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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Novel methods for TH-229 production through fast neutron irradiation of TH-23F0 and charged particle irradiation of Th-230 and Th-232. Final Report DE-SC0020140

The activities and results of research related to accelerator production of Pa and Th isotopes via bombardment of 230 Th and 232 Th targets are described herein. This research was supported through DOE grant DE-SC0020140 and was conducted in collaboration with Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory. Cross section measurements, transport model and nuclear physics model calculations are presented. Highlights include the first ever measurements of 229 Pa, two publications, and graduation of a PhD student.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Fast Neutron Irradiation Embrittlement-ductilitization of an Iron-based Amorphous Alloy using In Situ Synchrotron X-ray Diffraction

Amorphous Fe-based nanostructured alloy coatings thermally sprayed on bcc steel substrate, were subjected to neutron irradiation doses up to 2 × 10 19 n/cm 2 . It is shown that the interplay between embrittlement and recovery of ductility is governed by amorphous to crystallization transition and phase decomposition in which temperature and irradiation dose have reciprocal effects. Microscopic (X-ray diffraction) observations on the behavior of the amorphous Fe-based alloy are correlated with relevant macroscopically observed mechanical behavior. It is shown that amorphous Fe-based alloy coatings maintain and even enhance their amorphous structure with irradiation, exhibit radiation-induced restoration of thermally-induced embrittlement and finally exhibit resistance to ductility loss up to the fluence of 2 × 10 18 n/cm 2 and good thermal stability up to 350 °C. The latter is deduced from X-ray diffraction experiments of in-situ tensile strain application on the irradiated coating.

36 MATERIALS SCIENCE↗
NASA NTRS1972

Relative biological effectiveness of fast neutrons compared with X-rays: Prenatal mortality in the mouse

The effects of fission neutrons and of X-rays on the mouse zygote are discussed. Seven-week-old virgin mice were allowed a 12-hour mating opportunity beginning at 7:00 P.M. Between 1:30 and 4:00 P.M., except where indicated otherwise, the females which had mated (vaginal plug) during the night were either irradiated or sham-irradiated. At the time of irradiation the zygotes were in a pronuclear stage. Sixteen days later the mice were killed and the uteri dissected. The number of dead embryos, live embryos, and gross anomalies were determined. Dead embryos were classified as to stage of development.

Friedberg, W.↗
NASA NTRS1973

Fast-neutron spectrometer developments

Li6 sandwich-type neutron spectrometer is equipped with proportional counter for particle identification. System uses current-sensitive preamplifiers to minimize pile-up of gamma-ray and particle pulses.

Moler, R. B.↗
NASA NTRS1973

Measured and calculated fast neutron spectra in a depleted uranium and lithium hydride shielded reactor

Measurements of MeV neutron were made at the surface of a lithium hydride and depleted uranium shielded reactor. Four shield configurations were considered: these were assembled progressively with cylindrical shells of 5-centimeter-thick depleted uranium, 13-centimeter-thick lithium hydride, 5-centimeter-thick depleted uranium, 13-centimeter-thick lithium hydride, 5-centimeter-thick depleted uranium, and 3-centimeter-thick depleted uranium. Measurements were made with a NE-218 scintillation spectrometer; proton pulse height distributions were differentiated to obtain neutron spectra. Calculations were made using the two-dimensional discrete ordinates code DOT and ENDF/B (version 3) cross sections. Good agreement between measured and calculated spectral shape was observed. Absolute measured and calculated fluxes were within 50 percent of one another; observed discrepancies in absolute flux may be due to cross section errors.

Lahti, G. P.↗
NASA NTRS1980

Preliminary results of fast neutron treatments in carcinoma of the pancreas

A group of 30 patients with adenocarcinoma of the pancreas including some patients with very advanced disease, were treated with the so-called mixed beam modality employing photon treatments three times per week and neutron treatments twice a week. Two hundred Rads or equivalent Rads (RBE 3.3) were given in daily fractions aiming at a total dose of 6000 Rads in 6 to 8 weeks. The treatments were well tolerated and significant palliation was achieved in 26 to 30 cases. Twelve months survival was 33 percent with a median survival of 7 months or 210 days. Treatment techniques and localization procedures are discussed.

Gahbauer, R.↗
NASA NTRS2020

Fast Neutron Spectroscopy with Organic Scintillation Detectors in a High-Radiation Environment

Organic scintillators with pulse shape discrimination capability are widely used in both research and practical applications of neutron detection. The neutron and gamma-ray identification performance of the detector depends on the classification algorithms, noise filters and pileup rejection criteria in a high-flux bremsstrahlung radiation environment. In this paper, a technique has been developed and implemented for the neutron detection with multiple filter and discrimination steps, which to a high confidence level eliminates counting of gamma-ray pulses. Such a technique is merited when making measurements in a high flux bremsstrahlung and secondary fluorescence environment. The EJ-309 and stilbene detectors coupled to the digital data acquisition system were used for the calibration assessments with standard gamma-ray and neutron sources such as 137Cs, 60Co, 252Cf, and Am-Be. The MCNPX-PoliMi and GEANT4 toolkits were used to simulate the light output and the optical photon transport in the scintillators and create detector response functions for each type of detector. The neutron spectrum unfolding algorithm, GRAVELW, was used to recreate and calibrate with the Am-Be as final step before applying the neutron detection system to extract fusion neutron spectra generated in an intense bremsstrahlung radiation environment. This new technique described offers the user the ability to measure neutron spectra in a high-flux gamma-ray field and tune the parameters to meet required filtering needs.

Neutron Detector, Organic Scintillator, PulseShape↗