The role of trust and risk perception in current German nuclear waste management.

One of the lessons learned in various countries that have to deal with spent nuclear fuel is that finding a proper place and siting a repository for high-level nuclear waste (HLW) cannot be achieved without public consent. After decades of obstruction, Germany recently launched a new, participatory, site-selection process for the disposal of HLW in deep geological formations. Nonetheless, significant opposition is assumed. Therefore, citizens' trust in the procedure and the agents involved may be paramount. We conducted an online survey (N ≈ 5000) in March/April 2020 to test a theoretical model on trust, perceived risks and benefits, and acceptance. We differentiated acceptance as a dependent variable according to distinct phases: the procedure, a possible decision on a disposal location, and the repository facility itself. The results show that trust is mainly important for explaining acceptance of the ongoing procedure and less so for the acceptance of the decision or the repository facility itself. Moreover, our investigation of the sample using a cluster analysis reveals characteristic patterns of trust, risk perception, and acceptance by three clusters: a cluster focusing on risk perception, an ambivalent cluster, and an indifferent cluster. Trust is lowest in the risk-focused cluster and highest in the ambivalent cluster.

The Active Field of Nuclear and Radiochemistry: Not Just Nuclear Power.

" … The number of universities teaching nuclear and radiochemistry has decreased, not least as radiochemistry is erroneously linked to the use of nuclear power … Radiochemistry is essential for a variety of fields, including radiopharmaceuticals, as well as the management of radioactive waste … we are facing a lack of specialists in the area of radiation protection …" Read more in the Editorial by Clemens Walther.

Post-Accident Sporadic Releases of Airborne Radionuclides from the Fukushima Daiichi Nuclear Power Plant Site.

The Fukushima nuclear accident (March 11, 2011) caused the widespread contamination of Japan by direct deposition of airborne radionuclides. Analysis of weekly air filters has revealed sporadic releases of radionuclides long after the Fukushima Daiichi reactors were stabilized. One major discharge was observed in August 2013 in monitoring stations north of the Fukushima Daiichi nuclear power plant (FDNPP). During this event, an air monitoring station in this previously scarcely contaminated area suddenly reported (137)Cs activity levels that were 30-fold above the background. Together with atmospheric dispersion and deposition simulation, radionuclide analysis in soil indicated that debris removal operations conducted on the FDNPP site on August 19, 2013 are likely to be responsible for this late release of radionuclides. One soil sample in the center of the simulated plume exhibited a high (90)Sr contamination (78 ± 8 Bq kg(-1)) as well as a high (90)Sr/(137)Cs ratio (0.04); both phenomena have usually been observed only in very close vicinity around the FDNPP. We estimate that through the resuspension of highly contaminated particles in the course of these earthmoving operations, gross (137)Cs activity of ca. 2.8 × 10(11) Bq has been released.

The radioecological footprint of electricity production by wind turbines.

The worldwide transformation of electricity production goes hand in hand with increasing use of wind energy. The German 'Energiewende' project is no exception and relies heavily on the construction and use of an ever-increasing number of wind turbines. While the operation of wind turbines does not lead to the emission of pollutants (in contrast to, e.g. coal, oil or gas), the production processes of the construction materials do. Since the raw materials' production primarily takes place outside Germany, radioactivity and doses related to these processes occur at remote places in the world. This effect might be called an 'export of doses'. In the present paper, we perform a life cycle analysis of wind turbines, investigating the mining and production of the construction materials. We focus on rare-earth elements needed for the generator magnets and assess the associated releases of radioactive materials during mining and processing, primarily in China. Estimates of dose to the public in selected Chinese cities are calculated. Different electricity generation techniques are compared by the use of the quantity (collective) dose per GW per year.

The chemical journey of Europium(III) through winter rye (Secale cereale L.) - Understanding through mass spectrometry and chemical microscopy.

