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We carry out a comparative assessment of the degree of nuclear material disintegration and elimination in the samples of decellularized porcine dermis after using chemical, detergent and enzymatic decellularization methods. Decellularized dermis materials are promising materials as wound dressings. The chemical method (Protocol No. 1) was performed using NaOH and H2 O2 solutions; the detergent method (Protocol No. 2) involved the solutions of Triton X-100 and sodium deoxycholate in combination with Na2 -EDTA; the enzymatic method (Protocol No. 3) was based on the solutions of trypsin Versene and porcine pan creatic DNase. Subsequently, we analyzed the DNA amount in decellularized and native dermis (control group) samples. The results of this analysis showed positive results in all three protocols. It was found that the detergent method have advantages over other methods of producing decellularized dermis matrices.

The Rare-Earth Elements (REE) distribution pattern, along with the 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb isotopic ratios, can assist nuclear forensics practitioners and safeguards in tracing a uranium nuclear material back to its origin or in verifying the declared origin or accountancy. The present paper shows the first "in-house" analytical method, developed within the "Horia Hulubei" National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), with the purpose of monitoring REE and lead impurities in uranium oxide samples. A total of nine spiked replicate samples and three subsamples of UO2 Merck testing material were subject to the developed procedure. The method was validated in terms of selectivity, trueness (recovery), determination of the quantification limit, precision (repeatability) and ruggedness, proving that is suitable for monitoring REE and lead impurities in the tested matrix.

This paper describes the most common presently used methods for detecting uranium and plutonium isotopes after their introduction to environment. Known isotope ratios of U and Pu in different nuclear events are important tool for characterizing the sources of nuclear material. Detection techniques both in field and in laboratory are presented, as well as different models that can be used for identifying the origin and age of the nuclear material. Identification of the source of nuclear material in environmental samples is needed for estimating the quality and quantity of the nuclear hazard. This information is essential in risk assessment and crisis management, in chemical, biological, radiological and nuclear (CBRN) research after e.g. a terrorist attack, in radioecology and environmental radioactivity research.

Nuclear materials can be utilized not only for peaceful uses, but also for military purposes; hence, the international community has devoted itself to the control, management and safeguarding of nuclear materials. Nuclear materials are of varying degrees of usability for development of nuclear weapons. Thus, several methods for assessing the attractiveness of nuclear materials for nuclear weapons purposes have been proposed. When these methods are applied to unirradiated depleted, natural, and low-enriched uranium (DU, NU, and LEU), they are certainly classified as non-attractive nuclear materials. However, when nuclear material attractiveness is to be evaluated for potential radiological dispersal device (RDD) uses, it is required to develop a different method for the different aspects and factors. In the present study, we derived a novel method for evaluating nuclear material attractiveness for use in RDD development. To this end, the specific activity and dose coefficient were identified as the two sub-factors, and, in consideration of those, the mass causing detrimental health effects was determined to be the main factor impacting on nuclear materials attractiveness. Based on this factor, the attractiveness of unirradiated DU, NU, and LEU for RDD use was qualitatively compared with that of 137Cs.

The front-end of the nuclear fuel cycle encompasses several chemical and physical processes used to acquire and prepare uranium for use in a nuclear reactor. These same processes can also be used for weapons or nefarious purposes, necessitating the need for technical means to help detect, investigate, and prevent the nefarious use of nuclear material and nuclear fuel cycle technology. Over the past decade, a significant research effort has investigated uranium compounds associated with the front-end of the nuclear fuel cycle, including uranium ore concentrates (UOCs), UF4, UF6, and UO2F2. These efforts have furthered uranium chemistry with an aim to expand and improve the field of nuclear forensics. Focus has been given to the morphology of various uranium compounds, trace elemental and chemical impurities in process samples of uranium compounds, the degradation of uranium compounds, particularly under environmental conditions, and the development of improved or new techniques for analysis of uranium compounds. Overall, this research effort has identified relevant chemical and physical characteristics of uranium compounds that can be used to help discern the origin, process history, and postproduction history for a sample of uranium material. This effort has also identified analytical techniques that could be brought to bear for nuclear forensics purposes. Continued research into these uranium compounds should yield additional relevant chemical and physical characteristics and analytical approaches to further advance front-end nuclear fuel cycle forensics capabilities.

Uranium is the most common element in the nuclear fuel cycle. Different techniques have been used for analyzing the isotopic composition of uranium. Precise determination of uranium isotopic ratios for an efficient control of nuclear material was carried out through the modification of the used chromatographic method of uranium. Alpha spectrometry was utilized to identify different types of natural, depleted and enriched samples for safeguard purposes. Uranium element was extracted from other interfering radionuclides, purified, electrodeposited on a stainless-steel disc, and measured using alpha-spectrometer, then isotopic ratios were calculated. For comparison purposes, the samples were also measured using a hyper pure germanium (HPGe) spectrometer and the uranium isotopic ratios were obtained. The results obtained by both techniques were in agreement within difference ranged from -8.7 to 12%. It was concluded that alpha spectrometric measurements of uranium isotopes preceded by efficient radiochemical separation using extraction chromatography is a fast and reliable technique for safeguard purposes.

