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The contamination control activity performed for the Cassini Imaging Science Subsystem (ISS) consisted of an overall analysis for susceptibility to molecular and particulate contamination at the sensor's most sensitive wavelengths.
NASA is committed to landing the first woman and first person of color on the Moon by 2025 to begin a sustaining presence. A major component of this mission is NASA’s orbiting lunar outpost, Gateway, that will be subjected to the harsh environment of space during its 7-day orbit around the Moon. One aspect of this environment that is not well quantified is microscopic lunar regolith particles, or simply, lunar dust. As Apollo 17 Mission Commander Eugene Cernan said, “I think dust is probably one of our greatest inhibitors to a nominal operation on the moon. I think we can overcome other physiological or physical or mechanical problems except dust” [1]. These dust particles, most of which are smaller than the width of two human hairs and of highly irregular shape, are composed mainly of dielectric materials. Such characteristics can allow the dust particles to collect electric charge from the surrounding environment, resulting in electrostatic interactions between the dust, electromagnetic fields, and electrically charged surfaces [2-3]. Due to the nature of these fields, dust can collect on and contaminate charged surfaces. Lunar dust introduced into the Gateway environment by a lunar ascent vehicle element returning from the surface of the Moon presents risks to Gateway hardware such as radiators, solar arrays, antennae, and docking mechanisms. To quantify this risk and inform NASA, International Partner, and Commercial Provider stakeholders, Booz Allen, in partnership with NASA, is developing a toolset to model the interaction of charged lunar dust particles with the cis-lunar and deep-space environments. This includes a comprehensive physics model of the space plasma and solar radiation environment and electromagnetic interaction of spacecraft and lunar dust. Spacecraft charging and plasma environment are solved using the open-source code from The French Aerospace Lab (ONERA) and the European Space Agency (ESA), known as Spacecraft Plasma Interaction Software (SPIS) [4]. The physics of particle charging and motion is handled by a time-dependent implementation of Orbital-Motion-Limited (OML) theory which accounts for plasma flows and positive potential grains [5-7], using Siemens STAR-CCM+ as the framework. Model validation includes lab experiments by NASA experts and academia, as well as future on-orbit dust detecting payloads on the exterior of Gateway and Commercial Lunar Payload Services (CLPS) missions to the lunar surface [7-9]. The results and analyses will inform Gateway Program system owners at risk for lunar dust contamination.
This paper summarizes a recent numerical analysis of water vapor and volatile condensible material deposition on the James Webb Space Telescope from the initial orbit insertion up to 180 days post launch. The analysis utilized 17 distinct geometry files capturing observatory configuration changes during the deployment. Surface temperature was set from a time-dependent thermal analysis solution. A vapor pressure model was used to calculate the net water ice adsorption. Molecular contamination included a contribution from UV photopolymerization. The analysis predicted levels of ice and molecular accumulation were found to be within the allowable limits specified by the observatory contamination control plan.
In preparation for the James Webb Space Telescope (JWST) launch at Centre Spatial Guyanias (CSG) in French Guiana, particulate contamination accumulation predictions were necessary for each facility in which the hardware would be exposed because the Telescope would be uncovered in each of the facilities and had strict particulate requirements. These included facilities for final integration and testing, fueling, transportation and encapsulation. Minimal heritage data existed from CSG and previous launch campaigns to use as a basis for contamination predictions. Data from the Automatic Transfer Vehicle and Herschel & Planck launch campaigns were used in conjunction with facility monitoring data provided by ESA and data collected during JWST working group visits to CSG. These campaigns were conducted at varying cleanliness levels that were typically less stringent than JWST requirements. Each facility was evaluated using the data provided and likely performance improvement with the addition of High Efficiency Particulate Air filter (HEPA) banks operating when possible. Once the launch campaign was completed, the predicted fallout was compared with actual data collected throughout the campaign. Based on the actual measurements, JWST’s primary and secondary mirrors turned out to be much cleaner than what was predicted.
This paper summarizes a recent numerical analysis of water vapor and volatile condensible material deposition on the James Webb Space Telescope from the initial orbit insertion up to 180 days post launch. The analysis utilized 17 distinct geometry files capturing observatory configuration changes during the deployment. Surface temperature was set from a time-dependent thermal analysis solution. A vapor pressure model was used to calculate the net water ice adsorption. Molecular contamination included a contribution from UV photopolymerization. The analysis predicted levels of ice and molecular accumulation were found to be within the allowable limits specified by the observatory contamination control plan.
