SEARCH · Search NASA

Results for “RADIOACTIVE AEROSOLS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6

All sources NASA NTRS DOE OSTI

DOE OSTI2012

Efficiency and Loading Evaluation of High Efficiency Mist Eliminators (HEME) - 12003

High efficiency mist eliminators (HEME) are filters primarily used to remove moisture and/or liquid aerosols from an air stream. HEME elements are designed to reduce aerosol and particulate load on primary High Efficiency Particulate Air (HEPA) filters and to have a liquid particle removal efficiency of approximately 99.5% for aerosols down to sub-micron size particulates. The investigation presented here evaluates the loading capacity of the element in the absence of a water spray cleaning system. The theory is that without the cleaning system, the HEME element will suffer rapid buildup of solid aerosols, greatly reducing the particle loading capacity. Evaluation consists of challenging the element with a waste surrogate dry aerosol and di-octyl phthalate (DOP) at varying intervals of differential pressure to examine the filtering efficiency of three different element designs at three different media velocities. Also, the elements are challenged with a liquid waste surrogate using Laskin nozzles and large dispersion nozzles. These tests allow the loading capacity of the unit to be determined and the effectiveness of washing down the interior of the elements to be evaluated. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2016

The kinetics of aerosol particle formation and removal in NPP severe accidents

Severe Nuclear Power Plant (NPP) accidents are accompanied by release of a massive amount of energy, radioactive products and hydrogen into the atmosphere of the NPP containment. A valid estimation of consequences of such accidents can only be carried out through the use of the integrated codes comprising a description of the basic processes which determine the consequences. A brief description of a coupled aerosol and thermal–hydraulic code to be used for the calculation of the aerosol kinetics within the NPP containment in case of a severe accident is given. The code comprises a KIN aerosol unit integrated into the KUPOL-M thermal–hydraulic code. Some features of aerosol behavior in severe NPP accidents are briefly described.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2013

Aerosol Formation from High-Pressure Sprays for Supporting the Safety Analysis for the Hanford Waste Treatment and Immobilization Plant - 13183

The Waste Treatment and Immobilization Plant (WTP) at Hanford is being designed and built to pretreat and vitrify waste currently stored in underground tanks at Hanford. One of the postulated events in the hazard analysis for the WTP is a breach in process piping that produces a pressurized spray with small droplets that can be transported into ventilation systems. Literature correlations are currently used for estimating the generation rate and size distribution of aerosol droplets in postulated releases. These correlations, however, are based on results obtained from small engineered nozzles using Newtonian liquids that do not contain slurry particles and thus do not represent the fluids and breaches in the WTP. A test program was developed to measure the generation rate, and the release fraction which is the ratio of generation rate to spray flow rate, of droplets suspended in a test chamber and droplet size distribution from prototypic sprays. A novel test method was developed to allow measurement of sprays from small to large breaches and also includes the effect of aerosol generation from splatter when the spray impacts on walls. Results show that the release fraction decreases with increasing orifice area, though with a weaker dependence on orifice area than the currently-used correlation. A comparison of water sprays to slurry sprays with 8 to 20 wt% gibbsite or boehmite particles shows that the presence of slurry particles depresses the release fraction compared to water for droplets above 10 μm and increases the release fraction below this droplet size. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2010

Encapsulation of caesium-loaded Ionsiv in cement

The microporous material Ionsiv is used for {sup 137}Cs removal from aqueous nuclear waste streams. In the UK, Cs-loaded Ionsiv is classed as an intermediate-level waste; no sentencing and disposal route is yet defined for this material and it is currently held in safe interim storage on several nuclear sites. In this study, the suitability of fly ash and blast furnace slag blended cements for encapsulation of Cs-Ionsiv in a monolithic wasteform was investigated. No evidence of reaction or dissolution of the Cs-Ionsiv in the cementitious environment was found by scanning electron microscopy and X-ray diffraction. However, a small fraction ({<=} 1.6 wt.%) of the Cs inventory was released from the encapsulated Ionsiv during leaching experiments carried out on hydrated samples. Furthermore, it was evident that K and Na present in the cementitious pore water exchanged with Cs and H in the Ionsiv. Therefore, cement systems lower in K and Na, such as slag based cements, showed lower Cs release than the fly ash based cements.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2013

