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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Coupling a Supercritical Carbon Dioxide Brayton Cycle to a Helium-Cooled Reactor.

This report outlines the thermodynamics of a supercritical carbon dioxide (sCO 2 ) recompression closed Brayton cycle (RCBC) coupled to a Helium-cooled nuclear reactor. The baseline reactor design for the study is the AREVA High Temperature Gas-Cooled Reactor (HTGR). Using the AREVA HTGR nominal operating parameters, an initial thermodynamic study was performed using Sandia's deterministic RCBC analysis program. Utilizing the output of the RCBC thermodynamic analysis, preliminary values of reactor power and of Helium flow rate through the reactor were calculated in Sandia's HelCO 2 code. Some research regarding materials requirements was then conducted to determine aspects of corrosion related to both Helium and to sCO 2 , as well as some mechanical considerations for pressures and temperatures that will be seen by the piping and other components. This analysis resulted in a list of materials-related research items that need to be conducted in the future. A short assessment of dry heat rejection advantages of sCO 2 > Brayton cycles was also included. This assessment lists some items that should be investigated in the future to better understand how sCO 2 Brayton cycles and nuclear can maximally contribute to optimizing the water efficiency of carbon free power generation

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2018

Heat Storage Options for Sodium, Salt and Helium Cooled Reactors to Enable Variable Electricity to the Grid and Heat to Industry with Base-Load Reactor Operations

Electricity markets are changing rapidly because of (1) the addition of wind and solar and (2) the goal of a low-carbon electricity grid. These changes result in times of high electricity prices and very low or negative electricity prices. California has seen its first month where more than 20% of the time (mid-day) the wholesale price of electricity was zero or negative. This creates large incentives for coupling heat storage to advanced reactors to enable variable electricity and industrial-heat output (to maximize revenue) while the reactor operates at base load (minimize cost). Recent studies have examined coupling various types of heat storage to Rankine and Brayton power cycles. However, there has been little examination of heat-storage options between (1) the reactor and (2) the power-conversion system or industrial customer. Heat-storage systems can be incorporated into sodium , helium-, and salt-cooled reactors. Salt-cooled reactors include the fluoride-salt-cooled high-temperature reactor (FHR) with its solid fuel and clean coolant and the molten salt reactor (MSR) with its fuel dissolved in the salt. For sodium and salt reactors, it is assumed that a heat-storage system would be in the secondary loop between the reactor and power cycle. For helium-cooled reactors, heat storage can be in the primary or secondary loop. This report is a first look at the rational and the heat storage options for deploying gigawatt-watt hour heat-storage systems with GenIV reactors. Economics and safety are the primary selection criteria. The leading heat-storage candidate for sodium-cooled systems (a low-pressure secondary system with small temperature drop across the reactor core) is sodium coolant stored in large steel tanks, with the coolant transferring heat in channels. The design minimizes sodium volume in the storage and, thus, the risks and costs associated with sodium. For helium systems (high-pressure with large temperature drop across the core), the leading heat storage options are (1) varying the temperature of the reactor core, (2) steel or alumina firebrick in a secondary pressure vessel and (3) nitrate or hot-rock/firebrick at atmospheric pressure. For salt systems (low pressure, high temperatures, and small temperature drop across the reactor core) the leading heat-storage systems are secondary salts. In each case, options are identified and questions to be addressed are identified. In some cases there is a strong coupling between the heat-storage technology and the power cycle. The leading sodium heat-storage technology may imply changes in the power cycle. High-temperature salt systems couple efficiency to Brayton power cycles that may create large incentives for the heat storage to remain within the power cycle rather than in any intermediate heat transfer loop.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2022

PDC Modifications for Analysis of Gas-Cooled Reactors with Direct Helium Brayton Cycle

