Nuclear Transmutation Reactions Research Articles

Structural and mechanical responses of (ZrTiNbTa)C4 and ZrC ceramics under energetic He-ions irradiation

High entropy ceramics are potential structural materials for advanced reactor concepts where numerous helium atoms would be produced due to the (n, α) nuclear transmutation reaction. However, the irradiation behaviors of high entropy ceramics are not well understood until now. In present work, the responses of high entropy (ZrTiNbTa)C4 and its binary constituent ZrC ceramics to energetic He-ions irradiation have been studied. X-ray diffraction analysis showed that He-ions irradiation resulted in peak shift and broadening of diffraction peaks in both (ZrTiNbTa)C4 and ZrC, which denotes lattice expansion and structural damages induced by the irradiation. Transmission electron microscope observation revealed that spherical helium bubbles distribute uniformly in the grain interiors of (ZrTiNbTa)C4 while “string-like” bubbles with a preferred orientation are observed in ZrC grains. Nanoindentation characterization gives that the irradiation induced hardening of (ZrTiNbTa)C4 is less definite than that of ZrC. The irradiation mechanisms of high entropy ceramics have been discussed.

Crater formation and deuterium production in laser irradiation of polymers with implanted nano-antennas.

Recent validation experiments on laser irradiation of polymer foils with and without implanted golden nanoparticles are discussed. First we analyze characteristics of craters, formed in the target after its interaction with the laser beam. Preliminary experimental results show significant production of deuterons when both the energy of laser pulse and concentration of nanoparticles are high enough. We consider the deuteron production via the nuclear transmutation reactions p+C→d+X where protons are accelerated by the Coulomb field generated in the target plasma. We argue that maximal proton energy can be above threshold values for these reactions and the deuteron yield may noticeably increase due to presence of nanoparticles.

Tl-Doped CsI/⁶LiBr Scintillator for Thermal Neutron Detection With Ultrahigh Light Yield

In this study, a novel thermal neutron scintillator of Tl:CsI/LiBr was developed. The eutectics were fabricated at the various growth rate and investigated their scintillation properties. As a material design guideline, Tl:CsI, which has an excellent α/γ ratio, was selected as the scintillator phase to realize high light yield at the energy of α-rays and tritons generated by the nuclear transmutation reaction with <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> Li, and LiBr, which has a refractive index close to that of CsI, was selected as the neutron capture phase. Radioluminescence measurement under X-ray irradiation was also performed to obtain the emission spectrum of the eutectics. The light yield and decay time for thermal neutron were measured using <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">252</sup> Cf and were much higher than those of conventional scintillators for thermal neutron. Furthermore, fabricated eutectic can have the higher sensitivity to thermal neutron due to the high <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> Li concentration compared to conventional single crystal scintillators. Therefore, we have succeeded in developing a promising scintillator material.

1135P - Updated results of a phase II study evaluating accelerator-based boron neutron capture therapy (AB-BNCT) with borofalan(10B) (SPM-011) in recurrent squamous cell carcinoma (R-SCC-HN) and recurrent and locally advanced non-SCC (R/LA-nSCC-HN) of the head and neck

