Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “radioactive decay data”

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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Radioactivity in the galactic plane

The paper reports the detection of a large concentration of interstellar radioactivity during balloon-altitude measurements of gamma-ray energy spectra in the band between 0.02 and 12.27 MeV from galactic and extragalactic sources. Enhanced counting rates were observed in three directions towards the plane of the Galaxy; a power-law energy spectrum is computed for one of these directions (designated B 10). A large statistical deviation from the power law in a 1.0-FWHM interval centered near 1.16 MeV is discussed, and the existence of a nuclear gamma-ray line at 1.15 MeV in B 10 is postulated. It is suggested that Ca-44, which emits gamma radiation at 1.156 MeV following the decay of radioactive Sc-44, is a likely candidate for this line, noting that Sc-44 arises from Ti-44 according to explosive models of supernova nucleosynthesis. The 1.16-MeV line flux inferred from the present data is shown to equal the predicted flux for a supernova at a distance of approximately 3 kpc and an age not exceeding about 100 years.

Walraven, G. D.↗
NASA NTRS1988

Gamma radiation background measurements from Spacelab 2

A Nuclear Radiation Monitor incorporating a NaI(Tl) scintillation detector was flown as part of the verification flight instrumentation on the Spacelab 2 mission, July 29 to August 6, 1985. Gamma-ray spectra were measured with better than 20 s resolution throughout most of the mission in the energy range 0.1 to 30 MeV. Knowledge of the decay characteristics and the geomagnetic dependence of the counting rates enable measurement of the various components of the Spacelab gamma-ray background: prompt secondary radiation, Earth albedo, and delayed induced radioactivity. The status of the data analysis and present relevant examples of typical background behavior are covered.

Paciesas, William S.↗
NASA NTRS1989

Gamma radiation background measurements from Spacelab 2

A Nuclear Radiation Monitor incorporating a NaI(Tl) scintillation detector was flown as part of the verification flight instrumentation on the Spacelab 2 mission, July 29 to August 6, 1985. Gamma-ray spectra were measured with better than 20 s resolution throughout most of the mission in the energy range 0.1 to 30 MeV. Knowledge of the decay characteristics and the geomagnetic dependence of the counting rates enable measurement of the various components of the Spacelab gamma-ray background: prompt secondary radiation, earth albedo, and delayed induced radioactivity. The status of the data analysis and present relevant examples of typical background behavior are covered.

Paciesas, William S.↗
NASA NTRS2017

Cassini Power Subsystem

The electrical output of Cassini’s power system has been decaying consistently as predicted during its 20-year mission between October 1997 and September 2017. The power telemetry data is presented for the entire Cassini mission, including launch, cruise, and Saturn tour, up to the most recent available data. The spacecraft has been powered by three independent Radioisotope Thermoelectric Generators (RTGs) connected in parallel, which were able to generate 882 W at the beginning of the mission shortly after launch. The decrease in power energy output has mainly been driven by the heat reduction of the hot side of the RTGs due to the natural radioactive decay of its heat source plutonium (mostly plutonium-238 [238Pu]), degradation of thermoelectric material performance, and interface degradation.

Carr, Gregory A.↗
NASA NTRS1990

A limit on the production of Ni-56 in a type I supernova

The data from the Gamma-Ray Spectrometer on the Solar Maximum Mission satellite have been searched for evidence of gamma-ray line emission from the decay of Co-56 in the type Ia SN, 1986G. No significant flux at either 847 or 1238 keV, the energies of the two strongest decay lines is found. Based on the data, a 3-sigma upper limit of 0.4 solar masses (D/3 Mpc)-squared on the amount of Ni-56 produced in the explosion is set. This value is consistent with radioactive models of type I light curves. For distances less than 3 Mpc, the limit is inconsistent with most models of SN Ia as thermonuclear explosions of white dwarfs.

Matz, Steven M.↗
NASA NTRS1991

Radioactive satellites - Intact reentry and breakup by debris impact

There is a substantial mass of radioactive material in nuclear reactors or radioisotope thermal generators (RTGs) in orbit about the earth. This paper examines the reentry of intact nuclear fuel cores and RTGs and the fragmentation and subsequent radioactive debris cloud deposition and evolution resulting from the impact of orbital debris upon an orbiting reactor, fuel core, or RTG. To assess the intact reentry, decay rates and a predicted decay date using historical and projected orbital decay data, are estimated. The current NASA debris environment model is utilized to estimate impact rates and debris cloud evolution of a fragmentation event. Results of these analyses are compared and concepts are tendered which would tend to minimize the radiological debris hazard to personnel and structures both on the earth's surface and in low earth orbit.

