Taking on Fukushima

02 May 2014

One month after being put in charge of decommissioning Fukushima Daiichi, Naohiro Masuda talked to World Nuclear News about his priorities for the site and its workforce.

Masuda, May 2014 250x227
Naohiro Masuda

Masuda was superintendent of the Fukushima Daini nuclear power plant at the time of the Great East Japan Earthquake and tsunami. Under plant blackout conditions Masuda and his staff systematically repaired equipment to safely bring all four reactors to cold shutdown. Tepco has acknowledged that his 'decisive actions' in the crisis 'were credited with avoiding an accident' - under Masuda's leadership the entire Daini staff worked to restore grid power by laying an 8.8 kilometre heavy-duty cable by hand in a single day.

Now appointed head of the Fukushima Daiichi Decontamination and Decommissioning Company, Masuda is equally direct in setting his priorities: "Our promise to the prime minister of Japan is that we should reduce the risk this financial year [ending March 2015]. My target is that point."

This means eliminating leaks from the tanks holding water that has been contaminated by being used to cool the reactor remains, and getting better performance from the decontamination systems. Some 480,000 cubic metres of this water must be processed by the deadline. Uncontrolled contamination of groundwater also remains a problem and a water bypass needs to be set up, while research continues on the best ways to freeze the ground and prevent groundwater being contaminated.

Masuda said, "In the first place, I put my effort on improving site conditions so that the site would not cause any threat to society even if something unexpected happens." In parallel, he must guide Fukushima Daiichi and its staff through a transition for long-term cleanup. The staff need to update their mindset from operation of a clean power plant to decommissioning of a highly complex site.

"We must emphasise safety culture in everything we do, both to protect the workers and to remove distractions from their ability to safely perform the complex task at hand."

"We should become conscious that the status is very different," he said. Tepco had long experience of operating a fleet of 17 reactors, so a task like transferring some water, for example, "is easy - because we have manuals and numbered valves and we can easily follow the procedure. And if anything goes wrong - a defect or a rupture - the facility maintains integrity because we have a containment dam to stop release to the environment and we have alarms etc. We have good reliability."

"In normal operation we can understand the equipment and the relative importance of each part. But now, the facility is dramatically changed. We use a temporary tank and plastic piping for transfer of much higher contaminated water and in case of a rupture the water could reach the environment immediately."

The components that form the backbone of nuclear safety in an operating power plant - for example the primary circuit pumps or the reactor pressure vessel - are now irrelevant. "The temporary tank is the important thing now, but the mindset has not yet changed. I tell them every day!"

The second part of Masuda's transition should take the site from "fire-fighting" mode to a steady mode for the long term. "In three years our staff has made a big effort and improved the facilities to stabilise the plant. I appreciate and respect that very much. Now we should change the mindset to one of a stable state. We will use these facilities for the next 30-40 years and set up good procedures and manuals for that timescale. At present we have a risk of leaks to sea and we should protect against those and improve reliability."

The Fukushima 5000

Supporting the Daiichi staff is important to Masuda. He is establishing a nine-storey building where some 1200 workers can rest at once, and he wants to reduce the use of full-face masks where he can. These masks have a range of effects: they are used to reduce internal radiation dose, but they slow down work hugely and lead to problems with communication and the quality of work done. Properly zoning the use of masks is Masuda's top priority to improve conditions for staff. He will also increase Tepco's oversight of contractors and change the scope of workers' contracts to longer terms of two to three years, giving them more job security and giving him flexibility to combine higher- and lower-dose work. "We must emphasise safety culture in everything we do," he said, "both to protect the workers and to remove distractions from their ability to safely perform the complex task at hand."

The new arrangement, where Masuda's decommissioning company is a subsidiary of Tepco and separate from its power generation business, means that "organisational responsibilities and objectives are now very clearly defined." He is pleased that he can "work more closely with local communities and make decisions faster."

"I thank Hamadori [the coastal portion of Fukushima prefecture] for my personal growth as well as my growth as an engineer with Tepco. I deeply regret and feel sorry for forcing people in the region to evacuate their hometowns. I am going to communicate with them in an understandable manner, based on what local communities would like to know." 

By Jeremy Gordon
for World Nuclear News