BackgroundBNCT is a unique cancer treatment technique in which tumor cells are irradiated from the inside with heavy particles produced by 10B(n,α)7Li nuclear transmutation reaction of boron atom and neutron. A next-generation AB-BNCT system that does not require a nuclear reactor has been developed, and it has become possible to perform BNCT in urban hospitals along with stable supply of borofalan (10B) supported by high 10B concentration technology. MethodsIn this world-first, open-label phase II trial of AB-BNCT, patients (pts) with previously irradiated, platinum-resistant R-SCC-HN or with R/LA-nSCC-HN were administered with borofalan(10B) at 200mg/kg/h intravenously for 2hours, followed by neutron irradiation with continuous infusion at 100mg/kg/h. The irradiated dose for tumor was determined passively as a mucosal maximum dose was given 12Gy-Eq. Primary endpoint was objective response rate (ORR) by central review. Updated efficacy and safety analysis are presented here (data cut off: 5 April 2019). ResultsEight R-SCC-HN and thirteen R/LA-nSCC-HN pts were enrolled. All R-SCC-HN pts had prior radiotherapy with a dose of 65.5Gy (range, 59.4–76.0). The tumor minimum dose was 31.0Gy-Eq (range, 16.1–42.6). ORR for all pts were 71.4%, and CR/PR were 50.0%/25.0% in R-SCC-HN and 7.7%/61.5% in R/LA-nSCC-HN. With a median follow up of 21.3 months (range 9.2–30.6), 1-year PFS by investigator review were 70.6%. Other ecacy data are shown in the table. For adverse event, nausea (81%), dysgeusia (71%), acute parotitis (67%) were observed frequently.Table: 1135PTable: 1135PAll (N=21)R-SCC-HN (N=8)R/LA-nSCC-HN (N=13)Overall response rate, n (%) (95% CI)15 (71.4) (47.8–88.8)6 (75) (34.9–96.8)9 (69.2) (38.6–90.9)Disease control rate, n (%) (95% CI)20 (95.2) (76.2–99.9)7 (87.5) (47.3–99.7)13 (100) (79.4–100)Median progression-free survival, monthsNR10.4NR1-y / 2-y progression-free survival rate, %70.6 / 65.530.0 / 15.092.3 / 92.31-y / 2-y overall survival rate, %94.7 / 85.383.3 / 55.6100 / 100NR, Not reached. ConclusionsThese data suggest that AB-BNCT with borofalan(10B) emerges as a promising treatment option for pts with R –SCC- HN or R/LA-nSCC-HN with no other treatment option. Clinical trial identificationJapicCTI-194640. Legal entity responsible for the studySumitomo Heavy Industries, Ltd, Stella Pharma Corporation. FundingFukushima prefectural subsidy for development and testing of global cutting-edge medical devices. DisclosureK. Hirose: Research grant / Funding (self), Travel / Accommodation / Expenses: Sumitomo Heavy Industries, Ltd; Travel / Accommodation / Expenses: Stella Pharma Corporation. K. Ono: Advisory / Consultancy: Stella Pharma Corporation; Advisory / Consultancy: Sumitomo Heavy Industries, Ltd. Y. Takai: Travel / Accommodation / Expenses: Stella Pharma Corporation; Travel / Accommodation / Expenses: Sumitomo Heavy Industries, Ltd. All other authors have declared no conflicts of interest.

Simulation for thick-target yields of transmutation reactions on radioactive targets, based on inverse kinematics

To dispose of long-lived fission products (LLFP) ejected from nuclear reactor plants is one of the most important tasks on nuclear physics and engineering. The ex- periments with the radiative target are limited, due to the high radioactivity and chemical property of the target. In consequence, the nuclear reaction data for LLFP are insufficient. In this work, we propose a feasible method to obtain the data for radiative targets using inverse kinematics and simulate specific systems to evaluate the thick-target yields of the nuclear transmutation reactions for LLFP.

Transmutation Reactions Induced by Deuterium Permeation through Nano-Structured Palladium Multilayer Thin Film

Low energy nuclear transmutation reactions have been observed in nano-structured Pd multilayer thin film which is composed of Pd and CaO thin film and Pd substrate, induced by D 2 gas permeation 1-5 . Up to now we have observed transmutation reactions of Cs into Pr, Ba into Sm and W into Pt. Replication experiments have been successfully performed by some researchers and Toyota R&D Center published almost complete replication experiments 8 on the transmutation of Cs into Pr last year. This new phenomenon would be used as an innovative nuclear transmutation method for radioactive waste 9-11 or a new energy source if we could solve many problems for commercialization.

Primary retention following nuclear recoil in β-decay: Proposed synthesis of a metastable rare gas oxide (38ArO4) from (38ClO4−) and the evolution of chemical bonding over the nuclear transmutation reaction path

Argon tetroxide (ArO4) is the last member of the N=50 e– isoelectronic and isosteric series of ions: SiO44−, PO43−, SO42−, and ClO4−. A high level computational study demonstrated that while ArO4 is kinetically stable it has a considerable positive enthalpy of formation (of ~298kcal/mol) (Lindh et al., 1999. J. Phys. Chem. A 103, pp. 8295–8302) confirming earlier predictions by Pyykkö (1990. Phys. Scr. 33, pp. 52–53). ArO4 can be expected to be difficult to synthesize by traditional chemistry due to its metastability and has not yet been synthesized at the time of writing. A computational investigation of the changes in the chemical bonding of chlorate (ClO4−) when the central chlorine atom undergoes a nuclear transmutation from the unstable artificial chlorine isotope 38Cl to the stable rare argon isotope 38Ar through β-decay, hence potentially leading to the formation of ArO4, is reported. A mathematical model is presented that allows for the prediction of yields following the recoil of a nucleus upon ejecting a β-electron. It is demonstrated that below a critical angle between the ejected β-electron and that of the accompanying antineutrino their respective linear momentums can cancel to such an extent as imparting a recoil to the daughter atom insufficient for breaking the Ar–O bond. As a result, a primary retention yield of ~1% of ArO4 is predicted following the nuclear disintegration. The study is conducted at the quadratic configuration interaction with single and double excitations [QCISD/6−311+G(3df)] level of theory followed by an analysis of the electron density by the quantum theory of atoms in molecules (QTAIM). Crossed potential energy surfaces (PES) were used to construct a PES from the metastable ArO4 ground singlet state to the Ar–O bond dissociation product ArO3+O(3P) from which the predicted barrier to dissociation is ca. 22kcal/mol and the exothermic reaction energy is ca. 28kcal/mol [(U)MP2/6–311+G(d)].

