This paper uses a combined single-assembly and full-core benchmark problem based on a heat-pipe-cooled microreactor design to study the effect of core environment on homogenized multigroup macroscopic cross sections g...
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This paper presents preliminary full-core neutronics analysis for nuclear Thermal Propulsion (NTP) reactors using nodal diffusion codes. NTP reactor physics analyses generally rely on high-fidelity simulations (e.g., ...
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nuclear thermal propulsion is an evolving technology that can be utilized for long-distance space travel. This technology yields the advantage of high thrust efficiencies that provides an edge over the accustomed chem...
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Radiation effect in carbon fiber-filled polyethylene composites are of importance in space and aircraft applications. A two-fold approach is employed to study radiation effects in carbon nanotube polyethylene as the e...
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This study conducts a comparison of atmospheric dispersion models for use in future advanced reactor licensing and Emergency Planning Zone (EPZ) siting. The comparison utilized the existing SOARCA Peach Bottom boiling...
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In response to radiological or nuclear emergencies, prompt assessment of internal radiation contamination is critical for triage assessment and medical countermeasures administrations. The NAIS-2’2 NaI(Tl) scintillat...
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ISBN:
(数字)9798350388152
ISBN:
(纸本)9798350388169
In response to radiological or nuclear emergencies, prompt assessment of internal radiation contamination is critical for triage assessment and medical countermeasures administrations. The NAIS-2’2 NaI(Tl) scintillation detectors were selected to construct a scanning system to measure internalized gamma-ray emitting radionuclide contamination in warfighters. A mesh-type adult female anthropomorphic phantom of 165 cm height and 65 kg weight was used, and an eight-point detector grid was implemented covering critical body areas (head, neck, chest, abdomen, and hip) implemented in the Monte-Carlo simulation tool, PHITS. The gamma depositions from critical radionuclides were simulated across all organs of interests. Biokinetic modeling data of each radionuclide were incorporated to determine the time-dependent retention in these organs and the gamma depositions in the detectors. To optimize the number and position of detectors for contamination characterization, a scoring algorithm was developed by analyzing the pseudo planes across the anterior and posterior of the phantom. These planes were subdivided into fine meshes to simulate the gamma flux, which were then integrated with biokinetics to compute the detector counting efficiencies at various times post-inhalation. This integration will enable the identification of the optimal detector array configuration, achieving the best counting statistics for various combinations of radionuclide sources, times post-exposure, and phantom morphologies, and the reconstruction of total contamination patterns.
Conventional silicon radiation detectors suffer from severe carrier recombination in the heavily doped p + and n + layers or regions, as well as beneath the metal contact areas, especially on the detector side, whic...
Conventional silicon radiation detectors suffer from severe carrier recombination in the heavily doped p + and n + layers or regions, as well as beneath the metal contact areas, especially on the detector side, which is also known as "dead layer". Here we present the tunnel oxide passivating contact with an outstanding carrier selectivity. Its key element is an ultra-thin (~1.5 nm) interfacial oxide layer that can allow an efficient transportation of majority carriers via tunneling, while effectively block the minority carriers. The extraordinarily low saturation current density of 5 ~ 10 fA/cm 2 even with the metal contact (electrode), which was measured by the quasi-steady-state photoconductance, proves the superiority of tunnel oxide passivating contact. While conventional p-n junction or high-low junction have the saturation current density in the range of 10 ~ 90 fA/cm 2 for the passivated p + and n + layers due to Auger recombination, and 800 ~ 6000 fA/cm 2 for the metal contact areas because of significant metal-induced recombination at the interface. This demonstrates the potential and supremacy of applying the tunnel oxide passivating contact for silicon radiation detectors to thoroughly collect the generated charge carriers, leading to much higher energy resolution.
The methodology and results summarized in this paper demonstrate that the ntpThermo code is a suitable reduced-order code for engineering and full-core multiphysicsanalysis of NTP reactors. Additionally, the analysis ...
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