Tài liệu miễn phí Năng lượng
Download Tài liệu học tập miễn phí Năng lượng
Uncertainty analysis of ROSA/LSTF test by RELAP5 code and PKL counterpart test concerning PWR hot leg break LOCAs
In the LSTF test, core uncovery started simultaneously with liquid level drop in crossover leg downflow-side before loop seal clearing, and water remaining occurred on the upper core plate in the upper plenum. Results of the uncertainty analysis with RELAP5/MOD3.3 code clarified the influences of the combination of multiple uncertain parameters on peak cladding temperature within the defined uncertain ranges.
7/4/2019 3:45:07 AM +00:00
Comparison of proliferation resistance among natural uranium, thoriumeuranium, and thoriumeplutonium fuels used in CANada Deuterium Uranium in deep geological repository by combining multiattribute utility analysis with transport model
The proliferation resistance (PR) of Th/U and Th/Pu fuels used in CANada Deuterium Uranium for the deep geological repository was assessed by combining the multiattribute utility analysis proposed by Chirayath et al., 2015 [1] with the transport model of radionuclides in the repository and comparing with that of the used natural U fuel case. It was found that there was no significant advantage for Th/U and Th/ Pu fuels from the viewpoint of the PR in the repository.
7/4/2019 3:44:48 AM +00:00
Development of Cr cold sprayecoated fuel cladding with enhanced accident tolerance
Accident-tolerant fuels (ATFs) are currently of high interest to researchers in the nuclear industry and in governmental and international organizations. One widely studied accident-tolerant fuel concept is multilayer cladding (also known as coated cladding). This concept is based on a traditional Zr-based alloy (Zircaloy-4, M5, E110, ZIRLO etc.) serving as a substrate. Different protective materials are applied to the substrate surface by various techniques, thus enhancing the accident tolerance of the fuel. This study focuses on the results of testing of Zircaloy-4 coated with pure chromium metal using the cold spray (CS) technique.
7/4/2019 3:44:27 AM +00:00
Simulation of reactivity-initiated accident transients on UO2-M5® fuel rods with ALCYONE V1.4 fuel performance code
This article first presents ALCYONE V1.4 RIA-related features and modeling. It especially focuses on recent developments dedicated on the one hand to nonsteady water heat and mass transport and on the other hand to the modeling of grain boundary cracking-induced fission gas release and swelling. This article then compares some simulations of RIA transients performed on UO2-M5® fuel rods in flowing sodium or stagnant water coolant conditions to the relevant experimental results gained from tests performed in either the French CABRI or the Japanese NSRR nuclear transient reactor facilities.
7/4/2019 3:44:08 AM +00:00
Semiempirical model for wet scrubbing of bubble rising in liquid pool of sodium-cooled fast reactor
The scrubbing of aerosol and vapor are modeled based on deposition mechanisms and Fick's law of diffusion, respectively. Studies were performed to determine the effect of various key parameters on wet scrubbing. It is observed that for higher vapor diffusion coefficient in gas bubble, the scrubbing efficiency is higher. For aerosols, the cut-off size above which the scrubbing efficiency becomes significant was also determined.
7/4/2019 3:43:52 AM +00:00
A scintillation detector configuration for pulse shape analysis
This paper presents a neutron detector configuration using EJ-301 scintillation liquid, a R9420 photomultiplier and a homemade preamplifier. The detector qualities which include the energy linearity, efficiency response and neutron/gamma discrimination are guaranteed for neutron detection in the energy range from 0 to 3000 keVee. Regarding the neutron/gamma discrimination capability, four pulse shape discrimination (PSD) methods which are the threshold crossing time (TCT).
7/4/2019 3:43:36 AM +00:00
A study on characteristics and internal exposure evaluation of radioactive aerosols during pipe cutting in decommissioning of nuclear power plant
This study investigated the annual exposure limits of various countries, which can be used as an indicator in evaluating workers' internal exposure to radioactive aerosol during pipe cutting in the process of decommissioning nuclear power plants, and the growth and dynamics of aerosol. Also, to evaluate it, the authors compared/analyzed the cases of aerosol generated when activated pipes are cut in the process of nuclear power plants and the codes for evaluating internal exposure.
