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Atmospheric traces of radioactive xenon can be a strong indicator for underground nuclear fission reactions. 131mXe, 133Xe, 133mXe and 135Xe are the primary gaseous isotopes/isomers currently used to identify and classify nuclear events. During decay, each of these radioactive species produces a unique beta-gamma energy spectra, which can be measured using beta-gamma coincidence counting. Current operational Xe beta-gamma spectrum analysis software relies on Region of Interest (ROI) counting (Bowyer et al. in J Environ Radioact 59(2):139–151, 2002). This algorithm occasionally produces mismeasurements, especially when quantifying meta-stable isomers, due to overlapping ROIs and shifts in detector calibration in fielded systems over time (Ringbom and Axelsson in Appl Radiat Isot 156:108950, 2020). In an attempt to better de-convolve overlapping isotope spectra we have developed a technique that applies a supervised neural-network implemented in TensorFlow with Keras to classify and quantify the isotopes and mixtures of isomers based on their beta-gamma spectra—similar to image recognition. From this, we have improved upon the false-positive rate for classification and regression models, however challenges remain with dealing with differing detector energy calibrations and with estimating measurement uncertainty. [ABSTRACT FROM AUTHOR]

The correlation between the variations of multiplicity of prompt fission neutrons and the total kinetic energy of fission fragments was studied using a double ionization chamber in combination with a prompt fission neutron detector. An estimate was made of the systematic errors introduced by crosstalk caused by the multi-module structure of the neutron detector. [ABSTRACT FROM AUTHOR]

Although the principal physical behaviour of a material is inherently connected to its fundamental crystal structure, the behaviours observed in the real-world are often driven by the microstructure, which for many polycrystalline materials, equates to the size and shape of the constituent crystal grains. Here we highlight a cutting edge synthesis route to the controlled engineering of grain structures in thin films and the simplification of associated 3-dimensional problems to less complex 2D ones. This has been applied to the actinide ceramic, uranium dioxide, to replicate structures typical in nuclear fission fuel pellets, in order to investigate the oxidation and subsequent transformation of cubic UO2 to orthorhombic U3O8. This article shows how this synthesis approach could be utilised to investigate a range of phenomena, affected by grain morphology, and highlights some unusual results in the oxidation behaviour of UO2, regarding the phase transition to U3O8. [ABSTRACT FROM AUTHOR]

The nature of the spin distribution (SD) of fragments of low-energy induced and spontaneous double fission of nuclei is described theoretically. For two deformed fission prefragments, a mechanism for pumping large values of their relative orbital momenta and spins , due to the combined influence of bending and wriggling vibrations, is established, and analytical formulas for describing SP within the framework of such a mechanism are obtained for the first time. It is emphasized that for this mechanism the nucleus remains "cold" in the fission process, while in the statistical model it heats up to temperatures of MeV. A comparison of the calculated SDs for forced double fission of actinide nuclei and with the available experimental data showed reasonable agreement both in terms of the magnitude of the average spin values and in the sawtooth shape of the dependence of SP on the atomic number of fragments, which confirms the reliability of the pumping mechanism of large spin values of deformed fission fragments. For spontaneous double fission of the nucleus , possible reasons for the discrepancy between the theoretical SD and the experiment are indicated. [ABSTRACT FROM AUTHOR]

Objective: To investigate the safety and prognosis of enbloc or piecemeal removal after enbloc resection of a gastric GIST by comparing the clinical data of endoscopic en block resection and piecemeal removal (EP) and en block resection and complete removal (EC) of gastric GISTs. Methods: A total of 111 (43 endoscopic piecemeal, and 68 complete removal) patients with gastric GIST's ≥ 2 cm in diameter who underwent endoscopic therapy from January 2016 to June 2020 at the First Affiliated Hospital of Zhengzhou University were retrospectively analyzed. In all cases, it was ensured that the tumor was intact during the resection, however, it was divided into EP group and EC group based on whether the tumor was completely removed or was cut into pieces which were then removed. The patients' recurrence-free survival rate and recurrence-free survival (RFS) were recorded. Results: There was no statistically significant difference in RFS rates between the two groups (P = 0.197). The EP group had relatively high patient age, tumor diameter, risk classification, and operation time. However, there was no statistically significant difference in the number of nuclear fission images, postoperative hospitalization time, postoperative fasting time, complication rate and complication grading between the two groups (P > 0.05). Conclusion: Endoscopic piecemeal removal after en block resection of gastric GIST is safe and effective and achieves similar clinical outcomes as complete removal after en block resection. [ABSTRACT FROM AUTHOR]

This paper is an overview of the results obtained by a collaborative team of researchers from the Institute for Nuclear Research, Russian Academy of Sciences (INR RAS), and State Scientific Center of the Russian Federation—Institute of Physics and Power Engineering (SSC RF—IPPE) using the SVZ-100 lead slowing-down neutron spectrometer. The study focuses on measuring the fission cross sections of americium isotopes 241Am, 242mAm, and 243Am when bombarded by neutrons with energies below 100 keV. The high efficiency of the SVZ-100, facilitated by its substantial working-substance mass (100 t of high-purity lead) and neutron generation through proton irradiation with a 209-MeV accelerator at the INR RAS, enables the investigation of neutron-nuclear processes in microgram samples of radioactive nuclides, which is unattainable in experiments using time-of-flight spectrometry. Unique scientific information is acquired through lead slowing-down neutron spectrometry by collaborative research efforts at the INR RAS and SSC RF—IPPE. This information partially fills gaps or complements existing but often contradictory or insufficient data from experiments conducted on both time-of-flight installations and lead slowing-down neutron spectrometers at other research centers. The results of collaboration of the INR RAS and SSC RF—IPPE are documented in international nuclear data repositories, indicating, in several instances, the need for adjustments to recommended approximating and calculated values. Information is given on some implemented and planned studies on neutron fission cross sections of americium isotopes at other centers following completion of the collaboration of the INR RAS and SSC RF—IPPE. [ABSTRACT FROM AUTHOR]

