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NASA NTRS2016

Thomas Leps Internship Abstract

An optical navigation system is being flown as the backup system to the primary Deep Space Network telemetry for navigation and guidance purposes on Orion. This is required to ensure Orion can recover from a loss of communication, which would simultaneously cause a loss of DSN telemetry. Images taken of the Moon and Earth are used to give range and position information to the navigation computer for trajectory calculations and maneuver execution. To get telemetry data from these images, the size and location of the moon need to be calculated with high accuracy and precision. The reentry envelope for the Orion EM-1 mission requires the centroid and radius of the moon images to be determined within 1/3 of a pixel 3 sigma. In order to ensure this accuracy and precision can be attained, I was tasked with building precise dot grid images for camera calibration as well as building a hardware in the loop test stand for flight software and hardware proofing. To calibrate the Op-Nav camera a dot grid is imaged with the camera, the error between the image dot location and the actual dot location can be used to build a distortion map of the camera and lens system so that images can be fixed to display truth locations. To build the dot grid images I used the Electro Optics Lab optical bench Bright Object Simulator System, and gimbal. The gimbal was slewed to a series of elevations and azimuths. An image of the collimated single point light source was then taken at each position. After a series of 99 images were taken at different locations the single light spots were extracted from each image and added to a composite image containing all 99 points. During the development of these grids it was noticed that an intermittent error in the artificial "star" locations occurred. Prior to the summer this error was attributed to the gimbal having glitches in it's pointing direction and was going to be replaced, however after further examining the issue I determined it to be a software issue. I have since narrowed the likely source of the error down to a Software Development Kit released by the camera supplier PixeLink. I have since developed a workaround in order to build star grids for calibration until the software bug can be isolated and fixed. I was also tasked with building a Hardware in the Loop test stand in order to test the full Op-Nav system. A 4k screen displays simulated Lunar and Terrestrial images from a possible Orion trajectory. These images are then projected through a collimator and then captured with an Op-Nav camera controlled by an Intel NUC computer running flight software. The flight software then analyzes the images to determine attitude and position, this data is then reconstructed into a trajectory and matched to the simulated trajectory in order to determine the accuracy of the attitude and position estimates. In order for the system to work it needs to be precisely and accurately aligned. I developed an alignment procedure that allows the screen, collimator and camera to be squared, centered and collinear with each other within a micron spatially and 5 arcseconds in rotation. I also designed a rigid mount for the screen that was machined on site in Building 10 by another intern. While I was working in the EOL we received a $500k Orion startracker for alignment procedure testing. Due to my prior experience in electronics development, as an ancillary duty, I was tasked with building the cables required to operate and power the startracker. If any errors are made building these cables the startracker would be destroyed, I was honored that the director of the lab entrusted such a critical component with me. This internship has cemented my view on public space exploration. I always preferred public sector to privatization because, as a scientist, the most interesting aspects of space for me are not necessarily the most profitable. I was concerned that the public sector was faltering however, and that in order to improve human space exploration I would be forced into private sector. I now know that, at least at JSC, human spaceflight is still progressing, and exciting work is still being done. I am now actively seeking employment at JSC after I complete my Ph.D and have met with my branch chiefs and mentor to discuss transitioning to a grad Co-op position.

Leps, Thomas↗

NASA NTRS2017

Land surface Verification Toolkit (LVT)

LVT is a framework developed to provide an automated, consolidated environment for systematic land surface model evaluation Includes support for a range of in-situ, remote-sensing and other model and reanalysis products. Supports the analysis of outputs from various LIS subsystems, including LIS-DA, LIS-OPT, LIS-UE. Note: The Land Information System Verification Toolkit (LVT) is a NASA software tool designed to enable the evaluation, analysis and comparison of outputs generated by the Land Information System (LIS). The LVT software is released under the terms and conditions of the NASA Open Source Agreement (NOSA) Version 1.1 or later. Land Information System Verification Toolkit (LVT) NOSA.

surface model↗

NASA NTRS2018

Lessons Learned in the Flight Qualification of the S-NPP and NOAA-20 Solar Array Mechanisms

