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All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Iodine Speciation Across the Length of the Hanford 200-UP-1 Operable Unit Radioiodine Plume and Biogeochemical Drivers of Speciation - 17270

In 1943, construction began on the first of nine nuclear reactors at the Hanford Site to produce plutonium for the development of atomic weapons for the Manhattan Project during World War II and throughout the Cold War. Over a production period lasting from 1944 to 1987, approximately 110,000 tons of nuclear fuel was processed. During the production period, billions of gallons of liquid nuclear waste and millions of tons of solid waste were produced. Approximately 4.7 Ci of radioiodine (I-129) was discharged to liquid disposal sites, during disposition of the waste. Following percolation of the liquid waste through the vadose zone, three large I-129 groundwater plumes have formed beneath Central Plateau Facilities including both 200 East and 200 West Areas. Analysis of I-129 plumes in the 200-ZP-1 Operable Unit (OU) (200 West Area) showed iodine speciation that was dominated by iodate even though iodide was thought to be dominant species in waste. Experimental results demonstrated that iodate interacts with calcite via a co-precipitation and/or adsorption mechanism. From sorption experiments performed on Hanford sediments, iodate interacted more strongly than iodide during adsorption experiments. These results would indicate that iodate migration would be retarded compared to iodide, but results from groundwater samples obtained from eight wells in the 200 ZP-1 OU did not support this hypothesis. Due to different chemical processes used during plutonium processing, iodine species in other plumes such as in the 200-UP-1 OU (200 West Area) may be different. In addition, species distribution may change longitudinally between the source area and the distal end of the plume. Groundwater samples will be taken at a location near the source, in the middle of the plume and at the distal end of the plume. These samples will be analyzed for iodine speciation using ion chromatography coupled to an inductively coupled plasma mass spectrometer. Results from the different samples will be compared to give an initial determination of species distribution at different locations along the plume. Data generated from these samples can then be used to inform the conceptual model that is being developed for iodine as part of an evaluation of remediation options for the 200-UP-1 OU. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Surface Modification of Rock-Forming Minerals of Diamond-Bearing Kimberlites under Interaction with Wastewater and Electrochemically Treated Water

The structural and chemical surface transformation of basic kimberlite-forming minerals (calcite, olivine, serpentine) under the contact with natural and waste mineralized water and products of electrochemical treatment of the water are studied using X-ray photoelectronic spectroscopy, scanning electron microscopy and X-ray spectral micro-analysis, and atomic force microscopy. It is found that contact with kimberlite extract and recycling water induces chemical modification of calcite surface, which consists in adsorption of hydrocarbon impurities, and chlorine- and silica-bearing compounds, majority of which are removed during interaction with the product of electrochemical treatment of recycling water. The change in the structural and chemical surface properties of rock-forming silicates, aside from adsorption–desorption of organic compound, is also connected with the distortion of nano-size layer structure after leaching of Mg, Fe and Si, and with the carbonatization of the surface.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Integrating Mindfulness with Human Performance in High Complexity Environments - 19498

This paper includes a survey of both scientific and technical literature studies of mindfulness interventions in a variety of industries and populations and proposes potential applications in complex nuclear waste operations. Mindfulness training techniques have been utilized in various forms for decades in high consequence work in both public and private enterprise. The traditional safety nomenclature has simply used different words to describe many of the same concepts that mindfulness practice addresses. Historically, human performance improvement (HPI) has focused on task, mission and error-likely conditions. These safety programs recognize that human behavior is the source of most errors and focus on identification of specific error precursors (mind not on task, incorrect mental picture, etc.). Workers in nuclear and related industries have been trained to recognize these error precursors but have received little training on what to do about them. The techniques of mindfulness align well with HPI programs currently utilized in commercial and government nuclear operations. Indeed, Chapter 5 of the Department of Energy Human Performance Improvement Handbook (DOE-HDBK-1028-2009) includes a discussion of mindfulness with respect to human performance. Mindfulness training supplements current performance improvement efforts by giving workers the tools to not just recognize error-likely conditions within themselves, but also gives them methods to mitigate them. The mindfulness practices presented here focus on self-awareness rather than task-awareness. Workers can apply these techniques in all aspects of their lives which in turn addresses many of the distractions previously identified as error precursors (stress at home or at work, physical discomforts, mind not on task, etc.). The application of mindfulness techniques through integration with established Integrated Safety Management Systems (ISMS) has the potential to improve the safe performance of nuclear waste operations and increase the breadth of organizational safety culture. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

