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At least 253 records · Page 14

An Experimental Investigation of Silicone-to-Metal Bond Strength in Composite Space Docking System Seals

The National Aeronautics and Space Administration (NASA) is currently developing a new universal docking mechanism for future space exploration missions called the Low Impact Docking System (LIDS). A candidate LIDS main interface seal design is a composite assembly of silicone elastomer seals vacuum molded into grooves in an electroless nickel plated aluminum retainer. The strength of the silicone-tometal bond is a critical consideration for the new system, especially due to the presence of small areas of disbond created during the molding process. In the work presented herein, seal-to-retainer bonds of subscale seal specimens with different sizes of intentional disbond were destructively tensile tested. Nominal specimens without intentional disbonds were also tested. Tension was applied either uniformly on the entire seal circumference or locally in one short circumferential length. Bond failure due to uniform tension produced a wide scatter of observable failure modes and measured load-displacement behaviors. Although the preferable failure mode for the seal-to-retainer bond is cohesive failure of the elastomer material, the dominant observed failure mode under the uniform loading condition was found to be the less desirable adhesive failure of the bond in question. The uniform tension case results did not show a correlation between disbond size and bond strength. Localized tension was found to produce failure either as immediate tearing of the elastomer material outside the bond region or as complete peel-out of the seal in one piece. The obtained results represent a valuable benchmark for comparison in the future between adhesion loads under various separation conditions and composite seal bond strength.

Gaier, James R.↗

Temperature and Atomic Oxygen Effects on Helium Leak Rates of a Candidate Main Interface Seal

Helium leak tests were completed to characterize the leak rate of a 54 in. diameter composite space docking seal design in support of the National Aeronautics and Space Administration s (NASA's) Low Impact Docking System (LIDS). The evaluated seal design was a candidate for the main interface seal on the LIDS, which would be compressed between two vehicles, while docked, to prevent the escape of breathable air from the vehicles and into the vacuum of space. Leak tests completed at nominal temperatures of -30, 20, and 50 C on untreated and atomic oxygen (AO) exposed test samples were examined to determine the influence of both test temperature and AO exposure on the performance of the composite seal assembly. Results obtained for untreated seal samples showed leak rates which increased with increased test temperature. This general trend was not observed in tests of the AO exposed specimens. Initial examination of collected test data suggested that AO exposure resulted in higher helium leak rates, however, further analysis showed that the differences observed in the 20 and 50 C tests between the untreated and AO exposed samples were within the experimental error of the test method. Lack of discernable trends in the test data prevented concrete conclusions about the effects of test temperature and AO exposure on helium leak rates of the candidate seal design from being drawn. To facilitate a comparison of the current test data with results from previous leak tests using air as the test fluid, helium leak rates were converted to air leak rates using standard conversion factors for viscous and molecular flow. Flow rates calculated using the viscous flow conversion factor were significantly higher than the experimental air leakage values, whereas values calculated using the molecular flow conversion factor were significantly lower than the experimentally obtained air leak rates. The difference in these sets of converted flow rates and their deviation from the experimentally obtained air leak rate data suggest that neither conversion factor can be used alone to accurately convert helium leak rates to equivalent air leak rates for the test seals evaluated in this study; other leak phenomena, including permeation, must also be considered.

Penney, Nicholas↗

NASA Docking System (NDS) Interface Definitions Document (IDD)

The NASA Docking System (NDS) mating system supports low approach velocity docking and provides a modular and reconfigurable standard interface, supporting crewed and autonomous vehicles during mating and assembly operations. The NDS is NASA's implementation for the emerging International Docking System Standard (IDSS) using low impact docking technology. All NDS configurations can mate with the configuration specified in the IDSS Interface Definition Document (IDD) released September 21, 2010. The NDS evolved from the Low Impact Docking System (LIDS). The acronym international Low Impact Docking System (iLIDS) is also used to describe this system. NDS and iLIDS may be used interchangeability. Some of the heritage documentation and implementations (e.g., software command names) used on NDS will continue to use the LIDS acronym. The NDS IDD defines the interface characteristics and performance capability of the NDS, including uses ranging from crewed to autonomous space vehicles and from low earth orbit to deep space exploration. The responsibility for developing space vehicles and for making them technically and operationally compatible with the NDS rests with the vehicle providers. Host vehicle examples include crewed/uncrewed spacecraft, space station modules, elements, etc. Within this document, any docking space vehicle will be referred to as the host vehicle. This document defines the NDS-to-NDS interfaces, as well as the NDS-to-host vehicle interfaces and performance capability.

