At the end of August, Tokyo Electric Power Company (Tepco), which maintains the Fukushima Daiichi NPP, began releasing water into the Pacific Ocean. To cool the reactors during the core meltdowns that resulted from damage caused by the 2011 earthquake and tsunami, water was taken from the Pacific. After use, it was treated to remove most radionuclides and stored sealed tanks. In addition, the nuclear units collect and isolate groundwater and rainwater that becomes contaminated and need treatment. More than 1m tonnes of treated water has accumulated at the station, which still contains tritium that the ALPS technology (advanced liquid processing system) cannot remove. According to Japanese nuclear plans, this water will be diluted to safe levels and discharged to the sea over about 30 years. And although the project was approved by IAEA experts, neighbouring countries and the fishing industry are opposing the plan.
The ALPS system removes 62 types of radionuclides, except for tritium (3H), a radioactive isotope of hydrogen. In addition, carbon-14 (C-14), potassium-40 (K-40), strontium-90 (Sr-90), iodine-129 (I- 129), and some isotopes of caesium (Cs) and plutonium (Pu) remain in the water, albeit in smaller quantities. More than a thousand of tanks are located at the Fukushima site containing 1.34m tonnes of water and there is no further capacity. In 2013, Tepco began discussing plans to release the tritium water into the Pacific Ocean, which met with strong opposition from the scientific community, environmentalists and politicians in neighbouring countries: China, South Korea, Russia, and even in Japan itself. It took more than 10 years to convince key opponents that the solution was safe.
In July the International Atomic Energy Agency (IAEA) released a final report in which they approved the water discharge scheme, which began in August. The trial stage lasted 17 days, with 7,800 cubic metres of treated water being discharged. The planned volume for release by the end of March 2024 is 31,200 tonnes. The tritium concentration in the discharged water is 5,000bn Becquerels (Bq).
On 1 September, Tepco first detected the presence of tritium in sea waters on the northeastern border of the port adjacent to the station at a level of 10 Bq/litre – the permissible limit is a thousand times higher. Previously, Tepco set a limit of 700 Bq/litre above which the discharge of water would stop.
There were mass protests including mass mailings on social media in South Korea and Japan. At the official objections were raised by China including bans on seafood imports from 10 Japanese prefectures. Taiwanese authorities also expressed concern. The South Korean leadership also opposed the original plan to dump water but changed its position after the publication of the IAEA report.
“The concerns of the public in a number of countries, including Russia, from my point of view, are justified,” says Valery Menshchikov, a member of the board of the Centre for Environmental Policy of Russia and the public council of Rosatom. “If the discharge of treated water was a one-time event, there would be no alarm…. But the trouble is that more than 1m tonnes of contaminated water have accumulated at the station, and the discharge will continue for at least 10 years. In this case, up to approximately 1,000bn Bq of tritium will enter the ocean. It seems that Japan is setting up a global experiment on the influence of such a volume of isotopes on the marine environment and the creatures living in it.”
He added: “First of all, it is necessary to analyse the consequences of possible radioactive contamination of fish. Ichthyologists note that the accumulation of excess radioactivity will primarily affect long-lived fish. The effect of low and ultra-low doses of radiation on human health has not been fully studied.”
According to Oleg Tashlykov, Professor at the Department of NPPs and Renewable Energy Sources of the Ural Federal University, “The tritium content indicated for discharged water is not dangerous due to its relatively weak radiation characteristics. However, there is no reliable information about the concentration of tritium in certain algae, plankton and other ocean creatures that can be food for fish and other marine life – and they may end up on our table. The justification that water with tritium will still be diluted many times with ocean water does not provide complete confidence in the safety of this method.”
However, there is an alternative to dumping thousands of tonnes of water with tritium into the ocean. Before Fukushima, Russia set up a demonstration pilot plant for purifying tritium water (it is now at the Leningrad NPP as a museum exhibit). Unfortunately, the productivity was clearly insufficient – up to 10 cubic metres a day and Japanese nuclear scientists rejected the proposal.
In 2019, Canada's Laker TRF said it had developed AWD (advanced water distillation) technology that would make water treatment at the Fukushima Daiichi Nuclear Power Plant cost-effective and reliable. However, the industrial application of this technology at the station was never developed.
Tashlykov says a significant part of the water containing tritium can be used directly at the Fukushima site (subject to strict compliance with sanitary standards and regulations) for the manufacture of concrete products and structures: road slabs, buildings for radioactive waste storage facilities, etc. The permissible content of tritium in concrete products and structures is an order of magnitude higher than in water, he notes.
Cobalt, which is also contained in treated Fukushima water, can be converted from a liquid to a solid state. Physicists from the Ural Federal University participated in improving radiation protection for the technology of conditioning liquid radioactive waste (LRW), invented by Ural scientists. They designed a container for solidified liquid radioactive waste with long-lived Cs-137 and Co-60. The containers reduce radiation to a safe level; one such container can replace five or six regular ones, the university said in a statement. There was no response to this proposal from Japanese colleagues. And Tepco refused the university nuclear workers’ request to provide samples of ocean water from the waters of Fukushima Prefecture.
“Any restriction in the provision of information, and especially the denial of the possibility of direct control and sampling, causes distrust and doubt about the objectivity of the information provided by the Japanese side,” notes Tashlykov. “And this mistrust is strengthened by the fact that the actions of the Japanese side to prevent and limit the development of the accident shown by their reluctance to accept advice and assistance from specialists from Russia.”
Scientists from the Far Eastern Branch of the Russian Academy of Sciences (FEB RAS) propose organising monitoring of the consequences of discharges from the Fukushima-1 nuclear power plant. “We believe that it is necessary to assemble a commission from members of the Far Eastern Branch of the Russian Academy of Sciences. We need to formulate a programme by 1 by November, said Ilyicheva Grigory Dolgikh, Academician of the Russian Academy of Sciences and Director of the Pacific Oceanological Institute. “We assume that it is necessary to include sea expeditions to the Kamchatka Peninsula and the Kuril Islands, as well as to those areas of the water area where there are fish that later come to our waters.” He added that he believes it is also necessary to organise monitoring in the atmosphere using laser locators – lidars.
Image courtesy of Rosatom
