Neutron Capture Research Articles

Mechanical properties and radiological implications of replacing sand with waste ceramic aggregate in ordinary concrete

The mining of aggregates for the production of concrete creates ecological problems. In this study, the effect of partially replacing sand as fine aggregate (FA) with waste ceramic tiles (WCT) on the density, compressive strength (CS), specific radioactivity of naturally occurring radioactive materials (238U, 232Th, and 40K), and the radiation shielding competence of concrete was investigated. Ordinary concrete samples consisting of cement, fine aggregate (river sand), coarse aggregate (granite), and water were prepared in 50 mm x 50 mm x 50 mm cubical steel moulds. The samples were coded as C-WCT0, C-WCT5, C-WCT10, C-WCT15, C-WCT20, and C-WCT25, representing concrete samples in which the FA component was replaced by 0, 5, 10, 15, 20, and 25% pulverized WCT, respectively. The CS and density of the samples were determined after 7-, 14-, and 28-day curing periods. The gamma spectrometric method was used to determine the specific activity of 238U, 232Th, and 40K using a hyper pure germanium detector. The photon and neutron shielding parameters of the concrete blocks were calculated with the aid of the EPICS2017 cross-section library and relevant standard formulae. The mean CS for each concrete category increase with curing age. The density of the concrete varied from 2213 kg/m3 to 2488 kg/m3 as the FA replacement level rose to 15%. Using WCT as a partial replacement for FA altered the chemical composition and decreased the specific activities of 238U, 232Th, and 40K, in the concrete samples. C-WCT15 had the best gamma photon and fast neutron absorption features among the concrete samples. The use of WCT as aggregate in concrete production is a sustainable and environmental-friendly way of producing concrete for general civil engineering and shielding applications in medical and other radiation facilities. This study also affirms that using alternative materials with lower specific activity to replace sand is radiologically desirable in reducing the indoor radiation dose of occupants of concrete-based structures. The replacement of 15% sand by WCT produced stronger, radiologically safer, and more effective radiation absorbing concrete.

Increased cell killing effect in neutron capture enhanced proton beam therapy

AbstractThermal neutrons generated in the body during proton beam therapy (PBT) can be used to cause boron neutron capture reactions and have recently been proposed as neutron capture enhanced PBT (NCEPBT). However, the cell killing effect of NCEPBT remains underexplored. Here, we show an increase in the cell killing effect of NCEPBT. Using Monte Carlo simulations, we showed that neutrons generated by proton beam irradiation are uniformly spread on tissue culture plates. Human salivary gland tumor cell line (HSG), human osteosarcoma cell line (MG63), human tongue squamous cell carcinoma cell line (SAS), and human malignant melanoma cell line (G-361) were irradiated with X-rays, proton beams, and proton beams with 10B-enriched boronophenylalanine (boron concentration of 20 and 80 ppm). The relative biological effectiveness (RBE) values of proton beams alone, proton beams with 20 ppm boron, and proton beams with 80 ppm boron for HSG, MG63, SAS, and G-361 were 1.02, 1.07, and 1.23; 1.01, 1.08, and 1.44; 1.05, 1.09, and 1.46; and 1.04, 1.13, and 1.63, respectively. NCEPBT with high boron concentration showed high RBE and a high sensitizing effect. Our results confirm an increase in the cell killing effect of NCEPBT, should aid in its clinical use, and warrant its further investigation.

Actinide Elemental Ratios of Spent Nuclear Fuel Samples by Resonance Ionization Mass Spectrometry.