Cadmium zinc telluride (CZT) semiconductor detectors can be used as medium-resolution gamma-ray spectrometers, with the main advantage of a high portability and operation at room temperature. Their characteristics in terms of detection efficiency and resolution fall between the performance of sodium iodide and germanium detectors. One of the disadvantages of a CZT detector is the presence of a pronounced low-energy tail in the peak shape that complicates the analysis of spectra with overlapping peaks. The range of applications of CZT detectors includes verification measurements of fresh and irradiated nuclear material for safeguarding nuclear materials.

Highlights • Intensified reprocessing of silica-based microstructures and its biohybrid. • Parametric study of reprocessing of microstructures. • Kinetics of uranium recovery from substrates. • Morphology and recyclability study of the substrates after sonication and uranium recovery., Use of nanomaterials to remove uranium by adsorption from nuclear wastewater is widely applied, though not much work is focused on the recovery of uranium from the sorbents. The present work reports the recovery of adsorbed uranium from the microstructures of silica nanoparticles (SiO2M) and its functionalized biohybrid (fBHM), synthesized with Streptococcus lactis cells and SiO2M, intensified using ultrasound. Effects of temperature, concentration of leachant (nitric acid), sonic intensity, and operating frequency on the recovery as well as kinetics of recovery were thoroughly studied. A comparison with the silent operation demonstrated five and two fold increase due to the use of ultrasound under optimum conditions in the dissolution from SiO2M and fBHM respectively. Results of the subsequent adsorption studies using both the sorbents after sonochemical desorption have also been presented with an aim of checking the efficacy of reusing the adsorbent back in wastewater treatment. The SiO2M and fBHM adsorbed 69% and 67% of uranium respectively in the second cycle. The adsorption capacity of fBHM was found to reduce from 92% in the first cycle to 67% due to loss of adsorption sites in the acid treatment. Recovery and reuse of both the nuclear material and the sorbent (with some make up or activation) would ensure an effective nuclear remediation technique, catering to UN's Sustainable Development Goals.

In this paper, the physical inventory taking of nuclear materials (under safeguards agreement) at a nuclear fuel research laboratory has been considered. Nuclear materials with different forms and sizes were verified. The verification method was based on nondestructive measurements of gamma radiation emitted from nuclear material. Some of the parameters which affect NM mass estimation were calculated using Monte Carlo method. The proposed procedure covers different forms found at the nuclear fuel research laboratory including spherical, parallelepipeds and cylindrical shapes with different sizes. The present procedure could be very useful for safeguards purposes. Average accuracies for the estimated 235U masses of about − 0.159% and − 0.0935% with a precision of about 2.4% and 7.85% are obtained for MCNP and MGAU, respectively. This work aims to verify experimental measurements of nuclear materials’ samples with different shapes and sizes in a short time. These experimental measurements verifications can be quickly performed using the general-purpose Monte Carlo N-Particle code (MCNP).

Uranium ore concentrate (UOC) is an important nuclear material of interest for Canada. A large scale analytical program is being led by the Directorate of Security and Safeguards (DSS) of the Canadian Nuclear Safety Commission (CNSC) to establish a reference dataset of UOCs that have passed through and/or are currently under Canadian regulatory control. Isotopic ratios are among the signatures being captured under the reference dataset. Accelerator Mass Spectrometry (AMS) has been used for the measurement and assessment of 236U/238U and 187Os/188Os, respectively. Furthermore, since UOCs have uranium typically concentrated to ≥70% by weight, a direct-AMS assay method is possible wherein the samples can be measured without time consuming chemical digestion and processing. Using this direct-AMS approach, several related ratios (231Pa/238U, 230Th/238U, 226Ra/238U) were also assessed within the data acquisition sequence used for measuring the 236U/238U ratios, and 185Re, 187Re and 187Os, 188Os, 191Ir and 193Ir in the sequence for the 187Os/188Os ratios. The sum of these results can be shown together in a “bar-code” pattern to strengthen the capability for UOC source identification. Unexpectedly large 236U/238U ratios (up to ≥1 × 10−7) have been found in several UOC samples. The 187Os/188Os ratio has also been shown for the first time to be a viable supplementary signature of UOCs. This work shows that the direct-AMS method has the potential to become an effective tool for nuclear forensics provenance assessment applications with UOCs. The implications of the results, and the need for further refinement of the sputter target preparation, as well as the Cs+ sputter ion source itself, are also discussed.

Radiochronometric data, a key signature in evaluating the provenance and process history of nuclear material out of regulatory control, are conventionally acquired via multi-collector mass spectrometry. Here we explore the potential of age-dating by single-collector mass spectrometry. To evaluate model age accuracy/precision across different instrument designs, we performed 230Th–234U and 231Pa–235U radiochronometry of CRM 125-A using two single-collector and one multi-collector plasma source mass spectrometers. Single-collector instruments produce accurate model ages for this uranium standard and thus hold promise for nuclear forensics radiochronometry. Increased acquisition of age information via multiple instrument designs will bolster the global response to nuclear interdictions.

There is a shortage of reliable information on the highly enriched uranium (HEU) stockpile, production capabilities, and natural uranium reserves of the Democratic People's Republic of Korea (DPRK or North Korea). It is, however, possible to estimate DPRK’s nuclear material reserves using the data in the open literature and considering various scenarios. Based on our literature survey and analysis we are projecting DPRK’s natural uranium reserves and their production capabilities of weapons-grade HEU. We also report the uncertainties associated with DPRK’s uranium enrichment capabilities due to the differences in estimates provided in the literature. Our analysis shows that given the range of the estimates of DPRK’s natural uranium ore reserves, its nuclear weapons program is unlikely to be constrained by uranium resources, provided they have the required mining and milling capacities.