Deployable solar arrays are the energy source used on almost all Earth orbiting spacecraft and their release and deployment are mission-critical; fully testing them on the ground is a challenging endeavor. The 8 meter long deployable arrays flown on two sequential NASA weather satellites were each comprised of three rigid panels almost 2 meters wide. These large panels were deployed by hinges comprised of stacked constant force springs, eddy current dampers, and were restrained through launch by a set of four releasable hold-downs using shape memory alloy release devices. The ground qualification testing of such unwieldy deployable solar arrays, whose design was optimized for orbital operations, proved to be quite challenging and provides numerous lessons learned. A paperwork review and follow-up inspection after hardware storage determined that there were negative torque margins and missing lubricant, this paper will explain how these unexpected issues were overcome. The paper will also provide details on how the hinge subassemblies, the fully-assembled array, and mechanical ground support equipment were subsequently improved and qualified for a follow-on flight with considerably less difficulty. The solar arrays built by Ball Aerospace Corp. for the Suomi National Polar Partnership (S-NPP) satellite and the Joint Polar Satellite System (JPSS-1) satellite (now NOAA-20) were both successfully deployed on-obit and are performing well.

Helfrich, Daniel↗

NASA NTRS2018

Lessons Learned in the Flight Qualification of the S-NPP and NOAA-20 Solar Array Mechanisms

Deployable solar arrays are the energy source used on almost all Earth orbiting spacecraft and their release and deployment are mission-critical; fully testing them on the ground is a challenging endeavor. The 8 meter long deployable arrays flown on two sequential NASA weather satellites were each comprised of three rigid panels almost 2 meters wide. These large panels were deployed by hinges comprised of stacked constant force springs, eddy current dampers, and were restrained through launch by a set of four releasable hold-downs using shape memory alloy release devices. The ground qualification testing of such unwieldy deployable solar arrays, whose design was optimized for orbital operations, proved to be quite challenging and provides numerous lessons learned. A paperwork review and follow-up inspection after hardware storage determined that there were negative torque margins and missing lubricant, this paper will explain how these unexpected issues were overcome. The paper will also provide details on how the hinge subassemblies, the fully-assembled array, and mechanical ground support equipment were subsequently improved and qualified for a follow-on flight with considerably less difficulty. The solar arrays built by Ball Aerospace Corp. for the Suomi National Polar Partnership (SNPP) satellite and the Joint Polar Satellite System (JPSS-1) satellite (now NOAA-20) were both successfully deployed on-obit and are performing well.

Sexton, Adam↗

NASA NTRS2018

Understanding Mercury's Exosphere: Models Derived from MESSENGER Observations: Chapter - 15

The observations of Mercury's exosphere described in Chapter 14 have led to many modeling efforts. Early models were based upon a few simple assumptions and primarily explored the dynamics of sodium atoms pushed anti-sunward by radiation pressure [Ip, 1986; Smyth and Marconi, 1995]. More recently, these early models have been superseded by simulations with an increasing number of interdependent source processes [Leblanc and Johnson, 2003; Mura et al., 2009; Leblanc and Johnson, 2010; Burger et al., 2010, 2012, 2014]. We briefly summarize the source and loss processes before describing the published exosphere models, first for the three species observed almost continuously during the MESSENGER mission by the Ultraviolet and Visible Spectrometer (UVVS) channel of the Mercury Atmospheric and Surface Composition2Spectrometer (MASCS), (Na, Mg and Ca), and then more briefly for other species that have been observed or for which new upper limits have been derived.15.1 Overview of Source and Loss Processes15.1.1 Source Processes15.1.1.1 Thermal DesorptionThermal desorption (or thermal evaporation) is the release of adsorbed atoms from a surface via heating. Thermal desorption is related to the binding energy of the atom on the surface and the vibrational frequency of the bound atom, such that the rate of thermal desorption is given by, (15.1)where TD,

