The Tokyo Electric Power Co. in a report released Tuesday said that meltdown took place at reactors Nos. 2 and 3 just as it happened at reactor No.1.

According to the report, the melted fuel is believed to have been kept cool at the bottom of the pressure vessels.

As regards the continuous meltdown, the prime minister's aide said that the government felt responsibility for its earlier hasty assessment of the situation caused by the accident.

Meanwhile, Tokyo Shimbun on May 25 said quoting an analysis by TEPCO that breaches may have occurred at containment vessels encasing the Nos. 1 and 2 reactors at the power plant, possibly causing leaks of highly radioactive water there.

The paper said that if it hypothesizes that a breach about 3 centimeters wide occurred at the No. 1 reactor's containment vessel 18 hours after the quake and it widened to about 7 cm 50 hours after the quake, that corresponds well to changes in pressure readings inside the containment vessel. The company also hypothesized that a breach roughly 10 cm wide occurred at the No. 2 reactor's containment vessel 21 hours after the quake due to elevated temperatures, among other factors, finding that it also corresponds with data obtained, it said.

I t suggested that at the No. 3 reactor of the plant its main steam piping has been damaged and steam leaked from the pressure vessel.

At a time when there is growing concern due to the radiation crisis in different parts of Japan, traces of radioactive substances were detected in the air in Hokkaido.