ESTIMATED CRITICALITY LOWER-LIMIT MULTIPLICATION FACTOR OF LOW-ENRICHED URANIUM DIOXIDE-CONCRETE SYSTEM USING THE BOOTSTRAP METHODTakuto Hayashi, Fuga Nishioka, Tomohiro Endo and Akio YamamotoEPJ Web Conf., 247 (2021) 17001DOI: https://doi.org/10.1051/epjconf/202124717001