Source record↗

International Low Impact Docking System (iLIDS) Project Technical Requirements Specification, Revision F

The NASA Docking System (NDS) is NASA's implementation for the emerging International Docking System Standard (IDSS) using low impact docking technology. The NASA Docking System Project (NDSP) is the International Space Station (ISS) Program's project to produce the NDS, Common Docking Adapter (CDA) and Docking Hub. The NDS design evolved from the Low Impact Docking System (LIDS). The acronym international Low Impact Docking System (iLIDS) is also used to describe this system as well as the Government Furnished Equipment (GFE) project designing the NDS for the NDSP. NDS and iLIDS may be used interchangeability. This document will use the acronym iLIDS. Some of the heritage documentation and implementations (e.g., software command names, requirement identification (ID), figures, etc.) used on NDS will continue to use the LIDS acronym. This specification defines the technical requirements for the iLIDS GFE delivered to the NDSP by the iLIDS project. This document contains requirements for two iLIDS configurations, SEZ29101800-301 and SEZ29101800-302. Requirements with the statement, iLIDS shall, are for all configurations. Examples of requirements that are unique to a single configuration may be identified as iLIDS (-301) shall or iLIDS (-302) shall. Furthermore, to allow a requirement to encompass all configurations with an exception, the requirement may be designated as iLIDS (excluding -302) shall. Verification requirements for the iLIDS project are identified in the Verification Matrix (VM) provided in the iLIDS Verification and Validation Document, JSC-63966. The following definitions differentiate between requirements and other statements: Shall: This is the only verb used for the binding requirements. Should/May: These verbs are used for stating non-mandatory goals. Will: This verb is used for stating facts or declaration of purpose. A Definition of Terms table is provided in Appendix B to define those terms with specific tailored uses in this document.

Lewis, James L.↗

NASA Docking System (NDS) Interface Definitions Document (IDD)

The NASA Docking System (NDS) mating system supports low approach velocity docking and provides a modular and reconfigurable standard interface, supporting crewed and autonomous vehicles during mating and assembly operations. The NDS is NASA s implementation for the International Docking System Standard (IDSS) using low impact docking technology. All NDS configurations can mate with the configuration specified in the IDSS Interface Definition Document (IDD), Revision A, released May 13, 2011. The NDS evolved from the Low Impact Docking System (LIDS). The term (and its associated acronym), international Low Impact Docking System (iLIDS) is also used to describe this system. NDS and iLIDS may be used interchangeability. Some of the heritage documentation and implementations (e.g., software command names) used on the NDS will continue to use the LIDS acronym.

Lewis, James↗

Ozone Profiles in the Baltimore-Washington Region (2006-2011): Satellite Comparisons and DISCOVER-AQ Observations

