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In this research, curium oxide (CmO2) is studied as fuel for VVER-1200 reactor to get an attention to its energy value and possibilities. For this purpose, CmO2 is used in fuel rods or integrated burnable absorber (IBA) rods with and without UO2 and then compared with the conventional fuel assembly of VVER-1200 reactor. It is burned to 60 GWd/t by using SRAC-2006 code and JENDL-4.0 data library. From these studies, it is found that CmO2 is competent like UO2 as a fuel due to higher fission cross-section of 243Cm and 245Cm isotopes and neutron capture cross-section of 244Cm and 246Cm isotopes. As a result, when some or all of the UO2 of fuel rods or IBA rods are replaced by CmO2, we get a similar k-inf like the reference even with lower enrichment UO2 fuels. These studies show that the use of CmO2 as IBA rods is more effective than the fuel rods considering the initially loaded amount, power peaking factor (PPF), fuel temperature and void coefficient, and the quality of spent fuel. From a detailed study, 3% CmO2 with inert material ZrO2 in IBA rods are recommended for the VVER-1200 reactor assembly from the once through concept.

PURPOSE A new type of electronic dosimeter is presented, capable of discerning between the doses of gamma photons and neutrons in a mixed beam as found in Boron Neutron Capture Therapy (BNCT). We introduce a real-time dosimeter based on a thick gate Field Oxide Field Effect Transistor (FOXFET) covered with a neutron converter layer containing gadolinium. METHODS To sensitize the FOXFET dosimeter to neutron fluxes, a converter layer containing gadolinium oxide particles embedded in photoresines was deposited over the sensor surface. Mixed neutron-gamma field configurations with different neutron energy spectra were used to assess the FOXFET response, considering different thicknesses of the neutron converter layer. RESULTS The total gamma sensitivity of the devices resulted to be 43 mV/Gy. The responses of sensors with different converter layer thicknesses irradiated with different neutron spectra are simulated using GEANT4 code. The response to photons is not significantly modified with thin conversion layers when used in water medium. CONCLUSIONS A real-time dosimeter comprising a pair of FOXFET sensors-only one of them with a gadolinium neutron converter layer -allows the simultaneous measurement of gamma dose and neutron flux during BNCT irradiations. This article is protected by copyright. All rights reserved.

Journal of radioanalytical and nuclear chemistry (2021). doi:10.1007/s10967-021-08102-2, Published by Springer Science + Business Media B.V., Dordrecht [u.a.]

In this study, molecular interactions of prostate-specific membrane antigen (PSMA) with five chemically distinct urea-based boron-containing inhibitors have been investigated at the atomic level using molecular docking and molecular dynamics simulations. The PSMA–inhibitor complexations have been analyzed by comparing their binding modes, secondary structures, root-mean-square deviations, noncovalent interactions, principal components, and binding free energies. PSMA is a cell surface glycoprotein upregulated in cancerous cells and can be targeted by boron-labeled inhibitors for boron neutron capture therapy (BNCT). The effective BNCT requires the selective boron delivery to the tumor area and highly specific PSMA-mediated cellular uptake by tumor. Thus, a potent inhibitor must exhibit both high binding affinity and high boron density. The computational results suggest that the chemical nature of inhibitors affects the binding mode and their association with PSMA is primarily dominated by hydrogen bonding, salt bridge, electrostatic, and π–π interactions. The binding free energies (−28.0, −15.2, −43.9, −23.2, and −38.2 kcal/mol) calculated using λ-dynamics for all inhibitors (In1–5) predict preferential binding that is in accordance with experimental data. Among all inhibitors, In5 was found to be the best candidate for BNCT. The binding of this inhibitor to PSMA preserved its overall secondary structure. These results provide computational insights into the coordination flexibility of PSMA and its interaction with various inhibitors. They can be used for the design and synthesis of efficient BNCT agents with improved drug selectivity and high boron percentage.

10B-neutron capture was observed optically using a boron-added liquid scintillator. Trimethyl borate was dissolved in a commercially available liquid scintillator at natural boron concentrations of approximately 1 wt% and 0.25 wt%. The boron-added liquid scintillator was placed in a phantom quartz bottle and irradiated by thermal neutrons (~ 105 n/[cm2 s]) for 150, 300, and 600 s. The luminescence of the liquid scintillator was clearly observed using a cooled charge-coupled device (CCD) camera during irradiation. The luminance value recorded by the CCD camera was proportional to the duration of irradiation by thermal neutrons. The luminescence distribution showed reasonable agreement with that of energy deposition by Li and alpha particles from 10B-neutron capture reactions calculated via Monte Carlo simulations. When trimethyl borate was not dissolved in the liquid scintillator (0 wt% natural boron), no visible luminescence was observed even after 600 s of irradiation. These findings demonstrate that the observed luminance originates from the Li and alpha particles generated by 10B-neutron capture reactions. Consequently, the luminescence distribution is directly related to the boron dose of the liquid scintillator. To the best of our knowledge, direct experimental optical observations of boron dose distribution have not yet been reported. This novel technique will be useful for quality assurance in boron neutron capture therapy (BNCT) because instantaneous neutron irradiation may be sufficient for the observing the intense neutron beam used in clinical BNCT (~ 109 n/[cm2 s]), and quick evaluation of the boron dose distribution is expected to be feasible.

