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Based on the enzymatic saccharification of the various pulps in the previous 0.8 l ultrasonic stirred tank reactor, the ultrasound-enhanced saccharification of waste papers such as newspaper, carton paper, office paper etc. was carried out in the same reactor as well as larger scale stirred tank reactors of size 3.2 and 6.4 l. The saccharification of each waste paper was less enhanced in the larger reactor at a given ultrasonic intensity. This could be attributed to the decrease in the ultrasonic intensity per reaction volume, i.e., the specific ultrasonic intensity. Most waste papers were more efficiently hydrolyzed with increasing specific ultrasonic intensities, although newspaper was less efficiently done for a too high specific intensity. Such an adverse effect might be due to the fact that some impurities in the newspaper such as lignin were activated by an intensive ultrasonic irradiation to form a rigid and closed network, which inhibited the access and adsorption of cellulase on to the substrate surface. The previous kinetic model was found to be applicable to analyze and simulate the saccharification of each waste paper in the different ultrasonic reactors. The ultimate conversion of a substrate based on the total sugar concentration estimated for an infinite reaction time could be correlated as a function of the ratio of initial substrate to enzyme concentrations at a fixed specific ultrasonic intensity. Either the apparent rate constant or the ultimate conversion increased and tended to approach a constant with an increase in the specific ultrasonic intensity except for the case of newspaper, while neither the apparent Michaelis constant, product inhibition constant nor glucose formation equilibrium constant was influenced by the specific ultrasonic intensity. [Copyright &y& Elsevier]

Pre-cooling for refueling high-pressure hydrogen not only avoids safety hazards but also extends the driving range of vehicles. In this paper, a simulation model for hydrogen refueling with a compact heat exchanger is developed to analyze the dynamic process in HRS with three-stage storage tanks. According to the simulated results, the hydrogen temperature at the heat exchanger's outlet is greatly influenced by the mass flow rate and the inlet temperature. The pre-cooling duration is a feasible method to save energy. Moreover, optimization discussions about the pre-cooling temperature and the pre-cooling duration have been carried out for the sake of the low final gas temperature, high SOC, and minimum energy consumption. If the ambient temperature decreases by 10 K, the optimal pre-cooling temperature could be adjusted to increase by 4 K. And if the initial vessel pressure increases by 2 MPa, the optimal pre-cooling duration could be shortened by 10 s. [Display omitted] • A refueling simulation model considering a heat exchanger model has been developed in a HRS with cascade storage system. • The hydrogen temperature at the heat exchanger's outlet is predicted and analyzed. • Impacts of pre-cooling duration on final gas temperature and energy consumption have been discussed. • The optimal pre-cooling temperature could increase by 4 K–6 K if the ambient temperature increases by 10 K. • The pre-cooling duration at the initial stage could be optimized by 10 s if the initial vessel pressure increases by 2 MPa. [ABSTRACT FROM AUTHOR]

Hydrogen has become a popular alternative energy to traditional fossil fuels due to its potential to contribute to a more sustainable future. It is recognized that the safety, efficiency, and economic aspects of hydrogen storage and transportation play an important role in the hydrogen energy industry. The development and commercialization of hydrogen energy are currently hindered by the structural integrity issue associated with hydrogen storage tanks. To tackle this structural integrity issue, a tangible structural health monitoring (SHM) technology is entailed for the health management of hydrogen storage tanks. Currently, flexible transducers are increasingly used to construct sensing systems and facilitate the deployment of SHM methods due to their superior properties such as conformality, low profile, and lightweight. This paper provides an overview of the SHM methods based on flexible sensing technology for hydrogen storage tanks. The most common damage modes caused by diverse factors during the service life for four types of hydrogen storage tanks are first summarized. The burgeoning flexible sensing technologies with corresponding damage characterization methods (including strain-based and elastic wave-based methods) are reviewed, and their applications in storage tanks are also discussed. On this basis, potential advancements and research topics regarding SHM systems based on flexible sensing technology for hydrogen storage tanks are discussed, and it is expected that flexible sensing technology will play a game-changing role in the future construction of SHM systems for hydrogen storage tanks. [Display omitted] • Flexible sensors are suitable for the SHM application of hydrogen storage tanks. • The sensor array and composite sensor-structure approaches are introduced. • Flexible piezoelectric transducers can provide guided waves with mode tuning. • Applying ultrasonic guided wave method to composite pressure vessels is limited. [ABSTRACT FROM AUTHOR]

The radial displacement of hydrogen storage composite overwrapped pressure vessel (COPV) is a key factor related to the collapse failure and burst pressure. However, there is still lack of effective method to monitor the radial displacement during the hydrostatic test and service process of the vessels. This paper proposed a method to measure the radial displacement based on fringe projection profilometry (FPP). Hydrostatic test with a composite overwrapped pressure vessel verifies the proposed method. The variation of displacement changing with inner pressures observed in the experiments is in agreement with that obtained from finite element analysis. Also Computed Tomography (CT) scanning is conducted and a widely spread micro defects is found in the composite layer of the cylinder. 78.9% of the total observed defects are small (<1000 mm2). In regions where large-sized defects (>1000 mm2) are concentrated, the total area of defects reaches 16,200 mm2. According to the statistical analysis, the strong correlation is found between the defects area and radial displacement. • Presented a novel method based on fringe projection profilometry (FPP) for monitoring the deformation of composite overwrapped pressure vessels (COPVs) during hydrostatic testing. • Employing 3D point clouds from FPP to reconstruct the cylinder and measure radial displacement. • The variation trend of radial displacement with pressure obtained by experiments is consistent with the finite element results. • Utilized Computed Tomography (CT) to detect and quantify micro delamination defects in the cylinders. • A significant correlation was found between the area of defects and radial displacement, while the relationship between the number of defects and radial displacement was less pronounced. [ABSTRACT FROM AUTHOR]

Styrene-butadiene-styrene block copolymer (SBS) modified bitumen (SMB) is unable to meet usage requirements after being exposed to sun-light, heat and oxygen. The researches show that it is difficult to restore bitumen effectively when the penetration of the aged bitumen is below 20 dmm. Therefore, the penetration of 20 dmm is taken as the dividing line in this paper. Higher than 20 dmm is considered as mild-moderate aging, while lower than 20 dmm is considered as severe aging. The traditional rotating thin-film ovens (RTFO) and pressure aging vessels (PAV) methods are similar to simulate the aging behavior of the upper layer of bitumen pavement, but they are difficult to simulate the aging in the depth direction of bitumen pavement. In this paper, the aging of the modified bitumen is simulated by extending the aging time and deepening the depth of the aging mold, and then it is graded according to the penetration. We aimed to investigate the differences in physical, microscopic and rheological properties of SMB with including 0 wt%, 1.5 wt%, 2.5 wt%, 3.5 wt%, 4.5 wt% and 5.5 wt% SBS content before and after aging. Through the physical performance, such as penetration, softening point, ductility and elastic recovery, it was observed that a high SBS content leads to strong anti-aging ability. Fourier Transform Infrared (FTIR), fluorescence microscopy (FM), scanning electron microscopy (SEM) and atomic-force microscope (AFM) revealed that a good network structure can be formed through absorbing light components when the SBS exceeds 3.5 wt%. After that, it was found that there is a positive correlation between aromatic index and penetration, as well as a positive correlation between butadiene index and softening point. Additionally, rheological frequency scanning and temperature scanning indicated that the modulus was increased and the phase angle was decreased with increasing SBS content or aging. After aging, the rutting resistance of SMB was enhanced but the cracking resistance was weakened. This research can establish a theoretical support and foundation for the regeneration of the mild-moderate aged SMB. [Display omitted] • The simple method for judging SMB aging degree is further improved. • The physical properties, microscopic properties and rheological properties of mild-moderate SMB are systematically studied. • The aging mechanism of SMB with mild-moderate aging is obtained, which provided a theoretical basis for regeneration. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis of conical components in pressure vessels emphasizing their significance when utilized to transition between different diameters or slopes. A thorough design and analysis are underscored as essential for ensuring the safety and reliability of these components under diverse loading circumstances. The paper aims to propose enhancements to the European Pressure Vessel Standards concerning conical components under internal pressure, with a focus on improving safety, reliability, and compliance with industry standards. Existing European standards are reviewed, identifying potential gaps and proposing practical solutions. The paper also presents research findings on the influence of cone apex angles, shell geometries and design pressure on cone plate thickness calculations. A new methodology for the design and analysis of conical components in pressure vessels is proposed, offering a potential pathway to safer and more efficient pressure vessels. A range of cylinder diameter between 1000 and 2500 mm and cone angles between 30° and 60° are used as input to quantify the difference in cone thickness for a design pressure ranging between 10 and 200 bar g. The proposed method yields results much closer to AD2000 compared to EN13445, leading to slightly thicker cones (up to 2.2 mm for the selected range of cone diameters and angles) compared to the former, resulting in safer pressure vessel design, and thinner cones (up to 22 mm) compared to the latter resulting in significant material savings. A comparative analysis was performed through Finite Element Analysis validating the EN13445 unsuitability for cone thickness calculations. A modification is proposed for equation (7.6)-(8) in EN13445 resulting in thinner plates reducing the cone plate thickness difference to 0.9 % on average compared to the current deviation of -9.6 % on average for the selected range of cylinder diameters and cone angles. • Enhancements to European Pressure Vessel Standards focusing on conical components under internal pressure are proposed. • A comparative analysis between AD2000 and EN13445 on cone thickness and design safety is presented. • Theoretical calculations are validated through Finite Element Analysis, highlighting discrepancies and areas for improvement. • Modifications to EN13445 are suggested to better align the Standard with practical outcomes and reduce excess material. [ABSTRACT FROM AUTHOR]

