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DOE OSTI2015

Digital Autoradiography as a novel complementary technique for the investigation of radioactive contamination in nuclear facilities under dismantlement

The detection (location and quantification) of nuclear facilities to be dismantled possible contamination with low-range particles emitters ({sup 3}H, other low-energy β emitters, a emitters) remains a tedious and expensive task. Indeed, usual remote counters show a too low sensitivity to these non-penetrating radiations, while conventional wipe tests are irrelevant for fixed radioactivity evaluation. The only method to accurately measure activity levels consists in sampling and running advanced laboratory analyses (spectroscopy, liquid scintillation counting, pyrolysis...). Such measurements generally induce sample preparation, waste production (destructive analyses, solvents), nuclear material transportation, long durations, and significant labor mobilization. Therefore, the search for the limitation of their number and cost easily conflicts with the necessity to perform a dense screening for sampling (to maximize the representativeness of the samples), in installations of thousands of square meters (floors, wells, ceilings), plus furniture, pipes, and other wastes. To overcome this contradiction, Digital Autoradiography (D. A.) was re-routed from bio molecular research to radiological mapping of nuclear installations under dismantling and to waste and sample analysis. After in-situ exposure to the possibly-contaminated areas to investigate, commercial reusable radiosensitive phosphor screens (of a few 100 cm{sup 2}) were scanned in the proper laboratory device and sharp quantitative images of the radioactivity could be obtained. The implementation of geostatistical tools in the data processing software enabled the exhaustive characterization of concrete floors at a rate of 2 weeks / 100 m{sup 2}, at lowest costs. Various samples such as drilled cores, or tank and wood pieces, were also successfully evaluated with this method, for decisive results. Thanks to the accurate location of potential contamination spots, this approach ensures relevant and representative sampling for further laboratory analyses and should be inserted in the range of common tools used in dismantling. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2017

Integrated Wash-Aid, Treatment, and Emergency Reuse System (IWATERS) for Strontium Contaminations - 17390

The Integrated Wash-Aid, Treatment, and Emergency Reuse System (IWATERS) is being developed to mitigate the release of radioactivity to the urban environment by disseminating, collecting, and processing decontamination wash water. Previously, IWATERS was designed for the treatment of surfaces contaminated with radioactive cesium. Experiments were performed to investigate the expansion of IWATERS for strontium contamination. Bench-scale tests were performed to investigate various counter-ions and chelators to promote ion exchange of strontium from building surfaces. Desorption results for Cs, Sr, and Eu from concrete aggregate and concrete, brick, and asphalt coupons using low- and high-pressure flow with Ca{sup 2+} and Ba{sup 2+} rich wash water are reported along with those from non-porous surfaces such as glass and vinyl siding. Several sorbents were tested for their ability to specifically separate Sr{sup 2+} from these high ionic strength wash waters. Alkali metal and alkaline earth salts were found to be effective counter-ions for decontamination of Sr{sup 2+}, which may facilitate the use of common sorbents, even if their K{sub d} values are <100 mL/g. In practice, low K{sub d} values require the use of large quantities of sorbent. Computer simulations were run using the GoldSim Contaminant Fate Module software package to optimize the efficiency of IWATERS for strontium and account for the technical limitations of the sorbents. This modeling allows greater flexibility to design the wash water recycling system for various end-user specifications including options from rain barrel designs for treating runoff from roofs and facades to larger options like drainage basins for larger-scale wash down activities. (authors)

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DOE OSTI2017

Defining Nature and Extent of Contamination for the Waste Management Area C RCRA Corrective Action Process at the Hanford Site in Southeast Washington - 17403

Determination of the nature and extent of contamination is a critical task in any Resource Conservation and Recovery Act of 1976 (RCRA) Facility Investigation. Nature and extent are typically defined through field investigation results. In some cases, however, physical and/or programmatic limitations on field work can impede efforts to define nature and extent based on field work alone. Both physical and programmatic restrictions affected efforts to characterize soil contamination at Waste Management Area C, on the U.S. Department of Energy's Hanford Site. As a result, fate and transport modeling was undertaken to enhance the definition of the nature and extent of soil contamination at Waste Management Area C. (authors)

