Three Mile Island Meltdown

On March 28, 1979, Three Mile Island near Harrisburg, PA was running at about 100 % power when it immediately turned off after a pump that supplied cooling water quit running. Pressure and temperature level increased in the activator, creating a pressure safety valve to open. The safety valve opened as it was supposed to, and water and steam began draining from the reactor to a tank in the basement of the reactor building.

As the pressure returned to normal, the shutoff valve should have closed. However, unbeknown to the plant operators, the shutoff valve stayed open. It continued to be open for more than two hours, permitting water that covered and cooled the fuel core to leave from the reactor system, causing the fuel to overheat.

Nonetheless, instrumentation in the TMI control room showed to the plant operators that the valve was shut and that too much water was being infused into the reactor vessel. Therefore, plant operators didn’t replace the water that was shed as a result of the open valve.

As the pressure continued to go down, an increasing number of coolant turned to vapor, causing too much vibrating in the main coolant pumps. The vibration made the plant operators at Three Mile Island, who didn’t recognize the reactor was suffering a loss of coolant, to close the pumps.

The reduction of pressure and water caused a big steam bubble to form in the top of the reactor vessel, preventing the flow of cooling water through the core. Without coolant, core temperatures increased above the melting point of the fuel cladding and the uranium fuel.

50% of the fuel melted before the flow of coolant was restored. Likewise, the cold cooling water shattered several of the hot fuel rods. All of the fuel was destroyed. As a result, over 600,000 gallons of radioactive cooling water went into the basement of the reactor building and storage tanks in the auxiliary building, infecting them.

Furthermore, a small amount of radioactive material was launched right into the atmosphere from the ventilation stack of the auxiliary building to ease pressure inside the reactor building.

Health Effects

The TMI accident created no injuries, and at the very least, a dozen epidemiological research studies performed since 1981 have actually found no noticeable direct health effects to impact to the populated area around the plant.

In 2003, a federal court dismissed the case of 2,000 plaintiffs seeking damages from the former plant owners. The court claimed the plaintiffs had actually failed to present evidence they had obtained a radiation dosage big sufficient to cause possible health and wellness effects.

Years of research study and clinical studies have actually shown no unfavorable health issues to the residents around the plant. People that suffered economic losses as a result of the evacuation after the incident were paid quickly, validating the performance of the industry’s obligation insurance coverage protection under the Price-Anderson Act. On top of that, companies were compensated for loss of revenue, and the state and local communities were compensated for costs accrued from responding to the accident.

Safety Measures

Two weeks after the 1979 Three Mile Island accident, President Jimmy Carter assigned a 12-member commission, headed by the late John Kemeny, who was then the president of Dartmouth College, to explore exactly what had taken place and the possible influence it would have on the health and wellness of the public and plant personnel.

The Kemeny Compensation provided a report in October 1979, recommended that the industry creates its own criteria for excellence. The commission also pointed out a need for agency-accredited training institutions for nuclear plant operators and operation supervisors.

The Nuclear Regulatory Commission (NRC) also moved promptly, setting up a group to research the accident. Attorney Mitchell Rogovin headed the team, and its conclusions coincided with those of the Kemeny Commission.

In 1979, the accident at Three Mile Island (TMI) was due to the failure of equipment and the inability of the plant operators to understand the condition of the nuclear reactors. A slow reduction of cooling water to the reactor’s heat-producing core caused a part of the fuel rod cladding and uranium fuel, as well as the release of a minimal amount of radioactive material.

The TMI accident caused no injuries or fatalities. On top of that, experts wrapped up that the quantity of radiation launched right into the environment was too tiny to result in noticeable direct impacts to the residents living around the plant. At the very least, numerous epidemiological studies have backed up this fact.  Both the industry and the federal government responded swiftly and also emphatically to the accident at Three Mile Island. As for more course of action, the industry formed the Institute of Nuclear Power Workflow (INPO) to ensure excellence in training, plant management, and operations.

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