Introduction Boron neutron capture therapy (BNCT) is a biologically targeted, cell-selective particle irradiation therapy that utilizes the nuclear capture reaction of boron and neutron. Recently, accelerator neutron generators have been used in clinical settings, and expectations for developing new boron compounds are growing. Methods and Results In this study, we focused on serum albumin, a well-known drug delivery system, and developed maleimide-functionalized closo-dodecaborate albumin conjugate (MID-AC) as a boron carrying system for BNCT. Our biodistribution experiment involved F98 glioma-bearing rat brain tumor models systemically administered with MID-AC and demonstrated accumulation and long retention of boron. Our BNCT study with MID-AC observed statistically significant prolongation of the survival rate compared to the control groups, with results comparable to BNCT study with boronophenylalanine (BPA) which is the standard use of in clinical settings. Each median survival time was as follows: untreated control group; 24.5 days, neutron-irradiated control group; 24.5 days, neutron irradiation following 2.5 h after termination of intravenous administration (i.v.) of BPA; 31.5 days, and neutron irradiation following 2.5 or 24 h after termination of i.v. of MID-AC; 33.5 or 33.0 days, respectively. The biological effectiveness factor of MID-AC for F98 rat glioma was estimated based on these survival times and found to be higher to 12. This tendency was confirmed in BNCT 24 h after MID-AC administration. Conclusion MID-AC induces an efficient boron neutron capture reaction because the albumin contained in MID-AC is retained in the tumor and has a considerable potential to become an effective delivery system for BNCT in treating high-grade gliomas.

Boron neutron capture therapy (BNCT) was first proposed as early as 1936, and research on BNCT has progressed relatively slowly but steadily. BNCT is a potentially useful tool for cancer treatment that selectively damages cancer cells while sparing normal tissue. BNCT is based on the nuclear reaction that occurs when 10B capture low-energy thermal neutrons to yield high-linear energy transfer (LET) α particles and recoiling 7Li nuclei. A large number of 10B atoms have to be localized within the tumor cells for BNCT to be effective, and an adequate number of thermal neutrons need to be absorbed by the 10B atoms to generate lethal 10B (n, α)7Li reactions. Effective boron neutron capture therapy cannot be achieved without appropriate boron carriers. Improvement in boron delivery and the development of the best dosing paradigms for both boronophenylalanine (BPA) and sodium borocaptate (BSH) are of major importance, yet these still have not been optimized. Here, we present a review of this treatment modality from the perspectives of radiation oncology, biology, and physics. This manuscript provides a brief introduction of the mechanism of cancer-cell-selective killing by BNCT, radiobiological factors, and progress in the development of boron carriers and neutron sources as well as the results of clinical study.

The aim of the NEPTUNE (Nuclear process-driven Enhancement of Proton Therapy UNravEled) project is to investigate in detail both the physical and radiobiological phenomena that could justify an increase of the proton-induced cytogenetic effects in cells irradiated in presence of an agent containing natural boron. In this work, a double-stage silicon telescope coupled to different boron converters was irradiated at the CATANA proton therapy facility (INFN-LNS) for studying the proton boron fusion and the neutron boron capture reactions by discriminating secondary particles from primary protons. Different boron targets were developed by depositing boric acid, enriched with a higher than 99% content of 10B or 11B, on a 50 µm thick PolyMethilMetacrylate (PMMA) substrate. The 10B target allows to evaluate the contribution of lithium and alpha particles produced by the boron neutron capture reaction triggered by secondary thermal neutrons, while the 11B target is exploited for studying the effect of the p + 11B → 3α nuclear reaction directly triggered by primary protons. Experimental results clearly show the presence of alpha particles from both the reactions. The silicon telescope is capable of discriminating, by means of the so-called “scatter plots”, the contribution of alpha particles originated by thermal neutrons on 10B with respect to the ones produced by protons impinging on 11B. Although a reliable quantitative study of the alpha production rate has not been achieved yet, this work demonstrates that low energy and, therefore, high-LET particles from both the reactions can be measured.

Reliable data on 7Li(p,p'γ)7Li reaction cross section and photon yield from a thick lithium target are important for many applications including boron neutron capture therapy of malignant tumors. Experimental data on cross section differ greatly from one author to another; experimental data on photon yield are extremely scarce. Measurements of the reaction cross section and photon yield were carried out at the accelerator-based neutron source at the Budker Institute of Nuclear Physics (Novosibirsk, Russia) using a NaI and HPGe γ-ray spectrometers. The 7Li(p,p'γ)7Li reaction cross section and 478 keV photon yield from a thick lithium target at proton energies from 0.65 MeV to 2.225 MeV have been measured with high accuracy. The data obtained are presented in the form of tables.