A large body of work has been conducted to investigate the embrittlement and degradation of reactor pressure vessel (RPV) steels. This includes experiments on alloys with different compositions, performed in research and test reactors and ion accelerators spanning various temperatures, fluxes, and fluences. In this paper, we perform a critical review of the published experimental data and compile experimentally reported values for dislocation loop size/density, precipitate size/density and yield stress into an easily downloadable format that can be used by both experimentalists and modelers. This thorough experimental review is complemented by a brief review of simulation efforts at atomistic and mesoscopic length scales. This paper highlights key aspects of the behavior of RPV steels under irradiation, identifies gaps or discrepancies in current understandings, and identifies future priority research directions. • Compiles largest database with experimentally reported values for dislocation loop size/density, precipitate size/density, and yield stress. • Articulates a list of data needs formulated by modeling teams. • Provides recommendations on critical experiments that can be done to validate modeling efforts. [ABSTRACT FROM AUTHOR]

The energy consumption of conventional 70-MPa hydrogen refueling stations (HRS) with liquid hydrogen (LH 2) pumps remains at a high level due to the low efficiency of LH 2 pumps working at extremely high pressures, up to nearly 90 MPa. This paper presents a novel HRS with significantly lower energy consumption, based on a step-by-step compression strategy enabled by a highly-efficient 50-MPa LH 2 pump for low-pressure compression and a subsequent thermal compression module for high-pressure compression driven by thermal energy. The performance of the cryogenic pressure vessels in the HRS process is analyzed via a numerical model, and then several improvements to the HRS process are proposed for large-scale refueling requirements. Finally, the techno-economic performance of the HRS is compared with the conventional HRSs and the HRS with pure thermal compression. Compared to the conventional HRSs with 90-MPa LH 2 pumps, the capital cost of the proposed 400-kg/day HRS is reduced to $1.52M from $1.80M, while its energy consumption is reduced to 0.3 kWh/kg H2 from 1.3 kWh/kg H2. This work provides a new solution for low-energy-consumption hydrogen refueling which would be beneficial for reducing the overall cost of the hydrogen supply chain. [Display omitted] • A novel hydrogen refueling station with pump and thermal compression is proposed. • The reliability of this HRS is higher in the high-temperature environment. • A pump can supply more refueling units to increase the capacity of the HRS. • Capital cost of the HRS is $1.52 M, which is much lower than conventional HRS. • Power consumption of the HRS with 50-MPa pump is only 0.3 kWh/kg of hydrogen. [ABSTRACT FROM AUTHOR]

Filament-wound Composite Pressure Vessels (CPVs) are employed largely for gas or fluid storage under pressure in aerospace, automotive and naval industries. Composite vessels are subjected to harsh conditions such as critical loadings, extreme temperatures, and bursting; therefore, a permanent in-situ and online monitoring approach for the structural integrity of the vessels is essential. Hence, this review paper focuses on the description of the most trending used sensors such as piezoelectric (PZT and PVDF), piezoresistive (BP and MXene) and fiber optic (SOFO®, OBR and FBG) sensors, for developing a Structural Health Monitoring (SHM) approach to create self-sensing composite pressure vessels. The novelty of this review paper lies in providing an overview of existing works covering the integration of sensors in composite vessels, including sensor types, localization, and their impact on composite integrity. Particularly, an analysis of the literature is provided concerning the sensor's integration and especially their monitored parameters, layout design and arrangement in CPVs. Additionally, the interaction between the host composite material and sensors is analyzed to understand how to integrate sensors with the minimum possible defects that alter the mechanical performance of composite vessels. Lastly, a discussion of a CPV's SHM system is provided to offer researchers a foundation for upcoming experimental work. [ABSTRACT FROM AUTHOR]

• The buckling behaviors of the corrugated shell under the same volume and weight are explored for the first time. • The coupling mechanism of corrugation shape parameters on buckling load was revealed. • The stiffness of the corrugated shells under uniform and concentrated pressure is verified from multiple angles. • It is inferred that reasonable non-uniform wall thickness can make more materials resist external loads. Cylindrical shells are easy to buckle under external pressure and need to be strengthened before they can be used in engineering. At present, the cylindrical shells are mainly enhanced by welding stiffeners inside them. However, for underwater pressure vessels, it is important to reduce the welding area. Some scholars have proposed various forms of corrugated shells, such as longitudinally corrugated shells, and studied the buckling behavior of corrugated shells under hydrostatic pressure. However, few studies have been conducted on such shells under the same weight conditions. Because an increase in the height of the corrugation necessarily leads to an increase in weight. So this reduces the comparability between the corrugated shells. The mechanism of non-uniform wall thickness on the improvement of shell material utilization is not explained. It is worth exploring how to achieve the best buckling performance under the limited weight. In this paper, the shape parameters of corrugations are explored, including the number, height and width of corrugations, and the coupling between them. The mechanical behavior of corrugated shell is studied from theory, FEA and experiment. In addition to hydrostatic pressure, the collapse of corrugated shells under concentrated pressure is also studied and comparative tests are carried out. The whole process of the collapse of the corrugated shell under concentrated pressure can be directly observed, and this is also an important performance index. In order to ensure the dimensional accuracy of the test samples, 3D printing technology was used for processing. In this paper, higher corrugations are not always better for the same weight. Because corrugation troughs tend to crack before buckling. This is like the short board effect, which requires collaborative optimization of peak and trough thickness. [ABSTRACT FROM AUTHOR]

• Developing of integral VVER1000 model using coupled code TRACE5-P05/PARCS with 3D neutron kinetics model. • Investigation of VVER 1000 integral model capabilities using coupled model of TRACE5-P05/PARCS with 3D kinetics. • Comparison of "Main steam line break" calculated results simulated by coupled 3D TRACE/PARCS code and 1D RELAP5 code. • Comparison between 3D TRACE/PARCS coupled code with 1D RELAP5 code are carried out and minor differences are investigated. This paper presents a comparative analysis of the Main Steam Line Break (MSLB) in a VVER-1000 reactor simulated with RELAP5 using Point Kinetics and the coupled code TRACE5-P05/PARCS using 3D kinetics. In the MSLB-scenario, it is assumed that the main steam line break of 580 mm inner diameter is located between the steam generator (SG) and the steam isolation valve (SIV), outside the containment. In a MSLB, a non-symmetric overcooling of the primary coolant takes place leading to a positive reactivity insertion. Hence, the main safety concern is to assess if the core may become critical despite SCRAM and it there is a considerable power increase (return-to-power). This paper will discuss the capabilities of different computational approaches to simulate the VVER-1000 plant behaviour during a MSLB; one approach based on 1D thermal hydraulics and Point Kinetics while the other one based on 3D thermal hydraulics of the reactor pressure vessel (RPV) and 1D thermal hydraulics for the remaining plant components based on a 3D neutron kinetics model. The analyses are performed for Beginning of Cycle (BOC) conditions i.e., with a fresh core loading when the plant is operated at nominal power. The neutron kinetic parameters for the RELAP5 Point Kinetics model were generated PARCS for the BOC assuming a boron concentration of 1630 ppm. The respective 2 energy group homogenized cross section libraries in PMAXS-format were generated by KIT using the SERPENT2 code. The investigations were performed in the frame of CAMIVVER-project, which focus was the assessment and development of reliable neutron physical and system thermal hydraulic models for safety evaluations of VVER-1000 reactors. The comparative analysis for the MSLB has shown that both applied codes are able to qualitatively predicts the plant behaviour under MSLB-conditions in similar manner. Differences are caused by the different approach to represent the core and RPV followed by RELAP5 and TRACE5.05/PARCS as expected. [ABSTRACT FROM AUTHOR]

