Gas Material Research Articles

Ion Chemistry in Dielectric Barrier Discharge Ionization: Recent Advances in Direct Gas Phase Analyses.

Dielectric barrier discharge ionization (DBDI) sources, employing low-temperature plasma, have emerged as sensitive and efficient ionization tools with various atmospheric pressure ionization processes. In this review, we summarize a historical overview of the development of DBDI, highlighting key principles of gas-phase ion chemistry and the mechanisms underlying the ionization processes within the DBDI source. These processes start with the formation of reagent ions or metastable atoms from the discharge gas, which depends on the nature of the gas (helium, nitrogen, air) and on the presence of water vapor or other compounds or dopants. The processes of ionizing the analyte molecules are summarized, including Penning ionization, electron transfer, proton transfer and ligand switching from secondary hydrated hydronium ions. Presently, the DBDI-MS methods face a challenge in the accurate quantification of gaseous analytes, limiting its broader application in biological, environmental, and medical realms where relative quantification using standards is inherently complex for gaseous matrices. Finally, we propose future avenues of research to enhance the analytical capabilities of DBDI-MS.

Spectroscopic analysis of single and multiphase electrical discharge for clean energy conversion

Abstract In this study, we examined non-thermal atmospheric pressure plasma processes operating under varying conditions using different liquid and gaseous hydrocarbon materials. The light emission from the discharges were analyzed through optical emission spectroscopy to comprehend the products generated in different parameter space. The gaseous products from each of these analyses were also collected and analyzed through gas chromatography. Analysis of the optical emission from the discharge and concentration of the gaseous products show a linear trend between emission intensity ratio Hα/C2 and gas concentration ratio H2/C2Hx. Gas temperature and electronic excitation temperature of different experimental conditions were also compared and indicates that spark discharge relates to higher electronic excitation temperature compared to glow discharge of similar medium. Higher electronic excitation temperature leads to generation of different products from spark discharge compared to glow discharge. Glow discharge generates more of the intermediate products. Whereas spark discharge, because of its higher electronic excitation temperature, leads to higher rate of dissociation and therefore generates more of the dissociated products. Glow discharge, for example generates more of OH and H from the moisture present in the carrier gas as impurity, whereas spark discharge would generate more of Hα and O particles further breaking down the OH bonds. Finally, UV-Vis analysis was performed on the liquid products of the discharge and reveals that the photo-centers and the newly generated soot nano particles absorb the UV range lights and some of the visible range light emission mostly up to ~600nm.

Development and Implementation of an Algorithm for Predicting the Intensity of Sorption of Hazardous Gaseous Materials

An algorithm for predicting the intensity of sorption of gaseous materials released into the atmosphere as a result of an accident is proposed. The algorithm consists of three hierarchical levels: monitoring the parameters of gaseous material emission, predicting the consequences of gaseous material emission before and after sorption, and making a management decision. The first hierarchical level includes 4 blocks: obtaining information from the chemical reconnaissance group and the facility representative on the type, amount of hazardous gaseous materials, release intensity and scale of the accident; obtaining information from the hydrometeorological service on temperature, atmospheric pressure, wind direction and speed in the accident area; processing the information received; information on the availability of forces and means for sorption of hazardous gaseous materials. The second hierarchical level also includes 4 blocks: readiness of forces and means for sorption of hazardous gaseous materials; calculation with sorption; calculation without sorption; determination of the boundaries of the chemical damage zone according to the established criteria. At the third hierarchical level, there is 1 block: making a management decision. The software implementation of the proposed algorithm was carried out. The use of the developed algorithm and its software implementation will increase the speed and accuracy of predicting the consequences of the release of hazardous gaseous materials in an accident.

