Showing papers in "Journal of Nuclear Science and Technology in 2015"
TL;DR: In this article, the BEAVRS (Benchmark for Evaluation and Validation of Reactor Simulation) benchmark is solved by the nTRACER direct whole core calculation code to assess its accuracy and to examine the solution.
Abstract: The BEAVRS (Benchmark for Evaluation and Validation of Reactor Simulation) benchmark is solved by the nTRACER direct whole core calculation code to assess its accuracy and to examine the solution d...
53 citations
TL;DR: In this paper, the alloying effects of Sn, Nb, Cr, and Mo on zirconium alloys were elucidated and compared, and it was shown that Mo is the most effective among these elements from the viewpoints of strengthening and reducing grain size.
Abstract: The alloying effects of Sn, Nb, Cr, and Mo on zirconium alloys were elucidated and compared. Electron backscatter diffraction, transmission electron microscopy, tensile test, and fractographic observation were jointly utilized to carry out detailed microstructural characterization and mechanical property evaluation. Results show that Mo is the most effective among these elements from the viewpoints of strengthening and reducing grain size. The strengthening mechanism for each element is also discussed. The order of solid-solution strengthening of these alloying elements is Cr > Nb > Sn, and the sequence is Cr ≈ Mo > Nb when precipitation strengthening is considered. Further, as far as the ability to impede dislocation motion is concerned, the sequence is Mo > Cr > Nb > Sn. The experimental results demonstrate that minor amount of Mo addition in zirconium alloys is greatly effective in strengthening the alloy and reducing the grain size.
46 citations
TL;DR: Silicon carbide (SiC) coating is one of the countermeasures for the prevention of oxidation and hydrogen embrittlement of fuel claddings because SiC has high resistance of oxidation.
Abstract: Silicon carbide (SiC) coating is one of the countermeasures for the prevention of oxidation and hydrogen embrittlement of fuel claddings because SiC has high resistance of oxidation and hydrogen pe...
45 citations
TL;DR: In this paper, a nonwoven fabric impregnated with potassium zinc ferrocyanide (Zn-C) was used to effectively concentrate and quantify cesium dissolved in water.
Abstract: This paper presents a cartridge filter incorporating a nonwoven fabric impregnated with potassium zinc ferrocyanide (Zn-C) to effectively concentrate and quantify cesium dissolved in water. Experiments conducted with 137Cs in conditioned water showed that at a flow rate of 2.5 L/min the filter could absorb 97.9% of dissolved 137Cs from 20 L of water; high recovery efficiency was achieved over a pH range of 3–10. Test measurements of 137Cs concentrations using Zn-C in river water agreed with the results derived by using an evaporative concentration method (within the counting error of the detector). Using this method, the pre-concentration time of radiocesium in 20 L of fresh water can be reduced to just 8 minutes.
39 citations
TL;DR: The Multi-purpose Hybrid Research Reactor for High-tech Applications (MYRRHA) is a multi-purpose research facility currently being developed at SCK•CEN as mentioned in this paper.
Abstract: MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) is a multi-purpose research facility currently being developed at SCK•CEN. It will be able to work in both critical and sub...
30 citations
TL;DR: In this article, the authors provide a state-of-the-art review of seismic protection systems in nuclear engineering and to answer four significant research questions: (1) why SPS is not adopted in the nuclear industry and what issues have prevented their deployment? (2) what types of SPS are being considered in nuclear energy engineering research? (3) what are the strategies for location of the SPS within nuclear power plants (NPPs) and (4) how may SPS provide improved structural performance and safety of NPPs under seismic actions.
Abstract: Seismic protection systems (SPS) have been developed and used successfully in conventional structures, but their applications in nuclear power plants (NPPs) are scarce. However, valuable research has been conducted worldwide to include SPS in nuclear engineering design. This study aims to provide a state-of-the-art review of SPS in nuclear engineering and to answer four significant research questions: (1) why are SPS not adopted in the nuclear industry and what issues have prevented their deployment? (2) what types of SPS are being considered in nuclear engineering research? (3) what are the strategies for location of SPS within NPPs? and (4) how may SPS provide improved structural performance and safety of NPPs under seismic actions? This review is conducted following the procedures of systematic reviews, where possible.The issues concerning the use of SPS in NPPs are identified: cost, safety, licensing and scarcity of applications. NPPs demand full structural integrity and reactor's safe shutdown during...
