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The evaluation of fissile mass inside radioactive waste drums is essential for radioactive waste management, nuclear safety, and criticality issues. However, passive and active neutron measurements can be strongly impacted by the uncertainty on the neutron source position within the drum and by matrix attenuation effects. Therefore, an imaging panel proposed by Proportional Technologies Inc., composed of seven Boron-coated straw (BCS) detectors has been tested to localize neutron interactions, in view to reduce uncertainties associated with plutonium or uranium position inside radioactive waste drums. A numerical model of the imaging panel has been developed and validated from a comparison with experimental profiles obtained with a 252Cf source. A passive measurement system equipped with 12 such imaging panels has been designed by numerical simulation, in view to provide information on neutron source location in a 118-L radioactive waste drum filled with organic, metallic, or mixed organic–metallic matrices. Additionally, an experimental setup dedicated to active measurements with a D-T neutron generator has been implemented to test the imaging panel. Prompt fission neutron signals have been recorded, which is induced by thermal interrogating neutrons in fissile material samples. This article presents 2-D images indicating the position of fissile materials. Consequently, BCS imaging panels open interesting prospects to reduce the uncertainty associated with plutonium or uranium localization both in passive and active neutron measurements. [ABSTRACT FROM AUTHOR]

Natural radioactivity in the environment is a field gaining more attention in last decades. This work is focused on the study of natural radioactivity complemented with elementary characterization at former non-uraniferous mining areas in Sweden. This aim is addressed through the study of mining lakes, called pit lakes, which are water bodies generated after opencast mining. Environmental matrices (water, sediments and rocks) from 32 Swedish pit lakes, commonly used for recreational purposes were radiometrically characterized via alpha (238U, 234U, 232Th, 230Th, 210Po isotopes) and gamma spectrometry (238U and 232Th series radionuclides). Additionally, ambient dose rate equivalent in the immediate surrounding of each pit lake was quantified. Physico-chemical parameters (pH, specific conductivity, dissolved oxygen, oxidation–reduction potential) and elemental composition (major and trace elements by ICP-MS) were analysed in water samples and elementary composition of sediments/rocks was measured by XRF and SEM–EDX in some specific cases. A non-negligible number of pit lakes (26%) with enhanced U levels in water was found. At some sites, rocks contained up to 4% of U in areas with high degree of interaction with local population. Concerning the elementary perspective, another popular site (due to its turquoise water) was found to have elevated dissolved heavy metal levels. Results obtained in this work prove that measurement of natural radioactivity is another component that should be included in routine analysis of characterization in mining areas, especially if restauration of post-mining sites is intended for human recreational. [ABSTRACT FROM AUTHOR]

Linear complementary dual (LCD) cyclic codes were referred historically to as reversible cyclic codes, which had applications in data storage. Due to a newly discovered application in cryptography, there has been renewed interest in LCD codes. In particular, it has been shown that binary LCD codes play an important role in implementations against side-channel attacks and fault injection attacks. In this paper, we first present a new characterization of binary LCD codes in terms of their orthogonal or symplectic basis. Using such a characterization, we solve a conjecture proposed by Galvez et al. on the minimum distance of binary LCD codes. Next, we consider the action of the orthogonal group on the set of all LCD codes, determine all possible orbits of this action, derive simple closed formulas of the size of the orbits, and present some asymptotic results on the size of the corresponding orbits. Our results show that almost all binary LCD codes are odd-like codes with odd-like duals, and about half of $q$ -ary LCD codes have orthonormal basis, where $q$ is a power of an odd prime. [ABSTRACT FROM AUTHOR]

Melting of metallic waste reduces the waste volume, allows more accurate radiological characterization, and minimizes handling at the waste production site. This paper proposes a new non-destructive assay methodology to radiologically characterize low- and intermediate-level (LILW) waste before melting. A non-destructive assay technique is developed and qualified using geometry optimization technique and sample analysis after melting. Additionally, we present an operational methodology to predict the activity values of the major gamma emitters based on the average dose rate measurements. • Waste volume reduction via melting allows more accurate characterization. • A new NDA methodology to characterize solid metallic waste before melting. • Qualify uniform activity NDA using geometry optimization and sample analysis. • A methodology that predicts the total beta-gamma activity based on the average dose. [ABSTRACT FROM AUTHOR]

Automated sample processing techniques are desirable in radiochemical analysis for environmental radioactivity monitoring, nuclear emergency preparedness, nuclear waste characterization and management during operation and decommissioning of nuclear facilities, as well as medical isotope production, to achieve fast and cost-effective analysis. Dynamic flow based approaches including flow injection (FI), sequential injection (SI), multi-commuted flow injection (MCFI), multi-syringe flow injection (MSFI), multi-pumping flow system (MPFS), lab-on-valve (LOV) and lab-in-syringe (LIS) techniques have been developed and applied to meet the analytical criteria under different situations. Herein an overall review and discussion on these techniques and methodologies developed for radiochemical separation and measurement of various radionuclides is presented. Different designs of flow systems with combinations of radiochemical separation techniques, such as liquid−liquid extraction (LLE), liquid−liquid microextraction (LLME), solid phase extraction chromatography (SPEC), ion exchange chromatography (IEC), electrochemically modulated separations (EMS), capillary electrophoresis (CE), molecularly imprinted polymer (MIP) separation and online sensing and detection systems, are summarized and reviewed systematically.