Thermal↗

NASA NTRSDate not supplied

HIFiRE Flight 2 Unstart Reliability Analysis

The objective of this work was to assess the unstart reliability of the HIFiRE Flight 2 system. To do this, a quantification of margins and uncertainties framework was used for comparing model predictions of the predicted combustion induced shock location to the predicted last stable shock location within the isolator. Uncertainty sources included parametric uncertainty in the flight conditions, the heat release model, and turbulence modeling, as well as model verification errors. Additionally, an estimate of model-form uncertainty was established by comparing the model to measured ground test data. A computationally efficient non-intrusive polynomial chaos approach was used to propagate parametric uncertainty through the computational flu-ids dynamics models of both the ground test configuration and the flight vehicle. Compared to direct-connect ground test data, computational fluid dynamics predictions yielded about two duct heights of model-form uncertainty. This was applied to a prediction of flight vehicle unstart margin at the Mach 6.5 flight condition. Building up all of the computational model uncertainty, including parametric uncertainty, verification errors, and the determined model-form uncertainty, a 95% probability level based confidence ratio, or a ratio of total uncertainty to a statistical margin measure, was found to be 0.31 for the flight system.

Thomas K West↗

NASA NTRS1992

Dust and gas jets: Evidence for a diffuse source in Halley's coma

The distribution of dust-scattered intensity in Halley's inner coma is measured with the Vega three-channel spectrometer at three selected wavelengths: 377, 482, and 607 nm. The variation along a cometo-centric radius may be described by a p(sup -s) law where p is the distance between nucleus and optical axis and s is an exponent which is equal to 1 except in an intermediate 3000 less than p less than 7000 km region where s = 1.5. The shape of the radial distribution may be explained with a model including solar radiation pressure effect and quantum scattering efficiencies calculated from Mie theory. Monochromatic images inside an angular sector having its apex at the nucleus show evidence of two dust jets which extend to 40,000 Km. The pixel-to-pixel ratio of two images of dust intensity at 377 and 482 nm shows that the scattered intensity presents an excess of blue coloration in a zone located around the jets between 10,000 and 25,000 km. This coloration is interpreted as being due to a population of sub-micronic grains which result of the fragmentation of dust particles transported in the jets. It is suggested that the diffuse source where an additional quantity of CO was detected might be connected with the presence of a dust jet. In the present scheme, grain particles with a size of several micron or 10 micron would be transported inside a dust jet to distances of several 10,000 km where they would suffer fragmentation and produce sub-micronic particles and a release of gas which would be at the origin of the diffuse source.

Clairemidi, Jacques↗

NASA NTRS2017

Effects of Martian Surface Materials on the Thermal Decomposition of Hydrogen Peroxide

While hydrogen peroxide (H2O2) has been detected in the martian atmosphere, it has not been detected in surface materials. Since the Viking lander mission, we have sent instruments to Mars with the capability to detect H2O2. The Sample Analysis at Mars (SAM) instrument onboard the Curiosity Rover and Thermal and Evolved Gas Analyzer (TEGA) instrument on the Phoenix lander both detected water and oxygen releases from analyzed sediments but whether or not peroxide could be the source of these gases has not been investigated. We are investigating the possible presence of H2O2 in martian materials by analyzing Mars-relevant minerals that have been mixed with hydrogen peroxide using lab instruments configured as analogs to Mars mission instruments. The object of this research is to use lab instruments to find the effects of Mars analog minerals on hydrogen peroxide gas release temperatures, specifically gas releases of water and oxygen and also determine the effect of the peroxide on the minerals. Data that we get from the lab can then be compared to the data collected from Mars. The minerals hematite, siderite, San Carlos olivine, magnetite and nontronite were chosen as our Mars analog minerals. ~20 mg of analog Mars minerals with 5μl of 50% H2O2, and were either run immediately or placed in a sealed tube for 2, 4, or 9 days to look for changes over time with two reps being done at each time step to determine repeatability. Each sample was heated from -60 degC to 500 degC at 20 degC/min and the evolved gases were monitored with a mass spectrometer. Each sample was also analyzed with an X-ray diffraction instrument to look for changes in mineralogy. Preliminary results show three potential outcomes: 1) peroxide has no effect on the sample (e.g., hematite), 2) the mineral is unaffected but catalyzes peroxide decomposition (magnetite, siderite), or 3) peroxide alters the mineral (pyrrhotite, San Carlos olivine).

