Lessons from Fukushima
Hindsight is always 20-20. And the past cannot be changed. What is tragic is not learning from past mistakes. And the Fukushima nuclear accident provides ample material to learn from.
The Fukushima plant was built to withstand a large earthquake, and Indeed it appears that the plant came thru the massive 3/11 quake relatively in tact. And its systems acted as they should. The plant began a shutdown of its reactors. The main power lines that provided electricity to the plant were badly damaged, but again the back up generators kicked in and provided the necessary electricity for the plant to continue the shutdown process.
That is when the tsunami hit. There was a 6 meter high sea wall built to protect the plant. The massive tsunami easily flowed over the seawall, flooded the plant and knocked out the back up generators. The plant had taken great precautions against possible earthquakes, but had woefully inadequate protection from tsunamis. In fact Tepco (Tokyo Electric Power Company) had ignored all warnings about the dire consequences if a tsunami were to hit the plant.
Lesson one: Scenarios that appear highly unlikely do occur. Mother nature is a force of great power and unpredictability. Man builds an “unsinkable” boat, the Titanic and it sinks on its maiden voyage. Our lack of preparedness is often due to our lack of imagination.
With the back up generators knocked out, the cooling system critical for preventing a meltdown no longer worked. Workers at the plant in desperation used car batteries in order to try and get some of the plants’ systems back online. Tepco headquarters in Tokyo received requests for all kinds of supplies for Fukushima as the crisis began to unfold, but when batteries to supply power to the plant were delivered by the Japanese Self Defense Forces, they were 2 volt batteries, not the 12 volt batteries the plant required. Sadly as three of the reactors experienced meltdown, 1000 12 volt batteries sat in storage a mere 55 km away.
Lesson two: After you’ve prepared for the worse, and disaster strikes, what is your plan to deal with disaster. Tepco seems to have had no plan on what materials would be crucial in a crisis and how they could be quickly delivered in an emergency. Since Tepco couldn’t imagine a situation where both their main power and their back up system failed, there was no planning on what could be done to provide power to the plant in such an event. Again the lack of belief in worse case scenarios, led to lack of preparation when they occurred.
The reactors were equipped with safety relief valves to vent steam if the pressure in a reactor got too high. These valves were very difficult to open without electricity. The workers were finally driven to venting off some of the contents of the reactors in a desperate move to avoid a full meltdown. However, some of the piping used in the process may have been damaged in the quake, as the venting didn’t work properly. The reactor’s containment chambers were built to withstand a large earthquake, but the piping was built to a lower standard.
Lesson three: The containment chamber is usually given the most attention in regards to safety, but the systems that are used to regulate its pressure and maintain its integrity must also be built to high standards.
The tragedy of Fukushima is that it was avoidable. It was the lack of imagination and preparation for what are extremely low probability events that led to the disaster. The higher the cost of failure, the more necessary it is to prepare for low probability events. Reactors are in use for decades, and over longer periods of time, improbable events can and do occur.
Many of the reactors online throughout the world are decades old. How prepared are they for these kinds of worst case scenarios? Or will we find out their unpreparedness only after the next disaster?