While resonance ionization mass spectrometry (RIMS) has demonstrated utility in measuring isotopic compositions of elements in complex matrices without the need for chemical separation to remove isobaric interferences, it has had limited application in measuring elemental compositions. The ability to determine elemental compositions via an in situ method like RIMS would be an exceptional asset in spent nuclear fuel analysis, where they are important in assessing reactor histories and whose chemical separation presents a radiological hazard. However, quantitative elemental analysis by RIMS requires special considerations because each element is ionized by its own set of lasers tuned to element specific resonant ionization wavelengths. We present the first comprehensive study of measuring elemental ratios by RIMS in spent nuclear fuel. All actinides produced by neutron capture are enhanced significantly radially from the center to the edge of a fuel pellet. This edge effect is not readily accessible by conventional bulk measurements.

Strong absorptions of thermal neutrons caused by virtual states

Abstract Cross sections of compound nucleus (CN) formation by S-wave neutron scattering, which began to be studied in a pioneering work by Feshbach et al., are reanalyzed by the optical model plus the method of Jost function (JFM), which is one of modern theories to handle bound and unbound continuum states in a unified manner. We have calculated the CN cross-section for a thermal neutron scattering (En = 25.3 meV) by about 300 stable targets. The enhancements in the CN cross section at the specific mass number region, A ∼ 10, 50 and 160, which are well-known results in the previous optical model analyses, are reproduced by the present calculation. The JFM calculation is applied to investigate the origin of the enhanced CN cross-section, and the poles in the scattering matrices (S-matrices) are systematically explored in the complex momentum plane. In JFM, the S-matrix poles representing the virtual states, which are different from the usual resonances described by the Breit-Wigner formula, appear around the origin (zero energy) in the momentum plane at the mass region with the enhanced CN cross-section. The present analysis of the S-matrix means that the virtual state strongly enhances the CN cross-section. We also discuss the present results in connection to giant resonances and compound nuclear resonances, which were regarded as the established theories to understand the enhanced absorption of the thermal neutron in the previous studies.

Measurements of neutron capture cross-section for nuclides of interest in decommissioning (II): 58Fe(n,γ)59Fe

ABSTRACT As nuclear facilities are dismantled in decommissioning, large amounts of various waste are generated. Even more inconveniently, such waste is radioactive due to neutron activation. Thus, the neutron capture cross-sections of nuclides targeted in decommissioning are required to evaluate the radioactivity produced. In this work, 58Fe nuclide was selected among objective nuclides for decommissioning, and its thermal-neutron capture cross-section was measured by a neutron activation method at the graphite thermal column of Kyoto University Research Reactor in 5-MW operation. The thermal-neutron capture cross-section was derived using Westcott’s convention. The present work obtained 1.36 ± 0.03 barns for the58Fe(n,γ)59Fe reaction. The present result supports the JENDL-5 evaluation within 2σ. If updated with currently recommended nuclear data, some of the reported past data would support the present result.

Asymmetric Synthesis and Biological Evaluation of Both Enantiomers of 5- and 6-Boronotryptophan as Potential Boron Delivery Agents for Boron Neutron Capture Therapy

Asymmetric Synthesis and Biological Evaluation of Both Enantiomers of 5- and 6-Boronotryptophan as Potential Boron Delivery Agents for Boron Neutron Capture Therapy

TMET-13. SPATIAL METABOLOMIC CHANGES OF NUCLEOTIDE IN THE BRAINS OF ORTHOTOPIC MOUSE GLIOMA MODEL AFTER BORON NEUTRON CAPTURE THERAPY (BNCT)