Archer, P. D., Jr.↗

DOE OSTI2021

Site 300 (Facility ID N-472) Toxic Emissions Inventory Plan

The Air Toxics "Hot Spots" Information and Assessment Act (AB 2588 or the “Act”) was enacted in September 1987. Under the Act, stationary sources are required to report the types and quantities of certain toxic substances their facilities routinely release into the air. AB 2588 is designed to provide information to state and local agencies and to the general public on the extent of airborne emissions from stationary sources and the potential public health impacts of those emissions. The San Joaquin Valley Air Pollution Control District (the District) is mandated by the State to implement AB 2588. On March 6, 2015, The State Office of Environmental Health Hazard Assessment (OEHHA) adopted changes to the Air Toxics Hot Spots Program Guidance Manual for the Preparation of Health Risk Assessments. These revisions were designed to incorporate three technical support documents and to provide enhanced protection of children as required under state law (SB 25, Escutia, 1999). Due to these recent changes, and the corresponding potential increases in calculated health risk, the District notified LAWRENCE LIVERMORE NATL SECURITY, LLC that we must be re-evaluated under AB 2588. Pursuant to the Air Toxics "Hot Spots" Information and Assessment Act of 1987, we have prepared a comprehensive, site-specific Toxics Emissions Inventory Plan. The plan specifies in detail how LAWRENCE LIVERMORE NATL SECURITY, LLC will inventory our facility's emissions of all toxic substances on the list of substances subject to the Act. The plan provides a comprehensive and detailed description of the methods that will be used to quantify air releases or potential air releases of listed substances from all points of release. The plan also includes quantification methods which result in accurate and comprehensive characterization of releases and comply with all applicable requirements of the “Hot Spots” regulation.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2022

Lawrence Livermore National Security, LLCSite 300: Toxic Emissions Inventory Plan for ABA 2588 California Air Toxics "Hot Spots" Information and Assessment Act of 1987 (Revision 3.0)

The Air Toxics "Hot Spots" Information and Assessment Act (AB 2588 or the “Act”) was enacted in September 1987. Under the Act, stationary sources are required to report the types and quantities of certain toxic substances their facilities routinely release into the air. AB 2588 is designed to provide information to state and local agencies and to the general public on the extent of airborne emissions from stationary sources and the potential public health impacts of those emissions. The San Joaquin Valley Air Pollution Control District (the District) is mandated by the State to implement AB 2588. On March 6, 2015, The State Office of Environmental Health Hazard Assessment (OEHHA) adopted changes to the Air Toxics Hot Spots Program Guidance Manual for the Preparation of Health Risk Assessments. These revisions were designed to incorporate three technical support documents and to provide enhanced protection of children as required under state law (SB 25, Escutia, 1999). Due to these recent changes, and the corresponding potential increases in calculated health risk, the District notified LAWRENCE LIVERMORE NATIONAL SECURITY, LLC that we must be re-evaluated under AB 2588. Pursuant to the Air Toxics "Hot Spots" Information and Assessment Act of 1987, we have prepared a comprehensive, site-specific Toxics Emissions Inventory Plan. The plan specifies in detail how LAWRENCE LIVERMORE NATIONAL SECURITY, LLC will inventory our facility's emissions of all toxic substances on the list of substances subject to the Act. The plan provides a comprehensive and detailed description of the methods that will be used to quantify air releases or potential air releases of listed substances from all points of release. The plan also includes quantification methods which result in accurate and comprehensive characterization of releases and comply with all applicable requirements of the “Hot Spots” regulation.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2021

Immobilization of Uranium in a Wetland 8-km Downstream from an Industrial Source (Report)