Abstract A novel luminescent metal-organic framework has been synthesized, which feathers a 4-connected node 3D network topology. The complex shows an emission peak position change with the increase of solvent polarity. And then,the compound has a good response to the nitro-compounds. Graphical abstract A novel luminescent metal-organic framework, [Cd 2 L(DMF) 2 (H 2 O) 2 ] n (1), based on a chiral binaphthol derivative 2,2′-diethoxy-1,1′binaphthyl-4,4′,6,6′-tetracarboxylic acid (H 4 L) has been synthesized. This compound is a 4-connected node 3D network topology with the point symbol {6^6} and SQC topology type. Photoluminescence (PL) studies indicated that the fluorescence emission peak of complex 1 shows a blue-shift first and then a red-shift with the increase of solvent polarity. Significantly, complex 1 has a good response to the nitro-compounds and its quenching efficiency increases significantly with increasing number of gen-containing groups on explosives. Unlabelled Image Highlights • A novel luminescent metal-organic framework has been obtained. • The framework shows a 4-connected node 3D network topology. • The complex has an emission peak position change with the increase of solvent polarity. • The complex shows a good response to nitro-explosives. [ABSTRACT FROM AUTHOR]

Nuclear materials characterization in 870 L cemented waste drums is challenging due to significant neutron and gamma ray attenuation. Among the existing non-destructive approaches, photon active interrogation is of particular interest. A LINAC accelerates electrons to energies greater than 10 MeV, leading to highly penetrating interrogating bremsstrahlung photons that can reach nuclear materials in the depth of the 870 L waste drum and allow the detection of delayed gamma rays emitted by photofission products. Because the interrogating photon and neutron fluxes are extremely high during irradiation, measurements with high purity germanium detectors are usually performed after a long irradiation time, for example by moving the detector or the waste drum. Therefore, such measurements are only sensitive to delayed gamma rays associated to photofission products having sufficient long half-life of at least tens of seconds, which cuts a valuable signal coming from fission products with a shorter half-life. In this paper, we report gamma rays measurements of very short lived photofission products using a 3 in × 3 in cylindrical LaBr 3 (Ce) fast scintillation detector. A depleted uranium sample was irradiated by a pulsed bremsstrahlung source with maximum energy 17.5 MeV in a macro pulsing mode (1 s irradiation, 2 s cooling). This allowed to acquire a strong delayed gamma signal within a time window of 2 s. A clear signature of nuclear materials was observed even in the depth of a concrete mock-up, with an excellent signal-to-noise ratio beyond 3.5 MeV where the background of nonnuclear activated materials is negligible. These results are compared to a semi analytical model that qualitatively agrees but underestimates the measurements by a constant factor 1.7, probably caused by a wrong beam intensity normalization. Indeed, in this work the LINAC pulse time structure (macro pulsing) was different from its nominal working point used to characterize the beam (usual pulsing mode). Since it allows direct calculations of the detector response to delayed gamma-ray photofission measurements, this model is a fast calculation alternative to time-consuming Monte Carlo simulations, in view of further studies that will follow this feasibility demonstration. [ABSTRACT FROM AUTHOR]

This paper reports a feasibility study of 235 U and 239 Pu characterization in 225 L bituminized waste drums or 200 L concrete waste drums, by detecting delayed fission gamma rays between the pulses of a deuterium-tritium neutron generator. The delayed gamma yields were first measured with bare samples of 235 U and 239 Pu in REGAIN, a facility dedicated to the assay of 118 L waste drums by Prompt Gamma Neutron Activation Analysis (PGNAA) at CEA Cadarache, France. Detectability in the waste drums is then assessed using the MCNPX model of MEDINA (Multi Element Detection based on Instrumental Neutron Activation), another PGNAA cell dedicated to 200 L drums at FZJ, Germany. For the bituminized waste drum, performances are severely hampered by the high gamma background due to 137 Cs, which requires the use of collimator and shield to avoid electronics saturation, these elements being very penalizing for the detection of the weak delayed gamma signal. However, for lower activity concrete drums, detection limits range from 10 to 290 g of 235 U or 239 Pu, depending on the delayed gamma rays of interest. These detection limits have been determined by using MCNPX to calculate the delayed gamma useful signal, and by measuring the experimental gamma background in MEDINA with a 200 L concrete drum mock-up. The performances could be significantly improved by using a higher interrogating neutron emission and an optimized experimental setup, which would allow characterizing nuclear materials in a wide range of low and medium activity waste packages. [ABSTRACT FROM AUTHOR]

A MCNPX model of a neutron activation facility for radioactive waste characterization was built to support experimental studies. To validate this model, small samples of different elemental composition were irradiated and experimental data are compared to simulation results obtained using different neutron capture prompt gamma ray databases. The different databases employed lead to similar results. Simulated and measured net peak areas agree within ±20 %. [ABSTRACT FROM AUTHOR]