7/4/2019 3:43:17 AM +00:00
Effects of Zr-hydride distribution of irradiated Zircaloy-2 cladding in RIA-simulating pellet-clad mechanical interaction testing
The results of the EDC tests showed variation in the PCMI resistance of claddings with similar burnup and hydrogen content, making it difficult to clearly identify ductile-to-brittle transition temperatures. The EDC-tested samples of the present and previous work were investigated by light optical and scanning electron microscopy to study the influence of factors such as azimuthal variation of the Zr-hydrides and the presence of hydride rims and radially oriented hydrides.
7/4/2019 3:42:58 AM +00:00
Integrated Level 1eLevel 2 decommissioning probabilistic risk assessment for boiling water reactors
This article describes an integrated Level 1eLevel 2 probabilistic risk assessment (PRA) methodology to evaluate the radiological risk during postulated accident scenarios initiated during the decommissioning phase of a typical Mark I containment boiling water reactor. The fuel damage scenarios include those initiated while the reactor is permanently shut down, defueled, and the spent fuel is located into the spent fuel storage pool.
7/4/2019 3:42:35 AM +00:00
Focused ion beamescanning electron microscope examination of high burn-up UO2 in the center of a pellet
The local crystal orientations in these domains were close to that of the original grain. Most of the fission gas bubbles were located on the boundaries. Their shapes were far from spherical and far from lenticular. No interlinked bubble network was found. These observations shed light on previous unexplained observations. They plead for a revision of the classical description of fission gas release mechanisms for the center of high burn-up UO2. Yet, complementary detailed observations are needed to better understand the mechanisms involved.
7/4/2019 3:42:16 AM +00:00
Uncertainty analysis of containment dose rate for core damage assessment in nuclear power plants
This study proposes to conduct uncertainty analysis of CDR for core damage assessment. First, based on source term estimation, the Monte Carlo (MC) and point-kernel integration methods were used to estimate the probability density function of the CDR under different extents of core damage in accident scenarios with late containment failure. Second, the results were verified by comparing the results of both methods.
7/4/2019 3:41:57 AM +00:00
Effect of a surface oxide-dispersion-strengthened layer on mechanical strength of zircaloy-4 tubes
The mechanical strength of Zircaloy-4 increased with the formation of the ODS layer. The ring-tensile strength of Zircaloy-4 increased from 790 to 870 MPa at room temperature, from 500 to 575 MPa at 380C, and from 385 to 470 MPa at 500C. Strengthening became more effective as the test temperature increased. It was noted that brittle fracture occurred at room temperature, which was not observed at elevated temperatures.
7/4/2019 3:41:33 AM +00:00
Application plan for radiological exposure model using virtual realityebased radiological exercise system
. In the study, a model for estimating effective doses to the participants is proposed to evaluate the exercise system, using the effective dose rates at particular times and locations derived from a computer program. The effective dose received by a student when she/he follows a successful route is about a half of the dose received when she/he does not follow the exercise guide directions. In addition, elapsed time to finish an exercise when following a successful route is less than one-third of the time spent to finish an exercise when following the guide's directions.
7/4/2019 3:41:15 AM +00:00
Background reduction by Cu/Pb shielding and efficiency study of NaI(TI) detector
The effective reduction of background (1.04) by the copper mainly appeared in the energy range from X-ray up to 500 KeV, while for the total energy range the ratio is 1.01 relative to the lead only. In addition, a strong relation between the full-energy peak absolute efficiency and the detector well height was found using gamma-ray isotropic radiation point sources placed inside the detector well. The full-energy peak efficiency at a midpoint of the well (at 2.5 cm) is three times greater than that on the detector surface. The energy calibrations and the resolution of any single energy line are independent of the locations of the gamma source inside or outside of the well.
