Outer Container Research Articles

Optimizing neutron shielding: A specialised container approach for Disused Sealed Radioactive Sources and orphan neutron emitters

Shielding Disused Sealed Radioactive Sources (DSRSs) and orphan neutron sources, such as 252Cf, pose challenges due to the high penetration of neutrons, induced radioactivity in shielding materials, and the limited availability of compact, effective shielding materials. This study addresses these challenges by proposing a specialized container for the safe transport, conditioning, and disposal of neutron-emitting DSRSs and orphan sources. The computational tool that was used in this study is the Monte Carlo N-Particle (MCNP). The investigation begins with an examination of moderation materials, including high-density polyethylene (HDPE), paraffin, and water-extended polyester (WEP). Subsequently, four concrete types, namely Ordinary, Barite, Portland, and Serpentine Concrete, are scrutinized. Employing a comprehensive methodology, the design of the container is optimized to effectively moderate and absorb neutron emissions. The findings of this study demonstrate that the designed compact container can safely handle activities exceeding those studied, effectively managing up to 10 μg (about 0.2 GBq) 252Cf without exceeding 25 μSv/h at the outer container contact. This suggests a promising solution for the secure management of high-activity neutron-emitting sources.

The Immigration–Crime Nexus: Inner and Outer Containment Buffer or A Push Toward Delinquency

The ongoing debate over the immigration–crime nexus has continued to attract a wide range of research efforts in the criminal justice field. To build on these initiatives, this study not only examines the relationship between immigrants and adolescent crime but also explores attributes derived from containment effects that may contribute to or shield individuals from deviant behavior in America. Results showed that both immigrant and native-born adolescents share similar external attributes rather than internal traits that affect delinquency. For instance, inherent immigration status and identity is relatively more influential on self-reported substance problems among immigrant youth compared to their native-born counterparts. Interestingly, among external attributes, immigrant and native-born adolescents are responsive to legitimate opportunity and neighborhood order in different ways which thrust them into different deviant pathways.

Local structural behaviour of the outer containment of an NPP against hard missile impact

An aircraft crash and missile impact on a nuclear containment structure is currently described as an event beyond design basis; however, soon, it will be qualified as a primary design criterion. In the present study, the structural and dynamic behaviour of the outer containment of a nuclear power plant (NPP) has been studied to substantiate its structural integrity against the rigid missile impact. Scaled experiments (at a 1:4 and 1:3 ratio with respect to shell thickness) have been performed to study the localized behaviour of the containment structure against 10 and 20-kg rigid steel projectiles. The reinforced cement concrete (RCC) targets of thicknesses 150 and 200 mm have been subjected to impact at incidence velocity close to the landing and taking of velocity of the aircraft. The flexural reinforcement ratio was considered 1.25 % for a 150 mm thick target and 1.53 % for a 200 mm thick target. The effect of shear reinforcement on the penetration and perforation resistance has been studied for a 200 mm thick RCC target. A detailed post-test examination was conducted to evaluate the localized physical damage characteristics such as spalling and scabbing of concrete, penetration, perforation, crack propagation, and the damage induced in both flexural and shear reinforcements. The mechanics of deformation and failure modes of the target were investigated under varying incidence velocities, 60–115 m/s. The reinforcement characteristics under dynamic loading, such as strain time histories, strain rate sensitivity, and dynamic material properties, were also investigated. The presence of transverse reinforcement in 200 mm thick targets improved the ballistic performance by 12.50 %. Furthermore, the transverse reinforcement also played a crucial role in restricting the bending of the rear face flexural reinforcement and controlling the rear face damage propagation.

