Tokyo Electric Plans to Release Fukushima Wastewater

 

picture from TEPCO website

On March 11, 2011, a magnitude 9.1 earthquake struck off the northeast coast of Honshu, Japan, generating a deadly tsunami. Systems at the Fukushima nuclear plant detected the earthquake and automatically shut down the nuclear reactors. Emergency diesel generators automatically turned on to keep coolant pumping around the nuclear cores to try and keep them cool.

But soon after the tsunami wave which was over 46 feet high hit Fukushima. The water overwhelmed the defensive sea wall, flooding the plant and knocking out the emergency generators. Workers rushed to restore power, but in the days that followed the nuclear fuel in three of the reactors overheated and suffered a nuclear meltdown  where the nuclear cores were partly melted.

The Fukushima nuclear disaster released radioactive materials into the environment and forced thousands of people to evacuate their homes. Ever since 2011 crews have continuously pumped water through the destroyed reactors to keep the nuclear cores cool. In addition water flows naturally from the mountain towards the sea.

Approximately 150 tons of groundwater, which naturally runs from the mountain side to the ocean, flows into the reactor buildings cools the reactor cores and become newly contaminated water. Various countermeasures are taken (filtration to remove radionuclides) and storage to prevent  the contaminated water from flowing out to the port or that the contaminated water may leak from the storing tanks (secondary containment measures). 

The Tokyo Electric Power Company (TEPCO) which owns the nuclear plant has been pumping, filtering and storing the water in tanks at the plant. Now, they say that they are running out of space to store the water on land. Last summer TEPCO obtained the approval of the International Atomic energy Agency (IAEA) for a plan to begin releasing the stored water into the Pacific Ocean. The plan is to release the stored water sometime this year. 

IAEA Director General Grossi accepted Japan’s invitation and appointed a Task Force of independent experts and IAEA staff to carry out the three-pronged review – regulatory, technical and independent sampling and analysis – against international safety standards. These safety standards reflect an international consensus and serve as a global reference for protecting people and the environment from the harmful effects of ionizing radiation. In January the IAEA Task Force completed their second regulatory reviews in Japan. 

No one is taking this lightly. The TEPCO crews have continued to pump cooling water through the wrecked reactors to constantly cool the melted nuclear fuel. This cooling water picks up radiation in the form of radio nuclides. The water is then passes through a specialty filtering process to remove and capture much of the radiation, but the process does not effectively capture tritium because tritium forms water molecules and no filtration process in perfect. Tritium is a hydrogen atom that has two neutrons in the nucleus and one proton. Though produced naturally in the upper atmosphere, Tritium is also produced as a byproduct in nuclear reactors and nuclear explosions. Tritium has a 12 year half life and gives off only low-energy beta particles that are believed to pose limited risks for marine life and humans. However, there are limits to the ability of the Ocean to sustainability dilute the concentration of residual contamination. 

This project to release continues to move forward under the oversight of the IAEA and the Japanese Nuclear Regulatory Administration. Various groups are concerned that not enough testing has been done, and other radionuclides may also be passing through the filtration system. The Japanese fishing industry and other countries in the Asia-Pacific region have also expressed concern. You can review the Japanese NRA report and form your own opinion.

We are 12 years away from the Fukushima nuclear disaster and as nations look to decarbonize their electric grids nuclear is once more front and center in the discussion of how to provide carbon free base load to the power grid. Advanced Small Modular Reactors (SMRs) are a key part of the Department of Energy plans for the future of electric generation.