Experimental Challenges and Successes in Measuring Aerosol Concentrations at Prototypic Spray Conditions Encountered at the Hanford Waste Treatment and Immobilization Plant - 13327

To date, majority of the work done on measuring aerosol releases from failure of process piping was done using simple Newtonian fluids and small engineered-nozzles that do not accurately represent the fluids and breaches postulated during accident analysis at the Hanford Waste Treatment and Immobilization Plant (WTP). In addition, the majority of the work conducted in this area relies on in-spray measurements that neglect the effect of splatter and do not yield any information regarding aerosol generation rates from this additional mechanism. In order to estimate aerosol generation rates as well as reduce the uncertainties in estimating the aerosol release fractions over a broad range of breaches, fluid properties and operating conditions encountered at the WTP, the Pacific Northwest National Laboratory (PNNL) has designed, commissioned, and tested two experimental test stands. The first test stand, referred to as the large-scale test stand, was designed specifically to measure aerosol concentrations and release fractions under prototypic conditions of flow and pressure for a range of breaches postulated in the hazard analysis for 0.076 m (3-inch) process pipes. However, the size of the large-scale test stand, anticipated fluid loss during a breach, experimental risks, and costs associated with hazardous chemical simulant testing limited the large-scale test stand utility to water and a few non-hazardous physical simulants that did not fully span the particle size and rheological properties of the fluids encountered at the WTP. Overcoming these limitations and extending the range of simulants used, required designing and building a smaller test stand, which was installed and operated in a fume hood. This paper presents some of the features of both test stands, the experimental challenges encountered, and successes in measuring aerosol concentration in both test stands over a range of test conditions. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2018

Respirable Release Fraction Measurement Chamber (RRFMC) - 18321

The Respirable Release Fraction Measurement Chamber (RRFMC) is designed to hoist a container to a predetermined height, drop it, and then utilize aerosol particle counters to measure the mass of powder that is released from failed containers. The RRFMC hoist mechanism is located inside an airtight (6.1 m high) steel enclosure that isolates the released test aerosol from the surrounding lab room environment. Accurate measurement of the released test powder is necessary for estimating the total released mass of material. Cerium oxide will be used as a surrogate for plutonium oxide. The range of the aerodynamic diameter of cerium oxide test powder was characterized both by cascade impaction and aerodynamic sizing. The scope of this paper includes the physical parameters required for accurately measuring the total mass of released powder, the fabrication of the tower, various strategies to optimize concentration sampling, and developing methods to accurately measure the respirable fraction, airborne release fraction, and the damage ratio. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2015

Assessment of the LV-C2 Stack Sampling Probe Location for Compliance with ANSI/HPS N13.1-1999

This document reports on a series of tests conducted to assess the proposed air sampling location for the Hanford Tank Waste Treatment and Immobilization Plant (WTP) Low-Activity Waste (LAW) C2V (LV-C2) exhaust stack with respect to the applicable criteria regarding the placement of an air sampling probe. Federal regulations require that a sampling probe be located in the exhaust stack according to the criteria established by the American National Standards Institute/Health Physics Society (ANSI/HPS) N13.1-1999, Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stack and Ducts of Nuclear Facilities. These criteria address the capability of the sampling probe to extract a sample that represents the effluent stream. The tests were conducted on the LV-C2 scale model system. Based on the scale model tests, the location proposed for the air sampling probe in the scale model stack meets the requirements of the ANSI/HPS N13.1-1999 standard for velocity uniformity, flow angle, gas tracer and particle tracer uniformity. Additional velocity uniformity and flow angle tests on the actual stack will be necessary during cold startup to confirm the validity of the scale model results in representing the actual stack.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2011