Here we report the results of multiple analytical techniques on sub-mm particulate material derived from Unit 1 of the Fukushima Daiichi Nuclear Power Plant to provide a better understanding of the events that occurred and the environmental legacy. Through combined x-ray fluorescence and absorption contrast micro-focused x-ray tomography, entrapped U particulate are observed to exist around the exterior circumference of the highly porous Si-based particle. Further synchrotron radiation analysis of a number of these entrapped particles shows them to exist as UO2—identical to reactor fuel, with confirmation of their nuclear origin shown via mass spectrometry analysis. While unlikely to represent an environmental or health hazard, such assertions would likely change should break-up of the Si-containing bulk particle occur. However, more important to the long-term decommissioning of the reactors at the FDNPP (and environmental clean-upon), is the knowledge that core integrity of reactor Unit 1 was compromised with nuclear material existing outside of the reactors primary containment., The larger particulates from reactor Unit 1 of the Fukushima Daiichi Nuclear Power Plant have received sparse attention compared to the Unit 2 particulate. Here the authors perform the higher-resolution and 3-dimentional analysis of several high-density micron-scale fragments, from within a larger Unit 1-derived representative ejecta particle.

Various procedures (precipitation, extraction, chromatography) have been tested for treatment of solutions from Davies-Gray analysis of nuclear material samples to remove uranium. The anion-exchange chromatography gave the best results, ensuring efficient removal of the majority of interfering impurities (Fe, Cr, V, Mo).

This study presents the development and the comparison of high accuracy methods for uranium isotope determination by thermal ionization mass spectrometry. Two methods for uranium minor isotope ratio determination were compared in term of accuracy, analysable quantity, analysis time and versatility: the total evaporation and the classical method with multi-dynamic sequences. The mathematical correction of the abundance sensitivity and the detector calibration within the classical method helps decreasing the uncertainties and the biases compared to the total evaporation method. This comparative study was conducted within the framework of the “2017 Nuclear Material Round Robin” participation organized by the International Atomic Energy Agency.

Since 1987, the CEA’s Committee for the establishment of analysis methods (CETAMA) has regularly implemented interlaboratory comparisons, entitled “evaluation of the quality results of analysis in the nuclear industry” (EQRAIN). Notably, the EQRAIN U and EQRAIN Pu interlaboratory comparisons assess proficiency in measuring a mass content of uranium or plutonium in reference solutions. This paper presents the results of measurement uncertainty assessments from EQRAIN U and EQRAIN Pu comparisons over 20 years of exercises (1997–2016). The mathematical approach developed in this work allowed to estimate the impact of short-term systematic and random errors to the overall uncertainty of each analytical method used in the interlaboratory comparison program. This statistical analysis shows a good consistency between measurement uncertainty values from EQRAINs and the measurement uncertainty target values established by the International Atomic Energy Agency for nuclear material balances (ITVs-2010).

The main objective of the IAEA verification activities is the timely detection of the switching of a significant quantity of nuclear material (NM). However, from the point of nuclear security the multiple switching of "small" quantities of nuclear material with the aim of their subsequent collection also constitutes one of the main threat to ensuring the exceptionally peaceful use of nuclear materials. In this article this threat assessments were performed under the scenario of diversification of uranium switching. It is shown that diversification of 4%-uranium switching can lead to a substantial increase (up to 30 times) of the risk of uranium disuse even with carrying out proper uranium control and protection. However this effect is observed only when there are large opportunities to search for insiders (the search area is comparable to the existing set of nuclear facilities). The obtained results also prove that a reduction in the level of NM safe management at facilities could allow the collector to complete a chain of unauthorized actions with a significant probability ( P S Q > 0.1 ).

Carry out independent measurements is requisite during nuclear safeguards inspection activities, at nuclear facilities and location outside facility (LOFs), to consider operators' declaration. 235U enrichment value estimation is a significant activity in nuclear material accounting and accountancy. The shortage of standard radioactive sources suitable to γ-ray detectors calibration for field measurements lets to use analysis methods for detectors calibration. Our work gives an overview of uranium enrichment estimation using two different analysis methods. A set of Standard Nuclear Material (SNM) samples, with cylindrical shapes and different enrichment percentage, was used to perform the experimental measurements. Count rate due to the most prominent γ-ray signatures for 235U and 238U isotopes was measured using germanium detector. The isotopic masses calculated based on the activity value estimated for 235U and 238U isotopes by ISOCS™ software efficiency calibration. Also, MGAU software was used to estimate the isotopic fractions of uranium. 235U enrichment value for each sample was calculated using the two analysis methods. The results obtained using different enrichment analysis methods were compared with each other and with the certified value for each sample.

