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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Characterization of D-T Generator Neutron Flux Spectrum for Cyclic Neutron Activation Analysis Experiments

Improving nuclear data for short-lived fission product yields will further our fundamental understanding of fission, which is needed across various scientific fields and applications. One method of attaining the needed product yield data is through cyclic neutron activation, which allows a target to be irradiated in a neutron environment and then transported for counting of the radionuclides produced, typically via g spectroscopy. Recently, such a system has been constructed and commissioned at Pacific Northwest National Laboratory. Targets are shuttled between the head of a D-T neutron generator and a counting station with a transit time of 2 seconds. As part of the characterization of this system, the neutron flux was studied using two activation targets. The neutron flux from the deuterium-tritium fusion generator was determined to be 9.95(33) x10^8 n/cm2-s with a peak energy of 14.9 MeV and a spread of approximately 4 decades between the epithermal and 14 MeV peak group flux.

cyclic neutron activation, gamma-ray spectroscopy,↗
DOE OSTI2023

Performance Evaluation of the Starfire nGen-350 DD Neutron Generator for use with the Fast Neutron Coincidence Collar

The Starfire Industries nGen-350 DD neutron generator has been developed for use with the Fast Neutron Coincidence Collar (FNCL). The generator was adapted from the nGen-310 model generator by Starfire to accommodate an International Atomic Energy Agency (IAEA) request to incorporate a neutron yield stabilization mechanism. An nGen-350 generator was obtained by Oak Ridge National Laboratory (ORNL) for evaluation as a potential neutron interrogation source replacement for Am(Li) in the FNCL. This report provides a summary of the performance of the nGen-350.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Pulsed-Neutron Die-Away Response of H 2 O Targets to a D-T Neutron Generator Pulse

Pulsed-neutron die-away (PNDA) experiments were completed at Lawrence Livermore National Laboratory (LLNL). The goal of these experiments was to provide a benchmark to validate thermal neutron scattering laws of H 2 O. The experiment was conducted with a deuterium-tritium (D-T) neutron generator producing pulses of 14.1 MeV neutrons that impinged on a moderating target.

3He Detectors↗
DOE OSTI2025

Neutron Yield of Thermo Scientific P385 D-T Neutron Generator vs . Current and Voltage

The Thermo Scientific P385 Neutron Generator is a compact neutron source, producing 14 MeV neutrons through the deuterium-tritium (DT) fusion reaction. It is important to measure and understand the dependence of the neutron production rate on the accelerator current and voltage. In this study we evaluated neutron production with an absolutely calibrated liquid scintillator neutron spectrometer (BTI N-Probe), an absolutely calibrated He-3 detector surrounded by HDPE shells (Detec Nested Neutron Spectrometer, NNS), and two uncalibrated ZnS fast neutron scintillators (EJ-410), for both A3082 and A3083 sealed tubes. Here we also modeled the neutron yield using the TRIM code, which calculates the trajectory and the energy loss of deuterons and tritons within the target. Experimental results showed an essentially linear dependence on beam current, as expected. A 3.59 ±0.08 power law dependence on the operating voltage was measured, in effective agreement with the modeled value of 3.5. A series of absolute NNS and N-Probe measurements, matched against MCNP calculations, showed that the A3083 and A3082 tubes provide a maximum neutron yield of 8.2 × 10 8 n/s and 4.7 × 10 8 n/s respectively, with estimated uncertainty of ±10%.We showed, through modeling, that tritium decay is not a significant consideration for tubes, such as these, with lifetimes of less than 10 years.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Grating-Based Imaging-Scattering with Portable Neutron Generator