A combination of biochemical preparation methods with microscopic, spectroscopic, and mass spectrometric analysis techniques as contemplating state of the art application, was used for direct visualization, localization, and chemical identification of europium in plants. This works illustrates the chemical journey of europium (Eu(III)) through winter rye (Secale cereale L.), providing insight into the possibilities of speciation for Rare Earth Elements (REE) and trivalent f-elements. Kinetic experiments of contaminated plants show a maximum europium concentration in Secale cereale L. after four days. Transport of the element through the vascular bundle was confirmed with Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDS). For chemical speciation, plants were grown in a liquid nutrition medium, whereby Eu(III) species distribution could be measured by mass spectrometry and luminescence measurements. Both techniques confirm the occurrence of Eu malate species in the nutrition medium, and further analysis of the plant was performed. Luminescence results indicate a change in Eu(III) species distribution from root tip to plant leaves. Microscopic analysis show at least three different Eu(III) species with potential binding to organic and inorganic phosphate groups and a Eu(III) protein complex. With plant root extraction, further europium species could be identified by using Electrospray Ionization Mass Spectrometry (ESI MS). Complexation with malate, citrate, a combined malate-citrate ligand, and aspartate was confirmed mostly in a 1:1 stoichiometry (Eu:ligand). The combination of the used analytical techniques opens new possibilities in direct species analysis, especially regarding to the understanding of rare earth elements (REE) uptake in plants. This work provides a contribution in better understanding of plant mechanisms of the f-elements and their species uptake.

A teaching concept for school experiments on radioactivity using augmented reality methods.

Digital media are becoming increasingly influential in society, especially among the younger generation. Therefore, an augmented reality (AR) app was developed that simulates experiments with radioactive sources. The app runs experiments on the range and penetration power of alpha, beta and gamma radiation. It assigns virtual radiation sources, shielding materials or a detector to printed image markers, and superimposes their 3D images on the camera image. Alpha, beta and gamma radiation are clearly distinguishable by choosing different visualizations. The detector displays the measured count rates. At school, the app can be used in different ways. A concept for a teaching unit in Grade 10 was developed and tested in several classes based on a prototype of the app. The learning progress from the AR experiments was examined. Furthermore, an evaluation of the app was carried out. The most recent version of the app can be found here: https://seafile.projekt.uni-hannover.de/d/dd033aaaf5df4ec18362/.

Multi-element isotopic analysis of hot particles from Chornobyl.

Microscopic fuel fragments, so-called "hot particles", were released during the 1986 accident at the Chornobyl nuclear powerplant and continue to contaminate the exclusion zone in northern Ukraine. Isotopic analysis can provide vital information about sample origin, history and contamination of the environment, though it has been underutilized due to the destructive nature of most mass spectrometric techniques, and inability to remove isobaric interference. Recent developments have diversified the range of elements that can be investigated through resonance ionization mass spectrometry (RIMS), notably in the fission products. The purpose of this study is to demonstrate the application of multi-element analysis on hot particles as relates to their burnup, particle formation in the accident, and weathering. The particles were analysed with two RIMS instruments: resonant-laser secondary neutral mass spectrometry (rL-SNMS) at the Institute for Radiation Protection and Radioecology (IRS) in Hannover, Germany, and laser ionization of neutrals (LION) at Lawrence Livermore National Laboratory (LLNL) in Livermore, USA. Comparable results across instruments show a range of burnup dependent isotope ratios for U and Pu and Cs, characteristic of RBMK-type reactors. Results for Rb, Ba and Sr show the influence of the environment, retention of Cs in the particles and time passed since fuel discharge.

A new incorporation mechanism for trivalent actinides into bioapatite: a TRLFS and EXAFS study.

One of the most toxic byproducts of nuclear power and weapons production is the transuranics, which have a high radiotoxicity and long biological half-life due to their tendency to accumulate in the skeletal system. This accumulation is inhomogeneous and has been associated with the chemical properties and structure of the bone material rather than its location or function. This suggests a chemical driving force to incorporation and requires an atomic scale mechanistic understanding of the incorporation process. Here we propose a new incorporation mechanism for trivalent actinides and lanthanides into synthetic and biologically produced hydroxyapatite. Time-resolved laser fluorescence spectroscopy and extended X-ray absorption fine structure have been used to demonstrate that trivalent actinides and lanthanides incorporate into the amorphous grain boundaries of apatite. This incorporation site can be used to explain patterns in uptake and distribution of radionuclides in the mammalian skeletal system.

Complexation of europium(III) by bis(dialkyltriazinyl)bipyridines in 1-octanol.

The present work focuses on highly selective ligands for An(III)/Ln(III) separation: bis(triazinyl)bipyridines (BTBPs). By combining time-resolved laser-induced fluorescence spectroscopy, nanoelectrospray ionization mass spectrometry, vibronic sideband spectroscopy, and X-ray diffraction, we obtain a detailed picture of the structure and stoichiometry of the first coordination sphere of Eu(III)-BTBP complexes in an octanolic solution. The main focus is on the 1:2 complexes because extraction studies revealed that those are the species extracted into the organic phase. The investigations on europium(III) complexes of BTBP with different triazin alkylation revealed differences in the formed complexes due to the bulkiness of the ligands. Because of the vibronic sidebands in the fluorescence spectra, we were able to detect whether or not nitrate ligands are coordinated in the first coordination sphere of the Eu-BTBP complexes. In solution, less sterically demanding BTBP offers enough space for additional coordination of anions and/or solvent molecules to form 9-coordinated Eu-BTBP 1:2 complexes, while bulkier ligands tend to form 8-fold-coordinated structures. We also report the first crystal structure of a Ln-BTBP 1:2 complex and that of its 1:1 complex, both of which are 10-coordinated.