29 citations
TL;DR: In this article, the co-extraction performance of Sr and Cs from simulated high-level liquid waste (HLLW) was studied, where the extraction solvent consists of 0.1 and 0.025 µm dicyclohexano-18-crown-6 (DCH18C-6) in n-octanol as a diluent.
Abstract: The co-extraction performance of Sr and Cs from simulated high-level liquid waste (HLLW) was studied. The extraction solvent consists of 0.1 mol/L dicyclohexano-18-crown-6 (DCH18C-6) and 0.025 mol/L 25,27-bis (isopropoxy) calix[4]-26,28-crown-6 (iPr-C[4]C-6) in n-octanol as a diluent. Testing included the extraction performance of Sr and Cs in nitric acid and in the simulated HLLW medium, and the countercurrent cascade tests. The countercurrent cascade tests included 10 stages for Sr and Cs co-extraction, 2 stages for scrubbing and 8 stages for Sr and Cs co-stripping, or 2 stages for the supplementary extraction of Cs, 4 stages for stripping Sr and 8 stages for stripping Cs were carried out on a miniature centrifugal contactor set. The removal efficiencies of Sr and Cs in the simulated HLLW were 99.0% and 99.9%, respectively, and Sr and Cs could be co-stripped together completely or individually stripped by two stripping sections. Thus, the above extractants could be used to achieve the efficiency require...
29 citations
TL;DR: In this article, the leaching behavior of actinide elements contained in the fuel debris that has arisen from the severe accident in Fukushima Daiichi Nuclear Power Station (NPS) was simulated.
Abstract: For the prediction of the leaching behavior of actinide elements contained in the fuel debris that has arisen from the severe accident in Fukushima Daiichi Nuclear Power Station (NPS), a simulated ...
27 citations
TL;DR: In this article, the authors report on the development and verification of three new resonance self-shielding methods using the new neutron transport code, STREAM, and verify the verifications were performed using the STREAM.
Abstract: This paper reports on the development and verification of three new resonance self-shielding methods. The verifications were performed using the new neutron transport code, STREAM. The new methodologies encompass the extension of energy range for resonance treatment, the development of optimum rational approximation, and the application of resonance treatment to isotopes in the cladding region. (1) The extended resonance energy range treatment has been developed to treat the resonances below 4 eV of three resonance isotopes and shows significant improvements in the accuracy of effective cross sections (XSs) in that energy range. (2) The optimum rational approximation can eliminate the geometric limitations of the conventional approach of equivalence theory and can also improve the accuracy of fuel escape probability. (3) The cladding resonance treatment method makes it possible to treat resonances in cladding material which have not been treated explicitly in the conventional methods. These three new meth...
25 citations
TL;DR: In this article, a liquid-liquid extraction system was proposed for the selective separation of lithium isotopes using ionic liquids (ILs = C8mim+PF6−, C8 mim+BF4−, and C 8mim +NTf2−) as extraction solvent.
Abstract: A novel liquid–liquid extraction system was investigated for the selective separation of lithium isotopes using ionic liquids (ILs = C8mim+PF6−, C8mim+BF4−, and C8mim+NTf2−) as extraction solvent a...
25 citations
TL;DR: In this paper, the dependence of radiation dose reduction on the sizes and materials of buildings was studied by numerical analyses using the Monte Carlo simulation code, PHITS, and the dose rates inside the buildings were calculated by simulating gamma-ray transport from radioactive cesium deposited at the ground surface.
Abstract: The dependence of radiation dose reduction on the sizes and materials of buildings was studied by numerical analyses using the Monte Carlo simulation code, PHITS. The dose rates inside the buildings were calculated by simulating gamma-ray transport from radioactive cesium deposited at the ground surface. Three building models were developed: the wooden house, the open-space concrete building, and the thin-wall building, to study the effect of building size and construction material on dose reduction inside these structures. Here the floor-area sizes of the building models were varied to clarify the influence of building configuration on dose reduction. The results demonstrated that the dose rates inside the buildings linearly decreased with increasing floor area on a logarithmic scale for all types of buildings considered. The calculated dose distribution inside a building indicated that the distance from the outer walls was a determining factor for the dose rate at each position in the building. The obta...
TL;DR: After the severe accident at the Fukushima-1 nuclear power plant, large amounts of contaminated stagnant water have accumulated in turbine buildings and their surroundings This rapid communication is called rapid communication as mentioned in this paper, which is used for communication.
