Strontium-90 is one of the most important fission products due to the potential health risks of its uptake and retention in the human body. Conventional analysis techniques involve β counting, which requires ingrowth of 90Y over a period of two weeks. Accelerator mass spectrometry (AMS) has the potential to shorten the analysis time while offering a lower limit of detection than β counting. Here, Sr

The new critical assembly STACY will be able to contribute to the validation of criticality calculations related to the fuel debris. The experimental core designs are in progress in the frame of JAEA/IRSN collaboration. This paper presents the method applied to optimize the design of the new STACY core to measure the criticality characteristics of pseudo fuel debris that simulated Molten Core Concrete

A novel amine-functionalized magnetic large-pore SBA-15 obtained via in situ approach and the post-grafting method was employed as a new adsorbent for removal of uranium from aqueous solutions. Results indicated that the as-prepared adsorbent exhibited fast adsorption rates in the first hour, at the optimum pH 6. The adsorption process was fitted well to the Langmuir isothermal and the maximum adsorption

At Japan Atomic Energy Agency (JAEA) MOX fuel facilities, a worker usually wears a protective lead apron; therefore, the dose to the lens of the eye (lens dose) outside the apron is higher than that to the torso. To estimate the potential impact on the current facility operation of the International Commission of Radiological Protection (ICRP)-proposed lens dose limit reduction from 150 mSv/y to average

NO2 and NO generated during a boiling and drying accident, which affects the release of volatilized radioactive Ru into the atmosphere, were examined using various samples including simulated high-level liquid waste and a thermogravimetric analyzer. NO2 and NO in the gas flowing out of the analyzer were measured separately using a NOx analyzer equipped with NO2 and NO sensors. The samples were heated

Continuum strength function for the isoscalar monopole (IS0) and dipole (IS1) transitions in the α +   40 Ca system is investigated on the basis of the orthogonality condition model (OCM) under the absorbing boundary condition (ABC). The nuclear potentials are constructed from the double folding procedure with the effective nucleon–nucleon interaction of the density-dependent Michigan three range Yukawa

A security issue on nuclear facilities will give a significant effect on national security, economy, public health, or the combination among them. The evaluation of physical security effectiveness is done by considering it as a probability that the system will defeat an adversary at a particular time. This research examined the effectiveness of Physical Protection Systems (PPS) of a nuclear research

Hitachi has developed the chemical decontamination method to remove radioactive oxides on structural materials by alternately using a mixed solution of oxalic acid and hydrazine for a reductive process and potassium permanganate or permanganic acid solution for an oxidative process. In the decontamination of carbon steel (CS) by applying oxalic acid, a film of iron(II) oxalate dihydrate that has low

The effect of solution annealing and aging treatment on the intergranular carbide precipitation behavior of alloy 690 tubes for steam generators is investigated. The carbides precipitated on the grain boundaries were identified as chromium-rich M23C6 carbide, which has a cube-cube orientation relationship with the matrix on one side of neighboring grains. The carbide precipitation behavior is closely

Tungsten is widely used as a plasma-facing material in nuclear fusion reactors due to its favorable properties; however, the extensive exposure of energetic particles could lead to severe degradations on its surface. Therefore, we studied the surface modification resulted from helium implantation on the mechanically and electrochemically polished tungsten at an elevated temperature. Samples of both

In connection with the accuracy of the 10B(n, α) cross section in the thermal- and epithermal-neutron energy regions, criticality calculation results were examined for six benchmark sets of light-water-moderation critical experiments of UO2 and MOX fuel lattice cores with un-borated and borated water. Two of the benchmark sets were those implemented in the Tank-Type Critical Assembly (TCA). The others

The sources and mechanisms for the tritium release into the primary coolant in the JMTR and the JRR-3M containing beryllium reflectors are evaluated. It is found that the recoil release from chain reaction of 9Be is dominant and its calculation results agree well with trends derived from the measured variation of tritium concentration in the primary coolant. It also indicates that the simple calculation

