The uncertainty of the thermal expansion of simulated fuel was evaluated based on the Monte Carlo method. The uncertainties of the thermal expansion were divided into three components: initial sample length, system calibration factor, and an iterative measurement. For each component, a normal probability distribution function was assumed and the extended uncertainty was evaluated for various samples and batches. The results were compared with an international standard guide. Furthermore, the Shapiro-Wilk test was performed to establish a normality of the estimated sample means. (C) 2006 Elsevier B.V All rights reserved.