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At least 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
NASA NTRS2021

Tonlé Sap Food Security and Agriculture II: Evaluating Changes in Ecosystem Vitality and Freshwater Healthin the Tonlé Sap Basin using Remotely Sensed Data

The Tonlé Sap Lake and river basin in central Cambodia provide critical ecosystem services to the region, including fisheries, agricultural irrigation, hydropower, and biodiverse habitats. Deforestation, increased pumping for farming, and effects of climate change such as droughts and forest fires threaten the health of the lake and food security in the region. This project built upon the previous term through a partnership with Conservation International (CI), the Cambodian Ministry of Water Resources and Meteorology, and the Tonlé Sap Authority to assess ecosystem vitality and implement CI’s Freshwater Health Index (FHI) tool, in an effort to prioritize resource expenditure and highlight areas of concern. Due to the COVID-19 pandemic and related travel restrictions, partners had not been able to readily collect in situ data for the past year, which make up the majority of FHI inputs. To help fill this data gap, we developed a methodology for using Gravity Recovery and Climate Experiment (GRACE) satellite data to calculate groundwater storage depletion, and a Python Application Programming Interface for processing and formatting remotely-sensed data for the Soil and Water Assessment Tool (SWAT) model. We then used SWAT to model nutrient flows and of phosphorous, nitrogen and suspended sediments amounts in the basin from October 2000 to December 2020. These outputs served as inputs for the FHI and provided policy makers with robust monitoring information to aid decision-making in the area and safeguard the lake’s vital fisheries and biodiversity.

Justine Spore↗
DOE OSTI2025

Predictive Modeling and Uncertainty Quantification in Condition Monitoring of Active Components: A Reactor Coolant Pump Use Case

This work develops data-driven models for onset of thermal barrier leakage in reactor coolant pumps. It incorporates uncertainty quantification to enhance the reliability and robustness of pre- dictions. Using synthetic data generated by the Generic Pressurized Water Reactor simulator, realistic degradation scenarios were simulated across lifecycle stages—beginning, middle, and end of life. Key variables, including differential pressure, flow rate, vibration, and temperatures, were analyzed using machine learning framework. The fully connected neural network models demonstrated exceptional performance, achieving R2 scores exceeding 0.99 and root mean square errors as low as around 8.23 × 10-2 gallon per minute (gpm) for the three stages of the lifecy- cle. UQ analysis further validated the model’s robustness, with narrow uncertainty bounds during steady-state operations and appropriately wider bounds during transitional phases, reflecting the physical behavior of the system. This work addresses important gaps in real-time condition moni- toring and regulatory compliance by integrating advanced condition monitoring technologies with UQ into IST programs. The ability to detect thermal barrier leakage early and quantify prediction reliability supports optimizing maintenance strategies while ensuring nuclear power plants’ safe and reliable operation.

99 - GENERAL AND MISCELLANEOUS↗
DOE OSTI2014

Research in nondestructive evaluation techniques for nuclear reactor concrete structures

The purpose of the Materials Aging and Degradation (MAaD) Pathway of the Department of Energy's Light Water Reactor Sustainability (LWRS) Program is to develop the scientific basis for understanding and predicting longterm environmental degradation behavior of material in nuclear power plants and to provide data and methods to assess the performance of systems, structures, and components (SSCs) essential to safe and sustained nuclear power plant operations. The understanding of aging-related phenomena and their impacts on SSCs is expected to be a significant issue for any nuclear power plant planning for long-term operations (i.e. service beyond the initial license renewal period). Management of those phenomena and their impacts during long-term operations can be better enable by improved methods and techniques for detection, monitoring, and prediction of SSC degradation. The MAaD Pathway R and D Roadmap for Concrete, 'Light Water Reactor Sustainability Nondestructive Evaluation for Concrete Research and Development Roadmap', focused initial research efforts on understanding the recent concrete issues at nuclear power plants and identifying the availability of concrete samples for NDE techniques evaluation and testing. [1] An overview of the research performed by ORNL in these two areas is presented here.

