Radiation readings around tanks holding contaminated water at the crippled Fukushima nuclear plant have spiked by more than a fifth to their highest levels, Japan’s nuclear regulator said, heightening concerns about the clean-up of the worst atomic disaster in almost three decades.
Radiation hotspots have spread to three holding areas for hundreds of hastily built tanks storing water contaminated by being flushed over three reactors that melted down at the Fukushima Daiichi plant in March 2011.
The rising radiation levels and leaks at the plant have prompted international alarm, and the Japanese government said late on Tuesday it would step in with almost $500 million of funding to fix the growing levels of contaminated water at the plant.
Readings just above the ground near a set of tanks at the plant showed radiation as high as 2,200 millisieverts (mSv), the Nuclear Regulation Authority (NRA) said yesterday. The previous high in areas holding the tanks was the 1,800 mSv recorded on Saturday. Both levels would be enough to kill an unprotected person within hours.
The NRA has said the recently discovered hotspots are highly concentrated and easily shielded. The tanks sit on a hill above the Pacific Ocean at the Fukushima plant, which was devastated by a massive earthquake and tsunami in March 2011, triggering the worst nuclear crisis since Chernobyl a quarter of a century earlier.
The plant operator, Tokyo Electric Power Co, or Tepco, said last month water from one the tanks was leaking.
Another small leak was found later and the rising number of areas of concentrated radiation are raising concerns of further leaks.
The NRA later raised the severity of the initial leak from a level 1 “anomaly” to a level 3 “serious incident” on an international scale of 1-7 for radiation releases.
“There’s a strong possibility these tanks also leaked, or had leaked previously,” said Hiroaki Koide, Assistant Professor at Kyoto University Research Reactor Institute.
“We have to worry about the impact on nearby groundwater. These tanks are not sturdy and have been a problem since they were constructed two years ago.”
It is also possible the radiation readings are increasing because of more frequent monitoring and inspections by Tepco employees, indicating the hotspots and leaks have been there for some time, Koide said.
“The government has finally said they will be involved in this problem but they are still not going to be fully involved in the decommission,” he said. “It is too little, too late.”
The disaster created fuel-rod meltdowns at three reactors, radioactive contamination of the air, sea and food and resulted in the evacuation of 160,000 people north of Tokyo.
The peak release of radiation in the sea around Fukushima came about a month after the earthquake and tsunami. Ocean currents have since dispersed the plume.