(NaturalNews) A new leak at the crippled Fukushima Daiichi nuclear power plant in Japan must be repaired within about a week, or it could trigger another meltdown.
Three of the power plant's six reactors were offline when a massive earthquake and tsunami hit in March 2011. Damage sustained during the disasters caused the other three reactors to melt down. Even the three offline reactors, however, were still loaded with radioactive fuel rods that require constant cooling to prevent further meltdowns.
Temperatures rising steadily
Earlier this month, the news site RT reported that the Tokyo Electric Power Company (TEPCO) had been forced to shut off the cooling system at Fukushima Daiichi's Reactor Unit 5, which had not been damaged during the initial disaster. The shutdown was necessary because engineers discovered that Unit 5's cooling system was leaking radioactive water into the surrounding area. About 340 gallons of radioactive water had leaked before the system was turned off.
Radioactive water leaks have been a major problem for TEPCO's efforts to decommission the failed reactors. In addition to posing a serious safety risk to workers, water leaks have contaminated the groundwater beneath the plant, causing contamination to spread beyond the plant's boundaries and even into the Pacific Ocean.
The Unit 5 cooling system was turned off so that TEPCO can repair the leak, but that means that the fuel rods inside the reactor are now steadily rising in temperature, at a rate of about 0.193 degrees Fahrenheit per hour. At that rate, the rods will reach the temperature required for a runaway nuclear chain reaction (meltdown) within about a week. TEPCO has only that much time to repair the leak and start the cooling water flowing again.
The recent leak has been attributed to corrosion caused by the seawater that TEPCO has been using for emergency cooling needs. The plant's cooling system was designed for use with freshwater.
This is not the first case of seawater-induced corrosion; in November 2013, TEPCO discovered that the primary radioactive water containment vessel inside Reactor Unit 1 was leaking at a rate of 3.2 tons per hour. The leak was eventually traced to a joint in a pipe attached to the vessel and blamed on the use of seawater for cooling during TEPCO's initial reaction to the meltdown. Seawater has also been blamed for shortening the lifespan of sensitive equipment throughout the power plant.
The cooling systems have suffered other problems since 2011, including rats causing a blackout and an employee accidentally shutting the system down.
Cleanup beset with problems
Many of TEPCO's recent efforts at Fukushima have centered on attempts to limit the buildup of radioactive water. In addition to all the water made radioactive by continually keeping the plant's fuel rods cool, TEPCO must contend with groundwater that is leaking into the basement of the failed reactors, thereby also becoming radioactive. The company has been frantically pumping this water and storing it in giant, temporary tanks and has also recently begun injecting it into the Pacific Ocean, in spite of objections from local residents and fishermen.
TEPCO insists that radiation levels in this water are low enough that the practice is safe. The company's own tests, however, have repeatedly detected radiation levels in the water that surpass its safe exposure thresholds.
In order to slow the infiltration of groundwater into the plant, TEPCO has also begun construction on a giant network of pipes designed to freeze the ground around the plant into an "ice wall." However, even a small-scale pilot of the project has so far been unable to get cold enough for the ground to freeze.