26 Août 2012
August 24, 2012
High concentrations of rust have been found in the water in the Hamaoka nuclear plant's No. 5 reactor following a seawater inflow accident last year, plant operator Chubu Electric Power Co. has announced.
An estimated five metric tons of seawater gushed into the No. 5 reactor shortly after the plant was suspended for safety checks in May last year. Before the incident, the water sampled from around 10 of the reactor's fuel assemblies registered an iron rust concentration of about 62 parts per billion (ppb). More recent testing following the accident showed concentrations as high as 8,900 ppb -- about 14,000 times greater.
Chubu Electric, which has reported its findings to the Nuclear and Industrial Safety Agency (NISA), believes that the rust may have been carried in from the outside with the seawater. NISA, meanwhile, has stated that it will "examine whether the rust originated from inside the reactor and whether it would affect its operation."
Chubu Electric began withdrawing the No. 5 reactor fuel assemblies on Aug. 22 and expects to have all 872 assemblies out of the core by the end of the month. The utility will then check the interior for corrosion.