7/4/2019 3:40:51 AM +00:00
Mechanical analysis of the bow deformation of a row of fuel assemblies in a PWR core
The distribution of lateral hydraulic forces within the core row is estimated based on a two-dimensional Computational Fluid Dynamics model with porous media, assuming symmetric or asymmetric core inlet and outlet flow profiles. The influence of the creep rate on the bow amplitude is tested based on different creep models for guide tubes and fuel rods. Different FA initial states are considered: fresh FAs or FAs with higher burnup, which may be initially straight or exhibit an initial bow from previous cycles.
7/4/2019 3:40:29 AM +00:00
Examination of different socioeconomic factors that contribute to the public acceptance of nuclear energy
Results of the regression analysis generally verified the proposed hypotheses, especially regarding the positive impact of education or geological suitability and the negative effect of improved living standards and democracy on nuclear acceptance. We propose policy recommendations, including a better focus on education and communication and a thorough consideration of the social and geological conditions a country needs to make before deciding to go nuclear.
7/4/2019 3:40:11 AM +00:00
Thermal transport in thorium dioxide
In this research paper, the thermal transport in thorium dioxide is investigated by using nonequilibrium molecular dynamics. The thermal conductivity of bulk thorium dioxide was measured to be 20.8 W/m-K, confirming reported values, and the phonon mean free path was estimated to be between 7 and 8.5 nm at 300 K.
7/4/2019 3:39:49 AM +00:00
Multi-unit Level 1 probabilistic safety assessment: Approaches and their application to a six-unit nuclear power plant site
This article provides several detailed approaches that are applicable to multi-unit Level 1 PSA for sites with up to six or more reactor units. To validate the approaches, a multi-unit Level 1 PSA model is developed and the site core damage frequency is estimated for each of four representative multi-unit initiators, as well as for the case of a simultaneous occurrence of independent single-unit initiators in multiple units.
7/4/2019 3:39:23 AM +00:00
AIMS-MUPSA software package for multi-unit PSA
This paper deals with the methodology and software to quantify a PSA scenarios for a multi-unit site. Two approaches are developed to quantify a multi-unit PSA. One is to use a minimal cut set approach, and the other is to use a Monte Carlo approach.
7/4/2019 3:39:08 AM +00:00
Self-pressurization analysis of the natural circulation integral nuclear reactor using a new dynamic model
Self-pressurization analysis of the natural circulation integral nuclear reactor through a new dynamic model is studied. Unlike conventional pressurized water reactors, this reactor type controls the system pressure using saturated coolant water in the steam dome at the top of the pressure vessel. Selfpressurization model is developed based on conservation of mass, volume, and energy by predicting the condensation that occurs in the steam dome and the flashing inside the chimney using the partial differential equation.
7/4/2019 3:38:51 AM +00:00
Multi-unit Level 2 probabilistic safety assessment: Approaches and their application to a six-unit nuclear power plant site
In this study, the main purpose is to develop a multi-unit Level 2 PSA method and apply it to full-power operating six-unit OPR1000. Multi-unit Level 2 PSA method consists of three steps: (1) development of single-unit Level 2 PSA; (2) extracting the mapping data from plant damage state to source term category; and (3) combining multi-unit Level 1 PSA results and mapping fractions.
7/4/2019 3:38:30 AM +00:00
Performance evaluation of METAMIC neutron absorber in spent fuel storage rack
The purpose of the neutron absorber materials is to preclude neutronic coupling between adjacent fuel assemblies and to maintain the fuel in a subcritical storage condition. METAMIC neutron absorber has been used in high-density storage racks. But, neutron absorber materials can be subject to severe conditions including long-term exposure to gamma radiation and neutron radiation.
