Development of long life volcanic ash filters which reduce replacement frequency

New regulatory requirement of domestic nuclear power plant has been strengthened after the accident at the Fukushima Daiichi nuclear power plant. And even in the case of large-scale eruption, it has been required that there is no impact on the safety of nuclear power plants. In the Hamaoka nuclear power plant, assuming the eruption of Hakone volcano group, we are considering measures to cope with volcanic ash. The most fatal issue caused by ash falling is blockage of air conditioning filters. There are two types of filtering method against falling ash. First one is catching ash by rotating filter panel and wash into oil tank and second one is deposition of ash with static filters. Since space of the site it limited, we have chosen second approach. We simulated continuing ash fall and examined an effect on air conditioning filters. With this effort, we have established a Long Life Filter which can effectively remove falling ash for more than 7 days without replacement. (author)