Transport Of Radioactive Materials Research Articles

The influence of cooling rate on condensation of iron, aluminum, and uranium oxide nanoparticles

Fundamental observations of particle size distributions are needed to develop models that predict the fate and transport of radioactive materials in the atmosphere following a nuclear incident. The extent of material transport is influenced by the time scales of particle formation processes (e.g., condensation, coagulation). In this study, we investigated the influence of cooling time scales on size distributions of uranium, aluminum, and iron oxide particles that are synthesized separately under identical run conditions inside the controlled environment of an argon plasma flow reactor. Two distinct temperature distributions are imposed along the flow reactor by varying the argon flow rate downstream of the plasma torch. The vaporized reactants of uranium, aluminum, and iron are cooled from about 5000 K to 1000 K before they are collected on silicon wafers for ex situ scanning electron microscope analysis. The microscope images show that the sizes of the largest aluminum and iron oxide particles heavily depend on the cooling time scales, whereas significant size variation with cooling rate is not observed for uranium oxide particles. In addition, the size distribution of aluminum oxide particles exhibits the broadest range among all three metal oxides studied. We performed simulations of particle size distributions using a kinetic model that couples gas phase oxidation chemistry with particle formation processes, including nucleation, condensation, and coagulation. The model results demonstrate the strong sensitivity of particle size distribution to different cooling histories (i.e., temperature vs residence time) along the flow reactor. The kinetic model also helps identify directions for future research to improve the predictions.

Operating conditions of container cars in railway trains of special formation

Abstract. The article considers main technical characteristics, indicators of dynamic qualities and parameters of braking effciency of special railway rolling stock of container cars (container transporters) intended for the transportation of radioactive materials — spent nuclear fuel. In accordance with the current regulatory documents of JSC Russian Railways, it is currently allowed forming special trains exclusively from container transporters of any one type, which is associated with the peculiarities of the technology for handling and transporting spent nuclear fuel, which is within the competence of the state corporation Rosatom. However, this signifcantly increases the timing of the delivery of special trains due to the need to wait for the readiness of transporters, due to the non-simultaneous delivery of any one type of assembly kits with spent nuclear fuel. The practice of handling has shown that the transportation of some types of spent nuclear fuel can be carried out with a combination of the transport operation, which implies the combination of various types of container transporters in one echelon, but at the same time it is necessary to correct certain regulatory documents of Russian Railways. For this purpose, at the request of the Rosatom corporation, a necessary set of experimental works was carried out. Authors presented results of control running dynamic, stationary and running braking tests of container transporters of various types, following as part of the same echelon, on the infrastructure of the Test Loop of JSC “VNIIZHT”, including when running along the frst ring track and along various combinations of turnouts along a tangent line (main) and lateral directions. It has been experimentally proved that it is possible to operate container transporters of various types as part of the same echelon in compliance with the conditions for ensuring traffc safety in accordance with the standards of dynamic qualities and braking effciency. Based on the test results, a regulatory document of JSC Russian Railways was developed — the Regulation on the conditions for joint operation of special freight cars (transporters) as part of one echelon, approved by the order of JSC Russian Railways dated July 22, 2021 No. 1591/r. components. Interstate standard, put into effect as nat. standard of the Russian Federation by order of the Federal Agency for Technical Regulation and Metrology dated March 17, 2016 No. 162-st. Moscow, Standartinform Publ., 2016, 54 p. (in Russ.).

Radioactive impact on Iran and the world from a postulated accident at Bushehr Nuclear Power Plant

Chernobyl and Fukushima nuclear accidents showed that nuclear accident is a global concern. Dispersion and faraway transportation of radioactive materials under atmospheric conditions are the main goals of this paper. Radioactive materials have a lot of damages, undesirable and dangerous long-term effects on the environment and human health. Therefore, in this paper, the simulation of transport, dispersion and deposition of radioactive materials released from a postulated accident in Bushehr Nuclear Power Plant have been studied using HYSPLIT. The postulated accident for Bushehr Nuclear Power Plant is designed based on world's largest nuclear accident, the Chernobyl accident. In this study, it is assumed that the postulated accident in Bushehr nuclear plant occurred on March 21, 2015. The simulation results show that in the period of one month, nuclear pollution resulting from this accident would affects almost the whole of Iran. The amount of radioactive materials deposition is very high in some cities of Iran. The most deposition of radioactive materials would occur in Bandar Bushehr and Ahvaz. In these cities, the maximum deposition is related to the second day of the accident, which are: 1.55×108Bq/m2 and 1.06×106Bq/m2, respectively. During this period, in addition to Iran, even most Asian countries, North America, Europe continent and Africa are affected by nuclear pollution while the most pollution is related to Asia, North America and Europe, respectively. Radioactive materials after passing from the continents come back to the East Asian again. In Asian countries after Iran, the maximum deposition of radioactive materials is related to Turkmenistan that the deposition value is 1.78×105Bq/m2 for the second day of the accident. In continent of America, the most nuclear pollution is related to the state of Arizona. In this state, the maximum deposition is 1.00×105Bq/m2 on the fifteenth day of the accident. In Europe, the maximum deposition is in Ukraine and it is 4.16×103Bq/m2 on 12 days after the accident. In this accident, radioactive materials would contaminate the most of Northern hemisphere and also would influence the southern hemisphere in very negligible amount.