Abstract Glioblastoma is the most lethal primary brain tumor. Boron Neutron Capture Therapy (BNCT) is a tumor-selective particle radiation therapy, in which high-LET α-particles and recoil 7Li are produced by the capture reaction between 10B and thermal neutrons and it has extended the prognosis of glioblastomas [Kawabata S, et al., Neuro-Oncology Advances 3(1), 1–9, 2021]. Augmented synthesis and use of nucleotide triphosphates is critical and universal metabolic dependency of tumor cells [Mullen, N.J., Singh, P.K. Nat Rev Cancer 23, 275–294 (2023)]. However, the effects of BNCT on metabolism of purine and pyrimidine in brain tumors and the surrounding normal brain are unknown. We spatially investigated metabolomic change in brains of orthotopic mouse glioma model, before and 2, 7, and 14 days after BNCT using mass spectrometry imaging (MSI). By separating tumor and non-tumor areas and performing Partial Least Squares Regression calculations, we have successfully visualized tumor-specific metabolites including adenine (ATP, ADP) and uridine (UTP, UDP-glucose, UDP-GlcNAc) with MSI. Of note, the signal of top-scored tumor specific metabolite, UDP-GlcNAc dramatically decreased and disappeared as the tumor regressed. Furthermore, the signal of ADP which was supposed to be released from tumor, colocalized with invading tumors along with corpus callosum. The value of adenylate energy charge, ([ATP]+0.5[ADP]/[ATP]+[ADP]+[AMP]) in the surrounding normal brain of the untreated tumor-bearing mouse increased up to 0.37 and decreased gradually down to 0.32 with BNCT, approaching to the value of normal control mouse brain, 0.27. These metabolomic changes reflected the tumor-killing effect and restoration of energy charge of surrounding normal brain by BNCT and have potential significance for development of biomarker or diagnosis.

Poly(vinyl alcohol) potentiating an inert D-amino acid-based drug for boron neutron capture therapy.

Since the discovery of D-amino acids, they have been considered inactive and have not been used as potent drugs. Here, we report that simple mixing with poly(vinyl alcohol) (PVA) unleashed latent potentials of D-amino acids in boron neutron capture therapy (BNCT). PVA formed boronate esters with seemingly useless boronated D-amino acids and induced tumor-associated amino acid transporter-superselective internalization and prolonged intracellular retention, accomplishing complete cure of tumors. The superselective internalization was achieved by switching the internalization pathway from ineffective pass through the transporter to the transporter-mediated endocytosis. The acidic environment in the endo-/lysosome dissociated the boronate esters and elicited the stealthiness of the drugs, preventing their externalization and prolonging intracellular retention time. In a subcutaneous tumor model, this system accomplished surprisingly high tumor-selective accumulation that could not be achieved by conventional approaches and induced drastic BNCT effects. PVA may be a unique material to unlock potentials of seemingly inert molecules.

Toroidal torques due to n=1 magnetic perturbations in ITER baseline scenario

Abstract Toroidal torques, generated by the resonant magnetic perturbation (RMP) and acting on the plasma column, are numerically systematically investigated for an ITER baseline scenario. The neoclassical toroidal viscosity (NTV), in particular the resonant portion, is found to provide the dominant contribution to the total toroidal torque under the slow plasma flow regime in ITER. While the electromagnetic torque always opposes the plasma flow, the toroidal torque associated with the Reynolds stress enhances the plasma flow independent of the flow direction. A peculiar double-peak structure for the net NTV torque is robustly computed for ITER, as the toroidal rotation frequency is scanned near the zero value. This structure is found to be ultimately due to a non-monotonic behavior of the wave-particle resonance integral (over the particle pitch angle) in the superbanana plateau NTV regime in ITER. These findings are qualitatively insensitive to variations of a range of factors including the wall resistivity, the plasma pedestal flow and the assumed frequency of the rotating RMP field.

Event-based high-resolution neutron image formation analysis using intensified CMOS cameras

We present a versatile optical setup for high-resolution neutron imaging with an adaptable field of view and magnification that can resolve individual neutron absorption events with an image intensifier and a CMOS camera. Its imaging performance is characterized by evaluating the resolution limits of the individual optical components and resulting design aspects are discussed. Neutron radiography measurements of a Siemens star pattern were performed in event mode acquisition comparing two common high-resolution neutron scintillators, crystalline Gadolinium Gallium Garnet (GGG) and powdered Gadolinium Oxysulfide (GOS). An analysis of the light signature caused by neutron absorption events is performed and some resulting issues for both GGG and GOS regarding optical system design are addressed. Both scintillators reach similar resolution (4–5 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\upmu }$$\\end{document}m) in event mode acquisition despite different light emission characteristics. The findings suggest that, in the case of GOS, the resolution is limited by the size of the light clusters which in turn originate from the photon scattering at the boundaries of the powder particles comprising it, while with GGG the lower light conversion efficiency makes it challenging to collect enough photons to trigger sufficient signal amplification in the image intensifier. Overall, the proposed event-based evaluation of scintillators allows for quantifying and optimizing various design parameters, which is much more complex than adopting conventional methods based on integrated images.

