The amount of radiation released by the Fukushima Daiichi nuclear power plant after the March 11 earthquake and tsunami could have been more than double the original estimate by Tokyo Electric Power Co. (TEPCO), Japan's nuclear safety agency said in the Guardian newspaper.
The Nuclear and Industrial Safety Agency (NISA) also reportedly said molten nuclear fuel dropped to the bottom of the pressure vessel in the No 1 reactor within five hours of the accident, 10 hours earlier than previously thought.
By the end of last week, radiation levels inside the reactor had reportedly risen to 4,000 millisieverts per hour, the highest atmospheric reading inside the plant since the disaster.
According to the latest estimates, 770,000 terabequerels of radiation seeped from the plant in the week after the tsunami, more than double the initial estimate of 370,000.
A university researcher reportedly said a small amount of plutonium had been identified a mile from the front gate of the Fukushima plant.
It is the first time plutonium thought to have originated from the complex has been detected in soil outside its grounds, the article said.
The Japanese government June 7 released a report saying that it would overhaul regulation of nuclear power in the wake of the nuclear disaster at Fukushima, according to Reuters.
Specifically, the government said in its report to the International Atomic Energy Agency (IAEA) that it would:
• Separate NISA, which oversees nuclear power plants, from the trade ministry, which promotes nuclear power,
• Strengthen measures against earthquakes and tsunamis and secure multiple sources of power at nuclear power plants so that cooling functions aren’t lost during natural disasters,
• Review nuclear accident management policies, which had not been updated in 20 years, and require plant operators to implement accident management measures,
• Improve management of radiation exposure for workers on the site of nuclear accidents,
• Require utilities to strengthen containment venting systems in reactors and install equipment to release hydrogen to prevent a repeat of explosions like at Fukushima,
• Provide fuller disclosure of information in future accidents, including a discussion of risk factors.
It is unknown when NISA will become independent and how it will be staffed. Costs to implement the new safety measures are also unknown, Reuters said.
The IAEA reportedly told Japan in 2007 it needed to reform its system of nuclear regulation so that the agency overseeing nuclear safety is separate of the ministry charged with promoting it.
NISA also announced new safety measures that utilities will have to show by the end of June how they will be enforced, the article said.
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