Detection of Illegal Movement in Radioactive Material Transportation Security Systems

The loss and theft of radioactive material in transport can be attributed to the illegal movement. In order to distinguish it from the movement caused by the turbulence of the transportation vehicle, this paper proposes the criterion of “illegal movement” as the movement of radioactive materials outside the transportation compartment. Since the interior of the compartment is generally a metal environment, this paper proposes wireless signal strength data as a sensing method. The wireless signal strength data is filtered and converted into distance data. We construct a spatial triangle perpendicular to the top and sides of the compartment based on the distance data. When the radioactive material is inside the compartment, the angle between its corresponding point and the top plane of the compartment is less than 90°. Once it moves out of the compartment, the angle will be greater than 90°. Based on this, a sensing method of “illegal movement” based on spatial triangles is proposed. The simulation research shows that the scheme proposed in this paper is feasible.

Current and Prospective Radiation Detection Systems, Screening Infrastructure and Interpretive Algorithms for the Non-Intrusive Screening of Shipping Container Cargo: A Review

The non-intrusive screening of shipping containers at national borders serves as a prominent and vital component in deterring and detecting the illicit transportation of radioactive and/or nuclear materials which could be used for malicious and highly damaging purposes. Screening systems for this purpose must be designed to efficiently detect and identify material that could be used to fabricate radiological dispersal or improvised nuclear explosive devices, while having minimal impact on the flow of cargo and also being affordable for widespread implementation. As part of current screening systems, shipping containers, offloaded from increasingly large cargo ships, are driven through radiation portal monitors comprising plastic scintillators for gamma detection and separate, typically 3He-based, neutron detectors. Such polyvinyl-toluene plastic-based scintillators enable screening systems to meet detection sensitivity standards owing to their economical manufacturing in large sizes, producing high-geometric-efficiency detectors. However, their poor energy resolution fundamentally limits the screening system to making binary “source” or “no source” decisions. To surpass the current capabilities, future generations of shipping container screening systems should be capable of rapid radionuclide identification, activity estimation and source localisation, without inhibiting container transportation. This review considers the physical properties of screening systems (including detector materials, sizes and positions) as well as the data collection and processing algorithms they employ to identify illicit radioactive or nuclear materials. The future aim is to surpass the current capabilities by developing advanced screening systems capable of characterising radioactive or nuclear materials that may be concealed within shipping containers.

Analysis and evaluation of radioactive material transport monitoring in Beijing from 2006 to 2020

Transport monitoring is an important link in the transport process of radioactive materials, involving the whole process, that is, before departure, during transportation and after arrival. To do well in transport monitoring, radiation monitoring organizations need to actively participate in the work, and also need to do a good job in the supervision of radioactive materials transport monitoring. Beijing is one of the radioactive materials distribution centers in China, the monitoring workload is large, the number of monitoring reports is large, the number of packages by air transportation is relatively large, and the transportation and monitoring for medical use is dominant. Through the introduction of radioactive materials transportation monitoring work, and analysis of 2006—2020 radioactive materials transportation monitoring situation, this paper discusses the problems that need to be paid attention to in the monitoring work and the ways to deal with them, so as to provide ideas for radiation monitoring organizations to carry out monitoring work and manage the transport of radioactive materials well. 摘要：运输监测是放射性物品运输过程中重要环节, 涉及起运前、运输中及抵达后全过程, 要做好运输监测工作, 需要 辐射监测机构积极参与, 还需要做好放射性物品运输监测工作的监督。北京市是国内放射性物品集散地之一, 监测工 作量大, 出具监测报告数量多, 采用航空运输方式的货包数量占比较大, 医用用途运输监测为主导。本文通过介绍放 射性物品运输监测工作开展, 并分析2006—2020年放射性物品运输监测情况, 探讨监测工作中需关注问题及处理方 式, 为辐射监测工作机构开展监测工作及做好放射性物品运输管理提供思路。