Much progress has been made in creating satellite products for tracking the pollutants ozone and NO2 in the troposphere. Yet, in mid-latitude regions where meteorological interactions with pollutants are complex, accuracy can be difficult to achieve, largely due to persistent layering of some constituents. We characterize the layering of ozone soundings and related species measured from aircraft over two ground sites in suburban Washington, DC (Beltsville, MD, 39.05N; 76.9W) and Baltimore (Edgewood, MD, 39.4N; 76.3W) during the July 2011 DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) experiment. First, we compare column-ozone amounts from the Beltsville and Edgewood sondes with data from overpassing satellites. Second, processes influencing ozone profile structure are analyzed using Laminar Identification and tracers: sonde water vapor, aircraft CO and NOy. Third, Beltsville ozone profiles and meteorological influences in July 2011 are compared to those from the summers of 2006-2010. Sonde-satellite offsets in total ozone during July 2011 at Edgewood and Beltsville, compared to the Ozone Monitoring Instrument (OMI), were 3 percent mean absolute error, not statistically significant. The disagreement between an OMIMicrowave Limb Sounder-based tropospheric ozone column and the sonde averaged 10 percent at both sites, with the sonde usually greater than the satellite. Laminar Identification (LID), that distinguishes ozone segments influenced by convective and advective transport, reveals that on days when both stations launched ozonesondes, vertical mixing was stronger at Edgewood. Approximately half the lower free troposphere sonde profiles have very dry laminae, with coincident aircraft spirals displaying low CO (80-110 ppbv), suggesting stratospheric influence. Ozone budgets at Beltsville in July 2011, determined with LID, as well as standard meteorological indicators, resemble those of 4 of the previous 5 summers. The penetration of stratospheric air throughout the troposphere appears to be typical for summer conditions in the Baltimore-Washington region.

satellite validation↗

Variable Depth Bragg Peak Method for Single Event Effects Testing

Traditionally, accelerator SEE testing is accomplished by removing the tops of packages so that the IC chips are accessible to heavy ions. However, ICs in some advanced packages cannot be de-lidded so a different approach is used that involves grinding and/or chemically etching away part of the package and the chip from the back side. The parts are then tested from the back side with ions having sufficient range to reach the sensitive volume. More recently, the entire silicon substrate in an SOI/SRAM was removed, making it possible to use low-energy ions with shorter ranges. Where removal of part of the package is not possible, facilities at Michigan State, NASA Space Radiation Laboratory, GANIL (France) and GSI (Germany) offer high-energy heavy ions with long ranges so that the ions can reach the devices' sensitive volumes without much change in the LET. Unfortunately, a run will typically involve only one ion species having a single energy and LET due to the long time it takes to tune a new energy. The Variable Depth Bragg Peak (VDBP) method is similar to the above method in that it involves the use of high-energy heavy ions that are able to pass through the packaging material and reach the device, obviating the need to remove the package. However, the method provides a broad range of LETs from a single ion by inserting degraders in the beam that modify the ion energy and, therefore, the LET. The crux of the method involves establishing a fiduciary point for degrader thickness, i.e., where the Bragg peak is located precisely at the sensitive volume in the device, for which the measured SEU cross-section and the ion LET are both also maxima and can be calculated using a Monte-Carlo program, TRIM. Once the fiduciary point has been established, calibrated high density polyethylene (HDPE) degraders are inserted into or removed from the beam to vary the ion LET at the device in a known manner. After each change of degrader thickness, the SEU cross-section is measured and the corresponding LET calculated from the change in degrader thickness. That information is used to generate a plot of cross-section as a function of ion LET. The advantages of this approach are that the part does not have to be de-lidded and a broad range of LETs is available from a single heavy ion without having to go to non-normal angles of incidence to change the "effective" LET. As we will show, it is possible to obtain an entire curve of cross-section versus LET using just two or three ions. Fig. 1 shows curves of cross-section vs LET for a Freescale 4 Mbit SOI/SRAM measured at the 88" Cyclotron at Berkeley and at NSRL. The open symbols are the data obtained from Berkeley for top-side and back-side irradiation. The solid data points are for the data obtained at NSRL using a device for which the package was intact. The data are for Iron and Gold and cover a range of LETs from 4 MeV.cm2/mg to 84 MeV.cm2/mg. The agreement between the data obtained from Berkeley and from NSRL is excellent, demonstrating that the VDBP method is capable of providing accurate values of cross-section versus LET, at least for the 4 Mbit SRAM. Details of the technique will be included in the final presentation.

