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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 1,549 records · Page 86
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Exploring communication techniques across a wide spectrum of groups - 15105

Communication about radionuclide and nuclear waste is one factor in facilitating decisions regarding environmental issues and energy solutions. However, the decision process involves many people with a variety of perceptions that have been formed throughout many years. This paper describes various communication techniques across a spectrum of stakeholders from the general public, students, first responders, analysts, and decisions makers. Techniques include dose assessment tools, assessment training, preparing first responders to confront potential radiological/nuclear situations, web multimedia information, ongoing Department of Energy (DOE) education projects, public talks and presentations, and National Environmental Policy Act (NEPA) participation. Issues are identified concerning perception including units, background radiation, effects of environmental levels of radiation, potential approaches to energy literacy, and risk comparison. These various communication techniques across a spectrum of stakeholders are evaluated with feedback and use statistics concerning aspects of strategies, challenges, and common perceptions. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Effect of Radiation from Low-Level Radioactive Waste Leachate on Antioxidant Depletion in HDPE Geo-membrane - 16087

Low-level radioactive waste (LLW) and mixed waste (MW) disposal facilities in the US are required to have a service life in excess of 1000 yr. Understanding the rate of degradation of high-density polyethylene (HDPE) geo-membranes (GMs) used in LLW and MW facilities is necessary to assess their service life when conducting a performance assessment for a disposal facility. In LLW and MW disposal facilities, GMs may be exposed to radionuclides that may accelerate antioxidant depletion and degradation. This paper evaluates how radiation dosage affects antioxidant depletion in HDPE GMs and makes inferences regarding the impact of radiation on GM service life. Specimens of 0.04-mm-, 0.1-mm-, and 2-mm-thick HDPE GMs were exposed to a sealed source of Am-241 to simulate alpha radiation from LLW leachate (e.g., uranium). The specimens were exposed to the sealed source for 1-50 h, followed by oxidative induction time (OIT) testing to determine depletion of antioxidants in response to exposure. Penetration of alpha particles in the HDPE GM exposed to the sealed source was evaluated with the program Geometry And Tracking (GEANT4). The GEANT4 modeling indicates that physical dose deposition for alpha particles largely occurs on the superficial layers and decreased monotonically with depth to a negligible dose (∼ 28 μm). For a 2-mm-thick HDPE GM, there was no change in OIT after exposure, whereas in much thinner GMs (e.g., 0.04 mm), significant antioxidant depletion occurred after exposure, reflecting the shallow penetration of alpha radiation at the surface of HDPE GM. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Effects of Gamma Radiation on Cementitious Materials in Repository Environment - 16300

Cementitious materials are widely used in the management of radioactive waste and have to perform as required for the period of service life of the installation. In order to assess the long term durability of cement paste in a deep borehole for radioactive wastes, specimens were cast in laboratory and exposed to a gamma radiation field. The effects of the radiation in the specimens were evaluated by X-Ray Diffraction, as changes observed in the mineralogy and microstructure of the material after irradiation doses varying between 0 (without radiation) and 10 MGy. It was observed that the specimens exposed to higher doses of gamma radiation (up to 3 MGy) presented differences between surface and core, when compared with the samples with no radiation or exposed to low doses. These results are important to model the behavior of cementitious materials under the conditions expected in a borehole repository and to provide data for the safety assessment of the installation. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Time-dependent collisional radiative modeling of tungsten in the magnetic sheath for erosion diagnosis

Abstract Tungsten is the material of choice for the divertors in ITER, SPARC and future fusion reactors. Accurate diagnosis of tungsten erosion and migration is important for first wall life time, slag production and core performance. The addition of a magnetic presheath requires time-dependent collisional radiative effects to be included for accurate neutral tungsten collisional radiative modeling. Gross erosion measurements could be modified by a factor of 10 due to the inclusion of time-dependent effects for ITER relevant divertor conditions. A simple sputtering model and sheath density model are developed to investigate time-dependent collisional radiative effects. Neutral tungsten spectral lines populated from different metastable levels depend on model parameters leading to potential spectroscopic diagnostics of plasma parameters. Electron temperatures inferred from spectroscopic line ratios are in agreement with Langmuir probe measurements in the Compact Toroidal Hybrid.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1961

Effects of Ionizing Radiation on Solid Rocket Motor Components

Problems which the solid propellant rocket engineer will encounter in designing for long-term storage in a radiation environment are discussed. A summary of present knowledge of the radiation environment is given. Mechanisms of radiation degradation and its effects on tensile properties of propellant binders are discussed qualitatively. Data from a program of irradiation of several propellants is presented. Properties of two of the propellants were changed significantly by doses of the order of 4 x 10(exp 6) rads.

RADIATION↗
DOE OSTI2020

Nuclear Weapon Medical Effects

Presentation Overview: Nuclear Weapon Medical Effects; Psychological Effects; Contamination; Lethal Dose; Acute Radiation Syndromes; Chronic Radiation Effects; Thermal Injuries; Blast Injuries

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
NASA NTRS1991

The effect of surface radiation on flame spread in a quiescent, microgravity environment

In most theories of laminar flame spread over solid combustibles, radiation is neglected. However, when gas motion is completely absent, which may occur in the quiescent, microgravity environment of a spacecraft, the importance of radiation compared to convection is enhanced. Here, a theoretical model is developed of flame spread over a thin solid fuel into an opposing flow of oxidizer, the opposing flow being present in the quiescent environment in flame-fixed coordinates, including the effects of radiative heat transfer from the fuel surface. Numerical solutions to the conservation equations in the gas and the solid phase that describe the spreading flame are presented for a variety of ambient conditions and surface emittances. When surface radiation is significant, the solid surface acts as a heat sink, causing the flame to cool, shrink in size, and spread more slowly. Better agreement with experiment for net heat transfer to the surface is obtained when surface radiation is included. For low ambient oxygen levels, radiative effects lead to flame extinction. A radiation/conduction parameter is identified that adequately describes the importance of surface radiation.

Bhattacharjee, S.↗