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Multi-Sensor Optimal Motion Planning for Radiological Contamination Surveys by Using Prediction-Difference Maps

Distributed and networked mobile sensor platforms using unmanned aerial and/or ground vehicles to survey areas of interest offer a safer and more efficient method for radiological contamination mapping; however, most applications rely on uniformly sweeping of the area in a raster-type motion without utilizing the information available in a dynamic sense. We have developed a fully autonomous optimal motion planning procedure for networks with two or more mobile sensors. The procedure utilizes well-established concepts of Gaussian processes in combination with control laws based on centroidal Voronoi tessellations to achieve optimal next-iteration sensor movements. A new method of informing optimal motion planning is proposed, whereby the absolute difference between the prior and current full-map prediction, referred to as the prediction-difference map, is used as the spatial density function within each Voronoi cell, providing immediate and iterative feedback for dynamic use of available information. The Gaussian process regression model used to estimate the contamination in unvisited locations also provides prediction uncertainties, and can be used as a quantitative metric to assess the confidence in the calculated contamination map; these estimates and prediction uncertainties are unavailable for standard uniform survey routines as they can only produce maps in the vicinity of observed locations. We present through simulation the achievable performance gains from using this new method by directly comparing to a uniform survey method. Results show that using the prediction-difference maps to inform motion planning procedures offers a faster rate of producing an accurate and convergent map relative to a uniform survey route.

47 OTHER INSTRUMENTATION↗

Progress toward Biomass and Coal-Derived Syngas Warm Cleanup: Proof-of-Concept Process Demonstration of Multicontaminant Removal for Biomass Application

Systems comprising of multiple sorbent and catalytic beds have been developed for the warm syngas cleanup of coal- and biomass-derived syngas. Tailored specifically for biomass application the process described here consists of six primary unit operations: 1) Na2CO3 bed for HCl removal, 2) two regenerable ZnO beds for bulk H2S removal, 3) ZnO bed for H2S polishing, 4) NiCu/SBA-16 sorbent for trace metal (e.g. AsH3) removal, 5) steam reforming catalyst bed for tars and light hydrocarbons reformation and NH3 decomposition, and a 6) Cu-based LT-WGS catalyst bed. Simulated biomass-derived syngas containing a multitude of inorganic contaminants (H2S, AsH3, HCl, and NH3) and hydrocarbon additives (methane, ethylene, benzene, and naphthalene) was used to demonstrate process effectiveness. The efficiency of the process was demonstrated for a period of 175 hours, during which no signs of deactivation were observed. Post-run analysis revealed small levels of sulfur slipped through the sorbent bed train to the two downstream catalytic beds. Future improvements could be made to the trace metal polishing sorbent to ensure complete inorganic contaminant removal (to low ppb level) prior to the catalytic steps. However, dual, regenerating ZnO beds were effective for continuous removal for the vast majority of the sulfur present in the feed gas. The process was effective for complete AsH3 and HCl removal. The steam reforming catalyst completely reformed all the hydrocarbons present in the feed (methane, ethylene, benzene, and naphthalene) to additional syngas. However, post-run evaluation, under kinetically-controlled conditions, indicates deactivation of the steam reforming catalyst. Spent material characterization suggests this is attributed, in part, to coke formation, likely due to the presence of benzene and/or naphthalene in the feed. Future adaptation of this technology may require dual, regenerable steam reformers. The process and materials described in this report hold promise for a warm cleanup of a variety of contaminant species within warm syngas.

Environmental Molecular Sciences Laboratory↗

Radiological Survey and Release Report for 9404-17 & 9404-18

The data quality objective (DQO) process and a graded approach are integrated within the MARSSIM process and within the plan to assure defensible data with cost effectiveness. Surveys were performed by trained Radiological Control Technicians (RCTs) following standard, written procedures and using properly calibrated instruments, sensitive to the potential contaminants. Instrumentation identification and the name of the technicians performing the survey can be found in the referenced radiological surveys.