Suppressing the kernel migration rates under normal operation condition is quite important from the viewpoint of the fuel integrity for High-Temperature Gas-cooled Reactors. It depends on both the fuel temperature and the fuel temperature gradient. The presence of the ideal axial power distribution to minimize the maximum kernel migration rate allows us to improve the efficiency of design work. Therefore

A reduced order model (ROM) for a safety analysis code (RELAP/SCDAPSIM) is developed and is applied to the statistical safety analysis in order to reduce computational load. The ROM that reproduces output of the safety analysis code (e.g., the peak cladding temperature) is constructed using the singular value decomposition and the low-rank approximation for time-series data of a safety analysis code

ABSTRACT Air dose rates within a range of 80 km from the Fukushima Dai-ichi Nuclear Power Plant measured via car-borne surveys using the KURAMA systems from 2011 to 2018 were analyzed. The ratio of the air dose rates relative to the first car-borne survey was 0.08 over a period of seven years, indicating a much more rapid decrease than that estimated by the physical decay of radiocesium (0.3). Differences

The nuclear security has been considered for the industrial terrorism preventions. In the fourth industrial revolution era, our life related systems are connected each other, which means the internet based networking is spread anywhere. It is suggested to make the modeling for the nuclear security in cyber information where the computer hacking is one of major incidents. The data and information could

Emphasis has been placed on the behavior of ruthenium (Ru) in the evaporation to dryness accident due to the loss of cooling functions (EDLCF) of high-level liquid waste in fuel reprocessing plants. It is because Ru would form volatile compounds such as ruthenium tetroxide (RuO4) and could be released into the environment with other coexisting gasses such as nitric acid (HNO3), water (H2O). To contribute

In order to clarify the cesium iodide (CsI) transport behavior with a focus on the mechanisms of gaseous iodine formation in the reactor coolant system of light water reactor (LWR) under a severe accident condition, a reproductive experiment of CsI transport behavior was conducted using a facility equipped with a thermal gradient tube. Various analyses on deposits and airborne materials during transportation

The tritium exhaust behavior from the Large Helical Device (LHD) was observed in the first deuterium plasma experimental campaign. Tritium in the exhaust gas was monitored at the conducted by use of the ionization chamber and water bubbler system with the discrimination of chemical forms. The observation results indicated that (i) tritium on the surface of the first wall and divertor tiles as plasma

The influence of materials of mineral-insulated (MI) cables on their electrical characteristics upon exposure to high-temperature conditions was examined via a transmission test, in the objective of achieving the stability of the potential distribution along the cable length. Occurrence of a voltage drop along the cable was confirmed for aluminum oxide (Al2O3) and magnesium oxide (MgO), as insulating

The passive gamma spectroscopy (PGS) is a useful technique to extract information on spent nuclear fuels without any destructive actions. This method requires a correlation between number densities (NDs) of target nuclides, and it is generally estimated by numerical simulation. Therefore, the prediction accuracy of these nuclide generations is one of the key issues in PGS. Nuclear data used in nuclear

In order to know the performance of evaluated nuclear data in reactor physics or radiation shielding calculations, its benchmark testing with integral data is mandatory. Nowadays we have a huge amount of integral data, but some of them are quite similar to each other. We need to know the independency of available integral data, and also to choose a proper set of a limited number of integral data for

The flexible fuel cycle initiative system (FFCI system) has been developed to reduce spent fuel (SF) amounts, to keep high availability factor for the reprocessing plant and to increase the proliferation resistance for the recovered plutonium (Pu). The system separates most uranium (U) from the SF at first and the residual material called recycle material (RM) which contains Pu, minor actinides (MA)

The dissolution behavior of hydrogen (H) at Fe/W interface and the effect of H on the strength of Fe/W interface are investigated by means of first-principle calculation. The dissolution of H atom at Fe/W interface would be easier than in bulk Fe or W due to the low charge density at Fe/W interface caused by the distortion of lattice. Hydrogen atom prefers to stay at Fe side of Fe/W interface due to

