S K Nag
On March 11, 2011, a massive earthquake followed by a tsunami hit Japan’s coast severely. The Fukushima Daiichi nuclear plant on Japan’s Pacific coast suffered huge damage, and eventually had to be junked forever. The accident was the second-worst in the history of nuclear power generation after Chernobyl.
The tsunami — 17 metres (56 feet) high — slammed into the coastal plant, destroying its power supply and cooling systems and causing meltdowns at reactors 1, 2 and 3. The plant’s three other reactors were offline and survived. A fourth building, along with two of the three melted reactors, had hydrogen explosions, spewing massive radiation and causing long-term contamination in the area. The immediate and long-term radioactive pollution across the globe was a big challenge, and Japan is fighting it today and will have to in the future as well.
This April, the Japanese government decided to release 1.25 million tonnes of treated but still radioactive water stored in tanks into the Pacific Ocean. Prime Minister Yoshihide Suga said, “Releasing the treated water into the sea is a realistic solution,” and that disposing of the water is needed to complete the decades-long decommissioning of the Fukushima plant. He said the government would work to make sure the water is safe and help local agriculture, fisheries and tourism.
Under the basic plan, plant operator Tokyo Electric Power Co (TEPCO) would start releasing the water in about two years after building a facility and compiling release plans that follow safety requirements. This might take 40 years to complete. It said the disposal of the water cannot be postponed further and is necessary to improve the environment surrounding the plant for the safety of the residents there.
Japan, an island country, consists of five main islands — Hokkaido, Honshu, Kyushu, Shikoku, Okinawa — and 6,847 other small remotely located islands amid the Pacific Ocean. It has the 6th longest coastline of 29,751 km. In the 12th Century, Japan started reclaiming land from the sea and river delta. The process was expedited post World War II to support its economic growth.
Currently, 0.5% of the country’s area is reclaimed land. Largely, this reclamation supported marine and industrial ecosystems, such as Higashi, Ogishima (Kawasaki), Osaka Bay and Nagasaki Airport, to excel. Japan has also reclaimed some artificial islands to build Chubu Centrair International Airport, Kansai International Airport, Yokohama Hakkeijima Sea Paradise and Wakayama Marina City.
Due to proximity to volcano and location in the Pacific deep, Japan is highly prone to frequent earthquakes. So it has age-old experience of land reclamation in a highly seismic area. Then what went wrong with the Fukushima land reclamation design that could not stop the flooding of the nuclear plant?
10 Years Ago
The earthquake, known as the Great East Japan Earthquake or the 2011 Tohoku earthquake, struck east of Sendai, 97 km north of the plant. The epicentre being near Honshu, Japan’s main island, produced maximum ground force exceeding the seismic design tolerance of reactor units 2, 3 and 5. The earthquake force stopped the operating unit of 1, 2 & 3 suddenly, and this conk-off resulted in an abrupt power outage to the continuous cooling system required for the reactor core. The remaining three units of 4,5 & 6 were under scheduled maintenance.
Emergency diesel generators supported until tsunami submerged the generators of reactors 1-5. The remaining two undamaged power generators of reactor 6 were assigned to help the cooling system power requirement of 5 & 6, and the issue of overheating was averted, unlike reactors 1 to 4. The plant, therefore, encountered a major failure leading to its shut down.
The water level exceeded the plant’s developed ground level of 10m above sea level, flooding the entire plant and collapsing the system in totality. The development level of the reclaimed land took no heed of the tsunami warning while deciding the land level.
The plant developed multiple cracks in the three reactors leading to radioactive leakage to the flowing natural stream of groundwater in a nearby area. Continuous cooling support using water through a pumping system is required for the damaged plant, including its three defunct reactors.
Every day around 140 tonnes of contaminated water is generated from the cooling process. Around 1.25 million tonnes of radioactively spoiled water is already stored in colossal capacity silos, needing a planned release to de-risk the potential threat before any further earthquake hits the coast.
Japan’s decision to go ahead with the planned discharge of the contaminated water after necessary secondary treatment complying with global discharge norms has angered the international community. This dumping may potentially expose planetary lives to radioactive radiation from tritium and traces of other radionuclides.
Though the US has endorsed it as “transparent efforts,” China, Taiwan, South Korea, local fishery association and environmental organisations have condemned the decision. South Korea confirmed legal action under the international dispute settlement mechanism. China commented, “Japan cannot use the Pacific as its sewer.”
Besides how to dispose of the radioactive debris, holding such a massive load of contaminated water for a long time in a seismic-prone area, is the big question now.
A Long Process
Decontamination is a three-to-four-decade continuous process to bring the radioactive radiation to an acceptable limit. Any such retiring plant must undergo strict decommissioning protocols to avoid the underlying risks associated with radioactive waste, requiring planned disposal to prevent a catastrophic disaster to the planet.
Despite public protests, in many parts of the world, including India, nuclear energy use is pronounced and significant. Globally, nuclear power contributes around 4% to the energy use. While India accounts for 2.42%, Japan falls under the 4% category of nuclear power generation.
In routine operation, water is required to cool the reactors that never come in contact with the radioactive fuel in the reactor core. This used cooling system water can be discharged to an open environment without impacting the environment. But cracks in the Fukushima reactors resulting from the earthquake are contaminating the cooling water with radioactive energy. Moreover, the cracks have led to leakage of contaminated water, mixing with groundwater flowing towards the sea.
This unique challenge is overcome by using a super-cooler refrigerant piped into the ground around 100 feet deep, known as ‘Ice Wall’. This coolant freezes (-30 degree Celsius) the soil around it and restricts the flow of fresh groundwater towards the reactors. Some have doubted the success of this ice wall, but TEPCO claims it has produced satisfactory results.
Soon this treated radioactive water will exceed the maximum on-ground holding capacity that TEPCO can manage to build by late next year. At present, around 1,000-odd silos are built on the ground with huge capacity.
The United Nations Convention on the Law of the Sea (UNCLOS) under Article 210 and London Convention and Protocol under two international treaties and Article 8 restrict such disposal without the permission of competent states and countries that are likely to be affected.
Advanced Liquid Processing System can remove 62 radioactive elements leaving behind tritium (a less radioactive substance). Tritium is a hydrogen isotope and, therefore, difficult to separate from water.
Japan is planning to release the water by 2022 after diluting it before releasing it into the ocean. Tritium dilution level will be brought under the limit allowed so that the emitted radiation from it will not penetrate human skin. This dilution technique has been practised worldwide, argues TEPCO.
Because of the outlying islands, long coastline, extensive marine water body, Japan has abundant marine life and marine minerals, which contributed to its economy growing big, making them achieve nearly 15% of the global catch. Its exclusive economic zone is the 8th largest in the world. Marine repositories under its custody include vast marine life and marine mineral resources such as manganese, cobalt and hydrothermal deposits.
Greenpeace consequently flagged this decision “an outrage,” and Japan’s National Federation of Fisheries Cooperatives called it “utterly unacceptable.” Japan is the second-largest producer of fisheries products by quantity in the world.
However, IAEA (International Atomic Energy Agency ) Director General Rafael Mariano Grossi said the ocean discharge was in line with international practice, though “the large amount of water at the Fukushima plant makes it a unique and complex case.”
(The author is an MSME Strategist & Mentor, Energy Expert and IIM(Indore) & NTU alumnus)
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