This essay analyzes the historiography of the German attempts during the Second World War to develop and harness the economic and military applications of uranium fission as well as the postwar "politics of the past." This literature, which began immediately after the end of the war and continues to the present day, includes contributions from scientists, historians, journalists, playwrights, and other authors. The essay is divided into mostly chronological sections. [ABSTRACT FROM AUTHOR]

Uranium, regarded as an important element in nuclear fission energy schemes, is harmful to public health owing to its high toxicity and radioactivity. Herein, a novel fluorescent probe (SC4A@Tb3+) was developed using a one-step liquid-phase method with 4-sulfocalix[4]arene (SC4A) and rare earth–metal ions (Tb3+) as precursors to realize the accurate monitoring of uranyl ion (UO22+) detection. Based on the dynamic quenching mechanism, the SC4A@Tb3+ fluorescence quenching sensor for UO22+ detection was in the linear range of 0–0.36 µM, with a detection limit of 20 µg·L−1, and successfully quantified UO22+ in water and human serum samples. These results suggest that SC4A@Tb3+ is a potential sensing material for UO22+ detection. [ABSTRACT FROM AUTHOR]

In this paper, we consider the evolution of limited fission chains using the theory of branching processes for the development of a scientific and technical approach and methods of obtaining experimental data under laboratory conditions to verify models of neutron probabilistic processes in multiplying systems. [ABSTRACT FROM AUTHOR]

The article discusses the results of conceptual design and analysis for solid blanket of a hybrid fusion-fission facility based on a tokamak-type fusion reactor with magnetic plasma confinement. This blanket is intended to breed a nuclear fuel for the RF atomic industry by transmutation of the initial isotopes 238U and 232Th into the target 239Pu and 233U, respectively. Various design options of the solid blanket of the hybrid reactor facility (HRF) and its core, technological schemes of blanket mounting/dismounting and maintenance, choice of raw material compositions, coolants, and structural materials, and results of preliminary neutron analysis for the solid blanket are presented. [ABSTRACT FROM AUTHOR]

In experiments on polarized neutron beams, the effects indicating the rotation of a fissile nucleus have been observed. The main factor for this conclusion is the asymmetry of the coincidence count between the particle detectors accompanying the fission and the fragment detectors when reversing the direction of polarization of the neutron beam causing the fission of the studied nuclei. According to the opinions of the discovery authors, the measured asymmetry can be caused by the shift of the angular distribution in the direction or against the direction of the nucleus deformation rotation axis. In most publications, this shift is explained by the rotation of the angular distribution of particles in the direction of rotation of the nuclear fission axis. This article provides a simple and obvious explanation. [ABSTRACT FROM AUTHOR]

Fission reactions result in Nd isotope decay products which alter Nd isotopic compositions measured in nuclear debris. Trinitite samples measured by MC-ICP-MS show perturbations of Nd isotopes relative to 142Nd, the only isotope of Nd which is blocked from fission product decay. By measuring 144Nd/142Nd and the total number of atoms of 142Nd in the sample, it is possible to quantify the total number of fissions in nuclear debris, an important signature in post-detonation nuclear forensics. [ABSTRACT FROM AUTHOR]

Lead, lead–bismuth, and lead–lithium are candidate materials for liquid metal-based cooling media in the new generation of nuclear fission reactors and fusion systems. Despite the many benefits they offer, they also trigger a severe degradation of the structural steels in direct contact. One of the solutions to minimize the damage could be a deposition of thick, long-life protective coatings onto the steel surfaces. In our opening study, we have employed CS and RF-ICP technologies to deposit Mo and Fe coatings onto ferritic-martensitic type 9% Cr Eurofer-97 steel and its ODS variant, and tested them in the liquid PbLi environment at 600 °C for up to 1000 h. The results have shown that all coatings prevented the dissolution of the steels. On top of that, the Fe coatings also completely prevented the PbLi penetration, thereby providing a promising complex resistance to the corrosive medium. [ABSTRACT FROM AUTHOR]

Background: Silicon carbide-fibre/silicon carbide matrix (SiC/SiC) composites are candidate materials for accident tolerant fuel cladding in light water and advanced gas cooled nuclear fission reactors. The mechanical and damage behaviour of ceramic composites is sensitive to the composite geometry, the microstructure and the loading state. Reliable test methods are needed to investigate the subcritical damage that affects hermetic properties and strength, and this requires precise measurements under loading states that are representative of operating conditions. Objective: The objective was a novel methodology to measure the deformation of an internally pressurised ceramic composite tube. Methods: A burst test of an internally ground SiC/SiC (filament wound and braided) ceramic composite tube, pressurized by radial expansion of a compressed elastomer insert, was observed in situ by high resolution (synchrotron) X-ray tomography. The full field three-dimensional displacements were measured by digital volume correlation, with a precise rotation correction applied to obtain the relative radial and circumferential displacements of the tube wall for the first time. Results: The hoop strain, and its spatial variations, were determined as a function of the applied hoop stress and showed ovalisation and barreling of the tube. The quantity of subcritical matrix cracking increased with the tensile hoop strain, but the critical crack that caused rupture was not at the location of maximum tensile strain. Conclusion: Precise measurements of the deformation during the burst test found non-uniform hoop strains that caused a non-uniform distribution of subcritical cracking, which could influence the hermetic properties and strength. [ABSTRACT FROM AUTHOR]

