Ray Rothrock

Fukushima Daiichi – “A successful failure”

In Energy on March 26, 2011 at 8:34 am

As a former nuclear engineer from the 1970s my friends think I’m still an expert on nuclear power.  So I’ve been studying all the news and reading up on the technical elements about the Fukushima Daiichi nuclear reactor problems resulting from the horrific earthquake and tsunami.  Of course, this is a most tragic situation for the people of Japan with over 10,000 people dead and close to 20,000 still missing from the earthquake and tsunami.  And it is complicated with the problems at the Daiichi nuclear plants.

As the data on the nuclear events (www.nei.ord) comes in and the engineers at Tokyo Electric continue to manage the cooling issues they face, it becomes very clear to me that the engineers at these plants and the plants themselves have performed amazingly well.  Yes, AMAZINGLY WELL.  In the aftermath, while things have not gone as expected in some cases, the Japanese have managed it all extraordinarily well given the potential lethal radioactivity contained in a power plant core.  The six plants maintained well their cores even when some were destroyed within with only minor leakage of radioactivity.  It is only a matter of time and hard work and the plants will be completely in a cold shutdown state.  It is my understanding that many of the Japanese workers have made extraordinary sacrifices in their line of duty to bring the situation under control.

The plants performed as expected given the historical earthquake and oversized tsunami.  Unfortunately, when the station blackout occurred approximately 9 hours after the plants were scrammed, there was not adequate cooling to handle the decay heat, a natural consequence of uranium fission.  Though safety systems did engage as designed, they simply ran out of fuel or battery capacity to keep up.  Normally, the most critical time upon shutdown of a nuclear fission plant is the first 24 hours.  Decay heat drops from about 6% of plant energy level to less than 0.5% during this period.  Clearly, if the plants had had 24 hours of battery backup rather than 8 hours to keep the cooling systems running after the diesels lost fuel as a result of the tsunami, the situation now would be very different and perhaps the damage even minor.  Lesson learned.

I read from NEI that the design tsunami for this location was 4.4 meters, about 14.5 feet of water.  The tsunami that hit the plant on March 11 was 14 meters.  That’s 46 feet or a full 31 feet over the wall.  Imagine that, 31 feet of water travelling at a very high rate of speed and smashing into everything and wiping out all in its path including the diesel fuel tanks and power infrastructure so important for those first 24 important hours.

These events in no way reinforce the argument against nuclear energy as an unreliable or unsafe source of electricity for the world.  Despite it all, the plants survived better than expected.  These plants survived an unimaginable natural event.  And even with this event in Japan, the track record of the nuclear industry is remarkable and unassailable.  It’s amazing to me how when a nuclear thing goes wrong, suddenly the critics say, “see, I told you so!”  Nonsense.  These plants of the 1960s vintage performed remarkably well in light of what they faced.  It is a testimony to human ingenuity and good engineering that these survived as they have.  The Japanese engineers continue to manage the situation well and I am totally confident the plants will all come to cold shutdown in due course.  As President Nixon said of the Apollo 13 astronauts when they safely returned to Earth, “It was a successful failure.”  As so is this experience with the Fukushima Daiichi nuclear station.  Just as Apollo program continued with several more trips to the moon, so should the world press on with development of nuclear energy.

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