Evaluating the impact of airborne radionuclides caused by the Fukushima nuclear accident on China based on global atmospheric dispersion

In response to the Fukushima nuclear accident in Japan, the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) and other countries have conducted extensive monitoring and research. This article used an improved global atmospheric dispersion model WRF-Chem to simulate the global transport of radioactive materials released by the Fukushima nuclear. And mainly analyzed its impact on China, using the monitoring data of the environmental protection department to analyze the environmental level of atmospheric radioactivity and evaluate the model. The results showed that the radioactive plume spread from west to east, across the Pacific Ocean, the American continent and Europe, and finally, it spread to the entire northern hemisphere. China first detected I-131 in Heilongjiang Province on March 23, and until April 3, all provinces in China detected radionuclides from Fukushima nuclides. Combining the time taken by the radioactive plume to reach various parts of China, it can be inferred that the radioactive material can reach China through three routes, which may be the main reason why the leaked nuclides reach China and Europe in the same time. The global proliferation model tested by the FDNPP accident can provide a reference for the potential radiation impact of nuclear power plants, help understand the potential threat of future nuclear accidents, and provide support for nuclear accident monitoring and emergency measures.

A new method for detecting the radioactive materials using X or [formula omitted]-ray cargo inspection systems

The proliferation of nuclear technology applications has made the illicit trafficking of radioactive sources a serious threat. Currently, several methods have been developed to control the transport of radioactive materials, including the use of monitoring gates, portable detectors, dosimeters, etc. In this work, a new method is proposed to be implemented on the X- or gamma-ray vehicle inspection systems to enable them to detect the hidden radioactive materials inside the trucks or cars. The main goal of the work is to introduce the method on a lab scale from the qualitative point of view. In this method, post-processing is done on the images acquired from a linear array detector to find the hidden radioactive sources inside the scanned objects without the need for additional inspections by other monitoring tools.

Single-Vehicle Transportation Security System of Radioactive Materials Based on Group Relationship to Prevent Loss and Theft

For loss and theft in the transport of radioactive materials by a single vehicle, this article summarizes the characteristics of “illegal movement” and establishes a security system that senses its inter-relationship and responds though the group network relationship. The security system reminds the vehicle crew through on-site response and linkage response. A failure detection method for on-site response is proposed, that is, the push model is used first, and when the measurement results are suspected, the pull model is used to further confirm the failure. The failure detection for linkage response adopts the push model. According to the different security requirements of the basic and enhanced transportation, the principle of setting the timeout threshold in the failure detection algorithm is proposed. In the enhanced type, the value is smaller, otherwise the value is larger. A specific timeout threshold quantification scheme is proposed. Experiments show that the method proposed in this article is effective.

The security of transport of radioactive and nuclear material in Belgium

This article describes and assesses the security of transport of radioactive and nuclear material in Belgium that has been boosted after the terrorist attacks in Brussels in 2016. The article looks at the different possibilities of terrorist attacks on transports of radioactive and nuclear material and the possible consequences: theft of radioactive material for use in a radioactive exposure device, a radioactive dispersal device, or an improvised nuclear weapon; or a conventional attack on a transport, releasing radiation into the environment. The focus on insider threat is a step forward, but it may not divert attention from regularly updating security measures against outsider threat. Some recommendations are provided to ensure continuous improvement in the transport of radioactive and nuclear material.

Assessing the management system to demonstrate the safe of transport of radioactive material

Radioactive materials are used for medical purposes, to avoid greenhouse gas effect in energy production plants, food and other products sterilization, research and sophisticated measurement technologies. Transport of radioactive material involves a range of actors each one having specific responsibilities for safety. Through Management System, consignors and carriers fulfil objective evidences that safety requirements are met in practice, while compliance assurance programs allow regulatory bodies and/or competent authorities to demonstrate to society that public, workers and environment are protected. According to IAEA, safety has to be achieved and maintained through an effective management system. This system should integrate all elements of management so that requirements for safety are established and applied consistently with other requirements, including those related to human performance, quality and security, and so that safety is not committed by other requirements or demands. CNEN, the Brazilian Regulatory Body for the safe transport of radioactive materials, adopt international standards to establish safety requirements deemed relevant for protection of health and minimization of danger to life and property, and to provide for the application of these standards. Seeking for continuous improvement, the adherence of the practices adopted by Transport Safety Unit (TSU) against the recommendations from the IAEA was assessed. This assessment led to the elaboration of proposals for improvement as well as the identification of good practices. The methodology used to perform this assessment was the SARIS methodology, developed by the IAEA. This paper will describe the most relevant findings of this study.