Cuboid obstacle influence on high-pressure jet dispersion: A CFD study

In the context of the process industry safety, one of the main accidental scenarios is the release of high-pressure gaseous material. Since natural gas is highly flammable, the likelihood of ignition increases as the jet develops, with a maximum area of effect related to its lower flammability limit (LFL). This work aims at simulating and evaluating the interaction between high-pressure natural gas jets and cuboid obstacles, which were selected due to their prevalence in the process industry as storage units or buildings present in industrial parks. The maximum extent of the cloud at the LFL of natural gas is often influenced by the jet-obstacle interactions, necessitating complex numerical methods like computational fluid dynamics (CFD) for accurate estimation. Therefore, this study provides pivotal insights that challenge traditional modelling approaches, like integral ones, offering cost-effective alternatives where needed without compromising on safety.The findings indicate that using a CFD approach is not always necessary, as it largely depends on the storage pressure, diameter size, and the release height of the jet. At storage pressures of 65–130 bar with an orifice diameter of 2.54 cm, and a release height above 2.75 m, simpler methods like integral models are applicable without any substantial reliability loss. This is especially true when the cuboid obstacle is farther away from the release source. At lower release heights, especially if coupled with a larger orifice diameter, the CFD approach should be utilised as jet-cuboid interactions become highly relevant to the development of the jet.

Analyzing multispectral emission and synchrotron data to evaluate the quality of laser welds on copper

The validation of laser welding of metallic materials is challenging due to its highly dynamic processes and limited accessibility to the weld. The measurement of process emissions and the processing laser beam are one way to record highly dynamic process phenomena. However, these recordings always take place via the surface of the weld. Phenomena on the inside are only implicitly recognizable in the data and require further processing. To increase the validity of the diagnostic process, the multispectral emission data are synchronized with synchrotron data consisting of in situ high-speed images based on phase contrast videography. The welding process is transilluminated by synchrotron radiation and recorded during execution, providing clear contrasts between solid, liquid, and gaseous material phases. Thus, dynamics of the vapor capillary and the formation of defects such as pores can be recorded with high spatial and temporal resolution of <5 μm and >5 kHz. In this paper, laser welding of copper Cu-ETP and CuSn6 is investigated at the Deutsches Elektronen-Synchrotron (DESY). The synchronization is achieved by leveraging a three-stage deep learning approach. A preprocessing Mask-R-CNN, dimensionality reduction PCA/Autoencoders, and a final LSTM/Transformer stage provide end-to-end defect detection capabilities. Integrated gradients allow for the extraction of correlations between defects and emission data. The novel approach of correlating image and sensor data increases the informative value of the sensor data. It aims to characterize welds based on the sensor data not only according to IO/NIO but also to provide a quantitative description of the defects in the weld.

Stimulus-Responsive Gas Marbles as an Amphibious Carrier for Gaseous Materials.

Gas marbles are a new family of particle-stabilized soft dispersed system with a soap bubble-like air-in-water-in-air structure. Herein, stimulus-responsive character is successfully introduced to a gas marble system for the first time using polymer particles carrying a poly(tertiary amine methacrylate) (pKa ≈7) steric stabilizer on their surfaces as a particulate stabilizer. The gas marbles exhibited long-term stability when transferred onto the planar surface of liquid water, provided that the solution pH of the subphase is basic and neutral. In contrast, the use of acidic solutions led to immediate disintegration of the gas marbles, resulting in release of the inner gas. The critical minimum solution pH required for long-term gas marble stability correlates closely with the known pKa value for the poly(tertiary amine methacrylate) stabilizer. It also demonstrates amphibious motions of the gas marbles.

Methodology for determining the design parameters of combined type plasma-chemical reactor for gasification of carbon-containing raw materials

The paper shows the advantages of combined type reactors for plasma-chemical allothermic processes of carbon-containing raw materials gasification. The methodology for determining the design parameters of combined type plasma-chemical reactor for gasification of carbon-containing raw materials is developed. Analytical dependences for determination of time and constructive parameters of the combined type plasma-chemical reactor are established. Dependences contain interrelation between the main technological parameters of the process of thermo-conversion of carbon-containing raw materials taking into account thermochemical reactions. Dependences of constructive parameters of reaction zone of combined type plasma-chemical reactor for steam plasma gasification of carbon-containing media are obtained. It is established that at steam gasification of carbon-containing raw materials with the maximum particle size of 150 microns and the temperature in the reaction zone of 5000 K the volume of the reaction zone depends on the productivity of carbon-containing raw materials, which has a significant effect on the design parameters of the reaction zone.

