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- Conference ObjectAçık Erişim2026Neutronic and thermal-hydraulic performance analysis of a novel thorium-based fuel in dual-cooled annular assemblies for SMR applications
Rifai, Hanan; Kabach, Ouadie; Uzun, Sinem; Genç, Yasin; Uzun, Bedrettin; Amsil, Hamid; Chakir, El Mahjoub; Sadoune, Zouhair; Didi, A.; Baatout, S.
A coupled neutronic and thermal-hydraulic assessment is performed for a dual-cooled annular fuel concept applied to light-water SMR conditions. A mixed thorium-based oxide, (Th-233U-235U)O2, is evaluated against conventional UO2 and solid-pin benchmarks while sweeping the inner moderator radius (0.05-0.43165 cm) at constant fuel volume. The thorium annular cases sustain an infinite multiplication factor (kinf) of 1.002-1.003 at EOC and achieve 3-batch discharge burnups of 166.3-173.5 GWd/t, compared with 142.4 GWd/t for solid UO2. Radial peaking remains low (maximum PPF ≈ 1.056, well below the 1.65 Westinghouse-types PWR design limit). All configurations exhibit negative FTC and MTC, with stronger negative feedback at larger inner radii. Thermal-hydraulic results show smooth coolant heating and robust DNBR margins (minimum ∼ 2.3) with negligible sensitivity to inner radius. These outcomes support the feasibility of thorium-based annular fuel for SMR deployment with improved fuel utilization and preserved safety margins.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2026Coupled Neutronic and Thermal-Hydraulic Analysis of Inner Moderator Radius Effects in Dual-Cooled Annular UO2 and Thorium-Based Fuels for a LW-SMR
Kabach, Ouadie; Rifai, Hanan; Uzun, Sinem; Genç, Yasin; Amsil, Hamid; El Banni, Fadi; Uzun, Bedrettin; Chakir, El Mahjoub
This study evaluated the effect of the inner moderator radius on the neutronic and thermal-hydraulic performance of dual-cooled annular UO2 and (Th-233U-235U)O2 fuels for a light water (LW) small modular reactor (SMR) derived from the AP300™ concept. The analysis combined lattice neutronic calculations and fuel channel thermal-hydraulic modeling to assess reactivity behavior, discharge burnup, cycle length, isotopic evolution, power peaking factor, pressure drop, coolant temperature rise, and departure from nucleate boiling ratio (DNBR). The results showed that the thorium-based fuel provided better fuel utilization than UO2 over the entire investigated range of inner moderator radii. Under single-batch operation, the discharge burnup of the thorium-based fuel reached 36.96 to 38.57 gigawatt-days per metric tonne (GWd/t), whereas the UO2 cases achieved 27.14 to 35.41 GWd/t. For a three-batch strategy, the thorium-based option attained 166.3 to 170.8 GWd/t and yielded longer operating cycles. It also significantly suppressed plutonium production and higher actinide accumulations, while reducing 135Xe and 149Sm poisoning. Increasing the inner moderator radius improved fertile-to-fissile conversion in both fuel systems; however, the thorium-based fuel exhibited much smaller performance degradation across the examined range. From the thermal-hydraulic standpoint, all the cases exhibited very similar behavior, with low power peaking factors, DNBRs near 2.3, and nearly unchanged pressure drop trends. Overall, the results demonstrated that thorium-based dual-cooled annular fuel is a promising option for improving fuel cycle performance while maintaining favorable thermal-hydraulic safety margins in LW SMRs.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2026A comprehensive assessment of neutronic and thermal–hydraulic behavior of some advanced accident-tolerant fuels in solid and dual-cooled annular PWR assemblies
Kabach, Ouadie; Uzun, Sinem; Genç, Yasin; Uzun, Bedrettin; Chakir, El Mahjoub; Amsil, Hamid
