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DOE OSTI2019

Remediation of Irradiated Graphite Using Microorganisms Isolated from Oil Contaminated Soil - 19643

The deployment of nuclear energy globally is hindered by the fear cleared by nuclear reactor disasters such as the Chernobyl and Fukushima reactor meltdowns. Additionally, accumulation of radioactive waste globally will, in the near future, present a significant threat to humans and the environment. Notably, the majority of nuclear waste from the energy generation industry is generated as Low Level Waste (LLW) in which the small radioactive component renders the bulk of the waste unsuitable for conventional treatment and disposal. In the case of radioactive graphite, the small radioactive component comprising radiocarbon-14 (C-14) and metallic pollutants can be removed to allow safe disposal or reuse as of the graphite. In the current study, mixed-cultures of organisms isolated from oil contaminated sites showed potential of selective bioaccumulation of C-14 from a powdered C-12/C-14 graphite matrix. The study was conducted in a continuously mixed reactor (growth vessel) constructed from Pyrex panels (30 cm x 20 cm x 15 cm) with finely ground graphite as the principal carbon source (1500-2000 mg.L{sup -1}) and spikes of glucose (500 mg.L{sup -1} every 48 hours). The growth vessel was connected to a biofilter unit by submersible pump where particulate matter was isolated for further analysis. Results showed that approximately 68% more C-14 was released from ignited dry cells than from respiration product. C-14 accumulated in cells corrected using a trap filter system, with a marked decrease of C-14 in carbon dioxide than vegetative suspended cells in the main tank. The only mechanism that could account for the differential C-14 distribution between the liquid medium and cells was possible fractionation during uptake of carbon compounds. The discriminating factor suggested in this study is the kinetic isotope effect (KIE) which allows heavier atoms to have different affinities for reaction sites on catalysis and biocatalysis. (authors)

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DOE OSTI2017

Mitigation of Radioactive Waste By Sampling and Analyzing The Affected Area and Efficient Use of Different Detectors - 17400

The paper summarizes the way by which the mitigation of the radioactive waste during events like decommissioning of nuclear power plants, or during a nuclear disaster can be done so that the rehabilitation process for flora and fauna can begin in a natural manner. The paper describes the problems faced during ER operations in the developing countries and need of international committees in these areas. The paper suggests marking of the radioactive areas which can be used for controlled personnel access and which can be useful for monitoring purposes, while also focusing on the need of proper knowledge while handling detectors in ER operations for successful site characterization. It also highlights the importance of bio-indicators in these operations and also gives a description of various detectors used widely and their related significance for ER operations. The paper gives an overview of the planning and site characterization stages that follow in the environmental remediation. Planning stage should consider: 1. The impact on the ecosystem and human beings and the risk of spreading of the radionuclides. 2. The financial aid in hand for detectors, machinery and skilled labor. As the planning stages develop, the very first thing is the survey of the site. Site investigation should be carried out in all aspects including meteorology, geology, and hydrology, seismicity, geomorphology and the other aspects depending on site for a certain period of time. A site characterization should take: 1. The amount of damage occurred to the environment in the nearby region. 2. The distribution, character and the extent to which radioactivity has been dispersed. 3. The amount of risk that will be involved for personnel working in the field. 4. The precision of data collected that is to be used as input for further processes. In the developing countries, the central governmental bodies play a pivotal role in providing funds internally or from international bodies. The paper shows the effect how political issues effect the work progress of ER operations, that hamper the process and make people frustrated, who really work on the field. Paper provides the suggestion for the proper use of detectors in these countries where surveyors lack knowledge on what kind of detectors to be used while taking precision as a parameter. The table beside gives just a small picture of the large variety of detectors available today and tries to summarizes the main detectors with applications. There should also be a proper marking of the areas into different levels of radiation that will be helpful for work access control and monitoring personnel health. The paper also suggests of using bio-indicators in ER operation more often. The paper proposes to use site-specific bio-indicators which are very helpful in knowing the proper effect of the event in the environment. There is no single paved path for every situation that can lead to a successful ER. The planning should be done in such a way that the future work is not disturbed due to technical problems. In developing countries, political issues can hamper the progress of work and time remains a critical issue in such areas. The lack of proper knowledge for the use of detectors can affect the outcome of site characterization. Areas of the survey should be marked with different levels of activity for efficient monitoring of personnel's. The use of bio-indicators should be used more often and should be chosen as per the site. As they are a helpful tool in evaluating the work progress. (authors)

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DOE OSTI2019

Analysis of the Impact of Radiation on Cameras and Robotic Perception - 19242

Robotic systems are increasingly used for inspection, maintenance, and disaster assistance for nuclear power plants. These robots utilize increasingly high levels of autonomy to operate in environments that are unsafe for humans to operate the robot in or require more precise control over the robot than a human can offer. In these cases, the robot must include perception and computation components to autonomously sense and navigate through the environment to fulfill its mission. This difficult task is complicated by radiation interfering with sensors' operation. The impact of this interference is largely unexplored, as existing works on radiation interference on sensors focus on estimating the incident radiation, rather than how it impacts a robotic system using the sensor. In this work, we seek to quantify and describe the impact of radiation on cameras, and how the radiation affects robotic performance. In this paper we study cameras that are suitable for small, lightweight unmanned aerial vehicles (UAVs) that are increasingly deployed to fly in confined areas in emergencies, where the surrounding environment is unsafe for workers to operate. These small UAVs lack the payload capacity to carry significant radiation shielding, so any onboard sensors will be affected by radiation. In the case of cameras, this radiation appears as noise in the camera imagery. This noise will interfere with the UAV's operation, by obscuring obstacles and interfering with localization and optical flow algorithms that detect detailed features in the environment. To date, there is a lack of information on how the radiation noise in the camera image impacts the overall robot system performance Existing work focuses on estimating the amount of incident radiation by measuring the corruption in the images. However, these works suffer several shortcomings for robotic systems. First, a robot must be able to successfully navigate its environment during a successful mission, and merely quantifying the amount of radiation noise in an image does not adequately explain how it may interfere with higher level navigation and perception tasks. Second, radiation estimation procedures rely on focusing the camera on a known and static background. This is unsuitable for robotic exploration tasks, where the robot frequently moves around an unknown environment that may be dynamically changing. Our work contains two contributions that address these shortcomings. First, we conduct a detailed analysis of the noise radiation causes in cameras by exposing cameras that are commonly used on UAVs [e.g., small form factor complementary metal-oxide-semiconductor (CMOS) cameras] to varying levels of radiation that may be present in emergency scenarios. From this exposure, we quantify not only how much noise is present, but quantify its appearance. By quantifying the appearance and amount of noise in a camera image, researchers can design mitigation strategies for the corruption, so that their robotic systems can operate in these challenging environments. Second, we demonstrate how to leverage this experimental data in robotic simulations. Using data from the first set of experiments allows us to test and verify the robots in simulation. Using simulators allows us to verify the robots will perform as expected during critical times without needing expensive test equipment or damaging valuable robot prototypes. Other researchers using robots for exploration of irradiated environments will benefit from our research by incorporating similar noise models in their research. 1 Southwest Research Institute{sup R} is a registered trademark of Southwest Research Institute in the United States and/or other countries. This will increase the reliability of robotic systems prior to deployment in emergency situations, which will in turn increase their effectiveness and speed the development of robots that would otherwise need expensive and time-consuming test procedures to validate. (authors)

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