This paper describes the experimental results for an energy tuning assembly created to modify the National Ignition Facility deuterium–tritium fusion neutron source into a notional thermonuclear and ...prompt fission neutron spectrum, which has applications in integral measurements, nuclear data benchmarks, and radiation effects on microelectronics. The Monte Carlo neutron transport utilized MCNP5 to estimate the ETA-modified fluence using the ENDF-B/VIII.0 and IRDFF-II continuous energy nuclear data libraries, and SCALE Sampler was used to estimate the systematic nuclear data covariance using ENDF-B/VII.1 and IRDFF-II in a 252-group structure. The experiment fielded eight activation foils and a highly enriched uranium sample. This provided fifteen reaction channels that were used in a forward-fit comparison to the modeled results and to unfold the neutron spectrum using STAYSL. Gamma-ray spectrometry was performed on the activation and highly enriched uranium foils, and the reduced χ2 between the modeled and experimental values was 1.21. The results from the STAYSL unfold, reduced χ2=1.62, indicated that the modeled neutron spectrum was achieved and the systematic nuclear data uncertainty associated with the neutron transport and activation product cross sections was representative of the experiment. Integral cumulative fission product yield data were collected for 37 mass chains with a combination of gamma-ray spectrometry and radiochemical analysis. Fission product analysis was generally in agreement with two models using a semi-empirical fit and the General Observables of Fission code, with the exception of mass chains 88, 109, 111, 112, 113, 129, 139, 142, 144, 151, and 156.
•Energy tuning assembly to create thermonuclear and prompt fission neutron spectrum.•MCNP and SCALE Sampler simulations characterized neutron fluence and covariance.•Neutron fluence unfolded with PNNL STAYSL using activation foils and IRDFF library.•Highly enriched uranium fission products were quantified over 37 mass chains.
The synthesis, IR spectroscopy, thermal and UV-Vis transmittance of the new lithium iodate crystal: (H3O)Li2(IO3)3, were studied. The crystal structure of (H3O)+·2(Li)+· 3(IO3)- was determined by ...single-crystal X-Ray diffraction analysis at 100(2) K. It crystallizes in the monoclinic system (P21/n) with the parameters: a = 8.3266(12) Å, b = 10.9893(17) Å, c = 11.2472(17) Å, α = γ = 90°, β = 111.360(4)° and Z(Z') = 4(1). The structure contains a hydronium cation (H3O)+, three crystallographic independent trigonal pyramidal IO3 anions, and two independent cations (Li)+ coordinated each by four oxygen atoms 3(IO3)- at the apices of strongly deformed tetrahedrons. The research results have revealed the mechanisms of crystal formation and the characteristic absorption bands of functional groups, which are of scientific importance. The possibility of the existence of certain properties is also discussed.
The generation of dynamic high energy density plasmas in the pico- to nano-second time domain at high-energy laser facilities affords unprecedented nuclear science research possibilities. At the ...National Ignition Facility (NIF), the primary goal of inertial confinement fusion research has led to the synergistic development of a unique high brightness neutron source, sophisticated nuclear diagnostic instrumentation, and versatile experimental platforms. These novel experimental capabilities provide a new path to investigate nuclear processes and structural effects in the time, mass and energy density domains relevant to astrophysical phenomena in a unique terrestrial environment. Some immediate applications include neutron capture cross-section evaluation, fission fragment production, and ion energy loss measurement in electron-degenerate plasmas. More generally, the NIF conditions provide a singular environment to investigate the interplay of atomic and nuclear processes such as plasma screening effects upon thermonuclear reactivity. Achieving enhanced understanding of many of these effects will also significantly advance fusion energy research and challenge existing theoretical models.
The impact of various ion chromatography parameters on the separation of trace amounts of thulium from erbium was examined to address the need for the preparation of a
171
Tm target for neutron ...capture cross section measurements. The following optimal operation parameters for analytical scale separations with cation exchange resin were established based on a modified separation resolution: 0.046 M α-HIB
−
as eluent with a flow rate of 1.2 mL min
−1
at 25 °C. Different carboxylic acids with varying pH were also investigated, which reaffirmed the use of α-hydroxyisobutyrate as the most suitable complexant for the separation of these neighboring lanthanides.
Gamma spectrometry in the ITWG CMX-4 exercise Lakosi, L.; Zsigrai, J.; Kocsonya, A. ...
Journal of radioanalytical and nuclear chemistry,
2018, Letnik:
315, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Low enriched uranium samples of unknown origin were analyzed by 16 laboratories in the context of a Collaborative Materials Exercise (CMX), organized by the Nuclear Forensics International Technical ...Working Group (ITWG). The purpose was to compare and prioritize nuclear forensic methods and techniques, and to evaluate attribution capabilities among participants. This paper gives a snapshot of the gamma spectrometric capabilities of the participating laboratories and summarizes the results achieved by gamma spectrometry.
Nuclear fusion experiments performed at the National Ignition Facility produce radioactive debris, arising in reactions of fast neutrons with the target assembly. We have found that postshot debris ...collections are fractionated, such that isotope ratios in an individual debris sample may not be representative of the radionuclide inventory produced by the experiment. We discuss the potential sources of this fractionation and apply isotope-correlation techniques to calculate unfractionated isotope ratios that are used in measurements of nuclear reaction cross sections.
•Debris from fusion experiments at the National Ignition Facility is inhomogeneous.•Fractionation techniques allow calculation of the average radionuclide inventory.•Corrected radionuclide concentrations support the calculation of nuclear cross sections.
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