Using a model of artificial radioactive particles, the effectiveness of the use of a saline laxative, Glauber's salt, as an antidote therapy agent was studied. Internal irradiation of laboratory animals (guinea pigs) and sheep was carried out under laboratory conditions with oral intake of particles simulating the radiation characteristics of young nuclear fission products, at doses that cause medium, severe, and extremely severe forms of radiation ulcerative gastroenterocolitis. During the first four days after radiation exposure, Glauber's salt was administered to each animal once a day either as 3 mL of 20% aqueous solution (for guinea pigs) or as a 0.5 L of 12% aqueous solution (for sheep). In all animals, the drug demonstrated a statistically significant antidote effect. Glauber's salt decreased the severity of radiation-induced ulcerative damage to the gastrointestinal tract, enhanced the speed of healing of radiation ulcers, and increased the survival of animals. The approach applied can be used in the search for new antiradiation antidotes. [ABSTRACT FROM AUTHOR]

The variances of the fission fragment mass distributions for the symmetric case, over a wide range of the fissility of the compound nucleus have been investigated within the framework of random neck rupture model (RNRM) proposed by Brosa et al. The shape of the fissioning nucleus is generated excluding c rel (i.e. c rel = 1 ) in the RNRM model, which results in more continuous shape of fissioning nucleus at boundaries connecting heads to neck in the scission shape. This shape-modified RNRM model has been used to analyse experimental data of mass variances for symmetric mass distributions of 27 systems in a wide region of fissility (0.7–0.95). The average total kinetic energies, ⟨ TKE ⟩ s, for these fissioning systems have been taken from Viola systematics. The neck radius is an important parameter of the RNRM model and this has been varied to fit the experimental mass variances data. The systematics of the resulting neck radii are studied as a function of fissility and nuclear potential through γ 0 , the surface energy coefficient. It is found that the neck radii that fit the experimentally observed variances of the mass distributions fall into two groups. Empirical formulae have been obtained for the neck radii for these two groups of fissioning systems. Usage of the empirical formulae for neck radii predict the mass variances reasonably well for five test systems and it is shown that these predictions of the neck radii are better than the predictions with the Rayleigh criterion. [ABSTRACT FROM AUTHOR]

The famous German author and playwright Bertolt Brecht lived in exile in Denmark from 1933 to 1939. During the last years of his stay, he was directly and indirectly involved with physicists at Niels Bohr's Institute for Theoretical Physics in Copenhagen. In the spring of 1938, he had a meeting with Christian Møller concerning his plan to write what became The Life of Galileo. Later, in the early months of 1939, Brecht became aware of and interested in the discovery of uranium fission, in part spurred by a radio broadcast with Møller and other physicists. The paper reconstructs what happened in Copenhagen and discusses how the events influenced Brecht's writing of Galileo and his views on science and society. It also reconsiders how he was to some extent inspired by Albert Einstein and made theatrical use of the ideas of the great physicist. [ABSTRACT FROM AUTHOR]

Molten chloride salt fast reactors (MCFRs) will require UCl3 dissolved in molten salt mixtures as fuel for nuclear fission. For infusing the salt with UCl3, bubbling HCl into NaCl-CaCl2 in contact with U metal was investigated. The reaction was run up to 9 h and yielded U concentration up to 0.652 wt.%. Open circuit potential between a W electrode and Ag/AgCl reference electrode yielded a potential consistent with uranium existing as U(III) in the salt. This demonstrates that HCl can be a very effective chlorinating agent to infuse MCFR fuel with UCl3 starting from U metal. [ABSTRACT FROM AUTHOR]

New precise measurements of angular neutron–neutron () correlations in the spontaneous fission of Cf were performed with the aim of studying the mechanism of prompt neutron emission in the nuclear fission process. In contrast to earlier studies, particular attention is given in the present experiment to exploring experimental systematic effects that owe their existence to neutron rescattering on the structural elements of the setup used and which distort angular distributions. The experimentally determined angular dependence of the number of coincidences for seven neutron-detection thresholds in the range between 490 and 2080 keV is compared with the results of refined model calculations in which the anisotropy of neutron emission in the fragment center-of-mass frame is taken into account. It is shown that these experimental data can be described successfully if, in addition to the bulk of neutrons from fully accelerated fission fragments, 6 to 10 of neutrons emitted isotropically in the laboratory frame are included in the total number of prompt fission neutrons. The energy distribution of this component is also determined. These extra neutrons may be interpreted as neutrons emitted at the instant of disintegration of the nucleus being considered (so-called scission neutrons). [ABSTRACT FROM AUTHOR]

