A Framework for Fuel Damage Ratio Calculation in Spent Nuclear Fuel Transportation

Yeongjun Son, Seyeon Kim, Sanghoon Lee^*

Department of Mechanical Engineering, Keimyung University, Dalgubeol-daero 1095, Dalseo-gu, Daegu 42601, Korea

Received 2025-01-13 ; Revised 2025-02-07 ; Approved 2025-02-25

Abstract

For risk assessment of spent nuclear fuel (SNF) transportation, it is necessary to calculate the damage ratio of SNF rods loaded in the cask. Due to the complexity in the geometry and material properties of SNF, it is impractical to analyze the detailed behavior of every fuel rod and assembly in a single cask model. This study presents a framework for performing cask-level analysis by sequentially simplifying the fuel rods and spent fuel assemblies for fuel damage ratio (FDR) calculation. Using the simplified fuel rod model developed in previous studies, we constructed a CE 16x16 fuel assembly model and presented a methodology to simplify the CE 16x16 assembly model into cuboids. Cask drop analyses were performed to validate the similarity of the detailed CE 16 x 16 model and the simplified model. Using the proposed simplified models, a procedure for quantifying the bending load and pinch load applied to the fuel rods during the drop impact is presented. The FDR can then be calculated by comparing the quantified loads with their respective failure criteria. Through a case study, the feasibility of the developed framework for systematic and accurate FDR calculation was effectively demonstrated.

Key Words : Spent Nuclear Fuel, Risk assessment, Simplified Model, Impact Acceleration, Fuel Damage Ratio