Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Nuclear radiation”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Effects of Nuclear Interactions in Space Radiation Transport

Space radiation transport codes have been developed to calculate radiation effects behind materials in human missions to the Moon, Mars or beyond. We study how nuclear fragmentation processes affect predictions from such radiation transport codes. In particular, we investigate the effects of fragmentation cross sections at different energies on fluxes, dose and dose-equivalent from galactic cosmic rays behind typical shielding materials.

Lin, Zi-Wei↗
NASA NTRS2005

Effects of Nuclear Interactions in Space Radiation Transport

Space radiation transport codes have been developed to calculate radiation effects behind materials in human mission to the Moon, Mars or beyond. We study how nuclear fragmentation processes affect predictions from such radiation transport codes. In particular, we investigate the effects of fragmentation cross sections at different energies on fluxes, dose and dose-equivalent from galactic cosmic rays behind typical shielding materials.

Lin, Zi-Wei↗
NASA NTRS2014

Lightweight Radiator for in Space Nuclear Electric Propulsion

Nuclear electric propulsion (NEP) is a promising option for high‐speed in‐space travel due to the high energy density of nuclear fission power sources and efficient electric thrusters. Advanced power conversion technologies may require high operating temperatures and would benefit from lightweight radiator materials. Radiator performance dictates power output for nuclear electric propulsion systems. Game‐changing propulsion systems are often enabled by novel designs using advanced materials. Pitch‐based carbon fiber materials have the potential to offer significant improvements in operating temperature, thermal conductivity, and mass. These properties combine to allow advances in operational efficiency and high temperature feasibility. An effort at the NASA Marshall Space Flight Center to show that woven high thermal conductivity carbon fiber mats can be used to replace standard metal and composite radiator fins to dissipate waste heat from NEP systems is ongoing. The goals of this effort are to demonstrate a proof of concept, to show that a significant improvement of specific power (power/mass) can be achieved, and to develop a thermal model with predictive capabilities making use of constrained input parameter space. A description of this effort is presented.

Craven, Paul↗
NASA NTRS2011

Review of Nuclear Physics Experiments for Space Radiation

Human space flight requires protecting astronauts from the harmful effects of space radiation. The availability of measured nuclear cross section data needed for these studies is reviewed in the present paper. The energy range of interest for radiation protection is approximately 100 MeV/n to 10 GeV/n. The majority of data are for projectile fragmentation partial and total cross sections, including both charge changing and isotopic cross sections. The cross section data are organized into categories which include charge changing, elemental, isotopic for total, single and double differential with respect to momentum, energy and angle. Gaps in the data relevant to space radiation protection are discussed and recommendations for future experiments are made.

Norbury, John W.↗
NASA NTRS1992

Infrared emission in Seyfert 2 galaxies - Reprocessed radiation from a dusty torus?

New and existing data for a sample of nine Seyfert 2 galaxies with known 'ionization cones' are combined in order to test whether collimation results from shadowing of radiation from a small isotropic nuclear source by a thick dusty torus. The number of ionizing photons emitted by the compact nucleus is calculated from the emission-line ratios measured for gas within the cones. On the assumption that this compact nuclear source radiates isotropically, the optical-UV power incident on the torus, which is expected to be reradiated in the IR, is determined. It is found that the observed IRAS luminosities are consistent with the torus model in eight of the nine objects with sufficient data to perform the calculation. It is concluded that the data are generally consistent with collimation and reradiation by a dusty torus.

Storchi-Bergmann, Thaisa↗
NASA NTRS1973

Nuclear Science Symposium, 19th, and Nuclear Power Systems Symposium, 4th, Miami, Fla., December 6-8, 1972, Proceedings.

Major topics covered include radiation monitoring instrumentation, nuclear circuits and systems, biomedical applications of nuclear radiation in diagnosis and therapy, plasma research for fusion power, reactor control and instrumentation, nuclear power standards, and applications of digital computers in nuclear power plants. Systems and devices for space applications are described, including the Apollo alpha spectrometer, a position sensitive detection system for UV and X-ray photons, a 4500-volt electron multiplier bias supply for satellite use, spark chamber systems, proportional counters, and other devices. Individual items are announced in this issue.

Source record↗
NASA NTRS1992

Radiation enhanced dissociation of hydrogen in nuclear rockets

The effect of radiation-induced dissociation of hydrogen gas in nuclear rockets is studied. The dissociation degree is obtained by solving rate equations, which include the fast-ion induced dissociation and ionization of atomic and molecular hydrogens. Analytical formulas are used to estimate a change in the viscosity and the specific impulse. It was found that the fast-ion induced dissociation plays an important role in enhancing the specific impulse for nuclear rocket concepts using hydrogen gas at low pressures (less than 0.1 MPa) and low temperatures (less than 3000 K). It is also shown that the specific impulse is enhanced by mixing helium-3, lithium-6, boron-10, or uranium-235 with hydrogen.

Watanabe, Yoichi↗
DOE OSTI2022

Nuclear Remote System Design: Radiation and Electronics

Idaho National Laboratory has unique opportunities to examine fuels, materials, and experiment inside of the available radiological hot cells. Due to the uninhabitable nature of a hot cell environment, everything done inside of the hot cell is operated remotely. Remote operations are optimized by Nuclear Remote System Design (NRSD). NRSD is the designing, altering, or configuring of structures, items, and systems that will be placed into radiological environments.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1972

The influence of radiation shielding on reusable nuclear shuttle design

Alternate reusable nuclear shuttle configurations were synthesized and evaluated. Particular attention was given to design factors which reduced tank exposure to direct and scattered radiation, increased payload-engine separation, and improved self-shielding by the LH2 propellant. The most attractive RNS concept in terms of cost effectiveness consists of a single conical aft bulkhead tank with a high fineness ratio. Launch is accomplished by the INT-21 with the tank positioned in the inverted attitude. The NERVA engine is delivered to orbit separately where final stage assembly and checkout are accomplished. This approach is consistent with NERVA definition criteria and required operating procedures to support an economically viable nuclear shuttle transportation program in the post-1980 period.

