Containing a calamity creates another nuclear nightmare
Grim Task ... Japanese police, wearing protective clothing, carry a body recovered from the rubble in a rise paddy in the Fukushima Prefecture. Photo: AP
TOKYO: For nearly four weeks, Japanese emergency crews have been spraying water on the damaged Fukushima nuclear reactors in a desperate attempt to avert the calamity of a full meltdown.
The improvised solution to one nuclear nightmare is spawning another: what to do with the millions of litres of water that has become highly radioactive as it washes through the plant.
The water being used to try to cool the reactors and the dangerous spent fuel rods is leaking through fissures inside the plant, seeping through tunnels and passageways to the lowest levels, where it is accumulating into a sea of lethal waste. No one is sure how to get rid of it safely.
''There is nothing like this, on this scale, that we have ever attempted to do before,'' says Robert Alvarez, a former United States assistant secretary of Energy.
Japanese officials estimate about 57 million litres of highly radioactive water have accumulated and hundreds of thousands of litres are added daily as the operator, the Tokyo Electric Power Company, continues to feed coolant into the leaky structures.
Ultimately, the water will have to be stored and processed and the highly radioactive substances solidified, a job that experts say almost must be handled in a specially designed industrial complex. Cleaning the water could take many years, if not decades to complete. The cost could run into tens of billions of dollars.
The immediate problem facing the Japanese is how to store all that water until the reactors and the spent fuel pools are brought under control. The plant's main storage tanks are nearly full. To make space earlier this week, the company released 11.5 megalitres of the least contaminated water into the ocean, expecting that its radioactive elements will be diluted.
But international law forbids Japan from dumping contaminated water into the ocean if there are viable technical solutions available later.
So the plant operator is considering bringing in barges and tanks, including a so-called megafloat that can hold about 9.5 megalitres. Yet even using barges and tanks to handle the water temporarily creates a future problem of how to dispose of the contaminated vessels.
US and Japanese experts say the key to solving the disposal problem involves reducing the volume of water by concentrating the radioactive elements so they can be solidified into a safer, dry form. But waste experts disagree on exactly how to do that.
The difficulty of concentrating and then solidifying the contaminants depends on how much radioactivity is in the water, the type of isotopes in the water and whether the work can be done on site.
Edward Morse, a professor of nuclear engineering at the University of California, Berkeley, said the water needs to be diverted soon into a concrete-lined holding pond, where natural evaporation can help reduce its volume.
Even there, it could take up to 10 years before the radioactivity would decay enough for the material to be handled, he said. Building a storage pond ''buys you time''.
Other experts disagree, saying exposing the material to open air could allow iodine and other volatile substances to drift off the site, adding to the remote contamination that is already spreading dozens of kilometres from the plant.
Nuclear power plants normally have systems in place to treat tritium on site. But the condition and capacity of that at Fukushima are not known.
Professor Morse and Youichi Enokida, a nuclear chemist from Nagoya University, contend that if the water can be concentrated, it can then be rendered into a dry form or even turned into glass, as is planned at other contaminated sites around the world. This process, called vitrification, is expensive and requires a small scale industrial facility to accomplish.
The alternative - processing the waste elsewhere in Japan - is likely to be controversial. ''The fishermen will protest, this is inevitable,'' Professor Enokida said.
Professor Morse said there would be at least six months of emergency stabilisation, about two years of temporary remediation and up to 30 years of full-scale clean-up. Furthermore, the high levels of ground contamination at the site are raising concerns about the viability of individuals to work at the site in coming decades.
A workforce in the hundreds or even thousands would take years or decades to clean up, experts said.
Los Angeles Times