Organoboron compounds have been playing an increasingly important role in analytical chemistry, material science, health applications, and particularly as functional polymers like boron carriers for cancer therapy. There are two main applications of boron isotopes in radiation cancer therapy, Boron Neutron Capture Therapy and Proton Boron Fusion Therapy. In this study, a novel and original material consisting of a three-dimensional polymer network crosslinked with $$^{10}$$ 10 B enriched boric acid molecules is proposed and synthesized. The effects of the exposition to thermal neutrons were studied analyzing changes in the mechanical properties of the proposed material. Dedicated Monte Carlo simulations, based on MCNP and FLUKA main codes, were performed to characterize interactions of the proposed material with neutrons, photons, and charged particles typically present in mixed fields in nuclear reactor irradiations. Experimental results and Monte Carlo simulations were in agreement, thus justifying further studies of this promising material.

There has recently been intense research on boron nitride (BN)-based materials for radiation shielding, including shielding neutron radiations from nuclear reactors. However, advanced materials should display more than just radiation-shielding functions to be considered to be an outstanding candidate for applications in space; consequently, multifunctional BN-based materials with high hydrogen intake have been found to provide sufficient shielding properties. This article reviews the BN nanostructures and BN-based materials for space radiation-shielding application. It begins with a brief introduction of BN structures and their physical properties and followed by an emphasis on radiation-shielding properties of BN as related to neutron capture and hydrogen storage. In addition, development of BN-based materials for a space radiation-shielding application is discussed.

The IRT-T reactor has been conducting research in the field of irradiation of ingots of single-crystal semiconductor materials since 1987. The article describes the existing silicon doping facility. The results of studies on the possibility of creating an additional irradiation channel for neutron-transmutation doping of silicon are presented. It is shown that the use of a graphite reflector and a thermal neutron filter based on boron makes it possible to achieve non-uniformity of irradiation up to 5 %. The principal possibility of irradiating single-crystal silicon ingots with a diameter of up to 203 mm and a length of up to 500 mm is shown. The questions of optimizing the configuration of the core and the regime of reactors operation for increasing the neutron flux in the irradiation channels are discussed. In addition, applying the facility to produce base materials for neutron dosimeter in neutron capture therapy studies is proposed.

The compound 4-dihydroxyboryl-l-phenylalanine (BPA) has found use in clinical trials of boron neutron capture therapy (BNCT). Here, we have examined the interaction with DNA of an amide-blocked BPA derivative of hexa-l-arginine (Ac-BPA-Arg6-NH2). Physical and spectroscopic assays show that this peptide binds to and condenses DNA. The resulting condensates are highly resistant to the effects of nuclease incubation (68-fold) and gamma (38-fold) irradiation. Radioprotection was modeled by Monte Carlo track structure simulations of DNA single strand breaks (SSBs) with TOPAS-nBio. The differences between experimental and simulated SSB yields for uncondensed and condensed DNAs were ca. 2 and 18%, respectively. These observations indicate that the combination of a plasmid DNA target, the BPA-containing peptide, and track structure simulation provides a powerful approach to characterize DNA damage by the high-LET radiation associated with neutron capture on boron.

Fundamentals of boron neutron capture therapy of malignant tumors are outlined, and the current status of the development of epithermal-neutron sources on the basis of charged-particle accelerators is surveyed. Attention is additionally given to a neutron source based on a charged-particle accelerator belonging to a new type—a tandem accelerator with vacuum insulation and a lithium neutron-producing target.

Background: Due to the noninvasive nature of boron neutron capture therapy (BNCT), it is considered a promising cancer treatment method. Aim: To investigate whether polyvinyl alcohol/boric acid crosslinked nanoparticles (PVA/BA NPs) are an efficient delivery system for BNCT. Materials & methods: PVA/BA NPs were synthesized and cocultured with brain and oral cancers cells for BNCT. Results: PVA/BA NPs had a boron-loading capacity of 7.83 ± 1.75 w/w%. They accumulated in brain and oral cancers cells at least threefold more than in fibroblasts and macrophages. The IC50 values of the brain and oral cancers cells were at least ninefold and sixfold lower than those of fibroblasts and macrophages, respectively. Conclusion: Theoretically, PVA/BA NPs target brain and oral cancers cells and could offer improved therapeutic outcomes of BNCT.