Evaluation of the effect of rotational speed and rheological nature on heat transfer of complex fluid between two cylinders

This paper presents numerical results for flow behavior between a cold inner cylinder and a hot outer cylinder. Both cyl-inders are placed horizontally. The space separating the two compartments is completely filled with a fluid of a complex rheological nature. In addition, the outer container is subjected to a constant and uniform rotational speed. The results of this work were obtained after solving the differential equations for momentum and energy. The parameters studied in this research are: the intensity of thermal buoyancy, the speed of rotation of the outer container and the rheological nature of the fluid. These elements are expressed mathematically by the following values: Richardson number (Ri = 0 and 1), Reyn-olds number (Re = 1 to 40), power-law number (n = 0.8, 1 and 1.4) and Prandtl number (Pr = 50). The results showed that the speed of rotation of the cylinder and the rheological nature of the fluids have an effective role in the process of heat transfer. For example, increasing the rotational speed of the enclosure and/or changing the nature of fluid from shear-thickening into shear-thinning fluid improves the thermal transfer rate.

Cylindrical Steel Tanks Subjected to Long-Duration and High-Pressure Triangular Blast Load: Current Practice and a Numerical Case Study

This paper presents an investigation into the design of ammonia tanks for long-duration and high-pressure blast loads. The focus is on cylindrical steel tanks that apply as outer pressure-tight containers for double-walled tanks storing refrigerated liquefied gases. Based on limited empirical data, it is known in the tank industry that these tanks can withstand an explosion pressure up to a peak overpressure of approximately 10 kPa and 100 ms positive load duration. However, there is a growing need to design tanks for higher peak overpressures in order to establish a higher safety standard and accommodate unforeseen future requirements. This paper explores the concept of adapting established steel tank designs to handle high-pressure and long-duration overpressure due to blast events. Numerical analysis is conducted on a representative steel tank geometry subjected to a triangular blast load of 30 kPa with a 300 ms positive load duration. Various load application and calculation options are analyzed numerically. Considering the challenging nature of analyzing tank structures under blast load, the paper addresses controversial aspects discussed in the literature and presents a suitable analysis concept for a deflagration blast scenario for cylindrical tanks. The results provide insights into the expected structural behavior of the tank under high-pressure and long-duration overpressure. The main finding is that the calculation method developed in this study demonstrates the feasibility of utilizing steel tanks in scenarios involving long-duration and high-pressure blast loads. Furthermore, the paper provides recommendations to guide future studies in this area. The findings have implications for the design and construction of tanks in critical infrastructure and offer valuable insights for engineers and researchers in this field, improving safety standards and ensuring adaptability to future utilization concepts.

Design and dynamic analysis of transport cask for SMR fresh fuel assembly

Transportation of fresh fuel assemblies requires the utilization of transport casks to ensure the internal radioactive material does not affect the environment. In this work, we introduce an innovative design of a transport cask for the fresh fuel assembly of a Small Module Reactor (SMR). The cask is constituted by two containers, supports and various energy-absorbing structures welded at the outer container. The structural integrity of the transport cask under variant scenarios determined by the International Atomic Energy Agency (IAEA) and domestic regulations was numerically evaluated. The detailed 3D model of the cask was created, and the simulations were performed via the Finite Element Method (FEM) using commercial software ABAQUS. Simulation results obtained from static and dynamic analyses indicated that the integrity of the designed transport cask can be assured during normal and accident conditions. The most severe damage during the 9 m drop tests was caused by a horizontal oblique condition and this configuration is recommended to be tested in future experiments.

3D printed non-uniform anthropomorphic phantoms for quantitative SPECT.

