ABSTRACT This article is devoted to demonstrate the feasibility of laser cutting technique for the fuel debris retrieval into the Fukushima Daiichi damaged reactors. IRSN is involved in a project led by ONET Technologies, in collaboration with CEA, to evaluate the risk occurred by the dispersion of aerosols emitted by the dismantling operations [4]. During the laser cutting operations of fuel debris

ABSTRACT Extraction behavior of Pd(II) and Re(VII) from HNO3 aqueous solutions (0.1–5.0 M, M = mol∙dm−3) to CH2Cl2 containing N-cycrohexyl-2-pyrrolidone (NCP, 0.1–2.0 M) as an extractant has been examined. As a result, it was found that distribution ratios (D) of Pd(II) and Re(VII) under [HNO3] = 3.0 M increase with increasing [NCP] from 0.1 to 2.0 M and that plots of log D vs. log[NCP] show linear

ABSTRACT An electrodeposited thorium target and a ThO2 sample were irradiated together with fast neutrons using the Chinese Fast Burst Reactor II. The activities of 233Pa in both samples were measured and compared to determine the mass of 232Th deposited on the target. Experimental results showed that the mass of deposited 232Th was 19.6 μg, and the uncertainty was estimated to be 1.4%.

(2021). Microparticles with diverse sizes and morphologies from mechanical and laser cutting of fuel debris simulants and geopolymer as a covering material. Journal of Nuclear Science and Technology. Ahead of Print.

ABSTRACT The neutron capture cross sections of   244 C m and   246 C m were measured for the neutron energy range of 1–1000 eV via the neutron time-of-flight method with Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) at Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). The world’s most intense neutron pulses from the

ABSTRACT Crack detection is one of the important contents of the nuclear fuel pellet quality inspection. Aiming at the problem of high crack false detection rate caused by low image contrast of nuclear fuel pellets, complex image background and fine cracks on the pellet surface, a Weighted Object Variance (WOV) threshold crack detection method guided by SE-CrackNet convolutional neural network is proposed

ABSTRACT Degradation mechanism involving the interaction between the U-Zr-O phase from molten fuel cladding and steel was investigated at the lower structure of core region of the boiling water reactor, which could take place at low temperatures compared to the failure conditions typically assumed in the current severe accident codes. The non-isothermal interaction was simulated by the heat and mass

ABSTRACT Commissioning is a final technical barrier for nuclear power engineering projects, the occupational stresses of commissioning workers make nuclear power projects face great human factor safety risk. A bottom-up methodology and factor analysis were adopted to identify the occupational stress factors of commissioning workers in NPPs, whereby the authors firstly made a field survey on the commissioning

ABSTRACT The uniaxial tensile and fracture properties are the basic data for the structural integrity assessment of ductile material. In this study, the stress-strain relations of ductile materials are predicted by the SPT-related stress-strain relation (SPT-SR) model directly through SPT experiment, which agree with the relations determined by the finite-element-analysis aided testing (FAT) method

ABSTRACT Cathode ray tubes (CRTs) are glass materials that contain harmful heavy metal elements such as lead . CRTs have been widely used in electronic products sets for decades. At present, these discarded CRTs endanger the environment. Because the high-density heavy metal elements in CRTs have a good shielding effect for X/γ rays, these raw materials have become a good choice to produce radiation-proof

ABSTRACT Aggregates of acicular RuO2 occur in high-level waste glass. Large aggregates may settle rapidly in the glass, providing a more efficient electrical path on the melter bottom and interfering with the Joule heating of the glass. To clarify the formation mechanism of aggregates and to develop countermeasures to such formation, chemical reactions between RuO2 and NaNO3 with/without borosilicate

ABSTRACT Zirconium coating on Zirconium-Niobium alloy substrate was obtained by pulsed current electrodeposition from FLINAK-K2ZrF6 molten salt at 1023 K in argon atmosphere. The microstructure and morphology of the coating were investigated. The adhesion between coating and substrate, porosity of the coating surface was tested. Metallic zirconium crystal of zirconium coating is a hexagonal crystal