The photon and neutron absorbing capacity of titanate-doped borate glasses: 65B(2)O(3)-30Li(2)O-5Al(2)O(3)-xTiO(2): x = 0-30 mol% coded as G1-G7 were investigated via WinXCOM and EXABCal computer codes. Mass (mu(m)) and linear (LAC) attenuation coefficients, mean-free path (MFP), half-value thickness (HVT), buildup factors (EABUF and EBUF), and the relative fast neutron absorbing efficacy were investigated. The maximum value of mu(m) at 15 keV was 1.68, 2.976, 4.119, 5.134, 6.042, 6.856, and 7.593 cm(2)/g for G1, G2, G3, G4, G5, G6, and G7, respectively. For energies below 0.1 MeV and above 10 meV, mu(m) values vary according to the order (G1)(mu m) < (G2)(mu m) < (G3)(mu m) < (G4)(mu m) < (G5)(mu m) < (G6)(mu m) < (G7)(mu m). Values of LAC followed the order: (G7)(LAC) > (G6)(LAC) > (G5)(LAC) > (G4)(LAC) > (G3)(LAC) > (G2)(LAC) > (G1)(LAC). The trend of the MFP increases among the glasses follows a reverse order as that of LAC: (G1)(MFP) > (G2)(MFP) > (G3)(MFP) > (G4)(MFP) > (G5)(MFP) > (G6)(MFP) > (G7)(MFP). The HVT of the glasses follow the order: (G1)(HVT) > (G2)(HVT) > (G3)(HVT) > (G4)(HVT) > (G5)(HVT) > (G6)(HVT) > (G7)(HVT). EABUF and EBUF increase in the order (G1)((EABUF, EBUF)) > (G2)((EABUF, EBUF)) > (G3)((EABUF, EBUF)) > (G4)((EABUF, EBUF)) > (G5)((EABUF, EBUF)) > (G6)((EABUF, EBUF)) > (G7)((EABUF, EBUF)). The investigated glasses (G1-G7) are better fast neutron absorbers compared to ordinary concrete and water. Results revealed that higher titanate doping concentrations produced better photon and fast neutron shielding capacities. Therefore, the investigated glasses showed superior shielding efficacy when compared with some traditional shielding materials; consequently, the G1-G7 glasses are recommended for use as ionizing radiation shields.

The Kansai BNCT Medical Center has a cyclotron based epithermal neutron source for clinical Boron Neutron Capture Therapy. The system accelerates a proton to an energy of 30 MeV which strikes a beryllium target producing fast neutrons which are moderated down to epithermal neutrons for BNCT use. While clinical studies in the past have shown BNCT to be highly effective for malignant melanoma of the skin, to apply BNCT for superficial lesions using this system it is necessary to shift the thermal neutron distribution so that the maximum dose occurs near the surface. A dose distribution shifter was designed to fit inside the collimator to further moderate the neutrons to increase the surface dose and reduce the dose to the underlying normal tissue. Pure polyethylene was selected, and a Monte Carlo simulation was performed to determine the optimum thickness of the polyethylene slab. Compared with the original neutron beam, the shifter increased the thermal neutron flux at the skin by approximately 4 times. The measured and simulated central axis depth distribution and off axis distribution of the thermal neutron flux were found to be in good agreement. Compared with a 2 cm thick water equivalent bolus, a 26% increase in the thermal neutron flux at the surface was obtained, which would reduce the treatment time by approximately 29%. The DDS is a safe, simple and an effective tool for the treatment of superficial tumours for BNCT if an initially fast neutron beam requires moderation to maximise the thermal neutron flux at the tissue surface.

Non-uranium production of 99Mo via neutron capture or by photonuclear reaction using an electron accelerator is receiving considerable attention. For commercial production of 99Mo, post-irradiation processes must incorporate a robust design for easy scale-up. Once developed, large-scale chemical processes must be optimized for hot-cell operations and potential automation. Here we present experimental results on the large-scale dissolution of sintered Mo disks using three 50% hydrogen peroxides from different suppliers. Dissolution rates obtained for 600-g Mo batches and potential reasons for different dissolution behaviors is discussed.

Nuclear energy is the leading clean energy source in the United States with 99 nuclear power plants generating approximately 20% of the country’s electricity. While the growth of the industry helps to reduce our reliance on fossil fuels, there is also an increase in nuclear waste. The demand for on-site dry cask spent nuclear fuel storage has increased due to complications with the Yucca Mountain Project and diminishing pool capacity. A novel dry cask consisting of an aluminum metal matrix for effective thermal conductivity with boron carbide as a neutron absorbing additive was investigated using gravity sand casting techniques. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and optical microscopy were used to characterize the resultant microstructure, including boron carbide incorporation and heterogeneity. Results indicate vortex and nonvortex mixing in air with boron carbide (1–10 µm diameter) produces large amounts of porosity and insufficient wetting. Use of a larger particle size distribution of boron carbide (20–60 µm diameter) during high speed vortex mixing prior to casting has shown significant dispersion of up to 12 wt% sufficient for neutron shielding with appropriate wall thickness. These results validate the use of gravity sand casting as a means to produce borated aluminum for an effective alternative to fuel storage.

The neutron capture cross sections of 244Cm and 246Cm were measured for the neutron energy range of 1–1000 eV via the neutron time-of-flight method with Accurate Neutron-Nucleus Reaction measurem...

