nuclear-news

Nuclear fuel removal is small step in cleanup at Fukushima  http://www.asahi.com/ajw/articles/AJ201904190031.htmlApril 19, 2019  Tokyo Electric Power Co., the operator of the crippled Fukushima No. 1 nuclear power plant, has started removing radioactive fuel rods from the fuel storage pool for one of the three reactors that melted down in the 2011 nuclear disaster.Massive amounts of melted nuclear fuel debris remain in the cores or containment vessels of the No. 1 to No. 3 reactors, which melted down. In addition, many fuel rods, batched into assemblies, are stored in storage pools within the reactor buildings.

These pools could be seriously damaged if the plant is hit by another big earthquake or tsunami. Moving spent fuel from these pools to the safe common pool within the premises is an important step to preventing accidents and ensuring steady progress in the process of decommissioning the reactors.

All the 1,535 nuclear fuel assemblies that were in the No. 4 reactor building, which did not melt down because it was shut down at the time of the accident, were removed by the end of 2014. Since workers could enter the building, the operation was conducted in a normal manner.

By contrast, areas around the fuel storage pool for the No. 3 reactor remain inaccessible due to high levels of radiation. The situation requires the removal operation to be remotely conducted from a control room about 500 meters from the No. 3 reactor building.

The work involves putting nuclear fuel assemblies into special containers under water and lifting them up with a crane and putting them down onto the ground for transportation to the common pool. This is a tricky and risky mission that has to be carried out with great care and caution by using a monitor.

Initially, the process of removing the fuel rods from the storage pool for the No. 3 reactor was scheduled to start at the end of 2014. But it has been repeatedly postponed due to technical mishaps and other reasons. It was finally started after a delay of more than four years.

The plant operator, known as TEPCO, plans to relocate all 566 nuclear fuel assemblies that have been kept in the storage pool in the No. 3 reactor building by the end of March 2021.

To reduce the risks posed to the process by possible earthquakes and tsunami, it is desirable to carry out the work quickly. But making undue haste could cause problems and accidents that disrupt the process. Meeting the schedule should not be the top priority.

Experience and expertise to be accumulated through the work with the No. 3 reactor will come in handy for the same fuel removal work with the Nos. 1 and 2 reactors, which could be initiated as early as in fiscal 2023, which starts in April 2023.

The other two reactors, however, will pose even tougher challenges. The debris situation of the No. 1 reactor building is worse, while radiation levels within the No. 2 reactor building are higher.

It is vital to obtain sufficient experience and know-how through the process of removing fuel rods from the No. 3 reactor.

TEPCO needs to ensure steady progress in the process through effective and close information sharing with related manufacturers and other actors involved.

No decision has yet been made as to what to do with the spent fuel after being transferred to the common pool. This is a complicated and knotty issue that does not lend itself to an easy, quick solution, just like the problem of a rapidly increasing amount of radiation-contaminated water the plant is generating as the reactors are being flooded to cool the melted fuel debris and underground water keeps flowing in the reactor buildings.

In 2021, the utility plans to launch the even more challenging mission of removing melted fuel debris from one of the three reactors.

Prime Minister Shinzo Abe recently visited the Fukushima No. 1 nuclear plant for the first time in five years and promised the government’s committed leadership for the efforts to decommission the reactors and deal with polluted water.

The Abe administration should provide really strong and effective leadership for the long, grueling process in line with the prime minister’s pledge.

Both the government and TEPCO have a duty to move the decommissioning process steadily forward while winning support from the local communities through sincere and serious dialogue.