Carbon‐11 and fluorine‐18 chemistry devoted to molecular probes for imaging the brain with positron emission tomography

Exploration of the living human brain in real-time and in a noninvasive way was for centuries only a dream, made, however, possible today with the remarkable development during the four last decades of powerful molecular imaging techniques, and especially positron emission tomography (PET). Molecular PET imaging relies, from a chemical point of view, on the use and preparation of a positron-emitting radiolabelled probe or radiotracer, notably compounds incorporating one of two short-lived radionuclides fluorine-18 (T1/2 : 109.8 min) and carbon-11 (T1/2 : 20.38 min). The growing availability and interest for the radiohalogen fluorine-18 in radiopharmaceutical chemistry undoubtedly results from its convenient half-life and the successful use in clinical oncology of 2-[(18) F]fluoro-2-deoxy-d-glucose ([(18) F]FDG). The special interest of carbon-11 is not only that carbon is present in virtually all biomolecules and drugs allowing therefore for isotopic labelling of their chemical structures but also that a given molecule could be radiolabelled at different functions or sites, permitting to explore (or to take advantage of) in vivo metabolic pathways. PET chemistry includes production of these short-lived radioactive isotopes via nuclear transmutation reactions using a cyclotron, and is directed towards the development of rapid synthetic methods, at the trace level, for the introduction of these nuclides into a molecule, as well as the use of fast purification, analysis and formulation techniques. PET chemistry is the driving force in molecular PET imaging, and this special issue of the Journal of Labelled Compounds and Radiopharmaceuticals, which is strongly chemistry and radiochemistry-oriented, aims at illustrating, be it in part only, the state-of-the-art arsenal of reactions currently available and its potential for the research and development of specific molecular probes labelled with the positron emitters carbon-11 and fluorine-18, with optimal imaging properties for PET exploration of the brain.

New method for detection of Li inside He bubbles formed in B10-alloyed steel after neutron irradiation

Electron energy loss spectroscopy (EELS) was used to detect and study the spatial distribution on the nanoscale of He and Li in boron-alloyed steel after neutron irradiation. Li and He are the products of the 10B(n, α)7Li nuclear transmutation reaction and knowledge of their distribution is important to understand their influence on mechanical properties. Here, a new method is presented for the direct detection of Li in Fe, which is based on the analysis of the plasmon structure in EELS spectra. Li drops or particles in He bubbles show pronounced Li plasmon line at 10eV which can be extracted from the Fe/Cr plasmon. The Gaussian or linear interpolation of the Fe/Cr plasmon and its subtraction allows for the calculation of Li and He two-dimensional maps and the study their spatial distribution. The analysis of Li plasmon fine structure allows imaging surface effects in the Li drops.

Abnormal Heat by Thermal Changing in a D-Pd Gas-Loading System

In order to explore the condensed phase whether may promote abnormal heating phenomenon and nuclear reactions occur, as well as how to construct and characterization of condensed phase structure filled with deuterium and the use of exogenous trigger transient change. Some deuterium atoms were charged into metal palladium lattice and reached a certain ratio in a D-Pd gas-solid system under the pressure of PD26J heat energy were released in 8 hours, when loading ratio of deuterium x was 0.12, current 8A, pressure 9×104Pa. Improvement of experiment, that excess heat power 41W and 79.58MJ heat energy, which was corresponding to 1.8×104eV for each palladium atom were released in 83 hours and 17 minutes, when current 7.25A, pressure 9×104Pa. An energy dispersive spectrometer (EDS) revealed that new surface topographical features with concentrations of unexpected elements Ag were detected, which implied that the excess heat might come from a nuclear transmutation reaction.

