The following are questions and answers on the Japanese government's plan to release treated radioactive water from the crippled Fukushima Daiichi nuclear plant into the sea.
Q: What is the current situation at the Fukushima plant?
A: Struck by a magnitude-9.0 earthquake and ensuing tsunami that hit Japan's northeast on March 11, 2011, the No. 1-3 reactors at the plant suffered core meltdowns, prompting more than 160,000 people around the complex to evacuate at one point.
Although plant operator Tokyo Electric Power Company Holdings Inc. plans to decommission the destroyed complex between 2041 and 2051, how to dispose of some 1.25 million tons of low-toxicity radioactive water accumulated in tanks on the premises has been one of the major challenges in the process.
Q: What exactly is the treated radioactive water?
A: The plant continues to generate massive amounts of radiation-tainted water that is used to cool melted nuclear fuel, together with groundwater that sweeps into its facilities.
The water is treated using an advanced liquid processing system, or ALPS, to remove most contaminants, but the process cannot get rid of tritium, which is difficult to separate from water.
Q: What is tritium?
A: Tritium is a byproduct of nuclear reactors, but exists in the natural world. It is said to pose little risk to human health and the ecosystem as the material does not present an external exposure even when water containing it comes in contact with skin. Even if one drinks the water, as long as the tritium concentration is low, the amounts of tritium will not accumulate in the body and will soon be excreted.
Q: Why does the treated water need to be disposed?
A: With the amount of water increasing roughly by 140 tons a day, the total volume kept in more than 1,000 tanks on the Fukushima complex's premises reached 1.25 million tons as of March. The storage capacity of water tanks is expected to run out as early as the fall of 2022. TEPCO claims the entire decommissioning process will be hampered if it needs to keep building storage tanks within the premises.
Q: How will the treated water be dealt with?
A: The water is diluted with seawater to lower its tritium levels below government standards -- a practice common in the industry at home and abroad.
Q: What do fishermen think of the release?
A: The government's decision has been delayed due to strong opposition from local fishermen amid concerns about the perceived safety of marine products seen in the aftermath of the 2011 nuclear crisis.
Q: How does the international community view the release?
A: The International Atomic Energy Agency has supported the plan, with Director General Rafael Grossi saying in an interview with Kyodo News late last year the organization is prepared to send a monitoring team, should it be requested.
However, neighboring China, South Korea and Taiwan, which continue to restrict imports of Japanese agricultural and fishery products from areas around Fukushima, have voiced concerns about the possible negative impact on people's health and fishery businesses resulting from the release.