Pressure Tube Research Articles

Nuclear engineering and design nuclear heat supply system for a small district heating reactor

Small Modular Reactors (SMRs) are currently considered to be a potential solution for decarbonizing the district heating sector. The LUT Heat Experimental Reactor (LUTHER) is a concept for a small modular nuclear heating plant that is being designed to meet the demands of Nordic district heating networks while also incorporating high safety standards. This paper presents an extension of the work pursued by LUT University by proposing a reactor module that allows for easy scaling of unit sizes ranging from 2 MW to 120 MW. The pressure tube assembly geometry, which has been developed specifically for the LUTHER reactor module, was analyzed by modeling two significantly different-sized variants that utilize this unique structure. The modular design of LUTHER enables complete factory-assembly and the use of standard road transport for unit sizes up to 120 MW. This design prioritizes high inherent safety, targeting for siting near population centers. The proposed heating reactor concept offers a viable means of decarbonizing the district heating sector by replacing existing combustion-based production with emissions-free nuclear heat.

A Model for the Temperature Distribution in a Rolled Joint in a CANDU Reactor Exploiting the Decomposition of the β-Zr Phase

A competing-rates model is presented to account for operational changes in the metastable β-Zr phase of the Zr-2.5Nb alloy used to make CANDU reactor pressure tubes and is used to predict temperature gradients at the outlet rolled joints using the decomposition of the β-Zr phase as a proxy for temperature. High temperatures decompose the β phase by enhancing the formation of small particles of ω and α phases. Fast neutron flux causes the ω and α phases to shrink. This process is assumed to depend on the total volume of the particles, because they are comparable to, or smaller than, the size of the neutron displacement cascades. The barrier energy for thermal growth was determined to be 2.43 eV, when an Arrhenius A factor of 1013/s was assumed. The cross section for (ω+α)-phase shrinkage is 24.5 barns for Zr-2.5Nb irradiated in CANDU reactors. Assuming that the shrinkage is dominated by the migration of self-interstitial point defects, a defect production efficiency of 1.4% was found.

Data-model Interactive Health Condition Assessment for Hydropower Unit

Abstract The health condition assessment (HCA) of hydropower unit plays an important role in enhancing safe operation of hydropower stations and reducing maintenance costs. Due to the harsh environment, there are some problems of sensor data during the unit operations, including abnormal data, missing data and high-noise data. Also, it is difficult to obtain complete monitoring data during run-to-failure maintenance. These issues definitely cause the low-confidence HCA. Thus, a data-model-interactive HCA for hydropower unit was proposed. First, a high-fidelity 3D mechanism simulation model, interacting with the actual unit, was built using unit drawing data provided by manufacturers. Average values of the volute inlet pressure and draft tube outlet pressure were fed into the dynamics simulation model to obtain the simulated pressure pulsation data under working conditions (water head H and power P). Then, a long short-term memory based healthy condition model was constructed using the power parameters, simulation and normal pressure pulsation. After model construction, difference values between simulated pressure pulsation dataset and degradation state pressure pulsation dataset were calculated to build the performance degradation index (PDI), describing the HCA of units. Finally, the PDI was fed into the convolutional neural networks and long short-term memory model to achieve degradation trend prediction. Validation experiment was conducted to verify the effectiveness of proposed method using actual monitoring data and operating parameters of 6# unit in the hydropower station.

Hydride orientation near pressure tube-end fitting rolled joints

The connection between Zr–2.5%Nb pressure tubes and modified martensitic stainless steel-403 end fittings in Pressurized Heavy Water Reactors (PHWRs) at the rolled joint is a critical site marked by enhanced hydrogen diffusion and elevated tensile residual stresses. The application of circumferential stress above a threshold leads to the formation of radial hydrides. Formation of radial hydride leads to a drastic reduction in fracture toughness and increase in Delayed Hydride Cracking (DHC) velocity. A comprehensive understanding of residual stress, hydride orientation and radial hydride fraction in this region is essential for the assessment of pressure tube structural integrity. In this study, we employ 3D nonlinear finite element analysis to estimate the residual stresses near rolled joints for both 220 MWe and 700 MWe pressure tubes. Additionally, we pioneer an experimental investigation into hydride orientation near roll joints through internal pressurization of hydrided pressure tube and end fitting assemblies. The study delves into the influence of residual stresses due to rolling process on hydride orientation and radial hydride fraction, providing crucial insights for the evaluation of the structural integrity of pressure tubes.

