Analysis and quantification of tritium and other low-level radionuclides present in ALPS-treated water

Shimada, Asako ; Hemmi, Ko ; Ohira, Saki  ; Iida, Yoshihisa 

Advanced-Liquid-Processing-System (ALPS)-treated water was sampled from the K4-B tank group on March 24, 2022, in the presence of staff from the International Atomic Energy Agency (IAEA) and Tokyo Electric Power Company (TEPCO) Holdings, Inc. The Nuclear Safety Research Center (NSRC) of the Japan Atomic Energy Agency analysed 10 key radionuclides (H, C, Co, Sr, Tc, Ru, Sb, I, Cs, and Cs) and three additional nuclides (Cl, Fe, and Se) in the ALPS-treated water as part of independent monitoring for the regulatory body. According to the obtained results, all radionuclide concentrations, except that for H concentration, were ultralow and less than the standard values permitted for discharge. TEPCO's analytical results were evaluated using the En number, which indicated satisfactory performance. Additionally, reference values and scores obtained via the IAEA's interlaboratory comparisons were recalculated incorporating the NSRC's results. All scores for NSRC, IAEA, and TEPCO fell between -2 and 2, demonstrating that the results are acceptable at a 95.4% confidence level.