A three-day walk-over survey with portable gamma detecting equipment was conducted over a uranium-contaminated wetland located 8-km downstream from a former fuel fabrication facility. 97,000 spectra were collected, individually processed to extract uranium activity data, and then integrated with topographical information (LIDAR) to create maps. These maps reveal that 50 years after being released into the environment, 11% of the uranium is retained in the 9-ha wetland area. Combined with measurement collected closer to the source, it was determined that 94% of the released uranium is presently being held in downstream wetlands. This demonstrates that wetlands can be very effective at immobilizing contaminants for long durations. The survey also showed that previous flyover maps overestimated the size of the contaminated areas by 140% but had the advantage of being completed in orders-of-magnitude fewer labor hours. Depending on project needs, the walk-over technique may be useful to include in tandem with flyover measurements to acquire maps with greater sensitivity and spatial resolution.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2021

Lawrence Livermore National Security, LLC Site 300 Facility ID N-472 Toxics Emissions Inventory Plan for AB 2588 California Air Toxics "Hot Spots" Information and Assessment Act of 1987

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS2021

Leveraging the ALMA Atacama Compact Array for Cometary Science: An Interferometric Survey of Comet C/2015 ER61 (PanSTARRS) and Evidence for a Distributed Source of Carbon Monosulfide

We report the first survey of molecular emission from cometary volatiles using standalone Atacama Compact Array (ACA) observations from the Atacama Large Millimeter/Submillimeter Array (ALMA) toward comet C/2015 ER61 (PanSTARRS) carried out on UT 2017 April 11 and 15, shortly after its April 4 outburst. These measurements of HCN, CS, CH3OH, H2CO, and HNC (along with continuum emission from dust) probed the inner coma of C/2015 ER61, revealing asymmetric outgassing and discerning parent from daughter/distributed source species. This work presents spectrally integrated flux maps, autocorrelation spectra, production rates, and parent scale lengths for each molecule and a stringent upper limit for CO. HCN is consistent with direct nucleus release in C/2015 ER61, whereas CS, H2CO, HNC, and potentially CH3OH are associated with distributed sources in the coma. Adopt- ing a Haser model, parent scale lengths determined for H2CO (Lp ∼ 2200 km) and HNC (Lp ∼ 3300 km) are consistent with previous work in comets, whereas significant extended source production (Lp ∼ 2000 km) is indicated for CS, suggesting production from an unknown parent in the coma. The con- tinuum presents a point-source distribution with a flux density implying an excessively large nucleus, inconsistent with other estimates of the nucleus size. It is best explained by the thermal emission of slowly moving outburst ejectas, with total mass 5–8 × 1010 kg. These results demonstrate the power of the ACA for revealing the abundances, spatial distributions, and locations of molecular production for volatiles in moderately bright comets such as C/2015 ER61.

Molecular spectroscopy (2095) — High resolution sp↗

NASA NTRS2021

Leveraging the Atacama Compact Array for Cometary Science: An Interferometric Survey of Comet C/2015 ER61 (PanSTARRS) and Evidence for a Distributed Source of Carbon Monosulfide

We report the first survey of molecular emission from cometary volatiles using standalone Atacama Compact Array (ACA) observations from the Atacama Large Millimeter/Submillimeter Array (ALMA) toward comet C/2015 ER61 (PanSTARRS) carried out on UT 2017 April 11 and 15, shortly after its April 4 outburst. These measurements of HCN, CS, CH3OH, H2CO, and HNC (along with continuum emission from dust) probed the inner coma of C/2015 ER61, revealing asymmetric outgassing and discerning parent from daughter/distributed source species. This work presents spectrally integrated flux maps, autocorrelation spectra, production rates, and parent scale lengths for each molecule and a stringent upper limit for CO. HCN is consistent with direct nucleus release in C/2015 ER61, whereas CS, H2CO, HNC, and potentially CH3OH are associated with distributed sources in the coma. Adopt- ing a Haser model, parent scale lengths determined for H2CO (Lp ∼ 2200 km) and HNC (Lp ∼ 3300 km) are consistent with previous work in comets, whereas significant extended source production (Lp ∼ 2000 km) is indicated for CS, suggesting production from an unknown parent in the coma. The continuum presents a point-source distribution with a flux density implying an excessively large nucleus, inconsistent with other estimates of the nucleus size. It is best explained by the thermal emission of slowly moving outburst ejectas, with total mass 5–8 × 1010 kg. These results demonstrate the power of the ACA for revealing the abundances, spatial distributions, and locations of molecular production for volatiles in moderately bright comets such as C/2015 ER61.