Aerosol Resuspension Model for MELCOR for Fusion and Very High Temperature Reactor Applications

Dust is generated in fusion reactors from plasma erosion of plasma facing components within the reactor’s vacuum vessel (VV) during reactor operation. This dust collects in cooler regions on interior surfaces of the VV. Because this dust can be radioactive, toxic, and/or chemically reactive, it poses a safety concern, especially if mobilized by the process of resuspension during an accident and then transported as an aerosol though out the reactor confinement building, and possibly released to the environment. A computer code used at the Idaho National Laboratory (INL) to model aerosol transport for safety consequence analysis is the MELCOR code. A primary reason for selecting MELCOR for this application is its aerosol transport capabilities. The INL Fusion Safety Program (FSP) organization has made fusion specific modifications to MELCOR. Recent modifications include the implementation of aerosol resuspension models in MELCOR 1.8.5 for Fusion. This paper presents the resuspension models adopted and the initial benchmarking of these models.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2016

A system for monitoring the radiation effects of a proton linear accelerator

The system for real-time monitoring of radioactivity of a high-current proton linear accelerator detects secondary neutron emission from proton beam losses in transport channels and measures the activity of radionuclides in gas and aerosol emissions and the radiation background in the environment affected by a linear accelerator. The data provided by gamma, beta, and neutron detectors are transferred over a computer network to the central server. The system allows one to monitor proton beam losses, the activity of gas and aerosol emissions, and the radiation emission level of a linear accelerator in operation.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2011

Environmental impact of APC residues from municipal solid waste incineration: Reuse assessment based on soil and surface water protection criteria

Highlights: > The Dutch Building Material Decree (BMD) was used to APC residues from MSWI. > BMD is a straightforward tool to calculate expectable loads to the environment of common pollutants. > Chloride load to the environment lead to classification of building material not allowed. > At least a pre-treatment (e.g. washing) is required in order to remove soluble salts. > The stabilization with phosphates or silicates eliminate the problem of heavy metals. - Abstract: Waste management and environmental protection are mandatory requirements of modern society. In our study, air pollution control (APC) residues from municipal solid waste incinerators (MSWI) were considered as a mixture of fly ash and fine particulate solids collected in scrubbers and fabric filters. These are hazardous wastes and require treatment before landfill. Although there are a number of treatment options, it is highly recommended to find practical applications rather than just dump them in landfill sites. In general, for using a construction material, beyond technical specifications also soil and surface water criteria may be used to ensure environmental protection. The Dutch Building Materials Decree (BMD) is a valuable tool in this respect and it was used to investigate which properties do not meet the threshold criteria so that APC residues can be further used as secondary building material. To this end, some scenarios were evaluated by considering release of inorganic species from unmoulded and moulded applications. The main conclusion is that the high amount of soluble salts makes the APC residues a building material prohibited in any of the conditions tested. In case of moulding materials, the limits of heavy metals are complied, and their use in Category 1 would be allowed. However, also in this case, the soluble salts lead to the classification of 'building material not allowed'. The treatments with phosphates or silicates are able to solve the problem of heavy metals, but difficulties with the soluble salts are still observed. This analysis suggests that for APC residues to comply with soil and surface water protection criteria to be further used as building material at least a pre-treating for removing soluble salts is absolutely required.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2012

Bio-processing of solid wastes and secondary resources for metal extraction - A review