Design Change and Operational Consideration of the HVAC System during Nuclear Power Plant Decommissioning

The heating, ventilation, and air conditioning (HVAC) system plays a crucial role in ensuring the safety of workers and preventing the release of gaseous radioactive materials into the environment during the decommissioning of a nuclear power plant (NPP). To establish an HVAC operation strategy, decommissioning phases were divided into four stages, and the HVAC systems were reclassified. In addition, assumptions have been made regarding design modifications and maintenance for the reactor containment building (RCB) HVAC, fuel handling building (FHB) HVAC, and main control room (MCR) HVAC. Based on these, for RCB HVAC operation, natural ventilation and RCB purge operation during the transition period are proposed. In the decommissioning stage, recirculation operation, entire ventilation operation consisting of continuous operation and purge operation, and finally partial ventilation operation to purify local space were proposed. Moreover, during the transition period, the FHB HVAC was proposed to operate as normal NPP, and the MCR HVAC was suggested to operate with safety-related equipment removed.

Potential Strategy to Control the Organic Components of Condensable Particulate Matter: A Critical Review.

More and more attention has been paid to condensable particulate matter (CPM) since its emissions have surpassed that of filterable particulate matter (FPM) with the large-scale application of ultralow-emission reform. CPM is a gaseous material in the flue stack but instantly turns into particles after leaving the stack. It is composed of inorganic and organic components. Organic components are an important part of CPM, and they are an irritant, teratogenic, and carcinogenic, which triggers photochemical smog, urban haze, and acid deposition. CPM organic components can aggravate air pollution and climate change; therefore, consideration should be given to them. Based on existing methods for removing atmospheric organic pollutants and combined with the characteristics of CPM organic components, we provide a critical overview from the aspects of (i) fundamental cognition of CPM, (ii) common methods to control CPM organic components, and (iii) catalytic oxidation of CPM organic components. As one of the most encouraging methods, catalytic oxidation is discussed in detail, especially in combination with selective catalytic reduction (SCR) technology, to meet the growing demands for multipollutant control (MPC). We believe that this review is inspiring for a fuller understanding and deeper exploration of promising approaches to control CPM organic components.

The Carbon Isotopic Ratio and Planet Formation

We present the first detection of 13CCH in a protoplanetary disk (TW Hya). Using observations of C2H, we measure CCH/13CCH = 65 ± 20 gas with a CO isotopic ratio of 12CO/13CO = 21 ± 5. The TW Hya disk exhibits a gas phase C/O that exceeds unity, and C2H is the tracer of this excess carbon. We confirm that the TW Hya gaseous disk exhibits two separate carbon isotopic reservoirs, as noted previously. We explore two theoretical solutions for the development of this dichotomy. One model represents TW Hya today with a protoplanetary disk exposed to a cosmic-ray ionization rate that is below interstellar as consistent with current estimates. We find that this model does not have sufficient ionization in cold (T < 40 K) layers to activate carbon isotopic fractionation. The second model investigates a younger TW Hya protostellar disk exposed to an interstellar cosmic-ray ionization rate. We find that the younger model has sources of ionization deeper in a colder disk that generates two independent isotopic reservoirs. One reservoir is 12C-enriched carried by methane/hydrocarbon ices, and the other is 13C-enriched carried by gaseous CO. The former potentially provides a source of methane/hydrocarbon ices to power the chemistry that generates the anomalously strong C2H emission in this (and other) disk systems in later stages. The latter provides a source of gaseous 13C-rich material to generate isotopic enrichments in forming giant planets, as recently detected in the super-Jupiter TYC 8998-760-1 b by Zhang et al.