"In preparation for the James Webb Space Telescope (JWST) launch at Centre Spatial Guyanias (CSG) in French Guiana, particulate contamination accumulation predictions were necessary for each facility in which the hardware would be exposed because the Telescope would be uncovered in each of the facilities and had strict particulate requirements. These included facilities for final integration and testing, fueling, transportation and encapsulation. Minimal heritage data existed from CSG and previous launch campaigns to use as a basis for contamination predictions. Data from the Automatic Transfer Vehicle and Herschel & Planck launch campaigns were used in conjunction with facility monitoring data provided by ESA and data collected during JWST working group visits to CSG. These campaigns were conducted at varying cleanliness levels that were typically less stringent than JWST requirements. Each facility was evaluated using the data provided and likely performance improvement with the addition of High Efficiency Particulate Air filter (HEPA) banks operating when possible. Once the launch campaign was completed, the predicted fallout was compared with actual data collected throughout the campaign. Based on the actual measurements, JWST’s primary and secondary mirrors are likely much cleaner than was expected with the predicted fallout in each facility. "
The James Webb Space Telescope (JWST) has actively been in process since 1996, and at last, on Christmas Day 2021, it launched. This launch was the fulfillment of an astounding level of work performed by thousands of people across the globe in dozens of disciplines. From the start, effective contamination control was considered essential for the JWST mission due to the large, exposed optics and tight sensitivity required to measure first light and faint signals at the dawn of the universe. This paper will present the JWST mission and requirements overview, including mission requirements that led to optimizing performance for collecting light in the Near Infrared (NIR, 0.6μm) – Mid Infrared (MIR, 29μm) range. Molecular films absorb in the IR bands and can alter thermal emissivity, resulting in increased noise at the longer wavelengths (MIRI). Particles increase light scatter and background noise levels at the shorter wavelengths (NIRSpec, NIRCam and FGS). The passively cooled design of JWST led to an open architecture for the optical telescope element (OTE), presenting the challenge of maintaining cleanliness throughout assembly, integration, and test in a multitude of environments. The paper will describe the mission and will introduce the specific areas of contamination control developed and advanced to keep JWST clean at an unsurpassed level of cleanliness.
The OSIRIS-REx mission to asteroid Bennu successfully collected hundreds of grams of asteroid regolith in October 2020 [1]. The spacecraft departed Bennu in May 2021 for Earth return and will release the sample canister to be recovered in Utah in September 2023 [2]. Samples will be transported to the curation facility at NASA Johnson Space Center, where an ISO5 equivalent cleanroom has been designed in 2017 and completed in 2021. Aspects of the design and material selection for the cleanroom and its supporting facilities (air handling system, cleanroom floors and walls, filters, paints, etc.) were optimized to minimize effects of organic and inorganic contaminants and offgassing [3]. Since its completion, the lab has been carefully monitored to understand and establish a baseline with respect to multiple environmental aspects – measurement of particle counts, deploying Si wafer witness plates for organic and inorganic contaminants, deploying aluminum foils for a focus on organics with JSC in-house expertise, gas samples, and regular microbial and fungal measurements on selected surfaces and air samples in the cleanroom. This contribution will report on nearly one year of monitoring and highlight several specific aspects that have led to a better understanding of the new cleanroom environment.
The James Webb Space Telescope (JWST) has actively been in process since 1996, and at last, on Christmas Day 2021, it launched. This launch was the fulfillment of an astounding level of work performed by thousands of people across the globe in dozens of disciplines. From the start, effective contamination control (CC) was considered essential for the JWST mission due to the large, exposed optics and tight sensitivity required to measure first light and faint signals at the dawn of the universe. This presentation will present the JWST mission and requirements overview, including mission requirements that led to optimizing performance for collecting light in the Near Infrared (NIR, 0.6μm) – Mid Infrared (MIR, 29μm) range. Molecular films absorb in the IR bands and can alter thermal emissivity, resulting in increased noise at the longer wavelengths (MIRI). Particles increase light scatter and background noise levels at the shorter wavelengths (NIRSpec, NIRCam and FGS). The passively cooled design of JWST led to an open architecture for the optical telescope element (OTE), presenting the challenge of maintaining cleanliness throughout assembly, integration, and test in a multitude of environments for over 2 decades. The presentation will describe CC for the mission starting with the first architecture in 1996, then introducing the specific areas of contamination control developed and advanced to keep JWST clean at an unsurpassed level of cleanliness.
