bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uncertainty Quantification for the Development of Mechanistic Hydride Behavior Model for Spent Fuel Cladding Storage and Transportation
Authors: Duchnowski Edward M. , Seo Seokbin , Brown Nicholas R. 
Published: October 2020

Abstract
During operation of light water reactors hydrogen from the primary coolant is absorbed within the zirconium cladding and is able to migrate and redistribute within the cladding. The hydrogen in solid solution is able to precipitate, forming zirconium hydrides which results in a decrease of ductility of the cladding and ultimately an increase in likelihood of cladding failure, especially in conditions such as transport or storage of nuclear fuel rods. In collaboration with other universities, industries, and national laboratories the overarching goal of this project is to enhance the development for modeling hydride behavior to be implemented into the BISON fuel performance tool. The University of Tennessee-Knoxville (UTK) has been tasked with quantifying the uncertainty in the models developed within this project as well as quantifying the sensitivity to the most significant parameters of uncertainty.
The BISON fuel performance code has been shown to overpredict the total concentration of hydrogen at cold regions of a temperature profile, thus a sensitivity study was performed to quantify the impact that key diffusion parameters have on the local concentration of hydrogen at the cold end of a 1-D model subjected to an asymmetric temperature profile. It is shown within this document that the diffusion activation energy and the pre-exponential factor, values within the diffusion coefficient of hydrogen, have a large impact on the local concentration of hydrogen and their importance increases for an increase in annealing time.
Development of Ex-Vessel Phenomena Analysis Model for Multi-Scenario Simulation System, SPECTRA
Authors: Uchibori Akihiro , Aoyagi Mitsuhiro , Takata Takashi , Ohshima Hiroyuki 
Published: October 2020

Abstract
The simulation system named SPECTRA for a severe accident in sodium-cooled fast reactors has been developed. The SPECTRA computes in- and ex-vessel phenomena and evaluates various scenarios during the severe accident. This paper provides a newly developed computational models for the ex-vessel phenomena including gas and aerosol transport, sodium-concrete interaction, and sodium fire as a part of the SPECTRA. The base module computing thermal hydraulics behavior by a lumped mass model was verified through the analysis of a 2-cells ventilation problem. The computational result of the SPECTRA agreed with the theoretical solutions both in the case with and without temperature change. The sodium-concrete interaction model was verified through code to code comparison. The computational result showed that ablation of a concrete surface started after surface temperature reached to a certain value. The computed ablation depth almost completely agreed with the result by the CONTAIN-LMR code. The ex-vessel module was applied to the computation assuming sodium leak from a reactor vessel and a primary cooling loop. This computation demonstrated increase of temperature and pressure due to sodium-concrete interaction and sodium fire.
Study on the Interaction Between Safety-Related and Non Safety-Related Items in the Component Cooling Water System Room of the Qinshan Nuclear Power Plant in the Earthquake Condition
Authors: Zhang Liang , Xu Gang , Wang Yue , Chen Li , Zhou Shao Chong 
Published: October 2020

Abstract
Safety-related items in nuclear power plants are now generally placed separately from the non-safety-related items, but it was not strictly required before. Therefore, it is very important to study whether the non-safety-related items will affect the safety-related items when they are dropped down in an earthquake situation, which determines the safety of a nuclear power plant and its future life extension applications.
This research was based on the cooling water system room with the safety and non-safety related items installed together, as an example to study whether the non-safety-related items such as vent pipes and DN50 fire fighting pipes arranged above will damage the DN300 pipes and valves arranged below when earthquakes occur.
For the experiments, the relative positions of objects in the room was reproduced by 1: 1. The pressure-holding performance of the pipe was used as a criterion for the damage. The research results of the experiments show that when the 10-meter-long DN50 pipe was dropped from the position of 8 meters height and the 8-meter-long vent dropped from position of 3.6 meters height, they do not affect the integrity of the DN300 valve and pipe below. After the experiment, pressure drop in two hours for the pipe is less than 0.1%. The main body of the valve does not fail neither.
The numerical simulation study also shows that there is no failure phenomenon in the simulation as well. Compared with the test results, the impact acceleration and the vent deformation both have the same trend.
Two-Dimensional Full Core Analysis of IFBA-Coated TRISO Fuel Particles in Very High Temperature Reactors
Authors: Alrwashdeh Mohammad , Alameri Saeed A. 
Published: October 2020

