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

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Ablative heat shield design for space shuttle

Ablator heat shield configuration optimization studies were conducted for the orbiter. Ablator and reusable surface insulation (RSI) trajectories for design studies were shaped to take advantage of the low conductance of ceramic RSI and high temperature capability of ablators. Comparative weights were established for the RSI system and for direct bond and mechanically attached ablator systems. Ablator system costs were determined for fabrication, installation and refurbishment. Cost penalties were assigned for payload weight penalties, if any. The direct bond ablator is lowest in weight and cost. A mechanically attached ablator using a magnesium subpanel is highly competitive for both weight and cost.

Seiferth, R. W.↗
DOE OSTI2012

Guidelines for beamline and front-end radiation shielding design at the Advanced Photon Source

Shielding for the APS will be such that the individual radiation worker dose will be as low as reasonably achievable (ALARA). The ALARA goals for the APS are to keep the total of the work-related radiation exposure (exposure coming from other than natural or medical sources) as far below 500 person-mrem per year, collective total effective dose equivalent, as reasonably achievable.

Fernandez, P.↗
DOE OSTI2017

Initial experimental demonstration of the principles of a xenon gas shield designed to protect optical components from soft x-ray induced opacity (blanking) in high energy density experiments

The design principles of a xenon gas shield device that is intended to protect optical components from x-ray induced opacity (“x-ray blanking”) have been experimentally demonstrated at the OMEGA-60 Laser Facility at the Laboratory for Laser Energetics, University of Rochester. A volume of xenon gas placed in front of an optical component absorbs the incoming soft x-ray radiation but transmits optical and ultra-violet radiation. The time-resolved optical (532 nm) transmission of samples was recorded as they were exposed to soft x-rays produced by a gold sphere source (1.5 kJ sr $-$1 , 250–300 eV). Blanking of fused silica (SiO 2 ) was measured to occur over a range of time-integrated soft x-ray (<3 keV) fluence from ~0.2–2.5 J cm $-$2 . A shield test device consisting of a 30 nm silicon nitride (Si 3 N 4 ) and a 10 cm long volume of 0.04 bar xenon gas succeeded in delaying loss of transmission through a magnesium fluoride sample; optical transmission was observed over a longer period than for the unprotected sample. It is hoped that the design of this x-ray shield can be scaled in order to produce a shield device for the National Ignition Facility optical Thomson scattering collection telescope, in order to allow measurements of hohlraum plasma conditions produced in inertial confinement fusion experiments. Finally, if successful, it will also have applications in many other high energy density experiments where optical and ultra-violet measurements are desirable.

42 ENGINEERING↗
DOE OSTI2018

Shielding design for the LANSCE/WNR neutron flight paths - 25334

The shielding surrounding the spallation target and the neutron flight paths at the Los Alamos Neutron Science Center Weapons Neutron Research facility is simulated using a detailed MCNPX Monte Carlo model to determine neutron and γ-ray backgrounds in the experimental areas. In some cases the shielding needs to be modified depending on the requirements of planned experiments. (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2014

Guidelines for Beamline and Front-End Radiation Shielding Design at the Advanced Photon Source (Rev. 5)

Shielding for the APS will be such that the individual radiation worker dose will be as low as reasonably achievable (ALARA). The ALARA goals for the APS are to keep the total of the work-related radiation exposure (exposure coming from other than natural or medical sources) as far below 5 person mSv/yr (500 person-mrem/yr), collective total effective dose equivalent, as reasonably achievable. For an individual APS radiation worker, the goal is to keep the maximum occupational total effective dose equivalent of any one employee as far below 2 mSv/yr as reasonably achievable. The ALARA goal for APS beamline scientists is to keep the total of the work-related radiation exposure (exposure coming from other than natural or medical sources) as far below 1 person mSv/yr (100 person-mrem/yr), collective total effective dose equivalent, as reasonably achievable. For an individual APS beamline scientist, the goal is to keep the maximum occupational total effective dose equivalent of any one scientist as far below 0.5 mSv/yr (50 mrem/yr) as reasonably achievable. The dose is actively monitored by the radiation monitors on the storage ring wall in each sector and by the frequent area surveys performed by the health physics personnel. For cases in which surveys indicate elevated hourly dose rates that may impact worker exposure, additional local shielding is provided to reduce the radiation field to an acceptable level. Passive area monitors are used throughout the facility to integrate doses in various areas. The results are analyzed for trends of increased doses, and shielding in these areas is evaluated and improved, as appropriate. The APS policy for on-site nonradiation workers in the vicinity of the APS facilities requires that the average nonradiation worker dose be below 0.2 mSv/yr (20 mrem/yr). In addition, the dose at the site boundary from all pathways is required to be below 0.1 mSv/yr (10 mrem/yr). For future modifications of the facility, the doses shall be evaluated and additional shielding provided to meet the policy requirements.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2016

Layered shielding design for an active neutron interrogation system

The use of source and detector shields in active neutron interrogation can improve detector signal. In simulations, a shielded detector with a source rotated π/3 rad relative to the opening decreased neutron flux roughly three orders of magnitude. Several realistic source and detector shield configurations were simulated. A layered design reduced neutron and secondary photon flux in the detector by approximately one order of magnitude for a deuterium–tritium source. The shield arrangement can be adapted for a portable, modular design.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Rachet Door Shielding Design Calculations

The ratchet wall at the experimental floor side will have sliding doors to provide access to beamline front ends during installation and maintenance. The thickness and design of these sliding doors should provide shielding equivalence of the concrete thickness of the ratchet wall. Each of the sliding doors will be a composite to provide effective shielding from neutron and gamma radiation, emanating from beam losses inside the storage ring.