Buchner, S.↗

Insulation Test Cryostat with Lift Mechanism

A multi-purpose, cylindrical thermal insulation test apparatus is used for testing insulation materials and systems of materials using a liquid boil-off calorimeter system for absolute measurement of the effective thermal conductivity (k-value) and heat flux of a specimen material at a fixed environmental condition (cold-side temperature, warm-side temperature, vacuum pressure level, and residual gas composition). The apparatus includes an inner vessel for receiving a liquid with a normal boiling point below ambient temperature, such as liquid nitrogen, enclosed within a vacuum chamber. A cold mass assembly, including the upper and lower guard chambers and a middle test vessel, is suspended from a lid of the vacuum canister. Each of the three chambers is filled and vented through a single feedthrough. All fluid and instrumentation feedthroughs are mounted and suspended from a top domed lid to allow easy removal of the cold mass. A lift mechanism allows manipulation of the cold mass assembly and insulation test article.

Fesmire, James E.↗

Insulation Test Cryostat with Lift Mechanism

A multi-purpose, cylindrical thermal insulation test apparatus is used for testing insulation materials and systems of materials using a liquid boil-off calorimeter system for absolute measurement of the effective thermal conductivity (k-value) and heat flux of a specimen material at a fixed environmental condition (cold-side temperature, warm-side temperature, vacuum pressure level, and residual gas composition). An inner vessel receives liquid with a normal boiling point below ambient temperature, such as liquid nitrogen, enclosed within a vacuum chamber. A cold mass assembly, including upper and lower guard chambers and middle test vessel, is suspended from a lid of the vacuum canister. Each of the three chambers is filled and vented through a single feedthrough. All fluid and instrumentation feedthroughs are mounted and suspended from a top domed lid allowing easy removal of the cold mass. A lift mechanism allows manipulation of the cold mass assembly and insulation test article.

Fesmire, James E.↗

OSIRIS-REx Curation: The First Year with Bennu Samples on Earth

The OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer) sample return capsule landed on the Utah Test and Training Range (UTTR) on September 24, 2023. Preparations for the curation of the sample from asteroid Bennu inside of this capsule spanned more than a decade. On the morning of landing, the sample return capsule was brought to a temporary cleanroom at UTTR for initial de-integration and connection of the sample canister to a nitrogen gas purge to protect the sample from modification by the terrestrial atmosphere. In the week following landing, the sample canister was flown to Houston while on nitrogen purge, transferred to a nitrogen atmosphere glovebox at NASA Johnson Space Center in which the canister lid was removed revealing small amounts of sample on the inside of the canister lid and avionics deck, some of this sample was allocated rapidly to the mission sample analysis team as “quick look” samples. Next, the Touch-and-Go sample acquisition mechanism (TAGSAM) head was disassembled inside of a specially designed glovebox. A challenge arose during one of the last stages of disassembly when two fasteners resisted being loosened. The curation team was able to remove 70.3 grams of asteroid sample from the TAGSAM head with those fasteners in-place and began initial sample processing which supported long-term curation of hermetically sealed and frozen samples, transfer of some samples to remote storage, and allocation of aggregate samples to the mission sample analysis team. Meanwhile, curation engineers developed a tool to remove the stubborn fasteners without contaminating the remaining sample, enabling the remaining bulk sample to be transferred to long-term storage trays in January 2024. With this second part of the bulk sample, the returned bulk asteroid sample reached 121.6 grams. During disassembly and prior to sealing the bulk sample trays into long-term storage containers, archival photographs were collected. Select particles are gradually being XCT scanned while inside of containers that hold a nitrogen atmosphere. The initial OSIRIS-REx sample catalog was released in spring 2024 with an update in fall 2024. The curation team will be busy working to allocate samples to scientists around the world for the foreseeable future.

Curation↗

Electrode array for neural stimulation

An electrode array for neural stimulation is disclosed which has particular applications for use in a retinal prosthesis. The electrode array can be formed as a hermetically-sealed two-part ceramic package which includes an electronic circuit such as a demultiplexer circuit encapsulated therein. A relatively large number (up to 1000 or more) of individually-addressable electrodes are provided on a curved surface of a ceramic base portion the electrode array, while a much smaller number of electrical connections are provided on a ceramic lid of the electrode array. The base and lid can be attached using a metal-to-metal seal formed by laser brazing. Electrical connections to the electrode array can be provided by a flexible ribbon cable which can also be used to secure the electrode array in place.

