Full-scale Mock-up Research Articles

Unexpected thermal aging effect on brittle fracture and elemental segregation in modern dissimilar metal weld

A full-scale dissimilar metal weld safe-end mock-up, precisely replicating a critical component of a modern nuclear power plant, was investigated. The brittle fracture behavior, carbide evolution and nanoscale elemental segregation in the heat-affected zone (HAZ) of low alloy steel (LAS) were analyzed under both post-weld heat-treated and thermally-aged conditions (400 °C for 15,000 h, equivalent to 90 years of operation) using analytical electron microscopy and atom probe tomography. The observed increase in grain boundary (GB) decohesion and intergranular cracking on the fracture surface and the decrease of fracture toughness are primarily attributed to P and Mn segregation to GBs and the coarsening of carbides upon long-term thermal aging. The direct observations of significant elemental segregation to GBs and the consequent reduction in fracture toughness in the HAZ are unexpected for modern low-phosphorus LASs, highlighting potential concerns for evaluating the structural integrity of modern nuclear power plants.

Measurement of gamma field inside the biological concrete shielding of VVER-1000 Mock-Up at the LR-0 reactor

The long-term operation of existing nuclear power reactors is a crucial concern due to the complexities and expenses associated with replacing key components, such as the reactor pressure vessel and reactor internals. Gamma radiation, a byproduct of nuclear reactions and radioactive decay, significantly influences the lifetime of these components. This radiation is responsible for various degradation pathways leading to void swelling in steel reactor components and cracking or other radiation damage in concrete structures.A study conducted at a full-scale mock-up of the VVER-1000 reactor at the LR-0 zero-power reactor employed HPGe and stilbene measurements to analyze gamma spectra behind the reactor pressure vessel and within concrete biological shielding. While simulations behind the reactor pressure vessel aligned with measurements, notably, amarked overestimation of stilbene spectrum calculations occurred deep in concrete, suggesting potential inaccuracies in radiation predictions for power plant structures.

Interior Fabrications: rethinking the interior through hands-on prototyping

Exploring the intersection between design education and hands-on experience in real-world construction scenarios, this study seeks to address the gap between design concepts and their practical execution. An experimental seminar titled Interior Fabrications was invented to integrate construction knowledge with a theoretical investigation. First exposed to a range of tools and techniques through participation in a real-world design-build exercise, the students were then asked to deploy their skills within their own design work. Students considered how new typologies of interior partitions could impact spatial dynamics, the relationship between identity and the interior, and create new programmatic consequences. Physical engagement with materials and space allowed for new experimentation and ways of thinking about design, creating a stronger awareness and understanding of the built environment. The study focuses on the value of learning and experimenting through full-scale mock-ups of materials.

Design and vibration test of first mirror mount assembly for ITER divertor VUV spectrometer

The divertor vacuum ultraviolet (VUV) spectrometer is a diagnostic system in the ITER tokamak, monitoring impurity content and behavior in the divertor region. The first mirror of the spectrometer, made of silicon carbide (SiC), is exposed to harsh environmental conditions, including high temperatures and significant inertial loads from electromagnetic disruption events. To ensure its reliable performance, we have designed and tested a robust mirror holder assembly. This paper introduces a novel design of the first mirror holder assembly for the ITER divertor VUV spectrometer and presents the results from comprehensive vibration tests conducted on a full-scale mock-up. The design features a double-holder structure with spring plate assemblies to accommodate thermal expansion and resist vibrational loads. The mock-up underwent a series of resonance search, sine dwell, and random vibration tests, replicating the expected loads during vertical displacement events in ITER. The mirror holder assembly and the dummy mirror successfully withstood the vibration tests without damage, validating the design for the ITER environment. The results demonstrate the robustness and reliability of the mirror holder assembly, ensuring the accurate and reliable operation of the divertor VUV spectrometer in ITER.