In this paper, a new particle-grid hybrid method is used for numerical simulations of the gas-liquid two phase flow. In this method, the main area of the fluid is calculated via the constrained interpolated profile/multi-moment method (CIP/MM FVM), and the interface of the two phases is calculated by the finite volume particle method (FVP). In the numerical calculation, the particles are distributed

Identification of flow regime and feature extraction of bubble characteristics in gas-liquid two-phase flow systems have been significant issues in various engineering disciplines, including nuclear thermal-hydraulics field. In nuclear safety analysis codes, flow regime transition criteria and bubble size-dependent correlations are often utilized to obtain solutions for the governing equations. However

This paper presents a VVER-1000 coolant transient benchmark calculated using Serpent 2 generated group constants in the reactor dynamics code HEXTRAN coupled with the system code SMABRE. Two different sets of group constants applying different leakage correction methods are generated. The purpose of the paper is to validate the Serpent 2-HEXTRAN–SMABRE code sequence in plant transient calculations

In this study, a compact fiber-optic laser-induced breakdown spectroscopy (LIBS) system was developed using a microchip laser (MCL) with a monolithic Nd:YAG/Cr:YAG composite ceramic, for remote analysis of hazardous environments, such as nuclear reactor cores. Short duration laser pulses exhibiting a near-Gaussian beam profile were obtained. The output properties of the laser, such as pulse energy

For a highly enriched uranium subcritical core driven by an inherent or an external Am-Be source in Kyoto University Critical Assembly (KUCA), a series of the source multiplication measurements, the Feynman-α and the Rossi-α neutron correlation analyses was carried out to demonstrate quantitatively that the use of the former inherent source had some advantages over that of the latter external source

Titanate adsorbents have been used to remove Sr radioisotopes from contaminated water at the Fukushima Daiichi Nuclear Power Station site. This process leads to the generation of spent adsorbents, which require stabilization for long term storage and disposal. Geopolymers are candidates for matrices to achieve this consolidation. However, more data are needed to assess the leaching behavior of Sr from

To estimate the structural damages of materials in accelerator facilities, displacement per atom (dpa) is widely employed as a damage index, calculated based on the displacement cross-section obtained using a calculation model. Although dpa is applied as standard, the experimental data of the displacement cross-section for a proton in the energy region above 20 MeV are scarce. Among the calculation

In the event of a severe accident, past experiences such as Three Mile Island and Fukushima Daichi have shown that the reactor core of a light-water nuclear reactor, if not properly safeguarded, could go through a meltdown. This will be followed by the formation of a corium, a mix of molten fuel elements, and liquid metals from the Reactor Pressure Vessel (RPV). In the worst-case scenario, a melt through

In the event of a severe accident, past experiences such as Three Mile Island and Fukushima Daichi have shown that the reactor core of a light-water nuclear reactor, if not properly safeguarded, could go through a meltdown. This will be followed by the formation of a corium, a mix of molten fuel elements, and liquid metals from the Reactor Pressure Vessel (RPV). In the worst-case scenario, a melt through

The interaction of cesium hydroxide and a calcium silicate insulation material was experimentally investigated at high-temperature conditions to evaluate the possibility of unprecedented cesium retention under severe accident of boiling water reactor. The temperature where the interactions occurred and chemical species of cesium after the interaction were examined in this study. A thermogravimetry

Anomaly detection in vibration signals is an important technique for fault diagnosis, monitoring, and maintenance in nuclear power plants. Therefore, various signal-analysis methods that apply statistical, machine-learning, and deep-learning techniques have been proposed. In particular, deep neural networks (DNNs) have excellent recognition accuracy and do not require the designing of a feature extractor

In the lower chamber of pressurized water reactor (PWR), the flow distribution device is the core module to distribute coolant into the core. It has complex structure and numerous design parameters. Therefore, it has important theoretical and practical significance to optimize the device. The mesh independence verification, turbulence model selection, and data processing all can influence the numerical