Abstract: After the severe accident at the Fukushima-1 nuclear power plant, large amounts of contaminated stagnant water have accumulated in turbine buildings and their surroundings This rapid communication
TL;DR: The accident at unit 3 of the Fukushima Dai-ichi nuclear power plant was analyzed with THALES2 for the progression of severe accident coupled with Kiche for the iodine chemistry in aqueous phase as mentioned in this paper.
Abstract: The accident at unit 3 of the Fukushima Dai-ichi nuclear power plant was analyzed with THALES2 for the progression of severe accident coupled with Kiche for the iodine chemistry in aqueous phase. T...
TL;DR: In this article, a new particle collision algorithm has been carried out based on Monte Carlo approach under Lagrangian methodology, according to different collision kernel, the traveling time that a particle experiences between two neighborhood collision events is obtained in a more physical way than that in the current standard algorithm of O'Rourke.
Abstract: Particle collision is non-trivial in many processes occurring in nuclear power system. A new particle collision algorithm has been carried out based on Monte Carlo approach under Lagrangian methodology. According to different collision kernel, the traveling time that a particle experiences between two neighborhood collision events is obtained in a more physical way than that in the current standard algorithm of O'Rourke. Besides, the outcomes of particle collision are acquired by proper collision models in choosing collision pairs, which are picked up by calculating the colliding times between two particles in each pair. To evaluate the performance of this new algorithm, first, a simulation for the total number changing with time of Brownian aerosols is compared with analytical solution. And the modeling result and the analytical formulation are in excellent agreement. Second, two mutual-impingement sprays are simulated by the new collision algorithm against that of O'Rourke. Then the modeling results are...
TL;DR: In this paper, the authors derived a counter-current flow limitation (CCFL) correlation and evaluated its uncertainty for steam generator (SG) U-tubes in a pressurized water reactor (PWR).
Abstract: The purpose of this study is to derive a counter-current flow limitation (CCFL) correlation and evaluate its uncertainty for steam generator (SG) U-tubes in a pressurized water reactor (PWR). Experiments were conducted to evaluate effects of the liquid viscosity on CCFL characteristics using air–40 wt% or air–60 wt% glycerol water solution and saturated steam–water at atmospheric pressure with vertical pipes simulating the lower part of the SG U-tubes. The steam–water experiments confirmed that CCFL characteristics could be expressed in terms of the Wallis parameters (JG* and JL*) for the pipe diameters of D = 14, 20, and 27 mm. A CCFL correlation was derived using the ratio μG/μL of the viscosities of the gas and liquid phases, μG and μL, as a correction term representing effects of fluid properties, where JG*1/2(μG/μL)−0.07 was expressed by a cubic function of JL*1/2(μG/μL)0.1. In the correlation, the constant C indicating the value of JG*1/2(μG/μL)−0.07 at JL* = 0 was (1.04 ± 0.05), and this uncertaint...
TL;DR: In this paper, a new code named MOREL based on the three-dimensional diffusion steady and transient calculations was developed for the analysis of a typical molten salt reactor, including the steady characteristics, the influence of fuel circulation on the kinetic behaviors.
Abstract: The molten salt reactor is characterized by its use of the fluid-fuel, which serves both as a fuel and as a coolant simultaneously. The position of delayed neutron precursors continuously changes both in the core and in the external loop due to the fuel circulation, and the fission products are extracted by an online fuel reprocessing unit, which all lead to the modeling methods for the conventional reactors using solid fuel not applicable. This study establishes suitable calculation models for the neutronics analysis of the molten salt reactor and develops a new code named MOREL based on the three-dimensional diffusion steady and transient calculations. Some numerical tests are chosen to verify the code and the numerical results indicate that MOREL can be used for the analysis of the molten salt reactor. After verification, it is applied to analyze the characteristics of a typical molten salt reactor, including the steady characteristics, the influence of fuel circulation on the kinetic behaviors. Beside...
TL;DR: In this article, a method of identifying important fission product (FP) nuclides which are included in a simplified burnup chain is proposed, which utilizes adjoint nuclide number densities and contribution f...
Abstract: A method of identifying important fission product (FP) nuclides which are included in a simplified burnup chain is proposed. This method utilizes adjoint nuclide number densities and contribution f...
TL;DR: In this paper, the confidence interval estimation by the bootstrap method is investigated for the uncertainty quantification of neutronics calculation using the random sampling method, which is a more accurate method than the traditional stochastic sampling method.
Abstract: Confidence interval estimation by the bootstrap method is investigated for the uncertainty quantification of neutronics calculation using the random sampling method. The random sampling method is a...
TL;DR: In this article, the authors present challenges and issues in the field of nuclear power and fuel cycle physics and discuss some of the most common examples with original results with some cases of original results.
