"Invisible" radioactive cesium atoms revealed: Pollucite inclusion in cesium-rich microparticles (CsMPs) from the Fukushima Daiichi Nuclear Power Plant.

Understanding radioactive Cs contamination has been a central issue at Fukushima Daiichi and other nuclear legacy sites; however, atomic-scale characterization of radioactive Cs in environmental samples has never been achieved. Here we report, for the first time, the direct imaging of radioactive Cs atoms using high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). In Cs-rich microparticles collected from Japan, we document inclusions that contain 27 - 36 wt% of Cs (reported as CsO) in a zeolite: pollucite.

Microbially formed Mn(IV) oxide as a novel adsorbent for removal of Radium.

Radioactivity of Ra isotopes in natural waters is of serious concern. Control of Ra concentrations in tailings ponds, which store waste from U ore extraction processes, is an important issue in mill tailings management. In this study, we tested microbially formed Mn(IV) oxide as an adsorbent for removal of Ra in water treatment.

Simulant molten core-concrete interaction experiments in view of understanding Fukushima Daiichi Nuclear Power Station Cs-bearing particles generation mechanism.

The Fukushima Daiichi accident resulted in the release of a novel form of radioactive Cs contamination into the environment, called Cs-bearing microparticles (CsMP). CsMPs constitute a substantial portion of the radioactive pollution near the nuclear power station and traveled beyond several hundred kilometers. Extensive characterization of the CsMPs revealed an amorphous silica matrix, along with Cs and other minor or trace elements such as Fe and Zn.

Occurrence of radioactive cesium-rich micro-particles (CsMPs) in a school building located 2.8 km south-west of the Fukushima Daiichi Nuclear Power Plant.

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.

Uranium retention in a Callovo-Oxfordian clay rock formation: From laboratory-based models to in natura conditions.

For the performance assessment of radioactive waste disposal, it is critical to predict the mobility of radionuclides in the geological barrier that hosts it. A key challenge consists of assessing the transferability of current knowledge on the retention properties deduced from model systems to in natura situations. The case of the redox-sensitive element uranium in the Callovo-Oxfordian clay formation (COx) is presented herein.

Volatilization of BC control rods in Fukushima Daiichi nuclear reactors during meltdown: B-Li isotopic signatures in cesium-rich microparticles.

Boron carbide control rods remain in the fuel debris of the damaged reactors in the Fukushima Daiichi Nuclear Power Plant, potentially preventing re-criticality; however, the state and stability of the control rods remain unknown. Sensitive high-resolution ion microprobe analyses have revealed B-Li isotopic signatures in radioactive Cs-rich microparticles (CsMPs) that formed by volatilization and condensation of Si-oxides during the meltdowns. The CsMPs contain 1518-6733 mg kg of B and 11.

Radiocesium in Shiitake mushroom: Accumulation in living fruit bodies and leaching from dead fruit bodies.

In this paper, cesium (Cs) accumulation by the saprophytic fungus Lentinula edodes (Shiitake) was investigated to contribute to the elucidation of radiocesium-cycling mechanisms in forest environments. Although the Cs in the mushroom bed before culture was bioavailable, the transfer factor (TF) of Cs (Cs and Cs) from the mushroom bed to fruit bodies was low (approximately 1) and the TFs of K (5) and Na (1.5) were higher.

New highly radioactive particles derived from Fukushima Daiichi Reactor Unit 1: Properties and environmental impacts.

A contaminated zone elongated toward Futaba Town, north-northwest of the Fukushima Daiichi Nuclear Power Plant (FDNPP), contains highly radioactive particles released from reactor Unit 1. There are uncertainties associated with the physio-chemical properties and environmental impacts of these particles. In this study, 31 radioactive particles were isolated from surface soils collected 3.

Effect of bacterial siderophore on cesium dissolution from biotite.

In this study, the adsorption of cesium (Cs) on biotite and dissolution of Cs from Cs-bearing biotite using a siderophore were investigated aiming to contribute to the elucidation of radiocesium migration mechanisms in the soil environment. Thus, a siderophore was extracted and purified from the culture medium of Pseudomonas sp., and the purified siderophore was used in five consecutive dissolution experiments of biotite samples.

Nickel Retention on Callovo-Oxfordian Clay: Applicability of Existing Adsorption Models for Dilute Systems to Real Compact Rock.

