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Real-time estimation of break sizes during LOCA in nuclear power plants using NARX neural network
This paper deals with break size estimation of loss of coolant accidents (LOCA) using a nonlinear autoregressive with exogenous inputs (NARX) neural network. Previous studies used static approaches, requiring time-integrated parameters and independent firing algorithms.
7/3/2019 4:19:29 PM +00:00
Stratified steam explosion energetics
In this study, we review previous stratified steam explosion experiments as well as recent experiments performed at the KTH in Sweden. While experiments with prototypic reactor materials are minimal, we do note that generally the energetics is limited for the stratified mode of contact. When the fuel mass involved in a steam explosion in a stratified geometry is compared to a pool geometry based on geometrical aspects, one can conclude that there is a very limited set of conditions
7/3/2019 4:19:10 PM +00:00
Thermal-hydraulic study of air-cooled passive decay heat removal system for APRþ under extended station blackout
The simulation contains two phases based on water depletion: the early phase and the late phase. In the early phase, the volume of water in PCCT was determined to avoid the water depletion in three days after shutdown. In the late phase, when the number of the HXs is greater than 4089 per PCCT, the MARS simulation confirmed the long-term cooling by air is possible under extended Station Blackout (SBO).
7/3/2019 4:18:48 PM +00:00
Design and test result of a superconducting double-spoke cavity
In this paper, the RF design, the mechanical design and fabrication considerations of the bare cavity will be described in detail. After Buffered Chemical Polishing and High Pressure Rinsing, one of the prototype cavities was installed into the Vertical Test Stand for high gradient RF testing at 4.2 K.
7/3/2019 4:18:24 PM +00:00
A methodology for the identification of the postulated initiating events of the Molten Salt Fast Reactor
The Molten Salt Fast Reactor (MSFR) with its liquid circulating fuel and its fast neutron spectrum calls for a new safety approach including technological neutral methodologies and analysis tools adapted to early design phases. In the frame of the Horizon2020 program SAMOFAR (Safety Assessment of the Molten Salt Fast Reactor) a safety approach suitable for Molten Salt Reactors is being developed and applied to the MSFR.
7/3/2019 4:18:07 PM +00:00
Positive or negative? Public perceptions of nuclear energy in South Korea: Evidence from Big Data
This study suggests a big data analyzing method with K-LIWC (Korean-Linguistic Inquiry and Word Count), sentiment and query analysis methods, and investigates public attitudes, positive and negative emotional statements about nuclear energy with the collected data sets of wellknown social media and network services in Korea over time.
7/3/2019 4:17:49 PM +00:00
Numerical simulation of complex hexagonal structures to predict drop behavior under submerged and fluid flow condition
This study simulated a control rod assembly (CRA), which is a part of reactor shutdown systems, in immersed and fluid flow conditions. The CRA was inserted into the reactor core within a predetermined time limit under normal and abnormal operating conditions, and the CRA (which consists of complex geometric shapes) drop behavior is numerically modeled for simulation.
7/3/2019 4:17:26 PM +00:00
Evaluation of nuclear material accountability by the probability of detection for loss of Pu (LOPu) scenarios in pyroprocessing
The analysis is carried out by the hypothesis testing and the event tree method. The probability of detection for diversion of 8 kg Pu is found to be less than 95% if a large size granule consisting of small size particles gets sampled for measurements. To increase the probability of detection more than 95%, first, a new Material Balance Area (MBA) structure consisting of more number of Key Measurement Points (KMPs) is designed.
7/3/2019 4:17:09 PM +00:00
A method for properties evaluation of activated charcoal sorbents in iodine capture under dynamic conditions
The sorption capacity index a is proposed as a criterion parameter for assessing the quality of impregnated activated charcoals. It was found that this parameter does not depend on the dynamic conditions during the sorbent test. It was shown that values of the sorption capacity index allow to recommend iodine sorbents for industrial gas cleaning processes.
7/3/2019 4:16:51 PM +00:00
Thermal hydraulic analysis of core flow bypass in a typical research reactor
The main objective of nuclear reactor safety is to maintain the nuclear fuel in a thermally safe condition with enough safety margins during normal operation and anticipated operational occurrences. In this research, core flow bypass is studied under the conditions of the unavailability of safety systems. As core bypass occurs, the core flow rate is assumed to decrease exponentially with a time constant of 25 s to new steady state values of 20, 40, 60, and 80% of the nominal core flow rate.
