A trouble-prone system used to decontaminate radioactive water at the crippled Fukushima No. 1 nuclear power plant was switched off Sunday because of a chemical leak, Tokyo Electric Power Co. said.
Hydrochloric acid, used to neutralize alkaline water being decontaminated, was found seeping from a pipe joint, Tepco said in a statement.
The joint was wrapped in a vinyl bag to contain the leakage, Tepco said, adding it was investigating the cause of the trouble.
About 1 liter of hydrochloric acid has been contained in the bag.
The leak was found at one of three Advanced Liquid Processing System units designed to remove radioactivity from contaminated water at the plant, where a massive earthquake and tsunami in March 2011 sent nuclear reactors into meltdown.
The systems are expected to play a crucial role in treating huge amounts of toxic water accumulating at the plant.
The troubled system was one of two ALPS units that had been in trial operation and were scheduled to go into full operation Sunday.
In late September, plastic padding clogged up a drain in the same system, causing it to shut down. In October, it was halted due to a programming mistake.
Thousands of tons of water, used since the meltdown to cool reactors or polluted by other radioactive material, are being stored in huge tanks at the coastal complex.
A series of setbacks, including the flow of radioactive water into the Pacific Ocean, have eroded confidence that Asia’s largest utility can tame the world’s worst atomic disaster since Chernobyl.