Company: Adelphi Technology, Inc. Title: Grating-Based Imaging-Scattering with Portable Neutron Generator PI: Dr. Jay Theodore Cremer, Jr. Topic: 26a Statement of the problem or situation that is being addressed. Successful plant growth depends upon an efficient and robust root system. The plant root is part of a larger system of water and microbial flows in the soil system. While much effort has been exerted to develop an imaging system for water, microbes, and roots, the problem is challenging, and no widely accepted imaging method currently exists. The optical solutions use a highly modified soil system. X-ray imaging methods are insensitive to the soft tissues in the presence of sand. Thermal neutron imaging has been often tested, but found inadequate, due to limited access and low image resolution. This project will develop a new strategy for neutron imaging of plant/soil systems. The project will allow long duration experiments in greenhouse environments and increase the image information content to the micron scale. General statement of how this problem is being addressed. Portable, rugged thermal and fast neutron sources are being developed where portable means a two-soldier team can carry the source and power unit to survey rough terrain for explosives. In the past decade, microfabrication of X-ray and thermal/cold neutron optics has opened a new imaging strategy. The standard transmission image is now supplemented with simultaneous acquisition of a phase contrast image and an image revealing scattering features. In materials science, the interferometric neutron scattering image has been used to detect early crack formation in stressed additive manufacturing test samples. The detection requires sensitivity to scattering features at the 1-micron scale. By addition of our proposed grating-optic to Adelphi Technology’s radiographic/tomographic imaging system, which is based on portable thermal neutron source, the resulting thermal neutron scatter image of the plant/soil system, will reveal details at 1-micron. Commercial Applications and Other Benefits Neutron interferometry imaging has greater penetration through large metal components compared to industrial X-ray imaging. The low-cost, large area optics developed for greenhouse applications, combined with the robust, portable neutron generator, can then be marketed as a system for inspection of additive manufactured components. In the aerospace industry, all freshly printed components are validated with X-ray CT. Scheduled maintenance again requires X-ray CT as the ability to predict aerospace component lifetime does not yet exist. Large aerospace components are only partially observed with X-ray imaging. Key Words Neutron radiography/tomography, grating interferometry, thermal neutron generator imaging, plant root and soil imaging, rhizosphere imaging, deployable neutron imaging systems Summary for Members of Congress A rugged, portable source of thermal neutrons is adapted for neutron interferometry imaging with the addition of low-cost, 3D printed optics. The first application of our proposed deployable, compact thermal neutron generator imaging system, using a grating optic, is plant root/soil science in greenhouse settings and agricultural laboratories.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Fusion Neutron Generator

The proposed code, named FROG (Fusion neutron Generator) is built upon the open-source particle transport Monte Carlo toolkit Geant4. Geant4 provides C++ classes that can be leveraged to build application-specific codes dealing with the transport of particles through matter. Geant4-based codes are applied in high-energy particle physics experiments, medical applications, shielding, and space applications for example. The FROG code allows the user to define the geometry of a neutron converter device shaped as a hollow cylinder, where a neutron breeding material such as lithium deuteride (LiD) is cladded by two concentric cylinders. Such neutron converter is then placed inside a regular nuclear fission reactor, where thermal neutrons will react with the neutron breeder material (typically, Lithium 6), and through a series of reactions, will generate high-energy neutrons – neutrons whose kinetic energy are around 14 MeV. The hollowed central portion can hold a specimen that will be bombarded by high-energy neutrons created inside the neutron breeding material. Figuratively speaking, this type of device transforms neutrons from thermal (~0.625 eV) to fusion (~14 MeV) energies and is sometimes termed “fusion-to-thermal neutron converters” in the literature. The code consists of C++ source file compiled and linked to generate an executable. The user can select the dimensions of the converter (radius, length, and thickness of the breeder material), the breeder material type, the cladding material, and the specimen material that will be activated or irradiated. As input, the neutron flux for a specific location inside a reactor, for instance, positions in ATR, is required. As output, the code predicts the number of high-energy neutrons produced, the total neutron flux and fluence as well as its detailed spectrum. The physics involved in such device is very complex, as it requires modeling neutron transport, light-ion (tritons) transport, as well as fusion reactions. The Geant4 toolkit provides the required physical models.

Martin, NicholasP. [Idaho National Laboratory (INL↗
DOE OSTI2024

Use of a deuterium-deuterium neutron generator for the Add-A-Source waste matrix correction technique

Neutron generators offer an alternative to radioactive sources in the application of active techniques for nondestructive assay of nuclear materials. The Add-A-Source technique has enabled improvements in the ability to accurately measure waste bearing nuclear materials by measuring and correcting for the non-nuclear matrix effect. The technique has historically been performed with a Cf-252 spontaneous fission source. Here, in this work, we have demonstrated the use of a Deuterium-deuterium neutron generator in place of the Cf-252 source. A DD generator enables operational advantages and allows the simplification of the instrument design, while offering equivalent corrective performance as a Cf-252 source.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Operation of the Fast Neutron Coincidence Collar (FNCL) with a DD-Neutron Generator

For more than 30 years, the quantitative assay of the 235 U content of light water reactor fresh fuel assemblies relied on measuring coincidence neutrons from fissions induced by an Am(Li) neutron source using 3 He based detectors. The Fast Neutron Collar (FNCL) developed by the International Atomic Energy Agency (IAEA), replaces traditional 3 He proportional counters with an array of liquid scintillator detectors arranged about the fuel assembly to provide improved measurement precision and reduced sensitivity to gadolinium poison rods. The FNCL relies on Am(Li) neutron sources that are no longer commercially available. This work examines the replacement of Am(Li) sources with a commercial off the-shelf deuterium–deuterium (DD) neutron generator. In addition to mitigating supply concerns, the neutron generator offers advantages in measurement precision and potential automation of sequential passive/active neutron measurements. This report presents the initial performance results for both the integrated DD/FNCL and Am(Li)/FNCL assays of compact depleted uranium, low-enriched uranium, and highly enriched uranium standards along with an estimate of the expected performance for fresh fuel assemblies. A discussion of the design and operation of the “FNCL Analysis and Simulation Software” is also provided.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Pump Development for Fusion-Based Neutron Generators

