By Meredith Angwin
I have been in the nuclear industry most of my life. Yet when I watched the unfolding situation at the Fukushima Daiichi reactors in Japan, I had the same questions as anyone else: How did this happen? Could it happen in this country?
One should never say “this cannot happen here”, but two major factors mean that a Japanese-type accident is extremely unlikely to happen here. The first is the type of disaster that started the accident, and the second is how the American plants have been modified.
The Japanese accident started with an earthquake and tsunami of immense proportions. The combination killed 25,000 people, swept houses and trains out to sea, and destroyed immense amounts of infrastructure such as roads and power lines. The tsunami destroyed the plants’ backup power generators. Without power, the plants could not pump coolant water through the reactor cores (which were shut down but still hot) and the spent fuel storage pools.
Comparing the destruction caused by the tsunami to conditions that can occur in the Eastern United States is not reasonable. New England gets hurricanes and floods. Nuclear plants have survived numerous hurricanes and floods, including Hurricane Katrina. A forty-foot tsunami is something completely different.
Vermont Yankee has the same boiling water reactor model as the Fukushima plants. However, just like an older subdivision where the houses have been modified and no longer look alike, the plants in Japan and those in the United States have experienced different operating histories and different sets of safety improvements. Specifically, the U.S. plants went through three rounds of safety improvements that the Japanese plants did not address.
1) Hydrogen gas control. After the Three Mile Island accident in 1979, U.S. plants installed special sturdy piping (“hardened vents”) to prevent hydrogen from accumulating within the reactor building. Information is incomplete at this time, but it appears that most Japanese plants did not add such vents.
2) Better Risk Assessment. In the 1980s the American nuclear industry started to use a new way of assessing risk, Probabilistic Risk Assessment. Each U.S. plant did a PRA, and these assessments increased the number of possible scenarios that the plants had to prepare to handle. The new assessments required that all plants (including Vermont Yankee) had to be prepared for a 500-year flood. The Japanese plants were woefully underprepared for a 500 year tsunami.
3) Security Upgrades to Backup Generators. After 9/11, the U.S. plants launched a third round of “security upgrades”. The plant managers will not tell you exactly what they did, but some changes were obvious. Plants must show they are prepared for lengthy electric system blackouts, when both the grid and onsite diesel generators are not available. Our plants have hookups for auxiliary generators that could be brought in by the Army. In Japan, attaching mobile auxiliary generators to the core coolant pumps was difficult and time-consuming.
Are American nuclear plants safe enough? Clearly, after Fukushima, every nuclear plant in the world will have to review its back-up power supplies, its spent fuel storage pool management, and many other aspects of emergency planning. The NRC has already ordered this review for American plants.
We don’t ground all airplanes when a plane crashes. We don’t shut down all refineries when a refinery burns. We don’t shut down all natural gas pipelines when one suffers an explosion. Our local geography (not subject to tsunamis) and our plant safety improvements mean that it’s highly likely that New England nuclear plants will continue to run safely for many years to come.
No nuclear accident in a power plant in the United States has ever hurt anyone outside of the plant. The U.S. nuclear power industry also has an excellent safety record for the people working within the plant.
America obtains 20% of its electricity from nuclear power, and Vermont Yankee provides a third of the electricity used in Vermont. Our plants are safe, and we need to keep them running.
Meredith Angwin is the director of the Ethan Allen Institute Energy Education Project. She was a project manager at the Electric Power Research Institute, first in the renewable energy group and later in the nuclear group. She has a master’s degree in physical chemistry and is an inventor with several patents to her credit.