A new report on the Fukushima nuclear plant disaster from last March indicates that the amount of radiation it released into the atmosphere was actually more than double the magnitude originally estimated.

The Norwegian Institute for Air Research (NIAR) said that level of radioactive Caesium-137 released into the air from the crippled plant amounted to about 36,000 terabecquerels, versus the Japanese government’s initial estimate of 15,000 terabecquerels of Caesium.

However, the 36,000 figure is significantly lower than the 90,000 terabecquerels released by the Chernobyl catastrophe in the 1980s in Ukraine.

Caesium-137 is a slow-decaying element which can last for three decades in the environment and produce cancer-causing radiation.

Japan’s own Nuclear and Industrial Safety Agency did not comment on NIAR’s findings since it has not reviewed its contents.

According to reports, the difference between the Japanese government’s survey and the NIAR study might be attributable to the fact that Tokyo officials likely did not account for emissions that blew out into the sea. Reportedly, about 20 percent of the Caesium fell onto the Japanese land mass, while most of the remainder settled in the Pacific Ocean -- making it the single worst nuclear contamination of the sea in history.

The Institute for Radiological Protection and Nuclear Safety, France's nuclear monitor, stated: This is the biggest single outflow of man-made radionuclides to the marine environment ever observed.”

The NIAR report did not discuss the long-term health implications of the radiation release.

Meanwhile, Japanese nuclear officials are still seeking to control the damaged Fukushima plant, with an eye towards achieving a cold shutdown by year-end.