ABSTRACT Lead-cooled fast reactor (LFR) is one important candidate for the advanced reactors for future sustainable energy supply due to its excellent inherent safety and economic characteristics. The fuel management scheme of LFR affects application potentials and fuel cycle scheme of the entire nuclear system. In order to research the establishment and evaluation of the mixed refueling scheme for

ABSTRACT SLUMBAT is a framework for nuclear material accounting and reporting on a permissioned blockchain. Testing SLUMBAT for a nuclear fuel supply scenario involving two State systems of accounting for and control of nuclear material (SSAC), and their national and international regulators, is used to investigate the application of blockchain technology to nuclear non-proliferation. SLUMBAT shows

ABSTRACT The D/W pressure at Fukushima Daiichi Nuclear Power Plant Unit-2 dropped from 0.73 MPa [abs] to 0.155 MPa [abs] between 7:20 and 11:20 on the March15th, 2011. We assumed gas leakage from the PCV and steam condensation in the PCV as factors of this depressurization, and examined the feasibility of the accident progression scenario based on the observation facts obtained from the site. In case

ABSTRACT Accurate thermal neutron scattering cross-section data of the Bismuth (Bi) filter is required for high-fidelity calculations of the thermal neutron beam’s performance after the filtration in reactor column. In this paper, the phonon density of states of Bi was calculated using the ab initio method, based on which the thermal neutron scattering cross-section data was generated by the introduction

ABSTRACT Radiation dose rate effects on the properties of a compact fiber-optic laser-induced breakdown spectroscopy (LIBS) system with a monolithic Nd:YAG/Cr:YAG composite ceramics were investigated for remote analysis in a hazardous environment. To investigate radiation effects on the LIBS signal, properties related to the Nd:YAG laser operation such as oscillation threshold, output energy, oscillation

ABSTRACT We report an ensemble approach applied to the radiation dose modeling for a hypothetical radiation emergency with a long-term release of radioactive materials into the atmosphere. The study is aimed at improving the emergency response system in Russia and focuses on quantifying the impact of meteorological uncertainties on modeling the atmospheric dispersion and transport. Four sets of options

ABSTRACT Gamma emission tomography (GET) detects fuel rods that emit gamma rays for potential use as verification tools in nuclear safeguards. In GET, iterative reconstruction algorithms are often used to reconstruct passive gamma-ray emitter source distributions. Generally, using noisy sinogram data, the iterative reconstruction algorithms increase the noise level on a reconstruction image with iterations

ABSTRACT Studtite and metastudtite are uranyl peroxides formed on nuclear fuel in water through the reaction with H2O2 produced by the radiolysis of water. However, it is unclear how the two types of uranyl peroxides are generated and distributed on the surface of nuclear fuel. Here, we used Raman imaging technique to exemplify distribution data of the two uranyl peroxides formed on the surface of

ABSTRACT After the accident at TEPCO’s Fukushima Daiichi Nuclear Power Plant, in Japan, the scope of the safety regulation requirement was expanded from the level 3 (control of accidents within the design basis) of Defence in Depth (DiD) to the level 4 (measure of severe accidents), and measures related to the level 5 (off-site emergency response) were strengthened. Based on the characteristics of

ABSTRACT The Japan Atomic Energy Agency (JAEA) has designed a Transmutation Physics Experimental Facility (TEF-P) as an experimental facility in the Japan Proton Accelerator Research Complex (J-PARC). The TEF-P is a critical assembly driven by a low-power proton beam, a maximum of 10 W, which is extracted from a high-power beam source, such as 250 kW of 400 MeV proton beam of the J-PARC linac. To extract

ABSTRACT In February 2019, TEPCO and TOSHIBA designed a robot that can handle the debris, performed a trial investigation of primary containment vessel (PCV) of the Fukushima Dai-Ichi (1F) Unit 2 and published a video. The video contained lots of valuable information which can be compared with results of BWR control blade degradation tests recently performed in Japan Atomic Energy Agency (JAEA). During

ABSTRACT The formation of hydrogen gas in the water circuits of nuclear power plants has implications for the safe and efficient operation of the plant and so requires thorough investigation. Therefore, typical metal oxides found on water circuit structural material surfaces have been subjected to γ-radiation in water, and the production of H2 by radiolysis has been analysed as a function of oxide

(2020). Correction. Journal of Nuclear Science and Technology. Ahead of Print.

