THE Japanese Government will allow TEPCO to discharge treated wastewater stored at the Fukushima Daiichi nuclear site, into the sea, in two years’ time.
Industry has welcomed the announcement, while environmentalists and human rights proponents have voiced their opposition.
Following the 2011 nuclear accident at the Fukushima site, which saw the meltdown of three reactor units, water is constantly being used to cool the melted cores. This contaminated water is treated to reduce the concentrations of radioactive molecules, and then stored. As of 18 March, 1.25m m3 of treated water is stored at Fukushima. Storage capacity is limited to 1.37m m3 (including capacity that will be repurposed), and it is expected to run out in 2022.
According to the Government, discharge into the sea is the most reliable of the options investigated. Previously, TEPCO released a report on two potential methods for disposal – discharge into the sea and vapour release.
After sufficient treatment, the water meets regulatory standards for discharge, except in the case of tritium, an isotope of hydrogen that emits weak radiation. Tritium in the treated water remains at more than 800,000 Bq/L, where the regulatory limit for discharge into the sea is 60,000 Bq/L.
According to Government, “no technologies have been judged as being close to practical use” for removal of tritium at the nuclear power station, and IAEA published a similar view in an April 2020 report. To meet regulatory standards for discharge, the water will be diluted to a maximum of 1,500 Bq/L of tritium using seawater. No further technical detail has been offered so far.
Martin Hind, a Technical Consultant for water company MWH Treatment, and a Member of IChemE’s Water Special Interest Group, explained that “diluting it and then dumping it in the sea doesn’t really make a lot of sense because the biggest dilution event is when you put it in the sea.
“If it’s released over several years, then you may not detect the problem, as the tritium will be dispersed. Within probably a few hundred metres of the injection point it will be diluted down to the discharge standards. If you dump it all in one go, then it could be devastating.”
Hind further highlighted that “if you look at the mass of tritium that’s released, whether you dilute it or not is a bit irrelevant, you’re still dumping the same mass of tritium into the ocean. The approach from various environmental regulators…they don’t accept dilution as a treatment in itself.
“[They] would be concerned about bio-accumulation within aquatic life and potential risks to human health in the event that contaminated fish are consumed.”
According to policy, the total amount of tritium discharged will be below the operational target value of the nuclear station prior to the accident – 22trn Bq/y.
Over the next two years before implementing preparatory work and commencing with the discharge, TEPCO will develop and submit a detailed plan for approval by Japan’s Nuclear Regulatory Authority. The company will have to comply with regulatory standards based on recommendations from radiation protection organisation International Commission on Radiological Protection (ICPR).
The (IAEA) has welcomed Japan’s decision.
IAEA General Director Rafael Mariano Grossi said that discharge into the sea is technically feasible and in line with international practice – though the amount of water makes the situation unique and complex. He added that the decision is a milestone that will allow decommissioning of the site to continue.
Greenpeace Japan has condemned the decision, saying it “completely disregards the human rights and interests of the people in Fukushima, wider Japan, and the Asia-Pacific region”. UN human rights experts have previously warned of the risks posed to the environment and to human rights.
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