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DOE OSTI2015

Scaling gas-phase treatment of vadose-zone contaminants for field application at the Hanford site - 15133

In situ vadose zone remediation approaches are being evaluated as potential options to mitigate the transport of inorganic and radionuclide contaminants from the vadose zone to the groundwater at the U.S. Department of Energy's Hanford site. Some of the candidate approaches are based on changing the contaminant or subsurface conditions in a way that slows downward migration of the contaminants through the vadose zone using amendments delivered in the gas-phase. Ammonia-vapor treatment of uranium relies on induced sediment dissolution and precipitation processes that decrease the amount of mobile uranium in the vadose zone. Previous laboratory studies have demonstrated the decrease in uranium mobility caused by ammonia treatment. As part of development efforts for the ammonia technology, scale-up issues were identified and have been addressed through a series of laboratory and modeling efforts. Key scale-up elements are scoping calculations to support treatment design and understanding ammonia transport. Recent research has extended the concept of geochemical manipulation by ammonia to investigate a combined-gas treatment for sequestering Tc-99 in the vadose zone. The technique uses a combination of geochemical Tc-99 reduction with hydrogen sulfide gas and induced sediment mineral dissolution and precipitation with ammonia vapor, creating conditions for deposition of stable precipitates that decrease the mobility of Tc-99. Laboratory experiments have demonstrated the effectiveness of this treatment under a variety of operational and sediment conditions important to the scale-up and evaluation of potential addition field applications. (authors)

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DOE OSTI2015

Modeling the effectiveness of remediation efforts in contaminated urban areas: An EMRAS II Urban Areas Working Group exercise - 15631

The Urban Areas Working Group was part of the IAEA's EMRAS II (Environmental Modelling for Radiation Safety) Programme during 2009-2011. The Working Group's goal was to test and improve the capabilities of models used in assessment of radioactive contamination in urban settings. The 'contaminant transport and countermeasures' exercise was focused on modeling the effectiveness of potential countermeasures or remediation efforts with respect to reduction of human exposures and doses. The exercise was based on a hypothetical situation involving an initial concentration of Co-60 or Pu-239 in air in a specified urban area. Participants were given detailed input information, including descriptions of test locations in two types of urban areas, (1) a business area with buildings and asphalt, and (2) a park area near an apartment town. Several kinds of initial weather conditions (dry, light rain, and heavy rain) were explored. Modeling endpoints included contamination densities, dose rates (from each contributing surface and total), annual and cumulative doses (internal and external) for specified reference individuals, and effectiveness of countermeasures and remediation efforts in terms of dose rate reduction and dose reduction. External doses were emphasized for Co-60 and internal doses for Pu-239. Approaches and model predictions from five models are compared, and explanations for similarities and differences among model predictions are offered. Understanding the effects of different approaches, assumptions, and parameter values is essential to a comparison of results from different models and to understanding both the usefulness and the limitations of any given model. (authors)

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2015

Study of an unrefined humate solution as a possible remediation method for groundwater contamination - 15698