Effective dialogue: Enhanced public engagement as a legitimising tool for municipal waste management decision-making

Highlights: • A review of public engagement in waste management decision-making is undertaken. • Enhanced public engagement is explored as a means to legitimise waste decisions. • Analytical–deliberative processes are explored as a tool for effective dialogue. • Considerations for integrating public values with technical analysis are outlined. • Insights into the design of appropriate public engagement processes are provided. - Abstract: The complexity of municipal waste management decision-making has increased in recent years, accompanied by growing scrutiny from stakeholders, including local communities. This complexity reflects a socio-technical framing of the risks and social impacts associated with selecting technologies and sites for waste treatment and disposal facilities. Consequently there is growing pressure on local authorities for stakeholders (including communities) to be given an early opportunity to shape local waste policy in order to encourage swift planning, development and acceptance of the technologies needed to meet statutory targets to divert waste from landfill. This paper presents findings from a research project that explored the use of analytical–deliberative processes as a legitimising tool for waste management decision-making. Adopting a mixed methods approach, the study revealed that communicating the practical benefits of more inclusive forms of engagement is proving difficult even though planning and policy delays are hindering development and implementation of waste management infrastructure. Adopting analytical–deliberative processes at a more strategic level will require local authorities and practitioners to demonstrate how expert-citizen deliberations may foster progress in resolving controversial issues, through change in individuals, communities and institutions. The findings suggest that a significant shift in culture will be necessary for local authorities to realise the potential of more inclusive decision processes. This calls for political actors and civic society to collaborate in institutionalising public involvement in both strategic and local planning structures.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Proposal of an environmental performance index to assess solid waste treatment technologies

Highlights: Black-Right-Pointing-Pointer Proposal of a new concept in waste management: Cleaner Treatment. Black-Right-Pointing-Pointer Development of an index to assess quantitatively waste treatment technologies. Black-Right-Pointing-Pointer Delphi Method was carried out so as to define environmental indicators. Black-Right-Pointing-Pointer Environmental performance evaluation of waste-to-energy plants. - Abstract: Although the concern with sustainable development and environment protection has considerably grown in the last years it is noted that the majority of decision making models and tools are still either excessively tied to economic aspects or geared to the production process. Moreover, existing models focus on the priority steps of solid waste management, beyond waste energy recovery and disposal. So, in order to help the lack of models and tools aiming at the waste treatment and final disposal, a new concept is proposed: the Cleaner Treatment, which is based on the Cleaner Production principles. This paper focuses on the development and validation of the Cleaner Treatment Index (CTI), to assess environmental performance of waste treatment technologies based on the Cleaner Treatment concept. The index is formed by aggregation (summation or product) of several indicators that consists in operational parameters. The weights of the indicator were established by Delphi Method and Brazilian Environmental Laws. In addition, sensitivity analyses were carried out comparing both aggregation methods. Finally, index validation was carried out by applying the CTI to 10 waste-to-energy plants data. From sensitivity analysis and validation results it is possible to infer that summation model is the most suitable aggregation method. For summation method, CTI results were superior to 0.5 (in a scale from 0 to 1) for most facilities evaluated. So, this study demonstrates that CTI is a simple and robust tool to assess and compare the environmental performance of different treatment plants being an excellent quantitative tool to support Cleaner Treatment implementation.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Spectroscopic identification of Ca-bearing uranyl silicates formed in C–S–H systems

