Specialised robots that have been created to retrieve radioactive material from Japan’s ill-fated Fukushima power plant have been unable to complete their task because the radiation destroys their circuitry when they get close.
The decommissioning of the Fukushima reactors has been plagued by a string of radioactive water errors since an earthquake and tsunami hit the plant in 2011.
In May last year the UN’s nuclear watchdog criticised the way in which the radioactive waste and contaminated water had been handled since the 2011 incident.
The current level of radiation at the plant is still so powerful it has proved impossible to get into its bowels to find and remove the extremely dangerous blobs of melted fuel rods.
The fuel rods melted through their containment vessels in the reactors, and their exact location is unknown.
This part of the plant is so dangerous to humans, that Tepco, the plant’s operator, has been developing robots, which can swim under water and negotiate obstacles in damaged tunnels and piping to search for the melted fuel rods.
But according to Naohiro Masuda, Tepco's head of decommissioning, as soon as the robots get close to the reactors, the radiation destroys their wiring and renders them useless, causing long delays.
Each robot has to be custom-built for each building, a process that takes roughly two years.
In addition, a subterranean ‘ice wall’ around the crippled plant that is meant to stop groundwater from becoming contaminated has yet to be finished and authorities are struggling with increasing amounts of highly radioactive water that is stored in a growing number of tanks around the site.
A major part of the decommissioning process involves pumping a steady torrent of water into the wrecked and highly radiated reactors to cool them down. Afterward, the radiated water is then pumped out of the plant and stored in tanks that are proliferating around the site
Akira Ono, who is managing the site, has admitted he is ‘deeply worried’ that the storage tanks will leak radioactive water into the sea, which has happened in the past, prompting strong criticism for the government.
Ono estimates that Tepco has only completed around 10 per cent of the work to clear the site up and the full decommissioning process could take up to 40 years. But until the company locates the fuel, it won't be able to assess progress and final costs, experts say.
The underground ice wall in construction is currently the world’s largest and Tepco plans to pump water into the wall later this year to start the freezing process.
"The reactors continue to bleed radiation into the ground water and thence into the Pacific Ocean," said Arnie Gunderson, a former nuclear engineer. "When Tepco finally stops the groundwater, that will be the end of the beginning."
While he would not rule out the possibility that small amounts of radiation are reaching the ocean, Masuda, the head of decommissioning, said the leaks have ended after the company built a wall along the shoreline near the reactors whose depth goes to below the seabed.
"I am not about to say that it is absolutely zero, but because of this wall the amount of release has dramatically dropped," he said.
Nearly 19,000 people were killed or left missing and 160,000 lost their homes and livelihoods after the tidal wave hit Fukushima almost five years ago to the day.
Scientists from the University of Barcelona have been investigating the levels of radioactive strontium and cesium in the coast off Japan and found that radioactive levels in seawater were 10 to 100 times higher than before the nuclear accident, particularly near the facility, suggesting that water containing strontium and cesium isotopes was still leaking into the Pacific Ocean.
A Japanese court also recently ruled that another Japanese nuclear power plant, Takahama, would need to halt its operations at two nuclear reactors at its plant, disrupting Prime Minister Shinzo Abe's efforts to restore atomic power to the country.
This is the first injunction issued in Japan to halt a nuclear plant that is under operation. Kansai Electric, the company that runs the plant, said it would not accept the verdict and would quickly appeal the injunction, but it could mean months or possibly a year of delays and extra costs for oil, gas or coal to replace the nuclear generation.