54 ENVIRONMENTAL SCIENCES↗

Polarization Control via He-Ion Beam Induced Nanofabrication in Layered Ferroelectric Semiconductors

Rapid advanced in nanoscience rely on continuous improvements of matter manipulation at near atomic scales. Currently, well characterized, robust, resist-based lithography carries the brunt of the nanofabrication process. However, use of local electron, ion and physical probe methods is also expanding, driven largely by their ability to fabricate without the multi-step preparation processes that can result in contamination from resists and solvents. Furthermore, probe based methods extend beyond nanofabrication to nanomanipulation and imaging, vital ingredients to rapid transition to prototyping and testing of layered 2D heterostructured devices. In this work we demonstrate that helium ion interaction, in a Helium Ion Microscope (HIM), with the surface of bulk copper indium thiophosphate CuM III P 2 X 6 (M = Cr, In; X= S, Se), (CITP) results in the control of ferroelectric domains, and growth of cylindrical nanostructures with enhanced conductivity; with material volumes scaling with the dosage of the beam. The nanostructures are oxygen rich, sulfur poor, and with the copper concentration virtually unchanged as confirmed by Energy Dispersive X-ray (EDX). Scanning Electron Microscopy (SEM) imaging contrast as well as Scanning Microwave Microscopy (SMM) measurements suggest enhanced conductivity in the formed particle, whereas Atomic Force Microscopy (AFM) measurements indicate that the produced structures have lower dissipation and a lower Young s modulus.

2D crystals↗

Gaussian process regression for radiological contamination mapping- Applied to optimal motion planning for mobile sensor platforms [Slides]

Want to achieve best representative characterization of the entire area efficiently and accurately-Unmanned aerial/ground vehicles (UAV/UGVs) for contamination mapping. Some major challenges include: Limited battery life (move smart), Human operated (fully autonomous controls) and Many measurements (predictive mapping capabilities). The objective: Develop fully autonomous controls for mobile sensor platforms to improve efficiency and maintain performance.

