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The effect of hydrogen and oxygen contents on hydride reorientations of zirconium alloy cladding tubes
The lower hydrogen contents and the slower cooling rate generated a larger fraction of radial hydrides, a longer radial hydride length, and a lower ultimate tensile strength and plastic elongation. In addition, the oxidized specimens generated a smaller fraction of radial hydrides and a lower ultimate tensile strength and plastic elongation than the nonoxidized specimens.
7/4/2019 6:30:49 AM +00:00
The adaptation method in the monte carlo simulation for computed tomography
The patient dose incurred from diagnostic procedures during advanced radiotherapy has become an important issue. Many researchers in medical physics are using computational simulations to calculate complex parameters in experiments. However, extended computation times make it difficult for personal computers to run the conventional Monte Carlo method to simulate radiological images with high-flux photons such as images produced by computed tomography (CT).
7/4/2019 6:30:33 AM +00:00
Terrapower, LLC traveling wave reactor development program overview
The fast neutron spectrum allows up to a ~30-fold gain in fuel utilization efficiency when compared to conventional light water reactors utilizing enriched fuel. When compared to other fast reactors, TWRs represent the lowest cost alternative to enjoy the energy security benefits of an advanced nuclear fuel cycle without the associated proliferation concerns of chemical reprocessing. On a country level, this represents a significant savings in the energy generation infrastructure for several reasons 1) no reprocessing plants need to be built, 2) a reduced number of enrichment plants need to be built, 3) reduced waste production results in a lower repository capacity requirement and reduced waste transportation costs and 4) less uranium ore needs to be mined or purchased since natural or depleted uranium can be used directly as fuel.
7/4/2019 6:30:12 AM +00:00
Superheated water - cooled small modular underwater reactor concept
In this study, new cladding material to withstand high temperature steam in addition to the fuel mechanical and safety behavior is investigated. The steam temperature was found to depend on the thermal and mechanical characteristics of the fuel. The SWR showed a very different transient behavior compared with a boiling water reactor.
7/4/2019 6:29:53 AM +00:00
Study on the structure optimization and the operation scheme design of a double tube once through steam generator
A double-tube once-through steam generator (DOTSG) consisting of an outer straight tube and an inner helical tube is studied in this work. First, the structure of the DOTSG is optimized by considering two different objective functions. The tube length and the total pressure drop are considered as the first and second objective functions, respectively. Because the DOTSG is divided into the subcooled, boiling, and superheated sections according to the different secondary fluid states, the pitches in the three sections are defined as the optimization variables.
7/4/2019 6:29:35 AM +00:00
Study on the recycling of nuclear graphite after micro-oxidation
In this paper, a feasible strategy for the recycling of nuclear graphite is reported, based on the formation mechanism and the removal of carbon-14 by micro-oxidation. We investigated whether ground micro-oxidation graphite could be used as a filler to make new recycled graphite and which graphite/pitch coke ratio will give the recycled graphite outstanding properties (e.g., apparent density, flexural strength, compressive strength, and tensile strength).
7/4/2019 6:29:18 AM +00:00
Study on the effect of the self attenuation coefficient on a ray detector efficiency calculated at low and high energy regions
The present work used the efficiency transfer method used to calculate the full energy peak efficiency (FEPE) curves of the (2*2 & 3*3) NaI (Tl) detectors based on the effective solid angle subtended between the source and the detector. The study covered the effect of the self attenuation coefficient of the source matrix (with a radius greater than the detector's radius) on the detector efficiency. 152 An Eu aqueous radioactive source covering the energy range from 121.78 keV up to 1408.01 keV was used. In this study an empirical formula was deduced to calculate the difference between the measured and the calculated efficiencies [without self attenuation] at low and high energy regions.
7/4/2019 6:29:01 AM +00:00
Study on heat transfer characteristics of the one side-heated vertical channel with inserted porous materials applied as a vessel cooling system
In the very high temperature reactor (VHTR), which is a next generation nuclear reactor system, ceramics are used as a fuel coating material and graphite is used as a core structural material. Even if a depressurization accident occurs and the reactor power goes up instantly, the temperature of the core will change only slowly. This is because the thermal capacity of the core is so high.
7/4/2019 6:28:43 AM +00:00
Study of the effect of (U0.8Pu0.2)O2 uraniume plutonium mixed fuel fission products on a living organism
The article describes the results of experiments conducted on pigs to determine the effect of plutonium, which is the most radiotoxic and highly active element in the range of mixed fuel (U0.8Pu0.2)O2 fission products, on living organisms. The results will allow empirical prediction of the emergency plutonium radiation dose for various organs and tissues of humans in case of an accident in a reactor running on mixed fuel (U0.8Pu0.2)O2.
7/4/2019 6:28:24 AM +00:00
Study of lower hybrid current drive for the demonstration reactor
Steady-state operation of a fusion power plant requires external current drive to minimize the power requirements, and a high fraction of bootstrap current is required. One of the external sources for current drive is lower hybrid current drive, which has been widely applied in many tokamaks. Here, using lower hybrid simulation code, we calculate electron distribution function, electron currents and phase velocity changes for two options of demonstration reactor at the launched lower hybrid wave frequency 5 GHz.