Illegal handling with radioactive materials: investigation and criminal liability

This article covers current issues of investigating the illegal handling with radioactive materials. Attention is also paid to the problems of criminal qualification of acts related to the illegal handling with the materials mentioned above. The conditions for exemption from criminal liability in the case of acquisition, carrying, storage, use, transfer, modification, destruction, spraying or destruction of radioactive materials (sources of ionizing radiation, radioactive substances or nuclear materials in any physical state in the installation or production or otherwise) without the permission provided by law are disclosed. Emphasis is put on the fact that the use of radiation technologies in production, medicine and other spheres of life necessitate the development of appropriate safety measures, compliance with which will save the lives and health not only of individuals but also of the population in a whole and the environment. It is argued that updating the methods of learning criminal offenses under investigation, which are becoming more daring and carefully prepared, requires the development of modern forensic tools and methods to combat them. It is noted that law enforcement agencies need the help of specialists in nuclear physics, radiology and other fields of knowledge at the initial stages of the investigation of the above-mentioned crimes. Therefore, the purpose of the study was to determine the areas of use of specialist assistance in the investigation of radioactive materials illegal handling, as well as to highlight current issues of criminal qualification of these acts, which most often occur in law enforcement. It is noted that in Ukraine, nuclear forensics is not developed enough and requires the joint work of forensic scientists and experts from various fields of knowledge, which will allow to develop list of effective recommendations and algorithms for law enforcement officers in investigating criminal offenses related to trafficking in radioactive materials. Emphasis is placed on the fact that the use of special devices in the investigation of examined crimes is due not only to the tasks of investigation but also safety when working with radioactive substances, as it depends on timely detection and measurement of radiation levels performed by special devices. It is concluded that in the investigation of the examined crimes the assistance of specialists in the field of nuclear physics, radiology, chemistry, medicine is needed in the following areas: development of radiation and hygienic regulations for employees of the investigative and operational group who work with radioactive materials; conducting a mandatory medical examination of all participants in the investigative (search) actions after work with such materials; conducting trainings with law enforcement officers in order to obtain basic knowledge about radioactive materials, rules for handling them, including the ability to use protective equipment; development of personal protective equipment, means of detection, fixation and retrieval (including packaging and transportation) of radioactive materials.

Крос-верифікація Монте-Карло кодів Geant4 та MCNP6 для мюонної томографії

Muon tomography is a promising detection technology that uses natural radiation, the muons of cosmic rays. In the last decade, a significant number of scientific papers have appeared that investigate the possibility of using muon tomography in various fields of science and technology. Especially remarkable is the considerable potential of this technology for detecting the illegal transport of radioactive materials and for no-invasive testing of the integrity of spent nuclear fuel in dry storage facilities for such fuel. For the implementation of muon tomography technology, the process of preliminary modeling of the experimental detector facility is important, which also requires verification of the obtained calculation results. For this purpose, the well-known Monte Carlo codes MCNP and Geant4 are mainly used. This results of the first cross-verification studies of MCNP6 and Geant4 codes are demonstrated in the paper. The study was performed on simple models for different materials and for different energies of the muons bombarding the research object. The recommended QGSP_BERT physics library was used in the Geant4 code. In the MCNP6 code, the recommended settings for cosmic particle simulations were used. The calculations showed that for low-energy muons, both codes give results that agree well with each other. This can be explained by the fact that similar libraries of evaluated nuclear data are used in the low-energy range. Regarding the muons of intermediate energies, there is a significant difference between the two codes, which may indicate differences in physical models. The modeling of high-energy muon transfer has better agreement between MCNP6 and Geant4 codes than for intermediate-energy muons, but significant differences are still observed for heavy nuclei.

