via Associated Press / November 19, 2013 / It’s costly, risky and dependent on technologies that have yet to be fully developed. A decades-long journey filled with unknowns lies ahead for Japan, which took a small step this week toward decommissioning its crippled Fukushima nuclear power plant.
Nobody knows exactly how much fuel melted after the March 2011 earthquake and tsunami knocked out cooling systems. Or where exactly the fuel went – how deep and in what form it is, somewhere at the bottom of reactor Units 1, 2 and 3.
The complexity and magnitude of decommissioning the Fukushima Dai-ichi plant is more challenging than Three Mile Island or Chernobyl, say experts such as Lake Barrett, a former U.S. regulator who directed the Three Mile Island cleanup and now is an outside adviser to Fukushima operator Tokyo Electric Power Co.
One core melted at Three Mile Island in 1979, versus three at Fukushima, and it didn’t leak out of the containment chamber, the outer vessel that houses the reactor core. At Fukushima, multiple hydrogen explosions caused extensive damage, blowing the roofs off three reactor buildings and spewing radiation over a wide area.
Chernobyl was a worse accident in terms of radiation emitted, but authorities chose an easier solution: entombing the facility in cement.
At Fukushima, TEPCO plans a multi-step process that is expected to take 40 years: Painstakingly removing the fuel rods in storage pools, finding and extracting the melted fuel within the broken reactors, demolishing the buildings and decontaminating the soil.
“This is a much more challenging job,” Barrett said during a recent visit to Japan. “Much more complex, more difficult to do.”
Also, water must continuously be channeled into the pools and reactor cores to keep the fuel cool. Tons of contaminated water leaks out of the reactors into their basements, some of it into the ground.
Uncertainty runs high as Japan has never decommissioned a full-size commercial reactor, even one that hasn’t had an accident. TEPCO has earmarked about 1 trillion yen ($10 billion) for the decommissioning, and says it will agree to Prime Minister Shinzo Abe’s request to set aside another 1 trillion yen to fight water leaks.