Numerous measurements of fission product yields were performed since the discovery of the nuclear fission process. However, more precise and reliable fission product yields are requested. Lack of covariance matrices make difficult to use it for specific application purposes such as the propagation uncertainty of decay heat. In this work, we propose to measure independently the fission product mass yields for the whole heavy peak (including the symmetric mass region) for the 233 U (n th , f) reaction. Both average values and experimental covariance is provided. The fission product mass yields are measured with the LOHENGRIN recoil mass spectrometer of the ILL using an ionization chamber located at the focal plane. A new procedure of data taking has been developed in order to minimize the biases. Concretely several ionic charges and kinetic energy distributions have been measured for each mass. Particular attention has been considered in the monitoring of the target time evolution. Additional corrections were necessary in the symmetry mass region due to contaminants coming from the LOHENGRIN recoil mass spectrometer. A complex Monte Carlo analysis has been developed in order to better propagate all the uncertainties. The fission product mass yields of the 233 U (n th , f) and its associated covariance matrix has been produced. An overall good agreement has been observed with ENDF/B-VIII.0 in contrast with the JEFF-3.3 evaluation. A precision around 2% for the heavy peak has been measured. The experimental covariance matrix was also computed. In the symmetry mass region, two components were observed in the kinetic energy distribution. One of this component was considered as an artifact and was ruled-out. [ABSTRACT FROM AUTHOR]

The nuclear physical properties of austenitic chromium-nickel steel EK-164 (Fe–16Cr–19Ni–2Mo–2Mn–Nb–Ti–B) and its manganese-based modifications EK-164Mn (Fe–16Cr–20Mn–2Mo–Nb–Ti–B) and EK-164MnW (Fe–16Cr–20Mn–2W–Nb–Ti–B) under irradiation (up to 5 effective years) in the neutron spectra of fast power (BN-600) and thermonuclear (DEMO-C) reactors and after irradiation (nuclear cooling up to 1000 years) were determined. The investigations were based on using the ACDAM-2.0 calculation complex with consideration of the elemental (alloying and impurity) compositions of steels and typical neutron spectra of fission (BN-600) and fusion (DEMO-C) reactors. The entire set of nuclear physical characteristics of steels (primary radiation damage; transmutation of elements; radiogenic accumulation of elements, including hydrogen, helium, and boron; γ-dose rate; radioactivity; nuclear energy release; isotope contributions) is obtained and their comparative analysis is performed. The time intervals for fulfilling the criteria of low activation of steels after irradiation (γ-dose rate less than 10 mSv/h, radioactivity less than 1010 Bq/kg, energy release less than 10 W/m3) were determined. [ABSTRACT FROM AUTHOR]

A simple method for the production of 99Mo is proposed involving the fission of 235U loaded onto commercially available activated carbon fibers. The maximum uranium loading that could be achieved on the material was 0.35 mg g−1. The dependence of the metal ion loading on pH showed that in the pH range 6–9, Mo was not significantly bound to the carbon surface, whereas all other metal species investigated were relatively strongly held. This finding suggests that it should be possible to devise a process based on this new target material providing five-day irradiation in a high neutron flux does not alter the surface properties of the carbon matrix. [ABSTRACT FROM AUTHOR]

It is well known that prompt neutrons from nuclear fissions show anisotropic emission properties that have been studied for nuclear safeguards purposes. However, for further practical applications, thorough investigation of those properties from diverse perspectives needs to be done. In the present work, the energy dependency of prompt neutron anisotropic emissions by 244Cm and 240Pu was investigated using Monte Carlo simulations. In the results, the asymmetry of prompt neutron angular distributions showed a dependency on neutron energy thresholds, and its characteristic tendency was confirmed for both nuclides. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of the effect of irradiation with Kr15+ and Xe23+ heavy ions with energies of 147 and 220 MeV, respectively, on the change in the optical, structural and strength properties of ceramics ZrO2. Polycrystalline ZrO2 ceramics with a tetragonal type of crystal structure, which are highly resistant to external influences, mechanical strength to cracking, and hardness were chosen as the object of research. The choice of heavy ions Kr15+ and Xe23+ is due to the possibility of simulating the effect of nuclear fission fragments in an atomic reactor, and the choice of irradiation doses of 1 × 1013–1 × 1014 ion/cm2 is due to the possibility of simulating the effects of overlapping defect regions arising along the trajectory of ions in the material. Using the X-ray diffraction method, it was found that in the case of irradiation with heavy ions, an increase in the radiation dose leads to phase transformations of the tetragonal type of the crystal lattice into a cubic one. In this case, for the samples irradiated with Xe23+ ions at an irradiation dose of 1 × 1014 ion/cm2, an almost complete phase transformation is observed. Dependences of changes in strength and optical characteristics on the type of irradiation and dose load have been established. [ABSTRACT FROM AUTHOR]

A new process was developed to recover high specific activity (no carrier added) 99Mo from electron-accelerator irradiated U3O8 or uranyl sulfate targets. The process leverages a novel solvent extraction scheme to recover Mo using di(2-ethylhexyl) phosphoric acid following uranium and transuranics removal with tri-n-butyl phosphate. An anion-exchange concentration column step provides a final purification, generating pure 99Mo intended for making 99Mo/99mTc generators. The process was demonstrated with irradiated uranium targets resulting in more than 95% 99Mo recovery and without presence of fission products or actinides in the product. [ABSTRACT FROM AUTHOR]