After the termination of a loss-of-coolant accident (LOCA), the reactor continues to be cooled for a long term until fuel assemblies are withdrawn from the reactor core. The fuel cladding tube degrades in strength due to high-temperature oxidation during a LOCA event. It is important to confirm that fuel rods exposed to LOCA conditions can withstand earthquakes during the long-term cooling in terms

Present safeguards verification methods for small samples of high-radioactivity nuclear material (e.g. spent nuclear fuel solution) in reprocessing facilities use destructive analysis techniques since passive non-destructive techniques are incapable of directly determining the nuclear material content. To supplement these methods, the Japan Atomic Energy Agency and European Commission Joint Research

When water contacts with porous materials, water and chemical species dissolved in the water transfer into the inside of the porous materials. Here, to study the transfer of uranyl and europium ions on a dry silica gel plate, we dropped a small amount of aqueous solution (~0.5 μL) dissolving the two ions on a dry silica gel plate, and the distributions of the two ions spread on the silica gel plate

In the nations which have nuclear facilities, the precautionary urgent protective action based on the emergency action levels (EALs) is adopted for the decision-making in the early phase of nuclear disaster in line with the strategy introduced in the Safety Standards of International Atomic Energy Agency (IAEA). In this phase, the decision-makers are forced to make choices from the evacuation or the

BackSide-Illuminated (BSI) CMOS Image Sensors (CISs), with developed performance on quantum efficiency and sensitivity, have been applied for aerospace missions and gradually replaced FrontSide-Illuminated (FSI) CISs. Two types of BSI CISs with different epitaxial layer thicknesses were irradiated by 14-MeV neutron up to 3.40 × 1011 n/cm2 to analyze the degradation induced by neutron irradiation. Dark

The physical implication of the eigenfunction of the adjoint of the natural mode equation is studied. The eigenfunction at a phase space position is theoretically derived to be proportional to the amplitude of the neutron flux sufficiently long time after a source is placed at the position. Meanwhile, the time change rate and distribution of the neutron flux originated in the source must converge to

A deep-penetration shielding experiment was performed at the CERN High-energy AcceleRator Mixed-field (CHARM) facility. The protons (24 GeV/c) were injected into a 50-cm-thick copper target and the released neutrons were transmitted through a bulk concrete shield located vertically upward from the target, where they were measured with bismuth and aluminum activation detectors placed at various penetration

A new approach to solve the inverse equation of point kinetics is presented. The neutron density history can be considered as a series of infinite Bernoulli numbers. In order to simplify the problem, the proposed method uses an approximation which considers only two derivatives of the neutron population density. The reactivity is calculated for different forms of neutron population density and for

A new gap conductance model is proposed in this study as a combination of Toptan’s model and the Ross-Stoute model. A variance-based sensitivity analysis is performed to understand how simulation results depend on all input parameters of the proposed model. Additionally, new modeling options (e.g. fill gas thermal conductivity, temperature jump distance, thermal accommodation coefficient, etc.) are

Introduction Studies on migration behaviors of colloidal materials through engineered and natural barriers are highly important for the safety assessment of radioactive waste repositories since the fate and transport of radionuclides may be significantly affected by interactions with colloids.Methods: Poly (ethylene glycol) coated gold nanoparticles (AuNPs) were used as a model colloid and the effects

After direct discharges of highly contaminated water of the Fukushima Daiichi Nuclear Power Plant (1 F) from April to May 2011, Kanda suggested that relatively small amounts of run-off of radionuclides from the 1 F port into the Fukushima coastal region subsequently continued by his estimation method. However, the estimation period was limited to up to September 2012. Therefore, this paper estimatesthe

In-vessel retention (IVR) is a strategy for severe accident management in which the lower head of the reactor vessel is submerged in a water-flooded reactor cavity. Critical heat flux (CHF) data for IVR are important for estimating cooling capacity of the reactor vessel. The existing CHF data for IVR which were obtained for the specific geometries and thermal-hydraulic conditions of actual plants are