Portland cement-based grouts used for radioactive waste immobilisation contain a Ca- and Si-rich binder phase, known as calcium–silicate–hydrate (C–S–H). Depending on the blend of cement used, the Ca/Si ratio can vary considerably. A range of C–S–H minerals with Ca/Si ratios from 0.6 to 1.6 were synthesised and contacted with aqueous U(VI) at 0.5 mM and 10 mM concentrations. Solid-state 29 Si MAS-NMR spectroscopy was applied to probe the Si coordination environment in U(VI)-contacted C–S–H minerals and, in conjunction with U L III -edge X-ray absorption spectroscopy analysis, inferences of the fate of U(VI) in these systems were made. At moderate or high Ca/Si ratios, uranophane-type uranyl silicates or Ca-uranates dominated, while at the lowest Ca/Si ratios, the formation of a Ca-bearing uranyl silicate mineral, similar to haiweeite (Ca[(UO 2 ) 2 Si 5 O 12 (OH) 2 ]·3H 2 O) or Ca-bearing weeksite (Ca 2 (UO 2 ) 2 Si 6 O 15 ·10H 2 O) was identified. This study highlights the influence of Ca/Si ratio on uranyl sequestration, of interest in the development of post-closure safety models for U-bearing radioactive waste disposal.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Combustion Synthesis of Transuranic-doped Ceramics for Nuclear Waste Immobilization

Utilizing the devised SCS technique, crystalline transuranic-doped zirconate pyrochlores were formed for the first time without the need for a subsequent heating step. Typically, materials rapidly synthesized in a single-step self-sustaining exothermic reaction require further heating to induce crystallization and purify the product. The need for this secondary processing step can be attributed to factors such as an improper oxidizer to fuel ratio and the utilization of strong complexing compounds as fuels (i.e., reducing agents), all of which hinder complete combustion. The efficacy of the developed process was demonstrated by fabricating crystalline plutonium-doped Gd2Zr2O7 from solutions containing metal nitrates and urea in a properly tuned ratio

Burton-Allen, Janiya D.↗
DOE OSTI2011

International Low Level Waste Disposal Practices and Facilities

The safe management of nuclear waste arising from nuclear activities is an issue of great importance for the protection of human health and the environment now and in the future. The primary goal of this report is to identify the current situation and practices being utilized across the globe to manage and store low and intermediate level radioactive waste. The countries included in this report were selected based on their nuclear power capabilities and involvement in the nuclear fuel cycle. This report highlights the nuclear waste management laws and regulations, current disposal practices, and future plans for facilities of the selected international nuclear countries. For each country presented, background information and the history of nuclear facilities are also summarized to frame the country's nuclear activities and set stage for the management practices employed. The production of nuclear energy, including all the steps in the nuclear fuel cycle, results in the generation of radioactive waste. However, radioactive waste may also be generated by other activities such as medical, laboratory, research institution, or industrial use of radioisotopes and sealed radiation sources, defense and weapons programs, and processing (mostly large scale) of mineral ores or other materials containing naturally occurring radionuclides. Radioactive waste also arises from intervention activities, which are necessary after accidents or to remediate areas affected by past practices. The radioactive waste generated arises in a wide range of physical, chemical, and radiological forms. It may be solid, liquid, or gaseous. Levels of activity concentration can vary from extremely high, such as levels associated with spent fuel and residues from fuel reprocessing, to very low, for instance those associated with radioisotope applications. Equally broad is the spectrum of half-lives of the radionuclides contained in the waste. These differences result in an equally wide variety of options for the management of radioactive waste. There is a variety of alternatives for processing waste and for short term or long term storage prior to disposal. Likewise, there are various alternatives currently in use across the globe for the safe disposal of waste, ranging from near surface to geological disposal, depending on the specific classification of the waste. At present, there appears to be a clear and unequivocal understanding that each country is ethically and legally responsible for its own wastes, in accordance with the provisions of the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management. Therefore the default position is that all nuclear wastes will be disposed of in each of the 40 or so countries concerned with nuclear power generation or part of the fuel cycle. To illustrate the global distribution of radioactive waste now and in the near future, Table 1 provides the regional breakdown, based on the UN classification of the world in regions illustrated in Figure 1, of nuclear power reactors in operation and under construction worldwide. In summary, 31 countries operate 433 plants, with a total capacity of more than 365 gigawatts of electrical energy (GW[e]). A further 65 units, totaling nearly 63 GW(e), are under construction across 15 of these nations. In addition, 65 countries are expressing new interest in, considering, or actively planning for nuclear power to help address growing energy demands to fuel economic growth and development, climate change concerns, and volatile fossil fuel prices. Of these 65 new countries, 21 are in Asia and the Pacific region, 21 are from the Africa region, 12 are in Europe (mostly Eastern Europe), and 11 in Central and South America. However, 31 of these 65 are not currently planning to build reactors, and 17 of those 31 have grids of less than 5 GW, which is said to be too small to accommodate most of the reactor designs available. For the remaining 34 countries actively planning reactors, as of September 2010: 14 indicate a strong intention to precede with introduction of nuclear power; 7 are preparing but haven't made a final decision, 10 have made a decision and are preparing infrastructure, 2 have ordered a new nuclear power plant, and 1 has a plant under construction. In all countries interested in pursuing nuclear power, it is necessary for the governments to create an environment for investment and advancement of nuclear power, including development of a professional and independent regulatory framework and regime, knowledge and refinement of skills in nuclear safety and control, definition of policies on nuclear waste management and decommissioning, and participation in international non-proliferation measures. Specifically related to radioactive waste management, nuclear facilities and industries that utilize radioactive material work to well-established safety standards for the management of their waste.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Methods and systems for capturing and storing carbon dioxide