This paper deals with the elastic/plastic buckling design of pressure vessels under external pressure loading. The objective is to build a simple analytical tool devoted to the elastic and elastoplastic buckling analysis of pressure equipments. This tool is aimed to provide the critical external pressure of cylindrical pressure vessels with ellipsoidal (or possibly hemispherical) heads. Depending on the geometry of the equipment and material parameters, the first buckling pressure may involve either the cylindrical shell or the closure ends, in the elastic or plastic range. The calculation tool will be thus based on a series of exact or approximate analytical solutions of the critical pressure of each part of the considered equipment. In this paper, the elementary shell structures involved in such pressure equipments are first individually examined. The fundamental critical pressures for each of them are recalled or introduced, both in elasticity and plasticity. The new solutions are validated against reference numerical results obtained through finite element computations. Then, approximate solutions of the critical pressure are derived for the same shells, taking account of specific boundary conditions (and not idealized ones, as before) due to the presence of the remaining part of the equipment. In the end, a VBA Excel software is developed. It is able to provide the mappings of the buckling mode type and the corresponding critical pressures for large ranges of geometric and material parameters in a very efficient way. These analytical solutions are finally confronted to numerical calculations performed on complete pressure equipments and they are shown to give quite reliable results. A discussion is also initiated on the use of such a program to update the current design rules in this scope of application. • Elastic–plastic buckling analysis of pressure equipments under external pressure. • Closed-form expressions brought together in an analytical tool. • A good agreement between analytical solutions and numerical finite element results. • Comparison to current design rules. [ABSTRACT FROM AUTHOR]

• Pixel-level defect depth detection is achieved, reducing the IR camera's infrared resolution requirements. • A defect detection model GADF-FcaNet-DDQ for uneven temperature rise and weak excitation conditions is proposed. • The infrared feature strategy containing the most defect information is screened out, and the 2D is completed by GAF. • The validity of the model in this paper is verified by comparing several time-series models with deep learning models. • The proposed model is a skeleton model with strong portability and expansion potential. The stepped eddy current thermography nondestructive testing technique has a low and uneven temperature rise under weak excitation conditions, which brings great challenges to the quantitative analysis of defects in the inner wall of pressure vessels. To solve the above problems, this paper proposes a multi-spectral channel attention residual network model based on a Gramian angular difference field (GADF) for automatic detection and quantification. Firstly, the noise reduction and compression of temperature time series data are accomplished by singular value decomposition and piecewise aggregate approximation. Secondly, three infrared feature strategies commonly used for quantitative analysis were transformed by GADF and Gramian angular sum field (GASF) techniques to filter out the infrared feature data sets that contain the most defective feature information. Finally, the frequency domainization of the feature map is realized by embedding the multispectral channel attention in the residual network. The global dependencies and relevant essential features of infrared data are effectively captured, and the redundant feature information generated by deep learning feature maps is suppressed. The effectiveness of the model is verified by comparing several time-series models with advanced deep-learning models. The results show that the proposed model has excellent performance in terms of accuracy, stability, and generalization ability. Meanwhile, the model can effectively extract the defects in the region of uneven temperature rise. [ABSTRACT FROM AUTHOR]

In nuclear reactors, the structural materials of reactor pressure vessel (RPV) are damaged by the radiation that produced by fission reactions. Neutron irradiation damage is one of the most critical factors for the degradation of the reactor pressure vessel (RPV). A displacement per atom (dpa) is a standard measurement for calculating neutron-and gamma-induced radiation damage in materials. The aim of this paper was to evaluate the neutrons radiation damage in the reactor pressure vessel of VVER-1200. In this paper, neutron damage factors, including fast neutron fluxes above 1 MeV, above 0.5 MeV, above 0.1 MeV, the damage rate (dpa/s), and Integrated damage [DPA for one effective full power year (EFPY)] were investigated for VVER-1200/AES-2006 reactor pressure vessel (RPV). The calculations are performed by using NJOY code together with the MCNP6 code at beginning of Cycle (BOC). The cross section library used in present calculations is based on ENDF/B-VII.1 library (ENDF71x). The NJOY code was used for generating DPA cross sections in an ACE formatted file that suitable for using in the MCNP6 code. The MCNP6 code was used for simulating the VVER-1200 reactor core and to calculate neutron DPA rates. MCNP6 simulation of the VVER-1200 reactor core identified the area where the RPV neutron radiation is maximized. The integrated damage for a full effective year was evaluated to be 2.128E-04 DPA/EFPD for the VVER-1200 RPV. • The evaluation of the neutrons irradiation damage in VVER-1200 reactor pressure vessel was performed by NJOY and MCNP6 codes. • Axial neutron flux and neutron spectra at inner surface and ¼, ½, and ¾ thicknesses of the RPV were calculated. • The peak flux on the RPV surfaces observed in the middle of core height, this region is called the belt-line region. • The damage rate and neutron flux were decreased from inner surface to the outer surface of RPV wall. • The integrated damage for a full effective year evaluated to be 2.128E-04 DPA/EFPD for the VVER-1200 RPV. [ABSTRACT FROM AUTHOR]

IVR-ERVC (In-Vessel Retention – External Reactor Vessel Cooling) is a critical accident management method for ensuring the integrity of the reactor pressure vessel (RPV) lower head. One of the most crucial aspects within this method is to enhance the CHF (Critical Heat Flux) on the outer surface of the reactor pressure vessel (RPV) lower head. This paper explores the application of graphene nanofluids in IVR-ERVC. This paper uses computational fluid dynamics to numerically simulate the CHF characteristics of graphene nanofluids under different undercooling, mass flow rate, concentration, tilt angle, and gap size conditions and analyzes the impact of different factors on CHF and the coupling effects between different factors. The undercooling range is 5 K–100 K, the mass flow rate range is 150 k g / (m 2 ∙ s) to 3000 k g / (m 2 ∙ s) , the concentration range is 0–1%, the inclination angle range is 0°–90°, and the gap sizes are 10 mm and 20 mm. The results show that the CHF can be effectively improved by adding nano-graphene into the base solution, and the CHF increases with the increase of subcooling degree, mass flow rate, concentration, dip Angle and gap size. Within the simulation range, the strengthening effect on CHF weakens when raising the undercooling and mass flow rate. And the larger the concentration and inclination angle within the simulation range, the better the enhancement effect on CHF. The maximum increase was 290%, while the average increase was 75.6%. This article studies the coupling effects between different parameters through numerical simulation. It can be concluded that increasing the mass flow rate weakens the enhancement of subcooling and concentration on CHF, increasing the subcooling weakens the enhancement effect of mass flow rate and concentration on CHF, and increasing the concentration enhances the enhancement effect of subcooling and mass flow rate on CHF. Enhance the mass flow rate will weaken tilt angle effect, while increasing the concentration will enhance the strengthening effect of tilt angle on CHF. [ABSTRACT FROM AUTHOR]

• NIOMOL 490 K steel belongs to the second generation of microalloyed steels. • Primarily intended for the manufacture of pressure vessels for operation at sub-zero temperatures. • Nil ductility transition temperature of the parent steel is −60 °C and of the welded joint is −40 °C. This paper is dedicated to the ductile–brittle transition behaviour of the microalloyed structural steel NIOMOL 490 K. This steel grade is used for welded pressure vessels subjected to dynamic loads and operating at sub-zero temperatures. Therefore, it must have an acceptable toughness. Due to its importance for the safety assessment of pressure vessels, a characterization of this steel was carried out using the Charpy V-notch impact test in the temperature range between −60 °C and + 60 °C. The notches were located in parent material, heat affected zone and weld metal. In this paper, the tensile strength properties at ambient temperature and the nil ductility temperature in the temperature range from −60 °C to + 60 °C are presented. [ABSTRACT FROM AUTHOR]

The aim of this paper is the multiscale investigation of composite pressure vessel structures wound with varying fibre tension. The paper explores the potential of "programming" the fibre tension force during the winding process of a high pressure hydrogen storage vessel. Two series of vessels were wound with two different tensions: Two series of vessels wound with forces of 3 N and 80 N respectively were experimentally investigated. Other technological factors, such as the type and weight of carbon fibre used, were kept constant throughout the study. Quasi-static burst tests were used to measure the elastic deformation of the vessel surface. Microscopic studies were also carried out to analyse the structure of the composite at different length scales. The fibre content, the geometric parameters of the voids and the distribution of the three main components of the composite – carbon fibre, technological defects and resin – were also determined. Representative RVE elementary cells were generated for both materials using statistical modelling. The composite was then homogenised and elasticity matrices were obtained for the fibre tensile forces in both materials. [ABSTRACT FROM AUTHOR]