Savannah River Site (SRS) was one of the major nuclear processing facilities in the U.S. where plutonium was produced during the Cold War. Approximately 1.8 billion gallons of low level acidic waste solution containing radionuclides and dissolved metals were discharged to a series of unlined seepage basins at the F/H Area. Uranium is a key contaminant of concern in the basin's groundwater. It is migrating into the groundwater creating an acidic plume with a pH between 3-5.5. Groundwater Actions: The pump-and-treat water treatment unit was designed and built in 1997 to remove metals and radionuclides. In 2004 a hybrid funnel-and-gate system was constructed to create a treatment zone in which the acidic nature of the contaminated sediments could be reversed. Huma-K is an organic fertilizer that comes from the alkaline extraction of leonardite (a low-rank coal). Huma-K has a high content of humic substances which consist of complex organic compounds formed by the decomposition of plant and animal tissue. The objective of this study is to determine if a low cost unrefined humate solution (Huma-K) can be used to facilitate uranium adsorption to control its mobility in acidic groundwater. This study can assist in evaluating whether Huma-K can be used as an in situ amendment for the remediation of groundwater contaminated with uranium. Sediments from FAW-1 70-90 ft were used in this experiment. Sediments were disaggregated and sieved to a particle size of . 2 mm. Concentrations in the range 10-500 ppm were tested. Once all the components were added, pH was adjusted to 4. Samples were vortex mixed and placed on a shaker table at 100 RPM for a period of 24 hours in order to reach the adsorption equilibrium. Once the adsorption equilibrate was reached, samples were centrifuged at 2700 RPM to separate the liquid and the solid phase. The liquid fraction was analyzed using a Thermo Scientific Genesys 10S UV-Vis spectrophotometer. The same experimental design was used as explained above. A known concentration of Huma-K was used to study the pH effect on the sorption process. pH values were measured at the beginning and at the end of the experiment. Spectra of Huma-K show a featureless character. Absorbance of light increases as the wavelength is decreased. Measurements were done at 254 nm due to the presence of aromatic rings. Apparently there are two sorption processes. The first one follows the same trend as the Langmuir isotherm up to 250 ppm. The second sorption process occurs after all the binding sites in the sediments have been occupied. Precipitation decreases as the pH is increased. Based on the sorption isotherm, humic substances apparently bind first to the binding sites of the sediments particles. Once all the binding sites have been occupied, other sorption processes may start to dominate. Sorption is affected by pH. Higher sorption is seen at low pH values. Increased precipitation at low pH values is probably due to the neutralization of surface charges of humic molecules making them agglomerate.

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DOE OSTI2016

Low-Altitude Unmanned Aerial Vehicles as a Tool for the Remediation of Radiologically Contaminated Environments - 16257

Following the events at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011, significant quantities of radioactive material were released into the local Japanese as well as the wider global environment. At the fifth anniversary of the incident, much work and expense is still being dedicated to the remediation of a large area of eastern Japan, contaminated primarily with radio-caesium. Due to the complex topography of the geographical area of Japan effected, it is important to understand contaminant evolution/migration at the greatest possible resolution - previous methods have lacked this. An increase in the spatial resolution of radiation mapping over other previous methods has been achieved through the deployment of an unmanned aerial vehicle (UAV). The platform used during this work combined a low-altitude multi-rotor UAV with a lightweight radiation mapping system to achieve sub-meter resolution. Using this system it was possible to measure the distribution of radionuclide contamination at a number of sites within the Fukushima Prefecture region of Japan. Unlike ground-based surveys conducted on foot by humans that attain a comparable resolution, such a system eliminates the potentially significant dose that would otherwise be received, as well as the influence of shielding on results. In addition to providing a rapid and high resolution response to radiological incidents, such monitoring technology has the potential to be a powerful tool in post-operational clean-out (POCO) at nuclear sites undergoing decommissioning worldwide. (authors)

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DOE OSTI2016

Utilization and Application of Kurion Mobile Processing System in Remediation of Radioactively Contaminated Water - 16370

Kurion{sup R} Mobile Processing Systems (KMPS) were deployed in Fukushima as first-of-a- kind at-tank isotope removal systems to remediate Sr from reverse osmosis concentrated salt water. The systems were successful in their efforts and achieved their decontamination and availability goals. The use of KMPS has been considered for other applications where a modular system is of benefit. The use of different Kurion Ion Specific Media (ISM) allows for precision removal of hazardous ions from a variety of waste streams. This paper describes a range of projects in which KMPS modularity will benefit the nuclear industry. The KMPS is a flexible system that can be deployed quickly and efficiently. One treatment system option being considered is the utilization of a KMPS for the removal of contamination from groundwater. Similar to its use in Japan, the KMPS can be sent to remote locations for the direct treatment of ground water. In particular, there are several sites across the world where uranium contamination is a problem. Uranium treatability testing was performed on collected groundwater samples from a radiologically contaminated site. The tests were used to help provide designs for KMPS modifications. These designs included the addition of chemical treatment module for the control of pH and other chemistry, the addition of an ultraviolet module for the destruction of biological material, among others. The tests determined the loading capacities of uranium capture resins (UCR) and media (UCM) for this specific waste stream. Based on uranium loading capacities of 37.3 mg/L (end of test C/C{sub 0} = 0.5) and 54.6 mg/L (extrapolated to C/C{sub 0} = 0.98), and the longevity of the resin (45,911 BV for C/C{sub 0} = 0.5, and 80,556 BV for C/C{sub 0} = 0.98) UCR-1 was selected as the media/resin to be proposed for a uranium treatment system. (authors)