Capabilities of the Plant Dynamics Code (PDC) have been extended to allow steady-state and transient simulation of graphite-cooled reactors with direct helium Brayton cycle. On the cycle side, the most significant code modification is the addition of helium properties, in the format required by the code’s equations. Since the code was already formulated to handle more complex real gas properties, adding helium as working fluid that behaves like ideal gas was fairly straightforward. A reactor module was added to PDC to simulate a reactor cooled by the working fluid of the Brayton cycle. Two options are supported: channel type, typical for graphite gas-cooled reactors, and pin type, typical for light-water and liquid metal-cooled reactors. The reactor module is an extension of the electrical heater model and simulates heat deposition in the fuel and transfer of this heat from the fuel to the coolant through the matrix and tube materials. The new reactor module becomes the third option in PDC for modeling heat addition to the cycle, besides previously modeled heat addition heat exchanger and electrical heater. In addition to those changes, other minor code modifications and improvements were introduced during the work of expanding PDC to modeling of gas-cooled reactors. These modifications are summarized in the last chapter of this report.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2023

Numerical Analysis and Flow Induced Vibration Studies in Pressurized Helium Gas Cooling Channels

Los Alamos National Laboratory (LANL) is working with NorthStar Medical Radioisotopes (NMR) on their efforts to produce Mo-99 from the irradiation of Mo-100 targets. The NMR target consists of an Inconel window that allows the electron beam to penetrate and irradiate a stack of Mo-100 discs. The irradiation process generates large amounts of heat and is cooled using pressurized helium gas flowing at 400 g/s. LANL provides both numerical analysis support and experimental support. Computational fluid dynamics (CFD) simulations for both 300 g/s and 400 g/s are performed on the NMR target to analyze the helium flow through the NMR system. The pressure drop, the mass flow rate through each of the disc and window channels and the force applied on the first disc are some of the quantities estimated using CFD. These results will be combined with Monte Carlo N-Particle (MCNP) estimates of heat flux into the system from the electron beam to perform conjugate heat transfer analysis (CHT). The experiments presented in this report focus on the effect of the flow induced vibrations from helium flowing through the coolant gaps between the discs. There is concern that the flow induced vibrations may lead to excessive mass loss of the enriched Mo-100 discs, and the goal would be to mitigate the mass loss. This work presents benchtop tests of flow through a subset of the target stack which involves high speed imaging and displacement measurements used to estimate disc vibration, as well as mass loss.

42 ENGINEERING↗
DOE OSTI2024

Analysis of pressure test results of tube fittings for the potential application in cryo systems for helium leak rate reduction

Due to the nature of Helium, it is notoriously difficult to maintain a closed system without experiencing helium inventory loss through leakage in large tubing and piping runs. There are two standard fitting options readily available for piping and tubing assemblies, welded fittings or Swagelok ® . Welding is the best option for leak rate reduction, but more costly than Swagelok ® . A new style of fitting has come to the attention of BNL C-AD Cryo group, and a pressure test and leak rate analysis were performed to evaluate the viability of incorporating this new style fitting into current engineering design of warm helium tubing runs for the purpose of leak rate reduction.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Evaluation of Getters for Helium Purification

• Helium-3 is a vital commodity in both medical and defense applications • Ultra-low cryogenic coolant (MRI imaging, etc.) • Neutron detectors • Being investigated as possible fusion fuel • Managed and distributed by DOE-OS • New PDRD project exploring helium isotope separation • Limited supply • Only available from tritium decay • Prohibitively difficult to separate from helium-4 • SRS Tritium Facility provides a steady source

Angelette, Lucas M.↗
DOE OSTI2019

Effect of helium on dispersoid evolution under self-ion irradiation in a dual-phase 12Cr oxide-dispersion-strengthened alloy

As one candidate alloy for future Generation IV and fusion reactors, a dual-phase 12Cr oxide-dispersion-strengthened (ODS) alloy was developed for high temperature strength and creep resistance and has shown good void swelling resistance under high damage self-ion irradiation at high temperature. However, the effect of helium and its combination with radiation damage on oxide dispersoid stability needs to be investigated. In this study, 120 keV energy helium was preloaded into specimens at doses of 1 × 10 15 and 1 × 10 16 ions/cm 2 at room temperature, and 3.5 MeV Fe self-ions were sequentially implanted to reach 100 peak displacement-per-atom at 475 °C. He implantation alone in the control sample did not affect the dispersoid morphology. After Fe ion irradiation, a dramatic increase in density of coherent oxide dispersoids was observed at low He dose, but no such increase was observed at high He dose. The study suggests that helium bubbles act as sinks for nucleation of coherent oxide dispersoids, but dispersoid growth may become difficult if too many sinks are introduced, suggesting that a critical mass of trapping is required for stable dispersoid growth.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Helium reionization simulations. I. Modeling quasars as radiation sources

