Fukushima nuclear cleanup remains plagued by complexities

Japan on Monday marked the anniversary of the March 2011 earthquake and tsunami that destroyed three of the six reactors at the Fukushima Daiichi nuclear power plant.

Shortly after the magnitude-9 earthquake struck on March 11, a series of tsunamis inundated four of the reactor buildings and set off a chain reaction in three reactors that resulted in the release of significant amounts of radioactivity into the environment.

Tens of thousands of locals were quickly evacuated and, over the following years, the reactors were stabilized.

The challenge in recent years has been to gather the large amounts of nuclear fuel that escaped from the reactors in order to halt the release of more radiation — something that had never been attempted before and has to be carried out in buildings where radioactive contamination remains dangerously elevated and where debris from the tsunami and subsequent hydrogen explosions still litters the area.

Tokyo Electric Power Co (TEPCO), the operator of the plant, has estimated that work to make the plant safe will take between 30 and 40 years, but recent reports on progress at the site have been largely negative.

TEPCO delays test work

In January, TEPCO announced that it would have to delay plans to commence in March the test use of a robotic arm to remove radioactive material from the No. 2 reactor. The initial plan called for tests using the robotic limb to take place in 2021 but were delayed by technical glitches.

TEPCO is now aiming to have the remote-controlled arm operational in October, although that will be three years behind the original schedule.

Other areas of the project have also experienced challenges, with the first drones and a robot sent into the No. 1 reactor building earlier this month also suffering faults. The drones and robot had to be withdrawn before they could complete their mission to locate molten fuel debris that has leaked from the reactor and to map other damage.

TEPCO, however, maintains that steady progress is being made and that the 30- to 40-year target for decommissioning remains viable.

"We are moving safely and steadily forward with each task needed to achieve the main goal" of the decommissioning roadmap, the company said in a statement to DW.

"Based on the roadmap and the Nuclear Regulation Authority's 'Risk Map,' the decommissioning steps to be taken over the next 10 years have been compiled in the mid-and-long term decommissioning action plan, which is periodically revised in light of decommissioning progress and the emergence of new issues that need to be addressed," TEPCO said.

The company is also keen to point out its achievements, including the complete removal of spent nuclear fuel from units three and four at the site, a sharp reduction in the amount of water seeping into the chambers beneath the reactors and becoming contaminated with radiation as well as the successful treatment of radioactive water below according to standards set by the International Atomic Energy Agency (IAEA) before it is released into the Pacific Ocean.

Vincent Gorgues, the chief of staff to the French High Commissioner for Nuclear Energy and presently one of three international special advisors to Japan's Nuclear Damage Compensation and Decommissioning Facilitation Corp, told DW that progress to date has been overwhelmingly positive, despite the countless challenges.

"Nuclear projects are complex," he said. "Among them, decommissioning projects are highly singular and offer a higher level of difficulty, due mainly to the level of uncertainty about the initial state of the facility and to difficulties in managing safely all the radioactive waste streams."

The complexity is multiplied at the Fukushima site, he said.

Even access to site 'very difficult'

"Even today, access to the reactor buildings is very difficult and requires fully remotely operated means of intervention, while carrying out investigations and having a precise idea of what needs to be done, even before considering how to do it, is a huge challenge in itself," Gorgues said.

In addition, each of the three crippled reactors has its own set of specific challenges and there is no disposal site for the highly radioactive nuclear waste that must be recovered from the site, he pointed out.

The key steps now are to remove all the spent nuclear fuel, whether intact or leaked, from inside reactor buildings one and two, and the retrieval and disposal of fuel debris from the partial core meltdowns.

Gorgues said he favors speeding up the release of treated water from the plant in order to dismantle the hundreds of storage tanks that presently occupy much of the site, with that land needed for new waste treatment and storage facilities.

The expert also played down suggestions that TEPCO would likely not be able to stick to its declared timeline for the decommissioning process, emphasizing that the three- or four-decade schedule is "a target" rather than a deadline.

'Not a race but a careful approach'

"This is not a race, but a structured, careful, stepwise approach, which at every stage requires you to take time, determine the best strategy and guarantee both short-term and long-term safety," Gorgues said, adding that the radiological conditions "are extremely hostile."

"This indicative timeframe of 30 to 40 years had two communication goals: to show that it would take a long time; but also to show that the timeframe would remain commensurable with one professional career and that the burden would not be passed on over several generations. It is in that spirit that we must consider this target."

He added that given the unique challenges presented at Fukushima, it was always going to be inevitable that the schedule of operation would have to evolve.

"I would like to stress, however, that these delays have remained minor and that most of what was announced has been achieved," he said. "In my opinion, and under these conditions, what has already been done is a remarkable achievement."

Edited by: Srinivas Mazumdaru