In Situ Synchrotron Investigations of Beam Diameter Influence on Vapor Capillary Formation during Laser Beam Welding of Copper Alloy with a Blue Laser Beam Source

Laser beam welding as a reliable tool for high-precision joining of batteries or microelectronics is more and more the choice for achieving reproducible results in production processes. In addition to a high automation capability, the precise control of the energy deposition into the material plays an important role, especially when highly reflective materials, such as copper or aluminum, must be welded together. Alongside the use of highly brilliant fiber lasers in the near-infrared range with a focal diameter of a few tens of micrometers, diode lasers in the wavelength range of 445 nm are increasingly being used. Here, beam diameters of a few hundred micrometers can be achieved. With a wavelength of 445 nm, the absorptivity in copper can be increased by more than a factor of 10 compared to a near-infrared laser beam sources in solid state at room temperature. This paper presents the in situ X-ray observation of laser welding processes on CuSn6 with a laser beam source with a wavelength of 445 nm using synchrotron radiation at DESY Petra III Beamline P07 EH4 in Hamburg, Germany. For the experiments, the laser radiation was focused via two separate optics to focal diameters of 362 µm and 609 µm. To characterize the dynamics of the vapor capillaries depending on the different focal diameters dF, the parameters were varied with respect to laser power PL and feed rate v. For the investigations, a synchrotron beam of 2 × 2 mm2 in size with a photon energy of 89 keV was used, and the material samples were analyzed by means of phase-contrast videography to show the boundaries between solid, liquid, and gaseous material phases. The results of this paper show the welding depths achieved and how the geometry of the vapor capillary behaves by changing the focal diameter, laser power and feed rate.

Hybrid Reactor by the Combination of Water Electolyzer with Methanation Reactor Targeting the Space and Terrestrial Applications

Japan Aerospace Exploration Agency (JAXA) collaborates with Toyama University and Kyushu University to create the hybrid system where the water electrolyzer is directly combined with Sabatier reactor shown in Fig. 1.In order to generate oxygen, people use water electrolyzer. Under the micro-gravity condition, the specially designed gas-water separator is always needed to generate oxygen for breezing. The hydrogen which is the by-product from water electrolysis can also be used for the reduction reaction of carbon dioxide to generate methane and water. It is so called ‘Sabatier reaction’ which is very convenient for the water recovery in the closed environment.In general, the Sabatier reaction can be triggered with maintaining rather high temperature above 300 degrees C. However, the conversion of the reaction should become higher at lower temperature since the reaction is exothermic.We first focused our efforts to develop the catalysts which realizes the Sabatier reaction at around 200 degrees C.We then tried to transfer the heat generated from the Sabatier reaction to the water electolyzer.The novel internal structure of the water electolyzer was developed. Pressurized water without circulation is supplied to the water electrolyzer in which the interdigitated electrode locates. Water first contacts to the proton conducting electrolyte directly, and then diffuses to the electrode where the electrolysis reaction takes place. The electrode is covered with the hydrophobic materials so that only the gaseous material should pass through it without using any gas-water separation devices. The heat transferred from the Sabatier reaction enhances the efficiency of the water electrolysis reaction. By the combination, oxygen can be used for breezing, and hydrogen can be used for the reduction reaction of carbon dioxide to create water and methane as a unitized device.We successfully demonstrated the performance of the tandem device where the water electolyzer is combined with Sabatier reactor through both experiment and mathematical modeling.AcknowledgmentsThis work was partially supported by JST CREST and NEDO Green Innovation Fund Projects. Figure 1