42 ENGINEERING↗
DOE OSTI2013

The Northwest Geysers EGS Demonstration Project, California. Pre-stimulation Modeling and Interpretation of the Stimulation

The Northwest Geysers Enhanced Geothermal System (EGS) demonstration project aims to create an EGS by directly and systematically injecting cool water at relatively low pressure into a known High Temperature (280–400 °C) Zone (HTZ) located under the conventional (240 °C) geothermal steam reservoir at The Geysers geothermal field in California. Here we report that , the results of coupled thermal, hydraulic, and mechanical (THM) analyses made using a model developed as part of the pre-stimulation phase of the EGS demonstration project is presented. The model simulations were conducted in order to investigate injection strategies and the resulting effects of cold-water injection upon the EGS system; in particular to predict the extent of the stimulation zone for a given injection schedule. The actual injection began on October 6, 2011, and in this paper a comparison of pre-stimulation model predictions with micro-earthquake (MEQ) monitoring data over the first few months of a one-year injection program is presented. The results show that, by using a calibrated THM model based on historic injection and MEQ data at a nearby well, the predicted extent of the stimulation zone (defined as a zone of high MEQ density around the injection well) compares well with observed seismicity. The modeling indicates that the MEQ events are related to shear reactivation of preexisting fractures, which is triggered by the combined effects of injection-induced cooling around the injection well and small changes in steam pressure as far as half a kilometer away from the injection well. Pressure-monitoring data at adjacent wells and satellite-based ground-surface deformation data were also used to validate and further calibrate reservoir-scale hydraulic and mechanical model properties. The pressure signature monitored from the start of the injection was particularly useful for a precise back-calculation of reservoir porosity. Ultimately, the first few months of reservoir pressure and surface deformation data were useful for estimating the reservoir-rock permeability and elastic modulus. Finally, although the extent of the calculated stimulation zone matches the field observations over the first few months of injection, the observed surface deformations and MEQ evolution showed more heterogeneous behavior as a result of more complex geology, including minor faults and fracture zones that are important for consideration in the analysis of energy production and the long-term evolution of the EGS system.

58 GEOSCIENCES↗
NASA NTRS1979

Remote monitoring of a thermal plume

A remote-sensing experiment conducted on May 17, 1977, over the Surry nuclear power station on the James River, Virginia is discussed. Isotherms of the thermal plume from the power station were derived from remotely sensed data and compared with in situ water temperature measurements provided by the Virginia Electric and Power Company, VEPCO. The results of this study were also qualitatively compared with those from other previous studies under comparable conditions of the power station's operation and the ambient flow. These studies included hydraulic model predictions carried out by Pritchard and Carpenter and a 5-year in situ monitoring program based on boat surveys.

Kuo, C. Y.↗
NASA NTRS1986

Design, construction and long life endurance testing of cathode assemblies for use in microwave high-power transmitting tubes

The cathode life test program sponsored by NASA Lewis Research Center at Watkins-Johnson Company has been in continuous operation since 1972. Its primary objective has been to evaluate the long life capability of barium dispenser cathodes to produce emission current densities of 2 A sq. cm. or more in an operational environment simulating that of a highpower microwave tube. The life test vehicles were equipped with convergent flow electron guns, drift space tubes with solenoid magnets for electron beam confinement and water-cooled depressed collectors. A variety of cathode types has been tested, including GE Tungstate, Litton Impregnated, Philips Type B and M, Semicon types S and M, and Spectra-Mat Type M. Recent emphasis has been on monitoring the performance of Philips Type M cathodes at 2 A sq. cm. and Sprectra-Mat and Semicon Type M cathodes at 4 A sq. cm. These cathodes have been operated at a constant current of 616 mA and a cathode anode voltage on the order of 10 kV. Cathode temperatures were maintained at 1010 C true as measured from black body holes in the backs of the cathodes. This report presents results of the cathode life test program from July l982 through April l986. The results include hours of operation and performance data in the form of normalized emission current density versus temperature curves (Miram plots).