The present paper uses a novel approach and aims to assess the efficiency of composite permeable reactive barriers (PRBs) containing organic material and elemental sulphur for the clean-up of leachates containing Cr(VI) and acetate.The paper also aims to identify the main mechanisms involved in the removal of Cr(VI). Experiments were carried out in laboratory plexiglas columns, with a diameter of 5 cm and length of 50 cm. The feed contained 10 mg L−1Cr(VI) and chemical oxygen demand (0.6 or 6 g L−1).Under the optimum experimental set-up, the PRB exhibited over a period of 270 d excellent Cr(VI) decontamination potential. X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry as well as Fourier transform infrared spectroscopy were used to characterize the exhausted reactive material, identify newly formed mineral phases and elucidate Cr(VI) removal mechanisms. Sorption of the reduced Cr(III) on the organic material as well as precipitation, mainly as Cr(OH)3, are the main Cr(VI) removal mechanisms. [ABSTRACT FROM PUBLISHER]

ENTRAP comprises a pan-European cooperation of leading scientific institutions and regulatory bodies in the field of nuclear-waste characterization and its quality assurance for the safe disposal of radioactive waste. Here, the scope of this cooperation is presented and explained and links or interfaces for a potential collaboration with partners fulfilling tasks of IDG-TP are pursued. [ABSTRACT FROM AUTHOR]

The applicability of LaBr-detectors for the non destructive characterization of radioactive waste drums is evaluated by comparing their performance with those of HPGe-detectors. It is shown, that relevant easy-to-measure key-nuclides are identified as well as quantified with a LaBr-detector even in complex spectra at nearly the same level of precision and reliability than with HPGe-detectors. [ABSTRACT FROM AUTHOR]

The mass concentration of carbonaceous species, organic carbon (OC), and elemental carbon (EC) using a semicontinuous thermo-optical EC-OC analyzer, and black carbon (BC) using an Aethalometer were measured simultaneously at an urban mega city Delhi in Ganga basin from January 2011 to May 2012. The concentrations of OC, EC, and BC exhibit seasonal variability, and their concentrations were ∼2 times higher during winter (OC 38.1 ± 17.9 μg m, EC 15.8 ± 7.3 μg m, and BC 10.1 ± 5.3 μg m) compared to those in summer (OC 14.1 ± 4.3 μg m, EC 7.5 ± 1.5 μg m, and BC 4.9 ± 1.5 μg m). A significant correlation between OC and EC ( R = 0.95, n = 232) indicate their common emission sources with relatively lower OC/EC ratio (range 1.0-3.6, mean 2.2 ± 0.5) suggests fossil fuel emission as a major source of carbonaceous aerosols over the station. On average, mass concentration of EC was found to be ∼38 % higher than BC during the study period. The measured absorption coefficient (b) was significantly correlated with EC, suggesting EC as a major absorbing species in ambient aerosols at Delhi. Furthermore, the estimated mass absorption efficiency (σ) values are similar during winter (5.0 ± 1.5 m g) and summer (4.8 ± 2.8 m g). Significantly high aerosol loading of carbonaceous species emphasize an urgent need to focus on air quality management and proper impact assessment on health perspective in these regions. [ABSTRACT FROM AUTHOR]

Abstract: The Radioactive Waste Management Department from IFIN-HH, Bucharest, performs the conditioning of the institutional radioactive waste in concrete matrix, in 200l drums with concrete shield, for final disposal at DNDR – Baita, Bihor county, in an old exhausted uranium mine. This paper presents a gamma-ray spectrometry method for the characterization of the radioactive waste drums' radionuclides content, for final disposal. In order to study the accuracy of the method, a similar concrete matrix with Portland cement in a 200l drum was used. [Copyright &y& Elsevier]

The radionuclides in reactor and fuel construction parts of the V1 Jaslovske Bohunice nuclear power plant (NPP V1) were identified and their activity was measured. Samples from reactor and fuel assemblies such as control rod connection rod, shielding/absorber parts of fuel rod, neutron in-core measurement channels, pressure vessel basic construction material and internal cladding, core barrel and protective tube unit were analyzed. Activity concentrations of Co, Fe, Ni, Sr, Tc, Mo, Nb, transuranic elements were determined. Analytical and sampling methods are briefly described for the measured radionuclides. The presented results were used for characterization of the waste during the decommissioning of NPP V1 nuclear reactors. [ABSTRACT FROM AUTHOR]

Results of difficult to measure radionuclides in primary circuit facilities of nuclear power plant V1 in Jaslovske Bohunice (NPP V1) are presented. Samples from steam generator, main circulation pump and pressurizer were analyzed. Activity concentrations of 55Fe, 63,59Ni, 90Sr, 99Tc, 93Mo, 94Nb, transuranic elements were determined. Analytical and sampling methods are briefly described for the determination of difficult to measure radionuclides. The presented results have been successfully used for characterization of the waste during the decommissioning of NPP V1 nuclear reactors. [ABSTRACT FROM AUTHOR]

The effect of fly ash as a filler for an ESBR-based compound was studied in the range 0-80 phr. Characterization of fly ash, as received, revealed the abundance of 200 mesh size particles with an average diameter of 10 μm; composition analysis showed the predominance of silica and alumina. The properties of ESBR compounds filled with fly ash particles of ⩽200 mesh were compared with those of clay- and whiting-filled compounds. The cure rate index remained unchanged for fly ash throughout the range of loading studied here; clay showed a lower cure rate, and whiting showed a higher value than fly ash. The 300% modulus values did not show any improvement with increase in fly ash loading, the values being comparable with those for whiting and inferior to those for clay. Fly ash gives the lowest heat build-up and tan delta (at 70°C) values among the three fillers under discussion. [ABSTRACT FROM AUTHOR]