47 OTHER INSTRUMENTATION↗

Benchmark Evaluation of Fuel Effect and Material Worth Measurements for a Beryllium-Reflected Space Reactor Mockup

The critical configuration of the small, compact critical assembly (SCCA) experiments performed at the Oak Ridge Critical Experiments Facility (ORCEF) in 1962-1965 have been evaluated as acceptable benchmark experiments for inclusion in the International Handbook of Evaluated Criticality Safety Benchmark Experiments. The initial intent of these experiments was to support the design of the Medium Power Reactor Experiment (MPRE) program, whose purpose was to study "power plants for the production of electrical power in space vehicles." The third configuration in this series of experiments was a beryllium-reflected assembly of stainless-steel-clad, highly enriched uranium (HEU)-O 2 fuel mockup of a potassium-cooled space power reactor. Reactivity measurements cadmium ratio spectral measurements and fission rate measurements were measured through the core and top reflector. Fuel effect worth measurements and neutron moderating and absorbing material worths were also measured in the assembly fuel region. The cadmium ratios, fission rate, and worth measurements were evaluated for inclusion in the International Handbook of Evaluated Criticality Safety Benchmark Experiments. The fuel tube effect and neutron moderating and absorbing material worth measurements are the focus of this paper. Additionally, a measurement of the worth of potassium filling the core region was performed but has not yet been evaluated Pellets of 93.15 wt.% enriched uranium dioxide (UO 2 ) were stacked in 30.48 cm tall stainless steel fuel tubes (0.3 cm tall end caps). Each fuel tube had 26 pellets with a total mass of 295.8 g UO 2 per tube. 253 tubes were arranged in 1.506-cm triangular lattice. An additional 7-tube cluster critical configuration was also measured but not used for any physics measurements. The core was surrounded on all side by a beryllium reflector. The fuel effect worths were measured by removing fuel tubes at various radius. An accident scenario was also simulated by moving outward twenty fuel rods from the periphery of the core so they were touching the core tank. The change in the system reactivity when the fuel tube(s) were removed/moved compared with the base configuration was the worth of the fuel tubes or accident scenario. The worth of neutron absorbing and moderating materials was measured by inserting material rods into the core at regular intervals or placing lids at the top of the core tank. Stainless steel 347, tungsten, niobium, polyethylene, graphite, boron carbide, aluminum and cadmium rods and/or lid worths were all measured. The change in the system reactivity when a material was inserted into the core is the worth of the material.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Device-packaging method and apparatus for optoelectronic circuits

An optoelectronic device package and a method for its fabrication are provided. The device package includes a lid die and an active die that is sealed or sealable to the lid die and in which one or more optical waveguides are integrally defined. The active die includes one or more active device regions, i.e. integral optoelectronic devices or etched cavities for placement of discrete optoelectronic devices. Optical waveguides terminate at active device regions so that they can be coupled to them. Slots are defined in peripheral parts of the active dies. At least some of the slots are aligned with the ends of integral optical waveguides so that optical fibers or optoelectronic devices inserted in the slots can optically couple to the waveguides.

36 MATERIALS SCIENCE↗

High voltage power chip module

A power die module using a compression connection to a power die in a small package with corona extenders positioned around short efficient path exterior electrical connections. The module is built from a baseplate with connected sidewalls forming an interior compartment holding a power substrate with attached threaded inserts. A printed circuit board bolted to the power substrate with high voltage power die compressively held between the board and the substrate. The compressive hold enhances the electrical connections between the contacts on the top and bottom of the power die and either the power substrate or the printed circuit board. Exterior blade connectors extend upward from the printed circuit board through blade apertures in a lid that covers the interior compartment. The lid includes corona extenders positioned around the blade apertures to allow for high voltage applications while maintaining a small size lightweight package. The sidewall has a perimeter that also includes one or more corona extenders.

