A: An underwater 137 Cs (662 keV) and 131 I (364 keV) radioisotopes monitoring system has been developed using a 3 × 3 NaI(Tl) detector. To estimate the minimum detectable activity and Bq/L conversion factor, an experiment was first conducted with 68 Ga (511 keV) in a water tank. For energy spectrum comparison, Monte Carlo simulations were performed for 68 Ga, 137 Cs, and 131 I to determine the conversion factor. The minimum detectable 137 Cs and 131 I activities for the system are 0.77 and 0.89 Bq/L, respectively.

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This study aims to utilize Prussian Blue (PB) to develop a high performance adsorbent for removing radioactive cesium from radioactive accidents. Prussian blue (PB) can adsorb selectively to cesium (Cs), which is high in adsorption efficiency, but has a disadvantage that it is difficult to recover after adsorption, so there is a high concern about secondary environmental pollution. Therefore, this study modified the surface of powder activated carbon (PAC) particles by using covalent organic polymer (COP) for stable immobilization of PB, and developed a PB-impregnated adsorbent (COP-PAC-PB). Synthesis of COP-PAC-PB was performed by sequentially reacting with iron (III) chloride and potassium ferrocyanide solution to synthesize PB in COP pore (In-situ). The maximum adsorption of COP-PAC-PB on cesium was 19 mg / g and the removal efficiency for radioactivity cesium (Cs-137, 60 Bq / kg) was 97.3%. In addition, PB was synthesized by the same method as that of COP-PAC-PB, which is a modification product of the unmodified group (PAC, Ox-PAC), and UV-vis analysis was performed to compare PB desorption characteristics after washing Respectively. In the unmodified group (PAC-PB, Ox-PAC-PB), a large amount of PB was desorbed when washed once to 6 times. In the case of COP-PAC-PB, it was not. As a result, the surface of the PAC particles was effectively modified using COP, and the adsorbent with Prussian blue stably immobilized was developed.