The operator of Japan’s crippled Fukushima Daiichi atomic plant plans to start cleaning underground tunnels believed to be part of the sources of radioactive materials poisoning the groundwater in the area.

The Tokyo Electric Power Company (TEPCO) will first block the flow of tainted water between the damaged buildings and the tunnels. Workers will begin burying pipes in the ground to carry refrigerants in January, NHK TV network reported. In April, they are set to start draining the contaminated water from the tunnels.



Late last month, TEPCO said it had found new leaks at the No. 1 reactor, in addition to the previous ones discovered last earlier in December. The latest incident on December 24 may have leaked around 225 tons of radioactive water, Japan Daily Press reported. It turned out that the water in that area contained Strontium-90, a radioactive isotope of strontium produced by nuclear fission with a half-life of 28.8 years, at a level as high as 440 becquerels per liter. The current temporary limit for water to be released from the concrete boundaries is said to be 10 becquerels of Strontium-90 per liter. A TEPCO representative feared the water may have already seeped into the ground.



On December 21, Tepco said it had found a record 1.9 million becquerels per liter of beta ray-emitting radioactive substances at its No.2 reactor, the highest since the nuclear meltdown in March 2011. The discovery was made after high levels of radioactive cesium were detected in deeper groundwater at the No. 4 reactor. Previously, the highest level recorded was 1.8 million becquerels at the No. 1 reactor on December 13. It's believed that the radioactivity in the groundwater at reactor No. 2 has been rising since November.



Since the outbreak of the Fukushima disaster in March 2011, leakage of radiation-contaminated water has been the major threat to Japan’s population and environment, as well as to the international community.



The chairwoman of the US Nuclear Regulatory Commission warned last month that water exposed to radiation from the wrecked plant would soon reach the US.



"The highest amount of radiation that will reach the US is of two orders of magnitude – 100 times – less than the drinking water standard," Allison Macfarlane told Bloomberg. "So, if you could drink the salt water, which you won’t be able to do, it’s still fairly low."



According to Ken Buesseler, a senior scientist at the Woods Hole Oceanographic Institution, radiation released during explosions at the plant meltdowns and during subsequent leaks of contaminated underground water will reach mainland US shores by early 2014.



The San Francisco Bay area city of Fairfax, California, passed a resolution in early December calling for more testing of coastal seafood and ways to reduce radiation emissions from Fukushima.

On December 4, the UN nuclear watchdog, the International Atomic Energy Agency (IAEA), advised the Fukushima Daiichi nuclear power plant to consider dumping toxic water into the ocean after lowering the level of radioactive materials to below the legal limit. Meanwhile, according to a draft report released by officials on the Japanese Industry Ministry's contaminated water panel, the Fukushima Daiichi plant could run out of storage space for contaminated water within two years. The report suggested covering the ground with asphalt to reduce the rain inflow and building giant tanks with more capacity, as well as installing special undersea filters to reduce the radioactivity of water that leaks into the sea. Currently, 400 metric tons of highly contaminated water is being produced at the site on a daily basis, much of it later flowing to the sea.



To tackle the problem, TEPCO has been running a test operation of an advanced water processing machine, known as ALPS, which can remove all radioactive materials except for tritium from tainted water. Its operation could be key to reducing the high levels of radiation in the water. TEPCO plans to clean up all of the tainted water through ALPS by the end of March 2015. It says that over 300,000 tons of radioactive water has been stored in 1,000 tanks at the Fukushima plant, and that the amount will double within a few years.



In July 2013 TEPCO acknowledged the fact that contaminated water has been escaping from basements and trenches of the Fukushima plant into the ocean. Since then, the operator reported two major leaks of highly radioactive water into the ocean from storage tanks – a 300-ton leak in August and 430 liters in October.



Major setbacks have stalled TEPCO's handling of the nuclear disaster amid widespread criticism and calls to put Fukushima-related work under government control. Earlier this week a former employee in the facility said that one of the reasons for so many leaks could be the cost-cutting measures applied by TEPCO, such as using duct tape and wire nets to mend the leaking tanks.