Hazard, risk, reliability assessment and improvement of Darlington Tritium Removal Facility (DTRF) cryogenic refrigeration system

Tritium is a radioactive isotope of hydrogen, produced in heavy water, during CANDU reactor operations by neutron absorption. The tritium removal facility at Darlington (DTRF) is used to extract tritium from the heavy water on a continuous basis and concentrates it in preparation for immobilization and storage. There are several internal and external hazards associated with the operation of DTRF, such as fires, onsite transportation accidents, exposure to radioactive materials, explosion due to Hydrogen (H2) and the release of radioactive substances from the Tritium Immobilization System. This paper conducts a risk analysis for the DTRF Cryogenic Refrigeration System, associated with both Low and High Tritium Distillation columns. This study includes hazard identification, consequence analysis and risk estimation. Fault Tree and Event Tree Analysis conducted, system reliability, availability and human reliability was considered. Consequently, methods for risk reduction and integration with improvement to CRS design is discussed.

Carborane-based BODIPY dyes: synthesis, structural analysis, photophysics and applications

Icosahedral boron clusters-based BODIPY dyes represent a cutting-edge class of compounds that merge the unique properties of boron clusters with the exceptional fluorescence characteristics of BODIPY dyes. These kinds of molecules have garnered substantial interest due to their potential applications across various fields, mainly including optoelectronics, bioimaging, and potential use as boron carriers for Boron Neutron Capture Therapy (BNCT). Carborane clusters are known for their exceptional stability, rigid geometry, and 3D-aromaticity, while BODIPY dyes are renowned for their strong absorption, high fluorescence quantum yields, and photostability. The integration of carborane into BODIPY structures leverages the stability and versatility of carboranes while enhancing the photophysical properties of BODIPY-based fluorophores. This review explores the synthesis and structural diversity of boron clusters-based BODIPY dyes, highlighting how carborane incorporation can lead to significant changes in the electronic and optical properties of the dyes. We discuss the enhanced photophysical characteristics, such as red-shifted absorption and emission poperties, charge and electronic transfer effects, and improved cellular uptake, resulting from carborane substitution. The review also delves into the diverse applications of these compounds. In bioimaging, carborane-BODIPY dyes offer superior fluorescence properties and cellular internalization, making them ideal for cell tracking. In photodynamic therapy, (PDT) these dyes can act as potent photosensitizers capable of generating reactive oxygen species (ROS) for targeted cancer treatment making them excellent candidates for PDT. Additionally, their unique electronic properties make them suitable candidates for optoelectronic applications, including organic light-emitting diodes (OLEDs) and sensors. Overall, carborane-BODIPY dyes represent a versatile and promising class of materials with significant potential for innovation in scientific and technological applications. This review aims to provide a comprehensive overview of the current state of research on carborane-BODIPY dyes, highlighting their synthesis, properties, and broad application spectrum.

