The ice wall surrounding the damaged Fukushima Daiichi nuclear power plant, built to prevent radioactive-contaminated water from mixing with ground water, is now functional. The ice wall comprises 1,550 underground refrigeration pipes, and creates a 1.5-km barrier of frozen soil, AP reports.

The Fukushima plant was damaged dangerously during the 2011 tsunami, when the cores of the three reactors melted. The cores need to be constantly cooled. The water that is used as a coolant immediately becomes irradiated, and has to be treated and stored. However, some of the water is reported to have been leaking out of the damaged sections and mixing with groundwater. AP adds that the treated water has so far been stored in over 1,000 tanks around the plant, and warns of a real danger of the irradiated water leaking into the ocean.

The ice wall is meant to control the contamination through a network of pipes, which are reported to run 30 feet deep. The refrigerant pumped through them will freeze the earth to minus 30 degrees Celsius. The wall is reported to have cost 35 billion yen ($312 million) and was built by Kajima Corp. with government funding. The project was completed last month, after a delay of over a year.

The ice wall is not risk-proof either, notes AP. It may prove to be ineffective in the event of an emergency requiring a larger amount of water to be cooled. Also, the electricity costs involved to keep the wall functional will be excessive. However, the Tokyo Electric Power Co (TEPCO), the plant's operator, said once frozen, the wall can maintain temperatures for up to two months in the event of a power failure.

Meanwhile, the robots designed to navigate the nuclear power station and retrieve fuel roads have failed.