61 RADIATION PROTECTION AND DOSIMETRY↗

Remediation Guidance for Major Airports after a Bioterrorist Attack

This document provides general guidelines for airport managers, local officials, and other stakeholders for developing a response and recovery plan for a major airport following the release of a biological warfare agent, with specific guidance for remediation. San Francisco International Airport was selected as the example airport during development of the guidance to illustrate specific details. The spore-forming bacterium Bacillus anthracis was selected as the biological agent of primary concern because it is the most difficult of known bioterrorism agents to inactivate and is considered to be one of the agents most likely to be used as a biological weapon. The focus of the guidance is on cleanup and disposal activities associated with the Characterization, Decontamination, and Clearance Phases that are defined herein. Activities associated with the Notification and First-Response Phases are brieÀy discussed in Appendixes A and B, respectively. In addition to the main text of this Remediation Guidance document and associated appendixes, a data supplement was developed specifically for San Francisco International Airport. Requests for the data supplement must be made directly to the Emergency Planning Operations Division of San Francisco International Airport. This document does not describe public health responses to release of a biological warfare agent. If laboratory analytical results confirm the presence of a biological agent, the responsible public health agency involved in the response will commence appropriate public health actions, such as treatment (CDC 2004) and decontamination of potentially contaminated individuals, distribution of prophylaxis, and medical examinations. See the Centers for Disease Control and Prevention web site for more information on emergency public health responses (http://www.bt.cdc.gov/). Effective communication with the media and the public is an essential component of airport remediation and recovery. Whereas such communication is beyond the scope of this document, many helpful resources are available. (See Section 1.1 for more information.) The concept of operations described in this document for cleanup of a Bacillus anthracis release at a major airport conforms to the National Response Framework (NRF) (DHS 2008) and implementation of the National Incident Management System (NIMS 2004). In most cases, a Unified Command would be formed to direct the cleanup process jointly and to take ultimate responsibility for all cleanup decisions. The Unified Command would likely include the Airport Manager or Airport Emergency Operations Manager, representatives from state and local public health and emergency management agencies, and Federal agencies, such as the U.S. Environmental Protection Agency. The Unified Command and Incident Command Staff would ideally be co-located in an Incident Command Post in an uncontaminated area of the airport. If a release is large or complex, co-location of all key players may not be possible. If a major incident is declared, a Principal Federal Official may be appointed by the Department of Homeland Security to facilitate Federal support to the Unified Command. In some facilities and jurisdictions, additional response plans or procedures (such as BioWatch or other emergency response plans, procedures, or protocols) may govern notification and first response. Facility personnel, responders, and emergency management coordinators should be aware of all applicable plans and procedures and how to implement them. Cleanups following the anthrax attacks of 2001 in the U.S. pre-dated the NRF and NIMS and did not make use of a NIMS Incident Command System as we know it today. Most Incident Commanders for the larger of those cleanups chose to convene a Technical Working Group (TWG) of multi-agency, multi-disciplinary, outside experts to advise in developing sampling and decontamination plans. Most of the Incident Commanders also convened a separate Environmental Clearance Committee (ECC) to independently review pre- and post decontamination sampling data as well as data on decontamination parameters, to evaluate whether the decontamination was effective, and to add credibility regarding a decision that decontaminated areas may be reoccupied. Use of such specialized technical expertise is strongly recommended, although it would now operate within the construct of the NIMS Incident Command System. The TWG, if convened, would act in an advisory capacity to the Environmental Unit within the Planning Section. Likewise, the ECC, if convened, would provide independent peer review of products and recommendations by the Environmental Unit. For maximum impartiality, the ECC could also provide recommendations directly to the Unified Command. Cleanup activities commence with site characterization. The principal goal of characterization is to define the extent of contamination and to gather information needed to design the decontamination approach. Initial sampling data collected by first responders are assessed to approximate the location(s) of contamination. Confirmation of the agent type and viability is obtained from a Laboratory Response Network laboratory. Additional characterization data are collected to determine the extent of contamination and where decontamination actions are needed. Areas suspected of being contaminated are contained and isolated to the degree possible to prevent further movement of an agent to uncontaminated areas or the environment, and to reduce the potential for future exposure from the agent or fumigant, if fumigation is needed. Agent air monitoring in areas adjacent to the contained contamination zones is done to ensure the protection of remediation personnel and to monitor any release from the contained zones. Various sampling approaches are considered. For example, wipe samples can be used to sample hard, nonporous surfaces. Swab samples can be used to sample nooks, crannies, joints, and seams. Appendix I is a template for preparing an incident-specific, operational characterization plan. Upon completion of the characterization plan, an internal review is initiated. Upon approval of the plan by the Unified Command, characterization commences. The Site Safety Officer develops a Health and Safety Plan to ensure that coordinated health and safety measures are in place for all responding personnel. This plan describes physical, chemical, and biological hazards at the site, personal protective equipment, personal decontamination procedures, and emergency procedures to be used by sampling and remediation personnel. An incident-specific Remediation Action Plan is developed, which describes the decontamination methods to be used and other details, including waste disposal. Under NIMS, this overall plan, as well as other plans described below, are implemented through a series of standardized, shorter-term Incident Action Plans, which describe specific activities that will take place during a shift or a day. The template in Appendix J is designed to facilitate preparation of the Remediation Action Plan. If fumigation will be done, a Sampling and Analysis Plan will be needed, as well as an Ambient Air Monitoring Plan, which can be a component of the Remediation Action Plan. These three plans are needed to obtain a crisis exemption from the U.S. Environmental Protection Agency for authorized use of an unregistered sterilant or pesticide during cleanup. If pesticide products become registered for inactivation of B. anthracis in the future, the three plans will likely be required by the product’s labeling, but the plans would no longer be submitted to the U.S. Environmental Protection Agency for approval; rather, the Incident Commander would approve them. If fumigation is used, an Emergency Response Plan is also recommended, although such a plan is not required for a crisis exemption. For some nonpersistent biological warfare agents, natural attenuation may be an adequate decontamination option. In cases where contamination is not extensive or an agent is not persistent, application of surface decontaminants or other methods of medical infection control may be effective. For extensive contamination by persistent agents, such as Bacillus anthracis, fumigation may be necessary. In those cases, the Decontamination Phase commences with source reduction, such as pre-cleaning surfaces to reduce the contaminant load. To expedite cleanup and prevent costs from escalating unnecessarily, a cost–benefit analysis should be incorporated in the decision process related to retention versus disposal of facility items and materials. Certain materials and structural components can be decontaminated for reuse, but it may not be feasible or cost-effective to decontaminate other items. Those items must be pre-treated, packaged (with the package decontaminated externally), and removed for disposal as waste. Site preparation includes sealing openings to prevent leaks and setting up equipment. Decontamination reagents and delivery systems are selected, and pre-testing all systems is done before carrying out chemical treatment(s). The important choice of decontamination technologies depends on characteristics of the agent, the nature and extent of contamination, and other site parameters identified during characterization. Decontamination-related decisions can have a major impact on waste-disposal costs, and it is necessary to develop a disposal plan that identifies a means of disposal, necessary approvals, transportation, and other details. A clearance strategy is developed to ensure that after decontamination, the risk of exposure to residual contamination is negligible. A clearance sampling plan is developed, which sets clearance criteria, specifies how to determine whether the criteria have been met, and describes how and where to collect clearance samples after decontamination. In most cases, clearance sampling includes both surface and aggressive air samples. Appendix K is a clearance plan template that identifies the types of required information. To determine whether the decontaminated area may be reoccupied, the Environmental Unit (and the ECC separately, if one is convened) evaluates the results of clearance samples. For the anthrax incidents to date, and given methods that have been used, cleanup was considered successful only when there was no growth of B. anthracis cultured from any environmental samples taken after decontamination. Other factors that will be considered include the decontamination process parameters (e.g., temperature, relative humidity, decontaminant concentration, and contact time) and the results from post-decontamination culture of biological indicators that may have been used during fumigation or sterilization processes. From such an evaluation the Environmental Unit or ECC, or both, recommend whether the area may be reoccupied, or whether further decontamination is necessary. The UC makes the final decision that a facility is appropriately decontaminated for reoccupancy. The facility owner or responsible public health agency makes the final decision to reopen a decontaminated facility. A theme that is emphasized throughout this document is that many activities can greatly reduce the time required to restore airport operations if those activities are conducted prior to an actual release of biological warfare agent. A summary of specific resources (such as Federal, state, and local agency contacts; contractors; prospective team members; subject-matter experts; laboratory facilities; and other entities) that should be identified in advance by airport officials is provided in each pertinent section of this document, and summary contact lists of such resources are provided in Appendix L. A summary of overall pre-planning actions that should be completed by airport officials is presented at the end of this document.