Abstract
The Prismatic-core Advanced High Temperature Reactor (PAHTR) is a very high temperature reactor type which is one of promising reactor type technologies classified as Generation IV by the International Forum. The new technology designs are identified as being proliferation resistant, safe, economical, efficient, and long fuel cycle. In this paper, the continuous-energy Monte Carlo method is capable of capturing all of the necessary reactor physics parameters using high fidelity two dimensional model with Serpent Monte Carlo code, and applied for a large scale reactor core loaded with TRi-structural ISOtropic (TRISO) particle by taking into account the double heterogeneity effect. These analyses were performed for PAHTR reactor core that utilizes TRISO particles fuel embedded in graphite matrix by applying a new innovative idea of adding Integral Fuel Burnable Absorber (IFBA) as an additional coating layer with a designated thickness. Adding IFBA coating could lead to compressed excess reactivity at the Beginning of Cycle (BOC), and extended burnup cycle. The additional IFBA coating layer is placed in the outer surface of the fuel kernel and covered by the buffer layers that compose the TRISO fuel particle. Neutronic calculations were performed for both TRISO particle unit cell and for full core with homogenous distribution of IFBA coating.
Computational Study on the Spherical Laminar Flame Speed of Hydrogen-Air Mixtures
Authors: Trianti Nuri , Motegi Kosuke , Sugiyama Tomoyuki , Maruyama Yu 
Published: October 2020

Abstract
The computational fluid dynamics (CFD) have been developed to analyze the correlation equation for laminar flame speed of hydrogen-air mixtures. This analysis was carried out on the combustion of hydrogen-air mixtures performed at the spherical bomb experiment facility consists of a spherical vessel equipped (563 mm internal diameter). The facility has been designed and built at CNRS-ICARE laboratory. The simulation was carried out using the reactingFoam solver, one of a transient chemical reaction solver in OpenFOAM 5.0. The LaunderSharmaKE model was applied for turbulent flow. The interaction of the chemical reaction with the turbulent flow was taken into account using PaSR (Partial Stirred Reactor) model with 19 elementary reactions for the hydrogen combustion. The initial condition of spherical flame analysis was set so as to be consistent with those of the experiment. The position of the flame front was detected by the steep drop of hydrogen mass fraction in the spherical radii, and the flame propagation velocity was estimated from the time-position relationship. The analysis result showed the characteristic of spherical flame acceleration was qualitatively reproduced even though it has a discrepancy with the experiment. After validating the calculation of spherical experiments, a laminar burning velocity correlation is presented using the same boundary conditions with the variation of hydrogen concentration, temperature, and pressure. The calculation of laminar flame speed of hydrogen-air mixtures by reactingFoam use reference temperature Tref = 293 K and reference pressure Pref = 1 atm with validated in the range of hydrogen concentration 6–20%; range of temperature 293–493 K; and range of pressure 1–3 atm.
Experiment and Analysis on Isolation Condenser Simulator Using Pressurized Steam
Authors: Ono Kosuke , Yamamoto Yasunori , Mori Masayoshi , Takada Tetsuya 
Published: October 2020