A 3D printing grid-based method was developed to construct anthropomorphic phantoms with non-uniform activity distributions, to be used for evaluation of quantitative SPECT images. The aims were to characterize the grid-based method and to evaluate its capability to provide realistically shaped phantoms with non-uniform activity distributions. Characterization of the grid structures was performed by printing grid-filled spheres. Evaluation was performed by micro-CT imaging to investigate the printing accuracy and by studying the modulation contrast ([Formula: see text]) in SPECT images for 177Lu and 99mTc as a function of the grid fillable-volume fraction (FVF) determined from weighing. The grid-based technique was applied for the construction of two kidney phantoms and two thyroid phantoms, designed using templates from the XCAT digital phantoms. The kidneys were constructed with a hollow outer container shaped as cortex, an inner grid-based structure representing medulla and a solid section representing pelvis. The thyroids consisted of two lobes printed as grid-based structures, with void hot spots within the lobes. The phantoms were filled with solutions of 177Lu (kidneys) or 99mTc (thyroids) and imaged with SPECT. For verification, Monte Carlo simulations of SPECT imaging were performed for activity distributions corresponding to those of the printed phantoms. Measured and simulated SPECT images were compared qualitatively and quantitatively. Micro-CT images showed that printing inaccuracies were mainly uniform across the grid. The relationships between the FVF from weighing and [Formula: see text] were found to be linear (r = 0.9995 and r = 0.9993 for 177Lu and 99mTc, respectively). The FVF-deviations from the design were up to 15% for thyroids and 4% for kidneys, mainly related to possibilities of cleaning after printing. Measured and simulated SPECT images of kidneys and thyroids exhibited similar activity distributions and quantitative comparisons agreed well, thus verifying the grid-based method. We find the grid-based technique useful for the provision of 3D printed, realistically shaped, phantoms with non-uniform activity distributions, which can be used for evaluation of different quantitative methods in SPECT imaging.

The effect of outer container geometry on the thermal management of lithium-ion batteries with a combination of phase change material and metal foam

The use of PCM for thermal management of the batteries has an important place among passive cooling methods because it does not require pump or fan power. In battery cooling applications with PCM, it was aimed to increase the thermal conductivity of the PCM and to cool the battery better by using fins, nanoparticles, and metal foam. The novelty of this study is to investigate the effect of outer container geometry on battery temperature in battery cooling with PCM + metal foam composition. In this direction, five different container geometries affecting the heat transfer by conduction and convection were analyzed. The parametric study was carried out for different values of convection heat transfer coefficient, heat generation in the battery, PCM amount, and porosity. The lowest battery temperature for a given discharge time was obtained in triangular container geometry. With the use of a triangular container, the battery temperature was reduced between 0.4 % and 14.42 % compared to the use of a circular container, depending on the parameter values. The analysis findings revealed that the outer container geometry is more effective in the thermal management of the battery for conditions with low convection heat transfer coefficient and high heat generation.

Evaluation of the behavior of the interface zone between an asphalt mixture and an inductive power transfer pad

Wireless charging of Electric Vehicles (EVs) is seen as part of an important strategy to reduce emissions from essential transportation trips of people and goods. Resonant Inductive Power Transfer (IPT) is used in the development of wireless charging systems for in-road charging systems. IPT pads are embedded in a pavement infrastructure to create a magnetic field that is coupled into a similar pad fitted underneath an EV. This is then converted to the voltage and current needed to charge the onboard battery. This method enables EVs to wirelessly receive a charge while stationary or in motion. However, ensuring the robustness of this integrated in-road system is essential. Poor interface bonding between a surrounding asphalt mixture and an IPT pad decreases the structural integrity within the IPT pad-asphalt pavement system, hence increasing the risk of damage to the system. The purpose of this study is to investigate the behavior of an IPT pad-asphalt interface zone by performing direct shear tests. In the experimental setup, a normal compressive load is applied to a three-layer cylindrical specimen, comprising an asphalt mixture, the interface material, and the material forming the outer containment layer of the pad. The influence of temperature, moisture, and normal stress on the interface shear strength is investigated. Among the three interface materials tested (epoxy bitumen, epoxy resin, and structural plastic adhesive), the epoxy resin material showed the highest shear strength at 25 °C. The interface shear strength and the shear stiffness decreased for all three materials with increasing temperature, with the epoxy bitumen material being the most temperature sensitive, yielding a decrease in strength of 77 % and stiffness of 62 % between 15 °C and 40 °C. Experiments were performed using an orthogonal test design. Five variables, known to affect the interface shear strength, each variable assuming three values, were considered. The results of a range analysis and analysis of variance (ANOVA) showed that temperature has the most significant effect on the shear strength of the interface zone, i.e. between the asphalt mixture and pad surfacing. Other important factors affecting the shear strength are the interface material and the shear deformation rate. A numerical study of a full-scale IPT-asphalt pavement system is presented to show the effect of the interface bonding condition on the longitudinal and transverse strains at the bottom of the asphalt layer and the fatigue life. The results of this study will be used in the design of an IPT pad-asphalt pavement system by minimizing the differential permanent displacements between an IPT pad and the surrounding asphalt pavement.