Highlights: Black-Right-Pointing-Pointer Review focuses on bio-extraction of metals from solid wastes of industries and consumer goods. Black-Right-Pointing-Pointer Bio-processing of certain effluents/wastewaters with metals is also included in brief. Black-Right-Pointing-Pointer Quantity/composition of wastes are assessed, and microbes used and leaching conditions included. Black-Right-Pointing-Pointer Bio-recovery using bacteria, fungi and archaea is highlighted for resource recycling. Black-Right-Pointing-Pointer Process methodology/mechanism, R and D direction and scope of large scale use are briefly included. - Abstract: Metal containing wastes/byproducts of various industries, used consumer goods, and municipal waste are potential pollutants, if not treated properly. They may also be important secondary resources if processed in eco-friendly manner for secured supply of contained metals/materials. Bio-extraction of metals from such resources with microbes such as bacteria, fungi and archaea is being increasingly explored to meet the twin objectives of resource recycling and pollution mitigation. This review focuses on the bio-processing of solid wastes/byproducts of metallurgical and manufacturing industries, chemical/petrochemical plants, electroplating and tanning units, besides sewage sludge and fly ash of municipal incinerators, electronic wastes (e-wastes/PCBs), used batteries, etc. An assessment has been made to quantify the wastes generated and its compositions, microbes used, metal leaching efficiency etc. Processing of certain effluents and wastewaters comprising of metals is also included in brief. Future directions of research are highlighted.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2012

Comparing urban solid waste recycling from the viewpoint of urban metabolism based on physical input-output model: A case of Suzhou in China

Highlights: Black-Right-Pointing-Pointer Impacts of solid waste recycling on Suzhou's urban metabolism in 2015 are analyzed. Black-Right-Pointing-Pointer Sludge recycling for biogas is regarded as an accepted method. Black-Right-Pointing-Pointer Technical levels of reusing scrap tires and food wastes should be improved. Black-Right-Pointing-Pointer Other fly ash utilization methods should be exploited. Black-Right-Pointing-Pointer Secondary wastes from reusing food wastes and sludge should be concerned. - Abstract: Investigating impacts of urban solid waste recycling on urban metabolism contributes to sustainable urban solid waste management and urban sustainability. Using a physical input-output model and scenario analysis, urban metabolism of Suzhou in 2015 is predicted and impacts of four categories of solid waste recycling on urban metabolism are illustrated: scrap tire recycling, food waste recycling, fly ash recycling and sludge recycling. Sludge recycling has positive effects on reducing all material flows. Thus, sludge recycling for biogas is regarded as an accepted method. Moreover, technical levels of scrap tire recycling and food waste recycling should be improved to produce positive effects on reducing more material flows. Fly ash recycling for cement production has negative effects on reducing all material flows except solid wastes. Thus, other fly ash utilization methods should be exploited. In addition, the utilization and treatment of secondary wastes from food waste recycling and sludge recycling should be concerned.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2011

Reducing volatilization of heavy metals in phosphate-pretreated municipal solid waste incineration fly ash by forming pyromorphite-like minerals

This research investigated the feasibility of reducing volatilization of heavy metals (lead, zinc and cadmium) in municipal solid waste incineration (MSWI) fly ash by forming pyromorphite-like minerals via phosphate pre-treatment. To evaluate the evaporation characteristics of three heavy metals from phosphate-pretreated MSWI fly ash, volatilization tests have been performed by means of a dedicated apparatus in the 100-1000 deg. C range. The toxicity characteristic leaching procedure (TCLP) test and BCR sequential extraction procedure were applied to assess phosphate stabilization process. The results showed that the volatilization behavior in phosphate-pretreated MSWI fly ash could be reduced effectively. Pyromorphite-like minerals formed in phosphate-pretreated MSWI fly ash were mainly responsible for the volatilization reduction of heavy metals in MSWI fly ash at higher temperature, due to their chemical fixation and thermal stabilization for heavy metals. The stabilization effects were encouraging for the potential reuse of MSWI fly ash.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2011

Utilization of municipal solid waste incineration fly ash for sulfoaluminate cement clinker production

