atw - International Journal for Nuclear Power | 2.2024

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70 Research and Innovation 2.2 Modeling TRISO particles in OpenMC Since, the Triso particles are randomly packed in the SiC matrix of the FCM fuel pallet. OpenMC can generate TRISO particles and distribute them randomly in the SiC matrix. The OpenMC. model. pack_spheres model has been used to distribute the Triso particles randomly within the fuel pallet. To model individual particles, a specific universe has been created, to model the individual particles, which not only reduces the simulation time but also improves the performance of performance by reducing the number of cells. 3. Results and Discussion In this study, FCM fuel based on UN and UCO TRISO particles fuel has been replaced for the SMART reactor without the design alteration of the SMART reactor and core. Therefore, the SMART reactor core has been modeled in OpenMC according to the design reported by the KAERI in [23] . The core burns up of the SMART reactor core have been evaluated without the control rods and Integral Fuel Burnable Absorber (IFBA) insertion. However, a boron concentration of 140 ppm has been considered according to the design as described in [23] . The burnup of UN and UCO-based FCM fuel has been simulated for identical operational and design constraints. In this study, the average axial thermal flux for FCM fuels of UN and UCO triso base particles has been simulated and compared with the reference design fuel (UO₂). The packing fractions of UN and UCO are 0.48 and 0.6 respectively. The comparison of the axial fluxes is shown in Figure 4. FCM fuel of UN and UCO has elevated thermal flux compared to the UO₂. The thermal flux is distributed over the dimension of the core 192.78 cm × 192.78 cm of mesh size of 4.8195 × 10 -1 . The candidate flux has elevated flux even with the presence of SiC and in the FCM fuel matrix. This is because of the higher enrichment and density of FCM fuel. One of the prime parameters to ensure the safety of the reactor operation is the reactor power density. Figure 5 depicts the comparison of normalized axial power. The normalized radial power distribution has been found to be almost identical at BOL, MOL, and EOL of fuel lengths. However, the elevated power has been seen at corner zone 2 (Figure 6) due to the higher enrichment of zone 2 assemblies. Whereas the flux at the central zone is less as compared to zone 2 because of the low enrichment of zone 1 (2.82 %wt of uranium). The FCM fuel loading follows the same configuration with 15.5 %wt of uranium in zone 2 assemblies and 9.5 %wt of uranium in zone 1 assemblies, which results in lower burnup at the central assemblies. However, the outer Fig. 4. Comparison of the thermal flux of the original fuel (UO 2 ) of the SMART reactor with the replaced FCM fuels (UCO and UN) Fig. 5. Axial normalized power distribution of SMART core at the BOL, MOL, and EOL of UO 2 and FCM fuels of UCO and UN kernels Ausgabe 2 › März
Research and Innovation 71 zoned assemblies have high burnup. The power density at the middle of the fuel length (MOL) and at the end of the fuel length (EOL) has a similar burnup pattern except for assembly type A at the edges of the outer zone, which have higher burnup due to higher enrichment compared to other assemblies that being depleted rapidly in addition to high neutron current scattered from the center of the core. 3.1 Powe peaking factor Local power density (LPD) is at the hottest point of a fuel rod and should be estimated accurately to confirm the possibility of a meltdown. The power peaking factor is defined as the highest LDP divided by the average power density in the reactor. The Power Peaking Factor (PPF) is the safety parameter that is essential for the localization of Departure from Nucleate Boiling (DNBR) and subcooled boiling. Figure 7 depicts the comparison of the PPF of FCM fuels with reference fuel. The FCM Fuel of UCO and UN has significantly low PPF compared to the standard design fuel of the SMART reactor. The maximums of PPFs for UO₂, UCO, and UN are 1.521,1.365, and 1.339, respectively. This indicates that the reactivity of FCM fuel is more controllable compared to the UO₂ fuel due to lower PPF values. Fig. 6. Comparison of normalized radial power distribution of UO 2 , UCO, and UN fuel for SMART reactor core at the beginning of fuel length (top), middle of fuel length (middle), and end of fuel length (bottom). 3.2 Effective multiplication factor and burnup The k effective criticality is fundamental and relevant for the safe and sustainable operation of reactors. Figure 8. There is a monotonic behavior of reactivity that has been exhibited by FCM fuel at the end of fuel length, where the effective multiplication monotonically decreases due to the high burn up rate. Initially, the keff of the FCM fuel is higher than the conventional Fig. 7. Comparison of the PPF of FCM fuel of UN and UCO and reference core. Fig. 8. k effective for one complete fuel length with a boron concentration of 140 ppm. Fig. 9. Comparison of the burnup rate of FCM and Reference fuel for one fuel length with the boron concentration of 140 ppm. Vol. 69 (2024)
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ISSN: 1431-5254 (Print) | eISSN: 29
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4 Contents Inhalt Editorial Abschie
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6 Calendar Kalender 2024 07.03.2024
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8 Feature: Energy Policy, Economy
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18 Energy Policy, Economy and Law
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Page 36 and 37: 36 Operation and New Build VR Topi
Page 38 and 39: 38 Operation and New Build Fig. 8.
Page 40 and 41: 40 Operation and New Build [47] Bo
Page 42 and 43: 42 Operation and New Build [127] H
Page 44 and 45: 44 Environment and Safety Initial
Page 46 and 47: 46 Environment and Safety S/N Docu
Page 48 and 49: 48 Environment and Safety compared
Page 50 and 51: 50 Environment and Safety EPZ EPD
Page 52 and 53: 52 Environment and Safety Emergenc
Page 54 and 55: 54 Environment and Safety In 2015,
Page 56 and 57: 56 Environment and Safety populati
Page 58 and 59: 58 Environment and Safety [38] A.
Page 60 and 61: 60 Environment and Safety Evaluati
Page 62 and 63: 62 Environment and Safety Material
Page 64 and 65: 64 Environment and Safety EFPY (Ef
Page 66 and 67: 66 Environment and Safety Referenc
Page 68 and 69: 68 Research and Innovation replace
Page 72 and 73: 72 Research and Innovation fuel (U
Page 74 and 75: 74 Research and Innovation [12] Po
Page 76 and 77: 76 Spotlight on Nuclear Law auf Ko
Page 78 and 79: 78 KTG-Fachinfo KTG-Fachinfo 02/202
Page 80 and 81: 80 KTG-Fachinfo Regierungsbericht v
Page 82 and 83: 82 Vor 66 Jahren Ausgabe 2 › Mä
Page 88 and 89: 88 Kerntechnik 2024 Technical Sess
Page 90 and 91: 90 Kerntechnik 2024 Technical Sess
Page 92 and 93: 92 Kerntechnik 2024 Partner, Ausst
Page 94 and 95: 94 KTG Inside Die KTG gratuliert a
Page 96 and 97: 96 KTG Inside † Nachruf Die Kern
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atw - International Journal for Nuclear Power | 2.2024

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