Preparedness for a nuclear accident: removal of radioiodine from soil by chemical processing

Recent Advances in the Removal of Radioactive Iodine and Iodide from the Environment

Iodine (I2) in the form of iodide ions (I-) is an essential chemical element in the human body. Iodine is a nonmetal that belongs to the VIIA group (halogens) in the periodic table. Over the last couple of centuries, the exponential growth of human society triggered by industrialization coincided with the use of iodine in a wide variety of applications, including chemical and biological processes. However, through these processes, the excess amount of iodine eventually ends up contaminating soil, underground water, and freshwater sources, which results in adverse effects. It enters the food chain and interferes with biological processes with serious physiological consequences in all living organisms, including humans. Existing removal techniques utilize different materials such as metal-organic frameworks, layered double hydroxides, ion-exchange resins, silver, polymers, bismuth, carbon, soil, MXenes, and magnetic-based materials. From our literature survey, it was clear that absorption techniques are the most frequently experimented with. In this Review, we have summarized current advancements in the removal of iodine and iodide from human-made contaminated aqueous waste.

Radionuclides in surface waters around the damaged Fukushima Daiichi NPP one month after the accident: Evidence of significant tritium release into the environment

Following the Fukushima nuclear accident (2011), radionuclides mostly of volatile elements (e.g., ¹³¹I, ^134,137Cs, ¹³²Te) have been investigated frequently for their presence in the atmosphere, pedosphere, biosphere, and the Pacific Ocean. Smaller releases of radionuclides with intermediate volatility, (e.g., ⁹⁰Sr), have been reported for soil. However, few reports have been published which targeted the contamination of surface (fresh) waters in Japan soon after the accident. In the present study, 10 surface water samples (collected on April 10, 2011) have been screened for their radionuclide content (³H, ⁹⁰Sr, ¹²⁹I, ¹³⁴Cs, and ¹³⁷Cs), revealing partly unusually high contamination levels. Especially high tritium levels (184 ± 2 Bq·L^-1; the highest levels ever reported in scientific literature after Fukushima) were found in a puddle water sample from close to the Fukushima Daiichi nuclear power plant. The ratios between paddy/puddle water from one location only a few meters apart vary around 1% for ¹³⁴Cs, 12% for ¹²⁹I (¹³¹I), and around 40% for both ³H and ⁹⁰Sr. This illustrates the adsorption of radiocesium on natural minerals and radioiodine on organic substances (in the rice paddy), whereas the concentration differences of ³H and ⁹⁰Sr between the two waters are mainly dilution driven.

Japanese Food Data Challenge the Claimed Link between Fukushima's Releases and Recently Observed Thyroid Cancer Increase in Japan

Internal, high-dose exposure with radioiodine is known to increase the risk for thyroid cancer in children and adolescents. Ingestion of contaminated food is generally regarded a dominant route of internal exposure. We analyzed the huge data set of the post-Fukushima food monitoring campaign and deployed a conservative model for the estimation of the doses to the general public in a worst-case scenario. Our data suggest that the committed equivalent ingestion doses to the thyroids of the affected Japanese public, even in the utmost conservative approach, remained below the limit on ingestion of radioiodine in foodstuffs and beverages of 50 mSv (as thyroid equivalent dose). This level of 50 mSv is also the intervention level for the administration of stable iodine, mainly after inhalation. Our study hence suggests that, based on the food data, the internal exposure of Japanese residents was too low to cause a statistically discernible increase in thyroid cancer, even if the contribution from inhalation is taken into account. The data also indicate that the governmental efforts in the food monitoring campaign were successful and cut the thyroid doses to the public by a factor of approximately 3 compared to a scenario without any monitoring.

A Simple and Rapid Method for Reducing Radiocesium Concentrations in Wild Mushrooms ( Cantharellus and Boletus ) in the Course of Cooking

Many species of mushrooms are known accumulators of radioactive cesium (¹³⁷Cs and ¹³⁴Cs). Even years and decades after major nuclear accidents, especially those at Chernobyl and Fukushima, mushrooms exhibit high concentrations of these radionuclides. We investigated a simple method for reducing the activity of radiocesium in wild mushrooms (chanterelles, Cantharellus cibarius ; and boleti, Boletus edulis ) during cooking. The juice generated while cooking mushrooms contains a relatively high fraction of the total cesium. The amount of juice can be increased by washing the mushrooms with water prior to cooking. By removing the juice, up to 29% of the radiocesium can be easily removed from chanterelles. Because boleti have a lower affinity for cesium, activity levels were lower in boleti than in chanterelles. The fraction of radiocesium in the juice was lower in boleti than in chanterelles.