7/4/2019 6:28:08 AM +00:00
Study of core support barrel vibration monitoring using ex core neutron noise analysis and fuzzy logic algorithm
A distinct pattern of phase differences was observed for each of the vibration models. The developed fuzzy logic module demonstrated successful recognition of the vibration frequencies, modes, orders, directions, and phase differences within 0.4 ms for the beam and shell mode vibrations
7/4/2019 6:27:51 AM +00:00
Study of a betavoltaic battery using electroplated nickel 63 on nickel foil as a power source
A betavoltaic battery was prepared using radioactive 63Ni attached to a three-dimensional single trenched PeN absorber. The optimum thickness of a 63Ni layer was determined to be approximately 2 mm, considering the minimum self-shielding effect of beta particles. Electroplating of radioactive 63Ni on a nickel (Ni) foil was carried out at a current density of 20 mA/cm2 .
7/4/2019 6:27:31 AM +00:00
Structural assessment of reactor pressure vessel under multi layered corium formation conditions
In the present study, several key factors related to molten corium behaviors and thermal characteristics were examined under multi-layered corium formation conditions. Thereafter, systematic finite element analyses and subsequent damage evaluation with varying parameters were performed on a representative reactor pressure vessel (RPV) to figure out the possibility of high temperature induced failures.
7/4/2019 6:27:14 AM +00:00
Strain based plastic instability acceptance criteria for ferritic steel safety class 1 nuclear components under level d service loads
This paper proposes strain-based acceptance criteria for assessing plastic instability of the safety class 1 nuclear components made of ferritic steel during level D service loads. The strain-based criteria were proposed with two approaches: (1) a section average approach and (2) a critical location approach. Both approaches were based on the damage initiation point corresponding to the maximum load-carrying capability point instead of the fracture point via tensile tests and finite element analysis (FEA) for the notched specimen under uni-axial tensile loading.
7/4/2019 6:26:58 AM +00:00
Steam generator tube integrity analysis of a total loss of all heat sinks accident for wolsong NPP unit 1
This paper describes the analysis of DCRV discharge capacity and the SG tube integrity under a total loss of all heat sink using the CATHENA code. It was found that the DCRV's discharge capacity is enough to protect the overpressure in the PHTS, and the SG tube integrity is maintained in a total loss of all heat accident.
7/4/2019 6:26:42 AM +00:00
Steady - and transient state analyses of fully ceramic microencapsulated fuel with randomly dispersed tristructural isotropic particles via two temperature homogenized modeldii: Applications by coupling with coredax
In Part I of this paper, the two-temperature homogenized model for the fully ceramic microencapsulated fuel, in which tristructural isotropic particles are randomly dispersed in a fine lattice stochastic structure, was discussed. In this model, the fuel-kernel and silicon carbide matrix temperatures are distinguished. Moreover, the obtained temperature profiles are more realistic than those obtained using other models. Using the temperature-dependent thermal conductivities of uranium nitride and the silicon carbide matrix, temperaturedependent homogenized parameters were obtained.
7/4/2019 6:26:20 AM +00:00
Steady - and transient state analyses of fully ceramic microencapsulated fuel with randomly dispersed tristructural isotropic particles via two temperature homogenized modeldi: theory and method
For a fuel element with such high heterogeneity, we have proposed a two-temperature homogenized model using the particle transport Monte Carlo method for the heat conduction problem. This model distinguishes between fuel-kernel and SiC matrix temperatures. Moreover, the obtained temperature profiles are more realistic than those of other models.
7/4/2019 6:26:00 AM +00:00
Status of the astrid core at the end of the preconceptual design phase 1
Within the framework of the ASTRID project, core design studies are being conducted by the CEA with support from AREVA and EDF. The pre-conceptual design studies are being conducted in accordance with the GEN IV reactor objectives, particularly in terms of improving safety. This involves limiting the consequences of 1) a hypothetical control rod withdrawal accident (by minimizing the core reactivity loss during the irradiation cycle), and 2) an hypothetical loss-of-flow accident (by reducing the sodium void worth).
7/4/2019 6:25:45 AM +00:00
Srf linac for future extension of the pefp
A study on the superconducting RF linac is underway in order to increase the beam energy up to 1 GeV by extending the Proton Engineering Frontier Project (PEFP) 100-MeV linac. The operating frequency of the PEFP superconducting linac (SCL) is 700 MHz, which is determined by the fact that the frequency of the existing normal conducting linac is 350 MHz.
7/4/2019 6:25:24 AM +00:00
Spectrum weighted responses of several detectors in mixed fields of fast and thermal neutrons
The spectrum weighted responses of various detectors were calculated to provide guidance on the proper selection and use of survey instruments on the basis of their energy response characteristics on the neutron fields. To yield the spectrum weighted response, the detector response functions of 17 neutron-measuring devices were numerically folded with each of the produced calibration neutron spectra through the in-house developed software ‘K-SWR’.