Platinum Catalysts via Fluidized Bed Atomic Layer Deposition for PEM Fuel Cells

One of the major challenges for viable and durable proton exchange membrane fuel cells (PEMFC) in heavy duty applications is the development of stable and high-performing catalysts. The highest mass activities and stabilities can be achieved with platinum nanoparticles supported on a porous carbon support. However, these systems still suffer from degradation processes during cell operation, such as carbon corrosion and Ostwald ripening. [1] Atomic layer deposition (ALD) is an attractive alternative to the conventional wet chemical deposition of the platinum catalyst onto the carbon, promising to counteract these problems. [2,3]ALD is a surface coating method, which employs self-limiting half-reactions between gaseous precursor molecules and a solid substrate surface. Usually, two half-reactions separated by purging or vacuuming steps represent one ALD cycle. By performing a defined number of cyclic repetitions, thin films or nanoparticles can be grown on the substrate surface with atomic-layer precision. [4]Typically, ALD is used to coat flat surfaces. To achieve homogeneous coatings on powders, so-called fluidized bed ALD reactors fluidize the nanoparticle-powders in a gas flow, which also contains the gaseous precursor materials. This method ensures a high utilization of the precursor molecules while providing a good mixing of the sample. Thin films and nanoparticles can be deposited in a homogeneous manner onto the powder surface and into its pores. [4]Carbon corrosion of PEMFCs can be suppressed by applying conformal ALD coatings onto the support structure. Additionally, a porous overcoating can fixate the nanoparticles against detachment and dissolution while still leaving access to the reactive sites. [5] Applying ALD to deposit fuel cell catalysts with monodisperse and highly dispersed platinum nanoparticles can counteract Ostwald ripening. [2,6]In this study we show platinum particles deposited via ALD, which are highly dispersed and show a monodisperse size distribution. We further show TiO2-overcoatings to protect the carbon.Literature:[1] J. C. Meier, Beilstein J. Nanotechnol., 2014, 5, 55-67. [2] W-J. Lee, Adv. Mater. Interfaces, 2019, 6 1901210. [3] B. J. O’Neill, ACS Catal., 2015, 5, 1804. [4] W. W. McNeary, Appl. Catal. B, 2019, 254, 587-593. [5] Q. Liu, Chem. Soc. Rev., 2022, 51, 188-236. [6] Z. Xu et al., Appl. Catal. B, 2012, 111-112, 264.

Regioselective Organocatalyzed Monochlorination of Arenes with Electrophilic Chlorosulfoniums

AbstractThis manuscript presents a regioselective chlorination of arenes, yielding almost exclusively the monochlorinated product. It tolerates free hydroxy groups, 1°, 2° and 3° amines, and carboxylic acids, among other polar and nonpolar functional groups, as well as mono‐ and polysubstituted aromatic rings. Additionally, the utilization of chlorosulfonium salts as the chlorinating agent is demonstrated. The method emerges as an alternative to other processes where organic byproducts must be separated from the reaction mixture. In addition, the main byproducts are gaseous materials such as CO and CO2. This publication introduces the application of sulfoxides, oxalyl chloride, and aqueous hydrogen peroxide as the chlorination mixture.

On the microstructure and CO2 reactivity of tar–impregnated charcoal for cokemaking

Using charcoal in coke production offers a potential solution to mitigate CO2 emissions in the steel industry. However, incorporating charcoal into the cokemaking process encounters significant challenges, primarily due to its high reactivity towards CO2. The primary objective of this study was to gain a comprehensive understanding of the approach of blending charcoal with coal tar as a means of enhancing this material addition in cokemaking. The impact of tar impregnation on charcoal was assessed using optical and scanning electron microscopy, as well as CO2 reactivity. Results show that charcoals produced from impregnation followed by pyrolysis were significantly less reactive towards CO2, mainly due to pore filling and surface area reduction. Furthermore, charcoal's effect on coke quality was evaluated from laboratory coke samples produced without charcoal (reference) and with additions of 5 wt% (as received and tar-impregnated). Results from CRI/CSR tests showed that coke quality was sharply degraded due to as-received charcoal characteristics, while in contrast, coke with tar-impregnated charcoal achieved much better results, close to reference coke. This enhancement is primarily attributed to the reduced surface area resulting from impregnation and the inherently low reactivity of the pyrolyzed tar, which effectively acts as a barrier against material gasification.

