Three Mile Island — Thirty Years Later

Thirty years ago this week, the Three Mile Island accident shook the nuclear industry to its core. A meltdown – the thing that all the experts insisted couldn’t happen – happened. Hollywood, which had just released “The China Syndrome” starring Jane Fonda, had done a better job of predicting the future than had the computer projections of fault-tree mathematicians.

What can we say today about Three Mile Island and its aftermath? I would say three things:

1)The accident, if nothing else, proved that the consequences of a nuclear accident were not as serious as imagined.
2)The culture surrounding nuclear power, rather than the technology, led to the events.
3)The industry has learned its lesson and improved operating and safety procedures almost beyond recognition. Such an accident is not likely to happen again.

The Consequences of an accident:
The general public has always thought of a nuclear reactor as a domesticated bomb that could explode in a mushroom cloud at any minute. Sophisticated critics knew a reactor can’t blow up, but they imagined a similar situation where an overheated core melted through the reactor vessel, through the containment structure and “all the way to China.” Supposedly it would hit groundwater at warp speed and cause a steam explosion that would (as the movie said) “render an area the size of Pennsylvania uninhabitable.” (Give them credit for choosing the right state.)

None of this happened. The overheated core didn’t even melt through the chromium lining at the bottom of the reactor. Three Mile Island was a serious industrial accident that caused a billion dollars worth of damage and almost bankrupted the utility. What was unusual about it is that no one was hurt.

Chernobyl, on the other hand, which followed seven years later, was a Soviet specialty. Using a graphite moderator, the Soviets effectively packed the fuel rods in charcoal. When the core overheated, it ignited the carbon, which burned for days, sending a plume of radioactive smoke all over the world. Oh yes, they also neglected to cover it with a containment structure. All Russians reactors now have containments (although a few still use graphite moderators). Such an accident will never occur again in a country not run by infallible Marxist ideologues.

The Culture, not the technology, was at fault
In a brilliant 1980 article in Reason (“Who Caused Three Mile Island?”), Adam Reed pointed out that thirty years of secrecy at the old Atomic Energy Commission had cut off nuclear power from all the advances in industrial psychology following World War II, particularly the realization that human factors were usually the main cause of accidents:

By 1970 no new design for a toaster or blender at General Electric could get off the drawing board without being examined by an expert in human factors. Yet the same company was designing, manufacturing, and delivering nuclear reactors that had never been seen, much less examined by an engineering psychologist. . . . It was only after the loss of the Three Mile Island plant in 1979 that engineering psychologists asked what the hell was going on in nuclear power plant control rooms. What they saw made them shiver.

While industrial psychology had emphasized “user friendly” aspects in equipment, nuclear control panels consisted of rows and rows of identical lights and switches with no differentiation as to what was important and what was not. As Samuel Walker later wrote in his history of Three Mile Island:

Within a few seconds after the accident began, the plant’s alarm systems, including a loud horn and more than a hundred flashing lights on the control panels, announced the loss of feed-water in the secondary loop, the turbine trip, the reactor trip, and other abnormal events. But they offered little guidance about the cause of those occurrences and did not differentiate between trivial and vital problems.

Each reactor was an island unto itself, with few common designs or procedures and little communication. The valve that failed at Three Mile Island had failed nine times previously, yet nobody had done a thing about it. The operators at the plant spent four hours a year discussing what was happening at other reactors.

The Kemeny Commission, which performed a brilliant investigation of the accident, concluded: “[G]iven all the above deficiencies, we are convinced that an accident like Three Mile Island was eventually inevitable.”

The industry has reformed itself
Working on the recommendations of the Kemeny Commission – and the draconian oversight of the Nuclear Regulatory Commission – the industry has made spectacular improvements in both operations and safety. Whereas early reactors were often manned by high school graduates, licensed operators now go through a five-year regimen, undergoing more training than airline pilots.

Control panels have been completely redesigned, computerized (the switch from analog to digital made a big difference), and completely duplicated in pitch-perfect simulators, where they spend one week in six honing their skills. With oversight from the Institute for Nuclear Power Operations (INPO), the industry now communicates almost instantaneously on safety matters.

The result has been a spectacular improvement in both operations and safety. Whereas capacity factors hovered around 60 percent until 1990, the entire industry now operates above 90 percent. While there were 22 year-long shutdowns for safety problems from 1976 to 1986 and 23 from 1986 to 1996, there has been only one in the last decade.

The record for continuous operation – 688 days, six weeks short of two years – is now held by Unit 1, Three Mile Island.

William Tucker has written about environmental and energy issues for twenty-five years. His work has appeared in Harper’s, The Atlantic, National Review, New Republic, The New York Times, The Wall Street Journal, and many other publications. His most recent book Terrestrial Energy (Bartleby) is about nuclear power. He is a regular guest contributor to The Infrastructurist.