Neutronic and thermal-hydraulic performance analysis of a novel thorium-based fuel in dual-cooled annular assemblies for SMR applications

¹ LESIPME, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco.
² LPMS, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco.
³ Faculty of Engineering and Architecture, Erzincan Binali Yıldırım University, Erzincan, Türkiye
⁴ Ministry of Interior, Disaster and Emergency Management Presidency, Ankara, Türkiye
⁵ Republic of Turkey Northeast Anatolia Development Agency, Erzincan, Türkiye
⁶ National Center for Energy, Sciences and Nuclear Technique, Rabat, Morocco

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 3 February 2026

Abstract

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 (k_inf) 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.