Batra, R.↗
DOE OSTI2015

2015 Long-Term Hydrologic Monitoring Program Sampling and Analysis Results Report for Project Rulison, Co

The U.S. Department of Energy (DOE) Office of Legacy Management conducted annual sampling at the Rulison, Colorado, Site for the Long-Term Hydrologic Monitoring Program (LTHMP) on May 20–22 and 27, 2015. Several of the land owners were not available to allow access to their respective properties, which created the need for several sample collection trips. This report documents the analytical results of the Rulison monitoring event and includes the trip report and the data validation package (Appendix A). The groundwater and surface water monitoring were shipped to the GEL Group Inc. laboratories for analysis. All requested analyses were successfully completed. Samples were analyzed for gamma-emitting radionuclides by high- resolution gamma spectrometry. Tritium was analyzed using two methods, the conventional tritium method, which has a detection limit on the order of 400 picocuries per liter (pCi/L), and the enriched method (for selected samples), which has a detection limit on the order of 3 pCi/L.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Solar Living House Final Technical Report

The Solar Living House is a high-performance solar-powered dwelling designed by a team of faculty and students from the University of Florida, in collaboration with Santa Fe College, the National University of Singapore, and Alachua Habitat for Humanity. The project was designed in accordance with the Solar Decathlon 2015, a research, design, education, and outreach program developed by the U.S. Department of Energy (DOE). The Solar Living House is fundamentally a house for living, centered on people and the activities of daily life while quietly introducing advanced design, construction, and engineering technologies. The 993 square-foot two-bedroom one-bath home was designed to embrace and frame an exterior courtyard space. This courtyard acts as an extension of the interior living spaces, maximizing the spatial potentials of a modest building footprint and introducing natural light into the primary living spaces of the house. Research Outcomes: The Solar Living House advances work on high-performance buildings through three principal technological innovations: wet/dry modular construction, a building automation system, and solar dehumidification systems. Wet / Dry Modular Construction: The house is designed as a series of five modules, including one that is designated as the “wet core.” The wet core consolidates the mechanical systems and bathroom into a single module to reduce plumbing runs, efficiency losses, and on-site construction time. The other four modules are designed to eliminate interior load bearing walls to allow for maximum flexibility in the reconfiguring of the space over time. The modules are designed to meet the structural challenges of both Florida’s hurricanes and California’s earthquakes. Building Automation System: The house is equipped with an integrated building automation system, allowing the houses environmental systems, lights, security systems, and smoke detectors to be programmed, monitored, and controlled through any mobile or computing device. These systems allow for more precise calibrations of temperature/humidity/lighting to correspond with user needs and preferences, minimizing energy losses with economical night- or day-time setbacks. Solar Dehumidification System: The most significant technological innovation in the Solar Living House is the solar thermal dehumidification system. This system generates hot water through two rooftop-mounted evacuated tube solar thermal collectors. The hot water is used to continually dry a regenerative solid desiccant material, typically white silica gel. The solid desiccant is used to adsorb moisture and humidity from the air without additional mechanical cooling. This strategy allows humidity to be modulated independently of air temperature, providing greater thermal comfort and reducing the opportunity for the growth of mold spores within the house while also reducing the overall energy consumption of the HVAC system. Economic Feasibility: The team set aggressive goals for affordability, targeting a construction cost of $138,710. An independent professional cost estimator determined the overall project costs, as designed, would be $333,799, or $336.15 per square foot of finished floor area. This is more than 2.4 times the target construction cost. By comparison, the average construction cost for a home in the United States in 2015 was $289,415, or $103.29 per square foot of finished floor area. Following work on the Solar Living House, team leaders incorporated many of its objectives into a net-zero energy home on a site in Gainesville, Florida. This site-built home avoided many of the constraints and complications of modular construction necessitated by the Solar Decathlon, allowing it to be built for a much more modest budget. This two-bedroom two bath 1,800 square foot home was constructed for $135.39 per square foot, including active photovoltaic solar systems, careful attention to continuous air barriers, increased insulation levels, and permanent site constructions. This project suggest that high-performance buildings can be realized for more modest budgets. Public Benefits: Work on the Solar Living House and Solar Decathlon 2015 offered our student team unparalleled learning opportunities. Because of the duration of the project, a number of students participated at different points in their education, from first year undergraduates all the way through to advanced graduate students. The opportunity for collaboration with students and faculty from the National University of Singapore was also extraordinary, allowing for a sharing of technical knowledge and cultural exchange. The wider public has benefited from this work as its findings have been shared through public presentations and publications. It serves as a useful stepping stone along the path towards affordable, high-performance buildings.