Background/Aim: Tumor cell destruction by boron neutron capture therapy (BNCT) is attributed to the nuclear reaction between (10)B and thermal neutrons. The accumulation of (10)B atoms in tumor cells without affecting adjacent healthy cells is crucial for effective BNCT. We previously reported that several types of liposomal boron delivery systems (BDS) delivered effective numbers of boron atoms to cancer tissues, and showed tumor-growth suppression after thermal neutron irradiation. In the present study, we examined the effects of BNCT after intra-arterial infusion of (10)B-borono-dodecaborate ((10)BSH) by liposomal BDS in rabbit hepatic cancer models. Materials and Methods: We prepared (10)BSH-entrapped transferrin-conjugated polyethylene glycol liposomes constructed with distearoyl-boron lipid (TF-PEG-DSBL), and performed thermal neutron irradiation at the Kyoto University Institute for Integrated Radiation and Nuclear Science after intra-arterial infusion into rabbit VX-2 hepatic tumors. Results: Concentrations of (10)B in VX-2 tumors on delivery with TF-PEG-DSBL liposomes reached 25 ppm on day 3 after the injection. Tumor growth was suppressed by thermal neutron irradiation after intra-arterial injection of this (10)BSH-containing liposomal BDS, without damage to normal cells. Conclusion: The present results demonstrate the applicability of (10)B-containing TF-PEG-DSBL liposomes as a novel intra-arterial boron carrier in BNCT for cancer.

A reliable copper-mediated nucleophilic radiosynthesis of the PET imaging probe [18F]FBPA was developed using novel aryldiboron precursors. The carrier-free [18F]FBPA with radiochemical purity >99% was prepared routinely via the two-step synthesis with an automatic module and can be used for clinical PET imaging of tumours.

Carboxyboranylamino ethanol (Me2N(BH2CO2H)CH2CH2OH, 1) was prepared in 75.0% yield by an amine-exchange reaction. Compound 1 shows lower cytotoxicity and higher anti-tumor efficacy in vitro towards the SCCVII cell line in comparison with 4-borono-L-phenylalanine (BPA) and methyl 2-hydroxyl-5-(1'-ortho-carbonylmethyl-1',2',3'-triazol-4'-yl)-benzonate (2). The bio-enhancement is interpreted using molecular docking calculations.

A neutron source composed of a tandem accelerator with vacuum insulation and a lithium target is used to develop the boron neutron capture therapy and other applications. The dependence of the proton beam size on the target surface on the beam current is measured with thermocouples inserted inside the target and with a infrared camera. It is found that there is no appreciable influence of the spatial charge on the proton beam transport to a distance of 5 m from the accelerator to the target, which simplifies the neutron source operation.

The paper discusses dynamics of charged particles and neutrons in boron neutron capture therapy system (BNCT) as well as geometrical and physical optimization of BNCT system elements. Our choice is BNCT system with linear accelerator. BNCT track includes ion injector, RFQ, DTL, neutron-producing target and neutron moderator which provides an exit (last collimator) flux of epithermal neutrons satisfied to International Atomic Energy Agency (IAEA) requirements. The following software tools IBSimu, LIDOS, COMSOL Multiphysics and PHITS were used for modelling BNCT system.

We present a new analysis of the sensitivity of a water Cherenkov-based neutron multiplicity counter for nondestructive assay of trace quantities of 240Pu. The multiplicity counter [water-based neutron detector (WaND)] contains 1.0 m3 of water doped with 0.2% gadolinium in the form of a gadolinium salt (0.4% GdCl3). It can be used for testing the presence of trace quantities of 240Pu within a sample of unknown material by observing the correlated timing behavior of neutron capture candidates in the detector. The new analysis takes advantage of the fact that the detector is comprised almost entirely of a homogeneous medium, which permits the use of a simple model to reproduce the observed neutron capture timing behavior. The results of this analysis indicate that the detector has an absolute neutron detection efficiency of 23.4 ± 1.1% and is sensitive to a 240Pu mass as small as 2.3 mg (at $1\sigma $ ) after a 1-h data acquisition.

In order to validate the neutron absorption cross sections in the JENDL-4.0 nuclear data library, critical analysis was performed using a continuous-energy Monte Carlo calculation code for the ligh...

Metal-organic frameworks (MOFs) are known for their versatility in terms of their crystalline structure, porosity, resistance to temperature, radiation damage, and luminescence among others. Gadolinium (Gd) is one of the elements with the highest reported cross-section for low energy neutron capture, producing internal conversion electrons and γ rays as a result of the neutron absorption. The development of Gd-BTC films (BTC=1,3,5-benzenetricarboxylate) is shown that were deposited on Si and Al substrates by airbrushing, and characterized by profilometry, Raman, EDX and X-ray diffraction. Radiation damage, thermal decomposition and neutron absorption of these films were studied as well. Gd-BTC films were attached to CMOS devices (Complementary Metal-Oxide-Semiconductor), which are sensible to the internal conversion electrons, in order to build a neutron detector. The devices Gd-BTC/CMOS could selectively detect neutrons in the presence of γ rays with a thermal neutron detection efficiency of 3.3±0.1 %, a signal to noise ratio of 6 : 1, and were suitable to obtain images.

A vacuum insulated tandem accelerator was used to study the effect of blistering on the neutron yield under 2-MeV proton bombardment of lithium target. The target is a thin lithium layer evaporated onto an efficiently cooled copper substrate. Targets with lithium thickness from 1 to 84 µm were irradiated by protons up to fluence of 6.3 1020 cm−2 which was significantly greater than the blistering threshold. The state of the targets surface was observed using long-distance microscope, video camera, infrared camera. The neutron dose was measured by dosimeters, the neutron flux density was measured by neutron detector. After irradiation, the targets were analyzed on Raman spectrometer, single crystal diffractometer, electron microscope, scanning profilometer, scanning electron microscope, atomic emission spectrometer. The article describes the experiment, presents the results obtained and notes their significance in the enhancement of a target for the neutron source used in boron neutron capture therapy.