International audience; Oxide dispersion-strengthened materials are reinforced by a (Y, Ti, O) nano-oxide dispersion and thus can be considered as nanostructured materials. In this alloy, most of the nanoprecipitates are (Y, Ti, O) nano-oxides exhibiting a Y2Ti2O7 pyrochlore-like structure. However, the lattice structure of the smallest oxides is difficult to determine, but it is likely to be close to the atomic structure of the host matrix. Designed to serve in extreme environments—i.e., a nuclear power plant—the challenge for ODS steels is to preserve the nano-oxide dispersion under irradiation in order to maintain the excellent creep properties of the alloy in the reactor. Under irradiation, the nano-oxides exhibit different behaviour as a function of the temperature. At low temperature, the nano-oxides tend to dissolve owing to the frequent ballistic ejection of the solute atoms. At medium temperature, the thermal diffusion balances the ballistic dissolution, and the nano-oxides display an apparent stability. At high temperature, the nano-oxides start to coarsen, resulting in an increase in their size and a decrease in their number density. If the small nano-oxides coarsen through a radiation-enhanced Ostwald ripening mechanism, some large oxides disappear to the benefit of the small ones through a radiation-induced inverse Ostwald ripening. In conclusion, it is suggested that, under irradiation, the nano-oxide dispersion prevails over dislocations, grain boundaries and free surfaces to remove the point defects created by irradiation.

On this paper it is presented the main physics features of the thorium as a nuclear material and a security analysis due to insertion of ThO2 in a PWR nuclear reactor fuel by the determination and assessment of the sensitivity coeficients through the Standardized Computer Analyses for Licensing Evaluation - SCALE 6.1 nuclear code system. This work was motivated by the world tendencies to reseach and development of nuclear fuels based on thorium, because the limitations of uranium resources and the importance of nuclear energy to the humanity.

Understanding the circumstances of the undeclared 2017 nuclear release of ruthenium that led to widespread detections of the radioisotope 106Ru in the Eurasian region, and whether it derives from a civilian or military source, is of major importance for society and future improvements in nuclear safety. Until now, the released nuclear material has merely been studied by analyzing short-lived radioisotopes. Here, we report precise measurements of the stable isotopic composition of ruthenium captured in air filters before, during, and after the nuclear release, and find that the ruthenium collected during the period of the 2017 nuclear release has a non-natural isotopic composition. By comparing our results with ruthenium isotopic compositions of spent nuclear fuels, we show that the release is consistent with the isotopic fingerprints of a civilian Russian water-water energetic reactor (VVER) fuel at the end of its lifetime, and is not related to the production of plutonium for nuclear weapons., A cloud of enhanced ruthenium concentrations has been observed over Europe in 2017, but no country has acknowledged responsibility for this nuclear release. Here, the authors show that the stable isotopic composition of ruthenium emitted from nuclear fuel reprocessing during the 2017 event is consistent with the isotopic signature of civilian Russian nuclear reactor fuel.

The proliferation resistance (PR) of an inert matrix fuel (IMF) in the transuranic nuclear fuel cycle (NFC) of a high temperature gas cooled reactor is evaluated relative to the uranium and plutonium mixed-oxide (MOX) NFC of a light water reactor using PRAETOR code and sixty-eight input attributes. The objective is to determine the impacts of chemical stability of IMF and fuel irradiation on the PR. Specific material properties of the IMF, such as lower plutonium content, carbide ceramics coating, and absence of 235U, contribute to enhance its relative PR compared to MOX fuel. The overall PR value of the fresh IMF (an unirradiated direct use material with a one-month diversion detection timeliness goal) is nearly equal to that of the spent MOX fuel (an irradiated direct use nuclear material with a three-month diversion detection timeliness goal). Final results suggest a reduced safeguards inspection frequency to manage the IMF.

Developing new state-of-the-art, low-cost and radiation hard detectors is an extremely difficult challenge which can be tackled only by a multisciplinary group of scientists and engineers from various fields having access to different infrastructure.

