What is the impact of Japan’s nuclear sewage discharge into the sea? Satellite perspective fully revealed

The Japanese government held a cabinet meeting on the 13th and officially decided that the nuclear sewage from the Fukushima Daiichi Nuclear Power Plant will be discharged into the sea after being filtered and diluted. How is nuclear sewage produced? What are the impacts of sewage discharge to the sea? Sike analyzes this emission incident that has affected the world’s attention through the perspective of satellites.

The nuclear waste water storage tanks in the Fukushima Daiichi Nuclear Power Plant are densely arranged. Satellite data source: MAXAR

How did this “disaster” happen?

Turning the hour hand back to March 11, 2011, a huge earthquake hit the northeastern coast of Japan. The earthquake and subsequent tsunami triggered a nuclear leak at the Fukushima Daiichi Nuclear Power Plant operated by Tokyo Electric Power Company.

This is one of the most serious nuclear accidents in the world so far. The accident caused a large amount of radioactive material to leak, which has had a profound impact on the marine environment, food safety and human health. So far, an area of ​​337 square kilometers has been designated as an “evacuation zone”, and about 36,000 original residents have yet to return to their homes.

A satellite photo taken on March 14, 2011: Thick smoke erupted from the explosion of the №3 reactor of the Fukushima Daiichi Nuclear Power Plant in Japan. Image source: Xinhua/AFP

More than 10 years have passed since the Fukushima nuclear accident in Japan, but its nuclear sewage treatment problem has not yet been resolved. According to analysis by Japanese media, the Japanese government decided to discharge nuclear sewage because the storage tank capacity of the Fukushima Daiichi Nuclear Power Plant is about to reach the upper limit.

How is nuclear sewage produced?

There are three main sources of radioactive waste water from the Fukushima Nuclear Power Station: the original coolant in the reactor, the newly injected water for continuous cooling of the core after the accident, a large amount of groundwater and rainwater that infiltrated the reactor.

After a radiation leak, in order to control the temperature of the reactor, it is necessary to continuously inject water for cooling. Although nuclear waste water can be used for circulating cooling, due to the sea and low terrain of the Fukushima nuclear power plant, groundwater and rainwater continue to infiltrate, so nuclear waste water becomes more and more The more.

On March 11, 2011, the great earthquake in Japan triggered a nuclear leak at the Fukushima Nuclear Power Plant. Image source: Associated Press

In order to store nuclear sewage, Tokyo Electric Power has prepared a total of about 1,000 water storage tanks, 90% of which are currently full. The total capacity of all water storage facilities is approximately 1.37 million tons, which is expected to reach its limit in the fall of 2022. Thousands of densely packed circular water storage tanks are placed in the plant area, which can be clearly observed with satellite images.

The satellite photos of the Fukushima Daiichi Nuclear Power Plant in Japan taken on March 19, 2011 and March 9, 2019, show a clear contrast. Satellite data source: MAXAR

Japan’s “Yomiuri Shimbun” reported that Tokyo Electric Power Company is now adding 140 tons of “treated water” every day, and it is estimated that by September 2022, it will reach the upper limit of 1.37 million tons of storage tanks. Japan has “unable to bear” so much nuclear waste water.

What is the impact of pollutant discharge into the sea?

Since 2013, the Japanese government has evaluated five types of post-treatment wastewater treatment options: formation injection, discharge into the ocean, steam release, hydrogen release, and underground burial.

In February 2020, the ALPS Purified Water Treatment Subcommittee released the evaluation report of the wastewater treatment program after the Fukushima nuclear accident in Japan. It concluded that both discharge into the ocean and steam release are feasible solutions, and the discharge into the ocean is more convenient. Others The disposal plan is poor in terms of economy, technical maturity or time.

Fukushima Daiichi Nuclear Power Plant in Japan aerial photographed on August 20, 2013. Xinhua News Agency / Midland

What impact will sewage containing radioactive materials have if it is discharged into the sea? First, the waters off the Pacific coast of Japan will be affected, especially some waters around Fukushima Prefecture. After that, sewage will also pollute the East China Sea.

The German Marine Science Institute pointed out that the coast of Fukushima has the strongest ocean currents in the world. Within 57 days from the date of discharge, radioactive materials will spread to most of the Pacific Ocean, and in 10 years will spread to the world’s waters. Greenpeace nuclear experts pointed out that the carbon 14 contained in Japanese nuclear waste water is dangerous for thousands of years and may cause genetic damage.

A simulated rendering of German marine scientific research on the diffusion rate and impact of nuclear sewage. It can be seen from the picture that radioactive materials will continue to spread over time, and then spread to the global sea. Source: GEOMAR

A Japanese scholar pointed out that the ocean around Fukushima is not only a fishing ground for local fishermen, but also a part of the Pacific Ocean and even the global ocean. The discharge of nuclear sewage into the ocean will affect global fish migration, deep-sea fisheries, human health, ecological security, etc. In all respects, this issue is not just a domestic issue in Japan, but an international issue involving global marine ecology and environmental security.

According to satellite images in August 2020, it can be found that the sewage tank only occupies a piece of space around the Fukushima nuclear power plant, and there is still an area around it that can be developed to store wastewater.

Fukushima Nuclear Power Plant and its surroundings taken on August 29, 2020, Gaofen-2. It can be seen from the satellite image that there is still a large area of ​​open space around, and the sewage tank is a little rusty. Satellite data source: Gaofen-2

Some analysts say that from satellite images, it can be seen that the earliest batch of wastewater tanks have been rusted and stained, and it will be a matter of time to replace them. This is also a big expense. The Japanese government discharges nuclear sewage into the ocean not because of lack of space, but It is unwilling to bear the maintenance cost.

Regarding how to dispose of nuclear wastewater, Liu Xinhua, chief expert of the Nuclear and Radiation Safety Center of the Ministry of Ecology and Environment, believes that the Japanese government should adopt wastewater treatment technologies and devices with high decontamination factors to further purify and treat the excess nuclides and reduce the radioactivity in the treated wastewater as much as possible. Nuclide content; research on tritium treatment technology, and promptly disclose the research progress and results, if feasible technology should be used for the treatment of tritium in wastewater immediately.

A panoramic view of the Fukushima Daiichi Nuclear Power Plant and its sewage storage tank. Image source: Xinhua News Agency/Reuters

Greenpeace suggested that in order to avoid the continuous increase of nuclear radiation pollution of wastewater, air-conditioning should be used to replace the existing water cooling when cooling nuclear fuel rod fragments; in the face of the problem of continuous groundwater infiltration, a moat should be built at the current site of the Fukushima Daiichi Nuclear Power Plant to block groundwater.