Structural Design of Pressurized Tube Based on the Discrete Element Method–Computational Fluid Dynamics Coupled Simulation

In order to elucidate the impact of pressurized tubes’ structures on the sowing performance of pneumatic seed delivery systems, the EDEM–CFD coupled simulation method was employed to analyze the influence of pressurized tube parameters, including length (L), corrugation depth (S), corrugation width (K), and the number of corrugations, on seed movement characteristics, distribution uniformity, and airflow patterns. Simulation-validated experiments were conducted to study the impact of the optimal pressurized tube structure on seeding performance. The results indicate that pressurized tubes significantly enhance the uniformity coefficient of seed distribution, reduce seed velocity, and decrease the coefficient of variation in distribution uniformity. When pressurized tube parameters, specifically length (L), corrugation depth (S), corrugation width (K), and the number of corrugations, are set at 800 mm, 8 mm, 50 mm, and 6, respectively, the uniformity coefficient of seed distribution exceeds 95%, and the coefficient of variation in seed discharge consistency for each row is less than 3.2%. Moreover, the seed velocity at the outlet of the pressurized tube, the relative velocity of two-phase flow, and pressure loss are all minimal, indicating superior seeding performance. This research provides valuable insights into the analysis of seed movement characteristics within pressurized tubes and the optimization of their structural parameters.

Microstructure and fracture toughness of 850°C quenched and aged Zr-2.5Nb alloy

The Zr-2.5Nb alloy pressure tubes manufactured by Water Quenched and Aged (WQA) fabrication route has reportedly exhibited superior resistance against in-reactor dimensional changes. WQA route comprises three consecutive thermo-mechanical treatments viz., solution heat treatment (SHT), cold working and vacuum aging, which govern the final microstructure and therefore fracture toughness of the pressure tube material. This work describes the influence of SHT soaking duration, degree of cold working and aging temperature on the microstructure and fracture toughness of WQA Zr-2.5Nb alloy. WQA pressure tubes are expected to have better resistance to in-reactor dimensional changes. However, if proper care of hydrogen absorption during thermo-mechanical processing is not taken, though resistance to creep will improve expectedly but fracture toughness at ambient temperature will deteriorate.

The Construction and Application of an Internet-based Hospital-community-family Home Management Model

Objective: Based on the software, this study aims to develop a hospital-community-home management model and evaluate the impact of nursing interventions provided by home visiting nurses, aligning with national healthcare policies in China. Methods: In the Dongying area, hospitals collaborate closely with local communities and families to facilitate the smooth implementation of Internet + Nursing Services. Patients schedule appointments for a range of medical care services through mobile phone software, with staff accessing orders through the platform to provide professional treatment and nursing care to patients. Results: Currently, there are 214 registrants from 50 departments on the platform. From September 2021 to June 2023, a total of 3529 cases were handled the platform. The top 10 order items included heel blood collection (944 cases), graphic consultation (526 cases), neonatal jaundice measurement (463 cases), neonatal hearing screening (418 cases), gastrostomy tube care (368 cases), catheterization care (192 cases), venous blood sampling (155 cases), postpartum mammary gland unblocking (103 cases), surgical wound care (92 cases), PICC catheterization care (57 cases), and pressure tube placement care (57 cases). Conclusion: The hospital has successfully established a hospital-community-family home nursing model with specialist nurses playing a central role. Through the implementation ofInternet + Nursing Service, medical staff are able to provide quality medical and nursing care to patients who are unable to leave their homes, significantly improving patient convenience and conserving medical resources.

The use of methanol as a C1 building block.

