The operator of Japan’s damaged Fukushima nuclear center has begun testing a process to release treated wastewater into the sea. Tests began Monday as workers examined processing equipment at the newly-completed seaside pumping center, said Tokyo Electric Power Company Holdings (TEPCO). The water release is necessary to move forward with cleanup efforts at the Fukushima center. Three reactors there suffered meltdowns after a 2011 earthquake and huge ocean waves destroyed the plant’s cooling systems. The disaster forced 160,000 people to flee nearby areas poisoned by radioactive material. The water has already gone through a process designed to remove harmful materials. This is why the government describes it as “treated” and not “radioactive.” But experts say it is impossible to remove all the radioactivity. TEPCO and government officials say tritium a radioactive form of hydrogen is the only substance that cannot be removed from the water. They say tritium is not considered harmful in small amounts. Equipment will first mix the treated water with large amounts of seawater. The mixture will then enter an undersea passage, called a tunnel, to be released into the Pacific Ocean about 1 kilometer from the coast. The testing by TEPCO is expected to last about two weeks. After that, the pumping operation will need to be examined by the country’s Nuclear Regulation Authority. Those required tests are likely to begin in early July.