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DOE OSTI2016

NitroJet{sup R}'s Verification Test of Contaminated Water Storage Tank Decontamination in Fukushima Daiichi Nuclear Power Plant - 16489

After the Fukushima Daiichi nuclear disaster, much radioactively contaminated water has generated and has been stored into tanks in the site. Therefore, these contaminated water storage tanks (flange-type) are severely required to be decontaminated in order to be dismantled or to be reused to store cleaner water with less radioactive liquid waste and exposure of workers. Then, IHI Corporation (hereinafter, IHI) have verified that NitroJet{sup R} had capability to decontaminate these tanks under governmental grant (the Validation of technologies for contaminated water management project in the FY2013 Supplementary Budget). For this verification, IHI achieved acquiring DF (decontamination factor) by fabricating radioactive partial mock-ups with Rb-86. Moreover, IHI have demonstrated remote operation of decontamination work by using tank's partially full-scale mock up. (authors)

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DOE OSTI2018

Autonomous Radiation Survey Inside Contaminated Buildings at Fukushima Daiichi with the Riser UAV - 18299

Nuclear decommissioning is constrained and defined by radiation and radioactive contamination. Where radiation is high and its distribution is unknown simply gathering the data needed for project planning can become a challenge. Fukushima Daiichi epitomises this challenge. The complex sequence of events at the plant following the March 2011 earthquake and tsunami has resulted in extensive physical damage and an essentially unpredictable distribution of contamination. TEPCO have applied a range of manual and robotics techniques to map the status of the plant, but many significant areas have remained no-go zones due to a combination of high radiation, physical hazards and obstacles. Further, even in areas where manual survey is feasible, there is strong desire to minimise human exposure to radiation by deploying robots where possible. Riser is a fully autonomous UAV equipped with an infrastructure-free 3D navigation and mapping system, inspection cameras and a CZT spectrometric measurement capability. The system has been custom designed specifically to meet the needs of the nuclear inspection. Riser is capable of accessing areas with dose rates of hundreds of milli-sievert per hour and producing 3D models and radiation surveys with accurately located data points. The data from Riser can subsequently be fused using Createc's N-Visage engine to produce three-dimensional contamination maps which can be used for predictive modelling of future D and D activity. Riser has been deployed at Fukushima Daiichi since March 2017. We present examples of data and analysis outputs, as well as general learning about deploying autonomous robots at a nuclear site. (authors)

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DOE OSTI2018

Design of Ad Hoc Filtration Beds for Treating Contaminated Waste Waters - 18385

We employed the GoldSim Contaminant Transport model to design a system of reactive filtration beds that may be used to selectively remove radioactive cesium and other radionuclides from contaminated waters. These filtration beds can be rapidly constructed ad hoc by using common materials that permit timely, in-field treatment of incoming contaminated waters generated during the response and recovery phase of a radioactive release event. Sensitivity analyses on the system parameters revealed simple relationships between the bed design and the expected breakthrough of cesium, allowing us to generate a concise set of look-up tables to aid the early responders. (authors)

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DOE OSTI2018

Addressing Excess Contaminated Facilities and Mercury Cleanup At the Department of Energy's Oak Ridge Reservation - 18408

