Workers at the Fukushima Daiichi nuclear plant fixed a leak Wednesday that was allowing radioactive water to spill into the sea, officials from the Tokyo Electric Power Co. said.

The apparent breakthrough capped a five-day struggle to plug a concrete pit with an eight-inch crack. Engineers had tried to fill the crack with concrete and polymer but were unsuccessful, and water — with a dosage rate several times the amount that nuclear plant workers can be exposed to in a year — continued to flow into the Pacific.

This time, Tepco said, the crack was treated with a sodium silicate. Tepco said it will check the disaster-stricken facility for additional cracks.

It remained to be seen whether the repair of the crack would improve radiation levels in the nearby water, particularly given that workers have been dumping 11,500 tons of radioactive water into the sea. The five-day dumping operation is part of Tepco’s plan to remove low-level radioactive water from the site and create more storage room for radioactive water that has accumulated in the plant.

The contaminated water has raised concerns about the possibility of radioactive elements entering the food chain.