Tokyo: Eight radioactive substances have been identified in stagnant water in the basement part of the Fukushima Nuclear Power Plant in Japan.

The analysis, released on Saturday, by the Nuclear and Industrial Safety Agency showed that the highest levels found in the water in block 1 of the plant were of Caesium 137, a radioactive isotope that was released into the environment in the Chernobyl disaster. It appeared at levels of 1.8 million Becquerel.

Caesium 137, in contrast to radioactive iodine, has a relatively long half life of 30.2 years. It is created during nuclear fission. The water also contained Caesium isotopes 134 and 136 as well as iodine-131.

Tokyo Electric Power Co (TEPCO) has vowed to clear the water as quickly as possible to allow workers to continue efforts to cool the reactors.

Three workers, who were working to restore cooling functions at reactor 3, were exposed to radiation levels in water that was 10,000 times the normal level, TEPCO, the plant's operator, said on Friday.

Seventeen workers at the plant have been contaminated since the plant was damaged in a March 11 earthquake and resulting tsunami, a news agency reported on Saturday.