Japanese workers will inject?a water absorbent?into the earthquake-paralyzed nuclear power plant in Fukushima Prefecture in an attempt to block the leakage of highly radioactive water into the sea, Japan's nuclear safety agency said on Sunday.

Contaminated water was seeping from a 20-centimeter crack in a concrete pit at?the No. 2?reactor, according to Nikkei.com.

Polymeric powder is a water absorbent often used in diapers.?It can absorb 50 times its volume of water. Engineers will inject the material into pipes leading to the crack.

Iodine-131, a radioactive material, was detected more than 10,000 times the legal concentration limit in the pit.

According to statistics available, in sea water near the troubled plant, the level of iodine-131 was 4,385 times the?legal limit?on Wednesday.

On Saturday afternoon, a 15-member advance party of a U.S. military radiation control team arrived at Japan to help deal with the nuclear crisis.

The nuclear plant has been spewing radioactivity since a magnitude-9.0 earthquake and ensuing tsunami hit northeast Honshu Island on March 11.