Methods and systems for capturing and storing carbon dioxide are disclosed. In some embodiments, the methods include the following: mixing materials including magnesium or calcium with one or more acids and chelating agents to form a magnesium or calcium-rich solvent; using the organic acids derived from biogenic wastes as acids or chelating agents; generating carbonate ions by reacting a gas including carbon dioxide with a carbonic anhydrase biocatalyst; reacting the solvent with the carbonate ions to form magnesium or calcium carbonates; recycling a solution containing the biocatalyst after forming magnesium or calcium carbonates for re-use in the generating step; using the magnesium and calcium carbonates as carbon neutral filler materials and using the silica product as green filler materials or inexpensive absorbents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Innovative Process for Comprehensive Treatment of Liquid Radioactive Waste - 12551

This paper presents the results of research activities aimed at creation of a principally new LRW distilling treatment method. The new process is based on the instantaneous evaporation method widely used in distillation units. The main difference of the proposed process is that the vapor condensation is conducted without using heat exchangers in practically ideal mode by way of direct contacting in a vapor-liquid system. This process is conducted in a specially designed ejector unit in supersonic mode. Further recuperation of excess heat of vaporization is carried out in a standard heat exchanger. Such an arrangement of the process, together with use of the barometric height principle, allows to carry out LRW evaporation under low temperatures, which enables to use excess heat from NPS for heating initial LRW. Thermal calculations and model experiments have revealed that, in this case, the expenditure of energy for LRW treatment by distilling will not exceed 3 kilowatt-hour/m{sup 3}, which is comparable with the reverse-osmosis desalination method. Besides, the proposed devices are 4 to 5 times less metal-intensive than standard evaporation units. These devices are also characterized by versatility. Experiments have revealed that the new method can be used for evaporation of practically any types of LRW, including those containing a considerable amount of oil products. Owing to arrangement of the evaporation process at low temperatures, the new devices are not sensitive to 'scale formation'. This is why, they can be used for concentrating brines of up to 500-600 g/l. New types of such evaporating devices can be required both for LRW treatment processes at nuclear-power plants under design and for treating 'non-standard' LRW with complex physicochemical and radionuclide composition resulting from the disaster at the Fukushima I Nuclear Power Plant.) As a result of accidents at nuclear energy objects, as it has recently happened at NPP 'Fukushima-1', personnel faces the necessity to take emergency measures and to use marine water for cooling of reactor zone in contravention of the technological regulations. In these cases significant amount of liquid radioactive wastes of complex physicochemical composition is being generated, the purification of which by traditional methods is close to impossible. According to the practice of elimination of the accident after-effects at NPP 'Fukushima' there are still no technical means for the efficient purification of liquid radioactive wastes of complex composition like marine water from radionuclides. Therefore development of state-of-the-art highly efficient facilities capable of fast and safe purification of big amounts of liquid radioactive wastes of complex physicochemical composition from radionuclides turns to be utterly topical problem. Cesium radionuclides, being extremely dangerous for the environment, present over 90% of total radioactivity contained in liquid radioactive wastes left as a result of accidents at nuclear power objects. For the purpose of radiation accidents aftereffects liquidation VNIIHT proposes to create a plant for LRW reprocessing, consisting of 4 major technological modules: Module of LRW pretreatment to remove mechanical and organic impurities including oil products; Module of sorption purification of LWR by means of selective inorganic sorbents; Module of reverse osmotic purification and desalination; Module of deep evaporation of LRW concentrates. The first free modules are based on completed technological and designing concepts implemented by VNIIHT in the framework of LLRW Project in the period of 2000-2001 in Russia for comprehensive treatment of LWR of atomic fleet. These industrial plants proved to be highly efficient and secure during their long operation life. Module of deep evaporation is a new technological development. It will ensure conduction of evaporation and purification of LRW of different physicochemical composition, including those containing hardness salts, resulted in generation of LRW concentrate 300-600 g/l. The method is based on utilization of supersonic ejector for intensification of thermal physic processes and performance of evaporation in brine recycling mode. All proposed technological solutions are totally based on patented Russian developments. Proposed work will allow to construct modular plants, which will be totally prepared for efficient purification of any types of liquid radioactive wastes from radionuclides in case of force majeure. According to proposed scheme concentration level of cesium radionuclides in safe-for-storage form will make up not less than 5000. With respect to purification from cesium radionuclides of liquid radioactive wastes stored at NPP 'Fukushima' about 10 t of inorganic sorbents, loaded in 160 protective filter-containers, will be required for solving this problem. The amount of secondary wastes will be reduced approximately in 5 times in comparison with traditional schemes, applied in purification of secondary LRW of Fukushima-1 by Areva (France) and Kurion (USA) companies. All units of modular plants will be constructed and manufactured as totally automated, providing their twenty-four-hour safe operation. Modular design will ensure efficiency and let optimize the costs of secondary LRW treatment. In order to ensure off-line operation in emergency conditions the plant should be equipped with auxiliary modules: energy and ventilation ones. Under normal conditions these modules can be stored in 'mothballed' condition at special warehouses under the authority of federal bodies. It will be reasonable to choose required transport facilities, the most suitable for transportation of modules to target destination beforehand, using vessel classification list.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Energy Conversion Loop: Process Heat Applications of Hybrid Energy Systems

