Wednesday, August 23, 2023

Fukushima Begins Releasing the Stored Water


water tanks at TEPCO Fukushima Plant

The Tokyo Electric Power Company (TEPCO) and the Japanese government announced on Tuesday that the operation to release the filtered and stored groundwater at the Fukushima nuclear plant would begin on Thursday and it did. (Today already happened in Japan.)

After staging a successful test on Tuesday, taking a sample of about 1 cubic meter of treated water and diluting it with about 1,200 cubic meters of seawater. The treated and diluted water was then tested to verify the treated water had been diluted as expected. The tritium concentration were measured to confirm that it is less than 1,500 becquerels per liter.

Now TEPCO will begin diluting large amounts of treated water from storage tanks and  releasing the diluted treated water into the ocean. The Japanese National Federation of Fisheries Cooperative Associations has continued to oppose the water release plan concerned about the impact the reputation of seafood from Fukushima and nearby areas. It was reported that despite all the preparation and investigation China issued a partial import ban on Japanese seafood by Hong Kong and Macau.

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 the groundwater 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 is 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.

TEPCO will gradually release up to 22 trillion becquerels of tritium per year from the Fukushima Nuclear Power Station over the next 20 or 30 years. The level of tritium in the water that will be released from the Fukushima Nuclear Power Station is below the maximum amount of tritium in drinking water recommended by the World Health Organization (10,000 becquerel per liter).  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. Tritium levels will be monitored and reported on the TEPCO website.

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