The effect of soil exchangeable (plant-available) potassium (ExK) content on cesium (Cs) absorption and translocation in buckwheat was evaluated in a field contaminated with radioactive Cs (
134
Cs ...and
137
Cs, RCs) in 2013. The RCs concentration in buckwheat was significantly positively correlated with the naturally occurring stable Cs (
133
Cs, SCs) concentration, and was lower at higher soil ExK content. The RCs and SCs were actively absorbed by buckwheat until the flowering stage. The soil ExK content was significantly negatively correlated with soil exchangeable RCs and SCs (ExRCs and ExSCs) concentrations. Greater RCs and SCs absorption by buckwheat in soils with low ExK contents was mainly due to higher soil ExRCs and ExSCs concentrations. Reproductive organs showed the largest differences in SCs concentration between low-ExK and high-ExK plots. The root-shoot and shoot-reproductive organs translocations of SCs markedly decreased with increasing soil ExK content. In the root-shoot and shoot-reproductive organs translocations, the discrimination of SCs and K decreased with decreasing soil ExK content. Our main findings were as follows: (1) because RCs are mainly taken up at the earlier growth stage, potassium should be applied as a basal fertilizer to decrease the RCs concentration in buckwheat; (2) lower soil ExK content led to higher soil ExRCs concentrations, resulting in greater RCs absorption by buckwheat; (3) the high Cs absorption and translocation and weaker discrimination between Cs and K in low ExK content soil may be due to the expression of K transporter(s) with weak discrimination between Cs and K.
The effects of fission product transmutation on the structural stability of ceramic waste forms are a critical concern due to the changes of valence and ionic size, which can impair the stability of ...the host matrices. In this study, CsxBayTi3+2y+xTi4+8-2y-xO16 (0.3 ≤ x, y ≤ 0.75) ceramics were designed and successfully synthesized to immobilized 137Cs and its daughter product 137Ba. The evolution of phase and microstructure of the hollandite-ceramic waste forms were investigated by the substitution of Ba2+ into the Cs+ site and the incorporation of Ti3+ for charge compensation. The results show that the prepared hollandite ceramics exhibit excellent capacity to accommodate Cs+ and Ba2+ in its lattice while retaining a stable crystalline structure with a compact microstructure. Additionally, all elements of Cs, Ba, Ti and O homogeneously distributed in the sintered hollandite ceramics. These results further indicate that hollandite ceramics are a promising candidate for selective and durable immobilization of radioactive cesium.
Concentrations of 137Cs in seawater, seabed sediment, and pore water collected from the area around Fukushima were investigated from 2015 to 2018, and the potential of coastal sediments to supply ...radiocesium to the bottom environment was evaluated. The 137Cs concentration in the pore water ranged from 33 to 1934 mBq L–1 and was 10–40 times higher than that in the overlying water (seawater overlying within 30 cm on the seabed). At most stations, the 137Cs concentrations in the overlying water and the pore water were approximately proportional to those in the sediment. The conditional partition coefficient between pore water and sediment was 0.9–14 × 102 L kg–1, independent of the year of sampling. These results indicated that an equilibrium of 137Cs between pore water and sediment has been established in a relatively short period, and 137Cs in the pore water is gradually exported to seawater near the seabed. A simple box model estimation based on these results showed that 137Cs in the sediment decreased by about 6% per year by desorption/diffusion of 137Cs from the seabed.
Using the coherent elastic neutrino-nucleus scattering data of the COHERENT experiment, we determine for the first time the average neutron rms radius of ^{133}Cs and ^{127}I. We obtain the ...practically model-independent value R_{n}=5.5_{-1.1}^{+0.9} fm using the symmetrized Fermi and Helm form factors. We also point out that the COHERENT data show a 2.3σ evidence of the nuclear structure suppression of the full coherence.
Estimating the internal thyroid dose received by residents involved in the 2011 Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has been a challenging task because of the shortage of direct ...human measurements related to the largest contributing radioisotope to the dose, I. In a previous dose estimation, we used the results of whole-body counter (WBC) measurements targeting Cs and Cs, based on the assumption that these radioisotopes were incorporated at the same time as I in the early phase of the accident. The main purpose of this study was to clarify whether the trace of the early intake remained in the WBC measurements that were started several months after the accident. In the present work, WBC data of 1,639 persons from Namie town, one of the heavily contaminated municipalities, were analyzed together with their evacuation behavior data. The results demonstrated that the cesium detection rate in the WBC results was several times higher in the late evacuees who evacuated outside the 20-km radius of the FDNPP at 3:00 p.m. (Japanese Local Time) on 12 March or later compared to the prompt evacuees (who evacuated before 3:00 p.m. on 12 March). Among the adults, the cesium detection rates (and the 90th percentile values of the Cs intake) of the prompt and late evacuees were about 20% (5.4 × 10 Bq) and 60% (1.6 × 10 Bq), respectively. Approximately 20% of the individuals analyzed were categorized as late evacuees. These differences in cesium would be caused by exposure to the radioactive plume in the afternoon on 12 March, which was likely to influence the late evacuees. On the other hand, the intake on 15 March, when the largest release event occurred, was expected to be relatively small for Namie town's residents. In conclusion, the trace of the early intake remained in the WBC measurements, although this would not necessarily be true for all subjects. The results obtained from this study would provide useful information for the reconstruction of the early internal thyroid doses from radioiodine in the future.
