Design optimization of cylindrical burnable absorber inserted into annular fuel pellets for soluble-boron-free SMR

• Published in: Nuclear engineering and technology Vol. 54; no. 4; pp. 1464 - 1470
• Main Authors: Jo, YuGwon, Shin, Ho Cheol
• Format: Journal Article
• Language: Korean
• Published: 2022
• Subjects: Spatial self-shielding effect; Soluble-boron-free; Burnable absorber; Small modular reactor; Annular fuel pellet
• ISSN: 1738-5733; 2234-358X

This paper presents a high performance burnable absorber named as CIMBA (Cylindrically Inserted and Mechanically Separated Burnable Absorber) for the soluble-boron-free SMR. The CIMBA is the cylindrical gadolinia inserted into the annular fuel pellets. Although the CIMBA utilizes the spatial self-shielding effect of the fuel material, a large reactivity upswing occurs when the gadolinia is depleted. To minimize the reactivity swing of the CIMBA-loaded FA, two approaches were investigated. One is controlling the spatial self-shielding effect of the CIMBA as burnup proceeds by a multi-layered structure of the CIMBA (ML-CIMBA) and the other is the mixed-loading of two different types of CIMBA (MIX-CIMBA). Both approaches show promising performances to minimize the reactivity swing, where the MIX-CIMBA is more preferable due to its simpler fabrication process. In conclusion, the MIX-CIMBA is expected to accelerate the commercialization of the CIMBA and can be used to achieve an optimal soluble-boron-free SMR core design.