Climate change due to greenhouse gas (GHG) emissions has prompted a shift from fossil fuel energy to other sources for electricity production such as nuclear, solar or wind. These alternatives since no GHG is produced, and no fossil fuels are burned. Both nuclear and other renewable energy sources are recognized as reliable technologies in the United States and around the world. However, they all have a unique set of challenges. Two of the most common renewable energy sources are solar and wind. A particular shortcoming of these two options is the variability of the energy produced; that is they are highly dependent on weather. Many times wind and/or solar power systems are not able to meet the electric demand during peak times. Replacing fossil fuels with nuclear energy is an option (non fossil fuel) for clean energy production. Two primary challenges with using nuclear energy are; wasted heat energy and the lack of load following capabilities. First, heat energy is wasted in the production stream from steam that is created while cooling the core of a nuclear reactor. This steam is initially used in turbines where the electricity is produced. However, once the steam passes through the turbines it is cooled, re-condensed to water, and reused. Large amounts of heat energy are released in the form of heat to the environment (either to the atmosphere or as waste water) and go unused. Secondly, nuclear energy is primarily a baseload power producer - the power output does not fluctuate with power demands, or is not load following. A nuclear hybrid energy system (NHES) may be a solution to the two issues mentions above. Traditional hybrid energy systems (HES) are a combination of two or more energy producers working together to create different energy commodities such as fuel or electricity. To create a NHES, normal use of the reactor for electricity production is combined with renewable power sources to meet the peak power demand of the grid. When electricity demand is high the renewable source and NPP are used in conjunction to meet the demand. When the electricity demand is low the renewable power is used to produce electricity while the NPP operates at full capacity. Rather than sending the excess heat to the cooling towers the excess energy created by the NPP (heat) is diverted to another industrial process.There is no need to decrease the power coming out of the NPP. This research proposal addresses harvesting unused thermal energy from a NPP during normal operations and in times of low power demand.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2015