Non-invasive ultrasonic sensing of internal conditions on a partial full-scale spent nuclear fuel canister mock-up

The safe storage of spent nuclear fuel (SNF) in dry cask storage systems (DCSSs) is critical to the nuclear fuel cycle and the future of nuclear energy. A critical component of DCSSs is the SNF canister. The canister is a sealed stainless-steel structure, which is first vacuum dried and then backfilled with helium. The structural deterioration within a canister can be monitored through its internal gas properties. This monitoring serves as the driving force behind the non-invasive ultrasonic sensing approach in this paper. A major challenge in collecting gas-borne signals using ultrasonic sensing is the impedance mismatch between the stainless-steel canister and the helium gas inside. Only a small fraction of the ultrasonic signal makes its way from the transmitter to the receiver through the gas medium. In this paper, experimental studies on a partial full-scale canister mock-up were carried out to capture the gas-borne signals. Damping materials were applied on the outside, and blocking and unblocking tests were conducted to identify the gas-borne signal. The research results showed that the excitation frequency played an important role in maximizing the gas-borne signals. The gas-borne signal was successfully detected at around the theoretical time-of-flight (TOF) at 225 kHz. A high signal-to-noise ratio (SNR) was achieved in the measurements. Next, acoustic impedance matching (AIM) layers were added, and it was found that the gas signal energy was improved by 160.4% compared with that of no AIM layers. Subsequently, the relative humidity (RH) level and temperature of the gas were varied to simulate abnormal internal conditions of the canister. The non-invasive testing system demonstrated reliability and sensitivity in detecting gas temperature and RH variations. Theoretical calculations demonstrated the potential for detecting low-level xenon and air within an actual SNF canister filled with helium. Last, an active noise cancellation (ANC) method, previously developed by the authors, was verified on the canister mock-up for the first time. The results showed that the SNR of the gas signal was improved by 213.6% compared with that of no ANC.

Investigating perforated egg crates as dynamic shading systems for open-plan offices in tropical climates

This study explores the use of perforated egg crates as a dynamic shading system to improve daylight quality by achieving better uniformity in open-plan offices. Glazed curtain walls, although a popular choice in modern open-plan offices, can cause problems especially in tropical climates, such as glare and heat particularly near the windows. As egg crates (EC) generally perform better as shading devices than plain horizontal or vertical systems, this study simulated three different combinations of perforated, solid, overlapping and non-overlapping egg crate models for an existing open-plan office building in Indonesia. Daylight measurements of the existing horizontal shading device without any egg crate (NO-EC) were first recorded. Subsequent simulations of non-overlapping perforated (EC-NP) egg crate models with different blade widths and blade rotation angles in accordance with the sun elevation angles on specified working hours were performed. Similar simulations were then performed for two combinations: other combinations of overlapping solid (EC-OS) and overlapping perforated (EC-OP) egg crate models. Finally, a full-scale site mock-up of the EC-NP and NO-EC were tested under real-life climatic conditions. Results show that EC-NP provides better uniformity than the other two combinations, which is within the range of 0.59–0.99. This is due to the deeper penetration of daylight achieved by the overlapping placement of the horizontal blades in front of vertical blades, while keeping the building envelope shaded.

A Q-band frequency tunable Doppler backscattering (DBS) system for pedestal and scrape-off layer density fluctuation and flow measurements in the DIII-D tokamak.

We present the design and laboratory tests for a new Q-band frequency tunable Doppler backscattering (DBS) system suitable for probing poloidal wavenumber kñ = 6-8cm-1 density fluctuations and their flow velocities in the pedestal and scape-off layer (SOL) of the DIII-D tokamak. This system will provide new measurements in the increasingly important and under-diagnosed far pedestal and SOL plasma regions. These results are important for experimental transport studies and necessary for the validation of transport models, both of which are important to fusion energy research. The use of a single tunable frequency reduces the complexity and potential failure points as compared to a multichannel system. This new system utilizes a 33-50GHz tunable source and will be integrated into the current V-band DBS in DIII-D using a broadband Q- and V-band multiplexer. A full-scale mockup of the quasi-optical system was used to test and optimize the performance. These tests include beam profile measurements at different distances (and angles) from a paraboloidal focusing and steering mirror. The measurements cover the full frequency range 33-75GHz of the integrated/combined Q-V band DBS system and target a large radial coverage of the low-field side of the plasma from ρ = 1.1 to ρ = 0.5, where ρ is the normalized flux surface radial coordinate.