The Array Collectors of the Genesis spacecraft collected bulk solar wind (SW), as well as three subsets of SW (fast, slow, and coronal mass ejection) in a variety of materials. In all cases the SW implant peaked within < 0.2 microns of the surface. So, when the sample return capsule crashed on landing, cleaning the surfaces for analysis became an extremely difficult, but imperative, task. One collector material was “sapphire”, commercial single crystal corundum. Only ~7.7% of the Genesis Array collectors were sapphire (SAP) but a much higher percentage survived the crash. In fact, surviving bulk SW sapphire collectors have an average area ~10x that of their silicon counterparts since SAP is physically tough, and hard (MOHS 9, by definition) as well as is chemically inert. So, SAP is a good candidate for analytical techniques for measuring SW that require clean areas larger than a millimeter; e.g., synchrotron TXRF and INAA. It is also possible to measure SW in SAP using laser ablation and secondary ion mass spectrometry (SIMS) and, recently, more researchers are choosing to analyze sapphire. Thus, removing surface contamination from SAP could enable many research projects. This report extends the task presented in Schmeling et al. ([4]) that used polishing compounds to remove contamination from Genesis sapphire. It focuses on how polishing with their two top candidates (colloidal silica and cerium oxide) affects the SW layer in SAP.
Crystalline Silico-Titanates (CSTs) are synthetic zeolites designed by Sandia National Laboratories scientists to selectively capture radioactive cesium and other group I metals. They are being used for cleanup of radiation-contaminated water at the Fukushima Daiichi nuclear power plant in Japan. Quick action by Sandia and its corporate partner UOP, A Honeywell Company, led to rapid licensing and deployment of the technology in Japan, where it continues to be used to clean up cesium contaminated water at the Fukushima power plant.
Idaho National Laboratory’s FX2 fixative solution was deployed as part of the decontamination and decommissioning (D&D) of an alpha-contaminated glovebox. The fixative was dispensed via fogging. The goal of the deployment was to reduce friable alpha radioactive contamination prior to removal of the glovebox. Information about the deployment and the efficacy of the treatment is presented.
This manuscript presents an assessment of the electrothermal instability (ETI) in the presence of anomalous resistivity (AR) in vacuum contaminant plasmas (VCP) when applied to a magnetized liner inertial fusion (MagLIF)-like load.Pulsed-power driven dielectrically coated metallic liners, like in MagLIF, experience the current-driven electrothermal instability which occurs when a material’s resistivity changes with temperature and is subject to ohmic heating. Large scale pulsed-power facilities that use magnetically insulated transmission lines (MITL) have been shown to generate low-density plasma which enters the target chamber and coalesces around the load. The low-density high-temperature vacuum contaminant plasmas (VCP) can parasitically divert current from the load through causing a short in the anode-cathode gap inside the target chamber. Resistive magnetohydrodynamic (MHD) simulations of these VCP experience unphysical runaway ohmic heating due to under predicting the resistivity by using a purely collisional resistivity model.AR provides a physics-based way to address this runaway heating through increasing the resistivity in a proportional way with the drift speed. In this work, 1D simulations probe the effect that AR in VCP has on the magnetic diffusion rate, and 2D simulations show how this effect manifests in the nonlinear striation form of the ETI for a MagLIF-like load. Beryllium and aluminum dielectrically coated liners are used for the 1D and 2D simulations in this work. The1D simulations show that a VCP causes a delay in the current delivery to the load by upwards of 8 ns at 60 ns into atypical current pulse for an 1 × 10 7 A scale pulsed-power accelerator. The 2D simulations show the delay observed in the 1D simulations is reduced substantially (4 ns) by 2D turbulence that disrupts the VCP layer early in time. Here, the 2Dsimulated ETI growth varies across AR models, more so for the beryllium liner than the aluminum liner because the beryllium liner shows an enhanced rate of penetration for the magnetic diffusion wave in comparison to the aluminum liner. The 2D simulations show the bulk dielectric thickness varies across AR models with the Davidson AR model beingthe largest and the Buneman AR model being the smallest, and in connection with the thickness the Rayleigh-Taylor bubble-spike distances varies correspondingly.
