In March 2011, Japan experienced the largest earthquake in its history. A magnitude 9.0 earthquake shook the island and caused it to move nearly 15 ft. closer to the U.S. As the rumbling subsided, ocean waves 130 ft. tall crashed over protective sea walls and hammered the densely populated coast.
Four hundred and twenty miles of coast were affected by the events, with many roads and railways severely damaged. Over 500 thousand residential structures were annihilated leaving an estimated 300 thousand citizens without homes.
In its 78th year, the University of Tennessee's weekly science forum held at Thompson Boling Arena concluded the fall semester by welcoming Dr. Lawrence W. Townsend to give his analysis of the Fukushima Daiichi Power Plant disaster and its implications on U.S. nuclear energy.
Dr. Townsend is a tenured professor of nuclear engineering at the University of Tennessee. His areas of expertise include nuclear and radiological engineering, theoretical nuclear physics and shielding and risk assessment.
"The energy released in that (earthquake) was over the equivalent of 9 trillion tons of TNT." Townsend says.
He continued by noting the atomic bomb on Hiroshima emitted only about 15 thousand tons of force and it would take hundreds of thousands of nuclear bombs to equal the same amount of devastation.
The earthquakes knocked down power lines which caused the Fukushima plant to switch to emergency diesel generators and immediately initiate the shutdown process.
The Reactor Core Isolation Cooling System (RCIC) is responsible for cooling the reactor core and preventing nuclear meltdown. Essentially as cold water gets pumped towards the core, hydrogen rich steam is produced which must be vented away.
Less than an hour later, tsunamis destroyed the generators, leading to a total blackout of the station. With no power, the RCIC stopped, and the valves that release the hydrogenated steam return to the closed position.
As the water level inside the core went down, the temperature went up.
All the while unvented steam continued to build pressure and threatemed a breach in radioactive containment.
Japansese government officials ordered Fukushima operator Tokyo Electric Power Company to manually open the vents. This resulted in hydrogen within the steam to mix with oxygen from outside the plant, causing massive explosions that blew the roof off three of the four reactor buildings. The damage left nuclear fuel exposed and at the mercy of Mother Nature.
Although Japan had only planned for a magnitude 8.0 earthquake and a 19 ft. tsunami, they were still well prepared. Townsend says that the major difference between Fukushima and Chernobyl is that the Japanese reacted quickly and evacuated everyone within 18 miles of the plant.
In comparison, the amount of radioactive material released in Fukushima was only about 10 percent of that in Chernobyl. Of the 195 thousand people that were removed, only about 100 of them showed signs of contamination.
According to the most recent data from the Red Cross, 16,000 deaths have been confirmed, 90 percent of which were caused by drowning. An estimated 4,000 people are still missing as a result.
Nearly eight months later, Townsend reports that reactor units 1, 2 and 3 are currently in the process of cooling down. A roof has been replaced on one of the buildings and work to replace the other two is ongoing.
Homes and schools are the number one priority for the cleanup efforts. Current estimations of recuperative efforts exceed $300 billion USD.
Townsend pointed to several opinion polls that showed a 50 to 60 percent approval rating for nuclear energy. Countries like Italy and Germany are moving towards fossil fuels while other countries like France, Russia and China have plans to continue pursuing nuclear technology.
Regardless of opinion, the event caused many countries--including the US--to reconsider their policies on nuclear energy. The U.S. Nuclear Regulatory Commission formed a task force to make recommendations for nuclear energy in the 21st century.
The task force so far has made upgrade recommendations like a more advanced ventilation system, a mechanism that can cover exposed fuel cells and an extended timeline for out-of-power situations.
Here in Tennessee, the Tennessee Valley Authority has already implemented several policies that specifically deal with failures like Fukushima experienced.
Townsend finished by saying, "Nuclear power still remains a safe necessary and vital part of the energy mix in the U.S. and will remain so for the foreseeable future."