Wooden Spatial Structures Assembled with Disassembly Possible Simple Joints

The authors propose a new clamped joint system that can easily join wooden members together and a wooden spatial structure that utilizes this system. The proposed system can clamp wood members without the need for special joint machining. Two types of clamps have been developed: orthogonal clamps and rotational clamps. A frame system is developed using this joint system, which is a hemispherical dome with a diameter of 5.4 m and its membrane is tensioned using struts. A preliminary framework structural analysis and membrane stress analysis are conducted to confirm the safety of the frame. Full-scale mock-up was constructed to validate the frame model analysis and verify construction procedures. As a combinable structure, a small-scale spatial structure assembled using orthogonal clamps is also described. It is the cube-shaped structure 2.8 m wide consisting of wall and ceiling planes. Single clamp loading tests are conducted to understand the load-deformation relationship of the proposed clamped joint system and full-scale horizontal loading tests have been conducted.

Blanket test facility for mockup testing on water cooled ceramic breeder blanket system

Intensive research and development activities have been conducted for designing a water-cooled ceramic breeder (WCCB) blanket system. In this system 325 °C/15.5 MPa of pressurized water removes heat injected and accumulated in blanket containers made of a reduced activation ferritic/martensitic steel, F82H. The container has lithium ceramics and beryllium pebbles as tritium breeder and neutron multiplier, respectively. In order to demonstrate performance of the system, especially for high-temperature pressurized water coolant, experimental apparatus have been installed in Rokkasho Fusion Institute, National Institutes for Quantum Science and Technology, Japan. These apparatuses enable to conduct the following experiment on full-scale mockups: 1) high heat flux (HHF) test to demonstrate heat removal of surface heat flux by electron beam gun simulating plasma, 2) flow assisted corrosion, 3) coolant ingress into dummy pebble beds, and 4) beryllium-water reaction between the coolant and the pebbles. In this paper, overviews, specifications, early results of these apparatus are reported.

Plant pixel: An optimized bio-inspired living wall system

Current Modular Living Wall Systems (MLWS) have many benefits but are often also characterized by high costs, high-embodied carbon and short life span materials. To address these issues a bio-inspired MLWS prototype was developed: Plant Pixel. The prototype aimed at improved performance on criteria: low-embodied carbon, hydrological and structural performance, plant performance, simple assembly-disassembly and cost-effectiveness. The Plant Pixel was built in a full-scale mock-up comprising 500 modules and 500 plants. It was found that the selected recycled materials (recycled PVCU, recycled textile, and recycled aluminum), a high-water holding capacity (61.0 l/m2) substrate, low-maintenance plants, and a plug-in fixing system, reduced embodied carbon (66.7 kgCO2e/m2) and improved the hydrological and structural MLWS performance. Additionally, the Plant Pixel prototype had lower material costs (256.1 €/m2) compared to other MLWS products. The Plant Pixel prototype met all the design criteria and exhibited the potential to become a marketable product.

The influence of ventilation on airborne transmission between stacking toilets

Multiple COVID-19 outbreaks in high-rise residential buildings have been linked to the vertical spread of the virus along the building. This study aimed to provide empirical evidence and experimental results to evaluate the effects of toilet ventilation on the spread of bathroom aerosols in high-rise residential buildings. This study explored potential transmission pathways by conducting tracer gas experiments in a full-scale mock-up toilet facility and identified effective strategies to minimize tracer gas surge and overall exposure. A novel IoT-enabled tracer gas sensing network was used to evaluate tracer gas dispersion from a lower-floor toilet to an upper-floor toilet and the roof under 32 different ventilation conditions of windows, exhaust fans, and forward-facing wind. The findings confirmed the potential for vertical airborne transmission through toilet ventilation and suggested effective ventilation strategies for forward-facing wind and no-wind conditions. This study provided novel experimental results on vertical aerosol transmission, contributing to further analysis and validation in this field. Appropriate ventilation measures were also discussed to ensure clean, virus-free air intake, reducing the risk of airborne cross-infection via the vertical transmission pathway.

