TOKYO — Some five tons of seawater is estimated to have entered a reactor core at the Hamaoka nuclear power station in central Japan, the operator said on Thursday. That followed the discovery of an estimated 400 tons of seawater that has inundated the main steam condenser at reactor 5 of the Hamaoka nuclear plant in Shizuoka prefecture, south-west of Tokyo.
Chubu Electric Power Co, which runs the plant, found the 400 tons of seawater while shutting down the reactor as requested by the government. Chubu Electric officials said their assessment of the purity of water inside the pressure vessel showed some 5 tons of seawater came from the condenser. The utility will not decommission the reactor. Instead, it will dilute and desalinate the seawater to prevent any corrosion inside the reactor as salt causes corrosion.
The steam condenser, designed to convert waste steam from a power-generation turbine into water, has some 64,000 tubes, each 3 centimetres in diameter, where seawater is injected to cool the steam, Jiji reported. The operator is now pumping fresh water into the pressure vessel to reduce the concentration of salt in the water to avoid corrosion of the vessel, company officials were quoted as saying by Jiji.
On May 9, Chubu Electric decided to suspend the operation of the plant located near a geological fault line after Japanese Prime Minister Naoto Kan called for the shutdown over growing public concern about another possible nuclear accident after the nuclear emergency triggered by the March 11 earthquake and tsunami.
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