Tritium usage in fusion-based neutron generators is low for each pulse. This requires the deuterium/tritium mixture to be evacuated and recycled during downtime or to remove the helium buildup. Because of the pressure ranges and to minimize space, turbomolecular pumps are being considered for the tritium recirculation pumps. Two main types were initially considered: Agilent TwisTorr and Osaka TG-MR.

Angelette, Lucas M. [Savannah River National Labor↗
DOE OSTI2025

Neutron generation dynamics inside a MA-class dense plasma focus Z-pinch

Dense plasma focii (DPFs) are appealing as energy efficient sources of short pulses of ions, neutrons, and x rays. The output of these sources is expected to scale with input current (I4), but has been shown to drop at the MA level [S. K. H. Auluck, “On the failure of neutron yield scaling in the dense plasma focus,” Phys. Plasmas 30, 080701 (2023)]. New results on the MegaJOuLe Neutron Imaging Radiography DPF showed neutron yield production in agreement with the input current scaling beyond the previously observed drop. This work provides insight into the pinch formation on a DPF and reports on the two different mechanisms leading to neutron generation inside a DPF using a combination of kinetic simulations and experimental data. A combination of particle-in-cell (PIC) and 1D shock theory results are used to describe the pinch formation and disassembly and the corresponding thermonuclear and beam-target mechanisms. The temporal evolution of the pinch column predicted by the PIC simulations shows qualitative agreement with the experimental data from plasma photon emission as well as temporal neutron pulse shapes. In MJ-class DPFs, both thermonuclear and beam-target mechanisms can occur over the course of the implosion and contribute to the total neutron production. Hence the neutron source size of a DPF will change throughout the implosion. Experimental neutron radiographs show the increase in source size as the pinch breaks apart, in agreement with simulation's prediction.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Neutron generation using pyroelectric crystals

A method for producing a neutrons includes producing a voltage of negative polarity of at least −100 keV on a surface of a deuterated or tritiated target in response to a temperature change of a pyroelectric crystal of less than about 40° C., the pyroelectric crystal having the deuterated or tritiated target coupled thereto, pulsing a deuterium ion source to produce a deuterium ion beam, accelerating the deuterium ion beam to the deuterated or tritiated target, and directing the ion beam onto the deuterated or tritiated target to make neutrons using at least one element of the following: a voltage of the pyroelectric crystal and a high gradient insulator (HGI) surrounding the pyroelectric crystal. The accelerating of the deuterium ion beam is achieved by using an ion accelerating mechanism comprising a pyroelectric stack accelerator having a first thermal altering mechanism for changing a temperature of the pyroelectric stack accelerator.

Tang, Vincent↗
DOE OSTI2024

Quasi-monoenergetic ion acceleration and neutron generation from laser-driven transverse collisionless shocks

Experiments using the OMEGA EP laser system were performed to study collisionless shock acceleration of ions driven by the interaction of a relativistically intense laser pulse with underdense plasma. The energy spectrum of accelerated ions in the direction transverse to laser propagation is measured to have several narrow-band peaks which are quasi-monoenergetic with a typical energy bandwidth of 3%. In deuterium plasmas, these ions generate a significant number of fast fusion neutrons. Particle-in-cell simulations confirm that these ions were accelerated by the interaction of transverse shocks and that the appearance of quasi-monoenergetic spectral features depends on the growth of an ion-electron two-stream instability during the interaction.

Kordell, P. (ORCID:0000000321456317)↗
DOE OSTI2025

Neutron diagnostics and neutron generation with Z-Petawatt

We are developing a versatile neutron test platform at the “Chama” target chamber at Sandia to utilize Z-Petawatt in support of Z’s neutron diagnostic work. Details and first results are given in the poster.

Geissel, Matthias [Sandia National Laboratories (S↗
NASA NTRS1974

Long life neutron generator target using deuterium pass-through structure

Target structure permits all deuterons, except the one-in-a-million that interacts with tritium atom to produce a neutron, to pass completely through target structure and be returned to vacuum system. Since tritium atoms are not displaced as in conventional targets, tritium population will remain unchanged while under deuteron bombardment.

Alger, D. L.↗