Littman, T. M.↗
DOE OSTI2020

Radiation Chemistry Research for Improved Nuclear Fuel Cycles

Nuclear energy is a key component of a global, low-carbon energy future. One of the challenges facing large-scale deployment of nuclear power is the long-term disposition of used nuclear fuel. Due to the political and technical challenges of siting deep geologic storage facilities, reprocessing of used nuclear fuel is desirable to reduce the total volume and decay heat of waste requiring long-term storage, enabling efficient usage of geologic storage repositories. However nuclear fuel reprocessing is complicated by intense multi-component radiation fields that degrade solvent systems that are used for this purpose. Resulting radiolytic degradation can result in reduced performance over time, and generation of additional waste. Thus, an understanding of the radiation-induced chemistry of these reprocessing solvent systems is crucial to for the development of new, radiation-resistant processes for efficiently treating used nuclear fuel. Controlled irradiation experiments combined with high-performance chromatography and mass spectrometry have provided comprehensive knowledge of radiolytic degradation pathways and kinetics, which is needed to predict the effect of radiation-induced chemistry on the performance of the nuclear fuel reprocessing technology. This talk will give an overview of recent progress in research on the radiation chemistry of fuel reprocessing molecules conducted by the Idaho National Laboratory Center for Radiation Chemistry Research (CR2) in conjunction with the Molecular Mass Spectrometry and Chromatography group.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS2010

A Biomathematical Model of Lymphopoiesis and Its Application to Acute and Chronic Irradiation Assessment

After the events of September 11, 2001, there is an increasing concern of the occurrence of radiological terrorism that may result in significant casualties in densely populated areas. Much effort has been made to establish various biomarkers to rapidly assess radiation dose in mass-casualty and population-monitoring scenarios, which are demanded for effective medical management and treatment of the exposed victims. Among these the count of lymphocytes in peripheral blood and their depletion kinetics are the most important early indicators of the severity of the radiation injury. In this study, we examine a biomathematical model of lymphopoiesis which has been successfully utilized to simulate and interpret experimental data of acute and chronic irradiations on rodents [1]. With revised parameters for humans, we find this model can reproduce several sets of clinical lymphocyte data of accident victims over a wide range of absorbed doses. In addition, the absolute lymphocyte counts and the depletion rate constants calculated by this model also show good correlation with the Guskova formula and the Goans model, the two empirical tools which have been widely recognized for early estimation of the exposed dose after radiation accidents [2]. We also use the model to analyze the hematological data of the Techa River residents which were exposed to chronic low-dose irradiation during 1950-1956 [3]. This model can serve as a computational tool in radiation accident management, military operations involving nuclear warfare, radiation therapy, and space radiation risk assessment.

Hu, Shaowen↗
NASA NTRS1978

Quiet time observations of equatorially trapped megaelectronvolt radiation belt ions with nuclear charge Z greater than or equal to 4

Data from the equatorial satellite Explorer 45 were used to study ion fluxes during the geomagnetically quiescent period June 1-15, 1972. A heavy-ion solid-state ion detector system obtained count rates close to the equatorial plane in the energy passband 1.82-4.8 MeV per ion during a single satellite pass through the radiation belts. Fluxes of these ions are interpreted as oxygen ions and are found to maximize in the L shell range 3-3.5 with peak equatorially mirroring flux of 0.38 ions/(sq cm s sr keV). This peak is not as sharply confined in L shell as is the helium ion peak.

Spjeldvik, W. N.↗
DOE OSTI2026

Evaluation of Radiation Transport Through a Nuclear-Grade Sandwich Composite

The development and deployment of microreactors are often synonymous with their transportability; however, designing a shield which is appropriate for both transportation and operations is challenging. A recent approach is the use of composite style shield which combines the reactor pressure vessel and biological shielding into a single unit to enhance the shields effectiveness without degrading the structural properties. To assess the viability of a nuclear grade sandwich composite (NGSC), and understanding of how radiation transports through the shield needs to be understood to select the appropriate materials. This work examines a two-layered NGSC of varying thicknesses with two primary shielding materials (tungsten-tetraboride cermet and boron carbide). To assess the NGSC, quantities of interest including neutron attenuation, photon attenuation, energy deposition, displacements per atom, helium generation, and dose are examined. Altogether, it is found that a combination of both tungsten-tetraboride and boron carbide are necessary to act as an appropriate shield, where the order in which these materials are place in the composite are important to their effectiveness.

22 - GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS2005

How Space Radiation Risk from Galactic Cosmic Rays at the International Space Station Relates to Nuclear Cross Sections

Space radiation risk to astronauts is a major obstacle for long term human space explorations. Space radiation transport codes have thus been developed to evaluate radiation effects at the International Space Station (ISS) and in missions to the Moon or Mars. We study how nuclear fragmentation processes in such radiation transport affect predictions on the radiation risk from galactic cosmic rays. Taking into account effects of the geomagnetic field on the cosmic ray spectra, we investigate the effects of fragmentation cross sections at different energies on the radiation risk (represented by dose-equivalent) from galactic cosmic rays behind typical spacecraft materials. These results tell us how the radiation risk at the ISS is related to nuclear cross sections at different energies, and consequently how to most efficiently reduce the physical uncertainty in our predictions on the radiation risk at the ISS.

Lin, Zi-Wei↗