Development of Zeolite Removal Robot for Decommissioning

The transfer of stagnant water from the basement floor of the waste treatment building at the Fukushima Daiichi Nuclear Power Station is planned because of the possibility of water flowing out of the building if another tsunami occurs. However, the basement floor is installed with high-dose zeolite sandbags as adsorbents for radioactive materials, which renders their removal challenging. In this study, we conduct a field survey and field reproduction as well as develop a robot that can perform zeolite removal based on the results obtained. In addition, we perform verification tests in a full-scale mock-up test environment and extract issues for application to actual equipment.

Functional tests for water cooled ceramic breeder blanket system using full-scale mockups

Intensive research and development activities have been conducted for preliminary design of a water-cooled ceramic breeder (WCCB) blanket system. As a part of these activities, some full scale mockups have been fabricated to verify feasibility, including manufacturing and inspecting procedures. This paper introduces an overview of the recent achievements in the mock-up testing on the WCCB blanket system. A blanket sub-module mockup have been manufactured using a reduced activation ferritic/martensitic steel, F82H with conventional industrial resources. As for water cooling system component, a mock-up of pneumatic isolation valve for DN50 pipe. The valve demonstrated sound operation after vertical and horizontal vibration simulating seismic loads. Moreover, the valve has demonstrated close / open operation in less than three seconds in magnetic field ranging from 290 to 500 mT, and the operation time was not affected by the magnetic field in this range. As for tritium storage device, mockup of ZrCo metal hydrate bed were also manufactured to find show stoppers in application as equipment for tritium extraction system (TES) in the WCCB-blanket system.

A computation design method for architectural artifacts adapted from traditional Kagome bamboo basketry techniques

This study is a digital form-finding and manual fabrication experiment in woven architectural design, with one traditional weaving style, Kagome, used to scale the craft up into an architectural-scale bamboo woven artifact. Kagome is a trihexagonal pattern employed in traditional bamboo basketry as a triaxial weaving system, resulting in an object with a self-bracing capacity without the use of fasteners owing to its interlacing lattices. Although existing studies and tools have addressed triaxial weaving design and representation, the current consideration of the advantages of weaving with bamboo is insufficient. To address this research gap, this study develops a computational design method based on studies on bamboo basketry. This allows for the representation and exploration of design geometries using combinations of regular triangular meshes for the fabrication of Kagome woven bamboo artifacts. A full-scale mock-up was fabricated to evaluate the effectiveness of the method. The mock-up demonstrated the self-bracing properties of Kagome, but there were discrepancies between the mock-up and the design. Factors affecting bamboo weaving on an architectural scale have been identified within this study to inform future research on woven bamboo structures.

Static and dynamic airflow and contaminant transport in a full-scale elevator-lobby mockup

Elevators facilitate people's movement in daily life. The confined space with high population density in elevators, however, assists the transmission of infectious diseases. To study disease transmission under various transit and boarding-period scenarios, this study used a full-scale elevator mockup with a connected lobby area. This investigation measured both static and dynamic distributions of air velocity/temperature and contaminant concentration. The static experiment involved the closed elevator cabin with mixed ventilation, while the dynamic measurements were conducted in the elevator with the door open to the adjacent lobby area when a passenger exited the elevator. The dynamic experiment showed that high-frequency instruments and better background airflow design could increase the data quality. The experimental data was then used to validate a computational fluid dynamics (CFD) model. This study compared the average and individual experimental data to minimize the uncertainties caused by the initial conditions and instrument limitations. The simulation results revealed that an in-transit elevator cabin is characterized by relatively uniform distributions of air temperature and contaminant concentration. The airflow in the dynamic case was greatly affected by the wake generated by passenger movement. This wake effect was short in duration, but it drew contaminants farther along the direction of movement.

