Nuclear fission serves as the most fundamental physics phenomenon underlying nuclear energy. It is quite a complex process of large-amplitude collective motion of finite quantal systems, which produces a huge energy of around 200 MeV/fission, and fission neutrons, which are used to sustain chain reactions, and over 1,000 kinds of fission products are produced. Understanding nuclear fission is...
$^{239}$Puの熱中性子核反応における核分裂収率を核反応モデル計算コードCCONE~[1] を用いて計算した。実験データと比較して検証した結果を本発表で行う。
これまでの核データにおける核分裂収率の評価は、主に独立核分裂収率と積算核分裂収率を基にして評価値が決められてきた。しかし核分裂収率は、全運動エネルギー(TKE)や即発中性子、崩壊熱など様々な観測量と関連する物理量であり、それらも考慮した評価値の決定が求められている。JENDL-5~[2]...
The purpose of this research is to design new radionuclides suitable for brachytherapy sources. Brachytherapy is one of the radiotherapy technique which sealed radionuclides in capsules are inserted into the body. Photons, electrons from a sealed source are usually used. Dose rate can be controlled using a variety of irradiation setup, such as placement and irradiation time to the patients. In...
Experimental nuclear reaction data are essential for understanding nuclear reaction phenomena, developing nuclear theories and models, and evaluating data for nuclear data libraries. Efficient data mining from the Experimental Nuclear Reaction Database (EXFOR)[1] has a potential for utilization of modern computational analysis techniques to find trends, shortcomings, and hidden patterns in the...
We have developed the radiation dose evaluation system for indoor environments named 3D-ADRES-Indoor, which is especially designed for two applications: the estimation of radioactive source distributions with the machine learning technique and the planning of measures against estimated radioactive sources [1,2]. 3D-ADRES-Indoor mainly uses Particle and Heavy Ion Transport code System (PHITS)...
The cross sections of neutron-induced charged-particle emission reactions such as (n,p) and (n,$\alpha$) for many nuclides have not been measured as well as those of the neutron capture reaction. In the present work, new measurement technique for neutron-induced charged-particle emission reactions were developed. The new method uses plastic scintillator added with sample material for...
In fluoroscopy, radiation shielding effectively reduces radiation exposure to medical staff [1]. However, it is still unclear how to understand where the scattered radiation comes from and how to properly use radiation shields. The purpose of this study is to clearly visualize the direction of scattered radiation to assist in the optimal use of radiation shields.
The Monte Carlo code PHITS...
In the case of accidents involving inhalation of radioactive materials, there is a need for rapid evaluation of the amount of transuranium (TRU) nuclides such as Pu ingested in the body by measurement from outside of the body. In the measurement, L X-rays, which have energies of 10 to 30 keV and are emitted by internal conversion electrons due to $\alpha$-decay, are used. In order to measure...
In Boron Neutron Capture Therapy (BNCT) facilities, concrete of the treatment room is activated by neutrons and dose rate in the treatment room is still high after the end of neutron irradiation. The concrete wall surrounding the room is thick enough to reduce dose rate outside the room to a safety level. The concrete in certain area of the wall is highly radioactive. Estimating the amount of...
Photonuclear reaction cross-section data are essential for electron accelerator shielding design and possibly nuclear transmutation. So far, photonuclear cross-sections of various target materials have been evaluated up to a photon energy of 200 MeV within the nuclear data libraries, such as JENDL-5 [1]. Almost all data in JENDL-5 have been evaluated based on the experimental reaction...
Shield tunneling methods are widely used to construct large underground tunnels. Although the methods are considered safe, subsidence accidents due to underground cavities created during tunnel excavation have occurred in recent years. To prevent such accidents, it is necessary to detect the cavities and take some measures. Various exploration methods such as ground-penetrating radar have been...
Fission product yields (FPY) is one of the most important nuclear data, which provide information necessary for applications like burn-up calculation in nuclear reactors, environmental assessment of radioactive waste disposal and evaluation for production of valuable isotopes such as $^{99}$Mo for medical imaging. Traditionally, major nuclear data libraries (such as JENDL, ENDF, JEFF, etc.)...
Nuclear data on carbon ion induced reactions in a wide range of energy are needed for purposes such as improvement radiation protection for space exploration and evaluation systems for secondary exposure on radiation therapy. However, it is reported that there is no measurement data on double differential cross sections of incident high energy $^{12}$C particles between 100 MeV/u and 500...
