On December 5, 2011, new contaminated-water leaks from the earthquake and tsunami-damaged Fukushima Nuclear Site were reported by its operator, Tokyo Electric Power Company (TEPCO). The water leaks occurred in a recently constructed facility designed to purify contaminated water being used to cool the nuclear fuel in the site’s damaged reactors.
Fukushima Purification System
On June 27, shortly after the accident at Fukushima, TEPCO placed a purification system designed to decontaminate and recycle the cooling water through Fukushima’s damaged reactors into operation. Engineers hoped for a stable state, a necessary and critical role for a cold shutdown, by the end of the year. In the purification system, radioactive water is pumped through four devices: a oil separator, a cesium absorption filter, a decontamination unit, and a desalinization unit. The purified water is then recycled through the reactors for further cooling, and then sent back to the purification system again, for further treatment. After the accident, it became necessary to build the purification system quickly, as the need for clean water grew critical, and radioactive water accumulated on the site. Due to the hasty construction of the purification facility, many expressed fears that it could be vulnerable to subsequent leaks, earthquakes, or typhoons. A new system was installed in September, 2011.
The Fukushima Leak
TEPCO announced today that the purification system has developed a problem, wherein 45 tons of water (11,700 gallons) leaked from the system, most of which was contained in a concrete casement. Although they report that the leak is stopped, an estimated 80 gallons, or 300 liters, found its way through a crack in the concrete casement, into a gutter drain that runs directly to the Pacific Ocean. The leak is significantly smaller than the original amount of radioactive water dumped in April, which was about 11,500 tons. All remaining water has been pumped from the building where the leak occurred. TEPCO is still evaluating how much contaminated water may have reached the ocean but has stated that it will continuously conduct sampling surveys as it awaits the results.
Radioactive Water: Health Risks
TEPCO said the water had one million times more than the maximum safe level of strontium-90 set by the government. Radioactive cesium appears to have already been removed from the water prior to the leak. Stronium-90 poses a potential health risk, as it is produced through nuclear fission and can be found in waste from nuclear reactors. Stronium-90 emits a beta particle, and has a half-life of 29 years. Strontium-90 is absorbed through dust, eating, and inhaling. Approximately 80% passes through the body, while 20-30% can be absorbed into the bones and teeth, where it may remain, providing a source for bone cancer.
Dangers of Ocean Contamination
If the TEPCO estimates are accurate, the amount of contaminated water reaching the ocean from the reported leak is minor compared to the amount of contaminated water released to the ocean in the months following the accident. Therefore, this new leak would not constitute an egregious additional health risk. Although the exact numbers are still pending, the ocean is large and could minimize any potential risk through dilution. The issue from this spill suggests the latest question: is TEPCO in control, and can they bring the damaged plants to a state of cold shutdown by the end of the year as projected?
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