7/4/2019 3:38:08 AM +00:00
Review of the regulatory periodic inspection system from the viewpoint of defense-in-depth in nuclear safety
. In this study, the domestic periodic inspection system currently in use was analyzed from the perspective of defense in depth in nuclear safety. In addition, the analysis results were compared to the U.S. NRC's safety inspection system to obtain consistency and lessons in this study. As a result of analysis, the NRC's safety inspections were distributed almost evenly at the all levels of defense in depth, while in the case of domestic inspection, they were heavily focused on the level 1 of defense in depth.
7/4/2019 3:37:49 AM +00:00
Estimation of nuclear heating by delayed gamma rays from radioactive structural materials of HANARO
To improve the accuracy and safety of irradiation tests in High flux Advanced Neutron Application ReactOr (HANARO), the nuclear energy deposition rate, which is called nuclear heating, was estimated for an irradiation capsule with an iridium sample in the irradiation hole in order. The gamma rays emitted from the radioisotopes (RIs) of the structural materials such as flow tubes of fuel assemblies and heavy water reflector tank were considered as radiation source.
7/4/2019 3:37:31 AM +00:00
Particle image velocimetry measurement of complex flow structures in the diffuser and spherical casing of a reactor coolant pump
In the present study, flow measurement using particle image velocimetry is implemented to reveal flow features of the RCP model. Velocity and vorticity distributions in the diffuser and spherical casing are obtained. The results illuminate the complexity of the flows in the RCP. Near the lower end of the discharge nozzle, three-dimensional swirling flows and flow separation are evident.
7/4/2019 3:37:05 AM +00:00
Reactivity feedback effect on loss of flow accident in PWR
In this work, the reactor kinetics capability is used to compute the design safety parameters in a PWR due to complete loss of coolant flow during protected and unprotected accidents. A thermal-hydraulic code coupled with a point reactor kinetic model are used for these calculations; where kinetics parameters have been developed from the neutronic SRAC code to provide inputs to RELAP5-3D code to calculate parameters related to safety and guarantee that they meet the regulatory requirements. In RELAP5-3D the reactivity feedback is computed by both separable and tabular models.
7/4/2019 3:36:50 AM +00:00
Investigation of the relationship between earthquakes and indoor radon concentrations at a building in Gyeongju, Korea
This article measured and analyzed the indoor radon concentrations at one university building in Gyeongju, Republic of Korea, to investigate if there is any relationship between earthquakes and indoor radon concentration. Since 12 September 2016, when two 5.1 and 5.8 magnitude earthquakes occurred, hundreds of aftershocks affected Gyeongju until January 2017. The measurements were made at the ground floor of the Energy Engineering Hall of Dongguk University in Gyeongju over a period between February 2016 and January 2017.
7/4/2019 3:36:30 AM +00:00
A frame work for heat generation/absorption and modified homogeneouseheterogeneous reaction in flow based on non-DarcyeForchheimer medium
The present work aims to report the consequences of DarcyeForchheimer medium in flow of Cross fluid model toward a stretched surface. Flow in porous space is categorized by DarcyeForchheimer medium. Further heat transfer characteristics are examined via thermal radiation and heat generation/absorption. Transformation procedure is used.
7/4/2019 3:36:16 AM +00:00
Radiation damage in helium ioneirradiated reduced activation ferritic/martensitic steel
The average bubble size increases and the bubble density decreases with an increasing irradiation temperature from 200C to 350C. Both the average size and density of the bubbles increase with an increasing irradiation dose from 2 dpa to 8 dpa. Bubbles with smaller size and lower density were observed in the SMATed samples but not in the un-SMATed samples irradiated in the same conditions, which indicate that GBs play an important role during irradiation, and sink strength increases as grain size decreases.
7/4/2019 3:35:53 AM +00:00
A negative reactivity feedback driven by induced buoyancy after a temperature transient in lead-cooled fast reactors
Consideration is given to the possibility to use changes in buoyancy as a negative reactivity feedback mechanism during temperature transients in heavy liquid metal fast reactors. It is shown that by the proper use of heavy pellets in the fuel elements, fuel rods could be endowed with a passive self-ejection mechanism and then with a negative feedback.
7/4/2019 3:35:36 AM +00:00