Anz-Meador, P. D.↗
NASA NTRS1992

Science applications of the Mars Observer gamma ray spectrometer

The Mars Observer gamma ray spectrometer will return data related to the elemental composition of Mars. The instrument has both a gamma ray spectrometer and several neutron detectors. The gamma ray spectrometer will return a spectrum nominally every 20 s from Mars permitting a map of the elemental abundances to be made. The gamma rays are emitted from nuclei involved in radioactive decay, from nuclei formed by capture of a thermal neutron, and from nuclei put in an excited state by a fast-neutron interaction. The gamma rays come from an average depth of the order of a few tens of centimeters. The spectrum will show sharp emission lines whose intensity determines the concentration of the element and whose energy identifies the element. The neutron detectors, using the fact that the orbital velocity of the Mars Observer spacecraft is similar to the velocity of thermal neutrons, determine both the thermal and epithermal neutron flux. By combining the results from both techniques it is possible to map the depth dependence of hydrogen in the upper meter as well. These data permit a variety of Martian geoscience problems to be addressed including the crust and mantle composition, weathering processes, volcanism, and the volatile reservoirs and processes.

Boynton, W. V.↗
DOE OSTI2020

Tritium Aging Effects on Fracture Toughness of Stainless Steel Weldments

The long-term embrittlement effects of tritium and decay helium on the structural properties of stainless steels have been studied for years at Savannah River to provide required data for establishing safe operating conditions and lifetimes of pressure vessels used to contain tritium gas. In this study, the fracture toughness properties of the longest-aged tritium-precharged stainless-steel base metals and weldments tested at Savannah River were measured and compared to earlier results. The fracture toughness values were the lowest recorded here for tritium-exposed stainless steel. As-forged and as-welded specimens were thermally precharging with tritium gas at 34.5 MPa and 623 K, then aged for up to 17 years to buildin decay helium prior to testing. ASTM J-Integral fracture mechanics analyses, transmission electron microscopy (TEM), and small angle neutron scattering (SANS) examinations were conducted to characterize the effects of tritium and its radioactive decay product, helium-3. Results show that the fracture toughness values were reduced to less than 2-4% of the as-forged values for specimens with more than 1300 appm helium from tritium decay. The trend of decreasing fracture toughness values with increasing helium content was consistent with earlier observations, and the data show that Type 304L stainless steel is more resistant to tritium-induced cracking than Type 21-6-9 stainless at similar decay helium levels. The fracture toughness properties of long-aged weldments were also affected, but the reductions were not as severe over time because weldments did not retain as much tritium as did the base metals. TEM observations were used to characterize the effects of decay helium bubbles on the deformation substructures, but nanometer-sized helium bubbles were not easily resolved because of high dislocation densities within the forged microstructures. SANS results are presented that suggest the technique can provide information on decay helium bubble size, spacing, and distribution in these steels.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Classification methodology for tritiated waste requiring interim storage

Fusion machines like the ITER experimental research facility will use tritium as fuel. Therefore, most of the solid radioactive waste will result not only from activation by 14 MeV neutrons, but also from contamination by tritium. As a consequence, optimizing the treatment process for waste containing tritium (tritiated waste) is a major challenge. This paper summarizes the studies conducted in France within the framework of the French national plan for the management of radioactive materials and waste. The paper recommends a reference program for managing this waste based on its sorting, treatment and packaging by the producer. It also recommends setting up a 50-year temporary storage facility to allow for tritium decay and designing future disposal facilities using tritiated radwaste characteristics as input data. This paper first describes this waste program and then details an optimized classification methodology which takes into account tritium decay over a 50-year storage period. The paper also describes a specific application for purely tritiated waste and discusses the set-up expected to be implemented for ITER decommissioning waste (current assumption). Comparison between this optimized approach and other viable detritiation techniques will be drawn. (authors)

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Opacities of singly and doubly ionized neodymium and uranium for kilonova emission modeling

ABSTRACT Even though the electromagnetic counterpart AT2017gfo to the binary neutron star merger GW170817 is powered by the radioactive decay of r-process nuclei, only few tentative identifications of light r-process elements have been made so far. One of the major limitations for the identification of heavy nuclei is incomplete or missing atomic data. While substantial progress has been made on lanthanide atomic data over the last few years, for actinides there has been less emphasis, with the first complete set of opacity data only recently published. We perform atomic structure calculations of neodymium (Z = 60) as well as the corresponding actinide uranium (Z = 92). Using two different codes [flexible atomic code (fac) and hartree–fock-relativistic (hfr)] for the calculation of the atomic data, we investigate the accuracy of the calculated data (energy levels and electric dipole transitions) and their effect on kilonova opacities. For the fac calculations, we optimize the local central potential and the number of included configurations and use a dedicated calibration technique to improve the agreement between theoretical and available experimental atomic energy levels (AELs). For ions with vast amounts of experimental data available, the presented opacities agree quite well with previous estimations. On the other hand, the optimization and calibration method cannot be used for ions with only few available AELs. For these cases, where no experimental nor benchmarked calculations are available, a large spread in the opacities estimated from the atomic data obtained with the various atomic structure codes is observed. We find that the opacity of uranium is almost double the neodymium opacity.