The aim of this work is to study the radiation damage processes, as well as their subsequent evolution and the effect on the structural, optical and mechanical properties of BeO ceramics. The choice of the type of Kr15+ ions with an energy of 140 meV makes it possible to simulate the kinetics of radiation damage comparable to the effect of uranium fission fragments in a nuclear reaction. Dose loads, which ranged from 1011 to 1015 ion/cm2, make it possible to simulate both single effects of radiation damage in the case of irradiation doses of 1011–1012 ion/cm2, and the effects of overlapping radiation damage and their mutual influence on changes in the properties of ceramics. During the studies carried out, the kinetics of changes in ceramics properties from the radiation dose was established, and the critical doses at which ceramics properties deteriorate sharply were determined. Studies showed that a growth in the radiation dose, leading to an increase in the defective areas overlap probability, leads to grain crushing and an increase in dislocation density, which in turn, leads to a slowdown in degradation processes of the ceramics strength and hardness. [ABSTRACT FROM AUTHOR]

Alternative sources of neutron production other than nuclear fission reactions are important priorities in medical and nuclear applications due to costs, safety and ease of operation. In this work, 12 C and 13 C thick targets for neutron production through 12 C(d,n) 13 N and 13 C(d,n) 14 N , respectively, have been manufactured and characterized by different techniques. In order to evaluate the irradiation effects on these materials, the targets were irradiated with 150 keV proton beam. A complete characterization of these samples was performed using scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, Auger electron spectroscopy, X-ray photoemission spectroscopy and Raman spectroscopy. The results of these studies allowed us to establish that even though the irradiated samples present microstructural and chemical structure changes on its surface, the 12 C and 13 C thick targets were stable and would maintain their performance after proton irradiation at a fluence of 2.0 × 10 18 ions/cm 2 and 3.7 × 10 18 ions/cm 2 , respectively. [ABSTRACT FROM AUTHOR]

Atmospheric traces of radioactive xenon, in particular 131 m Xe , 133 Xe , 133 m Xe and 135 Xe , can provide "smoking gun" evidence to classify underground nuclear fission reactions. Current software used to quantify isomer concentrations relies on a Region of Interest (ROI) method to sort beta-gamma coincidence counts. This experiences errors when classifying nuclides, especially with metastable nuclides, due to the difficulty of deconvoluting overlapping ROIs and accounting for shifts in detector calibration over time. To address this uncertainty, our technique mathematically models the distinctive peaks in an isomer's beta-gamma spectrum. The function representations are then fitted to measured spectra to determine the concentrations of the primary isomers in the sample. From this proof-of-concept, we hope to create a more precise and accurate system to detect nuclear fission reactions. [ABSTRACT FROM AUTHOR]

Isospin symmetry has gained importance in nuclear phenomena involving heavy nuclei in recent years. We present empirical evidence of isospin dependence in the compound nuclear fission cross-sections and fission widths, which suggests the idea that the compound nucleus (CN) possibly retains the memory of the isospin when it is formed and affects the CN fission. This idea was first proposed by E.L. Yadrovsky [E.L. Yadrovsky, Phys. Lett. 55B, 157 (1975)]. An observable difference between the fission branching ratios in two different isospin states suggests that the CN seems to remember its isospin at the point of formation. Further, the data also suggest a possible new signature of weakening of the CN process and gradual transition to non-compound processes as the energy rises. This is a very interesting and useful observation which needs to be confirmed by further and more precise experiments. [ABSTRACT FROM AUTHOR]

Background: Primary hepatic leiomyosarcoma (PHL) is an extremely rare type of tumor. We herein report a case of a large surgically resected leiomyosarcoma of the liver. Case presentation: A 69-year-old man with a feeling of epigastric compression was referred for examination of an abdominal mass. He had no history of liver disease or alcohol abuse. Liver function tests indicated Child-Pugh class A. Tumor markers were negative. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a relatively well-contrasted 12 × 11 × 8 cm tumor with well-defined boundary replacing the lateral segment of the liver alongside multiple intrahepatic metastases. Several nodules up to 12 mm were found in both lungs, suggestive of metastasis. SUVmax of the liver mass and lung tumor in positron emission tomography were 10.4 and 1.5, respectively. Hepatocellular carcinoma was primarily suspected. Lateral segmentectomy of the liver was performed to confirm diagnosis and prevent tumor rupture. Macroscopically, the lateral segment of the liver had been replaced by a lobular or multinodular tumor with a maximum diameter of 15 cm. In pathological findings, the tumor consisted of bundle-like proliferation of complicated banding spindle-like cells with clear cytoplasm, accompanied by storiform pattern and compressed blood vessels. Nuclear fission images were observed in 8/10 HPF. Partial necrosis was present, with associated venous invasion and intrahepatic metastasis. Immunohistochemical staining for tumor cells revealed desmin, α-smooth muscle actin (αSMA), and h-caldesmon were all positive, informing a final diagnosis of PHL. The postoperative course was uneventful, and he was discharged on the 12th postoperative day. Conclusions: PHL is a rare malignant disease with relatively poor prognosis. To confirm a diagnosis of PHL, immunohistochemical analysis as well as histopathological findings is important. The preferred treatment is surgical resection, sometimes in combination with adjuvant chemotherapy and radiotherapy. Further studies are needed to elucidate and better understand this uncommon clinical entity. [ABSTRACT FROM AUTHOR]