All classes of clay minerals absorb water, but the smectite absorb much larger volumes than the other classes because of its expanded network. During the drilling of oil wells it is common for the detection of layers consisting of clay minerals high grade of hydration arranged in laminar packages. When in contact with water, the packets are separated clay as the water enters the basal spacing. This phenomenon is known as expansion or swelling. Given this, this paper aims to characterize shales in two regions of the country to explain the susceptibility of hydration of each of these formations. The characterization was done by making use of Exchange cation capacity (ECC), X-ray fluorescence (XRF), diferential thermal analysis (DTA), Thermogravimetry (TGA) and X-ray diffraction (XRD). The results obtained showed that among the shales studied, those with the greatest degree of clay fractions (smectite) in its composition showed higher swelling index according to the methodology of Foster. [ABSTRACT FROM AUTHOR]

Radioactive waste is any radioactive source or any object contaminated with radionuclide's, which is not foreseen for further use. This waste arises from a number of activities involving the use of radioactive material. The classification of the radioactive waste as general rule is based in their long term safe management. From the other part classification of the radioactive waste is necessary to provide a common base for development of the different aspects related with its conceptual and operational level, technical management, communication and other issues. The classification scheme is mainly based on safety considerations for the lifetime of the waste and can be applied for all waste management practices such as segregation, treatment, conditioning, interim storage and final disposal. A conceptual illustration of the waste classification scheme we presented in figure, and shows the waste classes into which different types of sealed radioactive sources described in Table, the criteria for exempted radioactive materials are defined in IAEA Basic Safety Standards. The radioactive waste that is generated into mentioned practices varied in form, activity concentration and type of contamination as it is in type of generating action. [ABSTRACT FROM AUTHOR]

Abstract: Segmented -scanning (SGS) is the most widely applied technique to non-destructively reconstruct the isotope specific activity content in radioactive waste drums. Around 25% of all radioactive waste drums at the Forschungszentrum Jülich exhibit a homogeneous matrix distribution and activity distribution. Due to these conditions, a numerical method is derived, which largely enhances the accuracy and reliability of the activity reconstruction in comparison to the common analytical method by avoiding various simplifications in the calculations. The numerical method is validated with GEANT4 simulations of reference drums containing the isotopes 137Cs and 60Co. The activities, which are reconstructed with the numerical method in waste matrices with a density range from 0.5gcm−3 to 2.3gcm−3 show systematic deviations of around −2.1% and 4.0% in case of 137Cs and 60Co, respectively. These results show a significant improvement in accuracy compared to the analytical method revealing systematic deviations of around 14.8% and 23.2%, respectively. These results are confirmed by the reconstruction of the activity content in a reference drum from SGS measurements. Uncertainties calculated in the numerical method are halved in comparison to the analytical method. Thus, the reliability of the reconstructed activities is enhanced. [Copyright &y& Elsevier]

The French Alternative Energies and Atomic Energy Commission (CEA) and National Radioactive Waste Management Agency (ANDRA) are conducting an R&D program to improve the characterization of long-lived and medium-activity (LL-MA) radioactive waste packages with analytical methods and with non-destructive nuclear measurements. This paper discusses fast neutron interrogation with the associated particle technique (APT), which provides 3D information about the waste material composition. The characterization of volume elements filled with iron, water, aluminium and PVC in bituminized and fibre concrete LL-MA waste packages has been investigated with MCNP refid="ref1"/ and MODAR data analysis software refid="ref2"/ . APT provides useful information about major elements present in the volumes of interest. However, neutron scattering (especially on hydrogen nuclei) spreads the tagged neutron beam out of the targeted volume towards surrounding materials, reducing spatial selectivity. Simulation shows that targets smaller than 1 L can be characterized up to the half-radius of a 225 L bituminized drum, the matrix of which is very rich in hydrogen. Deeper characterization in concrete is possible but limited by counting statistics due to photon attenuation in this dense matrix and, unless large inspection volumes are considered, by the lack of spatial selectivity of the tagged neutron beam due to neutron scattering. [ABSTRACT FROM AUTHOR]

The effect of long-term mixed-waste contamination, particularly uranium and nitrate, on the microbial community in the terrestrial subsurface was investigated at the field scale at the Oak Ridge Integrated Field Research Challenge (ORIFRC) site in Oak Ridge, TN. The abundance, community composition, and distribution of groundwater microorganisms were examined across the site during two seasonal sampling events. At representative locations, subsurface sediment was also examined from two boreholes, one sampled from the most heavily contaminated area of the site and another from an area with low contamination. A suite of DNA- and RNA-based molecular tools were employed for community characterization, including quantitative PCR of rRNA and nitrite reductase genes, community composition fingerprinting analysis, and high-throughput pyrotag sequencing of rRNA genes. The results demonstrate that pH is a major driver of the subsurface microbial community structure and that denitrifying bacteria from the genus Rhodanobacter (class Gammaproteobacteria) dominate at low pH. The relative abundance of bacteria from this genus was positively correlated with lower-pH conditions, and these bacteria were abundant and active in the most highly contaminated areas. Other factors, such as the concentration of nitrogen species, oxygen level, and sampling season, did not appear to strongly influence the distribution of Rhodanobacter bacteria. The results indicate that these organisms are acid-tolerant denitrifiers, well suited to the acidic, nitrate-rich subsurface conditions, and pH is confirmed as a dominant driver of bacterial community structure in this contaminated subsurface environment. [ABSTRACT FROM AUTHOR]

