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All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

The diverse applications of plasma

Plasma being the fourth state of matter has always been an attraction for Physicists and Chemists. With the advent of time, plasma energy has been recognized in having widening horizons in the field of Biomedical Sciences. Plasma medicine can be subdivided into three main fields; Non-thermal atmospheric-pressure direct plasma for medical therapy; Plasma-assisted modification of bio-relevant surfaces and Plasma-based bio-decontamination and sterilization. The basis of the research is that as it has free carrier molecules, it has the ability to target specific cells and regulate functions like wound healing. Plasma does not harm healthy human cells but can kill bacteria and possibly even cancer cells to help treat various diseases. Nosocomial infection control, prevention and containment of contagious diseases, disinfection of medical devices, surface treatment (heat and UV sensitive surfaces) are research of interest. Recent success in generating plasma at very low temperature ie. Cold plasma makes the therapy painless. It has the ability to activate cellular responses and important mechanisms in the body. They target specific molecules such as prothrombin for blood coagulation, cytokines for killing bacteria, and angiogenesis for tissue regeneration. Plasma has bactericidal, fungicidal and virucidal properties. Plasma technology has flourishing future in diverse fields like Textiles, Nanofabrication, Automotives, Waste management, Microbiology, Food Hygiene, Medical Science like Skin treatments, sterilisation of wounds, Hand disinfection, Dental treatments etc. Food hygiene using plasma can be achieved in disinfection of food containers, food surface disinfection, hygiene in food handling, preparation and packaging. Therefore Plasma is most promising field for budding Scientist for fluorishing research in Biological Sciences.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1976

Space disposal of nuclear wastes. Volume 1: Socio-political aspects

The history and interpretation of radioactive waste management in the U.S., criteria for choosing from various options for waste disposal, and the impact of nuclear power growth from 1975 to 2000 are discussed. Preconditions for the existence of high level wastes in a form suitable for space disposal are explored. The role of the NASA space shuttle program in the space disposal of nuclear wastes, and the impact on program management, resources and regulation are examined.

Laporte, T.↗
DOE OSTI2017

An optimization model for collection, haul, transfer, treatment and disposal of infectious medical waste: Application to a Greek region

Highlights: • We developed an optimization model to minimize cost of infectious waste management. •Two different software were used for model solution. • Model optimizes locations and capacities of treatment plants and transfer stations. • The higher percentage of total cost was due to construction of the treatment plant. • Sensitivity analysis with respect to fuel cost and waste production was conducted. - Abstract: The objective of this work was to develop an optimization model to minimize the cost of a collection, haul, transfer, treatment and disposal system for infectious medical waste (IMW). The model calculates the optimum locations of the treatment facilities and transfer stations, their design capacities (t/d), the number and capacities of all waste collection, transport and transfer vehicles and their optimum transport path and the minimum IMW management system cost. Waste production nodes (hospitals, healthcare centers, peripheral health offices, private clinics and physicians in private practice) and their IMW production rates were specified and used as model inputs. The candidate locations of the treatment facilities, transfer stations and sanitary landfills were designated, using a GIS-based methodology. Specifically, Mapinfo software with exclusion criteria for non-appropriate areas was used for siting candidate locations for the construction of the treatment plant and calculating the distance and travel time of all possible vehicle routes. The objective function was a non-linear equation, which minimized the total collection, transport, treatment and disposal cost. Total cost comprised capital and operation costs for: (1) treatment plant, (2) waste transfer stations, (3) waste transport and transfer vehicles and (4) waste collection bins and hospital boxes. Binary variables were used to decide whether a treatment plant and/or a transfer station should be constructed and whether a collection route between two or more nodes should be followed. Microsoft excel software was used as installation platform of the optimization model. For the execution of the optimization routine, two completely different software were used and the results were compared, thus, resulting in higher reliability and validity of the results. The first software was Evolver, which is based on the use of genetic algorithms. The second one was Crystal Ball, which is based on Monte Carlo simulation. The model was applied to the Region of East Macedonia – Thrace in Greece. The optimum solution resulted in one treatment plant located in the sanitary landfill area of Chrysoupolis, required no transfer stations and had a total management cost of 38,800 €/month or 809 €/t. If a treatment plant is sited in the most eastern part of the Region, i.e., the industrial area of Alexandroupolis, the optimum solution would result in a transfer station of 23 m{sup 3}, located near Kavala General Hospital, and a total cost of 39,800 €/month or 831 €/t. A sensitivity analysis was conducted and two alternative scenarios were optimized. In the first scenario, a 15% rise in fuel cost and in the second scenario a 25% rise in IMW production were considered. At the end, a cost calculation in €/t/km for every type of vehicle used for haul and transfer was conducted. Also, the cost of the whole system was itemized and calculated in €/t/km and €/t. The results showed that the higher percentage of the total cost was due to the construction of the treatment plant.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Lessons Learned From the Cesium Pond Soil Shipping Campaign at Whiteshell Laboratories - 18206