59 BASIC BIOLOGICAL SCIENCES↗

Structural analyses of amorphous calcium carbonate before and after removing strontium ions from an aqueous solution

Amorphous calcium carbonate (ACC) is a precursor of crystalline calcium carbonate; hence, its structural information at the atomic level is very important for controlling the morphology of crystalline calcium carbonate. In this study, we attempted to elucidate the process of Sr extraction from aqueous solution by using ACC for the purpose of removal of radioactive Sr from the contaminated water leaked after the Fukushima Daiichi nuclear accident. Here, the pair distribution functions, g(r) obtained by X-ray and neutron diffraction (ND) measurements show that ACC has a structure partially similar to that of monohydrocalcite, suggesting that ACC is transferred to the crystalline calcium carbonate starting from its crystal nucleus. Rietveld analysis of the ND data showed that the ACC that removed Sr was crystallized to calcite. However, the Sr–O coordination analyzed using extended X-ray absorption fine structure (EXAFS) implies that the local environment of O around Sr is similar to that in crystalline calcium carbonate aragonite.

36 MATERIALS SCIENCE↗

Cold Testing for Characterization of Oxide Feed Impurities in Support of the ARIES Program

The Advanced Recovery and Integrated Extraction System (ARIES) Program converts surplus plutonium metal components into an oxide powder form and packages the material for final disposition. In support of the ARIES program, over a metric ton (MT) of plutonium has been removed from surplus nuclear weapons since 1998 and packaged for long-term storage in 3013 cans. The oxide production rate is anticipated to increase substantially over the next decade in support of dilute and dispose goals. Analytical chemistry data from destructive analysis of the resulting 70+ blend lots to date has been reported for contaminants in the product oxide. Changes in the Pu product specification for Pu oxide product, induced by a different pit mix, the LANL swap program and processing Alternate (non-Pit Pu) Feed Stock (AFS) metals, will affect the level and the mix of these contaminants in the upcoming years. With these changes in feed material, it will be important to provide fast and efficient measurement of elemental impurities in the oxide to be certain that the process is under control and to monitor the anticipated changes from the historical blend lot data. Non-destructive methods need to be evaluated for the characterization of the plutonium oxide product and the quantification of the impurities at the current and anticipated levels. A feasibility study has begun to investigate the applicability of new spectroscopic methods for oxide impurity characterization. To this end, here we describe the preparation of surrogate materials to support these investigations, and the results of a feasibility study investigating the use of LIBS (Laser Induced Breakdown Spectroscopy) to characterize the surrogate materials as calibration standards.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Solvent-driven aqueous separations for hypersaline brine concentration and resource recovery

Solvent-driven separation processes can extract water and high-value minerals from high salinity or contaminated brines, simultaneously reducing the environmental impact of brine disposal and enabling resource recovery. The efficient dewatering of hypersaline brines is essential for the sustainable minimal and zero liquid discharge processing of industrial wastewaters. Fractional crystallization can selectively extract ions from contaminated waste streams, allowing critical materials to be recycled, including transition and lanthanide metals required for renewable energy generation and storage. Mass transfer in solvent-driven water extraction occurs across a liquid–liquid interface, eliminating the scaling and fouling of membrane and heat exchanger surfaces and limiting the need for extensive pretreatment. Solvent-driven fractional crystallization can leverage sequential treatment and control of process conditions to rapidly recover salts without requiring evaporation of water. Despite promising applications, the principles and potential of solvent-driven aqueous separations remain poorly understood. This critical review explores the opportunities presented by solvent-based aqueous separations from the molecular to process scale, evaluating the chemistry of solvation and system design in the broader context of desalination, resource recovery, water softening, and mineral production.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

