bluuebunny/crossref_metadata_2025_split huggingface dataset:
In-Plane Flexibility Factor of 90 Degree Long Radius Elbows With Large Diameter
Authors: Haji Mohammad Karim Milad 
Published: October 2021

Abstract
Bend flexibility factor is defined as the ratio of rotation of a pipe bend to that of a straight pipe of the same diameter, wall thickness and length under the action of the same bending moment. In stress analysis of piping systems with the beam method, this factor is of great importance and plays a direct role in the formation of the stiffness matrix of a system. The exact calculation of this coefficient results in the precise amount of force and moment being obtained on anchor points (i.e., equipment nozzles) and also in stopper and guide restraints. Different codes such as ASME B31.3 and B31.1 present a formula for this factor without consideration of the end effect (constraint of bend ends by the adjacent straight pipe). Another limitation is that these formulas are valid only within the range of D/T ≤ 100 (diameter to thickness). In this paper the effect of adjacent straight pipes on in-plane flexibility factor of long radius 90-degree elbows has been investigated and it has also been demonstrated that the equation presented in ASME B31J-2017 as the minimum required length for the attached straight pipe is highly accurate and greater values do not have much effect on elbow flexibility. Finite element analysis (FEA) studies have been carried out on 31 models with various diameters and thicknesses for both D/T ≤ 100 and D/T &gt; 100 and in all cases the high precision of the given equation in B31J-2017 is indicated. Also, a new formula of in-plane flexibility factor (with consideration of the end effect) for long radius-90degree elbows is presented that has acceptable accuracy in all ranges of D/T. The new formula reveals that the B31 equation also has an acceptable accuracy even for D/T &gt; 100.
Effect of the Third Body Layer on Fretting Wear Behavior of 316 Stainless Steel
Authors: Zhang Shengzan , Liu Liyan , Ma Xu , Tan Wei , Zhu Guorui 
Published: October 2021

Abstract
It is very important to evaluate the fretting wear damage of heat exchanger tube in steam generator. In this study, the self-designed high-temperature fretting wear experimental equipment was used to conduct experimental studies on 316 stainless steel, commonly used as steam generator tube in nuclear power plants, at 95 °C for 24h, 48h, 72h and 120h, respectively. The effect of TBL on fretting wear behavior was analyzed. The results show that due to the formation of the third body layer, fretting wear damage does not increase significantly before 72 h. With the accumulation of damage, the third body layer was worn out and the damage continued to increase. The influence of the third body layer on the fretting wear behavior cannot be ignored.
An Application of the Brittle Fracture Criterion Gp Method to a RPV Type Geometry – Towards the Industrialization of the Method
Authors: Zheng Bin , Liu Han , Jules Samuel , Xie Hai , Shi Kaikai 
Published: October 2021

Abstract
With the life extension of Nuclear Power Plants worldwide, new challenges have emerged in engineering calculations. These challenges often stem from the difficulty to demonstrate an adequate margin for some key components, which have gradually been ageing during the operation of the plant. In particular, the Reactor Pressure Vessel (RPV) is impacted by the irradiation, and the risk of brittle fracture under severe cold shocks must be assessed.
In parallel to conventional approaches, a significant amount work has been performed over the past 20 years in France to adapt the historic Griffith energy release-rate approach to engineering space. The work was initiated by Francfort and Marigo[1]who set up a new elastic fracture theory, extended from the Griffith approach. Lorentz and Wadier[2][3] have since then improved the model which is based on several ingredients including the application of an energy minimization principle, the definition of a specific damage model and the use of a notch to represent the crack.
Among other advantages, the Cleavage brittle fracture energy approach parameter (Gp) method has been developed as a true engineering approach and hence is relatively easy to implement in a FEA software: it has already been implemented into code_aster developed by EDF R&D [4]. Recently, CEA also implemented the method in Cast3M [5].
Beyond the application in France, and in the wake of a simple comparison benchmark launched in 2018 with CNNC/NPIC from China on a CT specimen [6], a calculation on a RPV type geometry was initiated. This is the second step of a larger effort aiming at working together on establishing a strong industrial basis to demonstrate applicability in engineering and structural integrity space.
The paper provides the progress achieved in the benchmark work and the results obtained in the frame of the work jointly led with company B in the field.
Application of 3D Constraint-Based Fracture Mechanics for the Determination of R-Curves of Thermal Aged 16MND5 Steel
Authors: Liu Zheng , Wang Xin , Miller Ronald E. , Shen Yueyin , Chen Xu 
Published: October 2021

