Methods and instrumentation for monitoring radioactive contamination
Radioactive contamination monitoring methods and instrumentation
Fey, F. L., Jr.↗
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Effects of the space environment on space-based radar phased-array antenna; status and preliminary observations (LDEF Experiment A0133)
The overall objective of the experiment was to evaluate the effect of the space environment on components considered for a Space-Based Radar (SBR) Phased-Array Antenna. Of primary interest was a study of the degradation of the polyimide film Kapton (DuPont trademark), the material considered for use in the antenna plane. The most striking result of the experiment was the overall good condition of the Kapton antenna planes and Kapton tensile specimens, despite nearly six years of exposure to the space environment. This was largely attributable to the orientation of the Kapton (parallel and flush on the space end) and the stability of the Long Duration Exposure Facility (LDEF) in orbit. However, weathering of exposed Kapton surfaces was not insignificant. Results on elongation and mechanical properties of the plain and the fiberglass-reinforced Kapton are presented. Reduction in strain to failure of flight-exposed Kapton is attributed to surface defects of these specimens. Physical property testing of the materials to date reveals no significant difference between flight-exposed and control material. The second objective was to investigate the interaction between high-voltage electrodes and typical spacecraft contaminants in simulation of discharge triggering across differentially charged dielectric surfaces (spacecraft charging conditions). Electronic data acquisition and memory systems appeared to operate correctly, but very few discharges were recorded. Induced radioactivity, contamination, impacts, and orientation features of atomic oxygen erosion were observed.
J B Whiteside↗
Retrospective dosimetry related to chronic environmental exposure
Radioactive contamination of the environment occurred in the early fifties as a result of the releases from the Mayak plutonium production complex (Southern Urals, Russia). The releases of liquid wastes into the Techa river resulted in chronic exposure of 30,000 residents of the riverside communities. Since 1951 90Sr body burdens have been measured for over half of this cohort. This paper presents the analysis of data on 90Sr in humans and describes the reconstruction of internal doses for these people.
NASA Discipline Radiation Health↗
New shield for gamma-ray spectrometry
Gamma-ray shield that can be evacuated, refilled with a clean gas, and pressurized for exclusion of airborne radioactive contaminants effectively lowers background noise. Under working conditions, repeated evacuation and filling procedures have not adversely affected the sensitivity and resolution of the crystal detector.
Brar, S. S.↗
Isotope alpha irradiators for radiobiological research
Radiation absorption is considered for the case where the isotopic alpha source, in the form of a flat disk, and the axially located biological object, also in the form of a flat disk, are separated by a layer of gas. Frequently the biological object is covered by a polymer film with minimal thickness for protection against radioactive contaminants. The energy of the alpha particle is calculated at the place where the absorbed dose is determined, taking into account loss of energy in air, film and tissue. The level of energy is determined by the specific loss in energy of the alpha particle arriving from the point source to a point at the biological subject.
Drasher, V.↗
Viewer Makes Radioactivity "Visible"
Battery operated viewer demonstrates feasibility of generating threedimensional visible light simulations of objects that emit X-ray or gamma rays. Ray paths are traced for two pinhold positions to show location of reconstructed image. Images formed by pinholes are converted to intensified visible-light images. Applications range from radioactivity contamination surveys to monitoring radioisotope absorption in tumors.
Yin, L. I.↗
Snowballs in Euclid and WFIRST Detectors
Snowballs are transient events observed in HgCdTe detectors with a sudden increase of charge in a few pixels. They appear between consecutive reads of the detector, after which the affected pixels return to their normal behavior. The origin of the snowballs is unknown, but it was speculated that they could be the result of alpha decay of naturally radioactive contaminants in the detectors, but a cosmic ray origin cannot be ruled out. Even though previous studies predicted a low rate of occurrence of these events, and consequently, a minimal impact on science, it is interesting to investigate the cause or causes that may generate snowballs and their impact in detectors designed for future missions. We searched for the presence of snowballs in the dark current data in Euclid and Wide Field Infrared Survey Telescope (WFIRST) detectors tested in the Detector Characterization Laboratory at Goddard Space Flight Center. Our investigation shows that for Euclid and WFIRST detectors, there are snowballs that appear only one time, and others that repeat in the same spatial localization. For Euclid detectors, there is a correlation between the snowballs that repeat and bad pixels in the operational masks (pixels that do not fulfill the requirements to pass spectroscopy noise, photometry noise, quantum efficiency, and/or linearity). The rate of occurrence for a snowball event is about 0.9 snowballs/hr. in Euclid detectors (for the ones that do not have associated bad pixels in the mask), and about 0.7 snowballs/hr. in PV3 Full Array Lot WFIRST detectors.
