Workers were pumping rain water that was trapped in a concrete gutter into an empty 12-tonne tank that sat on open soil, said a spokesman for Tokyo Electric Power (TEPCO).
"Work crew started operating the pump around 10:38 am. At 11:50 am, they found water was spilling from the manhole on top of the tank," the spokesman said.
TEPCO has estimated roughly four tonnes of collected rain water might have escaped. The extent of contamination was unclear, the spokesman added, although it was not thought to be highly polluted.
TEPCO has long struggled to control waste water at the plant.
The company poured thousands of tonnes of water onto runaway reactors to keep them cool, and continues to douse them.
TEPCO has so far disclosed no clear plan for disposing of the huge amounts of stored polluted water, which is stored at hundreds of tanks at the plant.
Some tanks have leaked highly radioactive waste water, which might have washed to sea.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