Methanol is a key building block in the chemical industry. In recent years, it has been used as a C1 source in various organic transformations in the presence of a transition-metal catalyst. This protocol describes the ruthenium- and cobalt-catalyzed utilization of methanol in different types of methylation reactions and heterocycle synthesis. Initially, we describe the synthesis of tridentate ligands (L1-L3) and their corresponding Ru(II) complexes (Ru-1, -2 and -3) and then detail how to apply these Ru(II) complexes and Co/PP3 (PP3 = P(CH2CH2PPh2)3) in various methanol dehydrogenative coupling reactions. We discuss six types of transformations by using methanol or a methanol/water mixture. The experimental setup for all the catalytic reactions is similar and involves adding all the respective reagents and solvents to an argon-filled pressure tube, which is sealed (by screw cap) and refluxed at the indicated temperature before the desired products are isolated and characterized. The catalytic systems described in this protocol work well for both small-scale and preparative-scale synthesis of various N-methylated amines/amides, C-methylated products and quinazolinones. These catalytic reactions are greener and more sustainable than conventional synthesis methods, with only H2 and/or H2O as by-products, and we evaluate the 'green chemistry metrics' for a typical substrate. The total time required for the catalytic experiments described in this protocol is 16-28 h, and the operation time is 4 h. An average level of expertise in organic synthesis is required to carry out these protocols.

Tribological and corrosion behavior of hydrided zirconium alloy

Zirconium alloys (Zr-alloys) are used for the core components of nuclear reactors due to their exceptional properties, which make them suitable for the given applications such as low neutron absorption cross-section, good corrosion resistance, good wear resistance, good mechanical stability at high temperatures etc. The coolant water that flows inside the pressure tube contains LiOH to control the pH value of the coolant water, which can cause corrosion. The flow of coolant water produces low amplitude vibration, which can cause fretting wear of the components. Further, the coolant water at high temperature causes the hydride formation in the material, degrading the properties of zirconium alloys. The safe working of nuclear reactors is the prime objective, and the corrosion and wear behavior of the core components must be explored to prevent possible failure. Fretting wear or tribo-corrosion experiments were conducted on Zr‐2.5Nb alloy against SS-410 for varied fretting duration to understand the tribological response. Electrochemical corrosion experiments were performed under the aqueous solution of LiOH (10.4 pH) using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization technique. The comparison was made between the tribological and corrosion response of unhydrided‐Zr‐2.5Nb alloy (Zr‐2.5Nb) and hydrided- Zr‐2.5Nb alloy (Zr‐2.5Nb‐H). The hydride formation causes the reduction in corrosion resistance of Zr‐2.5Nb alloy. The oxide layer is formed during the wear and corrosion process which protects the material from further wear and corrosion respectively.

Negative Pressure Wound Therapy: Challenges, Novel Techniques, and Future Perspectives.

Significance: Negative pressure wound therapy (NPWT) has been in practice for decades, proving its utility in many applications, ranging from acutely infected wounds to complex combat wounds and skin grafting. It has been routinely demonstrated that NPWT has superior wound healing outcomes compared with previous standard-of-care therapies. However, the technique involves some challenges related to each of the components that comprise the therapy. The purpose of this article is to highlight the challenges, introduce the recent advancements, and discuss about the future directions in NPWT systems. Recent Advances: New techniques and materials have been developed to improve the currently used NPWT systems with promising results when utilized with appropriate indications. Many advancements have been introduced in modes of negative pressure delivery, pumps, interface dressings, adhesive dressings, and tubing technology. Critical Issues: An optimal NPWT system would avoid the common problems such as failure to deliver negative pressure due to loss of an airtight seal or tissue ingrowth into the interface dressing causing painful dressing changes and bleeding. Other challenges include infection control and patient pain and discomfort that may contribute to noncompliance. Future Directions: Many studies have been performed to evaluate the optimal combination of settings and components in various wounds; however, there is still no clear "best" answer for many specific patient-wound scenarios. Novel and emerging tissue engineering and regenerative medicine approaches could potentially be utilized in the future NPWT systems and thus, this review will discuss some novel ideas for future considerations.