Treatment and recycling of radioactive waste are major challenges for the nuclear energy sector. Pertechnetate anions, 99TcO4−, occur in nuclear waste and are formed mainly during nuclear fission. 99TcO4− is a very hazardous contaminant due to its long half-life and high solubility and mobility in water. The effective capture of 99Tc contamination at legacy nuclear sites remains a serious and unsolved environmental issue. In this work, 99TcO4−/ReO4− was adsorbed by compressible graphene–chitosan sponges with grafted tertiary amine groups. Moreover, the hydrophobic branched chains strongly reduced the interference of competitive anions during adsorption. Results show that 99TcO4−/ReO4− can be effectively removed even under highly acidic conditions and in the presence of competing anions. More than 98% of 99TcO4−/ReO4− was removed using simulated nuclear wastes. [ABSTRACT FROM AUTHOR]

This study introduces a derivative of the well-known optimization algorithm, Big Bang–Big Crunch (BB–BC), named Nuclear Fission–Nuclear Fusion-based BB–BC, simply referred to as N2F. Broadly preferred in the engineering optimization community, BB–BC provides accurate solutions with reasonably fast convergence rates for many engineering problems. Regardless, the algorithm often suffers from stagnation issues. More specifically, for some problems, BB–BC either converges prematurely or exploits the promising regions inefficiently, both of which prevent obtaining the optimal solution. To overcome such problems, N2F algorithm is proposed, inspired by two major phenomena of nuclear physics: fission and fusion reactions. In N2F, two concepts named "Nuclear Fission" and "Nuclear Fusion" are introduced, replacing the "Big Bang" and "Big Crunch" phases of BB–BC, respectively. With the "Nuclear Fission" phase represented through a parameter named amplification factor, premature convergence issues are eliminated to a great extent. Meanwhile, convergence rate and exploitation capability of the algorithm are enhanced largely through a precision control parameter named magnification factor, in the "Nuclear Fusion" phase. The performance of N2F algorithm is investigated through unconstrained test functions and compared with the conventional BB–BC and other metaheuristics including genetic algorithm, Particle Swarm Optimization (PSO), Artificial Bee Colony Optimization (ABC), Drone Squadron Optimization (DSO) and Salp Swarm Algorithm (SSA). Then, further analyses are performed with constrained design benchmarks, validating the applicability of N2F to engineering problems. With superior statistical performance compared to BB–BC, GA, PSO, ABC, DSO and SSA in unconstrained problems and improved results with respect to the literature studies, N2F is proven to be an efficient and robust optimization algorithm. [ABSTRACT FROM AUTHOR]

We have made observations of noble metal phase fission-product agglomerates and gaseous xenon within the fuel-cladding interaction (FCI) zone of a high-burnup UO2 fuel. The FCI is the boundary between the UO2 pellet outer surface and the inner wall of the oxidized Zr-liner/cladding of the fuel rod. These fission-product agglomerates are well known to occur within the spent fuel matrix, and although radionuclides have been reported by others, we reveal aspects of their speciation and morphology. That they occur as discrete particles in the oxidized Zr liner, suggests the occurrence of hitherto unknown processes in the FCI zone during reactor operation, and this may have implications for the long-term storage and disposal of these types of materials. As expected, the particle agglomerates, which ranged in size from the nanometer scale to the micrometer scale, contained mainly Mo, Ru, Tc, Rh, and Pd; however, we also found significant quantities of Te associated with Pd. Indeed, we found nanometer scale separation of the distinct Pd/Te phase from the other fission products within the particles. Often associated with the particles was concentrations of uranium, sometimes appearing as a "cloud" with a tail emanating from the fuel into the oxidized cladding liner. Many of the noble metal phase particles appeared as fractured clusters separated by Xe-gas-filled voids. Possible mechanisms of formation or transport in the cladding liner are presented. [ABSTRACT FROM AUTHOR]

The fission of the 181Re∗ nucleus formed via the 12C +169Tm reaction is studied at ELab= 77–89 MeV within the dynamical cluster model (DCM) for the choices of spherical as well as deformed fragments originated in binary decay channels of the of collective clusterization approach. The mass distribution of the compound nucleus 181Re∗ is analyzed for both choices and compared with the available data, and consequently the probable fission fragments are identified. The barrier height, barrier modification, and barrier penetrability of the fission fragments are investigated. The total fission cross-sections are calculated for spherical as well as deformed choices of fragmentation, and they are in nice agreement with experimental data. In addition, the fission emission times and the decay widths of the fission fragments are predicted for comparison with future experiments. Finally, the preformation behavior of spontaneous and induced fission paths are compared to give a better insight of the decay mechanism of 181Re nucleus. [ABSTRACT FROM AUTHOR]

Centrosomes represent the major microtubule organizing center (MTOC) in eukaryotic cells and are responsible for nucleation of the spindle, the vehicle of chromosome segregation. In human female meiosis, however, spindle assembly occurs in the absence of centrosomes or other MTOCs and microtubules are nucleated around chromosomes. In yeast, spindle formation in mitosis and meiosis depends on the activity of spindle pole bodies (SPBs), the functional equivalents of centrosomes; thus, SPBs and centrosomes use similar machineries to assemble spindles. Here, we develop a system to explore the molecular mechanisms supporting acentrosomal spindle formation using fission yeast meiosis as a model scenario. We achieve this situation by removing access of the SPBs to the nucleus after their duplication. Under these conditions, we observe self-assembly-based spindle formation in the nuclear environment, conferring an ability to segregate chromosomes independently of the SPBs. Our results open the possibility to utilize the experimental advantages of fission yeast for insights into the molecular basis of acentrosomal spindle formation in meiosis. [ABSTRACT FROM AUTHOR]