Reaction mechanism of exfoliation degree and high temperature surface oxidation metamorphism of 2D Ti3C2Tx on thermal decomposition of various energetic materials

Achieving higher and faster energy release processes is a major research goal for energetic materials (EMs). Typically, EMs enhance their overall performance by incorporating catalysts. The novel two-dimensional layered MXenes, such as Ti3C2Tx, have shown significant potential as additives for ammonium perchlorate (AP). However, there is limited research on the impact of the exfoliation degree and high temperature oxidation of Ti3C2Tx MXene catalyst on the pyrolysis and combustion of different types of EMs. In this study, ultrathin Ti3C2Tx (U–Ti3C2Tx) MXene with a high exfoliation degree of approximately 20–80 nm was obtained through hydrofluoric acid (HF) etching, dimethyl sulfoxide (DMSO)-assisted layer expansion and ultrasonic peeling. The catalytic performance of MXenes on the thermal decomposition of three types of EMs (dihydroxylammonium 5, 5′-bistetrazole-1, 1′-diolate (TKX-50), cyclotetramethylene tetranitroamine (HMX), and AP) was evaluated. Results showed that 4 wt% U–Ti3C2Tx can reduce the decomposition peak of TKX-50 by 33.6 °C and decreases the high temperature decomposition (HTD) peak of AP by 45.5 °C, indicating superior catalytic performance compared to non-exfoliated Ti3C2Tx MXene. However, it had insignificant effect on HMX. Surface chemical analysis, electrochemical characterization, thermal decomposition of gaseous products analysis and material studio simulation all confirmed that high exfoliation U–Ti3C2Tx MXene exhibited better stability and electrical conductivity, facilitating the acceleration of the H+ transfer process and rapid gas release from EMs. Additionally, ignition tests demonstrated that high exfoliation U–Ti3C2Tx could effectively participate in the ignition process of EMs. The characterization and thermal analysis of Ti3C2Tx products after high temperature and oxidation treatment indicated that the catalytic activity is weakened due to high temperature crystal collapse and surface oxidation to TiOx metamorphism. This study provides new insights for the application of MXene catalysts in EMs.

Ni-WC/Al2O3 and Ni-WC/MgWO4/MgAl2O4 catalysts for resource recovery via pyrolysis combined with the dry reforming of plastics (PCDR)

Plastic waste (PW) is currently one of an environmental threat. Despite the increasing share of recycled plastics, their disposal remains high. Therefore, there is a high demand for new PW management systems. Among them, pyrolysis combined with dry reforming (PCDR) is an advantageous solution because it allows for resource recovery in the form of gas and liquid fuels, with simultaneous utilization of CO2. To date, catalysts based on Ni, Co, and noble metals supported on metal oxides have been examined. However, these catalysts suffer from quick deactivation due to coking and sintering. Therefore, testing other materials for PCDR is of particular importance. In this regard, Ni-WC/Al2O3 and Ni-WC/MgWO4/MgAl2O4 were investigated as potential PCDR catalysts. The catalysts were characterized by BET, BJH, XRD, CO2-TPD, H2-TPR, SEM, TEM, TG and DTG. The catalytic activity was evaluated in a two-step PCDR process using low-density polyethylene (LDPE), polystyrene (PS), polyethylene terephthalate (PET), and simulated waste plastic (SWP). The structure of the polymer strongly determines the yields of gas, liquid, and solid products. The highest yield of synthetic gas generation was observed for Ni-WC/MgWO4/MgAl2O4 and was 48.20 ± 2.41 mmol/gp. Different origins of the structural changes including oxidation or coking were observed for different plastics. PCDR of PET led mainly to oxidation, LDPE to the coking deposition. Catalysts after the process with PS were characterized by preservation of crystalline structure. The results indicate a high potential of carbide catalysts in the recovery of gaseous and liquid raw materials.