Microwave-assisted rapid synthesize of cadmium–thallium mixed fluoride hydrate complex and its physiochemical properties

Herein we report a facile and rapid, cost-effective microwave-assisted synthesis of mixed cadmium-thallium fluoride hydrate compound using a homemade vessel with a special protective outer container. The physicochemical properties of the prepared compound were investigated by several characterization techniques. Single crystal X-ray diffraction measurement was performed to investigate the crystal structure of the prepared compound. The XEOL intensity shows a good linear response as a function of the delivered X-ray dose, which indicates that this material can be highly desirable for radiation detection applications. The fitting of scintillation decay kinetic from a241Am α− radiation source, shows the fastest decay time constant of 40 ns (16%) with medium and slow components of 380 ns (72%) and 1.5 μs (12%) at room temperature. The pulse height spectrum shows the photopeak of α− particles produced by the 241Am radiation source at 5.48 MeV.

CALCULATION OF THE HEAT TRANSFER COEFFICIENT IN THE OUTER BODY FOR A ROTATIONAL DETONATION ENGINE

Unsteady heat transfer characterization on the combustion surfaces of rotational detonation engines (RDE) is not well understood. It is generally thought that the complex nature of the unsteady, reacting, compressible fluid flow inside the combustion annulus of the RDE causes the convective heat transfer coefficient to be significantly higher than it is in other applications. Empirical models that have been used to analyze this strictly apply to steady flows where dimensionless groups can be employed. Because of the complex flows in RDEs, it is not likely that they will lend themselves to explanation using simple dimensionless parameters. In this work a numerical study is performed where the inside wall surface temperature distribution in the RDE outer body is systematically changed over a given range that would be characteristic of the startup flows inside an RDE. For each case, temperature distributions inside the outer containment wall of the RDE were calculated and compared with experimental data. The closest match was then used to directly calculate the convective heat transfer coefficient on the inside surface of the RDE. The calculation results show that the local heat transfer coefficient C<sub>H</sub> is lower than what has been commonly used for these flows. The results show that C<sub>H</sub> is within the range of normal forced convection of a gas.

Pressure monitoring of Special Nuclear Material containment

All Magnox Nuclear Reactors are now in the process of decommissioning and nearly all Magnox spent fuel has been reprocessed, producing uranium and plutonium and small volumes of highly radioactive waste. The recovered plutonium is stored in specialist containers in secure facilities while the government reaches a decision on possible re-use or disposal, following the completion of technical studies. There is potential for the containment to become pressurised over time due to alpha decay and radiolysis of the plutonium, and highlights the need for continuous monitoring to assess the integrity of the containment. This paper presents a new technique of interpreting the internal pressure of the containment by understanding the change in the vibrational response of the outer containment wall for different internal pressures. Electromagnetic acoustic transducers have been used to excite the outer containment wall in a non-contact and non-destructive manner, and capture the changes in the resonant frequency response of the system for different internal pressures.

Optimization and application of passive air sampling method for gaseous elemental mercury in Ulsan, South Korea.