Albania has not a Research Reactor, Nuclear Power Plant, but use radioactive/nuclear materials and sources of the Ist–Vth category according their classification. Albanian institutions, Institute of Nuclear Physics (INP) and Radiation Protection Commission (RPC) have established a system of regulations and guidance to arrange the preparedness for response on-site area for practices with radioactive/nuclear that could necessitate intervention in emergency situation (Treatment of liquid R/W contains 226Ra, 90Sr, 238Pu, 137Cs isotopes at the Radiochemistry Department. INP, Technical Report, Tirana, 1998). The safety/security of risk assessment in facilities that utilize radioactive/nuclear material was performed considering its impact in environment, workers and public. A national legal framework was established providing among others objectives based in internationally agreed principles and national developments of policies/strategy for nanomaterials for environment safety/security by radioactive/nuclear agents at critical infrastructure facilities in Albania (Vaseashta A, Dimova-Malinovska D, Marshall J Nanostructure and advanced materials. Springer, Dordrech, 2005). Since 1998, a centralized storage facility exists for waste management and it was situated within IANP territory together with radiopharmaceutical Lab. Last decade substantial progress has been made in improving safety/security of radioactive/nuclear material worldwide, as well as in Albania. Al-Qa’ida and associated extremist groups have a wide variety of potential agents and delivery means to choose from for chemical, biological, radiological, or nuclear attacks. Terrorism groups continuously expressed interest in unleashing radiological terrorism by building and using radiological dispersal devices, known as “dirty bomb”. Materials, such as: commercial radioactive sources or enriched uranium/plutonium could fuel as crude nuclear material at such device. (Counter terrorism challenges regarding the process of critical infrastructure protection, 2011) Radioactive nuclear wastes generated from nuclear facilities or by radiological terrorism attack should be converted in stable forms, to be stored, disposed in safety/secure manner, in order to have as low as reasonably achievable (ALARA) environmental impact. Radiochemistry Division in institute has treated Low Level Liquid Waste generated by its Labs that contain 226Ra, 238Pu, 90Sr, 137Cs isotopes, using nanomaterial as absorber agents like: korthpule-kaolin, Al2O3x2SiO2x2H2O clay, and Tirana Factory Bricks clay, to adsorb above ions. We performed studies in Lab scale to decrease the activity/concentration of wastes, helping the precipitation of radioactive products on PO3−3, OH− ions form, adding sorption nanoagent such as: activated coal, metal powder mixed with different types of clay. Results shown, that montmorilonity Al2[(OH)2Si14O10]xnH2O is few effective as kaolin, which has ion-exchange capacity lower as the first clays used in our Lab, and its ion-exchange velocity was higher. The radioactivity of Low Level Liquid Waste was decreased in considerably using only clays, but this method request large amount of kaolin, increasing the precipitate volume. The experiments repeated using different sorption masses, temperatures, and time (min) of the clays, to absorb 226Ra, 238Pu, 90Sr and 137Cs. The results shown different absorption coefficients for decontamination of LLLW amounts reducing in considerable manner their volume (Chemical treatment of Radioactive /Waste, IAEA, technical report series No. 89, Vienna, 1968; Chemical precipitation processes for treatment of aqueous Radioactive /Waste, IAEA, technical report series No. 337, Vienna, 1992; Handling and treatment of radioactive aqueous Radioactive /Waste, IAEA, TEC/DOC–654, Vienna, 1992).

Safeguards verification of uranium and plutonium in high-radioactivity nuclear material is currently performed using destructive analysis techniques. However, the preparation method is a burden on both the safeguards inspectors and facility operators. While nondestructive assay (NDA) techniques would improve the efficiency and time, there are no passive NDA techniques available to directly verify the U and Pu content. As an alternative, the JAEA and JRC are collaboratively developing the Delayed Gamma-ray Spectroscopy (DGS) active-interrogation NDA technique to evaluate the fissile composition from the unique fission product yield distributions. To analyze the data we are developing an Inverse Monte Carlo (IMC) method that simulates the interrogation and evaluates the individual contributions from the mixed nuclear material to the composite spectrum. While the current nuclear data affects the ability to evaluate the composition, the IMC analysis method can be used to determine the systematic uncertainty contributions and has the potential to improve the nuclear data. We will present the current status of the DGS collaborative work as it relates to the development of the DGS IMC analysis.

As part of its R&xD activities in the fields of radioactivewaste drum storage and homeland security, the NuclearMeasurement Laboratory of CEA Cadarache has started studiesrelated to the detection of induced delayed fission gamma rays asa signature of U/Pu presence either in radioactive wastes or incargo containers and luggage. The study described in the presentpaper explores the feasibility of detecting fission delayed gammarays of nuclear materials interrogated by a pulsed neutrongenerator. For this purpose, Monte Carlo simulations have beenperformed with ACT, the MNCP6 Activation Control Card.Simulated results have been compared with experimental data tovalidate the numerical model. Samples of uranium andplutonium have been irradiated for 2 hours with a pulsed D-Tneutron generator delivering 14 MeV neutrons with an averageemission of 8.107n/s, which are thermalised in a graphite cellcalled REGAIN. At the end of irradiation, activated nuclearmaterials were placed in a low-background, high-resolutiongamma spectroscopy station in order to detect delayed gammarays emitted by fission products. Anomalies have been observedin the calculated time decay curve of fission delayed gamma rayswith MCNP6 ACT card, but the time behavior is correct for non-fission activated materials like aluminum or copper. On the otherhand, the number of counts recorded in the main simulatedgamma ray lines from activated nuclear material fission productsis consistent with the experimental results, thus validating thesimulation scheme in view of further studies on thecharacterization of radioactive waste drums or special nuclearmaterial detection in cargo containers.

The behavior of 16Cr3Al ODS steel (oxide dispersion strengthened steel), widely employed structural fusion material, under high-intensity laser radiation with intensity up to 1014 W/cm2 was investigated in air, helium and vacuum surrounding. Employed system was 65 fs laser at 804 nm, with applied pulse energy up to 5.25 mJ. Morphological effects were studied – cracking, crater parameters (depth, cross-section), LIPSS (laser-induced periodic surface structures) formation at the crater periphery, hydrodynamic effects, as well as chemical variations on the surface. Ablation thresholds were also determined for all three ambiences (for 100 applied pulses), and they were 0.30 J/cm2, 0.23 J/cm2 and 0.39 J/cm2 in air, helium and vacuum, respectively. Plasma occurred in all experiments and it was most prominent in vacuum due to strongest laser-material coupling.

This chapter faces the realization that the same atoms that can produce life-saving electricity can also be used to construct weapons of mass destruction. Some facilities, such as enrichment and reprocessing, in the nuclear fuel cycle can also serve dual uses when considering proliferation. The original atomic bombs were constructed of highly enriched uranium and high-grade plutonium, but their development led to thermonuclear devices with much larger yields. Thus far, nuclear war has been avoided by policies such as mutual assured destruction and international agreements such as the Non-Proliferation Treaty. The International Atomic Energy Agency (IAEA) is charged with performing worldwide nuclear material safeguards inspections. The legacy of the nuclear weapons arms race has left considerable weapons-grade materials that must be dealt with.

