Yazar "Lule, Senem Senturk" seçeneğine göre listele

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    A methodology to solve computational power issue for high fidelity loose and explicit Monte Carlo-CFD coupled multi-physics analysis for block type HTGRs
    (Pergamon-Elsevier Science Ltd, 2026) Lule, Senem Senturk; Sayin, Sefa; Kutbay, Feride; Bircan, Muhammed Mustafa; Colak, Uner
    High Temperature Gas Cooled Reactors (HTGRs) offer wide range of applications besides electricity generation therefore different designs are under development with multi-physics modeling. Although neutronic calculations of block type HTGRs are quite straight forward, thermal-hydraulic calculations are challenging due to complex heat transfer mechanism in the core. In addition, if high fidelity is applied, the computational power and time requirement is quite high. The high fidelity, loose, and explicit coupling multi-physics approach with Monte Carlo and computational fluid dynamics codes was proposed in this study that minimizes the computational power need without losing accuracy. The proposed methodology was tested with Holos Quad Core microreactor. The calculations showed that both neutronic and thermal-hydraulic simulation results of the proposed methodology are within 4% difference level with the results given for Holos microreactor therefore showing the proposed methodology's reliability.
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    Öğe
    Assessment of the detection efficiency calibration of high-resolution gamma-ray spectrometers by EGSnrc and MCNP6.2 Monte Carlo codes
    (Pergamon-Elsevier Science Ltd, 2023) Sayin, Sefa; Seferinoglu, Meryem; Yeltepe, Emin; Cetin, Berkay; Lule, Senem Senturk
    Determination of the activity content of radionuclides with high accuracy and precision with gamma-ray spectrometry is strongly based on the detection efficiency calibration of the detector. The detector efficiency calibration is determined with standard reference sources and/or Monte Carlo codes. The current study provides methodology that can be used to generate efficiency curve with simulations instead of experiments. As a result, the need for additional experiments can be reduced. The implementation of a specific script written on EGSnrc Monte Carlo code was investigated to calculate the detection efficiency with high-level accuracy for high-purity germanium (HPGe) spectrometry. For this purpose, two HPGe detectors (ORTEC and PGT) used routinely in the activity measurement of gamma emitting radionuclides were modelled with EGSnrc code to obtain detection efficiencies for 40-2000 keV energy range. The detector models were benchmarked against MCNP6.2 Monte Carlo code with a hypothetical source geometry. The code-to-code comparison between EGSnrc and MCNP6.2 codes indicted that the codes can be used to generate a reliable detection efficiency curve. The benchmark results showed that median arithmetic deviations of the efficiencies of ORTEC and PGT detectors are found as 0.88% and 1.69%, respectively. The experimental studies were performed with 22Na, 57Co, 60Co, 137Cs, and 241Am standard disc sources for the ORTEC detector and with in-house prepared 152Eu sandwich-type source for the PGT detector. The sources were counted in the energy range of 59.5-1408 keV. The efficiency values from simulations were used in the calculation of the activities of the aforementioned gamma sources with a mathematical formula and resulting measured activity values were compared with reference activity values given in the certificates. In addition, the applicability of spreadsheet approach that is usually used to determine the combined standard uncertainty for alpha-particle spectrometry was investigated for gamma-ray spectrometry. The performance of the recommended procedure was scored in terms of relative bias, z-score, u-test, trueness, and precision. The activity results obtained with simulated efficiencies showed good agreement with certified values.
  • [ X ]
    Öğe
    New thorium core loading patterns for high temperature gas cooled nuclear microreactors
    (Pergamon-Elsevier Science Ltd, 2025) Lule, Senem Senturk; Bircan, Muhammed Mustafa; Kutbay, Feride; Sayin, Sefa; Colak, Uner
    Ten different 50:50 vol ratio thorium core loading configurations for a chosen HTGR microreactor were compared with original uranium core loading from neutronics point of view. 2.72 x 109 individual TRISO particles except for homogeneous fuel configuration were modeled. The best configuration was achieved when fuel channels with three layer axial ThCO-UCO-ThCO seed/blanket were placed in the core as radial seed/blanket configuration with ThCO filled fuel channels. With thorium loading, initial criticality was reduced from 1.301 to 1.2619 and EFPD from 3500 days to 1775 days but power generation, power peaking factor, and maximum axial power peaking factor in the highest power producing fuel channel were increased therefore the burnable poison distribution optimization was performed to reduce these parameters. When compared with 20.35 kW, 2.13, and 1.3 values for aforementioned parameters for uranium configuration, 20.70 kW, 2.17 and 1.70 values for thorium core loading are acceptable.