The U.S. Department of Energy's Oak Ridge Office of Environmental Management (OREM) and its prime cleanup contractor, URS | CH2M Oak Ridge LLC (UCOR) are executing an aggressive program of cleanup and risk reduction in excess contaminated facilities on the Oak Ridge Reservation (ORR). Across the complex, DOE has designated more than 2,300 of its facilities 'excess'. Excess means 'nonoperational' and refers to a facility for which DOE no longer has a mission need. Many of these facilities pose high risk to workers and/or the environment. Delayed cleanup increases risk as well as cost. OREM and UCOR initiated a Working Group on Excess Facilities to identify and prioritize activities that are needed to enhance worker safety, minimize further degradation of the facilities, and reduce the environmental risk. Six Excess Contaminated Facilities projects on the ORR were identified as priorities. Three of the projects are located at ORNL - the Building 7500 Homogenous Reactor Experiment, the Building 3026 Radioisotope Development Laboratory and Buildings 3028/3029 Isotope Facilities. At Y-12, priority excess facilities include the Column Exchange Equipment (COLEX), the Alpha-4 Lithium Enrichment Facility and the Biology Complex Research Facilities. Work on these projects is aimed at stabilization of degraded higher risk facilities, characterization of conditions and hazards, removal of hazardous materials and placement of the facility in the lowest risk condition possible pending demolition. At the same time, DOE and UCOR are preparing to undertake a comprehensive program to remediate the presence of mercury in the water stemming from historical operations at the Y-12 National Security Complex. Over decades of operations, mercury migrated into the environment. Deteriorating conditions of large post-operation mercury-use buildings may be contributing to additional releases. Mercury cleanup is a high priority for Y-12 and the Oak Ridge Reservation. UCOR is completing the final design on a new Mercury Treatment Facility with construction expected to begin in late 2017. When constructed the treatment facility will reduce the amount of mercury in local waters, lower environmental contamination levels and serve as a guard against future releases. (author)

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DOE OSTI2018

3D Time-Lapse Geophysical Imaging Evaluation of Contaminant Migration at the Hanford BY Cribs Site - 18504

Changes in bulk electrical conductivity are governed in large part by two diagnostic parameters concerning the state of vadose zone contamination: saturation and pore fluid conductivity. As a robust, remote, non-invasive, three-dimensional, and scalable imaging tool, time-lapse electrical resistivity tomography (ERT) can provide extensive diagnostic information concerning vadose zone contaminant distribution and migration by imaging changes in bulk electrical conductivity. We demonstrate long-term surface ERT monitoring of a ∼70-m-thick contaminated vadose zone to investigate whether rising groundwater nitrate levels are caused by unanticipated vadose zone flux. A three-dimensional time-lapse image spanning 10 years (2007-2017) reveals the impacts of meteoric surface infiltration events, but ultimately supports the adequacy of current conceptual understanding by indicating that rising nitrate levels are not sourced in the vadose zone. (authors)

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DOE OSTI2019

Panel Session 11: Featured Country Canada - Remediation of Contaminated Sites

Canada has several unique sites requiring environmental remediation of radiological contaminants. This panel was designed to outline the remediation of contaminated sites across Canada from several perspectives. Remote legacy uranium mining operations, small scale residential locations, and large impacted soil sites all pose different challenges, however there are some common solutions and keys to success. This panel addressed several of those challenges and provided lessons learned on how to successfully plan and execute large scale environmental remediation in both remote and residential locations. This panel focused on the cleaning up several contaminated sites in Canada and monitoring the long-term performance of sites that have already been remediated. Panelists addressed the technical and social challenges associated with various cleanup initiatives North of the 49. Parallel and the solutions that have been adopted to enable these projects to move forward. The panel offered the perspectives of owners, contractors and regulators on current projects and how they are leveraging past experience and learning from others to ensure future undertakings are successful. Presentations proposed include: 1 - Regulating Environmental Remediation in Canada (Michael Rinker, Canadian Nuclear Safety Commission (Canada)); 2 - Integration of Local Knowledge and Engagement/Capacity Building Legacy Uranium Mine Sites (Joe Muldoon, Saskatchewan Research Council (Canada)); 3 - The Path to Institutional Control - Safe, Secure and Stable (R. Liam Mooney, Cameco Corporation (Canada)); 4 - Port Hope Area Initiative: Project Challenges (Scott Parnell, Canadian Nuclear Laboratories (Canada))

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DOE OSTI2019

Occurrence of Radiological Contamination in Urban Parks Established over Former Landfill Sites - 19433