Molecular spectroscopy↗

DOE OSTI2022

The population of hot subdwarf stars studied with Gaia: IV. Catalogues of hot subluminous stars based on Gaia EDR3

In light of substantial new discoveries of hot subdwarfs by ongoing spectroscopic surveys and the availability of the Gaia mission Early Data Release 3 (EDR3), we compiled new releases of two catalogues of hot subluminous stars: The data release 3 (DR3) catalogue of the known hot subdwarf stars contains 6616 unique sources and provides multi-band photometry, and astrometry from Gaia EDR3 as well as classifications based on spectroscopy and colours. This is an increase of 742 objects over the DR2 catalogue. This new catalogue provides atmospheric parameters for 3087 stars and radial velocities for 2791 stars from the literature. In addition, we have updated the Gaia Data Release 2 (DR2) catalogue of hot subluminous stars using the improved accuracy of the Gaia EDR3 data set together with updated quality and selection criteria to produce the Gaia EDR3 catalogue of 61 585 hot subluminous stars, representing an increase of 21 785 objects. Furthermore, the improvements in Gaia EDR3 astrometry and photometry compared to Gaia DR2 have enabled us to define more sophisticated selection functions. In particular, we improved hot subluminous star detection in the crowded regions of the Galactic plane as well as in the direction of the Magellanic Clouds by including sources with close apparent neighbours but with flux levels that dominate the neighbourhood.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS2022

Phase II and III Solid Waste Management Unit Assessment and Confirmatory Sampling Report for Per- and Polyfluorinated Alkyl Substances, Potential Release Location 237, Kennedy Space Center, Florida

Per- and polyfluoroalkyl substances (PFAS) Phase II and III Solid Waste Management Unit (SWMU) Assessment (SA) and Confirmatory Sampling (CS) were conducted at the John F. Kennedy Space Center (KSC), Potential Release Location (PRL) 237, located in Merritt Island, Brevard County, Florida for the National Aeronautics and Space Administration (NASA) under Contract 80KSC019D0010/80KSC019F0289. A Phase I SA and CS Report was previously submitted that identified 33 locations of concern (LOCs) at KSC associated with the storage, use, or release of materials containing PFAS. The objectives of the Phase II and III SA and CS were to: - Complete site and source characterization of identified LOCs; - Identify areas of potential concern (AOPCs) where past or present activities may have resulted in a release of PFAS to the environment; - Qualitatively characterize migration potential of released PFAS to environmental media (primarily soil, groundwater, surface water, and sediment); and - Identify potential receptors for exposure to PFAS-impacted environmental media. Surface water samples were collected from LOCs/AOPCs and locations on the KSC periphery during PFAS CS Phases I, II and III. Including duplicate samples, 143 environmental samples were analyzed for 14 PFAS compounds and 104 environmental samples were analyzed for 18 PFAS compounds. Ten of the analytes on the 14 compound list were detected at least once in surface water at KSC, with a wide range in magnitude of detections. The State of Florida has surface water screening levels (SWSLs) for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in surface water, both for human and ecological receptors. The human health screening levels are lower than the ecological ones and are used in this report. PFOA was not detected in surface water at concentrations exceeding the SWSL at any LOC or Area of Potential Concern (AOPC). PFOS was detected in surface water at concentrations exceeding the SWSL at 28 LOCs/AOPCs, plus 42 locations on the KSC periphery. The data suggest a wide distribution of PFAS, particularly PFOS, in surface water but the sources of surface water contamination are not yet adequately understood. Sediment samples were collected during Phases II and III but not Phase I. Including duplicate samples, 104 environmental samples were analyzed for 14 PFAS compounds and 10 environmental samples were analyzed for 18 PFAS compounds. Twelve compounds were detected in sediment at KSC, with a wide range in magnitude of detections. There are currently no screening levels or cleanup target levels (CTLs) for sediment. The need to delineate and further characterize PFAS in sediment will be evaluated for those sites that move forward into Site Assessment. Groundwater samples were collected via DPT from LOCs/AOPCs and locations on the KSC periphery during PFAS CS Phases I, II and III. Including duplicate samples, 812 environmental DPT groundwater samples were analyzed for 14 PFAS compounds and 247 environmental samples were analyzed for 18 PFAS compounds. Twelve of the 14 compounds were detected in groundwater at KSC, with a wide range in magnitude of detections. The State of Florida has provisional groundwater cleanup target levels (GCTLs) for PFOA, PFOS and the additive concentration of PFOA+PFOS. PFOA was detected in groundwater at concentrations exceeding its provisional GCTL at 16 LOCs/AOPCs, with no exceedances on the KSC periphery. PFOS was detected in groundwater at concentrations exceeding its provisional GCTL at 30 LOCs/AOPCs, plus two locations on the KSC periphery. PFOA+PFOS was detected in groundwater at concentrations exceeding the provisional GCTL at 31 LOCs/AOPCs, plus two locations on the KSC periphery. Soil samples were collected during Phases II and III but not Phase I. Including duplicate samples, 292 environmental samples were analyzed for 14 PFAS compounds and 80 environmental samples were analyzed for 18 PFAS compounds. Fourteen compounds were detected in soil at KSC, with a wide range in magnitude of detections. The State of Florida has provisional soil cleanup target levels (SCTLs) for PFOA and PFOS. There were no PFOA results above its provisional SCTL. There was one LOC with a result above the provisional SCTL for residential settings. Recommendations are presented for each LOC and AOPC.