The Walls Come Tumbling Down: Decontamination and Demolition of 29 Manhattan Project and Cold War-Era Buildings and Structures at Los Alamos National Laboratory-12301

When the nation's top scientists and military leaders converged on Los Alamos, New Mexico in the 1943, to work on the Manhattan Project, the facilities they used to conduct their top-secret work were quickly constructed and located in the middle of what eventually became the Los Alamos town site. After one of these early facilities caught on fire, it seemed wise to build labs and production facilities farther away from the homes of the town's residents. They chose to build facilities on what was then known as Delta Prime (DP) Mesa and called it Technical Area 21, or TA-21. With wartime urgency, a number of buildings were built at TA-21, some in as little as a few months. Before long, DP Mesa was populated with several nondescript metal and cinder-block buildings, including what became, immediately following the war, the world's first plutonium production facility. TA-21 also housed labs that used hazardous chemicals and analyzed americium, tritium and plutonium. TA-21 was a bustling center of research and production for the next several decades. Additional buildings were built there in the 1960's, but by the 1990's many of them had reached the end of their service lives. Labs and offices were moved to newer, more modern buildings. When Los Alamos National Laboratory received $212 million in funding from the American Recovery and Reinvestment Act in July 2009 for environmental cleanup projects, about $73 million of the funds were earmarked to decontaminate and demolish 21 of the old buildings at TA-21. Although some D and D of TA-21 buildings was performed in the 1990's, many of the facilities at DP Site remained relatively untouched for nearly three decades following their final operational use. In 2006, there were over three dozen buildings or structures on the mesa to be removed so that soil cleanup could be completed (and the land made available for transfer and reuse). The total footprint of buildings across the mesa was approximately 18,580 m{sup 2} (200,000 ft{sup 2}). The initially approved baseline for the ARRA D and D Project was to remove 22 buildings and structures that included approximately 14,680 m{sup 2} (158,000 ft{sup 2}) of footprint. By employing efficiencies during subcontracting, demolition, and waste segregation, the savings allowed an additional 1,580 m{sup 2} (17,000 ft{sup 2}) of footprint to be removed using ARRA funds. Additionally, the lessons learned from this experience were used to apply NNSA funding to the removal of six additional non-contaminated buildings and structures. In the end, 29 buildings and structures, including stacks, cooling towers and tanks, were removed from the mesa. The entire DP East area was cleared of buildings and sub-grade structures and the soils cleaned to residential standards. The total footprint reduction at TA-21 as a result of this effort was in excess of 17,650 m{sup 2} (190,000 ft{sup 2}). The use of a Laboratory self-performance team to start demolition of non-contaminated structures resulted in steady work performance early in the project while subcontracts were being put in place to perform more complicated abatement and contaminated demolition activities. Most importantly, there were no serious worker injuries and the minor injuries recorded were those common to construction type activities. Extensive monitoring along the site boundary demonstrated that no hazardous chemicals or radioactive contamination were released and radiological dose to the public was negligible. The ARRA demolition activities were completed six months in advance of the deadline for employing ARRA funds. Additionally, over 17,585 m{sup 3} (23,000 yds{sup 3}) of building demolition debris was safely removed from DP Mesa. All of the major buildings have been removed, unencumbered access to the SWMUs that are required to be cleaned up by the Consent Order with the state of New Mexico, has been achieved, and a significant portion of the mesa has been prepared to support a process that will eventually transfer this land from federal government control for further use. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Environmental cleanup of the East Tennessee Technology Park - Year three - A status report - 15522