In a waste management context, predicting the mobility of contaminants is essential. A key issue entails assessing the applicability of current knowledge on adsorption processes to natural systems. Such is the focus herein for nickel in interaction with Callovo-Oxfordian (COx) clay rock, a formation selected in France for possible radioactive waste disposal.

An integrated approach combining soil profile, records and tree ring analysis to identify the origin of environmental contamination in a former uranium mine (Rophin, France).

Uranium mining and milling activities raise environmental concerns due to the release of radioactive and other toxic elements. Their long-term management thus requires a knowledge of past events coupled with a good understanding of the geochemical mechanisms regulating the mobility of residual radionuclides. This article presents the results on the traces of anthropic activity linked to previous uranium (U) mining activities in the vicinity of the Rophin tailings storage site (Puy de Dôme, France).

Particulate plutonium released from the Fukushima Daiichi meltdowns.

Traces of Pu have been detected in material released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March of 2011; however, to date the physical and chemical form of the Pu have remained unknown. Here we report the discovery of particulate Pu associated with cesium-rich microparticles (CsMPs) that formed in and were released from the reactors during the FDNPP meltdowns. The Cs-pollucite-based CsMP contained discrete U(IV)O nanoparticles, <~10 nm, one of which is enriched in Pu adjacent to fragments of Zr-cladding.

Thermodynamic data of adsorption reveal the entry of CH and CO in a smectite clay interlayer.

The ability of smectite clays to incorporate gases in their interlayers is shown to be conditioned by interlayer spacing, depending, in turn, on phyllosilicate layer composition and effective size of the charge-balancing cations. As illustrated by earlier in situ X-ray diffraction and spectroscopic characterization of the gas/clay interface, most smectites with small-size charge-balancing cations, such as Na or Ca, accommodate CO and CH in their interlayers only in a partially hydrated state resulting in the opening of the basal spacing, above a certain critical value. In the present study CH and CO adsorption isotherms were measured for Na- and Mg-exchanged montmorillonite up to 9 MPa using a manometric technique.

Abundance and distribution of radioactive cesium-rich microparticles released from the Fukushima Daiichi Nuclear Power Plant into the environment.

The abundance and distribution of highly radioactive cesium-rich microparticles (CsMPs) that were released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) during the first stage of the nuclear disaster in March 2011 are described for 20 surface soils collected around the FDNPP. Based on the spatial distribution of the numbers (particles/g) and radioactive fraction (RF) of the CsMPs in surface soil, which is defined as the sum of the CsMP radioactivity (in Bq) divided by the total radioactivity (in Bq) of the soil sample, three regions of particular interest have been identified: i.) near-northwest (N-NW), ii.

Smectite fraction assessment in complex natural clay rocks from interlayer water content determined by thermogravimetric and thermoporometry analysis.

The smectite content is a key parameter to be determined for various applications of clays and clay-rich rocks. The quantity of interlayer water characteristic of swelling domains can be used to assess the smectite content in clays. We propose in this study to use a simple approach to determine water distribution in clays (mainly between pores and interlayers) by means of thermoporometry and thermogravimetric analysis.

Dissolution of radioactive, cesium-rich microparticles released from the Fukushima Daiichi Nuclear Power Plant in simulated lung fluid, pure-water, and seawater.

To understand the chemical durability of highly radioactive cesium-rich microparticles (CsMPs) released from the Fukushima Daiichi Nuclear Power Plant in March 2011, we have, for the first time, performed systematic dissolution experiments with CsMPs isolated from Fukushima soils (one sample with 108 Bq and one sample with 57.8 Bq of Cs) using three types of solutions: simulated lung fluid, ultrapure water, and artificial sea water, at 25 and 37 °C for 1-63 days. The Cs was released rapidly within three days and then steady-state dissolution was achieved for each solution type.

Size Distribution of Droplets in a Two Liquid-phase Mixture Compared between Liquid Spraying and Mechanical Stirring.

A new liquid-liquid extraction method, called the "emulsion flow" method, is expected to realize an ideal liquid-liquid extraction by controlling the emulsion generation and separation using liquid spraying, only by solution sending. In order to understand the mechanism of emulsion control in the emulsion flow method, the size distribution of droplets in two liquid-phase mixtures was compared by using originally designed apparatuses 1) for the case of liquid spraying and 2) for the case of mechanical stirring. We demonstrated that the size distribution of droplets generated near a mixing device (a nozzle for liquid spraying or an impeller head for mechanical stirring) determines the phase-separation property.