We compared uptake rates and concentrations of gaseous elemental mercury (GEM) by passive sampling conditions and investigated the spatial distribution of GEM in Ulsan, the largest industrial city in South Korea. For the optimization of sampling conditions, two outer sampling containers (cylindrical polyethylene terephthalate and two stainless steel bowls), two different sulfur contents of the sorbent (16.3% and 26.3%), and three sampling periods (1, 2, and 3months) were considered. The uptake rates of GEM were not statistically different by the sampling container, but they were increased with the sulfur contents of activated carbon. A sampling condition using two stainless bowls and lower sulfur contents of activated carbon for 2-3months was preferred with the highest precision of GEM concentrations. With the same method, passive air samples were collected for 3months in duplicate from 10 sites in Ulsan. The concentrations of GEM ranged from 3.13 to 11.2ng/m3 (mean 4.65ng/m3), and the highest concentration was measured at a non-ferrous industrial complex. A zinc smelter in the non-ferrous industrial complex was identified as a major mercury source in Ulsan. This study is the first passive air sampling study investigating the spatial distributions of GEM in different types of industrial areas as well as residential areas of Ulsan.

Dynamic model and earthquake response of a hybrid isolated system with tuned inerter dampers for nuclear power plants

Considering the benefits of tuned inerter damper (TID), a hybrid control system (TIDISO system) for third-generation NPPs consisting of an un-isolated outer containment structure, an isolated inner containment structure and a connecting TID system was proposed. First, governing equations of motion for the 3-degree-of-freedom (3DOF) model were derived and the seismic response variances of TIDISO system under white noise excitation were obtained. Next, an optimization study on inertance, frequency and damping parameters was conducted, and then simplified expressions were provided as a function of the various structural parameters for the optimal TID parameters. Through simulation comparisons, the accuracy of the expressions was further verified. Finally, a case study was conducted to demonstrate the proposed rapid-determining formula for optimal TID parameters and to estimate the effectiveness of the proposed TIDISO system under seismic waves. The results illustrate the proposed system is effective to suppress acceleration and story draft responses, especially for isolation displacement. Under artificial wave 1, the displacement of isolation layer has declined from 475 mm to 327 mm, nearly 32.7%.

Theoretical study and experimental verification on a passive control system with isolators and dampers for NPPs

A hybrid passive control system named damped isolated structural system (DISO system) for nuclear power plant structures (NPPs) with double containments is proposed in this paper, in which the outer containment is non-isolated and the inner containment and equipment are isolated with connecting damper installed between two containments. Firstly, a connected single degree of freedom (CSDOF) model was proposed. Subsequently, the vibration characteristics and parametric correlation analysis of proposed systems based on CSDOF model were analyzed. The acceleration and dimensionless displacement variances were derived. The optimal value is related to structural parameters, such as the mass ratio η, ratio of natural vibration frequency γ and structural damping ratio ξiξo. Through data fitting and calibration, the closed-form expression of the optimal parameter κopt is provided. The accuracy of the expression is verified by numerical simulation. Finally, a shaking table experimental study on the scale model was conducted to verify the theoretical results. The optimal damping parameter in the experimental study was calculated by the fitting formula (κopt). The results show that with optimal parameter, the acceleration and displacement responses of DISO system are both lower than traditional isolated structures (ISO system). The shaking table test results are well consistent with that of theoretical investigation conclusions.

Suggested two layers container for shielding the low and intermediate activity gamma-ray sources

Due to the advantages of using gamma-ray radiation sources in various fields, the average equivalent dose received due to the exposure to these sources increases. The wrong handling or direct exposure to these sources give raises the equivalent dose for the receiver. Thus, a container made up of two layers (metal and glass layers) was suggested to decrease the recorded equivalent dose received from the gamma-ray radioactive sources to an acceptable limit. The Monte Carlo MCNP simulation code was utilized to predict the equivalent dose around the container's outer surface and at 100 cm from the center of the outer container's faces. For example, the simulation study illustrated that the equivalent dose rate received at 100 cm from an unprotected 137Cs source with an activity of 3.7E+8 Bq is 26.30 μSv/h. This equivalent dose rate from an unprotected source is reduced to 22.75 μSv/h using the inner layer of the stainless steel with a thickness of 0.5 cm. After that, the equivalent dose rate reduced from 22.75 to 7.60 μSv/h, raising the WO3. Simultaneously, the equivalent dose rate from an unprotected Co-60 source reaches 50.51 μSv/h. It is reduced to 23.56 μSv/h by using a container consisting of an inner layer of stainless steel with a thickness of 0.5 cm and an outer glass layer of BaWP7 glass sample with WO3 content of 60 mol % and thickness of 5 cm.The present study showed the suggested container's ability in reducing the absorbed dose and equivalent dose rate for intermediate activity gamma-ray sources used in laboratories and nuclear medicine.