Evolution of texture and intergranular stresses of αZr and minority phases in Zr-2.5Nb pressure tube through synchrotron X-ray diffraction

This study investigates the impact of different processing steps on the crystallographic texture evolution of αZr and minority phases βZr and ωZr, and intergranular stresses as a function of grain orientation in a Zr2.5Nb pressure tube. This was done by analysis of diffraction data recorded in the 1-ID line of the Advanced Photon Source for high energy X-Rays (∼80 Kev) in transmission geometry on three samples with different processing conditions: extruded, cold rolled and after autoclaving. The crystallographic texture of both αZr and βZr phases changes slightly after cold rolling, with the Burgers orientation relationship between the two phases remaining intact. The texture of βZr and ωZr shows that βZr decomposition during thermal treatment is sensitive to grain orientation. A new method was proposed to obtain the orientation dependence of the intergranular stresses from the experimental pole figures. Intergranular stresses in αZr grains were low after extrusion, but rolling significantly increased them, with values with magnitude as higher as 350 MPa and a strong dependence on grain orientation. The autoclaving treatment leads to important stress relaxation, but the dependence on grain orientation remains. The βZr phase grains exhibit significant intergranular strains in both extruded and cold-rolled conditions; the hydrostatic part was associated to the presence of Nb in solid solution, with content of ∼20 % and an orientation dependence of approximately ±1 at%. The deviatoric strain was attributed to intergranular stresses, with stresses below 80 MPa for the extruded sample and ranging from −600 to 400 MPa after cold rolling.

Study of grain growth kinetics of Zr-2.5%Nb alloy quenched from (α+β) and β-phase region

The Zr-2.5 %Nb is used as the Pressure Tube (PT) material in Pressurized Heavy Water Reactors (PHWRs) in both cold worked and stress relieved as well as heat treated condition. For the development of heat-treated pressure tube, process parameters need to be tuned to achieve optimum microstructure and texture. In microstructural aspect, prior β grain size is a very important factor in influencing the property of the material. Hence, the prior β grain growth kinetics of the Zr-2.5 %Nb alloy has been investigated by subjecting the material to different heat treatments. Different heat treatment temperatures have been chosen from (α+β) and β phase region. The β transus temperature was measured through dilatometry. Specimens were soaked for different time and the grain size were measured using optical metallography. The evolution of grain size with soaking temperature and time were analyzed to study the grain growth kinetics.

Propulsion and Suspension Concept of the Technical University of Munich Hyperloop Full-Scale Demonstrator

The hyperloop concept envisions a low pressure tube and capsules, called pods, traveling at the speed of commercial aircraft as a sustainable, future-proof mass transportation system between cities. However, in contrast to the use case of such a system, the detailed technical concept is still under development. One challenging difference in comparison to other modes of transportation lies in the technical concept of the infrastructure, which is hard to change in the long term and therefore allows a few iterations only. This study’s key contribution is to showcase the conceptual design decisions of the 24 m full-scale Hyperloop Demonstrator at the Technical University of Munich (TUM) for the propulsion and suspension system, featuring the design decision tree (DDT) method as a framework to visualize and explain the technical design decisions and dependencies of complex hardware systems. The construction of the full-scale demonstrator not only proved the feasibility of the concept but also provided valuable concept-level experiences, which are shared within this work. Compared to existing maglev and hyperloop concepts, the presented concept features a separated air-cored long stator propulsion system and a homopolar electromagnetic suspension at the bottom with the track wrapping around the vehicle, revealing promising advantages like the structural simplification of the infrastructure and the independence of the guideway and tube.

Machine learning decision support model for discharge planning in stroke patients.

Efficient discharge for stroke patients is crucial but challenging. The study aimed to develop early predictive models to explore which patient characteristics and variables significantly influence the discharge planning of patients, based on the data available within 24 h of admission. Prospective observational study. A prospective cohort was conducted at a university hospital with 523 patients hospitalised for stroke. We built and trained six different machine learning (ML) models, followed by testing and tuning those models to find the best-suited predictor for discharge disposition, dichotomized into home and non-home. To evaluate the accuracy, reliability and interpretability of the best-performing models, we identified and analysed the features that had the greatest impact on the predictions. In total, 523 patients met the inclusion criteria, with a mean age of 61 years. Of the patients with stroke, 30.01% had non-home discharge. Our model predicting non-home discharge achieved an area under the receiver operating characteristic curve of 0.95 and a precision of 0.776. After threshold was moved, the model had a recall of 0.809. Top 10 variables by importance were National Institutes of Health Stroke Scale (NIHSS) score, family income, Barthel index (BI) score, FRAIL score, fall risk, pressure injury risk, feeding method, depression, age and dysphagia. The ML model identified higher NIHSS, BI, and FRAIL, family income, higher fall risk, pressure injury risk, older age, tube feeding, depression and dysphagia as the top 10 strongest risk predictors in identifying patients who required non-home discharge to higher levels of care. Modern ML techniques can support timely and appropriate clinical decision-making. This study illustrates the characteristics and risk factors of non-home discharge in patients with stroke, potentially contributing to the improvement of the discharge process. STROBE guidelines.