On August 1, 2011, URS - CH2M Oak Ridge LLC (UCOR) began its five-year, $1.4 billion cleanup of the East Tennessee Technology Park (ETTP), the former Oak Ridge Gaseous Diffusion Plant, located on the U.S. Department of Energy's (DOE) Oak Ridge Reservation (Reservation) in Tennessee. Under the contract, the base period scope of work to be completed by 2016 includes demolition of both the K-25 and K-31 gaseous diffusion buildings and all demolition waste dispositioned, initiation of demolition on the remaining K-27 gaseous diffusion building, safe storage of transuranic (TRU) waste for eventual transfer to the Transuranic Waste Processing Center, previously designated -No-Path-To-Disposition Waste- dispositioned to the extent possible, and completion of design and engineering of a mercury treatment system to be installed at the Y-12 National Security Complex (Y-12). UCOR will have also managed DOE Oak Ridge Office of Environmental Management (OREM)-owned facilities at ETTP, Oak Ridge National Laboratory (ORNL), and Y-12 in a safe and cost-effective manner. Since assuming responsibilities as the ETTP and Oak Ridge Reservation cleanup contractor, UCOR has completed its life-cycle Performance Measurement Baseline; received its Earned Value Management System (EVMS) certification; completed the deactivation and demolition (D and D) of the 44-acre K-25 gaseous diffusion building; removed and disposed of a contaminated underground storage tank (Tank W-1A) at ORNL; dispositioned mercury-contaminated storage tanks at Y-12; completed closure of the Toxic Substances Control Act Incinerator; disposed of more than 158,000 cubic yards of cleanup waste while managing the on-site Environmental Management Waste Management Facility (EMWMF); and conducted operations, surveillance, and maintenance activities at 180 DOE EM facilities at ETTP, ORNL, and Y-12 in a safe and cost-effective manner. In 2014, UCOR completed the removal and disposal of all of the K-25 demolition debris; completed the removal of asbestos-laden transite siding on the K-31 gaseous diffusion building and began demolition of that 17-acre building; advanced the characterization and deactivation of the K-27 gaseous diffusion building, readying the building for the start of demolition in 2015; advanced the design and engineering of a Mercury Treatment Facility to be located at Y-12; continued the cost-effective and safe disposition of all cleanup wastes; and readied ETTP for Voluntary Protection Program Star Status Assessment in 2015. Project performance as of December 31, 2014, continued to be excellent: - Cost Performance Index - 1.12 - Schedule Performance Index - 1.02 At the same time, since safety is the foundation of all cleanup work, UCOR's safety record goes hand-in-hand with its excellent project performance. Through calendar year 2014, UCOR's recordable injury rate was 1.04 occurrences per 200,000 work hours, and the lost workday case rate was 0.52. This performance continues to be due, in large part, to the people and processes URS and CH2M HILL, the parent companies of UCOR, brought to the project. Key enablers included: - Selected and deployed experienced staff in key leadership positions throughout the organization, continually re-energizing the organization with new leaders - Implemented previously successful safety programs and initiatives from other DOE sites, such as DOE's Voluntary Protection Program - Brought fresh thinking and innovation to tackling tough project issues, such as the deactivation of the Technetium-99-contaminated areas of K-27, applying lessons learned from the D and D of K-25; and implementing a -waste factory- approach to cleanup - Maintained continuing alignment between UCOR's contract with DOE and its Performance Measurement Baseline - rapidly addressing contract changes when they arose - Maintained a readiness both from a process as well as experienced personnel perspective to support DOE OREM in performing other significant Oak Ridge Reservation cleanup activities. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Innovative Use of Cr(VI) Plume Depictions and Pump-and-Treat Capture Analysis to Estimate Risks of Contaminant Discharge to Surface Water at Hanford Reactor Areas

The Hanford Site nuclear reactor operations required large quantities of high-quality cooling water, which was treated with chemicals including sodium dichromate dihydrate for corrosion control. Cooling water leakage, as well as intentional discharge of cooling water to ground during upset conditions, produced extensive groundwater recharge mounds consisting largely of contaminated cooling water and resulted in wide distribution of hexavalent chromium (Cr[VI]) contamination in the unconfined aquifer. The 2013 Cr(VI) groundwater plumes in the 100 Areas cover approximately 6 km2 (1500 acres), primarily in the 100-HR-3 and 100-KR-4 groundwater operable units (OUs). The Columbia River is a groundwater discharge boundary; where the plumes are adjacent to the Columbia River there remains a potential to discharge Cr(VI) to the river at concentrations above water quality criteria. The pump-and-treat systems along the River Corridor are operating with two main goals: 1) protection of the Columbia River, and 2) recovery of contaminant mass. An evaluation of the effectiveness of the pump-and-treat systems was needed to determine if the Columbia River was protected from contamination, and also to determine where additional system modifications may be needed. In response to this need, a technique for assessing the river protection was developed which takes into consideration seasonal migration of the plume and hydraulic performance of the operating well fields. Groundwater contaminant plume maps are generated across the Hanford Site on an annual basis. The assessment technique overlays the annual plume and the capture efficiency maps for the various pump and treat systems. The river protection analysis technique was prepared for use at the Hanford site and is described in detail in M.J. Tonkin, 2013. Interpolated capture frequency maps, based on mapping dynamic water level observed in observation wells and derived water levels in the vicinity of extraction and injection wells, are developed initially. Second, simulated capture frequency maps are developed, based on transport modelling results. Both interpolated and simulated capture frequency maps are based on operation of the systems over a full year. These two capture maps are then overlaid on the plume distribution maps for inspection of the relative orientation of the contaminant plumes with the capture frequency. To quantify the relative degree of protection of the river from discharges of Cr(VI) (and conversely, the degree of threat) at any particular location, a systematic method of evaluating and mapping the plume/capture relationship was developed. By comparing the spatial relationship between contaminant plumes and hydraulic capture frequency, an index of relative protectiveness is developed and the results posted on the combined plume/capture plan view map. Areas exhibiting lesser degrees of river protection are identified for remedial process optimization actions to control plumes and prevent continuing discharge of Cr(VI) to the river.