14 SOLAR ENERGY↗
NASA NTRSDate not supplied

NASA’s Student Airborne Science Activation for Minority Serving Institutions: Inaugural Program, Educational Outcomes, and Lessons Learned

The NASA Student Airborne Science Activation (SaSa) for Minority Serving Institutions (MSIs) held its inaugural summer research program for early career undergraduates interested in the Geosciences. SaSa is a NASA Science Activation funded 8-week summer internship program. Twenty-four first- and second-year undergraduates from MSIs across the U.S. participated in the summer program - June 6 to July 29, 2022. Students had the opportunity to gain hands-on research experience in all components of an airborne science campaign including flying on-board a NASA research aircraft to collect atmospheric measurements. Students conducted independent research projects related to the atmosphere, ocean, and geosciences that feed into NASA’s broader Earth Science Division’s and Decadal Survey goals using air quality, meteorological, and oceanic measurements from surface, airborne, and satellite-based observations. The program split its time between partner institution, University of Maryland Baltimore County and NASA’s Wallops Flight Facility in Wallops Island, Virginia. Students also made site visits at partner institutions, including: Hampton University, University of Maryland Eastern Shore, Morgan State University, Howard University, and Coppin State University and attended lectures from visiting faculty and NASA Subject Matter Experts. Students were guided on their research projects by near-peer graduate mentors, SaSa program leadership, co-Is at partner institutions, and NASA scientists to address two major research themes: 1) how human-caused air pollution has human and environmental implications, and 2) how large-scale meteorological factors influence local weather conditions. Students sorted into research groups, based on sub-discipline areas in the Geosciences, including: “Clouds, Aerosols and Radiation”, “Meteorology and Planetary Boundary Layer”, “Air Quality: Particle Pollution and Trace Gases”, and “Air-Water-Land Interface”. Their research was presented as 3-minute lightning talks and in-person poster presentations at a close-out event at NASA Goddard Space Flight Center in Greenbelt, Maryland. The students’ inter- and trans-disciplinary research experiences centered in the use of multiple ground, airborne, and satellite remote sensing NASA Earth Science Division assets. Providing a unique experience aligned to recognize the societal benefits that NASA contributes in the areas of resource management, air quality monitoring and policy decisions, energy and weather predictions, and research on the Earth’s climate. The SaSa program aims to increase the number of students from MSIs that identify as underrepresented or underserved individuals in the Geosciences discipline, Earth System Science graduate programs, and the NASA workforce. A summary of the summer research program, educational, scientific, and programmatic outcomes, as well as lessons learned will be presented.

NASA↗
DOE OSTI2019

2018 Long-Term Hydrologic Monitoring Program for Rio Blanco, Colorado, Site

This report for the third quarter (July 1–September 30) of calendar year (CY) 2018 includes information on the remedy-related surveillance, monitoring, and maintenance activities conducted at the Rocky Flats Site, Colorado. This report summarizes the maintenance and inspection of the two site landfills and four groundwater collection or treatment systems, inspection of the perimeter signs of the Central Operable Unit, erosion control and revegetation activities, and water monitoring.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

SRS Composite Analysis Monitoring Plan (FY2019 Model Validation)