Continuous Liquid-Liquid Extraction of Uranium from Uranium-containing Wastewater Using an Organic Phase-refining-type Emulsion Flow Extractor.

A previously reported emulsion flow (EF) extraction system does not equip the refining device for any used organic phase. Therefore, the processing of large quantities of wastewater by using the EF extractor alone could lead to the accumulation of extracted components into the organic phase, and a lowering of the extraction performance. In the present study, we developed an organic phase-refining-type EF system, which is equipped with a column for refining a used organic phase to prevent accumulation, and successfully applied it for treating uranium-containing wastewater.

Natural organic matter contained in clay rock pore water: Direct quantification at the molecular level using electrospray ionization mass spectrometry.

Rationale: Natural organic matter (NOM) is present in the environment and could influence the migration of heavy metals/radionuclides. The dissolved fraction of NOM (DOM) is usually quantified using total organic carbon analysis or UV-visible spectrometry. Nonetheless, analysis using pattern recognition cannot provide the full spectrum of organic molecules contained in waters, especially low-molecular-weight compounds.

Novel Method of Quantifying Radioactive Cesium-Rich Microparticles (CsMPs) in the Environment from the Fukushima Daiichi Nuclear Power Plant.

Highly radioactive cesium-rich microparticles (CsMPs) were released from the Fukushima Daiichi nuclear power plant (FDNPP) to the surrounding environment at an early stage of the nuclear disaster in March of 2011; however, the quantity of released CsMPs remains undetermined. Here, we report a novel method to quantify the number of CsMPs in surface soils at or around Fukushima and the fraction of radioactivity they contribute, which we call "quantification of CsMPs" (QCP) and is based on autoradiography. Here, photostimulated luminescence (PSL) is linearly correlated to the radioactivity of various microparticles, with a regression coefficient of 0.

Uranium Dioxides and Debris Fragments Released to the Environment with Cesium-Rich Microparticles from the Fukushima Daiichi Nuclear Power Plant.

Trace U was released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) during the meltdowns, but the speciation of the released components of the nuclear fuel remains unknown. We report, for the first time, the atomic-scale characteristics of nanofragments of the nuclear fuels that were released from the FDNPP into the environment. Nanofragments of an intrinsic U-phase were discovered to be closely associated with radioactive cesium-rich microparticles (CsMPs) in paddy soils collected ∼4 km from the FDNPP.

Complexation of Eu(III), Pb(II), and U(VI) with a Paramecium glycoprotein: Microbial transformation of heavy elements in the aquatic environment.

This study investigated the interaction of inorganic aqueous Eu(III), Pb(II), and U(VI) with Paramecium sp., a representative single-celled protozoan that lives in freshwater. Living and prekilled Paramecium cells were tested.

Isotopic signature and nano-texture of cesium-rich micro-particles: Release of uranium and fission products from the Fukushima Daiichi Nuclear Power Plant.

Highly radioactive cesium-rich microparticles (CsMPs) released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) provide nano-scale chemical fingerprints of the 2011 tragedy. U, Cs, Ba, Rb, K, and Ca isotopic ratios were determined on three CsMPs (3.79-780 Bq) collected within ~10 km from the FDNPP to determine the CsMPs' origin and mechanism of formation.

Caesium-rich micro-particles: A window into the meltdown events at the Fukushima Daiichi Nuclear Power Plant.

The nuclear disaster at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011 caused partial meltdowns of three reactors. During the meltdowns, a type of condensed particle, a caesium-rich micro-particle (CsMP), formed inside the reactors via unknown processes. Here we report the chemical and physical processes of CsMP formation inside the reactors during the meltdowns based on atomic-resolution electron microscopy of CsMPs discovered near the FDNPP.

State of Fukushima nuclear fuel debris tracked by Cs137 in cooling water.

It is still difficult to assess the risk originating from the radioactivity inventory remaining in the damaged Fukushima nuclear reactors. Here we show that cooling water analyses provide a means to assess source terms for potential future releases. Until now already about 34% of the inventories of (137)Cs of three reactors has been released into water.