Oxidation behavior of Zr-2.5Nb alloy exposed to steam in the temperature range of 600–1200 °C

Zr-2.5Nb pressure tube material was subjected to isothermal steam exposures in the range 600–1200 °C for different durations to predict its oxidation behavior during hypothetical accident scenarios. The oxidation exponent obtained from power law fitting of the thermogravimetry (TG) curves deviated from parabolic regime. Nevertheless, oxidation kinetics was described by determining the parabolic rate constants (Kp) in two temperature ranges: Kp = 0.029 exp(-111075/RT) (kg/m2)2/sec for 600–900 °C whereas Kp = 77652.6 exp(-254824/RT) (kg/m2)2/sec for 900–1200 °C. In the tested durations, only the 1000 °C sample has shown breakaway transition, after approximately 105 min and has absorbed the highest amount of hydrogen amongst all samples. The trend in hydrogen pickup fraction (HPUF) was verified by two complementary hydrogen determination methods. Clear differences were identified in the α-Zr(O) layer formed on the samples below and above 900 °C. In the α + β range of 600–900 °C, α-Zr(O) consisted of tiny β precipitates. At and above 900 °C in the fully β range, columnar α-Zr(O) grains were observed.

13 C NMR as an analytical tool for the detection of carbonic acid and pKa determination.

NMR spectroscopy has become a standard technique in studies both on carbon capture and storage. 13 C NMR allows the detection of two peaks for carbonated aqueous samples: one for CO2(aq) and another one for the species H2 CO3 , HCO3 - , and CO3 2- -herein collectively named Hx CO3 x-2 . The chemical shift of this second peak depends on the molar fraction of the three species in equilibrium and has been used to assess the equilibrium between HCO3 - and CO3 2- . The detection of H2 CO3 at low pH solutions is hindered, because of the concurrent liberation of CO2 when the medium is acidified. Herein, a valved NMR tube facilitates the detection of the Hx CO3 x-2 peak across a wide pH range, even at pH1.8 where the dominant species is H2 CO3 . The method employed the formation of frozen layers of NaH13 CO3 and acid solutions within the tube, which are mixed as the tube reaches room temperature. At this point, the tube is already securely sealed, preventing any loss of CO2 to the atmosphere. A spectrophotometry approach allowed the measurement of the actual pH inside the pressurized NMR tube. The chemical shift for H2 CO3 was determined as 160.33 ± 0.03 ppm, which is in good agreement with value obtained by DFT calculations combined with Car-Parrinello molecular dynamics. The H2 CO3 pKa value determined by the present method was 3.41 ± 0.03, for 15% D2 O aqueous medium and 0.8mol/L ionic strength. The proposed method can be extended to studies about analogs such as alkyl carbonic and carbamic acids.

Moisture Determination in CO2 Gas Cylinders for Application in Annulus Gas Monitoring Systems of Pressurized Heavy Water Reactors (PHWRs)

Background:: Critical monitoring of moisture content in annulus gas is required due to its detrimental effect on the pressure tube, leading to surface corrosion and finally the rupture of the pressure tube. Methods and Results:: The present work describes a simple and reliable thermo-analytical method for the quantitative determination of moisture in CO2 gas cylinders, using anhydrous barium chloride as the novel adsorbent material and simultaneous. Thermogravimetry - Differential Thermal Analysis - Evolved Gas Analysis (Fourier Transformed InfraRed Spectroscopy) [TG-DTA-EGA(FTIR)] as determination techniques. Conclusion:: Conclusion: Differential Scanning Calorimetry (DSC) coupled with Microscopy has been used to see the surface morphological variations during the heat treatment. The results of these studies are being discussed here.