Abstract
Isolation condensers (ICs) are important passive cooling systems in BWRs. After the Fukushima Daiichi Nuclear Power Station accident, concerns if the IC was able to restart with the inflow of hydrogen were arose. Because ICs lose heat removal ability when non-condensable gas inflow occurs, accurate evaluation of the effect is necessary. To develop analysis methods, as an initial stage, experiments and analyses considering only high-pressure steam and water were conducted. The experiment was done by an isolation condenser simulator which contains an accumulator with heaters inside, and a heat transfer tube. From the experiment, all steam was condensed at the heat transfer tube and the approximate position of complete condensation was confirmed from the temperature distribution and the observation. The experiment provided data such as temperature distribution, natural circulation flow rate, and pressure to compare with the analysis. The analyses were conducted for 4 cases of void fraction values at the heat transfer tube inlet and found that it has a high sensitivity to condensation. The reason is estimated to be the difference in inflow velocity that strongly depends on the void fraction even if the mass flow rate is constant. And the initial condition of the liquid film also affected condensation process. Heat removal at the section before the heat transfer tube should be considered to adjust void fraction at the inlet of heat transfer tube.
Transient Analysis of Dedicated Pressure Relief Valve Under High-Pressure Condition in Severe Accident for Tianwan 56 Nuclear Power Plant
Authors: Xu Youyou , Deng Jian , Wang Xiaoji , Wu Lingjun , Zhang Ming , Qian Libo , Cai Rong , Zhong Lei , Du Zhengyu 
Published: October 2020

Abstract
In the management of severe accident of nuclear reactor, the pressure relief of reactor coolant system (RCS) is an important mitigation measure to prevent high pressure core melt (HPCM). In the safety system improvement of Tianwan56 nuclear power plant, the optimization measure of adding the dedicated pressure relief valve (DPRV) for severe accident were adopted. This improvement allows the reactor to release the pressure of RCS before the reactor vessel being damaged to mitigate the consequence of reactor melt accident under high-pressure condition. Based on the analysis of severe accident sequences, the total loss of feed water accident is confirmed to cover the various severe accident consequences which may lead to HPCM accident. This paper studied the transient characteristics of total loss of feed water accident sequences, and the factors such as valve opening delay on the operating temperature of the valve were researched. Finally, the representative and envelope operating condition of DPRV under severe accident was clarified. Besides, the temperature curve of fluid passing through the valve and the maximum temperature the valve experienced were obtained. This research provides the valuable and indispensable basis to the operability and integrity analysis of DPRV in severe accident.
Numerical Validation of AQUA-SF in SNL T3 Sodium Spray Fire Experiment
Authors: Sonehara Masateru , Aoyagi Mitsuhiro , Uchibori Akihiro , Takata Takashi , Ohshima Hiroyuki , Clark Andrew J. , Louie David 
Published: October 2020

Abstract
In order to investigate the effect of sodium combustion, Sandia National Laboratories (SNL) and Japan Atomic Energy Agency (JAEA) have exchanged information of sodium combustion modeling and related experimental data in the framework of Civil Nuclear Energy Research and Development Working Group (CNWG). This collaboration includes a benchmark analysis of the SNL Surtsey spray combustion experiment (SNL T3 experiments) using AQUA-SF and SPHINCS in JAEA. In this paper, investigation into multi-dimensional effect and best estimate for T3 experiment with AQUA-SF are conducted as validation and verification of the code. A spray combustion is characterized by formation of sodium droplet cloud due to pressure difference and their spreading with combustion. Therefore, the combustion phenomenon will be much affected by spatial distributions of parameters such as gas temperature, gas velocity and oxygen concentration.
As a best estimate analysis, the spray burning duration is adjusted in the computation in order to take into account the temporary suppression of the spray combustion observed in the experiment. Furthermore, droplet size of SPHINCS and AQUA-SF are optimized to represent the T3 experimental results. For the best estimate in AQUA-SF, sodium droplet size needs to be set larger than SPHINCS in order to decrease the surface area and suppress the spray burning rate. These adjustment leads to more precise representation of the measurements in T3 experiment.
On Effects of Temperature Boundary Conditions on Heat Transfer in Turbulent Low-Prandtl-Number Flows
Authors: Otic Ivan 
Published: October 2020