Atomistic simulations were carried out to characterize the coordination environments of U incorporated in three Fe-(hydr)oxide minerals, goethite, magnetite, and hematite. The simulations provided information on U-O and U-Fe distances, coordination numbers, and lattice distortion for U incorporated in different sites (e.g., unoccupied versus occupied sites, octahedral versus tetrahedral) as a function of the oxidation state of U and charge compensation mechanisms (i.e., deprotonation, vacancy formation, or reduction of Fe(III) to Fe(II)). For goeshite, deprotonation of first shell hydroxyls enables substitution of U for Fe(III) with a minimal amount of lattice distortion, whereas substitution in unoccupied octahedral sites induced appreciable distortion to 7-fold coordination regardless of U oxidation states and charge compensation mechanisms. Importantly, U-Fe distances of ∼3.6A were associated with structural incorporation of U and cannot be considered diagnostic of simple adsorption to goethite surfaces. For magnetite, the octahedral site accommodates U(V) or U(VI) with little lattice distortion. U substituted for Fe(III) in hematite maintained octahedral coordination in most cases. In general, comparison of the simulations with available experimental data provides further evidence for the structural incorporation of U in iron (hydr)oxide minerals. [ABSTRACT FROM AUTHOR]

The subsurface migration of Pu may be enhanced by the presence of colloidal ferns of Pu. Therefore, complete evaluation of the risk posed by subsurface Pu contamination needs to include a detailed physical/chemical understanding of Pu colloid formation and interactions of Pu colloids with environmentally relevant solid phases. Transmission electron microscopy (TEM) was used to characterize Pu nanucolloids and interactions of Pu nanocolloids with goethite and quartz. We report that intrinsic Pu nanocolloids generated in the absence of goethite or quartz were 2-5 nm in diameter, and both electron diffraction analysis and HRTEM confirm the expected Fm3m space group with the fcc, PuO2 structure. Plutonium nanocolloids formed on goethite have undergone a lattice distortion relative to the ideal fluorite-type structure, fcc, PoO2, resulting in the formation of a bcc, Pu4O7 structure. This structural distortion results from an epitaxial growth of the plutonium colloid on goethite, leading to stronger binding of plutonium to goethite compared with other minerals such as quartz: where the distortion was not observed. This finding provides new insight for understanding how molecular-scale behavior at the mineral-water interface may facilitate transport of plutonium at the field scale. [ABSTRACT FROM AUTHOR]

The amount of plutonium discarded as wastes from the U.S. nuclear weapons complex appears to be significantly greater than the U.S. Department of Energy's 1996 declaration of its plutonium holdings. This is due to in part to improved radioactive waste characterization and the disposal of plutonium residues originally intended for use in weapons. The Hanford site in Washington State has the largest quantity of plutonium wastes, which pose potentially serious human risks to ground water and the near shore the Columbia River. The department should revise its accounting for plutonium, and take steps to remove plutonium discarded to the environment at Hanford, as it is required to do at Idaho National Laboratory. [ABSTRACT FROM AUTHOR]

Biogenic UO2 (uraninite) nanocrystals may be formed as a product of a microbial reduction process in uranium-enriched environments near the Earth's surface. We investigated the size, nanometer-scale structure, and aggregation state of UO2 formed by iron-reducing bacterium, Shewanella putrefacians CN32, from a uranium-rich solution. Characterization of biogenic UO2 precipitates by high-resolution transmission electron microscopy (HRTEM) revealed that the UO2 nanoparticles formed were highly aggregated by organic polymers. Nearly all of the nanocrystals were networked in more or less 100 nm diameter spherical aggregates that displayed some concentric UO2 accumulation with heterogeneríy. Interestingly, pure UO2 nanocrystals were piled on one another at several positions via UO2-UO2 interactions, which seem to be intimately related to a specific step in the process of growing large single crystals. In the process, calcium that was easily complexed with aqueous uranium(VI) appeared not to be combined with bioreduced uranium(IV), probably due to be lower binding energy. However, when phosphate was added to the system, calcium was found to be easily associated with uranium(IV), forming a new uranium phase, ningyoite. These results will extend the limited knowledge of microbial uraniferous mineralization and may provide new insights Into the fate of aqueous uranium complexes. [ABSTRACT FROM AUTHOR]

Abstract: The elemental characterization of materials constituting radioactive waste is of great importance for the management of storage and repository facilities. To complement the information brought by gamma or X-ray imaging, the performance of a fast neutron interrogation system based on the associated particle technique (APT) has been investigated by using MCNP simulations and by performing proof-of-principle experiments. APT provides a 3D localisation of the emission of fast neutron induced gamma rays, whose spectroscopic analysis allows to identify the elements present in specific volumes of interest in the waste package. Monte Carlo calculations show that it is possible to identify materials enclosed behind the thick outer envelop of a ≈1m3 cemented waste drum, provided the excited nuclei emit gamma rays with a sufficient energy to limit photon attenuation. Neutron attenuation and scattering are also predominant effects that reduce the sensitivity and spatial selectivity of APT, but it is still possible to localise items in the waste by neutron time-of-flight and gamma-ray spectroscopy. Experimental tests confirm that the elemental characterization is possible across thick mortar slabs. [Copyright &y& Elsevier]