Issues Associated with Yellow Phase Formation and Other Disruptions in Japanese High-Level Waste Vitrification and Their Improvement

The Rokkasho Reprocessing Plant, located in northern Japan, includes facilities for reprocessing spent nuclear fuels and immobilizing high-level waste (HLW) into a stable-glass waste form based on borosilicate. The vitrification process consists of two large liquid-fed, joule-heated, ceramic-lined melters (LFCMs). During the active test campaigns at the Rokkasho Vitrification Facility, unstable melting performance and difficulty in glass operation were observed in the LFCM operation. The operating protocols that had been developed in the earlier full-scale mock-up testing with inactive waste simulants were found to be inadequate to manage a stable LFCM operation. We needed to understand correctly the fundamental causes for the operational difficulties experienced in the active test. First, we studied and summarized the troublesome element behaviors and disturbances in the HLW vitrification process, primarily on the LFCM. Second, we proposed an empirical model, including the transition of the phenomena that appeared in the active LFCM operation. Third, we analyzed the operating data and the trend of operation indexes to find out the fundamental causes for the unstable LFCM operation based on the results obtained in the described model. It was revealed that the presence of a significant amount of molybdenum and sulfur, together with the noble metals (NMs) Ru, Rh, and Pd in the Rokkasho HLW stream could lead to the formation of molybdate and sulfate salt phases [yellow phases (YPs)], and subsequently, the sedimentation of NMs at the bottom of the melter. The YPs may concentrate at the melter bottom and clog the pouring nozzle prior to the bottom accumulation of NM sludge, which can disrupt power deposition and cause difficulties during glass pouring operation. Based on these investigated results, we provide insights into short-term countermeasures, including numerical control of the heat balance in the melter, dilution of HLW feed with inactive waste simulants, and periodic rinsing of the bottom glass. We also provide an evaluation of their validities on the active operation through full-scale mock-up testing. However, the periodic rinsing and dilution operation produce additional glass-filled canisters and increase the total backend cost. Finally, we see a couple of important directions for future research and development. An advanced LFCM system has been developed for the long-term countermeasures to introduce recent advances in the LFCM design with YP and NM compatibilities. Furthermore, the modified or new glass formulations, which can incorporate more waste oxides into the glass matrix, known as high-waste loading glasses, also have been developed in parallel.

Experimental studies on the effect of ceiling materials on the sound environment of underpass concourse using the station simulator

Sound environments in railway stations are often noisy because of sound-reflective materials and many noise sources. Especially in underpass concourses, structure-borne sounds are radiated from the ceiling due to vibrations when trains pass by. This results in a high noise level, which often interferes with listening to the announcements. In this study, to examine interior materials that effectively reduce such noise in railway stations, the following measurements and laboratory experiments were carried out: 1) Field measurements of vibrations of the ceiling and environmental sound in stations in Tokyo. 2) Reproduction of vibrations and sounds in the station simulator (full-scale mock-up of a station building), under the four different types of ceilings. 3) Auditory tests to evaluate the noisiness of train passing sounds and environmental sounds, using reproduced sounds in the station simulator as test sounds. As a result, the ceiling with damping material was effective for structure-borne sound, while the ceiling with porous sound-absorbing material was effective for air-borne sound. This result suggests that it is important to consider the placement of ceiling materials according to the noise situations.