Abstract
In the current work, the comprehensive combined effects of thermal aging, and three-dimensional (3D) in-plane and out-of-plane constraints on the fracture resistance curves (J-R) of reactor pressure vessel (RPV) steel, 16MND5 were investigated. First, the fracture experiments of RPV steel with different thermal aging durations using variously sized clamped single edge notched tension (SENT) specimens, were summarized. Then, 3D finite element method (FEM) was used to determine the constraint parameters for the tested specimens. From the analysis results, it was shown that the normalized T11, and the independent portion of T33 can accurately quantify the in-plane and out-of-plane constraint levels, respectively. Next, the in-plane and out-of-plane constraint-quantified R-curves were developed. Results showed that the effects of thermal aging, in-plane and out of-plane constraints on fracture toughness present significant interactions. The specific characteristics observed are: the influence of constraints on fracture toughness decreases with the increase of thermal aging duration, especially the in-plane constraint effect; the effect of thermal aging on fracture behavior is more significant under low constraint conditions. Further, the current in-plane and out-of-plane constraint dependent R-curves can easily reproduce all tested R-curves determined by clamped SENT specimens. It was also shown that they can accurately predict R-curves of pin-loaded SENT specimens or real RPV cracked structures under different thermal aging durations.
Reactive CFD Simulation of Fixed Coke Formation in an Industrial RFCC Riser Reactor
Authors: Chen Sheng , Kang Haoyuan , Wang Mengke , Liu Cenfan , Lin Haitao , Liu Juanbo 
Published: October 2021

Abstract
Severe fixed Coke in the industrial residue fluid catalytic cracking (RFCC) riser reactor often results in the reduction of product yield and unplanned unit shutdown. It is difficult to simultaneously depict physical and chemical formation of fixed coke near wall due to no approach and coking model. In this paper, the complex gas-solid-liquid three phase flow, mixing and cracking reaction are in agreement with the industrial data by 3D reactive simulation with multiphase Eulerian granular model coupling with the vaporization empirical correlation and the energy-minimization multi-scale (EMMS) drag and mass transfer models. A new coking index is developed to predict the formation possibility of fixed coke based on the 3D accurate simulation. The variations of coking profiles at different diameter of oil droplet are investigated. The results indicate that the fixed coke formation can be well depicted by the coking index. The predicted of fixed coke in the feed injection zone is same with the actual positions in industrial unit, which mainly located near the walls of the 0.5∼3.0m height above the feed nozzles and the circumferential between adjacent nozzles. The feed oil droplet size can improve the formation possibility of fixed coke.
Research and Application of Safety Valves Inspection Method Based on Failure and Risk Big Data
Authors: Xing Jian , Ai Shuping , Han Zhiyuan 
Published: October 2021