42 ENGINEERING↗

Secondary fusion coupled deuteron/triton transport simulation and thermal-to-fusion neutron convertor measurement

A Monte Carlo tool RSMC (Reaction Sequence Monte Carlo) was developed to simulate deuteron/triton transportation and reaction coupled problem. The 'Forced particle production' variance reduction technique was used to improve the simulation speed, which made the secondary product play a major role. The mono-energy 14 MeV fusion neutron source was employed as a validation. Then the thermal-to-fusion neutron convertor was studied with our tool. Moreover, an in-core conversion efficiency measurement experiment was performed with {sup 6}LiD and {sup 6}LiH converters. Threshold activation foils was used to indicate the fast and fusion neutron flux. Besides, two other pivotal parameters were calculated theoretically. Finally, the conversion efficiency of {sup 6}LiD is obtained as 1.97x10{sup -4}, which matches well with the theoretical result. (authors)

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

A Cask Processing Enclosure for the TRU Waste Processing Center - 13408

This paper will discuss the key elements considered in the design, construction, and use of an enclosure system built for the TRU Waste Processing Center (TWPC). The TWPC system is used for the repackaging and volume reduction of items contaminated with radioactive material, hazardous waste and mixed waste. The modular structural steel frame and stainless steel skin was designed for rapid field erection by the use of interchangeable self-framing panel sections to allow assembly of a sectioned containment building and for ease of field mobility. The structure was installed on a concrete floor inside of an outer containment building. The major sections included an Outer Cask Airlock, Inner Cask Airlock, Cask Process Area, and Personnel Airlocks. Casks in overpacks containing transuranic waste are brought in via an inter-site transporter. The overpack lid is removed and the cask/overpack is transferred into the Outer Cask Airlock. A contamination cover is installed on the overpack body and the Outer Cask Airlock is closed. The cask/overpack is transferred into the Inner Cask Airlock on a cask bogie and the Inner Cask Airlock is closed. The cask lid is removed and the cask is transferred into the Cask Process Area where it is placed on a cask tilting station. Once the Cask Processing Area is closed, the cask tilt station is activated and wastes are removed, size reduced, then sorted and re-packaged into drums and standard waste boxes through bag ports. The modular system was designed and built as a 'Fast Track' project at IP Systems in Broomfield Colorado and then installed and is currently in use at the DOE TWPC located near Oak Ridge, Tennessee. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Pressure Build-Up During the Fire Test in Type B(U) Packages Containing Water - 13280

The safety assessment of packages for the transport of radioactive materials with content containing liquids requires special consideration. The main focus is on water as supplementary liquid content in Type B(U) packages. A typical content of a Type B(U) package is ion exchange resin, waste of a nuclear power plant, which is not dried, normally only drained. Besides the saturated ion exchange resin, a small amount of free water can be included in these contents. Compared to the safety assessment of packages with dry content, attention must be paid to some more specific issues. An overview of these issues is provided. The physical and chemical compatibility of the content itself and the content compatibility with the packages materials must be demonstrated for the assessment. Regarding the mechanical resistance the package has to withstand the forces resulting from the freezing liquid. The most interesting point, however, is the pressure build-up inside the package due to vaporization. This could for example be caused by radiolysis of the liquid and must be taken into account for the storage period. If the package is stressed by the total inner pressure, this pressure leads to mechanical loads to the package body, the lid and the lid bolts. Thus, the pressure is the driving force on the gasket system regarding the activity release and a possible loss of tightness. The total pressure in any calculation is the sum of partial pressures of different gases which can be caused by different effects. The pressure build-up inside the package caused by the regulatory thermal test (30 min at 800 deg. C), as part of the cumulative test scenario under accident conditions of transport is discussed primarily. To determine the pressure, the temperature distribution in the content must be calculated for the whole period from beginning of the thermal test until cooling-down. In this case, while calculating the temperature distribution, conduction and radiation as well as evaporation and condensation during the associated process of transport have to be considered. This paper discusses limiting amounts of water inside the cask which could lead to unacceptable pressure and takes into account saturated steam as well as overheated steam. However, the difficulties of assessing casks containing wet content will be discussed. From the authority assessment point of view, drying of the content could be an effective way to avoid the above described pressure build-up and the associated difficulties for the safety assessment. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