Astronomy↗
Radioactive tracer system detects oil contaminants in fluid lines
Radioactive tracer system continuously detects and monitors lubricating oil contamination in high pressure fluid lines.
Roth, B.↗
Ion engine supporting research and evaluation. Volume II - Ionization studies Summary report
Ionization studies dealing with ion source, emission contamination, and alkali desorption energies on polycrystalline refractory metals
REFRACTORY METAL↗
Shear stress cleaning for surface departiculation
A cleaning technique widely used by the nuclear utility industry for removal of radioactive surface contamination has proven effective at removing non-hazardous contaminant particles as small as 0.1 micrometer. The process employs a controlled high velocity liquid spray inside a vapor containment enclosure to remove particles from a surface. The viscous drag force generated by the cleaning fluid applies a shear stress greater than the adhesion force that holds small particles to a substrate. Fluid mechanics and field tests indicate general cleaning parameters.
Musselman, R. P.↗
Development and demonstration of a telerobotic excavation system
Oak Ridge National Laboratory is developing remote excavation technologies for the Department of Energy's Office (DOE) of Technology Development, Robotics Technology Development Program, and also for the Department of Defense (DOD) Project Manager for Ammunition Logistics. This work is being done to meet the need for remote excavation and removal of radioactive and contaminated buried waste at several DOE sites and unexploded ordnance at DOD sites. System requirements are based on the need to uncover and remove waste from burial sites in a way that does not cause unnecessary personnel exposure or additional environmental contamination. Goals for the current project are to demonstrate dexterous control of a backhoe with force feedback and to implement robotic operations that will improve productivity. The Telerobotic Small Emplacement Excavator is a prototype system that incorporates the needed robotic and telerobotic capabilities on a commercially available platform. The ability to add remote dexterous teleoperation and robotic operating modes is intended to be adaptable to other commercially available excavator systems.
Burks, Barry L.↗
Atomic energy commission high altitude sampling systems
High altitude sampling systems - balloon and rocketborne samplers for collection of radioactive particles and gaseous contaminants
SAMPLING DEVICE↗
Chemical evolution of OB associations
It is determined that the existence of Al-26 and Pd-107 in meteorites in the early solar system indicates that our solar system probably formed inside an OB association that had been contaminated by the debris of at least one supernova. In addition to these radioactive tracers, the contamination of the material out of which the solar system formed would have significantly enriched the heavy element composition of the solar system relative to that of the average interstellar medium. It is found that the solar system would be enriched in those isotopes which are produced by the more massive stars, such as O-16, C-12, Ne-20, and some other r-process material. It is proposed that specific isotopic ratios and elemental ratios reflecting these differences would include the Ne-20/Ne-22 ratio, which would be higher in the solar system than in the interstellar medium and the cosmic rays, the C-12/C-13 ratio which would be higher in the solar system than in the interstellar medium, and the oxygen-to-carbon ratio, which would also be higher in the solar system than in the typical interstellar medium.
Schramm, D. N.↗
Study of extraterrestrial disposal of radioactive wastes. Part 3: Preliminary feasibility screening study of space disposal of the actinide radioactive wastes with 1 percent and 0.1 percent fission product contamination
A preliminary study was conducted of the feasibility of space disposal of the actinide class of radioactive waste material. This waste was assumed to contain 1 and 0.1 percent residual fission products, since it may not be feasible to completely separate the actinides. The actinides are a small fraction of the total waste but they remain radioactive much longer than the other wastes and must be isolated from human encounter for tens of thousands of years. Results indicate that space disposal is promising but more study is required, particularly in the area of safety. The minimum cost of space transportation would increase the consumer electric utility bill by the order of 1 percent for earth escape and 3 percent for solar escape. The waste package in this phase of the study was designed for normal operating conditions only; the design of next phase of the study will include provisions for accident safety. The number of shuttle launches per year required to dispose of all U.S. generated actinide waste with 0.1 percent residual fission products varies between 3 and 15 in 1985 and between 25 and 110 by 2000. The lower values assume earth escape (solar orbit) and the higher values are for escape from the solar system.
