disk, Sr is removed by loading through a Sr Rad Disk [3], which adsorbs Sr well.
First, simulated contaminated water containing Sr was mixed with same amount of 4 mol/L nitric acid and a solution containing 200 ng of U, Np, and Pu. This was loaded through a Sr Rad Disk. To the filtrate, 1 mol/L ammonium acetate were added, and pH was adjusted to 5.6. The chelating disk of 22.5 mm diameter was conditioned with methanol, 2 mol/L nitric acid, ultrapure water, and 0.1 mol/L ammonium acetate solution (pH 5.6). Actinides were collected on the disc by loading the sample solution through chelate discs.
The XRF measurement of the disc was performed using an Epsilon 4 tabletop XRF spectrometer (PANalytical, Malvern Instruments, Spectris plc, England). The X-ray tube voltage and current were set to 50 kV and 0.3 mA, respectively, and the X-ray accumulation time for each spectral measurement was 300 s. In the measured XRF spectrum, the Lα peaks of U, Np, and Pu were clearly observed. In this presentation, we explain the features and benefits of this technique. 
This research project was conducted as a regulatory supporting research funded by the Secretariat of Nuclear Regulation Authority (S/NRA/R) in Japan.
[1] T. Inui et al., X-ray spectrometry 40, 2011, 301–305.
[2] H. Yoshii et al., Spectrochimica Acta B, 189, 2022, 106368.
[3] LL. Smith et al., Radiochemical Acta 73, 1996, 165–170., European Conference on X-ray Spectrometry 2022},
 title = {X-ray Fluorescence Analysis of Actinides Collected from Contaminated Water},
 year = {2022}
}