Abstract
Inspection interval of safety valves is generally at least once a year specified by the Safety Technical Supervision Regulations for Safety Valves (TSG ZF001-2006) in China, while the maintenance interval of production equipment in oil refining and chemical enterprises is usually 3–5 years. There is a prominent problem that inspection interval and maintenance interval is not consistent. This paper reveals the main failure modes, opening rate as well as maintenance replacement rate by analyzing the operation condition of 24720 safety valves of 322 typical units in oil refining and chemical industry. Moreover, the engineering application data of 44692 safety valves carried out with Risk-Based Inspection (RBI) method in the past eight years are statistically analyzed to reveal the risk distribution and risk level of safety valves. Based on the failure and risk level big data of safety valves, this paper proposes the safety valves inspection method to solve the contradiction between inspection interval and maintenance interval, which maybe further promote the legal compliance and long-term safe operation of production units in oil refining and chemical enterprises. The advantages and limitations of this method are summarized by sharing the engineering application cases in a petrochemical company about Safety valves inspection based on big data of failure and risk.
Research and Examination of Seismic Safety Evaluation and Function Maintenance for Important Equipment in Nuclear Facilities
Authors: Furuya Osamu , Fujita Satoshi , Muta Hitoshi , Ohtori Yasuki , Itoi Tatsuya , Okamura Shigeki , Minagawa Keisuke , Nakamura Izumi , Fujimoto Shigeru , Otani Akihito , Nishida Akemi , Watakabe Tomoyoshi 
Published: October 2021

Abstract
Since the Fukushima accident, with the higher safety requirements of nuclear facilities in Japan, suppliers, manufacturers and academic societies have been actively considering the reconstruction of the safety of nuclear facilities from various perspectives. The Nuclear Regulation Authority has formulated new regulatory standards and is in operation. The new regulatory standards are based on defense in depth, and have significantly raised the levels of natural hazards and have requested to strengthen the countermeasures from the perspective of preventing the simultaneous loss of safety functions due to common factors. Facilities for dealing with specific serious accidents are required to have robustness to ensure functions against earthquakes that exceed the design standards to a certain extent. In addition, since the probabilistic risk assessment (PRA) and the safety margin evaluation are performed to include the range beyond the design assumption in the safety improvement evaluation, it is very important to extent the special knowledge in the strength of important equipment for seismic safety. This paper summarizes the research and examination results of specialized knowledge on the concept of maintaining the functions of important seismic facilities and the damage index to be considered by severe earthquakes. In the other paper, the study on reliability of seismic capacity analysis for important equipment in nuclear facilities will be reported.
The Creep Crack Growth Behavior of GH3535 Superalloy at 650°C
Authors: Guangcheng Fan , Wanxia Wang , Jianping Tan , Kexian Shi , Songlin Wang , Yanling Lu 
Published: October 2021

Abstract
GH3535 alloy is a kind of Ni-Mo-Cr based structural material independently developed by China especially for thorium molten salt reactor (TMSR) that is the only liquid fueled reactor among the six fourth-generation advanced fission reactors. GH3535 alloy has good high temperature mechanical properties and the purpose of this work is to evaluate the creep crack growth (CCG) performance of it. The CCG tests on GH3535 alloy were conducted with the compact tension (CT) specimen under different effective stress intensity factors Kn at 650°C. Based on this, the relationship between creep crack initiation time ti, creep crack growth rate da/dt and fracture parameter C* were obtained and compared with the result predicted by Nikbin-Simth-Webster (NSW) model. The microstructural degradation at creep rupture was characterized using scanning electron microscopy (SEM). The results show that in the double logarithmic coordinate system, the fracture parameter C* has a linear relationship with the crack growth rate da/dt and the crack initiation time ti which show C* can correlate well with the crack growth rate and crack initiation time. The NSW model under plane stress can better predict creep crack growth behavior. The crack propagates in two ways: firstly, it propagates along the grain boundary, and then enters the rapid propagation stage, where the ductile dimple fracture occurs.
Failure Analysis and Intelligent Prevention and Control Technology of High Pressure Air Cooler in Hydrogen Environment
Authors: Ou Guofu , Jin Haozhe , Gu Yong , Liu Xiaofei , Yu Chenyang 
Published: October 2021