Flörs, A. (ORCID:0000000320242819)↗
DOE OSTI2016

Remote Gamma Ray Spectrum Acquisition

An approach is presented that utilizes networking, hardware, and software components to allow data acquisition from Canberra's Osprey multi-channel analyzer (MCA) detector. The research has allowed researchers to remotely connect to Canberra's ProSpect gamma spectroscopy software and the detector by making use of Windows Server 2012 and a network connection. Gamma rays are ionizing, electromagnetic radiation of high energy and short wavelength. They are produced primarily by radioactive decay. Several undergraduate courses at Texas A and M University-Kingsville focus on teaching students to measure and research gamma rays while in the laboratory. Recent needs have motivated efforts to develop a network solution that allows authorized students and researchers to access the ProSpect software and Osprey MCA detectors remotely from multiple computers connected to the campus network. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

The late-time light curve of the Type Ia supernova SN 2011fe

We present late-time optical R-band imaging data from the Palomar Transient Factory (PTF) for the nearby Type Ia supernova SN 2011fe. The stacked PTF light curve provides densely sampled coverage down to R ≃ 22 mag over 200–620 d past explosion. Combining with literature data, we estimate the pseudo-bolometric light curve for this event from 200 to 1600 d after explosion, and constrain the likely near-infrared (Near-IR) contribution. This light curve shows a smooth decline consistent with radioactive decay, except over ~ 450 to ~ 600 d where the light curve appears to decrease faster than expected based on the radioactive isotopes presumed to be present, before flattening at around 600 d. We model the 200–1600 d pseudo-bolometric light curve with the luminosity generated by the radioactive decay chains of 56 Ni, 57 Ni and 55 Co, and find it is not consistent with models that have full positron trapping and no infrared catastrophe (IRC); some additional energy escape other than optical/near-IR photons is required. However, the light curve is consistent with models that allow for positron escape (reaching 75 per cent by day 500) and/or an IRC (with 85 per cent of the flux emerging in non-optical wavelengths by day 600). The presence of the 57 Ni decay chain is robustly detected, but the 55 Co decay chain is not formally required, with an upper mass limit estimated at 0.014 M ⊙ . The measurement of the 57 Ni/ 56 Ni mass ratio is subject to significant systematic uncertainties, but all of our fits require a high ratio >0.031 (>1.3 in solar abundances).

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Impact of Modular Total Absorption Spectrometer measurements of β decay of fission products on the decay heat and reactor ν ¯ e flux calculation

Here, we report the results of a β-decay study of fission products 86 Br, 89 Kr, 89 Rb, 90 gs Rb, 90m Rb, 90 Kr, 92 Rb, 139 Xe, and 142 Cs performed with the Modular Total Absorption Spectrometer (MTAS) and on-line mass-separated ion beams. These radioactivities were assessed by the Nuclear Energy Agency as having high priority for decay heat analysis during a nuclear fuel cycle. We observe a substantial increase in β feeding to high excited states in all daughter isotopes in comparison to earlier data. This increases the average γ-ray energy emitted by the decay of fission fragments during the first 10 000 s after fission of 235 U and 239 Pu by approximately 2% and 1%, respectively, improving agreement between results of calculations and direct observations. New MTAS results reduce the reference reactor ¯ν e flux used to analyze reactor ¯ν e interaction with detector matter. The reduction determined by the ab initio method for the four nuclear fuel components, 235 U, 238 U, 239 Pu, and 241 Pu, amounts to 0.976, 0.986, 0.983, and 0.984, respectively.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