Whiteshell Laboratories (WL), located in Manitoba, Canada is the first major decommissioning project of a nuclear research establishment in Canada. With the focus now active remediation to return the site to green state, the majority of legacy radioactive waste and waste generated from decommissioning and demolition of nuclear facilities must be transported off site to Chalk River Laboratories (CRL), located in Ontario, Canada. No large radioactive waste shipment campaigns have been undertaken by WL until now. A newly established Waste Management Program specifically designed to support the WL Closure Project has executed its first major shipping campaign of radioactive material, making approximately one hundred shipments and reducing WL's total volume of low-level radioactive waste to transport by seven percent. The shipped waste was approximately 1800 m{sup 3} (2600 metric tons) of known Cs-137 contaminated soil material generated from the excavation of an Experimental Cesium Pond Project designed to study the distribution of dose received by organisms living at the mud-water interface from Cs-137 contamination. This paper outlines the cost benefit analysis undertaken to determine the most cost effective method for transporting the radioactively contaminated soil to CRL, storage challenges experienced by both WL and CRL, the selection of the most appropriate waste package, training of shippers, and the continual optimization of increasing the number of generated waste packages and the number of waste packages shipped and accepted at CRL. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Nuclear criticality safety in the United Kingdom - Work In progress

Full text of publication follows: This commentary presents a brief overview of the recent and future challenges and opportunities presented by the UK nuclear industry. To give just a pure overview would lead perhaps to a rather dry and superficial review, so I have mixed in with this my own thoughts and coloured it with some of my opinions and observations from involvement in the field of Nuclear Criticality Safety (NCS) over the last 26 years. A brief overview of industry status and developments in the UK will, however, be highlighted, in order to give a background to what I hope would be an interesting personal commentary on the subject. The creation of the Nuclear Decommissioning Authority (NDA) in 2004 have (on behalf of the UK governments Department for Energy and Climate Change (DECC)) pursued the mission to 'deliver safe and sustainable solutions to the challenge of nuclear clean-up and waste management'. NDA have responsibilities for 17 of the civil nuclear facilities in the UK. This has meant for the UK nuclear industry, and in turn UK Criticality Safety, the significant focus toward safe, efficient and effective clean-up. With this mission, integrated with the ongoing commercial ventures at many of the UK licensed sites, a great variety of challenges are presented. For non-commercial activities, criticality safety has and will continue to have a significant future part to play. The UK government's commitment to a continued nuclear defense capacity ensures a major investment in the future and will continue to demand significant capability from criticality safety to support the existing commitments and future needs. Meeting these challenges demands a holistic approach to criticality safety if it is to succeed in supporting the continued safety of the industry. Technical solutions to the challenges are only part of the solution. Maintaining a technical competency, working as part of an integrated team with other safety disciplines, along with the design teams and operations management etc. are other important aspects. Working collaboratively within these teams and beyond, both nationally and internationally, is a necessary part of achieving success. Nuclear criticality safety as a discipline in the UK has always been conscious of isolation and stagnation in development given the relatively small number of personnel in the criticality field. With this concern, it benefits immensely from national and international collaboration, and this must be encouraged to continue. (author)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2018