7/3/2019 4:16:36 PM +00:00
Corrosion and mechanical properties of hot-rolled 0.5%Gd-0.8%Bstainless steels in a simulated nuclear waste treatment solution
The austenite and ferrite phases of the 0.5%Gd-0.8%B-stainless steels are about 88:12. The average austenite and ferrite grain size of the plane normal to rolling, transverse and normal directions of the hot rolled specimens are about 5.08, 8.94, 19.35, 23.29, 26.00 and 18.11 [mm], respectively. The average micro-hardness of the as-cast specimen is 200.4 Hv, whereas, that of the hot-rolled specimen are 220.1, 204.7 and 203.5 [Hv] for the plane normal to RD, TD and ND, respectively.
7/3/2019 4:16:10 PM +00:00
Improvement and verification of the DeCART code for HTGR core physics analysis
This paper presents the recent improvements in the DeCART code for HTGR analysis. A new 190-group DeCART cross-section library based on ENDF/B-VII.0 was generated using the KAERI library processing system for HTGR. Two methods for the eigen-mode adjoint flux calculation were implemented. An azimuthal angle discretization method based on the Gaussian quadrature was implemented to reduce the error from the azimuthal angle discretization.
7/3/2019 4:15:49 PM +00:00
Thermal neutron albedo and flux for different geometries neutron guide
This paper presents a study on thermal neutron reflection properties of neutron guide for cylinder, spindle, elliptic and parabolic geometries using 241Am-Be neutron source (5.2 Ci) and BF3 detector, whereas neutron guide is important instrument for transportation of neutrons. To this goal, the required inner and outer radii of neutron guide have been calculated to achieve the highest guided thermal neutron flux based on MCNPX Monte Carlo code.
7/3/2019 4:15:29 PM +00:00
Performance evaluation of noise reduction algorithm with median filter using improved thresholding method in pixelated semiconductor gamma camera system: A numerical simulation study
To improve the noise characteristics, software-based noise reduction algorithms are widely used in cadmium zinc telluride (CZT) pixelated semiconductor gamma camera system. The purpose of this study was to develop an improved median filtering algorithm using a thresholding method for noise reduction in a CZT pixelated semiconductor gamma camera system.
7/3/2019 4:15:09 PM +00:00
Research on the structure design of the LBE reactor coolant pump in the lead base heap
This study mainly focuses on the structural design optimization of the 4th-generation reactor coolant pump, including analysis of external characteristics, inner flow, and transient characteristic. It was found that: the reactor coolant pump with a central symmetrical dual-outlet volute structure has better radialdirection balance, the pump without guide vane has better hydraulic performance, and the pump with guide vanes has worse torsional vibration and pressure pulsation.
7/3/2019 4:14:51 PM +00:00
Behavior characteristics of hydrogen and its isotope in molten salt of LiF-NaF-KF (FLiNaK)
The results showed the behaviors of deuterium were consistence with the behaviors of hydrogen in FLiNaK. The difference between hydrogen and deuterium has not been observed upon the experimental research of the behavior characteristics of hydrogen and deuterium in FLiNaK, which suggested the results obtained here might apply equally to the behavior characteristics of tritium in FLiNaK.
7/3/2019 4:14:32 PM +00:00
Human and organizational factors for multi-unit probabilistic safety assessment: Identification and characterization for the Korean case
This study identifies and categorizes the human and organizational factors relevant to a multi-unit incident scenario of NPPs based on a review of relevant literature. These factors are then analyzed to ascertain all possible unit-tounit interactions that need to be considered in the multi-unit HRA and the pattern of interactions.
7/3/2019 4:14:10 PM +00:00
Logic tree approach for probabilistic typhoon wind hazard assessment
The wind speeds of the simulated typhoons and the probable maximum wind speeds are estimated using Monte Carlo simulations, and wind hazard curves are derived as a function of the annual exceedance probability or return period. A logic tree decreases the epistemic uncertainty included in the wind intensity models and provides reasonably acceptable wind speeds.
7/3/2019 4:13:51 PM +00:00
Transient safety analysis of M2 LFR-1000 reactor using ATHLET
The results indicate that the M2 LFR is safe enough under these three transients due to the good inherent safety features of the reactor, without human intervention, the reactor will reach a new steady state under UTOP condition.
7/3/2019 4:13:31 PM +00:00
Simulation of impact toughness with the effect of temperature and irradiation in steels
. The effect of temperature on impact toughness was analyzed by the model and the trend of the simulation results was basicly consistent with the previous experimental results of CLAM steels. The load-displacement curve was simulated to express the low temperature ductile-brittle transition. The effect of grain size and inclusion was analyzed by the model, which was consistent with classical experiment results. The transgranular-intergranular transformation in brittle materials was also simulated.
