Twelve years after a powerful earthquake and ensuing tsunami destroyed the Fukushima Daiichi Nuclear Power Station, the plant's operator, Tokyo Electric Power Company (TEPCO), has decided to finally get rid of the wastewater from the cooling process. More than 1.3 million cubic metres of seawater were sprayed onto the damaged cores to keep them from overheating. TEPCO has decided that the time as come to dispose of the water, a necessary step in the decommissioning of the plant.
Prior to its release, the wastewater was subjected to a filtration process (ALPS) to remove all the radioactive elements except tritium. Tritium (H-3) is a radioactive isotope of hydrogen and always present in water (H2O). A tritium atom has a nucleus of one proton and two neutrons, whereas the nucleus of the common isotope hydrogen contains one proton and zero neutrons. The heavy nucleus makes tritium unstable and therefore radioactive.
The ALPS-treated water is stored in tanks which are regularly monitored to prevent leaks. The water will be diluted with a large volume of seawater, then released into the Pacific Ocean via a 1-km long discharge tunnel, gradually over a period of 30 years.
Will the discharged water be dangerous to humans? To Fish?
TEPCO says there is no danger.
The released water will contain a lower proportion of tritium than water discharged by a nuclear power station in normal operation. It will have a radioactivity level of around 1,500 Bq/L (becquerels per litre), well below the threshold value set for drinking water by the World Health Organisation (WHO) which is 10,000 Bq/L.
Tritium occurs naturally in trace amounts in seawater and the atmosphere. It emits low-energy beta particles (fast moving electrons) and has a half life of 12.3 years. For decades, trace amounts of tritium have been released regularly into water from operating nuclear power plants around the world, with no measurable impact on the environment or health.
The IAEA says the water is safe.
The IAEA (International Atomic Energy Agency, the UN agency responsible for nuclear safety) says the discharge presents no danger to health.
Rafael Mariano Grossi, Director General of the IAEA, has said, “The IAEA has concluded that the approach and activities to the discharge of ALPS treated water taken by Japan are consistent with relevant international safety standards.... Furthermore, the IAEA notes the controlled, gradual discharges of the treated water to the sea, as currently planned and assessed by TEPCO, would have a negligible radiological impact on people and the environment.”
The Japanese Trade and Industry Minister Yasutoshi Nishimura, gave this reassurance:
"We will continue to conduct analysis every day over the next one month and even after that, maintain our analysis effort."
Thus, a final chapter on a disastrous accident will come to a close.