In this article, we consider some mechanisms of the formation of a nanometer-thick surface layer enriched with 14C isotope. Main channel of 14C surface accumulation is believed to be the neutron capture reaction with 14N atoms of the cooling gas mixture during operation of uranium-graphite reactors, in particular, a high-power channel-type reactor (RBMK-type reactor). For the “dry” collection of thin layers enriched in 14C isotope from the irradiated graphite surface of graphite-type nuclear reactor and further compact burial, we propose argon plasma discharge technology based on the special type of a microdischarge at a high pressure, up to atmospheric pressure. In addition, there are some important technical applications, such as brachytherapy medicine or new beta-voltaic batteries, which require the deposition of thin layers of beta-active isotopes (e.g. 14C) with nanoscale precision to form a controlled output energy spectrum of secondary electrons. The proposed technological scheme can potentially be used both for graphite deactivation in the irradiated reactor during decommissioning of uranium-graphite reactors, and at the same time for fabrication of highly concentrated 14C nanosized coatings for use in radionuclide medicine and beta-voltaic batteries.

Введение. Бор-нейтронозахватная терапия (БНЗТ) является перспективной экспериментальной методикой лечения онкологических заболеваний. По данным клинических исследований пациентов с глиобластомой и меланомой, леченных БНЗТ на ядерных реакторах, отмечены рост медианы выживаемости и улучшение качества жизни. Для получения эпитепловых нейтронов ведется разработка новых источников на основе ускорителей заряженных частиц. Один из проектов был реализован в Институте ядерной физики им. Г.И. Будкера СО РАН, достигнутые параметры пучка позволяют проводить доклинические исследования. Цель работы - выявление на клеточных линиях глиомы и меланомы зависимости эффективности БНЗТ от концентрации бора при использовании пучка, генерируемого на источнике эпитепловых нейтронов ускорительного типа Института ядерной физики им. Г.И. Будкера СО РАН и оценка перспектив использования этого источника эпитепловых нейтронов для дальнейших клинических исследований. Методика. Клеточные линии U251 (глиома) и SK-Mel28 (меланома) опухолей человека инкубировали с добавлением в ростовую среду различных концентраций бора, используя препарат борфенилаланин, в течение 24 ч, затем облучали потоком нейтронов. Измерение концентрации изотопа бора 10В в опухолевых клетках проводили на атомно-эмиссионном спектрометре ICPE-9820 (Shimadzu, Япония). Клоногенный тест использовали для оценки влияния бор-нейтронозахватной терапии на клетки глиомы и меланомы. Результаты. Анализ данных БНЗТ показал, что колониеобразующие свойства облученных клеток глиомы и меланомы уменьшались с повышением концентрации бора. Так, по мере накопления бора линией SK-Mel28 увеличивается количество погибших клеток после облучения, а концентрация 10В 25 мкг/мл обеспечивает летальную дозу для 100% клеток (LD100). Глиальная линия накапливает бор менее интенсивно и гибель 100% клеток происходит при концентрации 10В 50 мкг/мл. В образцах, облученных без бора, в сравнении с контролем также наблюдалось снижение выживаемости клеток из-за присутствия быстрых нейтронов и гамма-излучения. Заключение. Данные экспериментов in vitro доказывают эффективность действия бор-нейтронозахватной терапии на клетки глиомы и меланомы при использовании источника эпитепловых нейтронов ускорительного типа ИЯФ СО РАН и борфенилаланина как агента доставки бора с концентрацией 10В 6,25-50 мкг/мл, а также перспективность использования данного метода в лечении таких опухолей, как глиома и меланома. Boron neutron capture therapy (BNCT) is a promising experimental method for the treatment of oncological diseases. According to results of clinical trials, patients with glioblastoma and melanoma treated with BNCT at nuclear reactors showed an increase in median overall survival and an improvement in quality of life. To obtain epithermal neutrons, new sources based on charged particle accelerators are being developed. One of the projects was implemented at the G.I. Budker Institute of Nuclear Physics, and the obtained beam parameters allowed conducting preclinical experiments. The aims were to identify the dependence of the effectiveness of BNCT in glioma and melanoma cell lines on boron concentrations using a beam generated at the accelerator based epithermal neutron source in the G.I. Budker Institute of Nuclear Physics and to evaluate prospects for using this epithermal neutron source for further clinical research. Methods. The U251 glioma cell line and the SK-Mel28 melanoma cell line were incubated with various concentrations of boronophenylalanine added to the growth medium for 24 hours and then irradiated with a neutron flux. The 10B accumulation in tumor cells was measured with an ICPE-9820 atomic emission spectrometer (Shimadzu, Japan). The effect of BNCT on glioma and melanoma cells was evaluated by the colony forming assay. Results. Analysis of the BNCT experimental data showed that the colony-forming capabilities of irradiated glioma and melanoma cells decreased in proportion to the increase in boron concentration. Thus, increasing accumulation of boron by SK-Mel 28 cells provided a greater number of dead cells with irradiation at a concentration of 10B of 25 µg/ml being a lethal dose for 100% of the cells (LD100). The glial cell line accumulated boron less intensively; death of 100% of cells occurred at a 10B concentration of 50 µg/ml. In samples irradiated without boron, the number of colonies was also decreased compared to the control due to the presence of fast neutrons and gamma-radiation components. All differences between the control and the experiment were statistically significant (p