In employing the concept of the isotropy of space, the coefficients D of P-even, T-odd asymmetry in the angular distributions of prescission alpha particles emitted as third particles in the ternary fission of nonoriented target nuclei that is induced by polarized cold neutrons are expressed in the lowest orders of perturbation theory in the neutron polarization vector in terms of two P-even scalar coefficients D3 and D5 associated with, respectively, triple and quintuple correlations depending on the unit vectors kα, kLF, and σn, which determine the features of the coefficients being studied. On the basis of the above representation, the experimental values of the coefficients D3 and D5 are determined by using the experimental values of D and the angular distributions of alpha particles emitted in the analogous reaction induced by unpolarized neutrons. The resulting coefficients D3 and D5 are compared with the analogous coefficients found by means of the classical method of trajectory calculations and by means of quantum-mechanical fission theory relying on the concept that it is the rotational mechanism that is responsible for the appearance of the asymmetries being studied. It turns out that the classical method, which disregards the interference between fission amplitudes for different S-wave neutron resonances, leads to an irremovable contradiction between the calculated coefficient D3 and the analogous experimental coefficient for the 233U target nucleus. In the case of employing the quantum-mechanical approach, it is concluded that three-body calculations of the Coriolis interaction—perturbed amplitude of the angular distributions of alpha particles moving in the Coulomb fields of fission fragments are required for the 233U target nucleus. [ABSTRACT FROM AUTHOR]

The BONUS model of the formation, radioactive interactions, and transport of fission products in nuclear fuel is modified to describe the behavior of hydrogen and helium in irradiated nuclear fuel as well as to accumulate an expanded list of transuranium actinides. The program module developed on the basis of the model is included in the MFPR/R fuel code and the SFPR and the BERKUT-U fuel rod codes. The test calculations for mixed uranium-plutonium oxide fuel and mixed uranium-plutonium nitride fuel irradiated in fast reactors are in good agreement with high-precision neutronics calculations. [ABSTRACT FROM AUTHOR]

The paper analyzes a principal capability to transmute neptunium, the main component of transuranium radiowastes (TRW), in lead-cooled fast BREST-type reactor. High-energy neutron spectrum of the BREST-type fast reactor makes it possible either to eliminate neptunium in fission reactions or convert neptunium to plutonium with large fraction of 238Pu in radiative neutron capture reactions. According to the IAEA regulatory documents, plutonium containing above 80% 238Pu is regarded as an unsuitable material for manufacturing of nuclear explosive devices. Besides, good neutron-multiplying properties of 238Pu and 239Pu can prolong substantially the reactor core lifetime. Thus, introduction of neptunium into fresh fuel composition can eliminate the largest TRW fraction, strengthen regime of nuclear non-proliferation, produce some additional amount of thermal energy and prolong the reactor core lifetime. [ABSTRACT FROM AUTHOR]

The results of estimating the activity of the aerosol form and gaseous compounds of iodine isotopes in the ventilation system of the IVV-2M reactor facility are presented. The contribution of aerosol and gaseous forms of iodine to the total volumetric activity was simultaneously determined. Criteria of homogeneity of sorbed iodine compounds are determined on the basis of analysis of the dependence of the activity distribution in the layers of a multilayer filter. The study made it possible to determine the form in which radioactive iodine enters the space above the surface of the coolant of the water-moderated water-cooled pool-type research reactor. It is shown that the volumetric iodine activity in the air of the ventilation system of the reactor facility is generally determined by hardly sorbed gaseous compounds. [ABSTRACT FROM AUTHOR]

In this paper, we have developed a model for calculating of the fission rate and burnup in an uranium- gadolinium fuel (UGF) pellet. The heterogeneous fission rate distribution at beginning of life of the uranium-gadolinium fuel is shown to lead to the formation of a radial gradient of the porosity in the UGF pellet and to the heterogeneous radiation-induced densification of the fuel. We have also developed physical models of thermophysical properties of He, ZrO2, and zirconium cladding. Spatial and time temperature distributions in UGFE are calculated. [ABSTRACT FROM AUTHOR]

The goals of construction of the BIGR reactor, which was commissioned in 1977 at the All-Russian Scientific Research Institute of Experimental Physics, are reviewed. The primary avenues of research at BIGR are outlined. A brief description of the neutron-physics parameters of the reactor and the characteristic shapes of generated fission pulses is given. The possible sites for installation of objects to be irradiated are specified. Devices enhancing the irradiation capacity of the reactor are characterized. Current data on various research applications of the reactor are summarized. [ABSTRACT FROM AUTHOR]

Cesium, one of the heat-emitting fission elements contained in high active liquid waste, deserved separation. Calixbiscrown is a class of chemical compounds, promising in the cesium extraction. In this study, calix[4]-bis[(4-tert-butyl-1,2-phenylene)-crown-6] (CalixBBC for short) was synthesized by a multi-step scheme. The cesium extraction study was carried out using CalixBBC in two organic diluents such as chloroform and o-nitroanisole, which were used as electron-deficient and electron-rich surrogate dilutions, respectively. The effects of HNO3 concentration, mixing time, temperature were investigated using a batch technique. Comparing with chloroform, o-nitroanisole was in favor of cesium extraction. Both extractions strongly relied on HNO3 concentration in the range of 0.4-6.0 M. The pseudo-second-order model fitted the extractions well. Both extractions were spontaneous, exothermal processes. The foreigner metal ions showed little influence on the extraction. The stoichiometry of cesium and CalixBBC in the complex was 1:1. [ABSTRACT FROM AUTHOR]