Due to the uncertainty of structure and material parameters, reliability analysis of hydrogen storage composite pressure vessel (CPV) is an important issue. In this paper, reliability analysis of hydrogen storage CPV is carried out based on kriging surrogate model with two types of random-interval uncertainties. First, progressive failure behavior is analyzed based on finite element model (FEM) of CPV. Second, the kriging model is built to surrogate the burst pressure. Then, global sensitivity analysis is conducted using Sobol method. Finally, uncertainty analysis and reliability analysis of CPV are carried out with two types of random-interval uncertainties. The results show that longitudinal tensile strength, thicknesses of the hoop layers and the helical layers are important factors of the CPV burst. Besides, the reliability of CPV is low (0.048) with random-interval uncertainties, which should be improved to increase the safety of CPV. The proposed method provides a general solution to the reliability analysis of CPV with two types of random-interval uncertainties, which would co-exist in the hydrogen storage CPV. [Display omitted] • The kriging model of hydrogen storage vessel burst is established and verified. • The global sensitivity analysis of burst is carried out by Sobol method. • Longitudinal tensile strength and layer thickness are important influencing factors. • Reliability analysis is carried out with random-interval uncertainties. • Reliability is smaller with hybrid uncertainties than with only random uncertainty. [ABSTRACT FROM AUTHOR]

In zero-emission solutions for the hydrogen supply chain, high-pressure hydrogen storage in Type IV composite overwrapped pressure vessels (COPVs) is crucial for being safe and secure for a variety of stationary and transport applications. These COPVs consist of a polymeric liner material that works as a barrier for the stored hydrogen, while the carbon fiber-based composite provides the strength to hold the high-pressure hydrogen (of nominal working pressure more than 70 MPa to achieve the competitive driving range). Several experimental studies and simulation work have been performed on the viability of various polymers as low-permeability materials under low-pressure conditions. However, because of their proprietary nature and commercialized research, the characteristics of hydrogen permeation through polymers and their behavior at high pressure are still readily available in the literature. It is a major concern and the most crucial component of Type IV COPVs that these polymeric liners hold high pressure and maintain the necessary density of hydrogen (state of charge) toward operational requirements and safety concerns related to the cause of failures due to permeation (such as blistering, buckling, cracking, and so on). This paper investigates the role of polymeric liners on hydrogen permeation behavior using finite element modeling. For this, a UMATHT subroutine is developed within the Abaqus software to implement a new hydrogen permeation transport model with extended governing equations. Through the simulations and material modeling, the role of hydrogen transport properties (permeability, diffusivity, and solubility), structural characteristics (crystallinity, free volume, thickness) of plastic liners, and the role of operational parameters (concentration, pressure) are combined to validate the model from the experimental data in the literature to estimate the effective thickness required to maintain the permeation limit of the polymeric liner of 70 MPa Type IV COPVs. • A comprehensive review for polymeric materials is provided which are generally acts as liner material for high pressure hydrogen permeation barrier used in compressible high pressure hydrogen storage pressure vessels. • A mechanism of hydrogen permeation and exhaustive material model for polymeric liner material has been described to implement into Finite Element Analysis (FEA) using UMATHT a user subroutine. • Firstly, the investigation of material properties of HDPE polymer, geometry as representative volume element (RVE) of polymeric liner material of Type IV COPV for 2D sample with loading and boundary conditions described. • Then, the material model and all the FEA input implemented to validate the experimental published paper of Fujiwara et al. 2020, 2021 for HDPE material of thickness 1.5 mm and operating pressure up to 90 MPa. • The modeling framework of hydrogen permeation analysis considers the effect of pressure and concentration within the HDPE polymer sample with increasing thickness up to 5 mm that able to satisfy the permeation limit of hydrogen through the wall of 70 MPa Type IV composite pressure vessel (COPV). The hydrogen saturation inside the polymer has shown in terms of flux to evaluate the hydrogen transport properties through the polymeric liner material using time lag method. • The role of high-pressure cause compression of the HDPE polymer sample and corresponding crystallinity enhancement reported. • The results obtained from our study provide valuable insights into understanding the role of high-pressure hydrogen gas on the polymeric liner permeation behavior at various pressure. These insights can help determine their potential to model the complex behavior of hydrogen permeation modeling to evaluate the liner material permeation limit for 70 NWP of Type IV COPVs. [ABSTRACT FROM AUTHOR]

Filament winding (FW) technique determines the production efficiency of wound products and the bearing capacity of composite layers, so the development and innovation of winding technique and equipment have become the focus of scientific researchers. This paper analyzes the influence of fiber crossing on the composite layers in the single filament winding (SFW) technique, proposes a multi-filament winding (MFW) technique. Firstly, the constitutive model of fiber cross region is constructed from mesoscopic scale, and the influence of this phenomenon on the design of composite layers is illustrated using netting theory. Then, the MFW technique is designed and developed, and the three-point bending test of CFRP is carried out with digital image correlation (DIC) technology, indicating that the MFW technique exhibits superior flexural strength of 483.71 MPa. Finally, a 35 MPa type III vessel is taken as the object for comparative numerical simulation, the results show the stress adopting the MFW technique in the dome section is reduced by 1418 MPa, and is smaller and more evenly distributed in the cylinder section. The MFW technique takes full advantage of the CFRP properties, improves the pressure bearing capacity of composite layers, meets the American DOT-CFFC standard requirements, and reduces the carbon fiber usage. The lightweight design of high-pressure hydrogen storage vessels is realized with a novel idea, and the winding efficiency is greatly improved compared with SFW technique. [Display omitted] • The disadvantages of traditional filament winding technique are revealed. • Multi-filament winding (MFW) technique is proposed innovatively. • The theory of variable yarn thickness and variable yarn width is developed. • The composite layers with MFW technique have a better bearing performance. • MFW technique realizes lighter and more efficient manufacturing of pressure vessels. [ABSTRACT FROM AUTHOR]

• A chaotic mechanism was introduced to enhance bat optimization algorithm. • An inertial weight was set for the velocity to improve the ability of global exploration. • Extensive benchmark problems were used to verify the proposed method. In this paper, a chaos-enhanced bat algorithm is proposed to tackle the global optimization problems. Bat algorithm is a relatively new stochastic optimizer inspired by the echolocation behavior of bats in nature. Due to its effectiveness, it has been applied to many fields such as engineering design, feature selection, and machine learning. However, the classical approach is often prone to falling into local optima. This paper proposes an enhanced bat algorithm to alleviate this problem observed in the original algorithm. The proposed method controls the steps of chaotic mapping by a threshold and synchronizes the velocity of agents using a velocity inertia weight. These mechanisms are designed to boost the stability and convergence speed of the bat algorithm, instantly. Eighteen well-established and the state-of-the-art meta-heuristic approaches are considered to validate the effectiveness of the developed algorithm. Experimental results reveal that the proposed chaos-enhanced bat algorithm is not only superior to the well-established algorithms such as the original method but also the latest improved approaches. Also, the proposed method is successfully applied to I-beam design problems, welded beam design, and pressure vessel design. The results show that chaos-enhanced bat algorithm can deal with unconstrained and constrained feature spaces, effectively. [ABSTRACT FROM AUTHOR]

• Small scale results show realistic vessel opening compared to large scale. • High Speed Imaging (HSI) show Mach shock patterns along the BLEVE process. • Delay between vapor expansion and liquid boiling is visible through HSI. • Shadowgraphs show the shock formation process above the vessel. • A timeline of the BLEVE puts into perspective the physics involved in blast formation. The boiling liquid expanding vapour explosion (BLEVE) is well known but not well understood. Some still argue about what comes first, the BLEVE or the vessel rupture. Some believe the BLEVE is triggered by some pressure transient inside the vessel and this causes a superheat limit explosion which causes the vessel to rupture. Others believe it is the vessel rupture by some weakening process that leads to the BLEVE. This paper will provide evidence that the latter description that is correct for most, if not all BLEVEs observed in practice. This paper describes small scale experiments of aluminum tubes that were weakened by machining a thinned wall area over a specified length. The tubes were filled to a desired level with liquid propane and then the propane was uniformly heated electrically until the tubes failed. The failure pressures ranged from 10 to 33 bar. The tube was instrumented to capture failure characteristics (pressure, temperature) and consequences: blast overpressure and imaging of the propane cloud and shock around the vessel; ground force under it; transient pressure and imaging of the boiling process inside the vessel. The work was done to improve our understanding of the fluid – structure interactions during the fire heat induced failure of a pressure vessel holding a pressure liquefied gas. We were specifically interested in the near field hazards including blast overpressure and ground force. This paper will focus on the early milliseconds of the process where the vessel begins to open and a shock wave is formed and moves out into the surroundings. The imaging reveals presence of a Mach shock at the exit of the vessel at the early stage of the opening. A chronology of the event also shows that the lead shock is generated early in the explosion process, and is long gone before the liquid starts boiling, arguing that vapour expansion is the main contributor to the first shock overpressure. [ABSTRACT FROM AUTHOR]