Implementation of safety and security standards for high dose rate brachytherapy sealed radioactive source used in a medical radiation facility

ObjectiveTo provide guidance on basic concepts and elements for radiation safety and security measures for a HDR brachytherapy sealed radioactive source in a medical radiation facility. MethodsBrachytherapy sources are Category 2 (High risk-very dangerous) radioactive source and Security Level B applied to cover the range of security measures needed for the associated risk with remote afterloading HDR brachytherapy sources. These security measures were applied based on a risk informed graded approach. A series of in-build and operational safety measures were implemented for equipment and radiation installation. ResultsThe medical radiation facility equipped with adequate radiation protection, detection and monitoring equipment such as survey meter, digital contamination monitor, gamma zone monitor, digital radiation monitor, personnel dosimeter, pocket dosimeter, long handled forceps, shielding material and emergency source storage container etc. to deal with radiological incidences. The contingency plan with security objectives for incidents and procedures for action was prepared in order to implement response function to fulfill the goal of adequate security of radioactive source. The emergency response plan documented against emergency scenarios during transport, loss of radioactive source, theft, sabotage, natural calamities/disasters such as fire, flood and earthquake. ConculsionsThe paper provides various radiation safety and security aspects for the HDR brachytherapy. The HDR brachytherapy radioactive sources are Type A packages. Transport of radioactive material is the responsibility of consignors, consignee and carriers under the legislation, supervision and control of regulatory authority.

Vehicle Transport Security System Based on the Self-Security Intelligence of Radioactive Material

This paper proposes to design security measures based on the radioactive material package as the basic unit. The principle of four-layer defense in depth is put forward. Based on the concept of self-security intelligence, combined with out-of-vehicle monitoring, in-vehicle monitoring, and Beidou positioning technology, a security system for transport of radioactive materials was designed. It realized the perception, early warning, delay, and alarm functions and greatly improved the security.

Challenges of implementing the policy and strategy for management of radioactive waste and nuclear spent fuel in Indonesia

Indonesia has policies and strategies for the management of radioactive waste and spent nuclear fuel that arises from the use of nuclear research and development facilities, including three research reactors, and the use of radioisotopes in medicine and industries. The Indonesian government has provided extensive facilities such as an independent regulatory organization (BAPETEN) and a centralized radioactive waste management organization (CRWT-BATAN). Further, the presence of regulations and several international conventions guarantee the protection of the public from all risks due to handling radioactive waste and spent nuclear fuel. However, the sustainability of radioactive waste management in the future faces various challenges, such as disposal issues related to not only to site selection but also financing of radioactive waste management. Likewise, the problem of transportation persists; as an archipelago country, Indonesia still struggles to manage the infrastructure required for the transport of radioactive materials. The waste from the production of the radioisotopes, especially from the production of 99Mo, requires special attention because BATAN has never handled it. Indonesia should also resolve the management of NORM from various activities. In Indonesia, the definition of radioactive waste does not include NORM. Therefore, the management of this waste needs revision and improvement on the regulations, infrastructure, and technology.

Effect of adsorption, radioactive decay and fractal structure of matrix on solute transport in fracture.

Reservoir contamination by various contaminants including radioactive elements is an actual environmental problem for all developed countries. Analysis of mass transport in a complex environment shows that the conventional diffusion equation based on Fick's Law fails to model the anomalous character of the diffusive mass transport observed in the field and laboratory experiments. These complex processes can be modelled by non-local advection-diffusion equations with temporal and spatial fractional derivatives. In the present paper, fractional differential equations are used for modelling the transport of radioactive materials in a fracture surrounded by the porous matrix of fractal structure. A new form of fractional differential equation for modelling migration of the radioactive contaminant in the fracture is derived and justified. Solutions of particular boundary value problems for this equation were found by application of the Laplace transform. Through the use of fractional derivatives, the model accounts for contaminant exchange between fracture and surrounding porous matrix of fractal geometry. For the case of an arbitrary time-dependent source of radioactive contamination located at the inlet of the fracture, the exact solutions for solute concentration in the fracture and surrounding porous medium are obtained. Using the concept of a short memory, an approximate solution of the problem of radioactive contaminant transport along the fracture surrounded by the fractal type porous medium is also obtained and compared with the exact solution. This article is part of the theme issue 'Advanced materials modelling via fractional calculus: challenges and perspectives'.