Using a projected end-state date of 2065 (SRNS 2015b), the Savannah River Site (SRS) Composite Analysis (CA) modeling for each facility and waste site began on the inventory year assigned to it so that source depletion and radionuclide transport out of the system could be appropriately captured. Some SRS waste sites that have already achieved their end states (i.e. end-state inventories and end-state configuration) are currently contributing to the potential off-site public dose through source release, groundwater transport, discharge to on-site surface streams, and stream transport to the CA point of assessments (POAs). The inventory year assigned to these waste sites is 2002 or before. This means that SRS CA results from 2002 and beyond are a reasonable representation for these waste sites that have already achieved their end states and are currently contributing to the potential off-site public dose. The SRS Annual Environmental Report (AER) monitoring can differentiate and separate liquid pathway data allowing the data representing only waste sites at their end state to be produced. Because the SRS CA has projected reasonable end-state impacts from 2002 and beyond, and the AER monitoring can differentiate and separate operating and end-state contributions to annual liquid pathway release, an opportunity exists to use the AER monitoring data to validate the SRS CA model. The CA model validation program uses a graded and systematic approach for taking corrective action, starting with an SRS established administrative dose limit of 15 mrem/yr, below which no action is required. Based on the location of the 2010 SRS CA POAs, the only potential exposure pathway for the public is through surface water. The completion of the FY2019 CA model validation indicates that the SRS CA projected dose, while generally conservative, provides a reasonable representation of the maximum annual doses. These doses are well below the administrative limit; therefore, no additional action is required.

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

Developing Fugitive Emissions Sensor Networks

This document summarizes research performed under the Laboratory Directed Research and Development (LDRD) project titled Developing Fugitive Emissions Sensor Networks: New Optimization Algorithms for Monitoring, Measurement and Verification. The purpose of this project is to develop methods and software to enhance detection programs through optimal design of the sensor network. This project includes both software development and field work. While this project is focused on methane emissions, the sensor placement optimization framework can be applied to a wide range of applications, including the placement of water quality sensors, surveillance cameras, fire and chemical detectors. This research has the potential to improve national security by improving the way sensors are deployed in the field.

47 OTHER INSTRUMENTATION↗
NASA NTRS1977

Airborne monitoring of crop canopy temperatures for irrigation scheduling and yield prediction

The aim of the program discussed was to develop techniques for remotely measuring crop irrigation needs and predicting crop yields, with emphasis on wheat. Airborne measurements, using an IR line scanner and color IR photography, were made to evaluate the feasibility of measuring minimum and maximum (dawn and afternoon) crop temperatures to compute a parameter, termed 'stress degree day' (SDD) - a valuable indicator of crop water needs, which can be related to irrigation scheduling and yield. Crop canopy temperature measurements by airborne IR techniques revealed the superiority of thermal IR data over color IR photography. Water stress undetected in the latter technique was clearly detected in thermal imagery. Color IR photography, however, is valuable in discerning vegetation. The pseudo-colored temperature-difference images (and pseudo-colored images, reading directly in daily SDD increments) are shown to be well suited for assessing plant water status and, thus, for determining the irrigation needs and crop yield potentials.

Millard, J. P.↗
NASA NTRS1985

Orbital remote sensing - Space technology applications in south-east Asia

The evolution of remote sensing techniques in the developing countries of southeast Asia is reviewed. The use of the images for monitoring soil, water, and vegetation resources, in order to develop a national policy for conservation of the resources, is described. The remote sensing data are helpful in observing deforestation in southeast Asia; however, excessive cloud coverage does not allow accurate evaluation of the rice crop. The effects of the capabilities of the developing countries to process the data and remote sensing program of industrial countries on the future application of satellite imagery in developing countries are studied. The need for improved data banking and dissemination of the imagery is analyzed. Agreements on proprietary rights due to the improved ground resolution of orbital sensors are required. The designing of remote sensing equipment to meet the requirements of its users is discussed.