Brexit, Euratom and Nuclear Liabilities - 18643

The outcome of the UK referendum on withdrawal from the European Union has resulted in a UK government decision that the UK must withdraw from Euratom. As at the date of the Waste Management Symposia, half of the 2-year programme for agreeing the terms of exit and putting in place replacement arrangements will have passed. If no agreement is reached by 29 March 2019 and no extension of that deadline is agreed the UK will automatically exit Euratom on that date. Aside from potential trade tariffs, Euratom exit will create binary questions on acceptability of nuclear trade and collaboration with the UK, reflecting current reliance on the UK's status as a Euratom member in establishing and implementing acceptable safeguarding requirements, ensuring inclusion of the UK within the scope of existing Euratom nuclear cooperation agreements, and as a basis for current UK bilateral nuclear cooperation agreements. This in turn risks disruption of international nuclear cooperation and trade, including provision of resources and know-how in support of the UK waste and decommissioning effort and international movement of waste for treatment. The paper will consider the current status of negotiations for UK withdrawal from Euratom, development of replacement safeguarding arrangements and replacement of international nuclear cooperation agreements essential to future nuclear cooperation and trade with the UK, taking into account: - the current and future legal basis of UK safeguarding obligations, including potential changes to the UK's Voluntary Offer Safeguards Agreement under the Non-Proliferation Treaty and likely acceptability of replacement arrangements to key nuclear trading partners; - practical arrangements for meeting those obligations post Euratom reliance via independent safeguarding arrangements; and - the need for and challenges in replacement of the UK's current reliance on its status as a Euratom member in taking the benefit of the existing US / Euratom s123 Agreement and other Euratom nuclear cooperation agreements. The paper will also provide a brief update on recent developments in international nuclear liabilities. The last 2 years have seen significant changes, with the Convention on Supplementary Compensation finally entering into force on 15 April 2015 and significant progress towards ratification of the 2004 Protocols to the Paris and Brussels Conventions. These changes are to be welcomed as beneficial to international cooperation, but also bring changes to liabilities risks associated with international movement of nuclear materials. Despite clear advances nuclear liabilities risks remain a significant consideration in negotiation of international nuclear contracts, recognising beneficial changes as well as on-going areas of risk and uncertainty. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2021

E- Area Low-Level Waste Facility Multitiered Groundwater and Intruder Radionuclide Screening

Solid Waste Management (SWM) operates the E- Area Low-Level Waste Facility (ELLWF) where low level on-site and off-site solid waste streams are buried. The facility has been in operation since late 1994 and is currently projected to remain in operation until 2065. This facility can accommodate a broad range of waste forms resulting from the six different types of disposal unit (DU) options (i.e., varying degrees of engineered barriers → trenches to concrete vaults). This facility is currently operating under a Performance Assessment (PA)issued back in 2008, along with several subsequent supporting Special Analyses (SA).

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

Experience in Remote Demolition of the Activated Biological Shielding of the Multi Purpose Research Reactor (MZFR) on the German Karlsruhe Site - 12208

In 2009, WAK Decommissioning and Waste Management GmbH (WAK) became owner and operator of the waste treatment facilities of Karlsruhe Institute of Technology (KIT) as well as of the prototype reactors, the Compact Sodium-Cooled Fast Reactor (KNK) and Multi-Purpose Reactor (MZFR), both being in an advanced stage of dismantling. Together with the dismantling and decontamination activities of the former WAK reprocessing facility since 1990, the envisaged demolishing of the R and D reactor FR2 and a hot cell facility, all governmentally funded nuclear decommissioning projects on the Karlsruhe site are concentrated under the WAK management. The small space typical of prototype research reactors represented a challenge also during the last phase of activated dismantling, dismantling of the activated biological shield of the MZFR. Successful demolition of the biological shield required detailed planning and extensive testing in the years before. In view of the limited space and the ambient dose rate that was too high for manual work, it was required to find a tool carrier system to take up and control various demolition and dismantling tools in a remote manner. The strategy formulated in the concept of dismantling the biological shield by means of a modified electro-hydraulic demolition excavator in an adaptable working scaffolding turned out to be feasible. The following boundary conditions were essential: - Remote exchange of the dismantling and removal tools in smallest space. - Positioning of various supply facilities on the working platform. - Avoiding of interfering edges. - Optimization of mass flow (removal of the dismantled mass from the working area). - Maintenance in the surroundings of the dismantling area (in the controlled area). - Testing and qualification of the facilities and training of the staff. Both the dismantling technique chosen and the proceeding selected proved to be successful. Using various designs of universal cutters developed on the basis of wall saws, both the activated steel liner and the inner reinforcing layer were cut remotely in one process. This allowed for the efficient execution of the following remote concrete removal steps using mining techniques. The electro-hydraulic demolition excavator that was purchased and then modified turned out to be an ideal tool carrier system with rapid-exchange coupling. Due to the high availability, no major delays occurred. This also was a result of the consistently implemented maintenance and repair concept. With the excavator installed in a modifiable scaffolding suspended from a rotating carrier ring, all dismantling areas could be reached and treated in spite of the small space. Thanks to an optimum organization of work-flows, routine change of dismantling work, and maintenance or repair, the iterative radiological measurement campaigns could be integrated in the whole activity without the dismantling work being disturbed significantly. The ventilation system with pressure grading and pre-filtration units ensured a low contamination level in the dismantling area. It was also possible to manage the dust formed by the milling of concrete surfaces. As it was possible to further cut metal parts and crushed concrete later on, residue flows were optimized. The planned overall period for testing, dismantling the bio-shield and removing the equipment was 36 months. The final duration was 39 months. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Surface and subsurface decontamination technology