A sample at high-level radioactive tank waste was characterized to provide a basis for developing a waste simulant. The simulant is required for pilot-scale testing of pretreatment processes in a nonradiological facility. The waste material examined was derived from the bismuth phosphate process, which was the first industrial process implemented to separate plutonium from irradiated nuclear fuel. The bismuth phosphate process sludge is a complex mixture rich in bismuth, iron, sodium, phosphorus, silicon, and uranium. The form of phosphorus in this particular tank waste material in of specific importance because that is the primary component (other than water-soluble sodium salts) that must be removed from the high-level waste solids by pretreatment. This work shows unequivocally that the phosphorus in this waste material is not present as bismuth phosphate. Rather, the phosphorus appears to be incorporated mostly into an amorphous iron(III) phosphate phase. The bismuth in the sludge solids is best described as BiFeO3. The behavior of phosphorus during caustic leaching of the bismuth phosphate process sludge solids is also discussed. [ABSTRACT FROM AUTHOR]

Abstract: The experimental and modeling results on the radionuclide concentrations in the Ignalina NPP operational waste are presented in the work. The scaling factors between easy-to-measure γ emitters 137Cs, 60Co and a number of difficult-to-measure radionuclides, the activity measurements of which are related to radiochemical procedures, α and β spectrometry, have been determined. The study shows that the scaling factor method can be applied for RBMK-1500 reactor waste characterization. The scaling factors were used in determination of the nuclide composition of operational radioactive waste and characterization of radioactive waste during the Ignalina NPP decommissioning. [Copyright &y& Elsevier]

Diurnal air samples were collected from the E-waste dismantling region Guiyu and the underwear industry region Chendian. This was the first report to present the diurnal variation of PBDEs in the atmosphere. The average concentrations of 11 PBDE congeners were 11,742pgm−3 in the daytime, and 4830pgm−3 at night in Guiyu, while the concentrations were lower in Chendian with 376pgm−3 in the daytime, and 237pgm−3 at night. BDE-209 accounted for 22% and 31.3% of the total PBDEs in Guiyu and Chendian, respectively. The diurnal variation trends of BDE-47, -99, -153, -183, and -209 were also analyzed in detail in the two regions. [Copyright &y& Elsevier]

Abstract: At PBMR, long-lived fission product release from spherical fuel spheres is calculated using the German legacy software product GETTER. GETTER is a good tool when performing calculations for fuel spheres under controlled operating conditions, including irradiation tests and post-irradiation heat-up experiments. It has proved itself as a versatile reactor analysis tool, but is rather cumbersome when used for accident and sensitivity analysis. Developments in depressurized loss of forced cooling (DLOFC) accident analysis using GETTER led to the creation of FIssion Product RElease under accident (X) conditions (FIPREX), and later FIPREX-GETTER. FIPREX-GETTER is designed as a wrapper around GETTER so that calculations can be carried out for large numbers of fuel spheres with design and operating parameters that can be stochastically varied. This allows full Monte Carlo sensitivity analyses to be performed for representative cores containing many fuel spheres. The development process and application of FIPREX-GETTER in reactor analysis at PBMR is explained and the requirements for future developments of the code are discussed. Results are presented for a sample PBMR core design under normal operating conditions as well as a suite of design-base accident events, illustrating the functionality of FIPREX-GETTER. Monte Carlo sensitivity analysis principles are explained and presented for each calculation type. The plan and current status of verification and validation (V&V) is described. This is an important and necessary process for all software and calculation model development at PBMR. [Copyright &y& Elsevier]

The fabrication and characterization of a microchamber electrode array for electrical and electrochemical studies of individual biological cells are presented. The geometry was tailored specifically for measurements from sensory hair cells isolated from the cochlea of the mammalian inner ear. Conventional microelectromechanical system (MEMS) fabrication techniques were combined with a heat-sealing technique and polydimethylsiloxane micromolding to achieve a multilayered microfluidic system that facilitates cell manipulation and selection. The system allowed for electrical stimulation of individual living cells and interrogation of excitable cell membrane dielectric properties as a function of space and time. A three-electrode impedimetric system was incorporated to provide the additional ability to record the time-dependent concentrations of specific biochemicals in microdomain volumes near identified regions of the cell membrane. The design and fabrication of a robust fluidic and electrical interface are also described. The interface provided the flexibility and simplicity of a "cartridge- based" approach in connecting to the MEMS devices. Cytometric measurement capabilities were characterized by using electric impedance spectroscopy (1 kHz-10 MHz) of isolated outer hair cells. Chemical sensing capability within the microchannel recording chamber was characterized by using cyclic voltammetry with varying concentrations of potassium ferricyanide (K3Fe(CN)6). Chronoamperometric recordings of electrically stimulated PC12 cells highlight the ability of the platform to resolve exocytosis events from individual cells. [ABSTRACT FROM AUTHOR]