7/4/2019 6:25:09 AM +00:00
Spectrometry analysis of fumes of mixed nuclear fuel (U0.8Pu0.2)O2e samples heated up to 2,000с and evaluation of accidental irradiation of living organisms by plutonium as the most radiotoxic fission product of mixed nuclear fuel
The main results of the research described are the following: (1) following the research on the influence of mixed fuel fission products (radioactive isotopes being formed during reactor operation as a result of nuclear decay of elements included into the fuel composition) on living organisms, the authors determined the quantities of plutonium dioxide (РuO2) that penetrated into blood and lay in the pulmonary region, liver, skeleton and other tissues.
7/4/2019 6:24:51 AM +00:00
Single bubble dynamic behavior in al2o3 h2o nanofluid on downward facing heating surface
In this study, the moving particle semi-implicit method-meshless advection using flow-directional local grid method is used to simulate the bubble growth, departure, and sliding on the downward-facing heating surface in pure water and nanofluid (1.0 vol.% Al2O3/H2O) flow boiling processes; additionally, the bubble critical departure angle and sliding characteristics and their influence are also investigated.
7/4/2019 6:24:31 AM +00:00
Simulation of containment pressurization in a large break-loss of coolant accident using singlecell and multicell models and contain code
In addition, spray operation has been added to this model. In the second step, the single-cell model has been developed into a multicell model to consider the effects of the nodalization and spatial location of cells in the containment pressurization in comparison with the single-cell model.
7/4/2019 6:24:17 AM +00:00
Simulation based investigation of focusing phased array ultrasound in dissimilar metal welds
Flaws at dissimilar metal welds (DMWs), such as reactor coolant systems components, Control Rod Drive Mechanism (CRDM), Bottom Mounted Instrumentation (BMI) etc., in nuclear power plants have been found. Notably, primary water stress corrosion cracking (PWSCC) in the DMWs could cause significant reliability problems at nuclear power plants. Therefore, phased array ultrasound is widely used for inspecting surface break cracks and stress corrosion cracks in DMWs.
7/4/2019 6:24:05 AM +00:00
Shielding analysis of dual purpose casks for spent nuclear fuel under normal storage conditions
The shielding analysis results for the 2x10 cask array showed exponential decrease with distance off the sources. The controlled area boundary was calculated to be approximately 280m from the array, with a dose rate of 25mrem/yr. Actual dose rates within the controlled area boundary will be lower than 25mrem/yr, due to the decay of radioactivity of spent fuel in storage.
7/4/2019 6:23:48 AM +00:00
Severe accident issues raised by the fukushima accident and improvements suggested
This paper revisits the Fukushima accident to draw lessons in the aspect of nuclear safety considering the fact that the Fukushima accident resulted in core damage for three nuclear power plants simultaneously and that there is a high possibility of a failure of the integrity of reactor vessel and primary containment vessel.
7/4/2019 6:23:32 AM +00:00
Separative power of an optimised concurrent gas centrifuge
The problem of separation of isotopes in a concurrent gas centrifuge is solved analytically for an arbitrary binary mixture of isotopes. The separative power of the optimised concurrent gas centrifuges for the uranium isotopes equals to dU ¼ 12.7 (V/700 m/s)2 (300 K/T)(L/1 m) kg$SWU/yr, where L and V are the length and linear velocity of the rotor of the gas centrifuge and T is the temperature. This equation agrees well with the empirically determined separative power of optimised counter-current gas centrifuges.
7/4/2019 6:23:17 AM +00:00
Separation of strontium and cesium from ternary and quaternary lithium chloride - potassium chloride salts via melt crystallization
In the quaternary experiments, separation of Cs and Sr was nearly identical at the slower rates; however, as the growth rate increased, SrCl2 separated more easily than CsCl. The quaternary results show less separation and rate dependence than in both ternary cases. As an estimated result, only 51% of the total salt could be recycled per batch.
7/4/2019 6:23:01 AM +00:00
Separation of CsCl from LiCl-CsCl molten salt by cold finger melt crystallization
This study provides a fundamental understanding of a cold finger melt crystallization technique by exploring the heat and mass transfer processes of cold finger separation. A series of experiments were performed using a simplified LiCl-CsCl system by varying initial CsCl concentrations (1, 3, 5, and 7.5 wt%), cold finger cooling rates (7.4, 9.8, 12.3, and 14.9 L/min), and separation times (5, 10, 15, and 30 min).
7/4/2019 6:22:43 AM +00:00
Sensitivity analysis of core neutronic parameters in electron accelerator driven subcritical advanced liquid metal reactor
In addition, sensitivity of the core neutronic parameters in accelerator-driven subcritical advanced liquid metal reactors, such as electron beam energy (Ee) and source multiplication coefficient (ks), has been investigated. A Monte Carlo code (MCNPX_2.6) has been used to calculate neutronic parameters such as effective multiplication coefficient (keff), net neutron multiplication (M), neutron yield (Yn/ e), energy constant gain (G0), energy gain (G), importance of neutron source (4* ), axial and radial distributions of neutron flux.
7/4/2019 6:22:21 AM +00:00