Research on fuel injection characteristics of common rail system based on high pressure pipeline integration and matching

AbstractThe modular prediction model of high pressure common rail system was established to study the influence of high‐pressure pipeline integration matching on the fuel injection characteristics of common rail system. The influence of common rail volume on pressure building and pressure fluctuation in common rail tubes was analyzed. The influence of common rail volume on the matching of fuel injection frequency (number of fuel injectors) and fuel supply frequency (number of plunger pumps) was studied by using the control variable method, and the basic optimal solution of the system was obtained. The influence of the common rail structure on the fuel flow characteristics of the system was also studied. The matching relationship between high pressure tubing and common rail system is studied by introducing dimensionless numbers such as length‐diameter ratio of pipeline. The results demonstrate that the increase of the storage space of the accumulator can effectively reduce the fluctuation in the system, so that the injection volume increases slowly and then decreases rapidly, with a slope of −5.70 × 10−3 mm3. The increase of the diameter of the common rail makes the fuel flow characteristics become good first and then bad, and the increase of the length of the common rail can soothe the pressure fluctuations. The increase of the diameter of the link tube (LT) makes the fuel injection volume of the injector increase first and then decrease. The optimal VR solution for the LT is 0.0249 and the optimal ratio of the length to diameter of a pipeline solution is 55.10. The structure of the distribution tube and its matching to the common rail have little effect on the fuel flow characteristics. When the diameter and length of the injection tube are too large, the influence on the injection pressure of the injector is negatively correlated.

Effect of Hydride Morphology on Fracture behavior of Zr-2.5%Nb Pressure Tube Material

Hydrogen generated due to corrosion reaction is partly absorbed by Zr-2.5%Nb pressure tube (PT) material during service in the Pressurized Heavy Water Reactors (PHWRs). Hydrogen present in excess of the solubility limit get precipitated and embrittles the host PT material. The degree of embrittlement of the host PT matrix is governed by the morphology of the hydride precipitates. An experimental setup was designed, fabricated and used to form hydrides of different morphologies using internal pressurization. The internal pressure during the treatment was sufficient to induce hoop stresses more than the threshold for stress for re-orientation of hydrides in the PT spool. The design of the setup ensured constant pressure inside the PT spool while cooling from hydrogen solutionizing temperature. Metallographic examination of the hydrogen charged PT spool after the reorientation treatment revealed formation of stress reoriented hydrides. Series of burst tests were carried out on the PT spools with varying hydride morphology. The burst pressure as well as the final crack extension were found to be function of hydride morphology. This paper summarizes multiple full scale burst tests performed on as received Zr-2.5%Nb PT spools as well as on PT spools with varying hydride content and morphology.

Fretting wear assessment in PHWR pressure tubes using transient dynamic FEA and Archard’s wear model

In Pressurized Heavy Water Reactors (PHWRs), the fuel bundles are placed in a pressure tube (PT). These bundles rest on inside of pressure tubes through the bearing pads. The pressure tubes are part of the primary pressure boundary of the reactor, and are crucial from functionality and safety point of view. Any phenomena/ factors that may cause structural degradation of PT and may affect its structural integrity, requires thorough investigation. The fretting of pressure tube at bearing pad locations is one such phenomenon, wherein the local material removal due to fretting may lead to stress concentration and associated structural degradations. Therefore, a detailed assessment of the PT fretting damage incurred during its intended life is required. Present paper covers the premise and methodology based on Archard’s wear model for evaluation of the volumetric wear rate of pressure tube. A case study has been done to evaluate the fretting wear in pressure tubes of a large Indian PHWR. 3D transient computational fluid dynamic analysis and finite element analysis with contact modelled between the fuel bundle bearing pads and pressure tube are carried out to evaluate the contact force and sliding distance time histories. Based on the analyses results, the work rate and average saturated fret depth are evaluated. The assessment revealed insignificant concern owing to the fretting of pressure tube for the considered cases.