Математичні моделі та алгоритми оптимальної упаковки куль та кубів у сферичний та кубічний контейнери

Розглянуто математичні моделі та алгоритми оптимальної збалансованоїрозрідженої упаковки куль та кубів у сферичний та кубічний контейнери.Збалансованою розрідженою (задаються допустимі відстані між обʼєктами)упаковкою об’єктів у зовнішній контейнер є така їх упаковка, коли центрваги сімейства об’єктів збігається з центром зовнішнього контейнера, авідстані між об’єктами та відстані від них до зовнішнього контейнера булине менші за наперед задані величини. Наведено математичні моделі, послідовні та паралельні алгоритми розв’язання задач знаходження збалансованої розрідженої упаковки куль різних радіусів у сферичний та кубічнийконтейнери. Наведено математичну модель задачі знаходження збалансованої розрідженої упаковки кубів у куб мінімального обʼєму за умови, щосторони всіх кубів паралельні осям координат, та опис негладкої штрафноїфункції для пошуку локальних мінімумів задачі. Досліджувані задачівідносяться до класу NP-важких задач. Математичні моделі представленібагатоекстремальними задачами нелінійного програмування. Для пошукунайкращого допустимого розвʼязку застосовується метод мультистарту усполученні з r-алгоритмом Шора. Для цього задача зводиться до задачібезумовної оптимізації за допомогою штрафних функцій у вигляді функціймаксимуму, а для пошуку локальних мінімумів із набору стартових точокзастосовуються методи мінімізації негладких функцій, що базуються навикористанні програмних реалізацій r-алгоритму. Математичні моделі тапослідовні і паралельні алгоритми, що розглядаються, можна використатидля розробки програмних засобів розв’язування задач знаходження збалансованої розрідженої упаковки сферичних та кубічних обʼєктів у сферичніта кубічні контейнери. Матеріал представлено в трьох розділах. У розд. 1 наведено математичну модель та алгоритми розв’язання задачі знаходження збалансованої розрідженої упаковки куль різних радіусів у сферичнийконтейнер. Описано послідовний та паралельний алгоритми знаходженнянайкращого допустимого розв’язку задач. У розд. 2 наведено математичну модель та алгоритми розв’язання задачі знаходження збалансованої розрідженоїупаковки куль різних радіусів у кубічний контейнер. Описано послідовний тапаралельний алгоритми знаходження найкращого допустимого розв’язкузадач. У розд. 3 наведено математичну модель задачі знаходження збалансованої розрідженої упаковки кубів у кубічний контейнер. Наведено описнегладкої штрафної функції для пошуку локальних мінімумів задачі.