In 2005, the National Park Service was notified that elevated radiation levels were detected at Great Kills Park during a baseline radiological mapping effort conducted by the Counter Terrorism Bureau of the New York City Police Department and the United States Department of Energy. Great Kills Park is in the Staten Island Unit of Gateway National Recreation Area. A records search determined that approximately 1.1 x 10{sup 6} square meters (280 acres) of the park was established over an area in which the New York City Department of Sanitation placed approximately 1.2 x 10{sup 7} cubic meters (15.1 million cubic yards) of waste fill from 1944 to 1948. Since 2005, a series of response actions and investigations were conducted on behalf of the National Park Service to mitigate risk to human health and the environment and to determine the nature of radiological contamination at Great Kills Park. The findings support that radiological contamination is related to certain components of waste fill, including incinerator residue from both on and offsite incinerators, coal ash from the historical use of coal-fired boilers for heating, and incidental radiological artifacts in the waste fill due to their historical use and subsequent disposal. A majority of the radiological artifacts were determined to contain Ra-226 and included radioluminescent markers, radium buttons, radium paint containers, and brachytherapy devices. The National Park Service is currently performing a Remedial Investigation for the waste-filled area of Great Kills Park under the Comprehensive Environmental Response, Compensation and Liability Act. Several other Parks in Gateway National Recreation Area were established in areas with a similar history to Great Kills Park, and overlie waste fill historically placed during landfilling operations. Recently, radiological surveys were performed over limited portions of Spring Creek Park in the Jamaica Bay Unit of Gateway National Recreation Area. These surveys identified several locations with gamma radiation levels above the ambient level, several of which were attributable to radiological artifacts similar in nature to those recovered at Great Kills Park. Ongoing investigations at Great Kills Park and the recent findings at Spring Creek Park suggest that radiological contamination may be associated with historical landfilling practices that were common prior to the regulation and control of radioactive materials. (authors)

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DOE OSTI2019

Final Status Surveys of Subsurface Contaminated Areas - 19473

This paper addresses how the U.S. Army Corps of Engineers (USACE) has performed final status surveys (FSS) at sites with subsurface contaminated areas. The Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) guidance addresses only surficial contamination. This paper will explore alternative methodologies used by the USACE to demonstrate compliance with the release criterion when contamination extends below the surface. Special challenges posed by small areas of elevated activity at depth will also be addressed. (authors)

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DOE OSTI2019

Indoor Radon Measurements from Residential Buildings with Basements in a Community with Potential LLRW Contamination - 19566

The Port Hope Area Initiative (PHAI) represents the Government of Canada's commitment to the cleanup and safe, local, long-term management of historic low-level radioactive waste (LLRW) in two Southern Ontario municipalities-Port Hope and Clarington. The PHAI (see reference for internet address) is based on community-recommended solutions for the cleanup and safe long-term management of approximately 1.7 million cubic meters of LLRW. It is currently one of Canada's largest environmental remediation projects at a cost of over one billion dollars. Canadian Nuclear Laboratories (CNL) is implementing the PHAI on behalf of Atomic Energy of Canada Limited, a Federal Crown Corporation. An initial characterization and remediation program in the urban area of Port Hope was conducted from 1976 to 1981. The waste is the result of radium and uranium processing in Port Hope by the former Federal Crown Corporation Eldorado Nuclear Limited between 1933 and 1988. One contaminant of concern in the LLRW is radium-226 (Ra-226) which may lead to elevated indoor levels of radon-222 (Rn-222) indoors. As part of CNL's implementation of the PHAI, Arcadis is conducting the Port Hope Project Property Radiological Survey of approximately 4,800 small-scale sites to identify 1) properties that have not been affected by historic operations and 2) properties that have residual historic low-level radioactive waste impacts requiring remediation either for soils or for interior contamination or both. Over the last six years, a component of the Small Scale Sites (SSS) characterization surveys have measured radon concentrations in essentially all buildings in Port Hope using alpha-track detectors. All properties had subsurface characterization including analytical characterization and lithology following the radon measurement reporting to measure if soil concentrations exceeded the PHAI Cleanup Criteria (PHAI CC) for Ra-226 of 0.29 Bq/g. Buildings with radon gas exceeding a trigger level of 200 becquerels per cubic meter (Bq/m{sup 3}) or those with ventilation systems required investigation of soil concentrations around the perimeter of the building. Ra-226 concentrations above the background level of 0.05 Bq/g due to LLRW sources were forwarded to create remedial action plans (RAPs) to remove the contamination near the building. The SSS surveys provide a substantive data set on the approximately 3,000 properties measured to date with interior Rn-222 gas measurements and descriptions of the physical characteristics of the buildings, the lithology of soils near the buildings and the measurements of Ra-226 concentration in the soils on the property. Consideration of the potential for contribution from non-LLRW Ra-226 from natural sources or coal ash was required on some properties. This paper describes the data and exploratory analysis of the relationship(s) between LLRW and non-LLRW factors that affect the variation in indoor radon concentrations. Historical information on the urban area, the measured Ra-226 concentration and the age of the building were correlated with radon concentrations. A large variety of native soils are found in the complex terrain and the type of native soil was correlated with the radon concentrations. A statistical analysis to address the impact of co-related explanatory variables to model indoor radon concentrations is planned when the SSS activities are complete. (authors)

