Explained: why Japan is pumping water from Fukushima nuclear plant into Pacific Ocean

Japan’s decision to release water from the Fukushima nuclear power plant has been greeted with horror by the local fishing industry as well as China and several Pacific Island states.

Japan remains steadfast in its assurance that the water is safe. The discharge process, which will take 30 years, was approved by the International Atomic Energy Agency – the intergovernmental organisation that develops safety standards for managing radioactive waste.

Seawater samples taken following the water’s release showed radioactivity levels more than seven times lower than the drinking water limit set by the World Health Organization.

In 2011, a magnitude 9.0 earthquake off the northeastern coast of Japan’s main island, Honshu, triggered a tsunami that devastated many coastal areas of the country. Tsunami waves knocked out the Fukushima nuclear power plant’s backup electricity supply and caused meltdowns in three of its reactors.

Since the accident, water has been used to cool the damaged reactors. But, as the reactor core contains numerous radioactive elements the cooling water has become contaminated.

The tainted water is stored in more than 1,000 steel tanks at the power plant and now Japan says it needs the space taken by the tanks to build new facilities to decommission the nuclear plant.

While the water has been treated to remove most of the radioactive contaminants – but traces of the radioactive isotope tritium remain. Removing tritium is challenging so the water is being diluted before release. This has led to concerns about the effect on ocean waters, marine life and humans of constant exposure to tritium, even if in low concentration, over the next 30 years.

(With PTI inputs)