Composite pressure vessels are highly promising components of solid rocket motor casing, yet it has long been plagued by burst risk of dome section. Although current advances via the addition of composite layers can enhance dome strength, the weight redundancy still restricts the lightweight implementation. To this end, this paper presents an innovative contour-driven collaborative design for dome section, which helps suppress burst risk and avoid redundant weight due to composite layer thickening. Numerical burst assessment reveals that the pole size engenders a failure competition between pole and equator, indicating that rational utilization of this competition paves a feasible way for dome reinforcement. Besides, the burst risk is further suppressed by collaborative design between polar opening radius, polar boss size, and aspect ratio of ellipsoidal dome. Notably, it is concluded that greater polar boss size effectively reduces the stress concentration near pole, and rational manipulation of dome aspect ratio ensures compatible deformation near equator. More interestingly, we offer a collaborative design methodology to reinforce dome with various polar opening radii without thickening composite layers. This unique contour-driven collaborative design opens new avenues for simultaneous implementation of burst risk suppression and lightweight construction of composite pressure vessels. [ABSTRACT FROM AUTHOR]

Damage monitoring during the service life of Type III composite overwrapped pressure vessels (COPVs) is crucial for ensuring their safe operation. This paper focuses on the damage localization in COPVs using ultrasonic guided waves structural health monitoring (SHM) techniques. Firstly, dispersion curves were plotted to establish a foundation for experiments and simulations based on the propagation theory of guided waves in multilayered anisotropic structures. Subsequently, a 3D finite element model of COPV was constructed to capture the propagation characteristics of guided waves within the COPV and their interaction with damage. The effects of different fiber angles and fiber layer numbers on guided waves propagation were analyzed, and their interrelationships were established. Furthermore, the "Wave Velocity Directionality" effect of the A 0 mode was identified during its propagation in COPV. The monitoring signals obtained from experiments were analyzed to assess the impact of damage on the time-domain and frequency-domain signals of guided waves. Finally, a damage localization algorithm based on mode-matching was proposed, and its localization accuracy was verified in COPVs with different damage locations and fiber layer numbers. The results demonstrate the significant potential of the proposed damage localization algorithm in the damage monitoring of COPV structures. [ABSTRACT FROM AUTHOR]

• Fracture toughness assessment of decommissioned reactor pressure vessel weld metal. • Use of miniature compact tension specimens to determine reference temperature. • Effects of thermal ageing and irradiation in weld metal are investigated. • Fractography is performed to gain insights into brittle crack initiation sites. This paper investigates the fracture toughness of thermally aged and irradiated weld metals extracted from head and beltline regions of a decommissioned nuclear reactor pressure vessel. Miniature compact tension specimens are fabricated from the thermally aged reactor pressure vessel head weld as well from the circumferential and axial beltline welds having fluences of 2.90 × 1016n/cm2 and 7.94 × 1017n/cm2, respectively. Master curve approach in accordance with the ASTM E1921 is applied to determine the reference temperature T 0 and it is found to be − 113.5 °C, −104.4 °C, and − 89.3 °C for the reactor pressure vessel head, axial beltline, and circumferential beltline welds, respectively. In addition, the multimodal reference temperature T m to assess the homogeneity of welds as well as key curve analysis for the quality assurance of testing are also provided. Fractographic analysis identified variations in crack initiation sites and microstructural inhomogeneities, particularly in the irradiated beltline welds. Overall, fracture mechanical testing of the materials demonstrated that miniature compact tension specimens are effective for characterizing the fracture toughness of limited surveillance weld materials, revealing differences due to irradiation and weld location. [ABSTRACT FROM AUTHOR]

• The Beam Line Vessel and its components are modeled by Solidworks, the vessel pressure distribution, and adsorption uniformity of the crysorption pump are analyzed by simulation using the Molflow software. • The performance of the south cryopump is tested experimentally using in-situ measurement method. • With the continuous injection of gas, the adsorption probability of the cryopump decreases, so the pumping speed of the cryopump will decrease. • Due to the limited capacity of cryopump adsorption, it is necessary to regenerate the cryopump near the maximum. The cryogenic vacuum system is an important subsystem of Comprehensive Research Facility for Fusion Technology Negative Neutral Beam Injector, which provides vacuum environment support for various experiments related to the beam generation and transport process. In the paper, a simulation and experimental study of the Comprehensive Research Facility for Fusion Reactor Negative Neutral Beam Injector (CRAFT NNBI) cryopump performance has been carried out. The Beam Line Vessel (BLV) and its components are modeled by Solidworks, the pressure distribution, gas molecular velocity distribution and adsorption uniformity of the crysorption pump in the BLV are analyzed by simulation using the Molflow software, at the same time, the performance of the south cryopump is tested experimentally using in-situ measurement method. The simulation results show that the average pressure near the Neutralizer is 8.5*10-3 Pa, the average pressure near the Electrical Residual Ion Dump (ERID) is 8*10-3 Pa, and the average pressure near the Calorimeter is 9*10-3 Pa. The adsorption percentage fluctuates around 12%, which indicates that single structure plays the function of adsorption efficiently, the theoretical pumping speed of the south cryopump on H2 was calculated to be 7.34*105 L/s, total theoretical pumping speed of two cryopumps can reach 3.67*106 L/s. The experimental results showed that when the south cryopump was operation, the pressures near the Neutralizer were 2.8*10-2 Pa, the pressures near the ERID were 2.7*10-2 Pa, and the pressures near the Calorimeter were 7*10-3 Pa, the actual pumping speed of the south cryopump on H2 was 6.37*105 L/s, total actual pumping speed of two cryopumps can reach 3.1*106 L/s. [ABSTRACT FROM AUTHOR]

The core design concept for Gas-cooled Fast Reactors (GFR) is currently under development. In this paper, the reflector design for the 75 MW refractory core of GFR demonstrator ALLEGRO has been improved. SiC, ZrC and Zr 3 Si 2 are considered as potential reflector materials, along with stainless steel (15-15Ti) for comparison. With the aid of Monte Carlo calculations, the neutronic performance of each material is evaluated with respect to criticality, power distribution, neutron spectrum, Doppler reactivity coefficient, burn-up, dpa of SiC cladding, and fast neutron flux on the reactor pressure vessel (RPV) wall. The results suggest that ZrC is the most suitable reflector material, offering the highest reserve reactivity, the flattest power distribution, relatively higher negative Doppler coefficients, the lowest reactivity loss rate of the core with burnup, and lower peak dpa damage. SiC is also an effective reflector material, but it causes very high pin power generation in the fuel rods facing the reflector due to significant thermalization of neutrons, challenging the reactor safety margin. Further analysis of the number of reflector rings and coolant volume fraction reveals that a four-ring reflector design appears to be a reasonable compromise between the core neutronic efficiency and minimizing the RPV dimensions. A coolant ratio of 20% is recommended based on conservative estimates of gamma heating and maximum temperature tolerable in the reflector. • Analyze the potential reflector materials for GFR refractory core design, including SiC, ZrC, and Zr 3 Si 2 , and 15-15Ti. • Present the model description of the ALLEGRO reactor core and perform neutronic calculations to examine reflector properties. • Investigate the influence of the number of reflector rings and cooling requirements arising from neutron and gamma heating. [ABSTRACT FROM AUTHOR]

• A boron-free SMR core is developed using coupled neutronics and sub-channel thermal-hydraulics tools. • Neutronics and thermal-hydraulics core characteristics are the focus of this paper. • Reactor safety related parameters are analyzed. • Code-to-code comparison is carried-out for the multiplication factor and nodal power. This work presents the safety-related neutronics and thermal-hydraulics features of a reactor core designed to fit into a Small Modular Reactor (SMR) moderated and cooled by light water. The core design process is conducted in an iterative manner to optimize its performance from safety perspective. The optimized core is operated without boron in the moderator and is characterized by enhanced safety features as a result of (1) avoiding concerns related to boric acid induced corrosion of a reactor pressure vessels internals; and (2) eliminating the probability of boron dilution accidents. The optimization studies are performed with an advanced multi-physics simulation tools including both neutronics (deterministic, Monte Carlo) coupled with a subchannel thermal-hydraulics code. With an intensive core design iteration process and through using such multi-physics tools, a reactor core with sufficient thermal margins, a cold shutdown margin, and a reduced power peaking factor is obtained. In this paper, the core design approach, core features, and the verification of the core analysis method are discussed in details. Finally, it has been concluded that the developed and optimized core fulfills all safety requirements and design objectives. [ABSTRACT FROM AUTHOR]

