Photo : Reactor 5 and 6. Photo was taken on the 19th of June, 2015. [URL]
An overwhelming amount of pumice stones is likely to hit the Fukushima plant.
A submarine volcano of Ogasawara islands erupted from the 13th to the 15th of August, 2021. The eruption, which occurred approximately 1,300km south of Tokyo, is estimated to be the largest volcanic activity in Japan since the end of the Second World war. It simulatedly produced 100 ~ 500 million cubic meter of pumice stones and it’s already covering the beaches of other islands, which are around 1,300km away.
Fukushima nuclear plant is about 1,460km from the erupted volcano and Tepco is forced to build the shielding walls in the port of the plant as the spent fuel pools of Reactor 5 and 6 are depending on seawater. Pumice stones may damage the seawater intake equipment of the coolant system. The original shielding facility has been left crippled since the tsunami. Tepco announced the plan to install a silt fence and metal fence in the plant port.
It is not estimated when and how much pumice stones may reach the Fukushima plant.
https://www.tepco.co.jp/decommission/information/newsrelease/reference/pdf/2021/2h/rf_20211117_3.pdf