Hyland, R. E.↗
Studies on the Mechanisms of Microbial Adaptation to the Physical Environment
The environmental factors which affect humans and other animals also influence the microorganisms which are such an important part of our ecology. Some of the microorganisms are very closely associated with animals, living in the digestive tract and synthesizing essential nutrients for the host. For these microbes, most external physical changes are of little consequence, because they are well shielded by the animals' homeostatic systems. The vast majority of microorganisms, however, live free in nature, especially in the soil and oceans. It has been estimated that the upper 15 cm of a fertile soil may contain over 4000 kg of bacteria and fungi per hectare. These organisms are responsible for degrading the complex molecules of plants and animals when they die, eventually producing simple organics, carbon dioxide, and inorganics, which are then used for the next cycle of plant growth. It is believed that over 90 % of the biologically produced carbon dioxide results from the metabolic activity of bacteria and fungi. In addition to recycling plant nutrients, soil bacteria also provide new nutrients through 'fixation' of atmospheric nitrogen into ammonia and nitrate, the forms which can be used by plants. Microorganisms so have an enormous capacity for detoxifying both natural and man-made poisons. All of these functions of microorganisms are essential to the operation of the material cycles on Earth. This is true of all locations on the planet, regardless of the climate or other environmental factors. In fact, one of the most impressive attributes of microorganisms is their ability to adapt to every stable environment on Earth. These include such extremes as polar regions, hot springs, water saturated with salt, mountain tops, ocean depths, acid and alkaline waters, deserts, intense radioactivity, soil and water contaminated with toxic chemicals or petroleum, and areas devoid of oxygen.
Heinrich, M. R.↗
Explosion Welding for Hermetic Containerization
A container designed for storing samples of hazardous material features a double wall, part of which is sacrificed during an explosion-welding process in which the container is sealed and transferred to a clean environment. The major advantage of this container sealing process is that once the samples have been sealed inside, the outer wall of what remains of the container is a clean surface that has not come into contact with the environment from which the samples were taken. Thus, there is no need to devise a decontamination process capable of mitigating all hazards that might be posed by unanticipated radioactive, chemical, and/or biological contamination of the outside of the container. The container sealing method was originally intended to be used to return samples from Mars to Earth, but it could also be used to store samples of hazardous materials, without the need to decontaminate its outer surface. The process stages are shown. In its initial double-wall form, the volume between the walls is isolated from the environment; in other words, the outer wall (which is later sacrificed) initially serves to protect the inner container from contamination. The sample is placed inside the container through an opening at one end, then the container is placed into a transfer dock/lid. The surfaces that will be welded together under the explosive have been coated with a soft metallic sacrificial layer. During the explosion, the sacrificial layer is ejected, and the container walls are welded together, creating a strong metallic seal. The inner container is released during the same event and enters the clean environment.
Dolgin, Benjamin↗
Measurements with the Chandra Flight Contamination Monitor
NASA's Chandra X-ray Observatory includes a Flight Contamination Monitor (FCM), a system of 16 radioactive calibration sources mounted to the inside of the Observatory's forward contamination cover. The purpose of the FCM is to verify the ground-to-orbit transfer of the Chandra flux scale, through comparison of data acquired during the ground calibration with those obtained in orbit, immediately prior to opening the Observatory's sun-shade door. Here we report results of these measurements, which place limits on the change in mirror-detector system response and, hence, on any accumulation of molecular contamination on the mirrors' iridium-coated surfaces.
Elsner, R. E.↗
Measurements with the Chandra X-ray Observatory's Flight Contamination Monitor
NASA's Chandra X-ray Observatory includes a Flight Contamination Monitor (FCM), a system of 16 radioactive calibration sources mounted to the inside of the Observatory's forward contamination cover. The purpose of the FCM is to verify the ground-to-orbit transfer of the Chandra flux scale, through comparison of data acquired during the ground calibration with those obtained in orbit, immediately prior to opening the Observatory's sun-shade door. Here we report results of these measurements., which place limits on the change in the mirror-detector system response and, hence, on any accumulation of molecular contamination on the mirrors' iridium-coated surfaces between the two sets of measurements.
Elsner, R. F.↗