Imaging of I, Re and Tc plant uptake on the single-cell scale using SIMS and rL-SNMS.

In radioecological studies, there is a significant need for understanding the plant uptake of radionuclides on a cellular level. The present work applies mass spectrometry to image the radionuclide distribution within the cellular structures of plants at varying concentrations. In a first step, plants of Daucus carota and Pisum sativum labelled with iodine and rhenium were examined, at concentrations in the range of 10 mM. Cross sections of several plant parts were imaged by secondary ion mass spectrometry (SIMS) after cryogenation in order to preserve cell structure. In a second step, the distribution of 99Tc in the two plant species was determined. For radiological reasons, a concentration three orders of magnitude lower was used, rendering measurements with SIMS impossible. Therefore, resonant laser secondary neutral mass spectrometry (rL-SNMS) was used for the first time to image 99Tc with suppression of molecular isobaric interferences. The measurement of only about 1010 atoms of 99Tc atoms is demonstrated and the distribution of 99Tc within a single epidermal cell is imaged.

Ion implantation of 226Ra for a primary 222Rn emanation standard.

Laser resonance ionization at the RISIKO 30 kV mass separator has been used to produce isotopically and isobarically pure and well quantified 222Rn emanation standards. Based upon laser-spectroscopic preparation studies, ion implantation into aluminum and tungsten targets has been carried out, providing overall implantation efficiencies of 40% up to 60%. The absolute implanted activity of 226Ra was determined by the technique of defined solid-angle α-particle spectrometry, where excellent energy resolution was observed. The 222Rn emanation coefficient of the produced targets was studied using α-particle and γ-ray spectrometry, and yielded results between 0.23 and 0.34, with relative uncertainty on the order of 1%. No dependence exceeding a 1% change of the emanation on humidity could be identified in the range of 15 %rH to 75 %rH, whereas there were hints of a slight correlation between the emanation and temperature. Additionally, and as expected, the emanation coefficient was found to be dependent on the target material as well as the implanted dose.

New horizons in microparticle forensics: Actinide imaging and detection of 238Pu and 242mAm in hot particles.

Micrometer-sized pollutant particles are of highest concern in environmental and life sciences, cosmochemistry, and forensics. From their composition, detailed information on origin and potential risks to human health or environment is obtained. We combine secondary ion mass spectrometry with resonant laser ionization to selectively examine elemental and isotopic composition of individual particles at submicrometer spatial resolution. Avoiding any chemical sample preparation, isobaric interferences are suppressed by five orders of magnitude. In contrast to most mass spectrometric techniques, only negligible mass is consumed, leaving the particle intact for further studies. Identification of actinide elements and their isotopes on a Chernobyl hot particle, including 242mAm at ultratrace levels, proved the performance. Beyond that, the technique is applicable to almost all elements and opens up previously unexplored scientific applications.

Survival of the basidiomycete Schizophyllum commune in soil under hostile environmental conditions in the Chernobyl Exclusion Zone.

Radioactive contamination resulting from major nuclear accidents presents harsh environmental conditions. Inside the Chernobyl exclusion zone, even more than 30 years after the accident, the resulting contamination levels still does not allow land-use or human dwellings. To study the potential of basidiomycete fungi to survive the conditions, a field trial was set up 5 km south-south-west of the destroyed reactor unit. A model basidiomycete, the lignicolous fungus Schizophyllum commune, was inoculated and survival in the soil could be verified. Indeed, one year after inoculation, the fungus was still observed using DNA-dependent techniques. Growth led to spread at a high rate, with approximately 8 mm per day. This shows that also white-rot basidiomycetes can survive the harsh conditions in soil inside the Chernobyl exclusion zone. The unadapted fungal strain showed the ability to grow and thrive in the contaminated soil where both stress from radiation and heavy metals were present.

Mycoremediation affects antioxidative status in winter rye plants grown at Chernobyl exclusion zone site in Ukraine.