ABSTRACT Soft and hard epoxy resins used as insulating sealants in nuclear power plants were aged simultaneously by heat and gamma rays at 80, 90, and 100°C, and the changes in their various properties induced as a result of their degradation were measured. The thermal, mechanical, dielectric, and spectroscopic properties hardly change in the hard epoxy resin, whereas they change drastically in the

ABSTRACT A new concept of transmutation system for six long-lived fission products (LLFPs: 79Se, 93Zr, 99Tc, 107Pd, 129I, and 135Cs) consisting of three small-size fast reactor cores was proposed. In order to establish a method to estimate the effects of cross-section uncertainties on the transmutation rates of the LLFPs, cross section covariances for the six LLFPs were estimated using a T6 system

ABSTRACT Density-functional theory calculations were applied to mo lecular structure and complex formation reaction modelings of metal ion complexes with diethylenetriaminepentaacetic acid (DTPA) and its bisamide (DTPABA) chelates to understand the metal ion selectivity between Am3+ and Eu3+. The calculated complexes with DTPA and DTPABA chelates reproduced the coordination geometries of experimental

ABSTRACT CMOS image sensors were irradiated by protons of 50 and 70 MeV and the dark current random telegraph signal (RTS) is investigated. After exposure to the protons, the experimental results provide new evidence that confirms the existence of a correlation between radiation-induced hot pixels and RTS pixels. Moreover, the evolutions of the percentage of hot pixels showing RTS behavior at distinct

ABSTRACT We have been developing energy-resolved X-ray computed tomography (ER-CT) using a novel detector system called a transXend detector, which measures X-rays as electric current and gives the energy distribution of X-rays by unfolding analysis. This paper presents the results of the sugar content measurements of kiwifruit samples by ER-CT. Because the change of linear attenuation coefficients

ABSTRACT SAS4A is presently the worldwide standard computer code for simulation of the initiating phase of the Core Disruptive Accident (CDA) in MOX-fueled Sodium-cooled Fast Reactors (SFR). In order to improve the capability of the computational code, SAS4A, to be applied to the safety assessment for SFRs, detailed investigations of physical phenomena under unprotected loss-of-flow (ULOF) conditions

ABSTRACT The effect of initial material strength induced by cold work on the formation of solute atom clusters was investigated for thermal-aged Fe-Cu alloy specimens with and without cold work to understand the effects of material properties before irradiation on radiation embrittlement in reactor pressure vessel (RPV) steels. The results of solute atom cluster analysis by atom probe tomography supported

ABSTRACT The authors developed an evaluation method for planning urgent protection strategies in a nuclear emergency by using a Level 3 Probabilistic Risk Assessment (PRA) code, OSCAAR. For a given accident scenario, the OSCAAR can calculate received doses in the early phase of a nuclear accident and the dose reduction effect of implementing urgent protective actions such as evacuation, sheltering

ABSTRACT Pellet-Cladding Interaction (PCI) is one of the most important issues in fuel rods of a Pressure Water Reactor (PWR) which may cause the failure of fuel rods, and it should be analyzed under operating transients to ensure the fuel rods’ integrity. The traditional PCI analysis method simulates the detailed physical phenomena that occurred in fuel rods and it considers the combined effects of

ABSTRACT For a subcritical reactor system driven by a periodically pulsed spallation neutron source in Kyoto University Critical Assembly, a series of power spectral analysis on frequency domain is carried out to determine the prompt-neutron decay constant and quantitatively to confirm a non-Poisson characteristics of the neutron source. Not only the cross-power but also the auto-power spectral density

ABSTRACT As a result of the Fukushima nuclear power plant accident in March 2011, massive amounts of soil were contaminated with radioactive Cs. To remediate the contaminated soil, we are developing a desorption technique for removing Cs from soil using subcritical water. In the contaminated soil, the radioactive Cs is stably trapped in the interlayers of the clay minerals, making the use of traditional