Highlights: > The replacement can be taken up to 30% of MSWI fly ash in the raw mix. > The novelty compositional parameters were defined, their optimum values were determined. > Expansive property of SAC is strongly depended on gypsum content. > Three leaching test methods are used to assess the environmental impact. - Abstract: The feasibility of partially substituting raw materials with municipal solid waste incineration (MSWI) fly ash in sulfoaluminate cement (SAC) clinker production was investigated by X-ray diffraction (XRD), compressive strength and free expansion ratio testing. Three different leaching tests were used to assess the environmental impact of the produced material. Experimental results show that the replacement of MSWI fly ash could be taken up to 30% in the raw mixes. The good quality SAC clinkers are obtained by controlling the compositional parameters at alkalinity modulus (C{sub m}) around 1.05, alumina-sulfur ratio (P) around 2.5, alumina-silica ratio (N) around 2.0{approx}3.0 and firing the raw mixes at 1250 deg. C for 2 h. The compressive strengths of SAC are high in early age while that develop slowly in later age. Results also show that the expansive properties of SAC are strongly depended on the gypsum content. Leaching studies of toxic elements in the hydrated SAC-based system reveal that all the investigated elements are well bounded in the clinker minerals or immobilized by the hydration products. Although some limited positive results indicate that the SAC prepared from MSWI fly ash would present no immediate thread to the environment, the long-term toxicity leaching behavior needs to be further studied.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2013

ASME AG-1 Section FC Qualified HEPA Filters; a Particle Loading Comparison - 13435

High Efficiency Particulate Air (HEPA) Filters used to protect personnel, the public and the environment from airborne radioactive materials are designed, manufactured and qualified in accordance with ASME AG-1 Code section FC (HEPA Filters) [1]. The qualification process requires that filters manufactured in accordance with this ASME AG-1 code section must meet several performance requirements. These requirements include performance specifications for resistance to airflow, aerosol penetration, resistance to rough handling, resistance to pressure (includes high humidity and water droplet exposure), resistance to heated air, spot flame resistance and a visual/dimensional inspection. None of these requirements evaluate the particle loading capacity of a HEPA filter design. Concerns, over the particle loading capacity, of the different designs included within the ASME AG-1 section FC code[1], have been voiced in the recent past. Additionally, the ability of a filter to maintain its integrity, if subjected to severe operating conditions such as elevated relative humidity, fog conditions or elevated temperature, after loading in use over long service intervals is also a major concern. Although currently qualified HEPA filter media are likely to have similar loading characteristics when evaluated independently, filter pleat geometry can have a significant impact on the in-situ particle loading capacity of filter packs. Aerosol particle characteristics, such as size and composition, may also have a significant impact on filter loading capacity. Test results comparing filter loading capacities for three different aerosol particles and three different filter pack configurations are reviewed. The information presented represents an empirical performance comparison among the filter designs tested. The results may serve as a basis for further discussion toward the possible development of a particle loading test to be included in the qualification requirements of ASME AG-1 Code sections FC and FK[1]. (authors)

