No, nothing did. There were no effects on human health or the environment. Instead, the accident achieved mythological status as a dreadful event, even though no one was hurt and deaths occur every year at all other types of power plants - except nuclear.
Four o’clock this morning, March 28th marked the 40th Anniversary of the partial meltdown of Reactor #2 at the Three Mile Island Nuclear Generating Station in Dauphin County near Harrisburg, Pennsylvania.
The accident involved a relatively minor malfunction in the secondary cooling circuit which caused the temperature in the primary coolant to rise. This in turn caused the reactor to shut down automatically. Shut down took about one second. At this point a relief valve failed to close, but 1970’s instrumentation did not reveal that fact, and so much of the primary coolant drained away that the residual decay heat in the reactor core was not removed.
The core suffered a partial meltdown as a result.
The operators were unable to diagnose or respond properly to the unplanned automatic shutdown of the reactor. Deficient control room instrumentation and inadequate emergency response training in the nascent industry proved to be root causes of the accident. This was quickly rectified at all reactors throughout the United States.
No health or environmental effects have ever been found to have occurred as a result of the TMI accident. More than a dozen major, independent studies have assessed the radiation releases and possible effects on the people and the environment around TMI since the 1979 accident.
The most exhaustive study was conducted in 2002 by the University of Pittsburgh’s School of Public Health. Their research tracked 32,135 people who lived within five miles of the plant when the accident occurred.
The researchers concluded, “This survey of data, which covers the normal latency period for most cancers, confirms our earlier analysis that radioactivity released during the nuclear accident at TMI does not appear to have caused an overall increase in cancer deaths among residents of that area over the follow-up period, 1979 to 1998.”
The Nuclear Regulatory Commission conducted detailed studies of the accident's radiological consequences, as did the Environmental Protection Agency, the Department of Health, Education and Welfare (now Health and Human Services), the Department of Energy, and the Commonwealth of Pennsylvania.
Several independent groups also conducted studies. The approximately 2 million people around TMI-2 during the accident are estimated to have received an average radiation dose of less than 1 mrem above the annual background dose of about 250 mrem, less than eating a bag of potato chips a day.
(Yes, potato chips are the most radioactive food because of the beta-emitting K-40 that is concentrated when you dry out the chip during cooking. However, like TMI, that’s still nothing to worry about)
On the other hand, the TMI accident was a cultural hallmark for the nation and a turning point for the industry. The NRC was strengthened and the industry established the Institute of Nuclear Power Operations (INPO) to ensure appropriate training, plant management and operations.
Things like stationing dedicated NRC inspectors at each plant, constant inspection of all safety systems and equipment, redundant back-up safety systems, constant interaction and sharing of lessons among every plant in America and the world, and many other upgrades and actions that have made nuclear first in safety and the U.S. first in the world. It has added a lot of cost, but safety is worth it.
It’s why we haven’t had any incidents since 1979 at TMI.
The rest of the world learned from us as well, although Japan and the Soviet Union decided to ignore some of it, which gave the world Chernobyl and Fukushima. But TMI put safety in the DNA of every American nuclear plant.
This is important. Nuclear turns out to be the safest form of energy there is. Period. By any measure - rate of human error, worker injury or death, equipment failure, effects on surrounding populations and the environment, number of unplanned shutdowns and level of occupational exposure.
Including all nuclear accidents in history, even wind and solar still kill more people per MWh of electricity produced than nuclear, although all non-fossil deaths involve accidents like falling off a ladder, roof or turbine. Hydro kills more than all other non-fossil systems. And fossil fuel kills way, way more than all the others combined.
The table above lists estimates of the mortality rate for each energy source as deaths per trillion kWhs generated over the last 40 years, plus an estimate of that source’s contribution to global and national energy use from the IEA. The numbers are a combination of direct deaths and epidemiological estimates and are an amalgam of many sources (1, 2, 3, 4, 5, 6, 7).
According to the World Health Organization, the Centers for Disease Control, the National Academy of Sciences and many health studies over the last decade, the adverse impacts on health become a significant effect only for fossil fuel and biofuel/biomass sources. In fact, the World Health Organization has called biomass burning a major global health issue (WHO).
Note that for coal, hydro and nuclear, the three sources where there are comparative numbers, the U.S. deaths are so much fewer than the global numbers. This is because of regulations and America’s general concern for workplace safety.
The Clean Air Act is why coal kills fewer people in America, the FERC is why hydro kills fewer people in America, and the NRC is why nuclear is so safe here in America. Some even point to TMI as the main reason for this, and how it made NRC stronger and made the nuclear industry even safer. Regulations are important and the NRC is the strongest regulatory agency in the world.
TMI #2’s sister reactor, TMI #1, kept running fine and has ever since. Exelon purchased TMI #1 in 2000, and since then has logged about 6 million safe worker hours, operated at over 90% capacity, and offset more than 95 million metric tons of carbon, equivalent to taking 20 million cars off the road.
So science fiction and Hollywood sensationalism aside, this anniversary should really be a celebration.
