Shikoku Electric Power Co. and Ehime Prefecture announced on April 18 that the concentration of radioactive iodine in the primary cooling water passing through the reactor at the No. 3 reactor of the Ikata Nuclear Power Plant (Ikata-cho, Ehime Prefecture) had risen to about three times the normal level. There is no external radiation impact, and the plant will continue to operate under enhanced monitoring. There is a possibility that a small hole has been made in the fuel rods and radioactive material is leaking out.
According to the prefectural government, at around 5:45 p.m. on the 18th, the iodine concentration rose to 0.25 becquerels per cubic centimeter, up from the normal level of 0.09 becquerels per cubic centimeter. This is less than 1/120,000 of the operational limit (32,000 becquerels per cubic centimeter). Shikoku Electric Power Co. has increased the number of inspections from three times a week to once every three to four hours and will continue to monitor the situation.