But the Chernobyl catastrophe did not cause the kind of changes to the U.S. nuclear industry that followed the partial meltdown of the Three Mile Island plant near Middletown, Pa., in March 1979.
U.S. reactors have different plant designs, broader shutdown margins, containment structures and operational controls to protect against the lapses that led to the accident at Chernobyl, nuclear regulators say. They concluded that no immediate changes were needed in the design or operation of U.S. commercial nuclear reactors.
Daniel Sprau, a professor of environmental health at East Carolina University, is leading a group of six students to visit Chernobyl this week. Sprau said he is optimistic about nuclear power in the United States but wanted students to have a full perspective about its effects.
"I want them to see what happened in the past," Sprau said. "Although that reactor was totally different than any reactors we have in the U.S., I want them to see what could happen at its worst point. The lesson of Chernobyl is you have to keep up the safety."
Design flaws noted
The Chernobyl plant had no concrete containment dome over the reactor to prevent radiation from escaping, unlike Progress Energy's Shearon Harris Nuclear Plant southwest of Raleigh and other nuclear plants.
"That particular type of accident could not occur in the U.S. because of the design," said Joe Donahue, vice president of nuclear engineering and services for Progress Energy. "We have hardened containments that would keep an accident inside the boundaries."
The Three Mile Island plant had a containment structure that prevented the release of most of the radiation after the partial meltdown of the reactor core. Some radiation escaped through piping, but most was contained.
The accident, the most serious in the United States, brought changes in emergency-response planning and reactor-operator training and caused the U.S. Nuclear Regulatory Commission to tighten regulatory oversight.
In Wake County, critics say the Harris plant's four storage pools pose a threat of a catastrophic release of radiation if the pools caught fire or were breached in a terrorist attack. When spent fuel rods are removed from a reactor, they are highly radioactive and produce a lot of heat. The rods are submerged in water for years to cool.
Watchdogs cite pools
A report last year by the National Academy of Sciences said that terrorist attacks on spent fuel pools, while difficult, could result in the release of large amounts of radioactivity.
"The big parallel between Harris and Chernobyl is the amount of cesium," said Jim Warren, executive director of N.C. WARN, a Durham-based nuclear watchdog group. "Cesium is a radioactive material in fuel rods that caused the worst of the problems at Chernobyl. Those pools at Harris were calculated to contain 10 times as much cesium as was released at Chernobyl."
Warren said the key lesson is to minimize risk. That's why his group has urged Progress Energy to reduce the amount of fuel in the pools and relocate it to dry storage to reduce the likelihood of a fire.
Progress officials say the spent fuel at Harris is covered by 23 feet of water and protected by backup safety systems.
"I hate to say it would never happen," Donahue said. "The key is the design has to withstand unintended consequences."