The Perils of a Half-Built Bridge: Risk Perception, Shifting Majorities, and the Nuclear Power Debate

Much of the risk perception literature relies on the important but unstated assumption that manipulating public opinion to conform to scientific assessments of risk could help the public and, in turn, policymakers make better decisions about whether and how to regulate. This paper argues that the assumption fails in the context of certain multilayered risks, or risks that pose tiered policy choices - not just whether to regulate in the first instance, but how to respond to derivative risks arising from the first set of regulatory changes. Examining the debate about the role of nuclear power in the United States' approach to climate change, the paper observes that first- and second-tier risks often differ in character, or require different types of regulatory solution (market-based versus command-and-control). Due to these variations, the public may hold starkly different views about regulation of each tier, and those views may be differently - that is, differently susceptible to persuasion. In the context of the nuclear power debate, this tiering of opinion has perverse implications. The first-tier risks of nuclear power are those associated with individual reactors, including the risks of accident or terrorist attack; the second-tier risks are those associated with mining, transport, processing, storage, and disposal of radioactive materials. Recent work asserts that despite entrenched public fear of nuclear power, it may be possible to induce people to support construction of low-emissions reactors as a strategy for mitigating climate change. But even if policymakers could employ the risk education strategies discussed in the literature to shift public opinion in favor of economic incentives for nuclear reactor development, there is no reason to think such strategies would be equally effective at changing attitudes toward second-tier risks and the command-and-control regulations necessary to address them. To the contrary, many people would likely continue to oppose certain types of government action on these latter problems, even assuming the complete success of the hypothesized first-tier education strategy. As a result, the United States could find itself with a thriving nuclear power sector, but without the political will to address the grave collateral risks. These observations lead to two conclusions, one related to the nuclear power example, and one to risk regulation more broadly. First, differently sticky public attitudes toward first- and second-tier nuclear risks and their regulatory solutions may defeat any effort to respond to climate change by significantly and safely increasing U.S. reliance on nuclear power. Second, efforts to change public risk perceptions may not advance a regulatory agenda, and may even prove counterproductive. Specifically, where multiple risk layers exist, a successful first-tier education effort and consequent policy changes could create or expose second-tier risks that defy regulatory solution, leaving policymakers stranded at the abrupt and unexpected end of a half-built bridge. Depending on the gravity of the second-tier risks, this regulatory dead end could be one that neither policymakers nor the public would have chosen ex ante.

Experimental Investigation of Uranium Volatility during Vapor Condensation.

The predictive models that describe the fate and transport of radioactive materials in the atmosphere following a nuclear incident (explosion or reactor accident) assume that uranium-bearing particulates would attain chemical equilibrium during vapor condensation. In this study, we show that kinetically driven processes in a system of rapidly decreasing temperature can result in substantial deviations from chemical equilibrium. This can cause uranium to condense out in oxidation states (e.g., UO3 vs UO2) that have different vapor pressures, significantly affecting uranium transport. To demonstrate this, we synthesized uranium oxide nanoparticles using a flow reactor under controlled conditions of temperature, pressure, and oxygen concentration. The atomized chemical reactants passing through an inductively coupled plasma cool from ∼5000 to 1000 K within milliseconds and form nanoparticles inside a flow reactor. The ex situ analysis of particulates by transmission electron microscopy revealed 2-10 nm crystallites of fcc-UO2 or α-UO3 depending on the amount of oxygen in the system. α-UO3 is the least thermodynamically preferred polymorph of UO3. The absence of stable uranium oxides with intermediate stoichiometries (e.g., U3O8) and sensitivity of the uranium oxidation states to local redox conditions highlight the importance of in situ measurements at high temperatures. Therefore, we developed a laser-based diagnostic to detect uranium oxide particles as they are formed inside the flow reactor. Our in situ measurements allowed us to quantify the changes in the number densities of the uranium oxide nanoparticles (e.g., UO3) as a function of oxygen gas concentration. Our results indicate that uranium can prefer to be in metastable crystal forms (i.e., α-UO3) that have higher vapor pressures than the refractory form (i.e., UO2) depending on the oxygen abundance in the surrounding environment. This demonstrates that the equilibrium processes may not dominate during rapid condensation processes, and thus kinetic models are required to fully describe uranium transport subsequent to nuclear incidents.

Development of the Theoretical-Practical Model of Protection of the Means of Transport of Radioactive Materials

Ensuring the safety of transportation of radioactive materials is of great importance due to the presence of the potential risk of damage to people, the environment and property during transportation, loading and unloading operations and intermediate storage. This article describes the means of storing liquid radioactive waste, as well as the process of their transportation. During the study, emergency situations during the transportation of LRW were considered. A security model has been developed for the storage of radioactive materials during multimodal transport.