42 ENGINEERING↗

NASA NTRS2021

Thunderstorm and Fair-weather Quasi-Static Electric Fields Over Land and Ocean

Natural lightning and the associated clouds are known to behave differently over land and ocean, but many questions remain. We expand the related observational datasets by obtaining simultaneous quasi-static electric field observations over coastal land, near-shore water, and deep ocean regions during both fair-weather and thunderstorm periods. Oceanic observations were obtained using two 3-m NOAA buoys that were instrumented with Campbell Scientific electric field mills to measure the quasi-static electric fields. These data were compared to selected electric field records from the existing on-shore electric field mill suite of 31 sensors at Kennedy Space Center (KSC). Lightning occurrence times, locations and peak current estimates for both onshore and ocean were provided by the U.S. National Lightning Detection Network. The buoy instruments were first evaluated on-shore at the Florida coast, and the first system was calibrated for field enhancements and to confirm proper behavior of the system in elevated-field environments. The buoys were then moored 20 mi and 120 mi off the coast of KSC in February (20 mi) and August (120 mi) 2014. Diurnal fair-weather fields at both ocean sites matched will with each other and with those found during the Carnegie cruise, but mean values were 33% smaller, due at least in-part to constraints on the calibration procedure. Diurnal fair-weather fields variations at coastal and inland sites were a poorer match than offshore, likely because the offshore environment is “cleaner” with limited variations in local space charge, lower surface aerosol densities, little surface heating to disturb the surface charge layer during fair weather, and fewer local radioactive sources to modulate the near-surface electrical conductivity. Storm-related static fields were 4-5× larger at both oceanic sites than over land, likely due to decreased screening by near-surface space charge produced by corona current. The time-evolution of the electric field and field changes during storm approach are sufficiently different over land and ocean to warrant further study. This work shows the quality, accuracy, and reliability of these data, and has demonstrated the practicality of off-shore electric field measurements for safety- and launch-related decision making at KSC.

Lightning↗

DOE OSTI2018

Testing of an Integrated Nitrogen Oxide Catcher

A gas-purification system with maximum capacity 50 m{sup 3}/h was developed, fabricated, and tested to catch nitrogen oxides released during hydrometallurgical processing of spent fuel from the BREST reactor. To catch nitrogen oxides, the setup employs water aerosols introduced into the gas duct; it also includes a tank for mixing water aerosols with gas flow, coarse and fine filters, and BRUNS and SMOG apparatus. The filtering complex (mixing tank, FCGO and FAROS filters) gave 72–76% conversion of nitrogen dioxide with initial concentration of 11 g/m{sup 3}; this confirmed that aerosol fiberglass filters can be used to catch nitrogen dioxide. In the tests, the complex of units comprising the setup gave 95.4–98.5% conversion of nitrogen oxide with initial concentration 11–50 g/m{sup 3}. After the design of the mixing tanks is improved and remote extraction of the cartridges of the gas purification apparatus is organized, the tested gas purification setup can be used in radiochemical production.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2026

Statistical Uncertainty of Inhalation Dose Coefficients: Impact of Particle Deposition in ICRP 66 Human Respiratory Tract Model

Inhaled radioactive materials can pose a long-term health concern, as the material can be incorporated into the body’s metabolic pathways and remain in organs and tissues for extended durations. During the retention period, the radioactive material may localize in a source organ and irradiate adjacent target organs and tissues. Distribution of these materials changes over time, requiring biokinetic modeling to evaluate their movement through various tissues and organs. The evolving distribution depends on multiple inputs characterizing the inhaled material, such as particle size and size distribution, particle density, aspect ratio, specific radionuclide, the chemical form, and solubility. In addition, biological parameters such as breathing rate, breathing type (nasal or nasal/oral), respiratory system morphometry, tidal volume, functional residual capacity, and anatomical dead space all influence material transport. These aerosol properties and physiological characteristics of the respiratory tract jointly define a range of initial conditions that influence the time-dependent distribution of radioactive material. To evaluate both uncertainty in the initial conditions of inhalation exposure and the final output (committed effective dose) from biokinetic models, a Python-based software tool, Radiological Exposure Dose Calculator (REDCAL), was developed to propagate uncertainty within the human respiratory tract model. Focusing on deposition fraction uncertainty, the primary objective was to characterize the initial activity distribution across respiratory regions as a function of anticipated particle sizes and distributions. The impact of the deposition fraction uncertainty was propagated to committed effective dose coefficients for selected radionuclides in a companion publication. For each particle size, a lognormal distribution, characterized by its geometric mean as defined within ICRP Publication 66, serves as the basis for introducing uncertainty into the physical processes governing deposition in various lung regions. Finally, this study addresses the deposition process and examines how uncertainty in deposition mechanisms affects activity distribution in the airways, ultimately presenting the expected range and standard deviation of deposited activity as a function of particle size.

International Commission on Radiological Protectio↗