Abstract
One important issue in understanding and modeling of turbulent heat transfer is the behavior of fluctuating temperature close to the wall. Common engineering computational approach assumes constant heat flux boundary condition on heated walls. In the present paper constant heat flux boundary condition was assumed and effects of temperature fluctuations are investigated using large eddy simulations (LES) approach. A series of large eddy simulations for two geometries is performed: First, forced convection in channels and second, forced convection over a backward facing step. LES simulation data is statistically analyzed and compared with results of direct numerical simulations (DNS) from the literature which apply three cases of heat flux boundary conditions: 1. ideal heat flux boundary condition, 2. non-ideal heat flux boundary condition, 3. conjugate heat transfer boundary condition. For low Prandtl number flows LES results show that, despite very good agreement for velocities and mean temperature, predictions of temperature fluctuations may have strong deficiencies if simplified boundary conditions are applied.
Representativity Analysis Applied to TREAT Water Loop LOCA Experiment Design
Authors: Epiney Aaron S. , Woolstenhulme Nicolas 
Published: October 2020

Abstract
The Transient Reactor Test (TREAT) Facility at Idaho National Laboratory (INL) started testing new fuels and reactor technologies once again in 2018 and new experiments and tests are currently being designed like for example the water loop “TREAT Water Environment Recirculating Loop” (TWERL). During the design of such experiments, the designer must assess how close the experiment reproduces the physics (and other important phenomena) happening during a transient of interest compared to the full-size reactor the experiment attempts representing. Traditionally, to assess this “representativity” of the experiment, scaling theory involving expert judgment is needed. This paper presents a step towards a systematic modeling and simulation (M&S) informed methodology for experiment design. The new methodology compares a model of the full system and a model of the mock-up facility that are subject to the same perturbations. In this way, the “overlap” of the perturbed experiment and full-size facility model outputs can be analyzed and the “representativity” of the experiment determined. The paper presents a RELAP5-3D analysis, where TWERL LOCA calculations are compared to prototypic PWR LOCA calculations with respect to representativity. To inform the design of the TWERL experiments, i.e. to find the most “representative” configuration for the TWERL loop, different design parameters for TWERL have been optimized in the study.
Experimental Study of the Effect of Hydrogen Inflow on Passive Core Cooling System With Natural Circulation Flow
Authors: Yamamoto Yasunori , Mori Masayoshi , Ono Kosuke , Takada Tetsuya 
Published: October 2020

Abstract
Isolation Condenser (IC) is one of the passive core cooling systems with natural circulation flow, which is effective for safety measures against station black out. Once core uncover occurs, hydrogen generated in the core affects operating condition of ICs. To use ICs as an important safety measure not only for transient conditions but also for accident conditions, robustness of ICs against hydrogen inflow must be understood well. In this study, experiments with high pressure steam were conducted using experimental setup simulating IC, where helium was injected to simulate hydrogen effects. When the pressure in an accumulator increased high enough, natural circulation flow generated in the experimental loop. After the long-term operation, the pressure and the natural circulation flow rate achieved nearly constant. The pressure at quasi-steady state increased with increasing the helium injection amount. The pressure difference in a section including outlet side of a vertical pipe was slightly increased when helium was injected which may have indicated that the helium accumulated in the section and caused increment of the pressure loss. The startup pressure of the IC simulator also increased when helium was injected, where the driving force by the water head difference also decreased. Though long-term operations were performed after helium injection, the effect of injected helium on operating conditions of the IC remained for quasi-steady state conditions.
Experimental Study on Multi-Channel Jets in Plate Assembly Under Blockage Condition
Authors: Huijian Huang , Peng Wang , Dongyang Li , Tan Sichao 
Published: October 2020