Characterization is a first step to site cleanup or decommissioning of a disused nuclear facility. Good knowledge of the inventory of nuclides present, both type and location, is important in the design of an effective plan of remediation. Several systems based on HPGe detectors have been developed, both commercially and at laboratories, and are already in use for this purpose. Their use is somewhat complicated by the need for cryogenic cooling of the HPGe detector. Handling of liquid nitrogen in field situations is always difficult. Recent developments in low-power electromechanical cooling for HPGe detectors have made possible the construction of low weight, portable HPGe spectrometers with sufficient efficiency to perform the needed measurements in reasonable count times, without the need for liquid nitrogen. A mobile system was modified to use a battery-powered, Sterling-engine cooler on a nominal 40% relative efficiency detector. This system was characterized for efficiency and uniformity of response. The baseline spectra were analyzed using the DOE EML 1-meter methods to obtain representative MDA values for several nuclides of interest and typical counting times. [ABSTRACT FROM AUTHOR]

Boehmite nanofibers of high quality were synthesized through a wet-gel conversion process without the use of a surfactant. The long nanofibers of boehmite with clear-cut edges were obtained by steaming the wet-gel precipitate at 170°C for 2 days. Analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared emission spectroscopy (IES), as well as Raman spectroscopy were used to characterize the products. [ABSTRACT FROM AUTHOR]

Abstract: Within the food risk assessment procedure, the characterisation of the risk consists in the comparison of the dietary exposure with a health based guidance value established in a previous step. One of the identified weaknesses of this comparison is that the time is not considered in the description. The aim of this paper is to describe the dietary exposure as a dynamic process determined by the accumulation phenomenon due to successive dietary intakes and by the pharmacokinetics ruling the elimination process in between intakes. Such a process belong to the category of piecewise deterministic Markov processes, which are widely used in a large variety of applications in insurance risk or in operations research, ranging from queuing systems to inventory/storage models. The inputs of the Kinetic Dietary Exposure Model are the probability distributions governing intakes and inter-intake times, as well as the half-life of the contaminant in the human body. In this paper, an application to methyl mercury is considered, with exponential distributions for both the intakes and the inter-intake times, fitted from the French national consumption survey INCA, and a fixed half-life of 6 weeks for the elimination process. Within this framework, the process settles to a steady-state after approximately 5 years. A “Kinetic Tolerable Intake” (KTI), derived from the “Provisional Tolerable Weekly Intake” (PTWI) of 1.6μg/kgbw, is set to 14.6μg/kg and the probability of exceeding this threshold in the long run in the French adult female population is 1.22 E−15. [Copyright &y& Elsevier]

Abstract: The ability of Micromegas to detect neutrons over a wide energy range has already been demonstrated. However, in some nuclear experiments or applications, neutrons come with high photon flux disturbing the detectors. A new project for nuclear waste characterization using photonuclear reactions is under development at the CEA. One of the ideas is to detect the prompt neutrons produced by these kinds of reactions, which are accompanied by a strong flash. The micromegas detector has been chosen to detect these neutrons since it is quite insensitive to -rays under certain conditions. The configuration of this detector will be presented and its insensitivity demonstrated. Results from simulations and experiments will be shown. [Copyright &y& Elsevier]

Parchment from different sources has been analyzed by laser-induced breakdown spectroscopy (LIBS) for determination of Ca, Na, K, Mg, Fe, Cu, and Mn. The LIBS results were compared with results from inductively coupled plasma spectroscopy (ICP) and good correlation was obtained. Rapid distinction between modern and historical samples was achieved by discriminant analysis of the LIBS data. Animal type recognition was also possible on the basis of Mg/Cu emission peak ratio and Mg depth profiling. [ABSTRACT FROM AUTHOR]

The article reports on the physicochemical and mineralogical characterization of soil from a field research site in Oak Ridge, Tennessee. Site characterization is an essential step in determining the feasibility of remedial alternatives at hazardous waste sites. Physico-chemical and mineralogical characterization of uranium-contaminated soils in deeply weathered saprolite at Area 2 of the Department of Energy Field Research Center, was accomplished to examine the feasibility of bioremediation. The results indicate that concentrations of uranium in saprolite were closely related to low pH.

Abstract: The work presents the radioecological characterization of the new Brazilian uranium mining and milling site located in a semi-arid region of the country. The process characterization demonstrated that in heap leach plants most of the 226Ra remains in the leached ore. Despite the potential higher availability of radium isotopes in the soils of the studied region the lack of precipitation in that area reduces the leaching/mobilization of the radionuclides. High 226Ra and 228Ra concentrations were found in manioc while 210Pb was significant in pasture. It was suggested that a range from 10−3 to 10−1 may conveniently encompass most of the transfer factors (TF) values for soil/plant systems (i.e. involving different cultures, different soils and natural radionuclides). Impacts due to aerial transportation of aerosols and radon generated in the mining were proved to be minimal and restricted to an area not greater than 15km2. Finally, uranium complexation by carbonates was shown to be the main mechanism responding for the elevated radionuclide concentration in groundwater. [Copyright &y& Elsevier]