We introduce a new project to understand helium reionization using fully coupled N-body, hydrodynamics, and radiative transfer simulations. This project aims to capture correctly the thermal history of the intergalactic medium as a result of reionization and make predictions about the Lyα forest and baryon temperature–density relation. The dominant sources of radiation for this transition are quasars, so modeling the source population accurately is very important for making reliable predictions. In this first paper, we present a new method for populating dark matter halos with quasars. Our set of quasar models includes two different light curves, a lightbulb (simple on/off) and symmetric exponential model, and luminosity-dependent quasar lifetimes. Our method self-consistently reproduces an input quasar luminosity function given a halo catalog from an N-body simulation, and propagates quasars through the merger history of halo hosts. After calibrating quasar clustering using measurements from the Baryon Oscillation Spectroscopic Survey, we find that the characteristic mass of quasar hosts is M{sub h}∼2.5×10{sup 12} h{sup −1} M{sub ⊙} for the lightbulb model, and M{sub h}∼2.3×10{sup 12} h{sup −1} M{sub ⊙} for the exponential model. In the latter model, the peak quasar luminosity for a given halo mass is larger than that in the former, typically by a factor of 1.5–2. The effective lifetime for quasars in the lightbulb model is 59 Myr, and in the exponential case, the effective time constant is about 15 Myr. We include semi-analytic calculations of helium reionization, and discuss how to include these quasars as sources of ionizing radiation for full hydrodynamics with radiative transfer simulations in order to study helium reionization.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Helium recovery system at IB3A

The growing demand for sustainable cryogenic operations at Fermilab has underscored the need to improve helium management, particularly at the Industrial Building 3A (IB3A) test facility. IB3A characterizes and tests superconductors, cables, and coils for projects such as the HL-LHC AUP and Mu2e, yet currently relies on 500 L Dewars whose boil-off is vented to atmosphere, wasting a critical, non-renewable resource and increasing the cost of testing. A project is therefore under way to link IB3A to an existing purification and liquefaction station in a neighboring building through a dedicated pipeline. Captured helium will be transferred, purified, reliquefied, and returned for reuse, cutting losses and operating costs. This paper details the first two project phases: "Design and Engineering" and "Procurement and Installation." The design phase finalizes pipeline specifications, establishes flow-control requirements, and resolves integration challenges with existing cryogenic infrastructure. The procurement and installation phase covers material sourcing, pipeline construction, and deployment of control and monitoring systems to assure reliable, efficient operation. Key technical hurdles-route optimization, pressure drop mitigation, and interface compatibility-are discussed alongside implemented solutions. Implementing the pipeline and upgrading IB3A will dramatically reduce helium consumption and therefore testing cost, strengthening Fermilab's capacity to support frontier science far into the future.

Porwisiak, D. [Fermilab; Wroclaw Tech. U.]↗
NASA NTRS1963

Local Heat-Transfer Measurements for Forced Convection of Hydrogen and Helium at Surface Temperatures Up to 5600 Deg R

Local values of heat-transfer coefficients and average friction coefficients were measured experimentally for helium and hydrogen gas flowing through an electrically heated tungsten tube with a length-diameter ratio of 77 for the following range of conditions: local surface temperatures up to 5600° R, local Reynolds number from 7600 to,39,500, local ratios of surface-to-bulk gas temperature up to 5.6, and heat flux up to 1,700,000 Btu per hour per square foot. A comparison of local heat-transfer coefficients for helium and hydrogen gas is made for several types of wall temperature distribution, which determines whether the data can be correlated by a Dittus-Boelter type equation. A wall temperature distribution for hydrogen is compared with one for helium and found to be essentially the same; this result demonstrates that q dissociation of hydrogen at the tube wall for wall temperatures up to 5200O R has little or no effect on the wall temperature distribution.

Maynard F Taylor↗
NASA NTRS1967

Portable detector set discloses helium leak rates

Portable helium detector measuring helium leak rates makes possible the use of the inert gas helium as a tracer. This helps solve safety and contamination problems in detecting leaks in closed fluid systems.