Soil contaminated with heavy metals in general and radionuclides in particular represents an escalating problem for all living organisms. Since, Chernobyl nuclear power plant accident in 1986 in Ukraine, an exclusion zone of 30 km around the former power plant is uninhabitable land due to severe contamination. Two most notable beta emitters contributing to dose hazards for decades is radioactive 137Cs/90Sr. However, large parts of the zone are also highly contaminated with uranium particles (hot particles) bearing trace amounts of highly alpha-emitting radionuclides. We established an experiment at exclusion zone with the aim to investigate the influence of two macro fungi (Schizophyllum commune (S.C.) and Leucoagaricus naucinus (L.N.)) on oxidative status and antioxidative responses in winter rye plants; from this, we wanted to test the radionuclide/heavy metals retention capacity of both fungi, and probe their further potential for mycoremediation.Result shows some differences in the concentrations of radionuclides/heavy metals and micro/macronutrients uptake in plants. As a biomarker of oxidative status, lipid peroxidation (LPO) levels and other antioxidative parameters were determined, i.e., superoxide-dismutase (SOD) isoenzymes, cysteine (CYS), and ascorbic acid (AA) concentrations as well as catalase (CAT) and glutathione reductase (GR) activities in winter rye shoots. LPO showed no significant differences between controls and plants cultivated with macro fungi. However, CAT activities were elevated in the presence of S.C/L.N compared with control, while GR activity was significantly higher only in presence of S.C. In contrast, isozyme of SOD (Cu,Zn-SOD) was the most prominent in control. Likewise, CYS content was lower in plants grown with both fungi, while AA concentration was only lower in the presence of L.N. The results showed that presence of fungi in radionuclide contaminated soil caused induction of antioxidative response in shoots of winter rye and that the response depended on the type of fungi used.

Uranium accumulation and its phytotoxicity symptoms in Pisum sativum L.

Environmental contamination by uranium (U) and other radionuclides is a serious problem worldwide, especially due to, e.g. mining activities. Ultimate accumulation of released U in aquatic systems and soils represent an escalating problem for all living organisms. In order to investigate U uptake and its toxic effects on Pisum sativum L., pea plantlets were hydroponically grown and treated with different concentrations of U. Five days after exposure to 25 and 50 µM U, P. sativum roots accumulated 2327.5 and 5559.16 mg kg-1 of U, respectively, while in shoots concentrations were 11.16 and 12.16 mg kg-1, respectively. Plants exposed to both U concentrations showed reduced biomass of shoots and reduced content of photosynthetic pigments (total chlorophyll and carotenoids) relative to control. As a biomarker of oxidative stress, lipid peroxidation (LPO) levels were determined, while antioxidative response was determined by catalase (CAT) and glutathione reductase (GR) activities as well as cysteine (Cys) and non-protein thiol (NP-SH) concentrations, both in roots and shoots. Both U treatments significantly increased LPO levels in roots and shoots, with the highest level recorded at 50 µM U, 50.38% in shoots and 59.9% in roots relative to control. U treatment reduced GR activity in shoots, while CAT activity was increased only in roots upon treatment with 25 µM U. In pea roots, cysteine content was significantly increased upon treatment with both U concentrations, for 19.8 and 25.5%, respectively, compared to control plants, while NP-SH content was not affected by the applied U. This study showed significant impact of U on biomass production and biochemical markers of phytotoxicity in P. sativum, indicating presence of oxidative stress and cellular redox imbalance in roots and shoots. Obtained tissue-specific response to U treatment showed higher sensitivity of shoots compared to roots. Much higher accumulation of U in pea roots compared to shoots implies potential role of this species in phytoremediation process.

ECG-gated nonenhanced 3D steady-state free precession MR angiography in assessment of transplant renal arteries: comparison with DSA.