A number of proven technologies applicable to the chemical and physical decontamination of radioactive and non-radioactive contaminants within the environmental remediation and radiological waste management sectors exist. Previous work generally acknowledges that these methods have limitations such as production of large volumes of waste, destruction of the substrate, complex safety considerations [1a] and application of special precautions to meet disposal acceptance criteria [2]. A method that removes a variety of contaminants from the surface and subsurface of porous materials, with minimal contaminated waste arisings, is highly desirable. TechXtract{sup R} is a patented, sequential chemical extraction process developed to remove radionuclides, PCBs, and other hazardous organic and inorganic substances from solid materials such as concrete, brick, steel, and exotic metals [3]. The technology uses multifarious task-specific chemical formulations and engineered applications to achieve surface penetration and removal of the contaminants from the atomic voids of metals and other substrates, or the capillaries and gel pores of concretes. TechXtract{sup R} is proven to remove a variety of contaminants from various substrates, allowing free release of the substrate as waste for disposal, or re-use, whilst producing minimal secondary waste. Data from testing of TechXtract's capabilities and evidencing the technology's efficacy during site based applied research and development is presented here. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2010

HTGR Technology Family Assessment for a Range of Fuel Cycle Missions

This report examines how the HTGR technology family can provide options for the once through, modified open cycle (MOC), or full recycle fuel cycle strategies. The HTGR can serve all the fuel cycle missions that an LWR can; both are thermal reactors. Additional analyses are warranted to determine if HTGR “full recycle” service could provide improved consumption of transuranic (TRU) material than LWRs (as expected), to analyze the unique proliferation resistance issues associated with the “pebble bed” approach, and to further test and analyze methods to separate TRISO-coated fuel particles from graphite and/or to separate used HTGR fuel meat from its TRISO coating. The feasibility of these two separation issues is not in doubt, but further R&D could clarify and reduce the cost and enable options not adequately explored at present. The analyses here and the now-demonstrated higher fuel burnup tests (after the illustrative designs studied here) should enable future MOC and full recycle HTGR concepts to more rapidly consume TRU, thereby offering waste management advantages. Interest in “limited separation” or “minimum fuel treatment” separation approaches motivates study of impurity-tolerant fuel fabrication. Several issues are outside the scope of this report, including the following: thorium fuel cycles, gas-cooled fast reactors, the reliability of TRISO-coated particles (billions in a reactor), and how soon any new reactor or fuel type could be licensed and then deployed and therefore impact fuel cycle performance measures.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2011

Dynamic Simulations of Advanced Fuel Cycles

Years of performing dynamic simulations of advanced nuclear fuel cycle options provide insights into how they could work and how one might transition from the current once-through fuel cycle. This paper summarizes those insights from the context of the 2005 objectives and goals of the U.S. Advanced Fuel Cycle Initiative (AFCI). Our intent is not to compare options, assess options versus those objectives and goals, nor recommend changes to those objectives and goals. Rather, we organize what we have learned from dynamic simulations in the context of the AFCI objectives for waste management, proliferation resistance, uranium utilization, and economics. Thus, we do not merely describe “lessons learned” from dynamic simulations but attempt to answer the “so what” question by using this context. The analyses have been performed using the Verifiable Fuel Cycle Simulation of Nuclear Fuel Cycle Dynamics (VISION). We observe that the 2005 objectives and goals do not address many of the inherently dynamic discriminators among advanced fuel cycle options and transitions thereof.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Selenite and selenate uptaken in ettringite: Immobilization mechanisms, coordination chemistry, and insights from structure