Abstract
The failure anatomy and simulation of high pressure air cooler bundle in hydrogenation unit are analyzed. Based on the typical working condition data, DCS and Lims data during the calibration period of the unit, the process simulation of the hydrogenation effluent system was carried out in Aspen Plus, and the cooling separation process of the hydrogenation effluent was simulated by using the material reverse sequence backward pushing method. According to the distribution of oil, gas and water multiphase flow in the air cooler, the temperature of ammonium salt crystallization, the content of liquid water, the concentration of ammonium sulphate hydrogenation, the corrosion factor and the pH value were calculated. The results showed that there were corrosion risks of ammonium salt crystallization and erosion corrosion in the air cooler. At the same time, according to the state and physical parameters, the erosion risk of air cooler inlet pipe and air cooler is predicted and analyzed, and the characteristic parameters such as shear stress, mass transfer coefficient and water phase fraction are used to represent the erosion risk. The anatomic analysis results of the failed bundle are verified by the process and fluid mechanics simulation. In view of corrosion analysis, corrosion prevention and control are carried out by means of technological protection, mainly by adjusting the water injection volume and water injection location. Based on the design of resistance to flow corrosion, the compound liner of air cooler tube bundle was modified. A corrosion expert supervision system was developed to monitor the running state of the hydrogenation effluent system in real time. The process calculation model and fluid dynamics simulation prediction model are embedded into the system to calculate each characteristic parameter and present the corrosion status of the current device to the enterprise, so that the enterprise can timely take measures to avoid safety accidents.
Thermal Analysis Evaluations Using the Dry Cask Simulator
Authors: Suffield S. R. , Richmond D. J. , Fort J. A. 
Published: October 2021

Abstract
Different thermal analysis models were developed to simulate the dry cask simulator (DCS). The DCS is an experiment designed to simulate dry storage of a single boiling water reactor fuel assembly under a variety of heat loads and internal pressures. The DCS was set up and tested in both a vertical and horizontal configuration to determine cladding temperatures in vertical and horizontal dry cask storage systems. The models included a detailed STAR-CCM+ model with the fuel assembly geometry explicitly modeled, a porous STAR-CCM+ model with the fuel assembly geometry modeled as a porous media region with calculated effective properties, and a COBRA-SFS model. COBRA-SFS is a thermal-hydraulic code developed for steady-state and transient analysis of multi assembly spent-fuel storage and transportation systems. STAR-CCM+ is a commercial computational fluid dynamics (CFD) code. Both a detailed and porous STAR-CCM+ model were developed to look at the effective thermal conductivity (keff) approach to modeling a fuel assembly. A keff fuel model is typically modeled in CFD thermal analyses due to its significantly lower computational costs. The models were run for a combination of low and high canister pressures (100 kPa and 800 kPa) and low and high internal heat loads (0.5 kW and 5 kW). Results from all three models were compared against experimental data taken from the DCS for the peak cladding temperature (PCT) and inlet air mass flow.
Proposal of Simulation Material Test Technique for Clarifying the Structure Failure Mechanisms Under Excessive Seismic Loads
Authors: Hashidate Ryuta , Kato Shoichi , Onizawa Takashi , Wakai Takashi , Kasahara Naoto 
Published: October 2021

Abstract
This paper proposes simulation material test technique using 99% lead - 1% antimony alloy instead of actual structural material. It is very essential to clarify the structure failure mechanisms under excessive seismic loads. However, structural tests using actual structural materials are very difficult and expensive. Therefore, the authors have proposed the structure test approach using lead alloys in order to simulate the structure failure mechanisms under the excessive seismic loads. Because the strength of such alloys is much inferior to that of the actual structural materials, failure phenomena can be observed by much small load. For demonstration of qualitative analogy between the failure mechanisms of the structures made of lead alloys under small loads and those of the actual structural materials under the actual loads, numerical analyses are required. In this study, the authors conducted material tests using lead alloy and verified the effectiveness of the simulated material tests. Moreover, the authors formulated inelastic constitutive equations (best fit fatigue curve equation and cyclic stress range – strain range relationship equation) of lead alloy based on the results of a series of material tests. Nonlinear numerical analyses, e.g. finite element analyses, can be performed using the proposed equations. A series of simulation material test technique enables structural tests and analyses using lead alloy to simulate the structure failure phenomena under excessive seismic loads. It is important to note that while mechanical behavior can be simulated by structural tests using such alloys, metallurgical evolutions cannot be simulated.
Dynamic Behavior of a Simplified Cantilever With Progressive Static Loading due to Ratchet Deformation
Authors: Kai Satoru , Kasahara Naoto , Ichimiya Masakazu 
Published: October 2021

