I feel the earth move under my feet
I feel the sky tumblin’ down
Carole King – 1971
Another week off of my planned strategic overview. The twin events of an earthquake near North Anna nuclear power plant in Virginia and Hurricane Irene sweeping up the coast has brought a lot of FUD (Fear Uncertainty and Doubt) articles about nuclear power. Because I live in Wilmington, NC and been through a number of hurricanes (including direct “in the eye” experience) AND I lived in San Jose, CA for the 1989 Loma Prieta earthquake, I feel that I might offer some perspective and potential clarity.
Since the earthquake occurred first, let’s tackle this one. First, nuclear power plants are not designed to “Richter Scale” criteria. The Richter Scale is used to roughly measure the energy released in the earthquake. It doesn’t consider distance from the epicenter, how deep the earthquake was, or how the energy released might travel through the earth. What really matters at a nuclear facility (or any OTHER facility for that matter) is the actual ground motion at the facility. The direction and harmonic frequency of the waves and how they might cause equipment to shake, rattle, and roll also play a factor. However, the general public knows Richter Scale, so in an effort to be helpful nuclear plants have sometimes converted the criteria into a rough equivalent of the Richter Scale.
This conversion, however, is cause for confusion and unnecessary FUD. The translation is usually meant to imply the earthquake was located on a fault directly below the facility. In reality being even a few hundred feet off that line makes a significant different in the amount of motion. So a 6.0 earthquake under the facility might provide one level of ground motion, but the same earthquake 100 yards away would be a lower ground motion at the facility.
Picture a rock thrown into a still pond. The rings of ripples spread out from the rock as they get larger in diameter, they get smaller in size until they disappear. Earthquakes are much the same. What matters for a building or facility is that ground motion.
Similarly, for hurricanes, the facilities are designed for a specific wind speed and expected storm surge (if they are on the coast). Facilities located even a few miles inland do not have potential storm surge issues, but are designed for possible flood scenarios. A category 3 hurricane (like Irene) headed toward North Carolina, does not mean that Brunswick Nuclear power plant will experience category 3 winds The category is designated by the maximum sustained winds measured in the storm, these winds are usually at or very near the center of the storm. In addition, the presence of land significantly slows the winds at ground level. So, once again, proximity to the storm and the coast matters.
In the case of hurricanes, there is yet another significant bit of knowledge, with today’s radars, satellites, and radios, we know about hurricanes many days before they make landfall. This allows the utility to prepare in advance. The NRC requires these plants to shut down if hurricane force winds are expected within a few hours. The plants are well aware of the risk to offsite power and are careful to assure themselves that the EDGs will start-up when needed.
A final word about natural disasters – I’ve seen many people ask questions about why nuclear power plants are not designed for “the ultimate natural disaster”. It is a good question. I like to explain it along these lines. All facilities, including nuclear power plants, oil refineries, and natural gas facilities, are designed to withstand events that are likely to take place during the facilities expected lifetime. The designers look at natural phenomena that occur in the region proposed for the facility, evaluate the likelihood of occurrence during the plant lifetime, the impact on the facility, the resulting impact on the surrounding population, and determine to the best of their ability the best cost vs. risk balance. In the nuclear industry, the NRC has to review and approve all of those decisions before the reactor can be built. In addition, unlike many facilities, these “design basis accidents” are re-examined when significant new information comes in. Plants are upgraded as required to assure continued safety.
Arguing that the facility should be designed to withstand the “ultimate natural disaster” is like arguing that cars should be designed to assure no one will ever die in a car crash. There are vehicles that survive crashes at 200 mph and allow the driver to walk away, they cost millions of dollars and are usually driven on race courses. If we demanded that automobiles protected the passengers such that no one ever died in a car accident, these would be the only cars on the road and very few people would drive.
In addition, how should one determine “the ultimate”? Is that a magnitude 10 earthquake directly under the facility? could a bigger quake happen? Same thing with hurricanes and floods. What is “the ultimate”? What is going to prevent something bigger? Should every facility plan for a direct hit from an asteriod as well? Determining how to draw the limit line isn’t easy, it requires turning human life into a number and weighing those numbers against each other. This calculus is done all the time from our court settlements, to insurance policies, to safety features on vehicles, to industrial facility design. Singling out a single technology and demanding that human life in regards to that technology is somehow more valuable is misguided and will result in more dangerous technologies and more deaths.
In the past 12 months in the US, no nuclear power plant killed a single person. They all behaved exactly as designed, shutting down when hazardous events occurred and providing electricity to hundreds of thousands of people and industries. About 37,000 people died in car crashes. About the same died from the use of coal in the US. So where should we be placing our concern regarding risk?