ABSTRACT Silicone rubber (SiR) is an important electrical insulating material for safety-related cables in nuclear power plants. This means that SiR must withstand the irradiation of gamma rays and the exposure to high-temperature steam. However, SiR is vulnerable to hydrolysis. Therefore, for the purpose of clarifying the behavior of SiR in such environments, sheets of SiR were exposed to steam at

ABSTRACT In the ‘evaporation and dryness due to the loss of cooling functions,’ which is one of the severe accidents at reprocessing plants in Japan, volatile ruthenium (Ru) compound is possible to be produced and released from high level liquid waste (HLLW) in the storage tank to the environment. This cause is considered that the volatile Ru compound is produced from ruthenium nitrosyl nitrate by

ABSTRACT The dissolution behaviors of spent fuel were studied and the secondary precipitate was obtained and characterized. The experimental results showed that the spent fuel sliced to 20–30 mm in length was completely dissolved within 5 hours in 6.5 M nitric acid at about 90°C and the precipitating of Ru happened in the course of dissolution, and the secondary precipitate formed in the following

ABSTRACT 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 light-water moderation UO2 cores loaded with the aqueous solution samples of eight elements (B, Rh, Cs, Nd, Sm, Eu, Gd, and Er). The concentrations of the elements in the solution samples were changed

ABSTRACT In the post-Fukushima accident era, the participation of local residents and their acceptance of nuclear power plants (NPPs) have become significant issues. Using the case of Qinshan NPP in China, this study examined the factors affecting public acceptance of NPPs and explored the ways in which public participation affects the public acceptance of NPPs through structural equation modeling

ABSTRACT The Japan Atomic Energy Agency is evaluating delayed gamma-ray spectroscopy as an active interrogation nondestructive assay technique to quantify the fissile composition of nuclear materials for improved safeguards verification in nuclear fuel cycle facilities. In this paper, we optimize a moderator to thermalize the 2.5 MeV neutrons emitted from a deuterium–deuterium (D–D) neutron generator

ABSTRACT To investigate the leaching behavior of radioactive nuclides in leaching samples comparable to core debris (partially molten ZrO2/UO2 between fuel rods) in the Fukushima Daiichi Nuclear Power Station (1 F NPS), the concentration of radionuclides in the leaching solution was measured. The leaching behaviors of actinides (U, Pu, and Np) and Cs from the samples were similar to those from spent

ABSTRACT Monte Carlo simulations of the void velocity measurement in a light-water moderated critical assembly CROCUS are performed using a continuous energy Monte Carlo code that has a special function to conduct frequency domain calculations using complex-valued weights of neutron noise. In the measurements that are simulated in this paper, two vertically aligned fission chambers detected the neutron

While designing deuteron accelerator neutron sources for radioisotope production, nuclear data for light elements such as Li, Be, and C have been systematically measured in the deuteron energy range from a few MeV to around 50 MeV. Currently, the experimental data available on double-differential thick-target neutron yields (DDTTNYs) are insufficient, especially for deuteron energies between 18 and

The HTGR reactor core is always composed of packed fuel pebbles and helium gas. The fluid flows around spherical particles and cylindrical rods are always encountered in the reactor core of nuclear powers. The flows past the spherical particles and cylindrical rods were simulated here. Two aspects were considered: comparison of heat transfers between the spherical particles and the cylindrical rods

This paper examines free-surface vortices and the vorticity distribution with time-dependent evolution within a closed pump intake under five pressure conditions. The location and the strength of these vortices, occurrence probability and perspective statistics, as well as vortex probability distribution are all systematically analyzed. Three cases were observed and analyzed: (a) Subcritical (Q= 19

The thermal-neutron capture cross sections (σ0) and resonance integrals (I0) were measured for the 243Am(n,γ)244gAm and 243Am(n,γ)244m+gAm reactions by a neutron activation method. Americium-243 samples were irradiated with a pneumatic tube and a hydraulic conveyer installed in the research reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Alloy wires of Au/Al, Co/Al