Miller, Chuck W.↗

Development of a Trace Detection Method for Mercury Speciation in Hanford Tank Waste - 19014

The U.S. Department of Energy's (DOE) Hanford Site in southeast Washington State stores 56 million gallons of chemical and radioactive waste stored in underground tanks. Mercury species in liquid and solid fractions of Hanford tank waste pose a risk to the implementation and execution of DoE's River Protection Project mission due to mercury concentration limits imposed under waste acceptance criteria, toxicity characteristic leaching procedure restrictions for secondary waste disposal, and air emission permits. Although there is currently no processing of tank waste at Hanford, waste processing is imminent, and representative mercury inventory tracking will be important to anticipate and mitigate stack emissions and secondary liquid waste disposal issues. A methodology to accurately determine total mercury and mercury speciation in Hanford tank waste, while maintaining low mercury detection limits, currently does not exist at Hanford. Moreover, the mercury species in the waste solids are unknown and may be waste type-specific. The development of an analytical method to separate and speciate mercury in tank waste was undertaken by the Pacific Northwest National Laboratory (PNNL) while leveraging an existing non-radiological, ultra-trace mercury detection technique frequently performed at PNNL's Marine Sciences Laboratory in Sequim, Washington. The ultimate goal of this work is to develop an analytical method to obtain detailed mercury speciation information and update flowsheet modeling assumptions related to mercury partitioning at Hanford. The first phase of testing was completed in the development of an analytical methodology for the low-level determination of total mercury, elemental mercury, methylmercury, and dimethylmercury in Hanford tank waste. This paper presents Phase I testing which focused on determining whether mercury species can be preconcentrated from aqueous Hanford tank waste solution onto a solid substrate, while simultaneously eliminating or very significantly reducing the parent radionuclide activity. This was demonstrated by developing protocols for the separation and preconcentration of total mercury and methylmercury onto solid substrates, then measuring the substrates for radiological content at PNNL's Radiochemical Processing Laboratory on the Hanford Site. The mercury content was successfully separated onto stable substrates and the radionuclide activity reduction was significant enough that the preconcentrated samples could be subjected to quantification using far less restrictive handling and radiological controls than would be required for the parent sample (i.e., contamination area fume hood vs. hot cell). This mercury separation method required no sample dilution, which enables maximum mercury detectability, while still allowing mercury speciation. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Electron nanoprobe induced oxidation: A simulation of direct-write purification

Electron beam direct-write has recently taken a large step forward with the advent of methods to purify deposits. This development has opened the door for future direct-write device prototyping and editing. In one such approach, an additional beam scanning procedure removes carbonaceous impurities via oxidation from metal–carbon deposits (e.g., PtC 5 ) in the presence of H 2 O or O 2 after deposition. So far, critical aspects of the oxidation reaction remain unclear; experiments reveal clearly that electron stimulated oxidation drives the process yet it is not understood why H 2 O purifies by a bottom-up mechanism while O 2 purifies from the top-down. The simulation results presented here suggest that the chemisorption of dissolved O 2 at buried Pt nanoparticle surfaces controls purification in the top-down case while both the high relative solubility coupled with weak physisorption of H 2 O explains the bottom-up process. Crucial too is the role that the carbonaceous contaminant itself has on the dissolution and diffusion of O 2 and H 2 O. The results pave the way for simulation driven experiments where (1) the transient densification of the deposit can be accounted for in the initial deposit design stage and (2) the deposition and purification steps can be combined.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