Neutron yields from 9Be(p,xn) reactions with a 2-cm thick beryllium target bombarded by proton beams of 5, 6, 7, 8, 9, and 10 MeV were investigated. Neutron beam characteristics through a pilot design of beam shaping assembly were calculated by using MCNP6, PHITS, and GEANT4. The neutron yield with a 10 MeV beam by MCNP6 was 7.7 times larger than values by the other codes, but close to the experimental data. The neutron spectrum and directionality were different among the codes. These differences could stem from different cross-section libraries and models used in the codes. The epithermal flux at the beam irradiation port by MCNP6 was 1.4 × 109 cm−2 s−1 for a proton current of 8 mA hitting the target. The ratio of thermal and epithermal flux was less than 0.01 and the forward directionality was 0.78. However, we suggest a new criterion regarding a ratio of fast and epithermal flux.

The development of new accelerators has given a new impetus to the development of new drugs and treatment technologies using boron neutron capture therapy (BNCT). We analyzed the current status and future directions of BNCT for cancer treatment, as well as the main issues related to its introduction. This review highlights the principles of BNCT and the key milestones in its development: new boron delivery drugs and different types of charged particle accelerators are described; several important aspects of BNCT implementation are discussed. BCNT could be used alone or in combination with chemotherapy and radiotherapy, and it is evaluated in light of the outlined issues. For the speedy implementation of BCNT in medical practice, it is necessary to develop more selective boron delivery agents and to generate an epithermal neutron beam with definite characteristics. Pharmacological companies and research laboratories should have access to accelerators for large‐scale screening of new, more specific boron delivery agents.

The objectives of this study were to determine the effect of boron concentration on total dose rate for lung cancer treatment, and to determine the effect of boron concentration on the length of irradiation time for lung cancer treatment. This study was computer simulation-based using the Particle and Heavy Ion Transport code System (PHITS) by defining the geometry and components of lung cancer and the surrounding organism as the object being studied and the source of radiation used. The type of phantom used was the ORNL of an adult Asian male. The neutron source used was Kartini Reactor. The independent variable was the boron concentration of 30, 40, 50, 60, and 70 ?g/g cancer tissue and the dependent variables were the dose rate and the irradiation time. The results of this study indicated that the larger the amount of boron concentration that was injected, the higher the rate of total dose the organ received, where the total dose rate for each variation of boron concentration were 1.34 × 10-3 Gy/s, 1.71 × 10-3 Gy/s, 2.07 × 10-3 Gy/s, 2.42 × 10-3 Gy/s, and 2.78 × 10-3 Gy/s, and the larger the amount of boron concentration that was injected, the faster the irradiation time for the treatment of lung cancer was, where the irradiation time required for each variation of boron concentration was 37294 s, 29240 s, 24180 s, 20633 s, and 17996 s.

Neutron capture therapy (NCT) is a promising method of curing cancer, which uses stable isotopes with large thermal neutron capture cross section value (a) to provide selective damage of a tumor. Boron isotope 10 B (a = 3880 barn) is the most know and most widely used in NCT isotope. Gadolinium isotope 157Gd has even larger thermal neutron capture cross section value ( σ = 254 000 barn) than 10 B, but secondary radiation emitted by this isotope as the results of neutron capture nuclear reaction is absorbed by tumor tissues less effectively than for 10 B. The purpose of this research was to study gadolinium neutron capture therapy efficacy in curing spontaneous tumors. 13 dogs diagnosed with oral cavity spontaneous melanoma were studied. MRI contrast drug Dipentast® was used as a gadolinium containing substance. The drug was injected directly into the tumor immediately before neutron irradiation. The administered dose of the drug was 10 mg of gadolinium per 1 cm 3 of tumor. The irradiation was made with thermal neutron beam with neutron flux 7x10 8 n/cm 2 s and 3-6 cm diameter. The duration of irradiation was 70 minutes. As the results of the therapy complete tumor regression was achieved in 46 % of animals. Recurrence free period was 106.0±7.5 days for 66.7 % of dogs with complete tumor regression and more than 150 days for 16.7 %.

The measurements of Cs isotopic ratios by TIMS were performed for the sample analysis used to evaluation of the nuclear data of 135Cs. To obtain a high intensity and stable ion beam, the effects of additive agents on the ionization of Cs were examined. The effect of silicotungstic acid on the ionization of Cs was the largest among the additive agents discussed in this study, while this also showed the largest isobaric interference of polyatomic ions. After examining of the analytical conditions, such as the interference effect due to Ba, the sample analysis of two radioactive Cs samples were conducted.