Anderson, G. E.↗
NASA NTRS1972

Multipurpose top for liquid helium Dewar

Multipurpose top was fabricated for liquid helium Dewar flask which guards against flash vaporization of liquid helium and allows boiling temperature of liquid helium to be lowered by reduction of ambient pressure in Dewar flask. Device is rugged and simple, and does not require frequent calibrations or adjustments.

Murphy, R. S.↗
NASA NTRS1971

The cosmic helium abundance

Cosmic helium abundance was studied through the interior structure of young stars, profiles of helium absorption lines in the photospheric spectra of hot young stars, and emission-line spectrum of ionized gas. It is concluded that helium occurred before galaxies were formed. Inconsistencies found in the quasar spectra are briefly mentioned.

Searle, L.↗
NASA NTRS1971

Thermodynamic properties of hydrogen-helium plasmas

The thermodynamic properties of an atomic hydrogen-helium plasma are calculated and tabulated for temperatures from 10,000 to 100,000 K as a function of the mass fraction ratio of atomic hydrogen. The tabulation is for densities from 10 to the minus 10th power to 10 to the minus 6th power gm/cu cm and for hydrogen mass fraction ratios of 0, 0.333, 0.600, 0.800, and 1.0, which correspond to pure helium, 50 percent hydrogen per unit volume, 75 percent hydrogen per unit volume, 89 percent hydrogen per unit volume, and pure hydrogen plasmas, respectively. From an appended computer program, calculations can be made at other densities and mass fractions. The program output agrees well with previous thermodynamic property calculations for limiting cases of pure hydrogen and pure helium plasmas.

Nelson, H. F.↗
NASA NTRS1971

Effect of two types of helium circulators on the performance of a subsonic nuclear powered airplane

Two types of helium circulators are analytically compared on the bases of their influence on airplane payload and on propulsion system variables. One type of circulator is driven by the turbofan engines with power takeoff shafting while the other, a turbocirculator, is powered by a turbine placed in the helium loop between the nuclear reactor and the helium-to-air heat exchangers inside the engines. Typical results show that the turbocirculator yields more payload for circulator efficiencies greater than 0.82. Optimum engine and heat exchanger temperatures and pressures are significantly lower in the turbocirculator case compared to the engine-driven circulator scheme.

Strack, W. C.↗
NASA NTRS1972

Cosmic ray proton and helium spectra above 50 GeV

Differential energy spectra of cosmic ray protons and helium nuclei were measured by an ionization spectrometer flown at balloon altitudes. The energy range extended from 50 GeV to above 1000 GeV. The observed differential intensities can be represented with power law spectra with a slope of -2.75 + or - 0.03 for protons and of -2.77 + or - 0.55 for helium nuclei. The proton to helium ratio is equal to 26 + or - 3 at 40 GeV/nuc and is constant within errors up to 400 GeV/nuc.

Ryan, M. J.↗
NASA NTRS1971

The evolution of hydrogen-helium stars.

Investigation of the premain sequence evolution and the main sequence evolution of stars of 5, 10, 20, 30, 100, and 200 solar masses. Normal stars in this entire mass range normally convert hydrogen into helium by the CN-cycle on the main sequence. The present hydrogen-helium stars of 5 and 10 solar masses must reach higher central temperatures in order to convert hydrogen to helium by the proton-proton chains. Consequently, the mean densities in the stars are greater, and the surface temperatures are higher than in normal stars. In the stars of 20 solar masses and larger, the proton-proton chains do not succeed in supplying the necessary luminosity of the stars by the time the contraction has produced a central temperature near 10 to the 8th K. At that point triple-alpha reactions generate small amounts of C12, which then acts as a catalyst in the CN-cycle, the rate of which is then limited by the beta-decays occurring within the cycle. During the evolution of these more massive stars, the central temperature remains in the vicinity of 10 to the 8th K, and the surface temperature on the main sequence approaches 100,000.

Ezer, D.↗
NASA NTRS1972

Helium in the topside Venus ionosphere

The quantity of helium in the Venus atmosphere is estimated from an examination of the measured ionization profiles. The amount of helium necessary to give agreement between the computed and experimental results is approximately 4 x 10 to the 8th power/cucm at 140 km. When an eddy diffusion coefficient of 1,000,000 sq cm/see is used, the atmospheric helium mixing ratio is found to be 0.0006; a value nearly ten times that for earth.

Herman, J. R.↗