THE SCENARIOS APPROACH TO ATTENUATION-BASED REMEDIES FOR INORGANIC AND RADIONUCLIDE CONTAMINANTS

Guidance materials based on use of conceptual model scenarios were developed to assist evaluation and implementation of attenuation-based remedies for groundwater and vadose zones contaminated with inorganic and radionuclide contaminants. The Scenarios approach is intended to complement the comprehensive information provided in the US EPA's Technical Protocol for Monitored Natural Attenuation (MNA) of Inorganic Contaminants by providing additional information on site conceptual models and extending the evaluation to consideration of Enhanced Attenuation approaches. The conceptual models incorporate the notion of reactive facies, defined as units with hydrogeochemical properties that are different from surrounding units and that react with contaminants in distinct ways. The conceptual models also incorporate consideration of biogeochemical gradients, defined as boundaries between different geochemical conditions that have been induced by waste disposal or other natural phenomena. Gradients can change over time when geochemical conditions from one area migrate into another, potentially affecting contaminant mobility. A recognition of gradients allows the attenuation-affecting conditions of a site to be projected into the future. The Scenarios approach provides a stepwise process to identify an appropriate category of conceptual model and refine it for a specific site. Scenario materials provide links to pertinent sections in the EPA technical protocol and present information about contaminant mobility and important controlling mechanism for attenuation-based remedies based on the categories of conceptual models.

54 ENVIRONMENTAL SCIENCES↗

Arsenic stabilization performance of a novel starch-modified Fe-Mn binary oxide colloid

Arsenic (As) is an environmentally hazardous contaminant and can be a serious threat to human health. In China, remediation needs for a large number of As-contaminated sites renders a strong demand for efficient remedial reagents and cost effective approaches. In this study, a novel starch-modified Fe-Mn binary oxide (SFM), an amorphous colloidal material, has been synthesized as a remedial reagent and its As stabilization performance has been evaluated. A set of laboratory batch experiments were carried out by directly adding SFM of different dosages into three contaminated soils. Results demonstrated that SFM could transform As in soil from non-specifically and specifically sorbed fractions to the more stable form bounded to amorphous iron hydrous oxides, thus reducing the As concentration in TCLP leachates by 42.0-93.2%. Results from adsorption tests and microscopic analysis indicated that the interactions between SFM and As are mainly controlled by adsorption, oxidation, and precipitation processes. SFM has abundant surface hydroxyl groups, with excellent adsorption properties for both As(V) and As(III), with the maximum adsorption capacities of 160.63 and 284.64 mg/g respectively at pH 7.0. The adsorption process closely fitted pseudo second-order kinetics and Freundlich isotherm model. SFM could increase soil Eh and oxidize As(III) to As(V), which facilitated the As stabilization in soilColloidal iron-based material directly used for stabilization in As contaminated soils is reported here for the first time. Starch modification improves both the reactivity and mobility of SFM in soil. Our findings propose an efficient and convenient reagent for As remediation in soil.

Yan, Xiulan↗

Autonomous Sampling Platform Development: Radiological Contamination Mapping at SRS

From 1961 to 1964, radioactive elements were released from the Savannah River Site into local bodies of water via cooling water charges from the reactors on site. In 1983, the extent of the radioactive contamination was first studied, and elements such as 137 Cs, 90 Sr, 238 Pu, 241 Am, 244 Cm, and tritium were found to have seeped from local bodies of water into sediment and the surrounding flora and fauna. The current method of tracking and monitoring radioactive contamination at the SRS is to gather samples and conduct measurements in a laboratory. A cheaper, and safer, method to conduct such measurements would be to automate the process by using an autonomous boat that can travel to locations, conduct measurements, and return home all without human intervention. To introduce this idea, the construction of an autonomous boat prototype was completed to demonstrate the practicality and feasibility of such an idea. The prototype travels to a set of waypoints, stops at each waypoint, and returns when all waypoints have been reached. It does this by employing a simple battery-powered boat with an Arduino controller that steers the boat using a steering algorithm incorporated into a Proportional Integral Derivative (PID) function. A total of three tests were conducted at two different bodies of water; and after working out some hardware problems, the boat drone was able to successfully steer and reach all programmed waypoints. With the prototype complete, the next steps to realizing the final product of the boat drone will include adopting a processing unit with higher-bit architecture, using a bigger boat with a more powerful trolling motor, and incorporating a solar panel for continuous power and round-the-clock performance.

42 ENGINEERING↗