Malingreau, J.-P.↗
DOE OSTI2017

Next Generation RivGen Power System: Kvichak River, AK Overwinter Ice Study

The University of Alaska Fairbanks (UAF) Alaska Hydrokinetic Energy Research Center was tasked with developing a real-time data telemetry / remote power generation system to monitor frazil ice conditions in the Kvichak River in support of the U.S. Department of Energy funded "Next Generation MHK River Power System Optimized for Performance, Durability and Survivability" project. A real-time telemetry system was requested because of the short time span between the end of the frazil ice season when the instruments would be recovered, limited vessel availability and the project end-date. To meet the project objectives, UAF designed and assembled a remote power/real-time data telemetry system that included an auto start propane generator, a small PV array, a small battery bank and line-of-sight radios as well as two sonar systems to monitor river velocity and water column acoustic backscatter strength. Both sonars included internal batteries for powering the instruments in case of failure of the shore based power system. The sonars, deployed in ~5 m of water on the bed of the Kvichak River, adjacent to the Village of Igiugig, Alaska were tethered to shore via a waterproof armored cable that conveyed power to the subsurface instruments and data from the instruments to the shore based telemetry system. The instruments were programmed to record data internally as well as to transmit data serially over the cables to the shore based system. The system was in-place between November, 2016 and June, 2017. While the real-time data telemetry system was not successful and the remote power generation power system was only partially successful, the system design included sufficient redundant power in the form of internal instrument batteries to enable the collection of nearly three months of overlapping velocity and backscatter data (from November through February) and a record of acoustic backscatter strength spanning the entire ~150 day frazil ice season between November, 2016 and ~April, 2017. This submission includes the overwinter ice study plan, raw data, and report.

16 TIDAL AND WAVE POWER↗
DOE OSTI2016

Port Hope Area Initiative - Community Based Concepts Become Reality - 16538

The Port Hope Area Initiative (PHAI) involves the cleanup of historic low-level radioactive waste (LLRW) resulting from radium and uranium processing by the former Crown Corporation, Eldorado Nuclear Limited, and its predecessor companies, during the period between 1932 and 1988. The PHAI, which is based on a legal agreement between the Government of Canada and the adjacent municipalities of Port Hope and Clarington in Ontario, Canada, comprises two separate community-initiated projects for the long-term management of the historic LLRW located in each of these municipalities. The Port Hope Project involves the cleanup of approximately 1.2 million cubic metres of historic LLRW from various sites within the urban area of Port Hope, the construction and operation of an engineered aboveground mound where the waste will be safely contained, and the long-term maintenance and monitoring of the new waste management facility. The waste is currently located in 13 large-scale sites and an estimated 375 small-scale sites within the community. In contrast, the Port Granby Project involves the relocation of approximately 450,000 cubic metres of historic LLRW from the existing waste site on the north shore of Lake Ontario in rural Clarington, to a new engineered aboveground mound to be built 700 metres north of the shoreline. The work also involves the restoration of the existing site and long-term maintenance and monitoring the new facility. The PHAI entered Phase 2 (construction) of a three-phase program in early 2012, when $1.28 billion (Canadian) in federal funding was announced by the Minister of Natural Resources Canada. The funding, together with regulatory approval from the Canadian Nuclear Safety Commission (CNSC), which granted 10-year waste management licences to both projects, have permitted the PHAI to move forward with construction and remediation. Waste water treatment plants based on best-available technologies have been constructed for each project to remove a wide range of contaminants from groundwater, surface water and leachate collected during construction and operation of the aboveground mounds. Each treatment process has been designed to ensure the quality of treated water being discharged into Lake Ontario meets or exceeds stringent regulatory requirements, resulting in the enhanced protection of the Great Lakes Basin ecosystem. In 2015, the contract to build the Port Granby long-term waste management facility and remediate the existing waste site was awarded, and the long-awaited facility development will soon begin. The use of a dedicated internal waste transportation route along, which the LLRW will be trucked from the existing site to the new facility, is a key component of the design to minimize the impact on the local, rural community. In Port Hope, the removal of contaminated soil within the site for the new long-term management facility commenced in the fall of 2015. Over the next several years, multiple contracts will be awarded for construction and operation of the new waste management facility and remediation of the large and small-scale sites. In short, the Port Hope and Port Granby community-based concepts have matured into tangible projects with appropriate regulatory approvals and federal funding in place. Ongoing communications with the two communities have resulted in a well-informed public that understands the work to be done and is eager to see their projects take shape and become reality. As Canada's largest environmental remediation and restoration undertaking, the PHAI has never been closer to fulfilling its vision - working with the local communities to fulfil Canada's commitment for the cleanup of historic waste in Port Hope and Port Granby to leave an honourable legacy for future generations. (authors)

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

Large seasonal fluctuations of groundwater radioiodine speciation and concentrations in a riparian wetland in South Carolina