Presented here are three case studies that demonstrate the breadth of bulk actinide analytical chemistry at Los Alamos National Laboratory (LANL). This laboratory was established during the Manhattan Project and is still considered one of the premier analytical laboratories for special nuclear materials characterization around the globe. First, the analytical chemistry of 238Pu is presented, showcasing the unique challenges of this high activity isotope. Next, the analysis of 241AmO2 is discussed from the perspective of supporting nascent production at LANL. Finally, the analytical chemistry support of the production of plutonium non-destructive assay standards is discussed. These examples paint a picture of the analytical capabilities needed to meet the dynamic challenges of LANL’s nuclear programs.

International audience; This paper presents a new methodology used to study transmutation damage in boron carbide (B$_4$C). B$_4$C samples were set in a specially designed sample holder and irradiated in a neutron thermal flux in the ILL reactor. After describing the sample holder and the irradiation conditions, this paper discusses the results of the first post-irradiation examinations by secondary-ion mass spectrometry (SIMS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results obtained for a B$_4$C disc with natural boron composition prove the efficiency of the methodology.

Under normal operating conditions, a pyroprocessing facility removes highly radioactive and nonradioactive fission product waste from used nuclear reactor fuel to recycle the remaining uranium (U),...

The measured model age is an important signature to constrain the production history of an unknown nuclear material. The aim of this work was to validate a rapid, robust quantification scheme for bulk uranium materials, amenable to multiple detection platforms. This work describes a combination of stacked columns, vacuum assisted separations, automation and a suite of analysis techniques to determine the ages of uranium materials and CRMs of known production history. The methodology allows for the determination of 234U/230Th and 235U/231Pa atom ratios via a novel approach, starting with a three resin column separation to allow high throughput and rapid turnaround. The materials analysed have concordant ages with known production histories, leading to the potential for expanding this work to additional chronometers, and the approach offers nuclear forensic practitioners an additional, advantageous separation methodology in the analysis of bulk uranium materials.

The use of a limited set of signatures in nuclear forensics and nuclear safeguards may reduce the discriminating power for identifying unknown nuclear materials, or for verifying processing at existing facilities. Nuclear proliferomics is a proposed new field of study that advocates for the acquisition of large databases of nuclear material properties from a variety of analytical techniques. As demonstrated on a common uranium trioxide polymorph, α-UO3, in this paper, nuclear proliferomics increases the ability to improve confidence in identifying the processing history of nuclear materials. Specifically, α-UO3 was investigated from the calcination of unwashed uranyl peroxide at 350, 400, 450, 500, and 550 °C in air. Scanning electron microscopy (SEM) images were acquired of the surface morphology, and distinct qualitative differences are presented between unwashed and washed uranyl peroxide, as well as the calcination products from the unwashed uranyl peroxide at the investigated temperatures. Differential scanning calorimetry (DSC), UV–Vis spectrophotometry, powder X-ray diffraction (p-XRD), and thermogravimetric analysis-mass spectrometry (TGA-MS) were used to understand the source of these morphological differences as a function of calcination temperature. Additionally, the SEM images were manually segmented using Morphological Analysis for MAterials (MAMA) software to identify quantifiable differences in morphology for three different surface features present on the unwashed uranyl peroxide calcination products. No single quantifiable signature was sufficient to discern all calcination temperatures with a high degree of confidence; therefore, advanced statistical analysis was performed to allow the combination of a number of quantitative signatures, with their associated uncertainties, to allow for complete discernment by calcination history. Furthermore, machine learning was applied to the acquired SEM images to demonstrate automated discernment with at least 89% accuracy.

A portable handheld laser-induced breakdown spectroscopy (HH LIBS) instrument was evaluated as a rapid method to qualitatively analyze rare earth elements in a uranium oxide matrix. This research is motivated by the need for development of a method to perform rapid, at-line chemical analysis in a nuclear facility, particularly to provide a rapid first pass analysis to determine if additional actions or measurements are warranted. This will result in the minimization of handling and transport of radiological and nuclear material and subsequent exposure to their associated hazards. In this work, rare earth elements (Eu, Nd, and Yb) were quantitatively spiked into a uranium oxide powder and analyzed by the HH LIBS instrumentation. This method demonstrates the ability to rapidly identify elemental constituents in sub-percent levels in a uranium matrix. Preliminary limits of detection (LODs) were determined with values on the order of hundredths of a percent. Validity of this methodology was explored by employing a National Institute of Standards and Technology (NIST) standard reference materials (SRM) 610 and 612 (Trace Elements in Glass). It was determined that the HH LIBS method was able to clearly discern the rare earths elements of interest in the glass or uranium matrices.

Safeguards of nuclear materials depend on both destructive and nondestructive assay (DA and NDA, respectively). Ultra-high-resolution microcalorimeter gamma spectroscopy has the potential to substantially reduce the performance gap between NDA and DA methods in determination of plutonium isotopic composition. This paper details the setup of a cryostat and microwave readout system for microcalorimeter gamma spectroscopy, the functionality of which has been successfully demonstrated.