Cold‐Sprayed Boron‐Nitride‐Nanotube‐Reinforced Aluminum Matrix Composites with Improved Wear Resistance and Radiation Shielding

In this study, the influence of cold‐spray processing on the integration of 1D boron nitride nanotubes (BNNTs) into aluminum (Al) matrix composite deposits is delved into. Successful deposition of Al‐BNNT composite is achieved by pre‐spray dispersion of BNNTs in Al powder via wet mixing aided by ultrasonication. Pure Al powder deposition at 380 °C is limited by nozzle clogging, restricting the deposit thickness to 0.2 mm, while the presence of BNNTs enables longer spraying due to nozzle cleaning and damping by hard BNNTs, allowing thicker Al‐BNNT deposits of about 2 mm. Microstructural analysis reveals severely deformed Al splats decorated with a uniformly distributed network of BNNTs at the intersplat boundaries, reducing the porosity from 8% to 4% and increasing the splat flattening by 40%. Tribological testing demonstrates resistance of BNNTs to normal force, resulting in a 21% improvement in coefficient of friction and a 65% reduction in wear volume in the Al‐BNNT composite. Additionally, incorporating 3 vol.% BNNTs enhances the neutron radiation shielding by 35%. These improvements in the composites are attributed to reduced porosity and the inherent properties of BNNTs, such as high strength, the ability to produce tribofilm lubrication during dry sliding wear, and their high neutron absorption cross‐sectional area.

S-process nucleosynthesis in chemically peculiar binaries

Context. Around half of the heavy elements in the Universe are formed through the slow neutron capture (s-) process, which takes place in thermally pulsing asymptotic giant branch (AGB) stars with masses of 1 − 6 M⊙. The nucleosynthetic imprint of the s-process can be studied by observing the material on the surface of binary barium (Ba), carbon (C), CH, and carbon-enhanced metal-poor (CEMP) stars. Aims. We study the s-process by observing the luminous components of binary systems polluted by a previous AGB companion. Our radial velocity (RV) monitoring program establishes an ongoing collection of binary stars exhibiting enrichment in s-process material for the study of elemental abundances, the production of s-process material, and binary mass transfer. Methods. From high-resolution optical spectra, we measured RVs for 350 stars and derived stellar parameters for approximately 150 stars using ATHOS. For a subsample of 24 chemically interesting stars, we refined our atmospheric parameters using ionization and excitation balance with the Xiru program. We used the MOOG code to compute one-dimensional local thermodynamic equilibrium (1D-LTE) abundances of carbon, magnesium, s-process elements (Sr, Y, Zr, Mo, Ba, La, Ce, Nd, Pb), and Eu to investigate neutron capture events and stellar chemical composition. We estimated dynamical stellar masses via orbital optimization using Markov chain Monte Carlo techniques in the ELC program, and we compared our results with low-mass AGB models in the FUll-Network Repository of Updated Isotopic Tables & Yields (FRUITY) database. Results. In our abundance subsample, we find enhancements in s-process material in spectroscopic binaries, a signature of AGB mass transfer. We add the element Mo to the abundance patterns, and for 12 stars we add Pb detections or upper limits, as these are not known in the literature. Computed abundances are in general agreement with the literature. Comparing our abundances to dilution-modified FRUITY yields, we find correlations in s-process enrichment and AGB mass, which are supported by dynamical modeling from RVs. Conclusions. From our high-resolution observations, we expand heavy element abundance patterns and highlight binarity in our chemically interesting systems. We find trends in s-process element enhancement from AGB stars, and agreement between theoretical and dynamically modeled masses. We investigate evolutionary stages for a small subset of our stars.

Nursing care for patients with recurrent invasive meningioma undergoing salvage boron neutron capture therapy: a case report

Nursing care for patients with recurrent invasive meningioma undergoing salvage boron neutron capture therapy: a case report

Design and Construction of Experimental System for Validation of a New Image Reconstruction Technique with Limited-view-angle Projection Data for BNCT-SPECT

