An active-to-sterile neutrino oscillation with an eV-scale mass state has been suggested from 2020/3/16-19 名古屋大学 Copyright © 2020 JPS 129 19aG20-5 systematic precision. It also provides an opportunity of measuring spectrum evolution for changes in ratio of major fissile isotopes during a fuel burnup cycle of a single low-enriched-uranium fuel reactor. The measurement is expected to be completed in July 2020, acquiring data for one full reactor operation cycle period and for two reactor maintenance period before and after the operation cycle.