Nuclear material in reprocessing facilities is safeguarded by random sample verification with additional process monitoring applied to solution masses and volumes within the tanks to maintain conti...

A multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) coupled to a 213 nm ns-laser was used to measure uranium isotope ratios (234U/238U, 235U/238U, and 236U/238U) in six solid nuclear certified reference materials (CRMs). The powdered CRMs, containing depleted, natural and low enriched uranium (U), were pressed into pellets, for straightforward handling of the nuclear material. Being analysed without dissolution, the experimental U isotope ratios of the solid materials were in good agreement with the corresponding certified values. The measured U isotope ratios in the samples were corrected for mass bias using a pelletised CRM containing nominally 2% enriched 235U. Scanning electron microscopy investigations of an actual sample from which material was previously ablated revealed that only 5 ng of sample is consumed during a single measurement. As such laser ablation MC-ICP-MS can be regarded as quasi-non-destructive and therefore is an ideal technique for the rapid but still accurate and precise determination of the uranium isotopic composition in solid samples for nuclear safeguards and forensic purposes. The proposed analytical procedure essentially assists the characterisation of the illicit nuclear material for hazard and origin assessment. Moreover, as the sample is also an evidence, it can be analysed with further techniques.

For better nuclear material accountancy, we had developed a non-destructive assay system dedicated to uranium waste drums (JAWAS-N: JAEA Waste Assay System at Ningyo-toge). The system is based on a fast neutron direct interrogation (FNDI) method. To clarify the characteristics of the FNDI method and the performance of JAWAS-N, experimental and computational mock-up tests were carried out using various dry materials that contained known amounts of natural uranium. As a result, linearity between the die-away time (τ2) and the counts of fast neutrons attributed to 235U fission was confirmed. Moreover, the MCNP simulation was performed to discuss the radial and axial dependences of 235U fission probability, neutron detection efficiency, and sensitivity on uranium distributions in the drum. The simulation results agreed with the empirical results reported in a previous paper, providing valuable information on the practice of FNDI-based uranium determination. Furthermore, the nominal detection limits of...

At a PUREX reprocessing facility, HNO3 solution with dissolved spent fuel, such as fission products (FP) and nuclear materials, flows in pipes and stores in tanks. To detect and deter the theft of nuclear materials from the aqueous process, measuring the 10.8 MeV gamma rays emitted by the 14N(n,γ)15N reaction activated by spontaneous neutrons from, for example, 242Cm, 244Cm, 238Pu, 240Pu, and 242Pu in nitric acid solution with dissolved spent fuel might be useful for continuous monitoring of liquid flow from the viewpoint of safeguards. In general, because high-dose gamma rays emitted from FPs are dominant below 3 MeV, it is expected that the 10.8 MeV peak would not be affected by the FP peaks. As the first step, a measurement configuration was simulated by PHITS code based on 5.3 and 10.8 MeV gamma rays activated by neutrons from a 252Cf source. In this paper, optimization of the detector and measurement system are reported.

The rotation method is a novel method for detecting nuclear materials using a neutron source such as californium. In this method, while a neutron source is rotated rapidly nearby a measurement object, neutron measurement is carried out by synchronizing the rotation motion. If the object contains a nuclear material, as the rotation speed increases, the larger deformation of time distribution of neutron counts is observed, which in turn resulted to the detection of the nuclear material. In addition to its features of low cost and portability, this method is capable of detecting uranium that emits very few spontaneous fission neutrons. This study presents the fundamental principle of this method and its effectiveness for detecting nuclear materials through the experimental verifications.

By now, vast amounts of plutonium have been accumulated in spent nuclear fuel from different types of reactors (power, research, propulsion) as part of the Soviet (Russian) nuclear program. Issues concerned with the future of the accumulated plutonium (or plutonium being accumulated), including its long-term storage, disposal or use as fuel in a closed fuel cycle, require an exact knowledge of where, in what quantities and in what condition plutonium is stored at a particular time point. The existing nuclear material control and accounting system does not provide for the required information. This study deals with the further evolution of a specialized database on civil plutonium (SDBP) in Russia the work on which was started in 2013 and which would allow preparing input data for system analytical investigations to support the decision-making on the future use of civil plutonium in Russia. The prime objective of the study is to enable the selection of technological batches of extracted plutonium for the manufacturing of the BN-800, BREST and BN-1200 fast reactor core loads. The SDBP can be also used to address a broader range of problems involved in justification of the closed nuclear fuel cycle. Cooperation with such powerful software systems as the CYCLE code will make it possible to perform high-accuracy calculations from a single workplace and within a compressed timeframe. Computer mechanisms were developed for processing and conversion of data, as well as mechanisms for the interaction with computational software systems (CYCLE) to prepare input data for the calculation of scenarios for the nuclear power evolution in Russia and worldwide based on thermal and fast reactors, including the closed nuclear fuel cycle.

A direct and simultaneous analysis of the age and isotopic composition of nuclear material at the particle scale is described in this study. By comparison with other conventional techniques such as inductively-coupled plasma mass spectrometry or thermal-ionization mass spectrometry, secondary ion mass spectrometry enables one to determine the ages of individual particles in a mixture of nuclear materials. Having access to the purification date can give precious information on the history of a nuclear facility or nuclear material for safeguarding purposes. The high sensitivity of this technique combined with its imaging capabilities enables one to detect and to sort out all particles according to their isotopic composition in one analysis. The succession of two microbeam analyses on an individual particle allows the determination of the precise 235U abundance and the model age. The methodology was successfully applied to a mixture of uranium particles coming from certified reference material with a 235U ab...