Neutron source term is required for shielding design of accelerator facilities. A Time-of-Flight (TOF) technique is applied to get the source term. When TOF cannot be utilized at accelerator facilities (e.g., Continuous Wave (CW) operation), an unfolding method is useful. However, the validity of unfolding is not completely understood.
One of the accelerator facilities where CW operation...
In equation of state of nuclear matter, constraints on parameters of the symmetry energy $S(\rho)$ are important for understanding of the nuclear many-body system which is related to various astrophysical phenomena. The symmetry energy is essential for the neutron matter ($\delta\sim 1$ where $\delta$ is degree of asymmetry), but it is less certain than the symmetric nuclear matter...
Fast neutron measurements are indispensable technique in the field of experimental nuclear physics and nuclear data measurement. In order to discriminate gamma rays generated by the production of fast neutrons, it is necessary to use a detector capable of discriminating between gamma rays and fast neutrons. As a typical detector for fast neutrons, organic liquid scintillators are widely used....
A variety of unstable nuclear beams with atomic numbers (Z) up to 92 can be produced by the projectile fragmentation and in-flight fission from high intensity U beams at RIBF. Recently, it was found that $^{234−238}$Np can be created by a proton pickup reaction on 1 GeV/nucleon $^{238}$U beam. Owing to the recent developments of the high-Z beams at BigRIPS, energy dependence of the proton...
The control of occupational exposure in fluoroscopy and interventional radiology is critical due to the risk of radiation exposure. Current dosimetry measurements have limitations, such as incomplete whole-body measurements and lack of real-time measurements. To improve radiation awareness, we have developed a system that displays 2D scattered radiation distribution and estimates the...
We have measured a small-angle neutron and X-ray scattering (SANS and SAXS) of cement paste to investigate a nanoscale structure of cement paste [1, 2]. Through the in-situ SAXS measurements of cement paste, in particular, we have focused on a fine nanostructure that emerged with time as a shoulder on the SAXS profiles at the high-q region of around 3 nm$^{-1}$. Based on a microstructure model...
The Intranuclear Cascade model have been improved for calculation of alpha incident reaction. The fragmentation reaction which is dominant in alpha incident reactions is calculated using the model that incident alpha particle is broke up according to the probability, which show cluster state in the alpha particle, and density distribution of targets. In addition, the direct knockout reaction...
Neutron activation analysis is used in a variety of many fields, such as geology, medicine, and archaeology. In the neutron activation method, a sample is irradiated with neutrons and activated via neutron-induced reactions. The elemental composition is determined from the radioactivity of the sample. In measurement of radioactivities, -rays are often detected with a germanium detector which...
Purpose: At energies above the ($\gamma$,n) threshold, photons can interact with the nuclei of high-Z materials, liberating fast neutrons. The aim of this study was to validate the Monte Carlo simulation with the PHITS code for the TrueBeam LINAC using mono-energy. Additionally, we examined the photon neutron dose surrounding the TrueBeam LINAC's head and investigated the influence of field...
BNCT is a radiation methodology utilizing the BNCR mechanism, depicted by $^{10}$B(n.$\alpha$)$^{7}$Li, to accurately target and eradicate tumor cells. The required $^{10}$B level for its therapeutic effect in BPA-BNCT is usually between 15-40 ppm. While this concentration serves as a standard for several boron derivatives, the precise $^{10}$B demand for alternative boron compounds, with...
Investigation Committee on Nuclear Data (Sigma Committee), established by the Atomic Energy Society of Japan (AESJ) in 1963, has been active for more than 50 years in order to contribute to the further development of nuclear data activities in Japan by examining nuclear data activities in Japan from a broad perspective while keeping an eye on global trends, and by communicating and exchanging...
Accelerator neutrons generated by deuterons are new source for radioisotope (RI) production. In this system, neutrons are produced by the (d, n) reaction by deuteron irradiation on a thick neutron converter made of single element light nuclide such as C or Be. Generated neutrons irradiate the nuclides in a raw material turned into medical RI by direct reactions.
As a feature of the neutron...
Kansas State University measured exposure dose from skyshine radiation using $^{60}$Co sources at Kansas in 1977 [1]. Mitsubishi Nuclear Fuel (MNF) performed calculation of this experiment with a three-dimensional Monte Carlo code PHITS v3.24 (Particle and Heavy Ion Transport code System), which is developed by JAEA [2].
For nuclear facilities, it is necessary to calculate the exposure dose...