A Prompt Gamma-ray Neutron Activation Analysis (PGNAA) facility was set up using a thermal neutron beam at Dhruva research reactor. It was utilized for non-destructive quantification of total boron in refractory neutron absorbers and 10B atom% in B4C ceramics having natural and enriched 10B composition by measuring the 478 keV prompt gamma-ray from 10B(n,αγ)*7Li. Self-shielding correction was carried out for higher boron concentration samples using chlorine as an internal standard. As a part of quality assurance, the results of PGNAA were compared with those obtained by in situ current normalized Particle Induced Gamma-ray Emission (PIGE) method.

The Reactor Experiment for Neutrino Oscillation (RENO) experiment has been taking data using two identical liquid scintillator detectors of 44.5 tons since August 2011. The experiment has observed the disappearance of reactor neutrinos in their interactions with free protons, followed by neutron capture on hydrogen. Based on 1500 live days of data taken with 16.8 GW$_{th}$ reactors at the Hanbit Nuclear Power Plant in Korea, the near (far) detector observes 567690 (90747) electron antineutrino candidate events with a delayed neutron capture on hydrogen. This provides an independent measurement of $\theta_{13}$ and a consistency check on the validity of the result from n-Gd data. Furthermore, it provides an important cross-check on the systematic uncertainties of the n-Gd measurement. Based on a rate-only analysis, we obtain sin$^{2}$2$\theta _{13}$= 0.087 $\pm$ 0.008 (stat.) $\pm$ 0.014 (syst.)., Comment: 26 pages, 19 figures, 6 tables

The Graphite Isotope Ratio Method (GIRM) can verify non-proliferation of nuclear weapon by estimating the total plutonium production in a graphite-moderated reactor. Using the reactor, plutonium is generated and accumulated through the 238U neutron capture reaction, and impurities in the graphite are converted to nuclides due to the nuclear reaction. Therefore, the amount of plutonium production and concentration of the impurities are correlated. However, the plutonium production cannot be predicted using only the absolute concentration of the impurities. It can only be predicted when the initial concentration of the impurities is obtained because the concentration, at a certain time, depends on it. Nevertheless, the ratios of the isotopes in an element are known regardless of the impurity of an element in the graphite moderator. Thus, the correlation between the isotope ratio and amount of plutonium produced helps predict plutonium production in a graphite-moderated reactor. Boron, Lithium, Chlorine, Titanium, and Uranium are known as indicator elements in the GIRM. To assess whether the correlation between the indicator isotope and amount of plutonium produced is independent of the initial concentration of the impurities, four different impurity compositions of graphite were used. 10B/11B, 36Cl/35Cl, 48Ti/49Ti, and 235U/238U had a consistent correlation with the cumulative plutonium production, regardless of the initial impurity concentration of the graphite, because these isotopes were not generated through the nuclear reaction of other elements. On the other hand, the correlation between 6Li/7Li and plutonium production depended on the initial concentration of the impurities in graphite. Although 7Li can be produced through the neutron capture reaction of 6Li, the (n, α) reaction of 10B was the major source of 7Li. Therefore, the initial concentration of 10B affected the production of 7Li, making Li unsuitable as an indicator element for the GIRM.

Boron carbide enriched with 10B isotope (10B4C) was synthesized by simple and low cost solvothermal method. Structural, morphological and optical analysis has been done. Hexagonal phase of the synthesized material show emission in visible region and makes it a promising material for cancer diagnosis. Cytotoxicity analysis has been done to analyze its suitability for biomedical applications. Boron neutron capture therapy (BNCT) has been performed using thermal neutron source in comparison to clinically studied compound on tumor cell lines (HeLa and U-87MG).

A method for producing elemental boron nanoparticles with a size of less than 100 nm by ultrasonic dispersion in a liquid medium and subsequent cascade fractionation is described. The resulting boron nanoparticles were used as a target for boron neutron capture therapy (BNCT). According to the results of an experimental preclinical study of BNCT with the synthesized boron nanoparticles, neutron irradiation for 1 h of T98G human glioma cells pre-incubated in a medium with boron nanoparticles (10, 20, and 40 ppm in terms of boron-10 isotope) leads to a significant suppression of cell viability.

The determination of boron in animal organ tissues using inductively coupled plasma atomic emission spectroscopy (ICP AES) has been optimized for analytical support of boron neutron capture therapy of cancerous tumors. The proposed technique is universal and rapid. The methodology includes: preliminary acid decomposition at elevated temperatures and pressure (if necessary), determination of boron by ICP AES in the obtained solutions using reference samples based on single-element solutions. The method is verified by spike experiment and varying the weight-samples. The ICP AES technique was used to evaluate the accumulation of boronophenylalanine and borocaptate in mice organs. Biodistribution of 10B in the case of intravenous administration of the drug to SCID mice with SPF status using the human glioblastoma cell line U87 was investigated.