The problem connected to the long-term storage of high-level nuclear waste has initiated an extensive search for suitable host rock formations and backfill materials to guarantee an isolation of hazardous nuclear elements from the biosphere for thousands of years. Besides other alternatives, clays and clayey materials have been in the focus of various sorption studies. With respect to long-term predictions of migration processes, the transuranium elements and fission products are of particular interest. The present review gives a detailed summary of sorption studies conducted during the past decades describing the impact of various geochemical parameters on the immobilization of Am(III) by different clays and clay minerals. [ABSTRACT FROM AUTHOR]

Purification of berkelium-249 (249Bk) at Oak Ridge National Laboratory requires a multi-step process with Bk Finishing as the final step. The current multi-process takes 6-7 months, including ~ 3 months spent on Bk Finishing. Recent trials of using columns of either LN resin or MP-1 anion exchange resin adsorbing the tetravalent 249Bk4+ in 8M HNO3-0.5M NaBrO3, followed by eluting impurities (e.g. Ce4+, Cf3+) and stripping 249Bk resulted in a new dual column method of selectively separating 249Bk from other trans-curium elements and fission product impurities, which is proposed to replace the current Bk Finishing with higher Bk purification efficiency and shorter processing period. This paper displays the experimental results and describes the dual column method with relevant chemistry issues. [ABSTRACT FROM AUTHOR]

Samarium-153 (153Sm) is a short-lived radionuclide that decays to stable europium-153 via beta emission, with subsequent de-excitation via gamma emission and internal conversion. Historical measurements of 153Sm by gamma spectrometry and beta liquid scintillation counting have shown a low bias compared to beta proportional counting. In order to investigate this, four national laboratories jointly conducted an experimental inter-comparison exercise on a certified 153Sm sample, created from neutron activation of samarium-152. Radiometric measurements were conducted using gamma spectrometry, liquid scintillation counting, gas proportional counting, and passivated implanted planar silicon detectors and compared across the four institutions against the certified value. The results from this experiment are presented together with a number of conclusions which suggest that the current published cumulative fission yield for 153Sm, as used by many laboratories, is approximately 15% high and is the likely cause of the previously observed bias. [ABSTRACT FROM AUTHOR]

This work explores a novel tomographic approach to PGAA that is both quantitative and spatially resolved, adapted from a clinical “proton beam range finder” in which MeV gamma rays are imaged by coincidence measurements of Compton scattered gamma rays with multi-detector arrays. We performed preliminary measurements using a Compton camera made with CdZnTe detector arrays on a series of test samples with high-energy (> 1 MeV) gamma emission lines. 3D image reconstructions were performed on the 2.2 MeV peak from H. The image reconstruction methods were also evaluated using the emission data generated by Monte Carlo simulations under ideal conditions. [ABSTRACT FROM AUTHOR]

An economics-mathematical model for performing analytical calculations of the present value of separative work for uranium isotopes in a separation plant currently being designed using gas centrifuge technology is examined. Analytical expressions are obtained for the present value of the separative work, the internal rate of return, and the payback period of the separation plant as a function of its main engineering and economics parameters - productivity (capacity), capital investment, and operating expenses. Calculations of these criteria for investment efficiency are presented for a wide range of initial data. It is shown that the calculation of the present value of separative work must be performed in a complex with other investment efficiency criteria in order to determine their optimal combination. [ABSTRACT FROM AUTHOR]

The history of the development and adoption of erbium fuel in RBMK is described. Research performed at the end of the 1980s - beginning of 1990s led to the conclusion that the optimal method of decreasing the steam coefficient of reactivity in RBMK is to add a consumable absorber - erbium. Computational and experimental work on the safety validation of the new fuel made it possible to adopt this fuel first in RBMK-1500 and then in RBMK-1000. The use of uranium-erbium fuel in RBMK made it possible to increase reactor safety, provide the requisite conditions for modernizing control rods, reduce the acuteness of the problem of storing spent fuel, and improve the economic indices of the fuel cycle. Considering the heightened interest in the use of erbium as a consumable absorber in VVER and some other reactors, the experience gained in developing and operating uranium-erbium fuel for RBMK could be helpful. [ABSTRACT FROM AUTHOR]

Delayed fission of atomic nuclei was discovered in 1966. It is observed primarily in odd-odd nuclei for which the energy released in beta decay (K capture) is commensurate with the fission barrier in the nucleus formed after this process. Delayed fission was found in four nuclide regions: neutrondeficient isotopes in the Pb region, neutron-deficient isotopes in the Ac and Pa regions, and neutrondeficient and neutron-rich isotopes of transuranium elements. In the wake of investigations into the properties of isotopes of superheavy transuranium elements, numerous calculations were performed in order to determine the masses of new nuclei and to predict their decay properties. Explored and predicted properties of superheavy-element nuclides, where, for some odd-odd nuclei of transuranium elements, the K-capture energy is commensurate with the fission barriers in the corresponding daughter nuclei formed after K capture, are analyzed. Estimates of the delayed-fission probability are presented for some isotopes of elements whose charge number Z ranges from 103 to 107. [ABSTRACT FROM AUTHOR]