The Chinese customs announced on Friday, that China will impose a ban on food imports from nearly one-fifth of Japanese prefectures. They have cited China’s concern over Japan’s decision to discharge nuclear-contaminated water from the defunct Fukushima powerplant into the sea.

Source: World Nuclear News
China, the Nuclear Watchdog
The customs stated that China, which is the largest importer of Japanese seafood, would also strictly review the documents, with special stress on seafood products, from other parts of Japan as well.
China customs said that they are committed to strengthening the detection and monitoring of nuclear and radioactive substances. They claim that their decision to ban imports from 10 Japanese prefectures is in keeping with this aim.
In the last few weeks, they have been quite vocal about Japan’s move to discharge the contaminated water into the sea, and although, the U.N. nuclear watchdog, the International Atomic Energy Agency (IAEA), endorsed Japan’s decision, citing that it is safe to do so, China does not seem to be convinced.
The customs said that they do not believe that the report fully included the views of all the experts involved in the assessment process and hence it can not be considered a unanimous decision among the experts and is an “one-sided” report.
The Chinese have criticized Japan for using the ocean as its “private sewer”.
Experts not on the same page over Japan
The Fukushima Daiichi powerplant, ran by the Tokyo Electric Power Co (Tepco), was severely crippled by the 2011 Tsunami. Since then, more than a million tonnes of wastewater have been accumulated there.

Source: BBC
Since the disaster, Tepco has been pumping in water to cool down the nuclear reactor’s fuel rods in the power plant. They have been storing this water in large tanks. Now that more than 1,000 tanks have been filled, Japan believes that this is not a sustainable solution and has decided to gradually release the water into the Pacific Ocean for 30 years, insisting it is safe.
Since this decision was made two years ago, the plan has been controversial even in Japan as local communities expressed fears over contamination. Fishing and seafood industry groups also voiced concerns over suffering severe economic loss as people would not buy seafood out of fear.
In recent developments, Japan’s nuclear regulator granted approval to Tepco on Friday. With this approval, along with IAEA’s nod, Japan can now begin the process.
Discharging by-product water into the ocean has been a normal practice for powerplants all over the world, however, this being the result of a natural disaster, has given rise to concerns.
Tepco filters the contaminated water with its Advanced Liquid Processing System (ALPS) which reduces the radioactive content to acceptable safety standards, apart from tritium and carbon-14.
Tritium and Carbon-14 are radioactive variations of hydrogen and carbon respectively, which are very difficult to separate from water. They emit very low levels of radiation, however, can be hazardous if consumed in large amounts.
Many scientists who back the plan claim that the discharge will be like a drop in the ocean, whose effect will be negligible. However, other critics opined that Japan should, for the time being, keep storing the water in tanks.
Some scientists believe that more studies should be conducted regarding how the plan could affect aquatic life.