Abstract
The importance of the severe accident mitigation under beyond design-basis events (BDBEs) was realized to achieve the nuclear safety through the Fukushima accident. Failure mode estimation of essential components in nuclear facilities is necessary to take appropriate measures against the severe accident conditions. The failure mode of piping systems exposed to excessive seismic loading was found to be ratchet deformation followed by fatigue failure through many experimental tests in the past, whereas the failure of Test #37 of Pipe-fitting dynamic reliability program (PFDRP) conducted by EPRI was unexpected and its failure mechanism remains unclear, as it was often suspected to have been failed in plastic collapse. In the past research, the constant stress on the structure such as a dead-weight was revealed to significantly affect the failure mode and failure level of structures under seismic excitation. In this study, the constant stress components which can increase due to the ratchet deformation during a seismic excitation is focused and is analytically examined to clarify the effects on the failure mode of structures by using a cantilever structure with various dead-weight conditions and a constant cycles of sinusoidal waves which essentially represents the seismic loading with specific frequency ratios to establish the failure estimation of a structure exposed to seismic loading.
Fracture Toughness in Postulated Crack Area of PTS Evaluation in Highly-Neutron Irradiated RPV Steel
Authors: Ha Yoosung , Shimodaira Masaki , Takamizawa Hisashi , Tobita Tohru , Katsuyama Jinya , Nishiyama Yutaka 
Published: October 2021

Abstract
The Japanese Electric Association Code 4206-2016 requires that the semi-elliptical crack sized 10 mm in depth × 60 mm in length shall be postulated near the inner surface of a reactor pressure vessel (RPV) in pressurized thermal shock events. The fracture toughness distribution was investigated in the postulated crack area under the PTS events of unirradiated and highly-neutron irradiated RPV steels. Vickers hardness in heat-affected zone (HAZ) due to stainless overlay cladding and 10 mm from the cladding were higher than that of a quarter thickness position, where the surveillance specimens are machined, for both unirradiated (E1) and irradiated (up to 1 × 1020 n/cm2, WIM) materials. Fracture toughness of HAZ and 10 mm from the cladding was higher for the above highly-neutron irradiated material. The same result was obtained in the unirradiated material. Therefore, it was confirmed that fracture toughness obtained from surveillance specimens can provide conservative assessment of structural integrity of RPV.
Assessment of Residual Stress for Thick Butt-Welded Plate of a Reactor Pressure Vessel Steel
Authors: Ha Yoosung , Okano Shigetaka , Takamizawa Hisashi , Katsuyama Jinya , Mochizuki Masahito 
Published: October 2021

Abstract
Residual stress is one of the most important influence factors in the structural integrity assessment of the nuclear components. However, at the present, there are few examples of residual stress measurements for thick butt-welded plates such as the reactor pressure vessels (RPVs). In this study, the residual stresses generated by butt-welding of thick plates of RPV steel, which have almost the same thickness of 140 mm as actual boiling water reactor RPV, were measured for post-welded heat-treated condition using the deep-hole-drilling technique. In addition, thermo–elastic–plastic creep analyses with or without considering the phase transformation in the heat-affected zone using the finite element analyses (FEAs) were performed to evaluate the residual stress produced by butt-welding and post-weld heat treatment. In the analysis considering phase transformation using the commercial FEM analysis code Abaqus, the fractions of the phases, such as martensite, bainite and ferrite, are calculated based on the kinetics of phase transformation. By comparing the analytical results with the experimentally determined values, we found good agreements for the residual stress distributions within the weld and the base material near the welded part. In the presentation, the effect of phase transformation on residual stress distribution of butt-weldment of thick plate will be discussed.