Although ettringite is a crucial material in terms of Se immobilization, the immobilization mechanisms, atomic configuration, and intercolumn structure of Se sorbed in ettringite are unclear. The immobilization mechanism of Se oxoanions was evaluated through structural insight into ettringite. It is contrasting between SeO{sub 3}{sup 2−} and SeO{sub 4}{sup 2−} in chemical property of the solid residues after immobilization. The oxoanion exchange with structural SO{sub 4}{sup 2−} is the main mechanism for immobilization of SeO{sub 4}{sup 2−}. In contrast, SeO{sub 3}{sup 2−} is easily immobilized to form inner-sphere complexes in ettringite. In addition, it is necessary to reveal the SeO{sub 3}{sup 2−} complexation sites for understanding the mechanisms in immobilization of SeO{sub 3}{sup 2−}. Based on the characterization results with the bond valence theory, the location sites of sorbed SeO{sub 3}{sup 2−} in ettringite structure were proposed. The results obtained in this work are relevant to the understanding of Se and its isotopes immobilized in cement or alkaline environments, especially for nuclear waste management. - Highlights: • The immobilization mechanisms of SeO{sub 3}{sup 2−} and SeO{sub 4}{sup 2−} in ettringite are different. • Sorption of SeO{sub 3}{sup 2−} will remove structural water molecules in ettringite. • SeO{sub 3}{sup 2−} could form some inner-sphere complexes in the ettringite structure. • The EXAFS and bond valence theory was applied to determine the sorption mechanism. • The atomic configuration of ettringite surface was proposed after sorption of SeO{sub 3}{sup 2−}.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Thermal analysis to determine acceptable package loading and spatial configurations of high-heat-generating wastes - 15411

The inventory of radioactive materials planned for geological disposal in the UK is diverse. This inventory includes a range of high-heat-generating wastes and other radioactive materials not currently declared as waste including some spent nuclear fuel and separated uranium and plutonium. To ensure that safe disposal solutions can be developed, it will be necessary to understand the influence of this heat on engineered barrier systems for the range of generic disposal concepts being considered in the UK. For these reasons, Radioactive Waste Management Limited has established a dedicated project to enhance understanding of the factors affecting geological disposal of high-heat-generating wastes with a view to supporting future decision making and concept selection. One of the priority areas to be addressed within the High-heat-generating Waste Project (Project Ankhiale) concerns the effect of heat on the engineered barrier systems. The core focus of the work is to identify the thermal constraints on specific outline conceptual designs, building upon the findings of other work activities aimed at understanding the influence of heat on buffer materials. The constraints on the design relate to important features of the engineered barrier system and parameters such as waste package loading, package dimensions and package spacing. Work is underway to identify an acceptable range of designs and parameters for waste package disposal concepts and layout of the GDF. (authors)

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

A Thermodynamic Model for Nd(III)–Sulfate Interaction at High Ionic Strengths and Elevated Temperatures: Applications to Rare Earth Element Extraction

Neodymium (Nd), a rare earth element (REE), is critical to numerous industries. Neodymium can be extracted from ore concentrates, waste materials, or recycled materials such as recycled Nd-Fe-B permanent magnets. In a standard process, concentrated sulfuric acid (H 2 SO 4 ) is used as an extraction/leaching agent. Therefore, knowledge of Nd(III)–sulfate interaction at high ionic strengths is important for optimization of the extraction process. In addition, sulfate is also a major species in natural surface waters and present in nuclear waste streams. Nd(III) has been used a chemical analog to trivalent actinides in nuclear waste research and development. Consequently, knowledge of Nd(III)-sulfate interactions is also impactful to the field of nuclear waste management. Here, in this study, we have developed a thermodynamic model that can describe the interaction of Nd(III) with sulfate to ionic strengths up to ~ 16.5 mol·kg –1 and to temperatures up to 100 °C. The model adopts the Pitzer formulation to describe activity coefficients of aqueous species. This model can be used to design and optimize a chemical process for REE recovery from ore concentrates, recycled materials, and acid mine drainage (AMD) and to understand the mobility of REEs and actinides in the environment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

From Dealing with Legacy Waste to Avoiding It - 17432

When dealing with radioactive waste management and its regulation, there are various national approaches. At the same time there is a growing tendency towards consideration of fundamental principles and standards thus forming the underlying basics in detailing the customized regulatory framework for specific applications. Dealing with legacy waste poses some particular problems as at the time of its production current safety principles were sometimes not well established. Considering today's standards this frequently requires remedial actions. Usually, this involves considerable effort and cost as well as radiation exposure for the involved personnel. Resolving legacy waste related problems not only benefits from an established regulatory framework but allows conclusions on how deal with legacy waste problems in general. The most important lessons learned from such operations might be how to prevent the production of legacy waste in the first place, thus avoiding further problems. By reflecting on practical applications from a number of countries the presentation is set to carve out the crucial recommendations from internationally recognized standards that give a substantial dividend in terms of not only time and budget but most of all safety and radiation exposure when properly implemented. The scope of the examples given ranges from dealing with legacy waste to avoiding it and includes recommendations towards essential features of best practice as seen from the perspective of an independent expert organization. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Hyperspectral imaging for real-time waste materials characterization and recovery using endmember extraction and abundance detection