• The liner (metallic) elasto-plastic behavior. • The fibers elastic orthotropic behavior. • The matrix plastic anisotropic behavior to model the matrix cracking. In this paper we discuss the finite element modeling of Composite Overwrapped Pressure Vessels (COPVs) which are used in the aerospace industry, when high strength/weight ratios are required, for containers filled with pressurized fluids. The COPVs that we analyze are composed by a thin metallic liner and an external reinforcement made with high strength fibers that are wrapped around the liner embedded in an epoxy resin. It is shown in the paper that for a reliable description of the vessels behavior under internal pressure it is required to use a model that incorporates the mechanical behavior of the liner, of the fibers and of the resin matrix (micromechanical model). [ABSTRACT FROM AUTHOR]

The Master Curve approach allows the full characterisation of the ductile to brittle transition region (DBTR) of ferritic steels to be performed with a reduced number of tests. In this paper, the approach has been combined with the application of the small punch (SP) test. Modified SP specimens have been successfully employed to estimate the fracture toughness values of a pressure vessel steel and three structural steels. In addition, a methodology has been proposed, including a validity criterion for the performed tests. The estimated reference temperatures have been compared to the values obtained by means of full-scale conventional techniques. A unique simple relationship between both methodologies has been established for all the analysed materials. Therefore, this paper confirms the suitability of the small punch testing technique for the characterisation of the DBTR of several ferritic steels. It is a promising, simple and cost-effective test, which can be performed with simple equipment. • Small punch notched specimens can be applied to estimate the reference temperature. • A methodology to estimate the reference temperature has been proposed. • A single correlation has been obtained for the ferritic steels analysed. [ABSTRACT FROM AUTHOR]

This paper discusses the assessment of the WWER-1000 reactor pressure vessel integrity and the analyses performed to protect the irradiated vessel against brittle failure. The paper focuses on studies assessing the effects of base metal hardening on fast fracture evaluation results. It is shown that the results depend significantly on the material model used (elastic or elastic–plastic) as well as on the base metal mechanical properties (including or not the hardening produced by irradiation). Considering the change in tensile properties of the base material under irradiation may change the identification of the limiting combination of the pressurised thermal shock scenario, the limiting crack front point, and the crack aspect ratio. To demonstrate these effects, the results of the calculations performed for the South Ukrainian Nuclear Power Plant Unit 2 reactor pressure vessel residual lifetime are presented. • The problem of RPV lifetime evaluation is discussed. • The effects of base metal hardening on fast fracture evaluation are investigated. • The conservatism of the approach to the fast fracture evaluation is discussed. [ABSTRACT FROM AUTHOR]

Highlights • Assure structural integrity of NASA layered pressure vessels. • Apply ASTM E1820 and E1921 to toughness evaluations of legacy pressure vessel steels. • Apply E1921 inhomogeneity analysis to welds and weld heat affected zones. • Combine toughness properties from multiple vessels using E1921 inhomogeneity analysis. Abstract This paper describes testing conducted on dis-assembled layered pressure vessels to determine the fracture toughness properties of the component structural steels used in their construction. These vessels are part of a large number of similar vessels used at NASA laboratory facilities which were constructed during the 1950s and 1960s to support the then expanding space program. Fracture toughness properties are determined for the ferritic structural steels according to the ASTM standards E1820 and E1921 and the intention is to use the properties obtained from a small number of sacrificed vessels to assure the safety of the remaining vessels. This paper describes the NASA program briefly and the preliminary data obtained more extensively. The steels used to construct the vessels are no longer used in pressure vessel construction but are present in many structures that exist throughout the world that date from the same time period. The properties are hence important and useful beyond the more narrow NASA application. A discussion is also included on the applicability of the modern ASTM fracture toughness tests to evaluate the fracture toughness properties of these early high strength pressure vessel steels. [ABSTRACT FROM AUTHOR]

Abstract The safety and reliability of large-scale structures such as pressure vessels are related to a number of uncertain factors, including the load and the size of their initial cracks. This study carries out probabilistic fracture mechanics analyses of pressure vessels that contain defects under the coupling of inertial force and internal pressure. Based on the weight function, this paper provides an integral expression for the stress intensity factor (SIF) of the crack front and then estimates the SIF that meets the engineering accuracy requirements. Considering the fracture toughness criterion, K IC , based on linear elasticity as the failure criterion, the Monte-Carlo method is used to calculate the failure probability of the pressure vessel cylinder, with the fracture toughness of materials, crack depth, and load as random variables. This method can provide a point of reference for fracture calculations and reliability analyses of pressure vessels. Highlights • The pressure vessel not only subjects to the uniform internal pressure, but also the inertial force. • Based on the weight function, the paper gives the SIF integral expression of the crack front and then estimates the SIF. • The failure analysis is carried out based on the probabilistic fracture mechanics method. [ABSTRACT FROM AUTHOR]

In the frame of the safety studies for the EU-DEMO reactor, attention is paid to the hydrogen concentration in the vacuum vessel and connected volumes since it would lead to a possible hazard of releasing tritium and activated dust. The risk of explosion cannot be excluded a priori if H 2 stockpiles. For this reason, in both water (WCLL) and helium (HCPB) cooled breeding blanket concepts of EU-DEMO, the problem is under investigation with a cross-reference between the available technologies in fission (such as the Passive Autocatalytic Recombiners – PAR) and fusion application. In particular, the recent analyses pointed out the implementation of the PARs into the Vacuum Vessel Pressure Suppression System or linked systems. This paper evaluates the Hydrogen behavior (main mobilized tritium source term) for the Helium-Cooled Pebble Bed (HCPB) VVPSS concept. The analyses preliminary investigate the stratification of the hydrogen mass inventory inside the PSS. In particular, a MELCOR 1.8.6 model of the PSS, based on past activities aimed at dust transport and thermohydraulic analyses, is adopted. The paper also introduces the applicability of PAR technology in the operation range of fusion devices, analyzing the problem of the recombination rate due to the dilution of Hydrogen after a Helium blowdown. [ABSTRACT FROM AUTHOR]

The use of Reverse Osmosis (RO) process in seawater desalination to provide high-quality drinking water is progressively increased compared to thermal technologies. In this paper, multistage spiral wound RO desalination process is considered. Each stage consists of several pressure vessels (PVs) organised in parallel with membrane modules in each PV being organised in series. This allows disconnecting a set of PVs and membrane modules depending on the requirement of cleaning and maintenance. While this flexibility offers the opportunity of generating several RO configurations, we presented only four such configurations of the RO system and analysed them via simulation and optimisation. Production of different grades of water catering different needs of a city is also considered for each of these configurations. The optimisation has resulted in the optimal operating conditions, which maximises the water productivity and minimises the specific energy consumption of the proposed configurations for a given water grade in terms of salinity. For instance, the results indicate that the proposed RO networks can produce drinking water of 500 ppm salinity with a minimum specific energy consumption of 3.755 kWh/m3. The strategy offers the production of different grades of water without plant shutdown while maintaining the membrane modules throughout the year. • Flexible design, operation and maintenance of RO desalination process proposed. • Proposed design is capable of producing different grades of water. • Operation parameters are optimised giving minimum energy consumptions. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for estimating the minimum design vapor pressure of prismatic pressure vessels for on-ship application. Engineering authorities guide the codes for a novel concept design such as a prismatic pressure vessel using a design by analysis (DBA). DBA methods enable high efficiency because they directly calculate the loads to avoid inherent conservativeness that exists in a design by rule (DBR). However, in DBA methods, the designer should conduct a finite element analysis (FEA) and evaluate the results iteratively to meet the design criteria. In this paper, we propose a new approach to estimating the minimum vapor pressure of a prismatic pressure vessel that follows the design philosophy of an IMO Type C independent tank. The procedure of the proposed method was demonstrated based on a case study. An FEA was also conducted for verification purposes. The results show that the proposed method can effectively estimate the required minimum shell thickness and designed vapor pressure without conducting an iterative FEA. In addition, minimization of the tank shell thickness is made possible because the proposed method directly calculates the crack propagation rate to avoid an unnecessary margin while satisfying the fatigue crack propagation criteria. [ABSTRACT FROM AUTHOR]

