Under normal circumstances it can take up to 50 years before a nuclear power plant is fully decommissioned, but in the case of the Fukushima plant, it could take much longer. The next step of the process is the most dangerous so far – it involves removing uranium and plutonium fuel rods from a pool inside one of the reactor buildings. Tokyo Electric Power (TEPCO) is expected to start the job this month, and they can’t afford to take one wrong step.

Hiroshi Miyano, fuel assembly storage, Fukushima hydrogen explosion, uranium and plutonium fuel rod removal, Fukushima daiichi nuclear power plant, Tokyo Electric Power, nuclear decommissioning of Fukushima

The company has to remove more than 1,500 nuclear fuel assemblies or bundles of rods from a storage pool where they were being kept when a tsunami devastated Fukushima in March 2011. Even though the reactor these rods served was not in operation at the time, hydrogen from another reactor got into the building and exploded, tearing the roof off and leaving it at the mercy of earthquakes, storms or another tsunami.

A recently installed crane that uses a remote-controlled grabber will drudge through the pool to retrieve the fuel assemblies before it places them inside a fully-immersed cask. The 4.5-metre (15-foot) bundles, which weigh 300 kilogrammes (660 pounds) each, have to be kept in water throughout the operation to keep them from overheating. The process will then be reversed to place the 91-ton cask containing up to 22 fuel assemblies into a different pool.

This is the first practical milestone for the project,” said Hiroshi Miyano, a nuclear systems expert and visiting professor at Hosei University in Tokyo. “Any trouble in this operation will considerably affect the timetable for the entire project,” he said. “This is an operation TEPCO cannot afford to bungle.”

Even if engineers are successful, there still remains the much more complex task of removing misshapen cores from three reactors that went into meltdown. And they will mostly likely have to invent technology to do the job.

Via Phys.org

Images by Tokyo Electric Power