A new approach for generating nuclear data from experimental cross-section data is presented based on Gaussian process regression. This paper focuses on the generation of nuclear data for proton-induced nuclide production cross-sections with a nickel target. Our results provide reasonable regression curves and corresponding uncertainties and demonstrate that this approach is effective for generating

An effective dose calculation method is important in the design of efficient shields in radiation facilities. Some analytical methods have been shown to provide a simple and quick design analysis; however, no suitable method exists that can be applied to a room located directly under an X-ray irradiation room. We propose a new analytical method that uses the multiple reflection ratio predetermined

Governing the rate of heat transport by condenser tubes in the passive containment cooling system (PCCS), the steam condensation over a vertical cylinder in the presence of air was investigated experimentally. The main objective of this study was to explore if the condensation heat transfer coefficient relies on the tube dimension, which has been a variable missed in most condensation models or has

An equation of power in subcritical quasi-steady state has been derived based on one-point kinetics equations for the purpose of utilizing it for the development of timely reactivity estimation from complicated time profile of neutron count rate. It linearly relates power, P, to a new variable q, which is a function of time differential of the power. It has been confirmed that the points (q, P) calculated

After the core meltdown in the Fukushima Daiichi (1F) nuclear power plant, various compounds in metal boride systems could potentially form as a result of the reactions between B4C (control material) and Fe, Zr alloys (control-blade sheaths, zircaloy claddings, channel box, etc.). Some previous studies have focused on the properties of intermetallic compounds of the Zr-B and Fe-B systems, such as ZrB2

Measuring the surface tension of molten ZrO2 is critical to determine the progression of a severe accident in a nuclear power plant. However, no experimental reports have been published pertaining to the surface tension of liquid ZrO2 because of its high melting point, high reactivity, and high vapor pressure, among other factors. Thus, in this study, the surface tension of ZrO2 was measured by using

In order to evaluate the accuracies of the kinetics parameters predicted with the continuous-energy Monte Carlo calculation code, MVP3, core analysis was performed for light-water moderated UO2 and mixed oxide (MOX) fuel cores for which the ratios of effective delayed-neutron fraction (βeff ) to prompt-neutron life time (ℓ) – represented hereafter by βeff /ℓ – and βeff values were measured. The results

Investigated numerically are the effects of the rotational speed of the screw conveyor and the reactor temperature on the changes in the diameter of graphite particles passing through a laboratory-scale enclosed screw-conveyor reactor. Also investigated experimentally are a thermal gasification of graphite particles to carbon–oxygen compounds to determine a kinetic reaction model and kinetic parameters

An uncertainty analysis of the OECD/NEA LWR UAM benchmark Phase I was performed by CASMO5 using JENDL-4.0 and ENDF/B-VII.1, and the individual influence of nuclide/reaction covariance data was estimated to preliminary discuss the important covariance data on the uncertainties of lattice physics parameters used in core calculations. In the boiling water reactor and pressurized water reactor UO2 fuel

The pebble-bed type reactor is one of the mainstreams for high-temperature gas-cooled reactor (HTGR), whose core is a packed bed composed of numerous spherical pebbles. In this work, discrete element model (DEM) is used to simulate the pebble flows in a thin pebble bed, and the packing peaks, top angles, trajectory and velocity deviations, retention time, and ratios are analyzed in detail. The effects

The low temperature heat capacity of Cs2Si4O9, which is one of the cesium chemisorbed compounds onto stainless steel during severe accidents of the light water nuclear reactor, was experimentally determined for the first time in the temperature range of 1.9–302 K. The experimentally determined heat capacity, Cp o (298.15 K), and the standard entropy, So (298.15 K), were 249.4 ± 1.1 J K−1 mol−1 and

As the main control room of nuclear power plants (NPPs) has been gradually digitized, new human reliability problems may emerge because of a series of new changes in the cognitive processes, behavioral patterns, and error mechanisms of operators. Aiming to address this situation, this paper proposes a method as guidance for human reliability analysis (HRA) of different cognitive Stages. This method