This paper investigates the minimization of the diameter of wire-wound pressure vessels. The study is conducted in two stages. Firstly, the stresses arising from the wire winding of the vessel and the internal pressure application are extracted based on the distortion energy theory. It is assumed that the equivalent stress within the winding area in each layer, under the internal pressure condition, equals the allowable stress of the wire, and in the cylinder area, it does not exceed the allowable stress of the cylinder. The required number of layers and the wire tension during winding (two essential unknown parameters in the industrial winding process) are determined to satisfy these assumptions. In the second stage, the diameter optimization of the vessel is studied using the Distortion Energy (DE) theory. It is found that reducing the cylinder diameter results in a decrease in the vessel diameter. The occurrence of buckling or yielding in the cylinder is a limiting constraint for reducing the cylinder diameter. For validation, the results obtained from the derived equations are compared and confirmed against finite element results and the equations provided in the ASME code. Wire-winding simulation around the cylinder uses the element birth and death technique. The agreement between the derived equations and the code equations, as well as finite element results, is excellent. In the examined case study, using the DE theory leads to a 24 % reduction in wire consumption compared to the maximum shear stress (MSS) theory. In the optimization stage, the vessel weight is further reduced by 24 %. Compared to monobloc shells, the optimized wire-wound vessel weight based on the DE theory experiences a 77 % reduction. • Minimization of Wire-Wound Pressure Vessel Diameter Based on Distortion Energy Theory. • Using Element birth and death technique to simulate winding process. • Computing required layer number and winding stress to use all capacity of material. • Validation of derived equations with ASME code formulas. [ABSTRACT FROM AUTHOR]

The paper is devoted to a sandwich cylindrical pressure vessel with hemispherical and superellipsoidal dished heads loaded with external uniformly distributed pressure. The distinguishing feature of this sandwich structure is an individual functionally graded core. The strength and buckling problems are numerically FEM studied in the linear range. The calculations are carried out for vessels with aluminium faces and aluminium foam core. As a result stress distributions along the meridian and through the thickness of the shell have been generated as well as the buckling modes and buckling loads. Based on the obtained plots it is seen that the stress distribution is more favourable for the tank with superellipsoidal head especially when the shear stress in the core is considered. Moreover, the distribution of shear stress through the thickness of the tank changes considerably depending on the part of the tank in which it is measured. • Functionally graded mechanical properties of the core are introduced. • Dished head in the form of superellipsodial shell is proposed. • Shear stress through the thickness vary considerably depending on the point measured. • The edge effect can be diminished by application of superellipsoidal dished head. [ABSTRACT FROM AUTHOR]

Studying the typical accidents of nuclear power plant is the basis of nuclear power plant design. In a previous study, our research team proposed a suppression containment system based on the HPR1000 and discussed its performance under the Large-Break Loss-Of-Coolant Accident (LBLOCA) scenario. During the LBLOCA, the activation of the Passive Safety Injection System (PSIS) ensures the core integrity. However, the effectiveness of the Passive Cavity Injection and cooling System (PCIS) in dealing with the extreme accident condition is not adequately confirmed and analyzed. In addition, the rapid depressurization of the Reactor Pressure Vessel (RPV) under LBLOCA does not allow for a full verification of the fit between the PSIS and the Automatic Depressurization System (ADS). Hence, this paper examines the response of the HPR1000-based suppressive containment system in the event of the Small-Break Loss-Of-Coolant Accident (SBLOCA) and the Station Blackout (SBO). We employ the accident analysis procedure, with a specific focus on the thermo-hydraulic evaluation of the PCIS, the PSIS and the ADS. The results show that, the HPR1000-based suppressive containment system has the ability to handle the SBLOCA and the SBO. The PSIS and ADS work together to effectively inject water into the reactor core during the SBLOCA. The start-stop logic setting of the system is reasonable and effective, ensuring long-term cooling of the reactor core. During SBO condition, PCIS effectively achieves rapid cooling of the lower head, ensuring that the peak temperatures do not exceed 600 K. This prevents the lower head from experiencing failure due to high temperatures. Furthermore, the maximum pressure within the containment is a mere 324 kPa, much below the design pressure of 520 kPa. This guarantees that the containment pressure remains within an acceptable range throughout the whole accident. [ABSTRACT FROM AUTHOR]

In-Vessel Retention (IVR) is designed as one of the key mitigation strategies for Chinese Advanced Passive pressurized water reactor (CAP1400), to keep melt corium retaining in reactor pressure vessel (RPV) under severe accidents situations. External Reactor Vessel Cooling (ERVC) is selected as the main measure to achieve the purpose of IVR. The key safety evaluation criteria for the effectiveness of IVR is that the heat flux on the RPV outer wall surface is less than the Critical Heat Flux (CHF). In order to investigate the CHF limit values, the relevant experimental projects had been conducted for CAP1400 plants, and we obtained the preliminary data. However, the CHF limit values are influenced by many factors, but current researches about these factors are not enough. Based on the full-height experimental facility, we conducted the CHF experiments, it is found that the system pressure, the surface characteristics of RPV (e.g. surface aging, etc.), different heat flux distributions, above 90° heating could have different influence on CHF limit values. In this paper, the experiment results and the preliminary analysis of these different influence factors are given. In these factors, some influence is complicated, for the factor of system pressure, there are two aspects of influence, and the overall enhancement of CHF limit values is about 10%, and for the surface aging effect, the experiment results show that the surface aging effect can enhance CHF limit values by more than 15%. [ABSTRACT FROM AUTHOR]

Vehicles that are powered by gaseous fuel, e.g., compressed natural gas (CNG) or hydrogen (H 2), may, in the event of fire, result in a jet flame from a thermally activated pressure relief device (TPRD), or a pressure vessel explosion. There have been a few incidents for CNG vehicles where the TPRD was unsuccessful to prevent a pressure vessel explosion in the event of fire, both nationally in Sweden and internationally. If the pressure vessel explosion would occur inside an enclosure such as a road tunnel, the resulting consequences are even more problematic. In 2019 the authors investigated the fire safety of CNG cylinders exposed to localized fires. One purpose of the tests conducted in 2021 reported in this paper is to investigate whether extinguishment with water, e.g., from a tunnel deluge system, may compromise the safety of vehicle gas cylinders in the event of fire. Steel cylinders handles the situation with localizde fire and/or cooling with water well. Composite tanks can rupture if the fire exposure degrades the composite material strength, and the TPRD is not sufficiently heated to activate, e.g., if the fire is localized or if the TPRD is being cooled by water, which prevents its activation. • The article reports on 15 fire and extinguishment tests (i.e., uneven heating and cooling) of CNG and hydrogen cylinders. • The article investigates the risk of pressure vessel explosion and the characteristics of jet flames from TPRDs. • The article finds that steel cylinders are robust against fire exposure and water cooling. • The article finds that composite cylinders may leak gas through the damaged material or fail to activate the TPRD. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mixed-mode I&II FCG tests are conducted on 16MND5 steel using CTS specimens. • Crack driving force and crack closure both have significant impacts on the FCG curves. • Fatigue fractography reveals similar microscopic features in the Paris region for all CTS tests. • A unified method for characterizing FCG rates is developed. Although numerous fatigue crack growth (FCG) tests have been conducted, the conclusions drawn regarding the mixed-mode FCG rate are inconsistent and even contradictory. A reasonable conjecture is that crack driving force and crack closure effects may play a crucial role in causing this situation. In this paper, the 16MND5 steel, commonly used reactor pressure vessel (RPV) steel, was employed to investigate the mixed-mode I&II FCG behaviors through the compact-tension-shear (CTS) experiments. The influence of crack driving force and crack closure effect was analyzed and discussed. The results show that the crack propagation path tends to maximize the tangential stress component at the crack tip, and the effect of Δ K II can be negligible once the Paris region is reached. Moreover, when considering the crack closure corrected Δ K I , named Δ K I eff , all the FCG rate data under different loading conditions can be collapsed into a narrower band of distribution. The premise for arriving at this result is to use the stress intensity factors solution that are applicable to specimens with real slanted propagating cracks, rather than applying equivalent methods based on single-edge straight crack assumptions. Finally, the fatigue fractography further confirms that the FCG mechanism during the Paris region all follow a similar quasi-mode I behavior. [ABSTRACT FROM AUTHOR]