7/3/2019 4:13:15 PM +00:00
Simulation and design of individual neutron dosimeter and optimization of energy response using an array of semiconductor sensors
The performance of the simulation scheme has been compared with the commercial and laboratory samples in the world. Due to the deviation of all dosimeters with a flat energy response, in this paper, has been used an idea of one semi-conductor sensor to have the flat energy-response in the entire neutron energy range. Finally, by analyzing of the sensors data as arrays for the first time, we have reached a nearly flat and acceptable energy-response.
7/3/2019 4:12:57 PM +00:00
Study of n/g discrimination using 3 He proportional chamber in high gamma-ray fields
In this study, an improved algorithm for n/g discrimination using a parameter, which is the ratio of the rise time to the pulse height, is proposed. The n/g discrimination performance of the algorithm is evaluated by applying it to 252Cf neutron signal separation from various gamma-ray exposure rate levels ranging 0.1e5 R/h. The performance is compared to that of the conventional pulse-height analysis method in terms of the gamma elimination ratio.
7/3/2019 4:12:38 PM +00:00
The design and fabrication of 81.25 MHz RFQ for Low Energy Accelerator Facility
To provide high shunt impendence with low power losses, an 81.25 MHz continuous wave (CW) radio frequency quadrupole (RFQ) accelerator has been designed and machined as parts of the Low Energy Accelerator Facility (LEAF). In this paper, the mechanical structure and the main processing technology of the RFQ cavities are described according to the physical and geometric parameters requirements of the RFQ. The fabrication of the RFQ has been completed and the test results agree well with the design requirements. The RFQ accelerator will work in Institute of Modern Physics, Chinese Academy of Sciences in 2018.
7/3/2019 4:12:17 PM +00:00
A leak detection and 3D source localization method on a plant piping system by using multiple cameras
In this paper, a method using multiple cameras to detect leakage and estimate the three-dimensional coordinates of the leakage location is presented. Leakage is detected by each camera using MADI(Moving Average Differential Image) and histogram analysis. The twodimensional leakage location is estimated using the detected leakage area.
7/3/2019 4:11:58 PM +00:00
Dropwise condensation induced on chromium ion implanted aluminum surface
Aluminum substrates are irradiated with chromium ions and the steam condensation heat transfer performance on these surfaces is examined. Filmwise condensation is induced on the surface of aluminum specimens irradiated with chromium ion dose of less than 1016 ions/cm2 while dropwise condensation occurs on the specimens irradiated with chromium ion dose of 5 1016 ions/cm2 in the range of ion energy from 70 to 100 keV.
7/3/2019 4:11:39 PM +00:00
Mitigation of high energy arcing faults in nuclear power plant medium voltage switchgear
A high energy arcing fault event occurred in the medium-voltage (13.8 kV and 4.16 kV) metalclad switchgears in a nuclear power plant not only affecting switchgear but also connected equipment due to the arc energy. The high energy arcing fault also causes a fire that influences the safety function of the unit. Therefore, from the safety point of view, it is necessary to evaluate the influences of high energy arcing fault events on the safety functions of nuclear power plants.
7/3/2019 4:11:21 PM +00:00
Architectural model driven dependability analysis of computer based safety system in nuclear power plant
The most important non-functional requirements for dependability of any Embedded Real-Time Safety Systems are safety, availability and reliability requirements. System architecture plays the primary role in achieving these requirements. Compliance with these non-functional requirements should be ensured early in the development cycle with appropriate considerations during architectural design. In this paper, we present an application of system architecture modeling for quantitative assessment of system dependability.
7/3/2019 4:10:57 PM +00:00
Contribution of production and loss terms of fission products on incontainment activity under severe accident condition for VVER-1000
The purpose of this paper is to study the source term behavior after severe accidents by using a semikinetic model for simulation and calculation of in-containment activity. The reactor containment specification and the safety features of the containment under different accident conditions play a great role in evaluating the in-containment activity.
7/3/2019 4:10:35 PM +00:00
Sensitivity analysis of thermal-hydraulic parameters to study the corrosion intensity in nuclear power plant steam generators
The failure of steam generators (SGs) due to corrosion is one of the most important problems in power plants. Impurities usually accumulate in the hot sides of SG and form deposits on the SG surfaces. In this paper, the sensitivity analysis of the accumulation of water impurities in the heat exchangers of nuclear power plants is presented.
7/3/2019 4:10:21 PM +00:00
Influences of heating processes on properties and microstructure of porous CeO2 beads as a surrogate for nuclear fuels fabricated by a microfluidic sol-gel process
This study concerns the effect of heating processes on properties and microstructure of the fuel particles. The uniform gel precursor beads were synthesized by a microfluidic sol-gel process and then the porous CeO2 microspheres, as a surrogate for the ceramic nuclear fuel particles, were obtained by heating treatment of the gel precursors.
7/3/2019 4:10:03 PM +00:00