The operator of the damaged Fukushima Daiichi nuclear power plant will build additional tanks on the site to store 100,000 tons of radioactive water.
Tokyo Electric Power Company revealed its revised storage plan at a meeting with government officials on Monday.
TEPCO had planned to build tanks to store a total of 830,000 tons of water by the end of fiscal 2014, which ends on March 31st next year.
Now the firm says additional storage should be ready in case the planned tanks are not enough to store all tainted water at the site.
It says the capacity may be exceeded if preventative measures, including frozen underground walls, do not work as well as planned.
Senior vice industry minister Kazuyoshi Akaba chaired Monday's meeting. He said the risk of radioactive water overflow can be avoided if the tanks are built on schedule.
He added his ministry will work to develop technology to decontaminate water.
Jul. 14, 2014 - Updated 20:46 UTC