In January 1966, 2 US military aircraft collided over the skies of Palomares (Almeria). One of them carried thermonuclear bombs, which released plutonium and other radioactive materials upon striking the ground. The most contaminated earth and plants were immediately removed. The Indalo Project was launched to study the effects of nuclear material on the inhabitants and environment of Palomares. A total of 1,077 inhabitants have been monitored since then, and the official version is that the ionising radiation has not been related to any type of disease. However, secrecy has surrounded much of the investigations, and no trustworthy epidemiological study has been conducted in the area. Approximately 500g of plutonium and americium remains in Palomares. Although the risk for the population appears to be low, this radioactive material should be removed as soon as possible.

The Cernavoda Tritium Removal Facility (CTRF) will be built at Cernavoda Nuclear Power Plant (NPP) for tritium removal and recovery from tritiated heavy water during the operation of CANDU reactors.A Cryogenic Distillation process in combination with a Liquid Phase Catalytic Exchange (LPCE) process is used for tritium removal/recovery from tritiated water.According with the regulation “Implementation of a Nuclear Material Accountancy and Control System by Operators of Nuclear Installations (2009/120/Euratom)” of the European Commission, the operators of nuclear facilities are obliged to provide to the European Commission, regularly detailed information about their installations and the nuclear material in their possession. Also, according with the regulations of the Commission for Control of the Nuclear Activities (CNCAN) from Romania, a nuclear facility is mandated to apply a control system for nuclear guarantees.Therefore, an important issue for CTRF, should be the tritium accountancy in the fac...

Spectroscopic chemometric based on-line monitoring of used nuclear fuel (UNF) reprocessing solutions and characterization of legacy nuclear waste (LNW) stored at Hanford is discussed in this manuscript. Utilizing on-line and near real-time monitoring, as opposed to traditional off-line monitoring, can significantly reduce the cost, risk and improve the efficiency of characterizing UNF and LNW processing streams. Specifically, this manuscript will highlight the benefits of spectroscopy-based monitoring approaches, which generally include the ability to collect data non-destructively. Furthermore, significant literature precedence supports the use of various real-time analysis methods, including chemometric analysis, that enable near-instantaneous conversion of spectroscopic data into information useable by process operators. This approach can accurately quantify and qualify nuclear material in near-real time enabling immediate condition characterization and potential diversion detection within UNF reprocessing streams and LNW. The ability to be applied in a real reprocessing plant and in an actual Hanford waste tank/transfer pipe has been demonstrated by applying this technique to accurately quantify analytes in real UNF streams and LNW samples. The future development of spectroscopy-based on-line monitoring is also discussed in this manuscript.

Radio-chronometry is an important signature in understanding the processing history of an unknown nuclear material. Knowledge of the formation of processing signatures is crucial to underpin nuclear forensic analysis. A precise concordant age from multiple chronometers gives confidence in the model age and can aid in determining processing history. Discordant chronometers can also help to refine specific processing histories where incomplete processing is known to occur. In this work we apply our rapid radiochemical methodology to materials of known provenance to further validate our capability. In these analyses we aim to study the effect of known processing history on model ages to build confidence in our understanding of the signature. We observe concordant chronometer pairs and agreement with processing history in samples where the model age assumptions are valid, such as purification by solvent extraction and specific processing techniques. This gives confidence in the utility of the analysis for forensic applications. Where discordance was observed in cast uranium metal samples, the signature was valuable for interpreting the processing history in terms of thorium and protactinium.

Materials play a key role in the safe and economical operation of nuclear reactors. Materials used in reactors also have to meet stringent chemical specifications for efficient performance. Commercial scale realization of nuclear materials has been a challenge to the nuclear industry. The history of development of nuclear materials has fascinating and unique examples of theoretical prowess as well as innovative experimentation and success in nuclear material development is characterized by synergy between the domains of laboratory research and industry. This paper describes the development of some of the important nuclear materials (uranium, plutonium, zirconium, boron, sodium and graphite), providing a historical perspective.

Automated introduction platforms integrated with inductively coupled plasma optical emission spectroscopy (ICP-OES) systems are continuously being improved. Expanding on the introduction systems, a newly developed automated ion chromatography system was explored for performing rapid in-line separations coupled to ICP-OES for the detection of trace elements in uranium. Trace elements are separated from a uranium material and the analytes are directed into the ICP-OES for subsequent detection. Detection parameters such as exposure time frequency, wavelength selection, and settling times were explored to gain insight on optimal detection schemes for in-line trace elemental analysis. The methodology was applied in the analysis of a uranium oxide (U3O8) certified reference material, CRM-124. It was found here that the sensitivity and uncertainty of the technique are greatly affected by how the ICP-OES is employed to collect data. Overall it was determined that faster exposure replicates can provide greater peak resolution with higher fidelity measurements but are limited with respect to the total analysis time (i.e., limited in detection timely separations). Zeta scores, which combine accuracy and uncertainty of certified values and experimental values, were used to validate the ICP-OES modes of operation.