Tokyo Electric Power Co. plans to start removing nuclear fuel from the spent-fuel pool at the top of the reactor 4 building at the crippled Fukushima No. 1 plant as early as Nov. 8, about a week earlier than scheduled, sources close to Tepco said Wednesday.

The process, to continue until the end of next year, will mark a new stage in the decommissioning of the reactors 1 to 4, which were severely damaged in the nuclear crisis triggered by the March 11, 2011, mega-quake and tsunami.

Reactor 4 unit was the only one of the four not to experience a meltdown because its fuel had been in the spent-fuel pool during maintenance work. But there is concern over the continued storage of the more than 1,000 fuel assemblies in the pool, which is located inside a reactor building that suffered a hydrogen explosion.

Tepco had planned to begin the process from mid-November, but it has nearly completed preparations, including the installation of a crane to remove the fuel.

If the safety of the equipment is confirmed by the Nuclear Regulation Authority, Tepco will start taking out the fuel.

The fuel will be placed in containers and taken to what has been called a common pool in a different building about 100 meters away that is expected to provide more stable conditions for keeping the fuel cool.

The reactor 4 spent-fuel tank currently contains 1,331 spent fuel assemblies and 202 unused ones. Tepco succeeded in taking out two unused fuel assemblies in a trial last year.

The challenging task will be carried out along with the ongoing fight to contain the spillage of massive amounts of highly radioactive water accumulating at the plant as a result of continuing water injections into the crippled reactors 1, 2 and 3.

Tepco said Wednesday that it detected 59,000 becquerels per liter of beta radiation, emitted by radioactive substances including strontium, in water taken from a drainage channel near a storage tank that was found to have leaked 300 tons of highly toxic water in August.

The water sample, extracted the previous day, showed a record-high figure. To prevent the radioactive water inside the channel from flowing into the Pacific, Tepco has placed sandbags at a downstream section.