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DOE OSTI2020

Large Volume Airborne Contamination Monitoring To Support Nuclear Processes' Deactivation and Decommissioning

Current D and D operations at Hanford have demonstrated a flaw in the current state of the art capability of defining airborne contamination boundaries - Airborne particulate emissions of Pu-239 from CM2H operations on the Hanford Pu Finishing Plant were detected well beyond areas controlled for airborne Pu, putting numerous workers at risk for radiological assimilations - Current air samplers and CAM systems were surveying insufficient volumes of air to accurately predict where respiratory protection was required - Hanford is located in a high radon environment, making air monitoring for alpha emitting actinides challenging in high alpha radon induced backgrounds. - Inexpensive HEPA based home and industrial air purifiers filter significantly higher volumes of air than commercially available continuous-air monitoring (CAM) systems. - Inexpensive models capable of filtered air volumes exceeding 1000 times that of a CAM. - Detector system can be built to detect x-rays generated from actinide decay. - Branching ratios of x-rays are 4 orders of magnitude more intense from Plutonium decay than its gamma emissions. - Detector system can be a low resolution systems, as x-ray region of interest is not terribly congested. - Detection systems evaluated will be designed based on slabs of NaI or pixelated NaI or CsI panels. - Simple graphical user interface software will be developed to operate the detection system. - Concept is to deploy some of these air-purifying systems in nonradiological areas around SRNL to confirm radon can be rejected with confidence. - Generate some filters contaminated with plutonium via electroplated Pu or lab generated simulated particles. - then deploy units in known airborne radiological environments to establish systems ability to accurately measure actinide based hot particles Lab analyses will follow up the system analyses to ensure hot particles were correctly identified. Analysis by Scintillation: - Application of scintillation media to the surface of the filters is being explored. - Evaluating slabs of ZnS(Ag), application of powdered ZnS(Cu) and spray on Perkin Elmer Enhance. - Scintillation events would then be digitized with a digital camera and quantified. - Comparing against sensitivity of a PMT or SiPD readout. - Currently evaluating a Thorlabs 8 Megapixel Monochrome Scientific CCD Camera, hermetically sealed cooled package with a wide angle lens. - Wide angle lens allows complete view of HEPA filter from 7 inches away. - Images taken of glow in the dark paint, as well as plutonium-induced fluorescence. - Plutonium was flamed mounted on a 1 inch diameter stainless steel planchet, covered with a layer of mylar and a section of scintillating ZnS obtained from Eljon. - Currently working on reducing signal-to-noise levels to boost sensitivity. - Dark box to hold contaminated or electroplated source covered filters under fabrication. Analysis by x-ray Spectroscopy: - Branching ratios for x-ray emissions from Plutonium isotopes are orders of magnitude more intense than gamma-ray emissions. - The nuclear databases are incomplete on the branching ratios of some of the isotopes. - Evaluating some custom built SrI2 x-ray spectrometers vs a conventional windowed NaI detector. - SrI2 detectors are carbon-composite-windowed 51 mm x 51 mm. - MCNP calculations to establish self absorbance of filter media on 17 keV x-ray. Radon Rejection: - Activated charcoal pre-filter acts as a Radon trap. - Adding a time lapse feature to camera to aid in radon rejection. SRS Plutonium Fuel Form D and D Operations: Currently deploying air sampler to D and D operation of Pu-238 facility at SRS to generate some field samples to analyze.

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