Abstract: Advanced fuel cycles and associated optimized reactor designs will require substantial improvements in key research area to meet new and more challenging requirements. The present paper reviews challenges and issues in the field of reactor and fuel cycle physics. Typical examples are discussed with, in some cases, original results.
TL;DR: Investigating how current and emerging technologies can be applied to enhance the international decommissioning strategy by focusing in particular on three-dimensional simulation, virtual reality, advanced user interfaces, mobile and wearable devices, and geographical information systems demonstrates that emerging technologies have great potential for supporting adoption of new instrumentation, improving data and knowledge management, and for communication, surveillance, and education in general.
Abstract: There is an increasing international focus on the need to optimise decommissioning strategies, driven by the anticipation of high costs and major effort for the decommissioning of nuclear facilitie...
TL;DR: In this paper, deionized water was allowed to permeate into a dried specimen of smectite (named Kunipia-F®) with different dry densities (ρd: 0.97, 1.23 and 1.88 Mg/m3) under conditions of constant temperature and volume.
Abstract: Smectite (especially, montmorillonite) is the major clay mineral constituent of bentonite, which is designed to play a key role as a buffer material in geological repositories for the final disposal of radioactive waste in Japan. It is therefore crucial to understand the hydration behavior of smectite in terms of swelling during hydration and saturation processes.Against such a background, the authors simultaneously observed behaviors of smectite swelling at the micro-level (i.e., both the generation of swelling pressure and the change of hydration state). In the experiments, deionized water was allowed to permeate into a dried specimen of smectite (named Kunipia-F®) with different dry densities (ρd: 0.97, 1.23, 1.43, 1.64 and 1.88 Mg/m3) under conditions of constant temperature and volume. The swelling pressure was measured using an in situ uniaxial consolidation apparatus during the water feeding process. Changes in local hydration states (i.e., one-molecular-layer hydration states to three-molecular-la...
TL;DR: In this article, a natural circulation evaluation methodology has been developed to ensure the safety of a sodium-cooled fast reactor (SFR) of 1500 MW adopting the natural circulation decay heat removal system (NC-DHRS).
Abstract: A natural circulation evaluation methodology has been developed to ensure the safety of a sodium-cooled fast reactor (SFR) of 1500 MW adopting the natural circulation decay heat removal system (NC-DHRS). The methodology consists of a one-dimensional safety analysis which can evaluate the core hot spot temperature taking into account the temperature flattening effect in the core, a three-dimensional fluid flow analysis which can evaluate the thermal-hydraulics for local convections and thermal stratifications in the primary system and DHRS, and a statistical safety evaluation method for the hot spot temperature in the core. The safety analysis method and the three-dimensional analysis method have been validated using results of a 1/10 scaled water test simulating the primary system of the SFR and a sodium test simulating a part of the primary system and the DHRS with about a 1/7 scale, and the applicability of the safety analysis for the SFR has been confirmed by comparing with the three-dimensional analys...
TL;DR: In this paper, the photonuclear reaction model in the particle and heavy ion transport code system (PHITS) code is improved for incident photon energies below 140 MeV Japanese Evaluated Nuclear Data Library (JENDL/PD-2004) is adopted to determine the total reaction cross section.
Abstract: The photonuclear reaction model in the particle and heavy ion transport code system (PHITS) code is improved for incident photon energies below 140 MeV Japanese Evaluated Nuclear Data Library (JENDL) Photonuclear Data File 2004 (JENDL/PD-2004) is adopted to determine the total reaction cross section The statistical decay model after excitation of the nucleus in PHITS is improved by modifying the decay widths for light nuclei under the isospin selection rule to reasonably reproduce the proton and neutron emission in the de-excitation process The quasideuteron disintegration process is newly introduced into PHITS to handle the photonuclear reaction up to 140 MeV of incident photon energy The accuracy of the improvements was verified by comparison with the experimental literature data The improved PHITS can contribute to various practical applications such as neutron dose estimation in X-ray therapy
TL;DR: In this article, the applicable range of the intranuclear cascade model was successfully extended to lower incident energy (p, p′x) reactions by introducing trajectory deflections and low energy-loss process due to collective excitations.