GRB 171205A: Hypernova and Newborn Neutron Star

GRB 171205A is a low-luminosity, long-duration gamma-ray burst (GRB) associated with SN 2017iuk, a broad-line type Ic supernova (SN). It is consistent with having been formed in the core collapse of a widely separated binary, which we have called the binary-driven hypernova of type III. The core collapse of the CO star forms a newborn NS (νNS) and the SN explosion. Fallback accretion transfers mass and angular momentum to the νNS, here assumed to be born non-rotating. The accretion energy injected into the expanding stellar layers powers the prompt emission. The multiwavelength power-law afterglow is explained by the synchrotron radiation of electrons in the SN ejecta, powered by energy injected by the spinning νNS. We calculate the amount of mass and angular momentum gained by the νNS, as well as the νNS rotational evolution. The νNS spins up to a period of 47 ms, then releases its rotational energy powering the synchrotron emission of the afterglow. The paucity of the νNS spin explains the low-luminosity characteristic and that the optical emission of the SN from the nickel radioactive decay outshines the optical emission from the synchrotron radiation. From the νNS evolution, we infer that the SN explosion had to occur at most 7.36 h before the GRB trigger. Therefore, for the first time, the analysis of the GRB data leads to the time of occurrence of the CO core collapse leading to the SN explosion and the electromagnetic emission of the GRB event.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Thermal Evolution near Heat-Generating Nuclear Waste Canisters Disposed in Horizontal Drillholes

We consider the disposal of spent nuclear fuel and high-level radioactive waste in horizontal holes drilled into deep, low-permeable geologic formations using directional drilling technology. Residual decay heat emanating from these waste forms leads to temperature increases within the drillhole and the surrounding host rock. The spacing of waste canisters and the configuration of the various barrier components within the horizontal drillhole can be designed such that the maximum temperatures remain below limits that are set for each element of the engineered and natural repository system. We present design calculations that examine the thermal evolution around heat-generating waste for a wide range of material properties and disposal configurations. Moreover, we evaluate alternative layouts of a monitoring system to be part of an in situ heater test that helps determine the thermal properties of the as-built repository system. A data-worth analysis is performed to ensure that sufficient information will be collected during the heater test so that subsequent model predictions of the thermal evolution around horizontal deposition holes will reliably estimate the maximum temperatures in the drillhole. The simulations demonstrate that the proposed drillhole disposal strategy can be flexibly designed to ensure dissipation of the heat generated by decaying nuclear waste. Moreover, an in situ heater test can provide the relevant data needed to develop a reliable prediction model of repository performance under as-built conditions.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Total absorption spectroscopy of fission fragments relevant for reactor antineutrino spectra

Here, the accurate determination of reactor antineutrino spectra remains a very active research topic for which new methods of study have emerged in recent years. Indeed, following the long-recognized reactor anomaly (measured antineutrino deficit in short baseline reactor experiments when compared with spectral predictions), the three international reactor neutrino experiments Double Chooz, Daya Bay and Reno have recently demonstrated the existence of spectral distortions in their measurements with respect to the same predictions. These spectral predictions were obtained through the conversion of integral beta-energy spectra obtained at the ILL research reactor. Several studies have shown that the underlying nuclear physics required for the conversion of these spectra into antineutrino spectra is not totally understood. An alternative to such converted spectra is a complementary approach that consists of determining the antineutrino spectrum by means of the measurement and processing of nuclear data. The beta properties of some key fission products suffer from the pandemonium effect which can be circumvented by the use of the Total Absorption Gamma-ray Spectroscopy technique (TAGS). The two main contributors to the Pressurized Water Reactor antineutrino spectrum in the region where the spectral distortion has been observed are 92 Rb and 142 Cs, which have been measured at the radioactive beam facility of the University of Jyvaskyla in two TAGS experiments. We present the results of the analysis of the TAGS measurements of the β-decay properties of 92 Rb along with preliminary results on 142 Cs and report on the measurements already performed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Commissioning of the BRIKEN detector for the measurement of very exotic β -delayed neutron emitters

A new detection system has been installed at the RIKEN Nishina Center (Japan) to investigate decay properties of very neutron-rich nuclei. The setup consists of three main parts: a moderated neutron counter, a detection system sensitive to the implantation and decay of radioactive ions, and -ray detectors. We describe here the setup, the commissioning experiment and some selected results demonstrating its performance for the measurement of half-lives and β-delayed neutron emission probabilities. Here, the methodology followed in the analysis of the data is described in detail. Particular emphasis is placed on the correction of the accidental neutron background.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1997

The source and distribution of Galactic positrons

The oriented scintillation spectrometer experiment (OSSE) observations of the Galactic plane and the Galactic center region were combined with observations acquired with other instruments in order to produce a map of the Galactic 511 keV annihilation radiation. Two mapping techniques were applied to the data: the maximum entropy method, and the basis pursuit inversion method. The resulting maps are qualitatively similar and show evidence for a central bulge and a weak galactic disk component. The weak disk is consistent with that expected from positrons produced by the decay of radioactive Al-26 in the interstellar medium. Both maps suggest an enhanced region of emission near l = -4 deg, b = 7 deg, with a flux of approximately 50 percent of that of the bulge. The existence of this emission appears significant, although the location is not well determined. The source of this enhanced emission is presently unknown.

Purcell, W. R.↗