Accident-tolerant fuel (ATF) concepts are being evaluated to strengthen margins without sacrificing core economics. This study compares five ATF matrices, UN (with natural and enriched nitrogen), UC, UCO, U3Si2, and UAl2, implemented in 17 × 17 solid and 13 × 13 dual-cooled annular PWR lattices. Results show that the multiplication factor decreases monotonically with burnup in both geometries, which allows the use of the linear reactivity model to predict the reactor cycle length; UAl2 and UO2 provide the longest cycles. Assembly-level radial peaking remains low (≈1.05–1.09). All fuel and moderator temperature coefficients are negative, with the strongest feedback in annular UN (Natural N). Solid pins show a single outer-rim power/Pu-239 peak; annular pins split this into two milder rims and flatten the in-pin profile. Prompt (neutron-induced) power is essentially burnup-invariant by normalization, while decay heat grows with matrix density and conversion. Thermal-hydraulic results show that the annular geometry lowers coolant heating and pressure drop and raises the minimum DNBR by ∼ 55–65% relative to solid pins under identical boundary conditions.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2025Thermal-hydraulic investigation of novel thoriumuranium fuel mixtures in advanced SMR assembly configurations
Uzun, Sinem; Genç, Yasin; Rifai, Hanan; Kabach, Ouadie; Uzun, Bedrettin; Sadoune, Zouhair; Chakir, El Mahjoub; Amsil, Hamid; El Banni, Fadi
Nuclear energy sustainability and deployment flexibility can be significantly enhanced through Small Modular Reactors (SMRs) technology. Critical to their operational success is the thorough assessment of thermal-hydraulic characteristics, especially when incorporating advanced fuel design concepts. This research conducts an extensive thermal-hydraulic analysis examining various thorium-based fuel formulations, including (Th-235 U)O2, (Th-233 U) O2, and an innovative (Th-233 U-235 U)O2 composition, benchmarked against standard UO2 fuel. The investigation encompasses both solid fuel arrangements and dual-cooled annular assembly designs, focusing on safety optimization and operational efficiency enhancement. The analysis focuses on key safety parameters, including pressure drop, coolant enthalpy, fuel centerline temperature, and Departure from Nucleate Boiling Ratio (DNBR). Results for solid fuel configurations reveal that thorium-based fuels exhibit reduced pressure drop, more efficient enthalpy distribution, lower peak fuel temperatures, and higher DNBR values compared to conventional UO2, highlighting improved thermal stability and safety margins. The (Th-233 U-235 U)O2 mixture demonstrates a balanced performance by mitigating the limitations of other thorium compositions. In annular configurations, all fuel types benefit from enhanced heat removal due to the dual cooling surfaces, resulting in further reductions in pressure drop and peak temperatures, as well as a significant increase in DNBR values. The highest DNBR, reaching up to 3.051, confirms the annular geometry’s superior safety performance against boiling crises.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2025Innovative thorium-based fuel assemblies for LW-SMR: In-depth assembly-level neutronic analysis and safety considerations in solid and annular configurations
Rifai, Hanan; Kabach, Ouadie; Sadoune, Zouhair; Chakir, El Mahjoub; Uzun, Sinem; Amsil, Hamid; Banni, Fadi El
This study presents a comprehensive neutronic and safety evaluation of different thorium-based fuel compositions (Th-235U)O2, (Th-233U)O2, and a new proposed composition, namely, (Th-233U-235U)O2 fuel, compared to conventional UO2 in solid and dual-cooled annular assembly configurations in the context of Small Modular Reactors (SMR) applications. Results demonstrate that (Th-233U)O2 achieves the highest cycle length in both solid configurations, significantly exceeding UO2 performance. The proposed, however, (Th-233U-235U)O2 composition exhibits favorable safety characteristics, including enhanced negative temperature reactivity coefficients and favorable kinetic parameters. Annular fuel configurations also demonstrate superior thermal performance with centerline temperature reductions of approximately 50 °C compared to solid configurations and consistently lower power peaking factors throughout burnup. The findings indicate that thorium-based fuels, particularly (Th-233U-235U)O2 in dual-cooled annular configuration, offer compelling advantages for SMR applications, including extended fuel cycles, improved safety characteristics, enhanced proliferation resistance, and superior thermal performance, supporting their viability as sustainable alternatives to conventional uranium-based fuels.
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