Abstract
In the nuclear field, the reactor using plate fuel assembly forms multiple jets at exit. So, it’s meaningful to study multiple jets to learn the behavior of the coolant when it leaves the core. This paper uses PIV technology to study the flow characteristics of 9 jets at low Reynolds number. Firstly, the velocity field reveals that the pressure outside the jet is greater than the inside of the jet, which causes the jet to deflect and converge inward at z/w = 0–8. Then, the velocity field with different Re number is analyzed in the center plane, and find that the flow distribution is similar. Then, a detailed analysis is performed on the jet under specific conditions, and the merge point is discussed in the paper. At the same time, the first-order velocity tensor are also calculated in this paper. In addition, this article also analyzes the jet flow field after the central narrow channel was blocked. In this experiment, a plug was used to block the No. 5 jet by 1/3. And the flow redistribution is discussed in this case. The methods of flow calculation using PIV technology is established and compared with the real number of flowmeters, it’s found that the calculation method is rather accurate. On the other hand, the experiment find that the distribution of flow in each channel is not uniform, and the blocking condition make an increase in the flow of edge channels, which leads to the decreasing of flow in the blocked adjacent channel.
Numerical Analysis of Nuclear Facility Reinforced Concrete Wall and Roof Slab Behavior Under Close-in Explosions
Authors: Rongpeng Li , Yumin Li , Chunguang Sui , Di Jiang 
Published: October 2020

Abstract
With the change of anti-terrorism situation, civil unmanned aerial vehicles carrying small equivalent of explosives may cause damage to the reinforced concrete wall or roof of nuclear facilities at close range. Existing research has mostly focused on the overall damage caused by large equivalent explosives at medium and long distances. In this paper, the air overpressure peak curve and behavior of reinforced concrete slabs under small equivalent TNT close-in explosion conditions are calculated by numerical simulation methods and compared with empirical formulas and experimental results in the literature to verify. Furthermore, the numerical simulation method was used to evaluate the resistance of 300mm thick reinforced concrete slabs to close-in impacts of different mass TNT at a standoff distance of 0.4m.
Prevalence and risk factors for back pain in sports: a systematic review with meta-analysis
Authors: Wilson Fiona , Ardern Clare L , Hartvigsen Jan , Dane Kathryn , Trompeter Katharina , Trease Larissa , Vinther Anders , Gissane Conor , McDonnell Sarah-Jane , Caneiro JP , Newlands Craig , Wilkie Kellie , Mockler David , Thornton Jane S 
Published: October 2020

ObjectivesWe aimed to determine the prevalence of low back pain (LBP) in sport, and what risk factors were associated with LBP in athletes.DesignSystematic review with meta-analysis.Data sourcesLiterature searches from database inception to June 2019 in Medline, Embase, Cumulated Index to Nursing and Allied Health Literature (CINAHL), Web of Science and Scopus, supplemented by grey literature searching.Eligibility criteriaStudies evaluating prevalence of LBP in adult athletes across all sports.ResultsEighty-six studies were included (30 732, range 20–5958, participants), of which 45 were of ‘high’ quality. Definitions of LBP varied widely, and in 17 studies, no definition was provided. High-quality studies were pooled and the mean point prevalence across six studies was 42%; range 18%–80% (95% CI 27% to 58%, I2=97%). Lifetime prevalence across 13 studies was 63%; range 36%–88% (95% CI 51% to 74%, I2=99%). Twelve-month LBP prevalence from 22 studies was 51%; range 12%–94% (95% CI 41% to 61%, I2=98%). Comparison across sports was limited by participant numbers, study quality and methodologies, and varying LBP definitions. Risk factors for LBP included history of a previous episode with a pooled OR of 3.5; range 1.6–4.0 (95% CI 1.9 to 6.4). Statistically significant associations were reported for high training volume, periods of load increase and years of exposure to the sport.ConclusionLBP in sport is common but estimates vary. Current evidence is insufficient to identify which sports are at highest risk. A previous episode of LBP, high training volume, periods of load increase and years of exposure are common risk factors.