Chemical Disposition of Plutonium in Hanford Site Tank Wastes

This report examines the chemical disposition of plutonium (Pu) in Hanford Site tank wastes, by itself and in its observed and potential interactions with the neutron absorbers aluminum (Al), cadmium (Cd), chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni), and sodium (Na). Consideration also is given to the interactions of plutonium with uranium (U). No consideration of the disposition of uranium itself as an element with fissile isotopes is considered except tangentially with respect to its interaction as an absorber for plutonium. The report begins with a brief review of Hanford Site plutonium processes, examining the various means used to recover plutonium from irradiated fuel and from scrap, and also examines the intermediate processing of plutonium to prepare useful chemical forms. The paper provides an overview of Hanford tank defined-waste–type compositions and some calculations of the ratios of plutonium to absorber elements in these waste types and in individual waste analyses. These assessments are based on Hanford tank waste inventory data derived from separately published, expert assessments of tank disposal records, process flowsheets, and chemical/radiochemical analyses. This work also investigates the distribution and expected speciation of plutonium in tank waste solution and solid phases. For the solid phases, both pure plutonium compounds and plutonium interactions with absorber elements are considered. These assessments of plutonium chemistry are based largely on analyses of idealized or simulated tank waste or strongly alkaline systems. The very limited information available on plutonium behavior, disposition, and speciation in genuine tank waste also is discussed. The assessments show that plutonium coprecipitates strongly with chromium, iron, manganese and uranium absorbers. Plutonium’s chemical interactions with aluminum, nickel, and sodium are minimal to non-existent. Credit for neutronic interaction of plutonium with these absorbers occurs only if they are physically proximal in solution or the plutonium present in the solid phase is intimately mixed with compounds or solutions of these absorbers. No information on the potential chemical interaction of plutonium with cadmium was found in the technical literature. Definitive evidence of sorption or adsorption of plutonium onto various solid phases from strongly alkaline media is less clear-cut, perhaps owing to fewer studies and to some well-attributed tests run under conditions exceeding the very low solubility of plutonium. The several studies that are well-founded show that only about half of the plutonium is adsorbed from waste solutions onto sludge solid phases. The organic complexants found in many Hanford tank waste solutions seem to decrease plutonium uptake onto solids. A number of studies show plutonium sorbs effectively onto sodium titanate. Finally, this report presents findings describing the behavior of plutonium vis-à-vis other elements during sludge dissolution in nitric acid based on Hanford tank waste experience gained by lab-scale tests, chemical and radiochemical sample characterization, and full-scale processing in preparation for strontium-90 recovery from PUREX sludges.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Crystal structures of a dodecameric multicopper oxidase from Marinithermus hydrothermalis

We report multicopper oxidases (MCOs) represent a diverse family of enzymes that catalyze the oxidation of either an organic or a metal substrate with concomitant reduction of dioxygen to water. These enzymes contain variable numbers of cupredoxin domains, two, three or six per subunit, and rely on four copper ions, a single type I copper and three additional copper ions organized in a trinuclear cluster (TNC), with one type II and two type III copper ions, to catalyze the reaction. Here, two crystal structures and the enzymatic characterization of Marinithermus hydrothermalis MCO, a two-domain enzyme, are reported. This enzyme decolorizes Congo Red dye at 70°C in the presence of high halide concentrations and may therefore be useful in the detoxification of industrial waste that contains dyes. In two distinct crystal structures, MhMCO forms the trimers seen in other two-domain MCOs, but differs from these enzymes in that four trimers interact to create a dodecamer. This dodecamer of MhMCO forms a closed ball-like structure and has implications for the sequestration of bound divalent metal ions as well as substrate accessibility. In each subunit of the dodecameric structures, a Trp residue, Trp351, located between the type I and TNC sites exists in two distinct conformations, consistent with a potential role in facilitating electron transfer in the enzyme.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1976

The dilemma of future electric power demand

Dim prospects are held out for continued exponential growth rates in the generation and use of electric power worldwide and in many local areas, extrapolating from current trends and common projections. While acknowledging the unique advantages of electric power use, the article points out the 30% level of efficiency in conversion of other forms of energy to electrical energy, with huge volumes of wasted energy plus thermal pollution. Even growth at a fixed rate is found problematical, with future needs exhausting water and land resources and fossil fuels in time. Alleviation of the situation by shifting much of the load to still unproven technologies is considered cautiously

Wu, Y.-C.↗
DOE OSTI2016

Shipping Grossly Dewatered resins in the RT-100 Type B Transportation Cask - 16068