The goal of United States (U.S.) Department of Energy's (DOE)'s environmental remediation programs is to restore groundwater to beneficial use, similar to many other Federal and state environmental cleanup programs. Based on past experience, groundwater remediation to pre-contamination conditions (i.e., drinking water standards or non-detectable concentrations) can be successfully achieved at many sites. At a subset of the most complex sites, however, complete restoration is not likely achievable within the next 50 to 100 years using today's technology. This presentation describes several approaches used at complex sites in the face of these technical challenges. Many complex sites adopted a long-term management approach, whereby contamination was contained within a specified area using active or passive remediation techniques. Consistent with the requirements of their respective environmental cleanup programs, several complex sites selected land use restrictions and used risk management approaches to accordingly adopt alternative cleanup goals (alternative endpoints). Several sites used long-term management designations and approaches in conjunction with the alternative endpoints. Examples include various state designations for groundwater management zones, technical impracticability (TI) waivers or greater risk waivers at Superfund sites, and the use of Monitored Natural Attenuation (MNA) or other passive long-term management approaches over long time frames. This presentation will focus on findings, statistics, and case studies from a recently-completed report for the Department of Defense's Environmental Security Technology Certification Program (ESTCP) (Project ER-0832) on alternative endpoints and approaches for groundwater remediation at complex sites under a variety of Federal and state cleanup programs. The primary objective of the project was to provide environmental managers and regulators with tools, metrics, and information needed to evaluate alternative endpoints for groundwater remediation at complex sites. A statistical analysis of Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) sites receiving TI waivers will be presented as well as case studies of other types of alternative endpoints and alternative remedial strategies that illustrate the variety of approaches used at complex sites and the technical analyses used to predict and document cost, time frame, and potential remedial effectiveness. This presentation is intended to inform DOE program managers, state regulators, practitioners and other stakeholders who are evaluating technical cleanup challenges within their own programs, and establishing programmatic approaches to evaluating and implementing long-term management approaches. Case studies provide examples of long-term management designations and strategies to manage and remediate groundwater at complex sites. At least 13 states consider some designation for groundwater containment in their corrective action policies, such as groundwater management zones, containment zones, and groundwater classification exemption areas. Long-term management designations are not a way to 'do nothing' or walk away from a site. Instead, soil and groundwater within the zone is managed to be protective of human health and the environment. Understanding when and how to adopt a long-term management approach can lead to cost savings and the more efficient use of resources across DOE and at numerous other industrial and military sites across the U.S. This presentation provides context for assessing the use and appropriate role of alternative endpoints and supporting long-term management designations in final remedies. (authors)
Department of Energy (DOE) requirements for the release of non-real property, including solid waste, containing low levels of residual radioactive materials are specified in DOE Order 458.1 and associated guidance. Authorized limits have been approved under the requirements of DOE Order 5400.5, predecessor to DOE Order 458.1, to permit disposal of solid waste containing low levels of residual radioactive materials at solid waste landfills located within the DOE Oak Ridge Reservation (ORR). Specifically, volumetric concentration limits for disposal of solid waste at Industrial Landfill V and at Construction/Demolition Landfill VII were established in 2003 and 2007, respectively, based on the requirements in effect at that time, which included: an evaluation to ensure that radiation doses to the public would not exceed 25 mrem/year and would be as low as reasonably achievable (ALARA), with a goal of a few mrem/year or less (in fact, these authorized limits actually were derived to meet a dose constraint of 1 mrem/year); an evaluation of compliance with groundwater protection requirements; and reasonable assurance that the proposed disposal is not likely to result in a future requirement for remediation of the landfill. Prior to approval as DOE authorized limits, these volumetric concentration limits were coordinated with the Tennessee Department of Environment and Conservation (TDEC) and documented in a Memorandum of Understanding (MOU) between the TDEC Division of Radiological Health and the TDEC Division of Solid Waste Management. These limits apply to the disposal of soil and debris waste generated from construction, maintenance, environmental restoration, and decontamination and decommissioning (D and D) activities on the DOE Oak Ridge Reservation. The approved site-specific authorized limits were incorporated in the URS/CH2M Oak Ridge LLC (UCOR) waste profile system that authorizes disposal of special wastes at either of the RCRA Subtitle D landfills. However, a recent DOE assessment found