Hexbyte – Tech News – Ars Technica |
The meltdown of the reactors at Fukushima Daichi has changed how many people view the risks of nuclear power, causing countries around the world to revise their plans for further construction and revisit the safety regulations for existing plants. The disaster also gave the world a first-hand view of the challenges of managing accidents in the absence of a functional infrastructure and the costs when those accidents occur in a densely populated, fully developed nation.
Earlier this week, New York’s Japan Society hosted a man with a unique perspective on all of this. Naomi Hirose was an executive at Tokyo Electric Power Company (TEPCO) when the meltdown occurred, and he became its CEO while he was struggling to get the recovery under control. Ars attended Hirose’s presentation and had the opportunity to interview him. Because the two discussions partly overlapped, we’ll include information from both below.
Hexbyte – Tech News – Ars Technica | The accident and safety
During his presentation, Hirose noted that the epicenter of 2011’s Tōhoku earthquake was only 180 kilometers from Fukushima. But initially, safety protocols kicked in; called a scram, the protocols led to control rods being inserted into the reactors to shut down the nuclear reactions and bring the plant to a halt. Since this had happened previously in response to earthquakes, Hirose said people were feeling confident the situation was under control.
But the earthquake itself had damaged the power lines that fed the plant, leaving it reliant on internal power to run the cooling pumps. And the source of that power was swept away when the tsunami generated by the quake inundated all six of the reactors on the site. This left the plant unable to cool its reactors; several melted down, and the hydrogen they generated ultimately led to explosions that wrecked the buildings that housed them. Hirose suggests that these explosions were likely sparked as things shifted and fell due to aftershocks.
This has led countries around the world to tighten their rules regarding backup equipment and to re-evaluate the infrastructure they assumed would be available to help manage the accident. We also got a chance to ask Hirose about how he viewed the risks of nuclear power after this experience:
We learned that safety culture is very important. We saw that we were probably a little arrogant. We spent a huge amount of money to improve the safety of that plant before the accident. We thought that this was enough. We learned that you never think this is enough. We have to learn many things from all over the world. 9/11 could be some lessons for nuclear power stations—it’s not just nuclear accidents in other countries, everything could be a lesson.
So we learn: “Do not stop improving the safety.” This is a technical matter, a scientific matter, and we can make these risks as small as possible.
Hexbyte – Tech News – Ars Technica | Re-establishing control
In the immediate aftermath of the accident, what had gone wrong in some of the reactors wasn’t even clear; contaminated groundwater was a massive issue, and a substantial exclusion zone forced the evacuation of thousands of residents nearby. Just to do anything on the site required huge amounts of safety gear.
“[In the] first several years, we didn’t have a really clear plan, because it’s troubleshooting,” Hirose told Ars. “Many, many things took place, so we had to settle down these things. Now the condition of the plant is very stable.”
With the stability, one of the first steps chosen was to remove spent fuel, which was stored in elevated tanks in the reactor buildings. Reactor four shut down when the earthquake struck, and more than 1,500 fuel rods have since been safely removed. At reactor three, rubble covering the spent fuel pool has been cleared, and a new roof incorporating a crane has been built, paving the way to remove the spent fuel there.
But the melted-down reactors pose a much larger challenge. “We don’t know exactly the condition of the debris, so we developed several different types of robotics and le