Ion-exchange resins are used in the purification of coolant water in boiling water reactor nuclear power plants. The spent resins are a form of low-level or intermediate-level radioactive waste. These resins may have a relatively high specific activity level and are normally transported to a disposal facility within a secondary container placed in a Type B transportation cask. During transportation, hydrogen gas may build up in the cask due to radiolysis of the hydrogenous material in the contents. In the licensing process, a Type B cask is carefully analyzed to ensure that the maximum amount of hydrogen gas generated does not exceed 5%. The calculation to determine the mole fraction of hydrogen gas generated is a function of many variables, including the properties of the contents and the volume ratios of the contents. Because water generates hydrogen gas when it undergoes radiolysis, the amount of water present in the waste is normally limited. Typically, Type B transportation casks are allowed to carry dewatered resins, meaning less than 1% free-standing water by volume. To ensure compliance with this limitation, the dewatering process requires specialized equipment to pump the water from the secondary container. In an effort to enhance the usability of the RT-100 Type B transportation cask, Robatel Technologies re-analyzed the hydrogen gas generation calculation for contents including 'grossly dewatered' resins. Grossly dewatered resins are defined as resins containing less than 20% free-standing water by volume. This higher limit is made possible by a more thorough hydrogen gas generation calculation, which ensures that the flammability limit is not reached during shipment. In July 2015, The USNRC issued Revision 1 of the Certificate of Compliance for the Robatel Technologies RT-100 Type B transportation cask. This revision allows the cask to be used for grossly dewatered resins. With the revised Certificate of Compliance, the RT-100 is the first of its kind whose authorized contents include greater than 1% free liquids by volume. As a result of this change, the cask user can meet the 20% maximum free-standing water volume with a much simpler gravity-driven dewatering process. It is no longer necessary to have a complex dewatering system to ensure compliance with regulatory requirements. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Exploring the speciation of actinide salts in the presence of contaminants related to molten salt reactors

Molten salt reactors (MSR) are up-and-coming Generation IV nuclear reactors with either coolant and/or radioactive fuel in molten salt form. Due to their improved safety, efficiency, affordability and convenient waste processing system, these reactors are considered a superior alternative to conventional ones. However, prior to commercial implementation, it is necessary to have an extensive understanding of the reactions occurring in the MSR. The safety parameters of the MSR are determined by the rheological properties such as density and viscosity of the molten salt and these properties are governed by the local structure of the molten salts. Due to the high operational temperatures of MSR's, corrosion plays an important role. Because of their influence, the container corrosion products become part of the fuel salt matrix. In this work, we are investigating how these corrosion products, e.g., Mo, Ni, Cr, would impact the speciation of the actinide metal centers. For the initial studies, lanthanides are used as a surrogate for actinides. Lanthanide chloride salts (LnCl3) are mixed with transition metals and excess of alkali or alkali earth metal salts or salt mixtures (LiCl, NaCl, KCl). These are added to an alumina crucible, placed in a quartz tube, and sealed under a vacuum. This is heated up to around 1000 °C and slowly cooled to a temperature above the melting point of the salt and at that temperature, the reaction is taken out of the furnace. The excess salt is removed, and the resulting product is analyzed using X-ray diffraction techniques, scanning electron microscopy, and spectroscopic methods such as Raman, UV-Visible, and FTIR spectroscopy.

37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗
NASA NTRS2005

Documentation: No Substitute for Communication

SO WHAT IS AN RFI? IT WAS ONE OF THE FIRST THINGS I learned about back when I started my project management career with my first large construction firm. I learned how to use these forms as a convenient and effective means of documenting the many legitimate clarifications needed on a major project. However, like most other young engineers, I also learned to use the RFI as a weapon in the ongoing battle between owners. or their designer and the construction contractors. Recently, our project team has done a few simple things to greatly reduce the waste and frustration that comes from this type of battle. The RFI form can be a great tool if used properly, and I certainly don t recommend that they be eliminated entirely. The RFI form was created to document the many clarifications that are commonly required on projects. Typically, the contractor uses the top half of the form to clarify-or request permission to vary from-the contract documents. The bottom half of the form is used to record the answer. But this seemingly simple process is plagued by a number of problems. From the contractor s perspective, RFIs are needed to secure information that should have been in the contract documents in the first place. The missing information keeps their crews from working effectively, and it makes hitting already demanding cost and schedule targets even more difficult. Owners, or their design firms, often view the RFI as a means of harassment. Both sides of the issue have legitimate complaints, and both sides cause most of their own pain.

Strickland, John↗