Tokyo Electric Power (Tepco), operator of the crippled Fukushima Daiichi NPP, is optimistic of a breakthrough in the clean-up of the plant after new images showed possible melted uranium fuel rods in pictures taken underneath the damaged unit 2 reactor. Photographs and video footage from a remote-controlled camera show black lumps on wire-mesh grating under the reactor's pressure vessel. These were not present before the earthquake and tsunami destroyed the NPP in 2011 causing a tripple meltdown.

If confirmed, this could pave the way for Tepco to remove the melted fuel after years of delays, missteps and leaks of radioactive water. Previous attempts to use robots to locate melted nuclear fuel failed because the devices were rendered useless by the strength of the radiation. Tepco technicians located the black lumps using a remotely controlled camera attached to the end of a 10.5-metre-long telescopic arm, local media reported. Tepco plans to send a scorpion-like robot equipped with cameras, radiation measuring equipment and a temperature gauge into the No 2 reactor containment vessel next month, according to the Asahi Shimbun.

Developing technology to remove the fuel should become easier once Tepco can gauge its condition. While this is a step forward, clean-up at Fukushima remains a huge and complex task. Japanese media said earlier in January that plans to remove used fuel from the unit 3 reactor building had been delayed, while decommissioning the entire plant was expected to take at least 40 years.

In December, the government said the estimated cost of decommissioning the plant and decontaminating the surrounding area, as well as paying compensation and storing radioactive waste, had risen to JPY21,500bn ($187bn), nearly double the estimate released in 2013.