Abstract: In our previous study, the applicable range of the intranuclear cascade model was successfully extended to lower incident energy (p, p′x) reactions by introducing trajectory deflections and low-energy-loss process due to collective excitations. However, the model's validity was confirmed only for a 56Fe target. In the present work we widen the applicable range of masses of the target nucleus. First, we derive an expression for the response function, which gives the probability of collective excitation strengths, to fit the distorted-wave Born approximation results as a function of the target mass number and the beam energy. Second, the barrier transmission coefficient was investigated. An expression with a modified Gamow penetration factor was chosen from four phenomenological forms of one-dimensional barrier transmission coefficients. Calculations with the proposed model followed by a generalized evaporation model were carried out for double-differential cross sections of (p, p′x) reactions at 30–60 MeV....
TL;DR: The variations in the nuclear waste management performance have been assessed for 40 fuel-cycle examples with the calculation of the mass, activity, toxicity and decay heat of spent nuclear fuel as discussed by the authors.
Abstract: The variations in the nuclear waste management performance have been assessed for 40 fuel-cycle examples with the calculation of the mass, activity, toxicity and decay heat of spent nuclear fuel an...
TL;DR: In this paper, chemical reactions between stainless steel and boron carbide were investigated using the materials applied for control rods in BWRs in Japan, specifically 304L-type Stainless steel and granular bor...
Abstract: Chemical reactions between stainless steel and boron carbide were investigated using the materials applied for control rods in BWRs in Japan, specifically 304L-type stainless steel and granular bor...
TL;DR: In this paper, the dissolution behavior of Sr-II to the mixed seawater was experimentally investigated by the solubility measurement of Sr(II) under several solution conditions (mixing degree of seawater, pH, strontium concentration and temperature) and the microscopic analysis of the formed solid phase.
Abstract: For the better understanding of chemical behavior of Sr-90 released from the damaged reactor cores of Fukushima Daiichi nuclear power station into the seawater system, the dissolution behavior of Sr(II) to the mixed seawater was experimentally investigated by the solubility measurement of Sr(II) under several solution conditions (mixing degree of seawater, pH, strontium concentration and temperature) and the microscopic analysis of the formed solid phase. The obtained results of the experiment were compared with thermodynamic equilibrium calculations for an interpretation of chemistry of Sr(II) in the targeted solution system. It was revealed that the Sr solubility became higher than the reported value in generic seawater system, while the solubility limiting solid was identified as SrSO4 which corresponded with the result of equilibrium calculation. Furthermore, under the unsaturated condition, about 6% of Sr(II) interacted with natural nano-size colloids existing in the Fukushima seawater and was captur...
TL;DR: In this article, biaxial stress was applied to Zircaloy-4 cladding by pressurizing Ar gas, and the results showed that the ductility decreases with an increase in radial hydride quantity.
Abstract: A hydride reorientation can deteriorate the mechanical ductility of spent fuel cladding and make it more susceptible to failure. Therefore, an evaluation of the reorientation under dry storage conditions and their effects on the cladding ductility are critical issues in terms of the regulation criteria. In this work, biaxial stress was applied to Zircaloy-4 cladding by pressurizing Ar gas. The study showed that the hydride reorientation can occur at around 60 and 80 MPa at 400 and 300 °C, respectively. The ring compression test at room temperature showed that the ductility decreases with an increase in radial hydride quantity: Fl(45) and radial hydride continuity factor. In addition, a significant hydride reorientation can occur at high temperature conditions even if the hoop stress is equal to or less than 90 MPa which can bring a significant ductility degradation.
TL;DR: The effects of air on the corrosion of Hastelloy-N alloys in molten salt coolant containing fission product elements were investigated to determine the safety of structural materials in high-temperatures as mentioned in this paper.
Abstract: The effects of air on the corrosion of Hastelloy-N alloys in molten salt coolant containing fission product elements were investigated to determine the safety of structural materials in high-temper...
TL;DR: In this article, the measured dynamic structure factors S(q, ω) have been reduced, normalized and transformed into the S(α, β) formalism, where α and β stand for the unitless momentum and energy transfers, respectively.
Abstract: In this study, we report on recent neutron inelastic scattering experiments performed at the Institut Laue-Langevin (ILL) for H2O and D2O. The measured dynamic structure factors S(q, ω) have been reduced, normalised and transformed into the S(α, β) formalism, where α and β stand for the unit-less momentum and energy transfers, respectively. The measurements were complemented with molecular dynamics simulations. After processing with NJOY, new water neutron scattering cross-sections have been generated for use with e.g. the Monte Carlo N-Particle (MCNP) software in view to improve the accuracy of the nuclear facility models. As an example, we present improved accuracy calculations for the safety rod insertion impact on the criticality factor keff for the ILL high flux research reactor.