PURPOSE: To evaluate noncontrast material-enhanced steady-state free precession (SSFP) magnetic resonance (MR) angiography in the assessment of transplant renal arteries (RAs) by using digital subtraction angiography (DSA) as the reference standard. MATERIALS AND METHODS: This prospective study was approved by the institutional review board; written informed consent was obtained from all participants. In 20 renal allograft recipients scheduled for DSA, the transplant RAs were assessed with electrocardiographically gated nonenhanced SSFP MR angiography performed at 1.5 T; the degree of stenosis was compared with that of DSA. Subjective image quality for SSFP MR angiography was assessed independently by two radiologists on a four-point scale (from 1, nondiagnostic to 4, excellent) in four predefined segments (I, the iliac artery; II, the main transplant artery; III, segmental branches; and IV, parenchymal branches). Sensitivity, specificity, and accuracy of SSFP MR angiography for the detection of relevant (> or =50%) transplant RA stenosis (TRAS) were calculated on a per-artery basis. RESULTS: One patient was excluded because SSFP MR angiography failed to adequately visualize the allograft vasculature owing to low cardiac output. The mean image quality assessed by both readers was 3.98 +/- 0.16 (standard deviation), 3.5 +/- 0.68, 2.71 +/- 1.12 and 2.03 +/- 1.09 for segments I, II, III, and IV, respectively (kappa = 0.80). DSA helped identify eight relevant (> or =50%) stenoses in six transplant RAs. Kinking of the transplant artery without relevant stenosis was found in seven patients. The degree of stenosis was overestimated in three patients by using SSFP MR angiography. As compared with DSA, the sensitivity, specificity, and accuracy of SSFP MR angiography to help detect relevant TRAS were 100% (six of six), 88% (14 of 16), and 91% (20 of 22), respectively. CONCLUSION: Nonenhanced SSFP MR angiography is a reliable alternative imaging technique for the assessment of transplant RAs in patients for whom contrast-enhanced MR angiography is contraindicated.

Sorption of iodine in soils: insight from selective sequential extractions and X-ray absorption spectroscopy.

The environmental fate of iodine is of general geochemical interest as well as of substantial concern in the context of nuclear waste repositories and reprocessing plants. Soils, and in particular soil organic matter (SOM), are known to play a major role in retaining and storing iodine. Therefore, we investigated iodide and iodate sorption by four different reference soils for contact times up to 30 days. Selective sequential extractions and X-ray absorption spectroscopy (XAS) were used to characterize binding behavior to different soil components, and the oxidation state and local structure of iodine. For iodide, sorption was fast with 73 to 96% being sorbed within the first 24 h, whereas iodate sorption increased from 11-41% to 62-85% after 30 days. The organic fraction contained most of the adsorbed iodide and iodate. XAS revealed a rapid change of iodide into organically bound iodine when exposed to soil, while iodate did not change its speciation. Migration behavior of both iodine species has to be considered as iodide appears to be the less mobile species due to fast binding to SOM, but with the potential risk of mobilization when oxidized to iodate.

Cesium and Strontium Contamination of Nuclear Plant Stainless Steel: Implications for Decommissioning and Waste Minimization.

Stainless steels can become contaminated with radionuclides at nuclear sites. Their disposal as radioactive waste would be costly. If the nature of steel contamination could be understood, effective decontamination strategies could be designed and implemented during nuclear site decommissioning in an effort to release the steels from regulatory control. Here, batch uptake experiments have been used to understand Sr and Cs (fission product radionuclides) uptake onto AISI Type 304 stainless steel under conditions representative of spent nuclear fuel storage (alkaline ponds) and PUREX nuclear fuel reprocessing (HNO3). Solution (ICP-MS) and surface measurements (GD-OES depth profiling, TOF-SIMS, and XPS) and kinetic modeling of Sr and Cs removal from solution were used to characterize their uptake onto the steel and define the chemical composition and structure of the passive layer formed on the steel surfaces. Under passivating conditions (when the steel was exposed to solutions representative of alkaline ponds and 3 and 6 M HNO3), Sr and Cs were maintained at the steel surface by sorption/selective incorporation into the Cr-rich passive film. In 12 M HNO3, corrosion and severe intergranular attack led to Sr diffusion into the passive layer and steel bulk. In HNO3, Sr and Cs accumulation was also commensurate with corrosion product (Fe and Cr) readsorption, and in the 12 M HNO3 system, XPS documented the presence of Sr and Cs chromates.

TRLFS characterization of Eu(III)-doped synthetic organo-hectorite.

Europium(III) was coprecipitated with the clay mineral hectorite, a magnesian smectite, following a multi-step synthesis procedure. Different Eu(III) species associated with the proceeding synthetic hectorite were characterized by selectively exciting the 5D0-->7F0 transition at low temperature (T < 20 K). Fluorescence decay times indicated that Eu(III) ions may be incorporated in the octahedral layer of the brucite precursor as well as in the octahedral sheet of the clay mineral. The excitation spectra indicated that the substitution of the divalent Mg by the trivalent Eu induced local structural deformation. This investigation implements the molecular-level understanding of the f element structural incorporation into the octahedral layer of sheet silicates by coprecipitation with clay minerals from salt solutions at 100 degrees C.