Since Fukushima plant is so close to the sea and its basement is leaking, and since the amount of processed nuclear waste stocked there is already not manageable without any visibility on a future solution, it is quite a possibility that most of the “decontaminated water” just flows into the Ocean. Indeed, if, as TEPCO stated, 500,000 liters of “groundwater” leaked in the plant everyday, there is little doubt that this “groundwater” leaks back out into the Ocean, after being contaminated to some extent (after all, the plant is not flooded).
According to Mainichi Shimbun mainstream newspaper :
Professor Akio Koyama at Kyoto University Research Reactor Institute says, “The density of high-level decontaminated water is believed to be a maximum 10 billion becquerels per liter, but if it is condensed to polluted sludge and zeolites, its density sometimes increases by 10,000 times. The density cannot be dealt with through conventional systems.” [End of Mainichi Shimbun quote]
This leads us to the following back-of-the-envelope computation :
10 billion Becquerels per litter x 500,000 liters per day x 200 days = 1,000,000,000,000,000,000 Becquerels or 1000 peta-Becquerels
This is already much higher than the 15 peta-Becquerels reported by TEPCO for March only. Even if we considered their figure over 6.5 months, it would still be 10 times less than the result above. TEPCO unethical methods have largely been documented enough to consider this as a serious possibility.
Besides, Kyodo news agency reported that :
Researchers at the Meteorological Research Institute and the Central Research Institute of Electric Power Industry estimated that the amount of radioactive cesium-137 that was directly released into the sea came to 3,500 terabecquerels from March to the end of May, while estimating that roughly 10,000 terabecquerels fell into the ocean after it was released into the air. [End of Kyodo quote]
10,000 tera-Becquerels is the same as 10 peta-Becquerels. We know that Fukushima continues to diffuse radioactivity in the atmosphere so 6.5 months later, this amount of atmospheric Ocean contamination could be linearly extrapolated to 25 peta-Becquerels.
So we can add this atmospheric ocean pollution to our hypothetical direct flow computed above and reach the figure of 1025 peta-Becquerels – or roughly 1 exa-Becquerels – or, if you prefer, a quintillion Becquerels (the atmospheric radioactive source being a minor contributor in the end).
At this rate of 2 exa-Becquerels per year dumped into the Ocean, it would take 500 years to reach the next prefix, i.e. zetta-Becquerels, which is out of our life timeframe. Hence, I think that the new unit for nuclear disasters should be the exa-Becquerel – and we maybe just have reached it for the Pacific Ocean.
The Mainichi Shimbun article with Pr. Koyama’s quote is reproduced below :
Radioactive waste piles up at Fukushima nuclear plant as disposal method remains in limbo
Three months after the start of full-scale water circulation system operations at the crippled Fukushima No. 1 Nuclear Power Plant, high-level radioactive waste has kept piling up amid no clear indications of its final disposal destination.
As of Sept. 27, plant operator Tokyo Electric Power Co. (TEPCO) had accumulated about 4,700 drums of radioactive waste after three months of cesium decontamination operations initially using U.S. and French equipment which was later joined by Toshiba Corp.’s “Sally” system in August.
Since the start of October, TEPCO has conducted the plant’s water circulation operations using the Sally system alone while relegating its U.S. and French counterparts built by Kurion Inc. and Areva SA, respectively, to backups.
The Kurion and Sally systems are designed to purify decontaminated water through an absorption unit called a “vessel” that contains zeolites. The vessel is changed every few days and the used vessels become radioactive waste.
Areva’s water treatment system filters contaminated water by having sand absorb radioactive materials and precipitate with the help of chemicals. But the treatment produces highly polluted sludge.
According to TEPCO, radioactive waste as of Sept. 27 included 210 Kurion-made vessels (a total of about 307 cubic meters) with each vessel measuring 0.9 meters in diameter and 2.3 meters in height and 581 cubic meters of sludge via the Areva unit.
The radioactive waste has been kept at a temporary storage site on the premises of the Fukushima plant, which was heavily damaged by the March 11 earthquake and tsunami, and subsequent hydrogen explosions and meltdowns. But TEPCO has been unable to fully grasp the details such as the types and the concentration of nuclear materials.
Professor Akio Koyama at Kyoto University Research Reactor Institute says, “The density of high-level decontaminated water is believed to be a maximum 10 billion becquerels per liter, but if it is condensed to polluted sludge and zeolites, its density sometimes increases by 10,000 times. The density cannot be dealt with through conventional systems.”