Parametric optimisation and performance evaluation of gasifier-CI engine on dual fuel and dual feed material gasification

Gasification-based energy derived is one of the appealing resources for producing heat and power generation. The objective of this paper is to conduct an experimental study on downdraft air co-gasification of Madhuca longifolia wood and Indian low-grade coal (50:50 wt %) to generate producer gas and its application in dual-fuelled mode CI engine. Besides, the optimisation using the response surface methodology (RSM) has been applied to Gasifier-Engine to determine the best engine performance and emission response by optimising the input variables, i.e. gasifier equivalence ratio, engine compression ratio, and engine load. The RSM-based analysis predicted that optimum input operating parameters could be attained for co-gasification for Equivalence ratio (ER), compression ratio (CR), and engine load (EL) at 0.43, 16, and 100%, respectively. Based on optimal input variables, the performance response values of the gasifier-engine are 29.52% Brake thermal efficiency (BTE), 3.30 kW Brake power (BP), 0.3851 kg/kWh Brake specific fuel consumption (BSFC), 0.0186 vol% CO, 0.958 ppm UHC, 0.9768 vol % CO2, and 109.415 ppm NOx. The results show that the projected regression model has a high accuracy of R2 > 90% and a high correlation coefficient of 0.8927.

Impact of Precursor Compounds Associated with Long-Range Transport in the East Asia Region—Variation in CO/CO2 and VOCs

In this study, the impact of long-range transport, one of the factors contributing to the presence of PM2.5, was examined, and an analysis of marker compounds associated with its long-range transport was conducted. Aerosol optical depth, wind field, CO/CO2 back-trajectory analysis, and satellite observation results were performed to determine PM2.5, volatile organic compound (VOC), CO, CO2, SO2, O3, NO, NO2, and NH3 levels at an orchard located in Jeollabuk-do, Republic of Korea. The characteristic of long-range transport at the observation area was evaluated during the research period. The concentrations for long-range transport based on concentration changes in gaseous materials and composition changes in PM2.5 were analyzed. A back-trajectory analysis for the ratio of CO to CO2 with satellite observation results was used to identify long-range transport. Furthermore, the proportionality between the ratio of 1,2-dichloroethane to naphthalene in VOCs and the quantity of precursor compounds linked to long-range transport were observed.

Dose analysis of nearby residents and workers due to the emission accident of gaseous radioactive material at the spent resin mixture treatment facility

The dose from a possible accident at a microwave-based spent resin mixture treatment facility that was to be installed and operated at the Wolsong nuclear power plant was analyzed to evaluate the radiological safety prior to its installation and operation. The dose to which workers and nearby residents are likely to be exposed was calculated based on the atmospheric dispersion and deposition factors using the XOQDOQ code. The highest atmospheric dispersion factors were 1.349E-05 s/m3 (workers) and 1.534E-06 s/m3 (residents). The highest doses due to emissions from the mock-up tank before operation were 1.91E-06 mSv (workers) and 1.78E-07 mSv (residents). Even after 3 h of operation, emissions from the mock-up tank had the greatest impact ranging from 4.63E-08 to 1.24E-06 mSv (workers) and 2.74E-10 to 1.16E-07 mSv (residents), respectively. The doses were 7.09E-09–4.55E-07 mSv and 4.18E-11–4.25E-08 mSv at 4–5 h of operation, and the maximum doses after operation reached 5.69E-07 mSv and 5.31E-08 mSv for the workers and residents, respectively.Even at the exclusion area boundary (EAB), 4.76E-08–9.51E-07 mSv (annual dose:9.52E-05–1.90E-03 mSv/y) was below the dose limit of the EAB, and the safety of the facility installation inside the NPP was confirmed.