The paper presents a detailed description of the oil rectification process used in upstream oil and gas plants, including the significant equipment involved. One such equipment highlighted in the study is a pressure vessel utilized as a separator to separate the liquid and gas phases. This pressure vessel has been in operation for over two decades. A thorough examination of the mentioned pressure equipment was conducted during the process evaluation. It was discovered that the internal side of the vessel, particularly its back elliptical head, had suffered extensive damage due to erosion and corrosion, emerging as the most significant cause of the deterioration. The application of RBI-estimation revealed that the vessel falls under the category of highly risk equipment, and there is a significant risk of both environmental and financial consequences associated with its potential failure (leakage). Such failure is anticipated to occur promptly in the area below the wear plate of the vessel's nozzle. • Separator is specifically designed to carry out a three-phase separation. • Damage mechanisms are corrosion, erosion, MIC, cracking. • NDT, corrosion rate and remaining life of the vessel refer to urgent sanation. • RBI methodology revealed that the vessel falls under the category of highly risk. [ABSTRACT FROM AUTHOR]

A methodology to develop a 3D Finite Element (FE) model of a full metal-lined Composite Overwrapped Pressure Vessel (COPV) was developed and is presented in this paper. The model is intended for prediction of the metal-composite delamination and residual dent depth developed in the metal liner as a result of quasi-static indentation loading. Cohesive elements are used to model the composite and the metal-composite interfaces. Experimental and numerical comparisons of force–displacement curves, delamination area and residual dent depth are presented. Numerical results are in good agreement to the experimental data. • A methodology for developing a 3D FE model of a full metal-lined pressure vessel is presented. • The FE model showed reliable correlations between simulation and experimental results. • The developed methodology is suitable for exploring design optimization and cost reduction. [ABSTRACT FROM AUTHOR]

Biogas upgrading is a vital step to produce high quality fuel called biomethane with above 90% methane (CH 4 ). Among the various technologies available for biomethane production, water scrubbing is the most extensively implemented technology around the world. However, during the process of biogas upgrading, a some amount of CH 4 is separated as CH 4 loss through the water flowing out of the water scrubbing column. In this paper, various factors affecting CH 4 loss from water scrubbing method are analysed. Some factors such as pressure, water flow rate and CH 4 concentration in input gas are dependent upon the solubility and partial pressures of the gases are generally known. Apart from these factors CH 4 losses due to bubble entrainment due to high pressure difference between water scrubbing column and desorption tank and gas short circuiting of the gas through the bottom section of the column due to no water sealing and water level maintencence also contribute to CH 4 losses. Therefore, CH 4 losses during the water scrubbing process due to these factors have been experimentally studied in this paper. A pilot scale water scrubbing system for biogas upgradation was used for the study. It was observed that CH 4 % (v/v) in the upgraded biogas and CH 4 loss % from the desorbed gas increased with the increase in pressure and increase in the concentration of CH 4 in the input gas. Increase in water flow rates caused removal of larger quantities of water containing more absorbed CH 4 and CO 2 from the scrubbing column, thereby increasing CH 4 loss of the system. Highest CH 4 loss % of 9.9% (±0.1%), was obtained with raw biogas sample when water was desorbed at atmospheric pressures in the desorption tank, i.e. when pressure difference between the water scrubbing column and desorption tank was highest. A pressure vessel was installed in between scrubbing column and desorption tank to reduce the pressure difference for water leaving the column by varying the pressure in the pressure vessel from 1 to 9 bar. With the increase in pressure in the pressure vessel, the pressure difference for water decreased which led to a saving in overall CH 4 loss of the system. Water sealing and water level maintenance in the bottom section of the column also affected CH 4 losses of the system. All the factors discussed in the article contribute to the CH 4 losses from the scrubbing column and cannot be solely credited to a single factor. [ABSTRACT FROM AUTHOR]

During the process of erecting a vertical pressure vessel from a horizontal to vertical orientation (0°to 90°) using tailing lugs, it is necessary to use a tailing lug with low local stress around the lug–shell attachment to prevent damage to the vessel shell during the lifting process. Two methods of local stress analysis, WRC-537 bulletin and FEA using ASME BPVC Section-VIII Division-2 are studied and evaluated in this paper. The WRC-537 method, which is known for being conservative, produced higher stress values compared to the FEA solution. This paper also examined the impact of various dimensional parameters related to tailing lug size and shape on local stress around the lug–shell attachment. In cases where single lug configurations fail to achieve the minimum required local stress values, paired lug configurations are purposed as a possible alternative solution towards reduced local stress. This paper also discusses the benefits of paired lug configurations over single lug configurations regarding the lower localized stress, especially for vessels with thin shells and large diameters. Paired lug configurations are found to have about four times lower localized stress compared to single lug configurations. When comparing rectangular and circular attachments, this study has found that rectangular attachments tend to have lower localized stress. • Evaluation of local stresses in the lug–shell attachment for various tailing lug configurations attached to a vertical pressure vessel. • Study of possible application of paired lugs as tailing lugs in comparison to single lug configurations. • Comparison of results obtained from WRC-537 and FEA methods for local stress evaluation. [ABSTRACT FROM AUTHOR]

The method for assessing residual life and disposable residual life of the material of Cr-Mo-V low-alloy cast steel elements after long-term service under creep conditions is presented in the paper. The research included performing the tests, in literature referred to as the short-term creep tests, at the constant level of stress of the test corresponding to the operating one and, at the temperature higher than the preset design one, as well as the creep tests with and without the measurement of elongation during the test. The test results presented in the paper confirmed the possibility of applying the short-term creep tests and the tests with elongation measurement in order to determine the time of further safe service of the material of elements after long-term operation made of low-alloy Cr-Mo-V cast steel types. [ABSTRACT FROM AUTHOR]

This paper will show that a simple membrane (e.g. balloon) is not always the minimal mass pressure vessel. Of course one could always add cables to support the membrane, or plate, to reduce the thickness and hence mass required of the membrane. By minimizing the sum of the mass of the membrane plus the mass of the cable network, a minimal mass solution for the pressure vessel can be found. We will show the necessary and sufficient conditions (involving material choices and cable network topology) for which a composite system, composed of a membrane and cable network, has less mass than a membrane alone. The main motivator for this study is a spin-stabilized pressurized space structure useful for artificial gravity habitats. To contain and support the membrane, we will optimize the topology of the class of prestressable structures called tensegrity. These structures are usually composed of a network of axially-loaded compressive and tensile members. In the pressurized examples of this paper, inflation provides the compressive forces, and hence the optimized tensegrity topology eliminates the compressive structures when they are not needed. The minimal mass designs herein produce easily-tunable prestressed networks, and control systems that allow deployment and stiffness tuning features. The minimal mass design of those structures, for different load combinations (pressure loads and centrifugal loads), produces a composite structure composed of membranes and cable network. Two different composite systems are analyzed and compared with simple uniform membranes: the first system is composed of a cylindrical membrane supported by circular ring cables, the second system is composed by a membrane surrounded by ring cables and longitudinal cables. The comparison of the minimal mass designs with the single continuous membrane clearly highlights the advantage of the composite systems made of high-performance materials. When the material of the membrane and cables are the same, there is no advantage to the composite system, but various requirements usually demand different properties of the membrane and cable material. [ABSTRACT FROM AUTHOR]

• The Master Curve approach has been successfully employed, combined with the use of mini-CT specimens made from two different reactor pressure vessel steels: ANP-5 and A533B LUS. • This paper adds further validation of the use of mini-CT specimens to define the T 0 of unirradiated RPV steels with relatively high values of this parameter. • A fractography analysis of the fracture surfaces was performed confirming the existence of cleavage fracture following the weakest link theory (i.e., one single initiation point), as required by the Master Curve approach. • A literature review was conducted to compare the T 0 values obtained with large conventional specimens with those obtained using mini-CT specimens. The safe operation of nuclear plants requires an accurate characterization of the fracture toughness of reactor pressure vessel materials, which can be reduced over time due to irradiation or thermal aging processes. This necessity is a challenge itself since the availability of specimens inside the surveillance capsules of the vessels is generally scarce. Therefore, innovative techniques have to be applied, in order to increase the reliability of fracture toughness measurements and at the same time to reduce the volume of material needed for the tests. In this paper, the Master Curve (MC) approach has been employed, combined with the use of mini-CT specimens made from two different reactor pressure vessel (RPV) steels (ANP-5 and A533B LUS). The MC methodology allows the fracture toughness of the material to be evaluated by using a single parameter: the reference temperature, T 0. This parameter has been previously estimated using mini-CT specimens in a number of unirradiated steels, most of them with relatively low T 0 values (-120 °C to −60 °C), providing satisfactory results. This paper adds further validation of the use of mini-CT specimens to define the T 0 of unirradiated RPV steels with relatively high values of this parameter. Additionally, the analysis of the fracture surfaces confirms the existence of cleavage fracture following the weakest link theory (i.e., one single initiation point), as required by the Master Curve approach. [ABSTRACT FROM AUTHOR]