The formation of ammonia is inevitable during industrial-scale wet oxidation of wastewater if nitrogen-containing compounds are present. This undesired side-reaction requires additional measures for disposal. Common routes are either the use of noble metal-containing catalysts in the first oxidation step or end-of-pipe treatment. Problems rise for example from the insufficient stability of solid catalysts against hydrothermal impact. As most of the wet oxidation processes run at elevated pressure and temperature, running the heterogeneously catalysed oxidation of ammonia in the gas phase in a downstream reactor could protect the catalysts mainly from leaching and offers an economic alternative by avoiding loss of unused oxygen after depressurisation. This work reports on the oxidation of ammonia with air in steam atmosphere using Cu,Cr-containing supported and bulk catalysts at 235-305 °C and 30-60 bar. A copper chromite catalyst gave best performance (86% conversion at 305 °C, 45 bar, contact time 1 s). The spinel-type phase CuCr2O4 seems to be the active phase and shows superior stability. The results indicate that phase behaviour of water strongly influences activity and lifetime of catalysts. Characterisation of the solids (BET, XRD, XPS, ICP) proved that deactivation is mainly caused by leaching of Cr(VI) species from catalysts when the reaction runs near to dew point of water and by loss of BET surface area of supported catalysts due to hydrothermal impact. [ABSTRACT FROM AUTHOR]

Abstract: The French Alternative Energies and Atomic Energy Commission (CEA) and National Radioactive Waste Management Agency (ANDRA) are conducting an R&D program to improve the characterization of long-lived and medium activity (LL–MA) radioactive waste packages. In particular, the amount of toxic elements present in radioactive waste packages must be assessed before they can be accepted in repository facilities in order to avoid pollution of underground water reserves. To this aim, the Nuclear Measurement Laboratory of CEA-Cadarache has started to study the performances of Prompt Gamma Neutron Activation Analysis (PGNAA) for elements showing large capture cross sections such as mercury, cadmium, boron, and chromium. This paper reports a comparison between Monte Carlo calculations performed with the MCNPX computer code using the ENDF/B-VII.0 library and experimental gamma rays measured in the REGAIN PGNAA cell with small samples of nickel, lead, cadmium, arsenic, antimony, chromium, magnesium, zinc, boron, and lithium to verify the validity of a numerical model and gamma-ray production data. The measurement of a ∼20kg test sample of concrete containing toxic elements has also been performed, in collaboration with Forschungszentrum Jülich, to validate the model in view of future performance studies for dense and large LL–MA waste packages. [Copyright &y& Elsevier]

Abstract: The determination of radiolysis products is an important field both for the basic understanding of the radiolysis process and for process development. The latter case mainly dealing with processes for handling radioactive wastes. There are several kinds of radiolysis processes that originate from the different kinds of radiation. Gamma rays and high-energy beta has a high ability to penetrate barriers while alpha irradiation in principle has to be performed with the radiation emitting nuclide inside the actual sample. This can be a problem since most laboratories able to identify radiolysis products cannot handle alpha contaminated samples. In this paper we suggest the use of 211At as internal alpha emitting radionuclide. Due to its short half-life and decay to more or less stable daughters the radiolysis products may be examined using normal equipment without causing contamination. [Copyright &y& Elsevier]

• The aim of the study is to estimate the dihydrogen flow rate of 2714 radioactive waste drums. • Statistical techniques are used to define an optimal sampling strategy according to operational constraints. • A statistical analysis is performed on the measurement data to provide information on the quantity of interest with a good level of confidence. • The methodology allows to validate the representativeness of the selected measurement data set. • A predictive model is developed. This paper describes a methodology developed to define a sampling strategy adapted to operational constraints in order to characterize the dihydrogen flow rate produced by radiolysis reaction of organic materials contaminated with α-emitters in 2714 radioactive waste drums. The objective is to perform few but relevant measurements. Thus, a sample of only 38 drums has been measured and the statistical analysis of dihydrogen rate data has provided an estimation of the mean and upper bound consistent with global measurements of the ventilation system of the facility. In addition, a factorial data analysis has demonstrated the representativeness of the measurement data set and the validity of sampling strategy assumptions. Moreover, it has provided information used in a regression analysis to develop a linear prediction model of the dihydrogen flow rate production for radioactive waste drum characterization. [ABSTRACT FROM AUTHOR]

Automated sample processing techniques are desirable in radiochemical analysis for environmental radioactivity monitoring, nuclear emergency preparedness, nuclear waste characterization and management during operation and decommissioning of nuclear facilities, as well as medical isotope production, to achieve fast and cost-effective analysis. Dynamic flow based approaches including flow injection (FI), sequential injection (SI), multi-commuted flow injection (MCFI), multi-syringe flow injection (MSFI), multi-pumping flow system (MPFS), lab-on-valve (LOV) and lab-in-syringe (LIS) techniques have been developed and applied to meet the analytical criteria under different situations. Herein an overall review and discussion on these techniques and methodologies developed for radiochemical separation and measurement of various radionuclides is presented. Different designs of flow systems with combinations of radiochemical separation techniques, such as liquid–liquid extraction (LLE), liquid–liquid microextraction (LLME), solid phase extraction chromatography (SPEC), ion exchange chromatography (IEC), electrochemically modulated separations (EMS), capillary electrophoresis (CE), molecularly imprinted polymer (MIP) separation and online sensing and detection systems, are summarized and reviewed systematically. [ABSTRACT FROM AUTHOR]