Hyperspectral imaging, combined with advanced spectral unmixing techniques and artificial intelligence, offers a powerful solution for improving material identification and classification. Here, this study evaluates the effectiveness of the pixel purity index and the sequential maximum angle convex cone algorithms in extracting and validating spectral signatures from pure samples of paper components (cellulose and lignin) and plastic (polypropylene). Principal-component analysis showed that both algorithms captured nearly all relevant variance for the tested materials. Spectral signatures were compared using the spectral angle mapper, revealing high similarity in the short-wave infrared region and greater variability in the visible near-infrared range. The methodology was then applied to a disposable coffee cup to detect and quantify mixed materials, accurately estimating material abundance and object area with less than 1% error. This approach enhances material classification, supporting product verification, quality control, and automated sorting for sustainable waste management and resource recovery.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Backfilling of Geological Disposal Facilities - Development of Optimized Backfill Material - 18146

In Belgium, low- and intermediate-level waste (B-waste) will be conditioned in concrete monoliths and high-level waste (C-waste) in so-called Super-containers (SCs). The Belgian radioactive waste management program has focused on the disposal of these waste types in two emplacement fields of a geological disposal facility (GDF). When the disposal waste packages (DWP) have been emplaced, backfilling of the galleries is supposed to be carried out in order to stabilize the galleries, to reduce voids, to guarantee a favourable chemical milieu with regard to the retention of the radionuclides, to minimize a possible gas pressure build-up, to dissipate radioactive decay heat and to enable good conditions for a potential retrieval of the DWP. The current reference solution is to mix the backfill at the surface and then to pump the mixture through pipeline distribution systems into the underground structures. The catalogue of backfill material requirements comprises common, but also different requirements due to the characteristics of the B and C waste packages and differences in the backfilling systems. It was found that two backfill material recipes have to be developed. Different requirements, such as high porosity (low strength and low gas threshold pressure) and high thermal conductivity have contrary consequences for the material. In addition, during backfill production quality variations of the raw materials that influence the backfill material properties can occur. Different lengths of the delivery pipeline may require adjustments of the material composition. In order to consider the practical experiences of backfill material production, one focus of the development programs was to identify compositional ranges that guarantee the respective material property. A combination of the individual 'conformity fields' results in optimal solutions for the standard operating conditions as well as a compositional range that guarantees compliance with the required material specifications. (authors)

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

Combined Municipal Solid Waste and biomass system optimization for district energy applications

Highlights: • Combined energy conversion of MSW and agricultural residue biomass is examined. • The model optimizes the financial yield of the investment. • Several system specifications are optimally defined by the optimization model. • The application to a case study in Greece shows positive financial yield. • The investment is mostly sensitive on the interest rate, the investment cost and the heating oil price. - Abstract: Municipal Solid Waste (MSW) disposal has been a controversial issue in many countries over the past years, due to disagreement among the various stakeholders on the waste management policies and technologies to be adopted. One of the ways of treating/disposing MSW is energy recovery, as waste is considered to contain a considerable amount of bio-waste and therefore can lead to renewable energy production. The overall efficiency can be very high in the cases of co-generation or tri-generation. In this paper a model is presented, aiming to support decision makers in issues relating to Municipal Solid Waste energy recovery. The idea of using more fuel sources, including MSW and agricultural residue biomass that may exist in a rural area, is explored. The model aims at optimizing the system specifications, such as the capacity of the base-load Waste-to-Energy facility, the capacity of the peak-load biomass boiler and the location of the facility. Furthermore, it defines the quantity of each potential fuel source that should be used annually, in order to maximize the financial yield of the investment. The results of an energy tri-generation case study application at a rural area of Greece, using mixed MSW and biomass, indicate positive financial yield of investment. In addition, a sensitivity analysis is performed on the effect of the most important parameters of the model on the optimum solution, pinpointing the parameters of interest rate, investment cost and heating oil price, as those requiring the attention of the decision makers. Finally, the sensitivity analysis is enhanced by a stochastic analysis to determine the effect of the volatility of parameters on the robustness of the model and the solution obtained.

09 BIOMASS FUELS↗