Accurate estimation of uncertainties, induced by those of nuclear data through error propagation, of quantities calculated by neutron transport calculation is crucially important for Verification and Validation (V&V) of design and safety analysis of nuclear systems. In this paper, uncertainty in neutron dose after penetrating a 3-m-thick concrete with $^{235}$U thermal fission neutron source...
Radiation-induced biological effects such as cell death and mutation are believed to be attributed to initial DNA damage induction by energy deposition (physical processes) and reactions of chemical products to DNA (chemical processes). The mechanisms of DNA damage induction remain unclear. To make clear the mechanisms, the development of the simulation codes for physical and chemical...
PHIG-3D, developed as a 3D visualization tool for PHITS[1] input data, is oriented toward an intuitive interface. However, its internal structure and functions, which are difficult to describe in the document, have not been described clearly.
The most significant limitation in PHIG-3D is the large amount of memory used when using the lattice structure. After reading the input file, PHIG-3D...
The High Temperature Engineering Test Reactor (HTTR) has achieved at its first criticality in 1998. Before the first criticality approach, first criticality prediction had been carried out using Monte Carlo code MVP with JENDL3.3 but it missed the first criticality point.
The MVP of that time could not treat stochastic geometry model. Therefore, the effect of double heterogeneity of coated...
Since the experimental nuclear data is scarce in the kinetic energy region around GeV, which is crucial for high-power proton accelerators, such as Accelerator Driven System (ADS), 3-GeV synchrotron called RCS (Rapid Cycling Synchrotron) and beam transport facility 3NBT, conveying the beam from 3-GeV synchrotron to Material Life Science Experimental facility (MLF), play important roles in...
Supercritical Water-cooled Reactor (SCWR) is the only water-cooled reactor among the six Generation IV reactor concepts. It is the logical evolution of the current Light Water-cooled Reactor (LWR) as it follows the historical development of fossil fuel-fired power plant, which has been operating at the supercritical pressure of water since 1970s. The SCWR plant concept may be characterized by...
In carbon-ion radiotherapy, the treatment plan is verified by comparing the planned dose and measured dose before treatment. The dose measurement is limited to a portion of the three-dimensional (3D) irradiation region of interest. Gel dosimeters can measure the 3D absorbed dose distribution using the reaction between radiation-sensitive dye and radicals generated by radiation exposure....
Radiation and particle transport calculations based on the Monte Carlo method have been effectively used in various fields and are also now indispensable tools for the researchers and engineers involved. We have utilized the PHITS code mainly for medical applications, radiation protection, radiation activation evaluation for medical accelerator, and next generation fusion reactor development....
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The nuclear muon capture reaction is the capture of a negative muon by a proton in a nuclear medium via weak interaction from the 1s state of the muonic atom. When the muon stops in the matter, the muonic atom is formed and deexcited to the 1s state by emitting muonic X-rays. The reaction probability of the muon capture is more than 90% for the muonic atom with heavy elements. The excitation...
In recent years, there have been many attempts to generate nuclear data using machine learning. Following this trend, we are trying to generate nuclear data by combining machine learning and nuclear reaction models. In this presentation, we will present the award-winning paper " Nuclear data generation by machine learning (I) application to angular distributions for nucleon-nucleus scattering"...
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The author has studied various types of innovative fission reactors with different nuclear fuels and expanding applications of nuclear energy released by neutron reactions or disintegrations of radioisotopes, aiming at utilization in many fields including space, medical diagnostics/therapy, planetary science, etc.
In the vast of those studies with different purposes, unique materials and...
We conducted a simulation analysis of the behavior of cosmic-ray muons (CRM) passing through a huge mountain using the newly established cosmic-ray muon mode in PHITS. In this analysis, we investigated various aspects, including the altitude and angle dependence of incident and transmitted muons, further attenuation of decelerated muons after transmission of massive mountain by atmosphere, and...
An activation experiment using aluminum samples at the CHARM [1] of CERN was simulated for a benchmark on the radiation shielding of high energy accelerators. Na-24 production in aluminum samples set in the irradiation room and corridor of the CHARM was calculated. Additionally, measurable feasibility of other activated nuclides produced in the aluminum sample was checked.
Two radiation...
Palladium is one of the nuclides targeted for recycling from spent nuclear fuel. Reasonable nuclear reaction paths for $^{107}$Pd and the cross-sections for proton- and deuteron-induced spallation in inverse kinematics have been investigated [1]. However, a transmutation experiment using long-lived fission products as the target would be required for an actual system. To experimentally...
