TOKYO, Sept 28 (Reuters) - All three damaged reactors at Japan's crippled Fukushima Daiichi nuclear power plant are below the boiling point, paving the way to bring them to a state of cold shutdown by the end of the year, the operator of the complex said on Wednesday.
After a devastating earthquake and tsunami in March knocked out cooling systems and caused meltdowns of nuclear fuel rods at three of the plant's six reactors, Tokyo Electric Power (Tepco) has been trying to cool them and bring temperatures below the boiling point.
Temperatures at two of the three reactors had already dropped below 100 degrees Celsius in July and early September, leaving just one reactor above boiling point.
But temperatures at the last of the three reactors fell to 99.4 degrees on Wednesday, according to Tepco spokesman Takeo Iwamoto.
"The temperature has been moving up and down but it is on a steady decline," Iwamoto told Reuters. "We have cleared the temperature issue and taken a step forward towards achieving cold shutdown by the end of this year."
Technically, a cold shutdown occurs when water used to cool nuclear fuel rods remains steadily below 100 degrees, preventing the fuel from reheating.
But Tepco has said it won't declare a cold shutdown until other criteria are met, like further reducing the amount of radiation being emitted from the plant.
Last week the Japanese government and Tepco said at a monthly review of the Daiichi plant's cleanup timetable that they are now aiming to bring the plants to a cold shutdown within this year, instead of by January as initially planned, with their cleanup work proceeding steadily.
Achieving a cold shutdown is a precondition for the return of residents who were forced to evacuate areas near the plant.
(Reporting by Tetsushi Kajimoto; Editing by Ed Lane)