Hydrogen (H) solubility, segregation, and hydrogen-induced intergranular fractures in eight symmetric tilt grain boundaries (GBs) in tungsten (W) are investigated through the first-principles calculations. The results show that there is an equilibrium distance, about 1.95 Å, between the H inserted in interstitial sites and its nearest W. Interactions between the inserted H and GBs are rather localized

Transient analysis of TMSR-SF0, a molten salt thermal-hydraulic experimental system of molten salt reactor, is investigated using RELAP5/MOD4.0 code. Simulation model consists of two coolant circuits. Variations in core power, primary mass flow, secondary mass flow, and air mass flow are studied separately. Both temporary and permanent phenomena of test facility are concerned in different circumstances

The nano-crystalline materials generally show better irradiation resistance than common poly-crystalline materials since grain boundaries (GBs) can usually enhance the annihilation of irradiation-induced defects. Although the defect annihilation mechanism has been thoroughly investigated in GBs in tungsten, the influences of defect migration behavior in GB-planes on the recombination capability between

An efficient reduced order model (ROM) for time-dependent diffusion calculations using the proper orthogonal decomposition (POD) is proposed. Employing the singular value decomposition (SVD) and low-rank approximation (LRA) for the flux distributions sampled from the detail full order model (FOM) solutions, the orthogonal basis suitable for a target problem is numerically obtained. In the present ROM

Ab initio calculations based on the density functional theory were performed to investigate the interaction between Ni and Si in the body-centred cubic Fe system. The Ni-Si interaction was first evaluated in the framework of small Ni-Si clusters, then followed by detailed analyses. The calculations showed that even though the formation of pure Ni clusters was not energetically favoured, the presence

ABSTRACT A low-noise current-sensitive preamplifier was developed for aiming low-dose X-ray computed tomography with applying a charge-sensitive preamplifier. We compared the number of X-ray photons needed for current measurement with the new preamplifier with that needed with a conventional preamplifier. Also, the dose rates for above conditions were measured by a commercial dose rate meter. Results

The voltage and power of the RF cavity of an accelerator were measured based on a calibration factor of the capacitor probe to assess the performance of the SC200 cavity. The calibration factor can be formulated using a low-frequency method and RF numerical simulation. Thereafter, based on it, the capacitor probe is utilized to measure the voltage and power of the RF cavity in a cool-measured and high-power

The independent and cumulative fission product yields (FPYs) and their covariance matrices were newly evaluated for thermal- and fast-neutron induced fission and spontaneous fission. We principally evaluated the independent isobaric charge distributions by taking account of available experimental data, especially putting emphasis on the shell and even-odd staggering in the fission yields by applying

ABSTRACT The production and dispersion of contaminated aerosols during the laser cutting of corium can potentially provide useful insights into the dispersion of contamination during the evacuation of damaged reactors during decommissioning. Quantitative assessments of contamination dispersion are fundamental to the development of a safety case for the decommissioning of the Fukushima Daiichi plant

ABSTRACT For a subcritical reactor system driven by a periodically pulsed spallation neutron source in Kyoto University Critical Assembly (KUCA), the Feynman-α and the Rossi-α neutron correlation analyses were carried out to determine the prompt-neutron decay constant and quantitatively to confirm a non-Poisson characteristics of the neutron source. In these correlation analyses, a non-negligible contribution

ABSTRACT It is important to perform neutron transport simulations with accurate nuclear data in the neutronics design of a fusion reactor. However, absolute values of large-angle scattering cross sections vary among nuclear data libraries even for well-examined nuclide of iron. Benchmark experiments focusing on large-angle scattering cross sections were thus performed to confirm the correctness of

ABSTRACT The concept of Pu-burner high temperature gas-cooled reactor (HTGR) has been proposed to more safely reduce the amount of recovered Pu. In the Pu-burner HTGR concept, coated fuel particles with ZrC-coated yttria-stabilized zirconia containing PuO2 (PuO2-YSZ) kernels are employed for very high burn-up and high nuclear proliferation resistance. The role of ZrC layer is that of oxygen getter