Something similar may happen in Fukushima given the dispersal of radioactivity, including plutonium. Already, the Japanese government has declared the region within 20-kilometers of the stricken nuclear power plant a no-go zone, enforced by fines up to $1,200 and detention. And although such plutonium is not in itself soluble in water, it is clear from studies of heavily contaminated sites in Russia, such as former plutonium-making facility known as Mayak, that plutonium and other insoluble radioactive material tends to hitch a ride on tiny particles in the soil, known as colloids.
Other radioactive material, such as cesium 137 with a half-life of roughly 30 years, dissolves like salt in water, traveling into groundwater supplies and even plants. Uptake by plants is a real concern for any nuclear remediation, given the potential for human or animal consumption, although some fungi seem to thrive on radioactive material. "The trouble with particles with any living organism is breathing it, eating it, ingesting it, getting it into the skin," Kehler says. "A little bit of contamination can give a big dose because it's going to be there [inside] for a long time."
But there are other biological responses: Cooling water from TMI became a microbial farm—as is also likely to happen with the saltwater used in the emergency at Fukushima. "They started growing algae and bacteria in the reactor core," Akers recalls. "It's like a swimming pool that nobody's cleaning up."
What to do about the water?
Of course, dealing with contaminated water is a primary concern at any defunct reactor site and the primary response is filtration, such as with ion exchange columns that employ special resins to attract the radioactive elements and pull them out of the water, often employed in series. "The residual radioactive material itself [that is caught in those filters] is then solidified in some way suitable for low-level waste disposal," PNNL's Johnson explains. French nuclear giant Areva will employ such filtration techniques to help decontaminate radioactive seawater at Fukushima Daiichi.
In the case of TMI, after the water was filtered for heavier radioactive isotopes, it was left to cool so that light radioactive isotopes like tritium—an isotope of the hydrogen in water molecules—could break down. After 14 years, 8.7 million liters of it was simply allowed to evaporate. "They had the option of either dumping it in the [Susquehanna] River or evaporating it," Akers says. "They chose to evaporate it."
Tritium cannot be separated from water and has a half-life of more than 12 years, although it emits relatively little harmful radiation when it decays. TEPCO, in the case of Fukushima, will let some of the radioactive seawater sit on its site in massive storage containers.
At the same time, TEPCO has already dumped 11,500 metric tons of contaminated seawater into the ocean. That again will make radioactive material available to sea life, potentially ending up in fish or marine mammals that feed on them, based on previous such releases in the past. That may alter such animals' genetics as well as disrupt reproduction and development, although the exact effects remain unclear for lack of study.