Full-scale installation trial of ITER's in-vessel and marshalling area loom prototypes

The in-vessel components of the ITER Diagnostics are located all over the inner shell of the Vacuum Vessel, in the Ports and on the Divertor Cassettes as well. The electrical transmission lines which transmit the signals from the sensors across the vacuum boundaries are Mineral Insulated Cables. These cables will be arranged into looms, which will be fixed to the vacuum vessel with different kinds of attachments.The ITER tokamak is at a stage where manufacturing and testing of each component are becoming more and more important. For this reason, to allow IO to assess feasibility, gain experience and obtain feedback with respect to the suitability of the current designs regarding handling and installation of in-vessel signal cables and loom components, GEMS Engineering has carried out a series of installation trials on full-scale mockups of in-vessel and divertor looms, upper and lower port marshalling area looms. Beside of installation trials, the scope of the work also covered the manufacturing and testing of cable clamps and clips for in-vessel and divertor looms and marshalling areas.This paper outlines the results of the manufacturing of prototypes and assembly trials of the above-mentioned components.

Mood regulates the physiological response to whole-body vibration at low intensity

In the present study we evaluated the relationship between human vibrational comfort and psychophysiological processes. We exposed twenty-one participants to three levels of whole-body vibration at low intensity inside a full-scale mock-up of a ship cabin. Autonomic Nervous System (ANS) activity, mood and well-being state during each level of vibration exposure were measured. We found that a positive affective state determined greater changes in ANS activity in response to vibration variations compared to a negative affective condition. Furthermore, we found that variations of the vibration intensity did not always determine variations of the comfort experience at physiological and psychological level. The relevance of our findings is a challenge for comfort design research showing a gap between guidelines for comfort design and evidence based on psychophysiological responses to environmental stimulation.

Modelling a Turbulent Non-Premixed Combustion in a Full-Scale Rotary Cement Kiln Using reactingFoam

No alternatives are currently available to operate industrial furnaces, except for hydrocarbon fuels. Plant managers, therefore, face at least two challenges. First, environmental legislation demands emission reduction. Second, changes in the origin of the fuel might cause unforeseen changes in the heat release. This paper develops the hypothesis for the detailed control of the combustion process using computational fluid dynamic models. A full-scale mock-up of a rotary cement kiln is selected as a case study. The kiln is fired by the non-premixed combustion of Dutch natural gas. The gas is injected at Mach 0.6 via a multi-nozzle burner located at the outlet of an axially mounted fuel pipe. The preheated combustion air is fed in (co-flow) through a rectangular inlet situated above the attachment of the fuel pipe. The multi-jet nozzle burner enhances the entrainment of the air in the fuel jet. A diffusion flame is formed by thin reaction zones where the fuel and oxidizer meet. The heat formed is transported through the freeboard, mainly via radiation in a participating medium. This turbulent combustion process is modeled using unsteady Favre-averaged compressible Navier–Stokes equations. The standard k-ϵ equations and standard wall functions close the turbulent flow description. The eddy dissipation concept model is used to describe the combustion process. Here, only the presence of methane in the composition of the fuel is accounted for. Furthermore, the single-step reaction mechanism is chosen. The heat released radiates throughout the freeboard space. This process is described using a P1-radiation model with a constant thermal absorption coefficient. The flow, combustion, and radiative heat transfer are solved numerically using the OpenFoam simulation software. The equations for flow, combustion, and radiant heat transfer are discretized on a mesh locally refined near the burner outlet and solved numerically using the OpenFoam simulation software. The main results are as follows. The meticulously crafted mesh combined with the outlet condition that avoids pressure reflections cause the solver to converge in a stable manner. Predictions for velocity, pressure, temperature, and species distribution are now closer to manufacturing conditions. Computed temperate and species values are key to deducing the flame length and shape. The radiative heat flux to the wall peaks at the tip of the flame. This should allow us to measure the flame length indirectly from exterior wall temperature values. The amount of thermal nitric oxide formed in the flame is quantified. The main implication of this study is that the numerical model developed in this paper reveals valuable information on the combustion process in the kiln that otherwise would not be available. This information can be used to increase fuel efficiency, reduce spurious peak temperatures, and reduce pollutant emissions. The impact of the unsteady nature of the flow on the chemical species concentration and temperature distribution is illustrated in an accompanying video.