ThreeMileIsland

In 1979, the Three Mile Island (TMI) nuclear power plant in Pennsylvania experienced a major accident. The issue started with a problem in the non-nuclear part of the plant, which led to a shutdown of the reactor. Due to a valve malfunction, coolant water leaked without the plant workers knowing. The White House was notified and people within a 5-mile radius were advised to evacuate. Concerns about a hydrogen bubble forming in the reactor were also raised. The accident released a small amount of radiation, but no abnormal number of cancers were found in later years. The cleanup took 12 years and cost nearly $1 billion. The accident led to significant changes in the nuclear industry, including improved training and emergency preparedness. People living near the plant believed they suffered health effects and many had to leave their homes. The accident could have been prevented with better training and quicker action. Fremont Island is a nuclear power plant located in Middletown, Pennsylvania. At 4 a.m. on Wednesday, March 28, 1979, the plant began to experience issues in one of the non-nuclear areas of the power plant. This issue prevented the main feedwater pumps from sending water to the steam generators to aid in removing heat from the reactor core. This then caused the reactor to shut down. The pressure began to increase in the primary system, so the release valve was opened to help control the pressure in the reactor. This valve was located at the top of the pressurizer. When the pressure began to drop to the proper levels, the valve should have been closed, but instead it became stuck open. The plant staff were unaware that cooling water was pouring out of the open valve. When looking at the instruments in the control room, it was indicated that the valve was closed, but this was in fact wrong. Warning lights and alarms started to go off, and the plant workers were unaware that the plant was losing coolant through the valve. The White House was notified, and all non-essential personnel were ordered to leave the plant's premises. There was a concern about radioactivity being exposed to the atmosphere above the plant. On the evening of March 28, the core of TMI-2 appeared to be cooling down, and the reactor appeared stable. On Friday, March 30, a new concern arose of radioactivity being released from the plant. This was when the governor advised anyone vulnerable to radiation who lived within the 5-mile radius of TMI to evacuate the area. A large hydrogen bubble was starting to form in the dome of the second reactor, and there was a fear that the bubble might burn or explode and break the vessel. By April 1, the hydrogen bubble had appeared to decrease in size. The TMI accident released around 0.08 millisieverts to the population who lived within the 10-mile radius of the plant. This dose is equivalent to a chest X-ray. The Department of Health kept a record of people who lived within the 10-mile radius over 18 years. More than dozens of independent health studies have been done on the accident, and there has been no evidence shown of any abnormal number of cancers related to TMI in the leading years after the accident. The dose of radiation that were released from the accident were not far above the background radiation levels. The only effect they found detectable was the physiological stress the population was affected by during and shortly after the accident. The cleanup of TMI-2 costed around $972 million and took over 12 years to clean up. In July 1980, over 43,000 caries of krypton were removed from the reactor's building. Fuel from the reactor started to be removed in October of 1985, and the fuel wasn't completely removed until January 1990. 342 fuel canisters were shipped to the Idaho National Laboratory, where they sent in long-term storage to decay. TMI Unit 2 was permanently shut down due to the accident in 1979, and TMI Unit 1 was recently shut down on September 20, 2019. Many personal errors and other failures during the TMI accident changed the nuclear industry and the NRC. Some of the significant changes that occurred were strengthening training in the industry, emergency preparedness, and installing more equipment to help monitor radiation levels. The population who lived around the area believed that they had many health effects due to the exposure to TMI. Families who lived within the radius packed up everything they could and left the area. They were unsure if they would ever be able to return to their homes. This accident could have been prevented if personnel had better training and checked sooner when the issue first occurred on the reactor.