[en] We have developed a new silicon irradiation holder with a neutron filter to increase the irradiation efficiency. The neutron filter is made of an alloy of aluminum and B_4C particles. We fabricated a new holder based on the results of design analyses. This filter has limited use in applications requiring prolonged use due to a decrease in the amount of "1"0B in B_4C particles. We investigated the influence of "1"0B reduction on doping distribution in a silicon ingot by using the Monte Carlo Code MVP. - Highlights: • We developed and fabricated a new silicon irradiation holder with a neutron filter at the JRR-3. • Design analyses of the irradiation holder were investigated by using the Monte Carlo code (MVP code). • We investigated the influence of "1"0B reduction in the filter on doping distribution under long-term use by the MVP code.