ЯдЕрныЕ реакции, технологИИ модИфИкацИИ И АнАлизА материалоВ

The features of the modification technologies of substances and materials by flows of ionizing radiation are considered. The latest technologies of radioactive waste utilization based on nuclear transmutation reactions are analyzed

An Excess Heat Phenomenon Triggered by Pressure in a H-Pd Gas-Loading System

Some hydrogen atoms were being charged into metal palladium lattice and reached a certain ratio in a H-Pd gas-loading system under the pressure of PH2&lt;1atm. The relationship between loading ratio, pressure and excess heat were studied at different reaction conditions. In one of the experiments the palladium wire was broken with a huge excess heat. The calculation results showed that about 2.2×104 Joules excess energy were released in that abnormal process, which was corresponding to 2.5×102eV for each palladium atom. Analysis on the surface of the melted broken section of palladium wire sample before and after the abnormal process with a scanning electron microscopy (SEM) and an energy dispersive spectrometer (EDS) revealed that new surface topographical features with concentrations of unexpected elements (Ag and Ca) were detected, which implied that the excess heat might come from a nuclear transmutation reaction

Neutron activation analysis for investigating purity grade of copper, nickel and palladium thin films used in cold fusion experiments

In the last decades some scientific papers have been published on the study of nuclear transmutation reactions in condensed matter, in which the formation of new nuclear products was investigated. In this contest, a specific research activity based on electrolysis process has been developed at ENEA: each step has been analyzed and deeply investigated by Instrumental Neutron Activation Analysis (INAA). The materials such as electrolysis equipment, electrolytic solutions, electrodes, etc. were preliminarily analyzed by INAA for identifying and reducing all the pollution sources. Several experiments were performed using films of copper, nickel and palladium as electrodes. At the end of each test, all the materials and the electrolytic solutions used and the blank as well were analyzed by INAA for checking and measuring the presence of nuclei originating from nuclear transmutations. INAA is in fact able to determine element content at a very low level, where other analytical techniques cannot reach with such precision and accuracy. The results obtained are strongly random demonstrating a phenomenon of apparent enrichment rather than the occurrence of transmutation phenomena in the condensed matter during the electrolysis.

First-principles study of hydrogen behavior in V–Cr–Ti alloys

V–Cr–Ti alloys are considered as one of the most promising candidate structural materials for fusion reactor. Hydrogen impurities originated from bombarding with reaction plasma as well as various nuclear transmutation reactions have a considerable influence on the performance and stability of V–Cr–Ti alloys. To understand the microscopic mechanism, we have simulated the behaviors of H atoms inside the pure vanadium solid as well as V-based alloys (V–4Cr–4Ti and V–5Cr–5Ti) using first-principles approach. The binding energies or absorption energies for H atom inside different interstitial sites were compared to determine the optimal trapping sites. Interaction between two interstitial H atoms was calculated and fit into a screened Coulomb potential. H atom prefers to diffuse along path between two nearest interstitial sites with low energy barriers of 0.20–0.34eV.

Material degradation under DEMO relevant neutron fluences

In fusion power reactors, the plasma facing and breeding-blanket components will suffer intense irradiation by 14 MeV neutrons. These high-energy fusion neutrons will produce atomic displacement cascades and nuclear transmutation reactions inside the irradiated materials, and these will result in important radiation damage and effects. In the present paper, typical examples of radiation damage and effects on candidate materials for plasma facing components in fusion power reactors are presented and discussed.

Nucleation path of helium bubbles in metals during irradiation

A thermodynamic formalization is developed for description of the nucleation and growth of helium bubbles in metals during irradiation. The proposed formalization is available for evaluating both microstructural changes in fusion first wall materials where helium is produced by (n, α) nuclear transmutation reactions, and those in fusion diverter materials where helium particles with low energy are directly implanted. The calculated nucleation barrier is significantly reduced by the presence of helium, showing that a helium bubble with an appropriate number of helium atoms depending on bubble size can nucleate without any large nucleation barriers, even at a condition where an empty void has very large nucleation barriers without helium. With the proposed thermodynamic formalization, the nucleation and growth process of helium bubbles in iron during irradiation is simulated by the kinetic Monte Carlo (KMC) technique. It shows the nucleation path of a helium bubble on the (N He, N V) space as functions of temperatures and the concentration of helium in the matrix, where N He and N V are the numbers of helium atoms and vacancies contained in the helium bubble, respectively. Bubble growth rates depend on the nucleation path and suggest that two different mechanisms operate for bubble growth: one is controlled by vacancy diffusion and the other is controlled by interstitial helium diffusion.

