https://doi.org/10.1051/epjn/2025077
Regular Article
Safety-related investigations designing a soluble-boron-free small modular reactor core at equilibrium
Karlsruhe Institute of Technology (KIT), Hermann-vom-Helmholtz-Platz-1, Eggenstein-Leopoldshafen 76344, Germany
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Received:
16
June
2025
Received in final form:
6
October
2025
Accepted:
19
November
2025
Published online: 6 February 2026
Abstract
Many water-cooled SMRs (WC-SMRs) are being developed and their deployment is being considered in different countries world-wide, with some designs considering no soluble boron in the coolant. The elimination of soluble boron in the coolant of WC-SMRs offers advantages such as an enhanced negative moderator temperature coefficient, reduced corrosion, and simplified chemical systems, etc. leading to the growing interest in Soluble-Boron-Free (SBF) SMR-designs. Without soluble boron, excess reactivity control relies on burnable absorbers and control rods, potentially increasing power peaking factors and requiring careful core design to ensure safety margins. This study starts with an academic SBF Karlsruhe Small Modular Reactor (KSMR) core designed with a fresh fuel loading in order to find an optimal equilibrium cycle following a two-batch refueling strategy by optimizing fuel enrichment, burnable absorber rod configuration, and Gd2O3 content using CASMO5 and SIMULATE5. A Golang-based tool, named CoreOptimizer, was developed to automate the input file generation, simulation execution and output data extraction, enabling efficient core optimization. The resulting core design meets safety and performance criteria. This paper describes the optimization process, the applied tools and discusses the key neutronic and safety characteristics of the optimized equilibrium core design.
These authors contributed equally to this work.
© Y. Song and V.H. Sanchez-Espinoza, Published by EDP Sciences, 2026
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
