Fukushima: Radioactive Water Leaking From Containment Tanks


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Why is there still a leak at fukushima? Image by Shigeru23

Radiation-contaminated water is flowing from Japan’s Fukushima-Daiichi nuclear site into the ocean.

What does that mean?

How is the water being contaminated, and where is the water coming from?

Finally, what is the plan to control the flow of contaminated water and prevent it from getting to the ocean.

Let’s  take a look at the Fukushima reactor’s current situation.

Fukushima Leak: Where is the Water coming From?

The Fukushima site was hit by a 9.0 earthquake and resulting tsunami on March, 2011. TEPCO, the country’s largest utility, is still dealing with the stabilization and decommissioning of the three reactors with core meltdown. Presently, they are pumping large amounts of water through the cores to reduce the high heat still being generated.

The large quantities of water they use to cool the core becomes highly contaminated with radionuclides from the core materials. This water is stored in the 1000 tanks standing on the grounds of the site. At first, the water was cleaned – but the task became so large that they had to deal with the storage issue at a later time, and improvised approximately 350 of the tanks by bolting together steel plates with plastic packing materials to seal the seams. This makes these tanks vulnerable to potential leaks.

Leakage has occurred in these tanks before, but the recent Fukushima leaks went undetected by plant workers for as long as a month; and leaked nearly 72,000 gallons or 300 tons into the ground which found its way ultimately to the ocean. Since the workers discovered the latest leak, they’ve removed the water from the leaky tank, and begun removing contaminated soil around the tank. This probably won’t be the last leak to occur.

The large amount of groundwater flowing through the reactor building complex that mixes with some of the contaminated core water and flows into the ocean presents a challenge to TEPCO.

The Fukushima nuclear site is located on a slope where the groundwater running down from the Abukuma plateau flows. Approximately 300 tons of ground water run through the plant site every single day. The sheer volume of water makes the contamination at Fukushima a logistical nightmare to control.

Fukushima Daiichi Leak: A Level 3 Incident

The International Nuclear and Radiological Event Scale is a worldwide tool that communicates the severity of a nuclear or radiological accident to the public. Events are ranked on a scale of 0 to 7. Both the Chernobyl and Fukushima accidents were ranked a 7, a major accident with widespread health and environmental effects. The leak described above was ranked a 3, a serious incident, the highest ranking since the Fukushima earthquake and tsunami event. A Level 3 is non-lethal deterministic health effect from radiation for people and the environment.

What is in Fukushima’s Contaminated Water?

The main actors are strontium-90 and cesium-137. Strontium-90 is produced through nuclear fission, we find it in waste from nuclear reactors. Strontium-90 emits a beta particle and has a half-life of 29 years. Much like calcium, it can concentrate in our bones and teeth. Strontium- 90 gets into people through dust, eating and inhaling. Approximately 80% passes through the body while 20-30% can be absorbed into the bone where it may stay, providing a source for bone cancer.

Cesium-137 has a half-life of 30 years and produces a beta particle. Cesium is particularly dangerous because it acts like potassium; it is taken up by the body and hangs out in muscle. Cs- 137 travels easily in the environment and is very difficult to clean up.

Aluminum, and many other materials, stops beta decay energy but once ingested, both cesium-137 and strontium-90 can do significant damage and add to potential cancer cases.

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