The spatial pattern of soil redistribution rate was investigated using cesium-137 ( super(137Cs) within a cultivated complex hillslope in western Iran. The relationship between soil redistribution ...rate and soil organic carbon and total nitrogen pattern were studied using co-regionalization analysis. Ninety-one soil cores were sampled for ) super(1)37Cs, total nitrogen, and soil organic carbon measurements. The simplified mass balance model estimated a gross erosion rate of 29.8 t ha super(-1 yr) super(-)1 and a net soil deposition rate of 21.8 t ha super(-1 yr) super(-)1; hence, a net soil loss rate of 8 t ha super(-1 yr) super(-)1. This magnitude of soil erosion rate is higher than the acceptable rate in semiarid regions. Co-regionalization analysis and co-dispersive coefficients among the selected variables showed that only a small fraction of the variability in total nitrogen and soil organic carbon could be explained by soil redistribution and that the remaining might be the result of different management practices by local farmers.
Radioactive Cs-rich microparticles (CsMPs) released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) are a potential health risk through inhalation. Little has been documented on the occurrence ...of CsMPs, particularly their occurrence inside buildings. In this study, we quantitatively analyze the distribution and number of CsMPs in indoor dust samples collected from an elementary school located 2.8 km to the southwest of FDNPP. The school had remained deserted until 2016. Then, using a modified version of the autoradiography-based “quantifying CsMPs (mQCP) method,” we collected samples and determined the number of CsMPs and Cs radioactive fraction (RF) values of the microparticles (defined as total Cs activity from CsMPs/bulk Cs activity of the entire sample). The numbers of CsMPs ranged from 653 to 2570 particles/(g dust) and 296–1273 particles/(g dust) on the first and second floors of the school, respectively. The corresponding RFs ranged between 6.85 – 38.9% and 4.48–6.61%, respectively. The number of CsMPs and RF values in additional outdoor samples collected near the school building were 23–63 particles/(g dust or soil) and 1.14–1.61%, respectively. The CsMPs were most abundant on the school's first floor near to the entrance, and the relative abundance was higher near the stairs on the second floor, indicating a likely CsMP dispersion path through the building. Additional wetting of the indoor samples combined with autoradiography revealed that indoor dusts had a distinct absence of intrinsic, soluble Cs species, such as CsOH. These combined observations indicate that a significant amount of poorly soluble CsMPs were likely contained in initial radioactive airmass plumes from the FDNPP and that the microparticles penetrated buildings. CsMPs could still be abundant at the location, with locally high Cs activity in indoor environments near to openings.
Display omitted
•An elementary school near Fukushima Daiichi was contaminated with radioactive Cs.•Up to 2481 particles/m2 of cesium-rich microparticles (CsMPs) were present indoors.•The radioactive fraction of CsMPs to bulk indoor dust (RF) was as high as 38.9%.•CsMPs were deposited near the school entrances, resulting in localized hot spots.•Initial radioactive plumes in March 2011 delivered considerable amounts of CsMPs.
Metal halide perovskites are promising candidates for room-temperature gamma-ray spectrum detectors; however, it is hard to grow high-quality single crystals that are performance competitive with ...existing materials. Here we report the growth of centimetre-sized formamidinium-caesium lead bromide (FACsPbBr3) single crystals at high yield from low-purity (98%) precursors using a solution method. The introduction of formamidinium into CsPbBr3 reduces defect density in crystals by eliminating the phase transition upon cooling from growth temperature to room temperature. A mixed solvent is applied to match the solubility slopes of CsPbBr3 and FAPbBr3, resulting in successful incorporation of caesium into FAPbBr3 at FA:Cs ratios from 0 to 1. As-grown FACsPbBr3 exhibits a high resistivity of 9.5 × 109 Ω cm, balanced hole and electron mobility-lifetime products of (2.2–3.2) × 10−3 cm2 V−1, and a record low deep trap density of 5.6 × 1010 cm−3, yielding a high charge collection efficiency of 84% under gamma-rays. FACsPbBr3 spectrum detectors achieve an energy resolution of 2.9% for 662 keV 137Cs γ-rays. Over 65% of the FACsPbBr3 crystals exhibit good γ-ray spectral performance. FACsPbBr3 single crystals show excellent stability under large biases of up to 1,000 V and no degradation of spectrum performance after seven months.Centimetre-sized formamidinium-caesium lead bromide (FACsPbBr3) single crystals were grown at high yield from low-purity precursors. High (84%) charge collection efficiency and energy resolution (2.9% for 662 keV 137Cs) for γ-rays were demonstrated.
Efficient and cost-effective removal of radioactive (137)Cs and (90)Sr found in spent fuel is an important step for safe, long-term storage of nuclear waste. Solid-state materials such as resins and ...titanosilicate zeolites have been assessed for the removal of Cs and Sr from aqueous solutions, but there is room for improvement in terms of capacity and selectivity. Herein, we report the Cs(+) and Sr(2+) exchange potential of an ultra stable MOF, namely, MIL-101-SO3H, as a function of different contact times, concentrations, pH levels, and in the presence of competing ions. Our preliminary results suggest that MOFs with suitable ion exchange groups can be promising alternate materials for cesium and strontium removal.
PDF