Recent studies evaluating multiple years of groundwater radioiodine ( 129 I) concentration in a riparian wetland located in South Carolina, USA identified strong seasonal concentration fluctuations, such that summer concentrations were much greater than winter concentrations. These fluctuations were observed only in the wetlands but not in the upland portion of the plume and only with 129 I, and not with other contaminants of anthropogenic origin: nitrate/nitrite, strontium-90, technecium-99, tritium, or uranium. This unexplained observation was hypothesized to be the result of strongly coupled processes involving hydrology, water temperature, microbiology, and chemistry. To test this hypothesis, an extensive historical groundwater database was evaluated, and additional measurements of total iodine and iodine speciation were made from recently collected samples. During the summer, the water table decreased by as much as 0.7 m, surface water temperature increased by as much as 15 °C, and total iodine concentrations were consistently greater (up to 680%) than the following winter months. Most of the additional iodine observed in the summer could be attributed to proportional gains in organo-iodine, and not iodide or iodate. Furthermore, 129 I concentrations were observed to be two-orders-of-magnitude greater at the bottom of the upland aquifer than at the top. A coupled hydrological and biogeochemical conceptual model is proposed to tie these observations together. First, as the surface water temperature increased during the summer, microbial activity was enhanced, which in turn stimulated the formation of mobile organo-I. Hydrological processes were also likely involved in the observed iodine seasonal changes: (1) as the water table decreased in summer, the remaining upland water entering the wetland was comprised of a greater proportion of water containing elevated iodine concentrations from the low depths, and (2) water flow paths in summer changed such that the wells intercepted more of the contaminant plume and less of the diluting rainwater (due to evapotranspiration) and streamwater (as the lower levels promote a predominantly recharging system). Furthermore, these results underscore the importance of coupled processes influencing contaminant concentrations, and the need to assess seasonal contaminant variations to optimize long-term monitoring programs of wetlands.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Prototype Demonstration of Gamma- Blind Tensioned Metastable Fluid Neutron/Multiplicity/Alpha Detector – Real Time Methods for Advanced Fuel Cycle Applications

The content of this report summarizes a multi-year effort to develop prototype detection equipment using the Tensioned Metastable Fluid Detector (TMFD) technology developed by Taleyarkhan [1]. The context of this development effort was to create new methods for evaluating and developing advanced methods for safeguarding nuclear materials along with instrumentation in various stages of the fuel cycle, especially in material balance areas (MBAs) and during reprocessing of used nuclear fuel. One of the challenges related to the implementation of any type of MBA and/or reprocessing technology (e.g., PUREX or UREX) is the real-time quantification and control of the transuranic (TRU) isotopes as they move through the process. Monitoring of higher actinides from their neutron emission (including multiplicity) and alpha signatures during transit in MBAs and in aqueous separations is a critical research area. By providing on-line real-time materials accountability, diversion of the materials becomes much more difficult. The Tensioned Metastable Fluid Detector (TMFD) is a transformational technology that is uniquely capable of both alpha and neutron spectroscopy while being “blind” to the intense gamma field that typically accompanies used fuel – simultaneously with the ability to provide multiplicity information as well [1-3]. The TMFD technology was proven (lab-scale) as part of a 2008 NERI-C program [1-7]. The bulk of this report describes the advancements and demonstrations made in TMFD technology. One final point to present before turning to the TMFD demonstrations is the context for discussing real-time monitoring of SNM. It is useful to review the spectrum of isotopes generated within nuclear fuel during reactor operations. Used nuclear fuel (UNF) from a light water reactor (LWR) contains fission products as well as TRU elements formed through neutron absorption/decay chains. The majority of the fission products are gamma and beta emitters and they represent the more significant hazards from a radiation protection standpoint. However, alpha and neutron emitting uranium and TRU elements represent the more significant safeguards and security concerns. Table 1.1 presents a representative PWR inventory of the uranium and actinide isotopes present in a used fuel assembly. The uranium and actinide isotopes (chiefly the Pu, Am and Cm elements) are all emitters of alpha particles and some of them release significant quantities of neutrons through spontaneous fissions

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