that implementation of the site-specific authorized limits for volumetrically contaminated waste was potentially limited due in part to confusion regarding the applicability of volumetric concentration limits and/or surface activity limits to specific wastes. This paper describes recent efforts to update the authorized limits for Industrial Landfill V and Construction/Demolition Landfill VII and to improve the procedures for implementation of these criteria. The approved authorized limits have been evaluated and confirmed to meet the current requirements of DOE Order 458.1, which superseded DOE Order 5400.5 in February 2011. In addition, volumetric concentration limits have been developed for additional radionuclides, and site-specific authorized limits for wastes with surface contamination have been developed. Implementing procedures have been revised to clarify the applicability of volumetric concentration limits and surface activity limits, and to allow the use of non-destructive waste characterization methods. These changes have been designed to promote improved utilization of available disposal capacity of the onsite disposal facilities within the DOE Oak Ridge Reservation. In addition, these changes serve to bring the waste acceptance requirements at these DOE onsite landfills into greater consistency with the requirements for commercial/ public landfills under the TDEC Bulk Survey for Release (BSFR) program, including two public RCRA Subtitle D landfills in close proximity to the DOE Oak Ridge Reservation. (authors)
The U.S. Environmental Protection Agency (EPA) Superfund program is developing a new Counts Per Minute (CPM) calculator to correlate real-time survey results, which are often expressed as counts per minute, to contaminant concentrations that are more typically provided in risk assessments or for cleanup levels, usually expressed in pCi/g or pCi/m{sup 2}. Currently there is no EPA guidance for Superfund sites on correlating count per minute field survey readings back to risk, dose, or other ARAR based concentrations. The CPM calculator is a web-based model that estimates a gamma detector response for a given level of contamination. The intent of the CPM calculator is to facilitate more real-time measurements within a Superfund response framework. The draft of the CPM calculator is still undergoing internal EPA review. This will be followed by external peer review. It is expected that the CPM calculator will at least be in peer review by the time of WM2012 and possibly finalized at that time. The CPM calculator should facilitate greater use of real-time measurement at Superfund sites. The CPM calculator may also standardize the process of converting lab data to real time measurements. It will thus lessen the amount of lab sampling that is needed for site characterization and confirmation surveys, but it will not remove the need for sampling. (authors)
Estimates as well as subsequent measurements of the radiation released following the events at the Fukushima Daiichi Nuclear Power Plant in March 2011 place the incident as the second greatest nuclear event to have ever occurred - duly rated at the maximum of Level 7 on the INES Event Scale. The releases of radioactivity from the plant were detected worldwide, however the multi-reactor nature of the events at the FDNPP has complicated the understanding of the radionuclide release inventory and the subsequent distribution of the material. As a result of this highly-complex release scenario, it is important to understand the current and evolving state of contamination within the rapidly evolving, topographically extreme and frequently typhoon impacted environment on Japan's eastern coast. Existing systems rely either on high-altitude manned aircraft to perform such contamination surveys, correcting results to ground-level, or, on humans manually measuring the dose-rate on foot. In order to overcome the shortcomings of both methods, a low-altitude unmanned aerial vehicle (UAV) has been developed at the University of Bristol and successfully deployed to the affected areas surrounding the FDNPP. In contrast to these other methods; the use of low-altitude UAVs provides a spatial resolution previously achievable only through the deployment of humans on the ground, with the potential for significant radiation exposure. This high-resolution monitoring allows for subsequent modelling to inform our understanding of the behaviour and long-term stability of the fallout material. (authors)
The Nuclear and Applied Robotics Group (NRG) has developed two mobile systems with simple, intuitive Human-Machine Interfaces (HMIs). Thus, the systems can be operated by operators who are not robotics experts to perform inventory, inspection and routine contamination surveys in areas where Special Nuclear Material (SNM) is stored and handled. This effort presents feedback collected from EM operators using the two systems at the Portsmouth Gaseous Diffusion Plant in Piketon, OH who used the robotic solutions to perform tasks on site and with minimal training. This approach has the potential to address issues related to ALARA, ergonomics, and reliably completing dull, repetitive tasks while maintaining domain-specific experts in the control loop. The two systems were shipped to - and demonstrated in - a DOE designated area and demonstrated completing contamination testing using a combination of real and surrogate sensors. This paper reviews the initial hardware development, demonstration requirements, and the modifications/improvements made to deploy the systems for this effort. It then summarizes the feedback garnered from EM operators who used the systems at the DOE facility. (authors)