When the first atomic bombs were dropped on Hiroshima and Nagasaki, the world witnessed the birth of weapons of mass destruction and a powerful new source of energy. Minor mistakes or carelessness with such incredible power would have a very deadly and costly outcome, such as the case with the Three Miles Island nuclear power plant.
The plans of constructing the first nuclear reactor were approved in 1966 with the second reactor approved two years later, in 1968; Three Miles Island itself is a small island located in the Susquehanna river, by Harrisburg, Pennsylvania. Before the plant was built the island was mostly used for farming, and the surrounding community was mostly geared towards farming.
There were several advantages the area provided, the factories close by needed a large amount of energy that the plant would be able to provide, the nearby Susquehanna river could provide the coolant needed for the continued operation of the plant, and the opening of the plant would also provide jobs for the local area, which the region desperately needed after the Olmstead air force base closed down in 1964.
The reactors did not begin commercial operation until 1974, when TMI-1 became operational, four years later, in 1978, the second reactor TMI-2 would become operational. The 70s were a time where there was much optimism of nuclear energy meeting the needs of a growing nation, during this time the construction of nuclear power plants in America was high.
This attitude, however, quickly diminished once the events in the nuclear power plant unfolded, public backlash and government involvement encouraged nuclear experts to change their safety procedures and designs after the Three Miles Island accident. Nuclear power plants were designed with the idea that each safety measure would be different from one another, as to not cause conflict in another area if on area fails due to mechanical problems, electrical problems, or human error, but despite the intricate safety measures in place, an unfortunate event still occurred.
On March 28, 1979, at 4:00 a.m, the maintenance activities of the TMI-2 reactor caused the secondary loop pump to shut down, this allowed heat to buildup in the primary loop, in response to this the reactor automatically shut down, now there was significant pressure in the primary loop pump, the pressurizer detected this and a relief valve opened letting the radioactive water escape to a drain tank underneath the reactor.
The pressure would return to normal shortly after, the operator would then send a signal from the control room to the valve to close it, an electrical signal was then sent back to the operator showing that the relief valve did close, however, it did not show the exact position of the valve, which was slightly cracked open. Another sensor displayed information that there was high pressure in the drain tank which means there was a leak, the indicator, however, was located high up on a 7-foot instrument panel.
The control room was, shortly after, bombarded with warnings from several different systems, operators were confused and had a hard time knowing the right course of action to take as a result. When the auxiliary building tanks overflowed, the radioactive water spilled onto the basement floor, a radioactive gas “xenon” escaped through the building’s ventilation system into the local community.
The remaining water in the primary loop pump started to boil, the steam from the boiling caused the large primary cooling pumps to vibrate violently, they were shut down to avoid equipment damage. One hundred minutes into the event the core temperature started to rise due to the core not having enough cooling water covering it since all of it escaped through the opened pressurizer valve. Large amounts of hydrogen started to build up within the containment building because steam was reacting with the cladding material of the fuel rods, which was zirconium alloy.
The Nuclear Regulatory Commission (NRC) was worried that the hydrogen might explode, this was later determined that it was impossible because of the lack of oxygen. With the core melting, overheating and fuel rod cladding chemically reacting, core strength started degrading, 50 percent of the core was melted by molten fuel which is
created from fuel elements melting within the reactor vessel. The reactor vessel never ruptured because there was still enough cooling water to prevent the molten fuel from causing a nuclear meltdown. Almost all the radioactivity was kept in the containment building, very little escaped the accident.
After the accident, the first study on the Three Mile Island accident was done by the Kemeny Commission, which was chaired by John G. Kemeny a Hungarian-Austrian mathematician and president of Dartmouth College at the time. They reconstructed the events that transpired in the power plant that day and what they found was interesting.
They found that at the time TMI-2 reactors water purifier was replaced during regular maintenance. This lead to air and purified water to enter into the reactor, due to mechanical failures and operator error the plant monitoring system could not display this information correctly and alert the operator of the foreign substance. After the study was concluded,
the Kemeny commission blamed the nuclear industry for being too complacent about their nuclear safety regulations, they said that the government response was not satisfactory, they also stated stated operators needed better training to respond to complex conflicts.
On march 30th governor of Pennsylvania, Dick Thornburgh, ordered pregnant women and children to evacuate from a five mile radius of the plant. 150 children and pregnant women have been sent to a shelter in Hershey, more than 10 miles away from the power plant. As for the other portion of the populous no evacuation was necessary, Thornburghs original orders were to stay inside. Businesses and schools were closed, mass-care centers were established in the chance a meltdown would occur.
On April 8th, in Harrisburg 1,000 people gathered for a anti-nuclear protest and demanded Three Mile Island to permanently stop its operations and shut down. The protesters also stated that the public utilities agency had refused to increase power rates by 20 or more percent to the Metropolitan Edison Company, who are the owners of the Three Mile Island nuclear power plant. Dr.Thomas Winters is an associate professor in medicine from the University of Massachusetts Medical School, he told the protesters that officials were not completely honest with the amount of radiation leaked from the reactor.
In addition to this protest, on the second anniversary of the accident in 1981 on March 28th, another protest happened at Harrisburg this one was much larger at a stagering 10,000 protesters and was sponsored by the Labor Committee for Safe Energy and Full Employment. This group of protesters called the shutdown for nuclear power plants, and wanted to guarantee union jobs for nuclear workers at union pay.
On June 5th, Babcock and Wilcox, the company responsible for building the Three Mile Island nuclear reactor, stated that they are not at fault for what happened at Three Miles Island, instead they blamed the company that operated the plant, the Metropolitan Edison Company, and their workers. Babcock and Wilcox were, however, not innocent as they admitted to knowing about a faulty valve. On July 18 Babcock and Wilcox engineers testified to
the presidential commission, both Mr.Dunn and Mr.Joseph J. Kelly told the commission members that they have been trying to contact Babcock and Wilcox officials about future concerns a year before the accident took place, but were unable to get a response, this testimony from the engineers showed that the company was careless in addressing concerns from professionals and destroyed their innocence claim.
The costs of the Three Miles Island eleven-year cleanup totaled out to be a staggering one billion, which was more than the actual construction of the power plant. With many having to leave their homes, anti-nuclear protests happening, reading news articles about plant negligence by the company who runs it, and the details of the plant disaster itself, made nuclear energy operations difficult.
It also didn’t help that twelve days before the accident, a movie about a nuclear power plant cover up called The China Syndrome was released. All of these barriers drove utility costs up which made investors wary of financing the development of new reactors. The nuclear industry needed to break these barriers to continue the use of nuclear energy, they needed to slowly change public opinion and their views.
Their were many changes to regulations in the following years that would impact how we maintain nuclear power plants today. The nuclear industry establish both the Institute of Nuclear Power Operations and Nuclear Safety Analysis Center, in response to the accident. Both of the organizations would collaborate to improve plant designs and operating protocols.
In addition, the Nuclear regulatory commission established a new department, which would be known as the Office for Analysis and Evaluation of Operational Data. This department would be staffed with 40 individuals who would study abnormalities in nuclear power plants, fifteen times a year. The department would also send out bulletins, warning of possible hazards or scenarios.