Abstract. Boron Neutron Capture Therapy (BNCT) is expected to be a promising radiation therapy for cancer, and research on various issues associated with it is still in progress. One of the unsolved issues is the construction of a system for observing the effect of the treatment (local boron dose) in real time under high-background circumstances. Thus, we set out to establish a method for measuring gamma-rays emitted promptly from the body following the boron neutron capture reaction and reconstructing images in a SPECT-like manner. We call this method BNCT-SPECT. We have been developing a new image reconstruction method based on Bayesian estimation for the BNCT-SPECT method. In the present study, the aims were to design and construct an experimental system capable of validating BNCT-SPECT and its image reconstruction method and to confirm BNCT-SPECTs performance. The crucial takeaway from this study is that we should consider the use of extremely high background radiation during BNCT. For the validation of BNCT-SPECT, we attempted to reproduce these conditions, despite this being quite challenging. We first constructed an experimental system capable of reproducing such conditions. Theoretical investigation was carried out to facilitate the design of the system using the Monte Carlo transport calculation code MCNP. Finally, we performed experiments with some standard gamma-ray sources to complete the system.

Fabrication and Radiation Shielding Properties of (HDPE/Colemanite)‐(HDPE/Bi2O3) Multi‐Layer Composites

ABSTRACTIn this study, 5, 10, and 15 wt% colemanite (Ca2B6O11‐5H2O) and 15 wt% Bi2O3 filled high‐density polyethylene (HDPE) composites were fabricated by conventional melt extrusion processing techniques in the form of a layered structure to absorb both neutron radiation and secondary radiation resulting from neutron‐induced reactions. In the layered structure, HDPE was used to slow down neutrons, while colemanite and Bi2O3 were used to trap thermal neutrons and secondary gamma radiation respectively. The properties of the colemanite/HDPE and Bi2O3/HDPE composites were investigated by scanning electron microscopy (SEM), x‐ray diffraction (XRD), and thermogravimetric analysis (TGA). The mechanical properties (tensile and hardness) of the composites were also investigated. The results showed that the addition of colemanite and Bi2O3 particles did not significantly alter the thermal and mechanical properties of the HDPE composites. The total macroscopic cross‐section of the composites was determined using a 239Pu‐Be (α,n) neutron source, while their linear and mass attenuation coefficients were determined using a 137Cs gamma‐ray source. The material with the best neutron absorption rate is 15 wt% colemanite‐filled HDPE (2.31 ± 003 cm−1), while the best gamma‐absorbing material is 15 wt% Bi2O3 filled HDPE (0.114 cm−1). The 15 wt% colemanite, 15 wt% Bi2O3 doped HDPE layered structure has 1.72 ± 0.05 cm−1 macroscopic cross‐sections and 0.098 linear attenuation coefficient. The results show that filled colemanite HDPE composites improve neutron shielding properties and Bi2O3 filled HDPE composites provide good shielding performance for gamma rays.

Machine learning-enabled design of Fe-based bulk metallic glasses for superior thermal neutron absorption properties

Machine learning-enabled design of Fe-based bulk metallic glasses for superior thermal neutron absorption properties

Neutron capture cross-section of p-nucleus 74Se in the keV region using the activation method

Neutron capture cross-section of p-nucleus 74Se in the keV region using the activation method

A Comprehensive Study of Open Cluster Chemical Homogeneity Using APOGEE and Milky Way Mapper Abundances

Stars in an open cluster are assumed to have formed from a broadly homogeneous distribution of gas, implying that they should be chemically homogeneous. Quantifying the level to which open clusters are chemically homogeneous can therefore tell us about interstellar medium pollution and gas mixing in progenitor molecular clouds. Using Sloan Digital Sky Survey (SDSS)-V Milky Way Mapper and SDSS-IV Apache Point Observatory Galaxy Evolution Experiment DR17 abundances, we test this assumption by quantifying intrinsic chemical scatter in up to 20 different chemical abundances across 26 Milky Way open clusters. We find that we can place 3σ upper limits on open cluster homogeneity within 0.02 dex or less in the majority of elements, while for neutron capture elements, as well as those elements having weak lines, we place limits on their homogeneity within 0.2 dex. Finally, we find that giant stars in open clusters are ∼0.01 dex more homogeneous than a matched sample of field stars.