PFAS↗

NASA NTRS1992

Control of on-orbit contamination for the Argos (P91-1) satellite

The ARGOS (P91-1) satellite presents a challenging combination of on-orbit contamination concerns while mandating a low-cost approach. Several experiment payloads contain contamination sensitive optics, another contains large quantities of CO2 and Xe for release in orbit, and one contains an NH3 fueled arc jet thruster. The latter includes a suite of sensors to measure contamination; so prelaunch calculations will be tested. Planned contamination control techniques include: physical separation of sensitive surfaces from contamination sources; flight covers to protect sensitive surfaces during early outgassing on-orbit; gas release and thruster operation early in the flight, before flight covers are opened; and careful control of plumes and venting through a detailed analysis of each.

Kelley, Joseph G.↗

DOE OSTI2020

An Improved Energy Deposition Model in MPACT and Explicit Heat Generation Coupling with CTF

The default energy deposition model in the CASL neutronics code MPACT assumes all fission energy is deposited locally in fuel rods. Furthermore, equilibrium delayed energy release is assumed for both steady-state and transient calculations. These approximations limit the accurate representation of the heat generation distribution in space and its variations over time, which are essential for power distribution and thermal-hydraulic coupling calculations. In this paper, an improved energy deposition model is presented in both the spatial and time domains. Spatially, the energy deposition through fission, neutron capture, and slowing-down reactions are explicitly modeled to account for the heat generation from all regions of a reactor core, and a gamma smearing scheme is developed that utilizes the gamma sources from neutron fission and capture. In the time domain, the delayed energy release is modeled by solving an additional equation of delayed heat emitters, similar to the equation of delayed neutron precursors.To allow the explicit heat generation coupling, the interfaces between MPACT and CTF were updated to transfer separate heat sources for different material regions (fuel, clad, moderator and guide tube). The results show that the distributions of the energy deposition between MPACT and MCNP agree very well for various 2-D assembly and quarter-core problems without TH feedback. The MPACT/CTF coupled calculation for the hot full power quarter-core case exhibited a reduced peak pin power by 2.3% and a reduced peak fuel centerline temperature by 17 K when using the explicit energy deposition and heat transfer. The new model also shows a maximum 100 pcm keff effect on assembly depletion problems and an increased overall energy release by 7% in a PWR reactivity-initiated accident (RIA) problem.

Liu, Yuxuan↗