36 MATERIALS SCIENCE↗
NASA NTRS1974

Major uncertainties influencing entry probe heat shield design

Factors influencing the design of an outer planet probe heat shield are discussed. Major factors included are: uncertainties in composition and scale height of the planet atmospheres; the augmentation/attenuation of entry heating by ablation products requires more computer study and testing; carbon heat shields, especially carbon phenolic, possessing improved resistance to spallation need developing; and white silica reflecting heat shields with improved resistance to bulk vitrification need further developing.

Congdon, W.↗
DOE OSTI2016

Verification of the Prompt Radiation Shielding Design of the ESS Accelerator

Fermilab will perform prompt radiation and shielding verification studies for the European Spallation Source ERIC (ESS) accelerator tunnel and existing penetration layouts using the latest information on the beam line and existing models of magnets and cryomodules. The input information about the assumptions, geometry layout, etc. will be provided by the Safety Group (accelerator division, ESS). The MEDT department of the Accelerator Division, Fermilab will provide the results of the studies. MARS15, a Fermilab a multi-purpose Monte-Carlo code developed since 1974, is at the heart of this effort. MARS15 is used for detailed simulation of hadronic and electromagnetic cascades in an arbitrary 3-D geometry of shielding, accelerator, detector and spacecraft components with energy ranging from a fraction of an electronvolt to 100 TeV. This work will provide additional validation of recent additions to the physical models in the code, including the code capabilities to simulate cascades and generate a variety of results in complex media.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

ALARA Review of NSLS-II Shielding Design

Radiation exposure to staff and users as the result of National Synchrotron Light Source II (NSLS-II) operations must comply with Brookhaven National Laboratory (BNL) and Department of Energy (DOE) radiation requirements and must be maintained as low as reasonably achievable (ALARA). The purpose of this document is to review the basis for the design choices used to limit radiation exposure at NSLS-II and demonstrate that the shielding and other radiological design features have been effectively and optimally integrated into the design of NSLS-II facilities.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Revised Guidelines for the NSLS-II Beamline Shielding Design

The annual dose to NSLS-II1 beamline scientists will be kept well below federal limits and within BNL administrative levels through shielding, operational procedures, and administrative controls. Shielding guidelines to the beamline design have been provided to reduce radiation levels external to the beamline enclosures during normal operation to <0.05 mrem/h and as low as reasonably achievable. Assuming occupancy of 2000 hours per year, this will reduce annual dose limit to the beamline scientists to 100 mrem or less.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Shielding Design of Gantry 3 - Paper 104

The proton therapy complex at PSI will be extended with a third irradiation facility, Gantry 3. This new Gantry is being built in the south-west area of the experimental hall of the High Intensity Proton Accelerator (HIPA) complex at PSI. Originally, it was planned to restrict the operation of Gantry 3 to 180 deg. by hardware means, but due to new considerations, the Gantry will be able to be moved in the full 360 deg. field. This change requires the redesign and reinforcement of the too weak shielding in the north and east directions. Additionally, the isocenter has been fixed, thus allowing for the exact calculation of distances, angles and effective shielding thicknesses in order to determine the dose rates more accurately. For these calculations a fast and simple semi-empirical analytical formula and the more time consuming, but also more sophisticated best estimate code MCNPX 2.7.0 have been used. The two methods used for the calculations of the dose rates are in good agreement. Generally, the analytical method provides the results instantaneously, but predicts higher dose rate values of a factor 2-3 larger than the Monte-Carlo particle transport code MCNPX. Thus, MCNPX should be used to verify the final design of the shielding, including additional details in the simulation model (e.g. ventilation shafts) which have weakening effect on the shielding. Such influences are hard to quantify analytically. The analytical method fails when the geometry becomes complex, i.e. when it is difficult to determine the effective length of the shielding; in the case of position 10 the shielding effect of the inner wall is difficult to quantify. Due to the change of the specification of the Gantry, the shielding was reinforced at the north and east sides, and the HC-layer was extended in front of the control room. The dose rates are acceptable with the new shielding layout. A detailed dose rate mapping is planned in the commissioning phase of Gantry 3 to verify the simulation results and to identify any remaining weak spots of the shielding. (authors)

43 PARTICLE ACCELERATORS↗
NASA NTRS1975

Weight optimization methods in space radiation shield design

An empirical relation between proton range and material density is used to examine relations between shield weight, geometry, and material composition for shielding against a space proton environment. The optimum material resulting in minimum shield weight usually lies at the extremes of either the lightest or heaviest materials. Aluminum, which has special prominence in the space program, appears universally suboptimal as a radiation shielding material. Assuming square-box geometry (rectangular prisms with two square faces), the optimum shape for the shielded objects is found to be a cube, although moderate deviations from a cube result in only a small weight penalty.

Wilson, J. W.↗
NASA NTRS1977

Status of the Electroforming Shield Design (ESD) project

The utilization of a digital computer to augment electrodeposition/electroforming processes in which nonconducting shielding controls local cathodic current distribution is reported. The primary underlying philosophy of the physics of electrodeposition was presented. The technical approach taken to analytically simulate electrolytic tank variables was also included. A FORTRAN computer program has been developed and implemented. The program utilized finite element techniques and electrostatic theory to simulate electropotential fields and ionic transport.

Fletcher, R. E.↗
NASA NTRS1992

Hypervelocity impact simulation for micrometeorite and debris shield design

A new capability has been developed for direct computer simulation of hypervelocity impacts on multi-plate orbital debris shields, for combinations of low shield thickness and wide shield spacing which place extreme demands on conventional Eulerian analysis techniques. The modeling methodology represents a novel approach to debris cloud dynamics simulation, a problem of long term interest in the design of space structures. Software implementation of the modeling methodology provides a new design tool for engineering analysis of proposed orbital debris protection systems.

Fahrenthold, Eric P.↗