Electrical characterization of B10 doped diamond irradiated with low thermal neutron fluence

A sample of B10 isotope doped diamond was neutron irradiated to a thermal fluence of 1.3×1019 neutron cm−2. The diamond sample was cooled continuously during irradiation in a nuclear reactor. Li7 is formed by nuclear transmutation reaction from B10. Characterization for electrical conductance in the temperature range of 160 K&amp;lt;T&amp;lt;600 K was performed on an unirradiated B10 doped sample and the B10 doped and irradiated sample. The unirradiated diamond sample showed p-type conductance at higher temperature (T&amp;gt;200 K) and p-type surface conductance at lower temperature (T&amp;lt;200 K). The irradiated sample showed decreasing conductance below 230 K and increasing conductance above 230 K with increasing temperature. Furthermore, the conductance showed a decrease above 400 K followed by an increase above 500 K. The observed behavior below 400 K with increase in temperature is interpreted in terms of compensation of surface p-type carriers by n-type bulk carriers generated from Li7 that is formed by nuclear transmutation reaction from B10 atoms. Also, compensation of n-type carriers from Li7 by p-type carriers from B10 is used to interpret the conductance above 400 K. A low concentration of radiation induced defects, absence of defect complexes, and the low activation energy of n-type Li7 are thought responsible for the observed variation of conductance in the irradiated diamond. The present results illustrate that neutron transmutation from B10 doped diamond is a useful method to achieve n-type conductivity in diamond.

In-situ irradiation test of mica substrate bolometer at the JMTR reactor for the ITER diagnostics

Irradiation tests of a mica substrate bolometer were carried out at the Japan Materials Testing Reactor up to the fast neutron fluence of 0.1 dpa. A performance of the bolometer was investigated during the irradiation. Significant increase of the meander resistance from 275 to 446 Ω was observed in the fast neutron fluence of 0.06 dpa. In the post-irradiation examination (PIE), it was confirmed that the gold meander contained 46% mercury which was produced by the nuclear transmutation reaction of 197Au(n, γ) 198Au→ 198Hg+β −. The bolometer sensitivity was measured by the change of the meander resistance for the input power. The sensitivity decreased slightly at constant reactor power. There was not significant change in the bolometer response time. During the cool down phase of the first cycle all connections went open circuit. Some recovered on start-up of the second cycle, however, all connections went open circuit again near the end of the second cycle. They were not recovered any more at the third cycle. Breaks of the gold meander were observed in the PIE. The use of gold meanders might be problematic in ITER.

Effect of helium to dpa ratio on fatigue behavior of austenitic stainless steel irradiated to 2 dpa

The effect of helium due to nuclear transmutation reactions during neutron irradiation on low cycle fatigue life of type 304 stainless steel was investigated. The specimens were irradiated in spectrally tailored capsules in the Japan Materials Testing Reactor (JMTR) at a temperature of 823 K to a neutron fluence of approximately 1×1025n/m2(E>1MeV) and helium levels of 0.8, 2.5 and 8.1 appm. The low cycle fatigue tests were performed in total axial strain ranges of 0.8–1.6% at 823 K. A laser extensometer was used for controlling the axial strain of a specimen under cyclic testing. The difference between unirradiated and irradiated specimens is quite clear and appears to be a reduction by a factor of 2–5 in fatigue life. The helium concentration of the specimen is not the main factor to shorten fatigue life in the present experimental condition.

Transmutation in a Gold-Light Water Electrolysis System

Mercury, krypton, nickel, and iron with anomalous isotopic compositions were found to be produced on or in gold electrons during light water electrolysis. In addition, silicon and magnesium with anomalous isotopic compositions were also detected in the precipitates separated from the gold electrode electrolyzed at extremely high current densities. After the electrolysis, the surface of the electrode exhibited an extraordinary structure, i.e., a number of microcraters like volcanoes were developed. The structure of the outside wall of the craters was very much like that of the precipitates, and hexagonal crystallite layers in the inside wall of the craters suggested a partial recrystallization of the electrode material due to some intense heat evolution. The craters developed along the rim of the microcracks, microholes, and scraped edges of the electrode. These results suggest that some nuclear transmutation reactions occur during the electrolysis to produce these effects.