These more than 20 hours gave the fuel rods enough time to melt through the steel shell, causing a steam explosion. In the end, more than 300 square kilometers were contaminated by excessive nuclear radiation.
If they put in seawater for cooling in time, although the equipment will be completely damaged, the seawater is outside the steel shell. The steel shell wraps the fuel rods, and the heat generated by the fuel rods can always be taken away by the seawater outside the steel shell. The seawater at this time will not be polluted, so there is no need to store such cooling water.#Nuclear Wastewater