DECOMMISSIONING OF TELETHERAPY MACHINE AND TRANSPORT OF DECAYED TELETHERAPY SOURCE

Radioactive Cobalt-60 teletherapy machines find a prominent place in radiation therapy departments in India. The first teletherapy cobalt machine in SMS hospital (Picker Advance Tele Cobalt (ATC) C/9) was installed in 1995. The initial activity of the cobalt source was 333 TBq (9000 Ci).In March 2019, the source output became lesser than 50 cGy/hr at normal treatment distance (NTD) of 80cm which is clinically not acceptable for patient treatment because of increase in treatment time. The decommissioning of the machine was considered due to ageing of machine and vendor was not providing services anymore. This present study describes radiation safety aspect of the planning of decommissioning of teletherapy machine and transport of the decayed Cobalt-60 source for disposal and personnel dose measurements during the procedure. Decommissioning of the cobalt machine began with preparation of a plan and its submission for approval by competent national authority. Radiation survey of the source head was performed before the source transfer operation by AERB certified decommissioning engineers. Then decayed source was unloaded in shielded container (flask Sl No 112) and was kept in another outer container (type B (U) package). It transported for disposal to BRIT, Kota on receipt of transport permission fromAERB.A radiation survey was done in a matrix format of the all sides of this package.To measure the personnel doses, pocket dosimeter, TLD badge and OSLDs were used. The maximum dose received by the engineers was .03mSv. Maximum radiation level at 1 m from the external surface of the package was found 0.83mR/hr. The development of the new concepts and practices in the field of the decommissioning includes the preparation and approval of a decommissioning plan, the actual decommissioning operations as well the safe management of the waste arising from the decommissioning process. Such plans need to be developed for each facility with radiation sources.

Complex fluid flow in annular space under the effects of mixed convection and rotating wall of the outer enclosure

AbstractThis study aims to investigate the roles of pertinent parameters on the mixed convection of complex liquids in annular devices. The investigated area consists of two circular cylinders with fixed and heat walls. Both cylinders are enclosed within a circular room with a cold wall and rotate regularly. The zone between the inner obstacles and the outer space contains complex power‐law fluids. This investigation is numerically achieved by using the package ANSYS‐CFX, which is based on the finite‐volume method. The parameters studied in this study are the arrangement and size of inner tubes (d/D), the rotational speed of outer space, the rheological nature of fluids (n), and the relative concentration of thermal buoyancy force. These pertinent parameters were quantitatively expressed for the following values:d/D(= 0.1, 0.25, and 0.45); Reynolds number (Re = 1 to 20); flow behavior index (n = 0.6, 1 and 1.6); Richardson number (Ri = 0 to 100), respectively. It was found that increasing the thermal buoyancy value and the rotational speed of the outer container increases the rate of heat transfer of the cylinders in the vertical and horizontal arrangement. For example, for shear‐thinning fluid (n = 0.6), raising the value ofRifrom 0 to 100 increasesNuby 59.67% ford/D = 0.1. Also, the arrangement of the two cylinders differently affects the dynamic behavior of the fluid within the studied space.

Research on Light-Weighting Mechanism of Pressure Strengthening for Austenitic Stainless Steels Cryogenic Vessels

Abstract Pressure strengthening (PS) technology, also called cold stretching, is widely used to increase the allowable stress and reduce the weight of cryogenic pressure vessels (CPVs) made of austenitic stainless steels (ASSs). However, with taking accounts of the manufacturing process and service environment of CPVs, the main source of the strengthening effect for yielding strength improvement is still unclarified. Therefore, in this work, the effect of the 9% prestrain and low-temperature (−196 °C) on cryogenic mechanical properties of S30408 stainless steel was comparatively investigated by cryogenic tensile test and martensitic transformation measurement. After evaluating the main source of strengthening increments, the effect of prestraining on welded joints was studied by Vickers microhardness test. Then the engineering significance of performing the PS on a cryogenic inner vessel was explored based on finite element analysis (FEA). It revealed that at −196 °C, the strengthening effect of low-temperature plays a leading role for strength increments, though the yield strength can be increased obviously by prestraining at room temperatures. Meanwhile, the performing of 9% prestrain could enhance the distribution uniformity of the Vickers microhardness of welded joints. Furthermore, the prior operation of PS on inner vessels is beneficial to prevent further plastic deformation during the subsequent hydraulic test, avoid thermal insulation degradation of the vacuum jackets and even stress concentrations in roots of pipes, which is also of engineering significance to smooth the subsequent processes such as the assembly with outer containers and other product tests.