Everything That Went Wrong on 3-Mile Island

Summary

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Takeaways

• 😀 The Three Mile Island nuclear accident, the biggest in U.S. history, occurred on May 28, 1979.
• 😀 The disaster was smaller compared to other nuclear accidents like Fukushima and Chernobyl but still served as a warning about how small mistakes can lead to major consequences.
• 😀 Unit 1 of the plant was completed without issues, but Unit 2 faced delays, technical failures, and falsified data, which set the stage for disaster.
• 😀 On March 28, 1979, the feed water pump failed, causing a shutdown and creating conditions for a potential meltdown.
• 😀 A stuck valve failed to close during the emergency shutdown, causing steam to vent continuously, reducing the cooling water levels in the reactor.
• 😀 The backup emergency pump failed because its relief valve was left closed after maintenance, preventing it from starting and worsening the situation.
• 😀 Operators in the control room were misled by faulty instrumentation, which made them believe the reactor was properly cooled even though it wasn't.
• 😀 Due to human error and miscommunication, the water flow was shut down, making the reactor even hotter and leading to a partial meltdown of the core.
• 😀 After three hours of confusion and missteps, the core melted down to 60% of its full capacity before anyone realized the gravity of the situation.
• 😀 The aftermath included a massive cleanup that lasted over 13 years, costing over $1 billion. The plant's decommissioning process will take 60 years.
• 😀 The Three Mile Island incident led to widespread fear of nuclear power, but no immediate health effects were observed in the nearby population.

Q & A

What was the main cause of the Three Mile Island nuclear accident?

The primary cause of the Three Mile Island nuclear accident was a series of failures starting with a pump malfunction that caused a cascade of technical issues, including a stuck relief valve, faulty backup systems, and human errors in managing the reactor.

How long did it take for the Three Mile Island plant to be decommissioned after the incident?

It took nearly 14 years for the cleanup from the Three Mile Island incident to be concluded, with the final cleanup completed around August 14, 1993.

What role did human error play in the disaster?

Human error played a significant role, as operators failed to notice key issues like the stuck valve and relied on faulty instrumentation that misled them about the reactor's cooling water levels. These mistakes contributed to the escalation of the problem.

Why were the backup emergency systems ineffective during the incident?

The backup systems failed because the emergency pump’s relief valve had been manually left closed after a test, preventing the backup pump from operating, and thus failing to provide the necessary cooling water to the reactor core.

What was the impact of the Three Mile Island accident on the local population?

Fortunately, no health effects were experienced by local residents, although it wasn't until two days after the incident that officials advised residents, particularly children and pregnant women, to stay indoors and keep their windows closed to avoid possible contamination.

How did the movie 'The China Syndrome' relate to the Three Mile Island accident?

The movie 'The China Syndrome', which dealt with a nuclear disaster similar to the Three Mile Island incident, had opened just 12 days before the accident. The sudden relevance of the film contributed to its success, earning four Academy Award nominations.

What technical flaw contributed to the confusion in the control room during the incident?

A major technical flaw was the lack of visibility into the actual water level around the reactor core, coupled with misleading control panel readings that made it appear as though the reactor was properly cooled when, in reality, it was filling with steam.

What happened to the reactor after the meltdown?

After the meltdown, 60% of the reactor core was severely damaged, but the steel bottom of the reactor held, preventing a full meltdown. The cooling systems were eventually restored, and the situation was contained before it worsened.

Why was the Three Mile Island plant shut down in 2019?

The plant was shut down in 2019 not due to technical issues, but because its operator, Exelon Corporation, was no longer earning enough money to sustain its operation. Despite the plant's license being valid until 2034, Exelon decided to close it due to financial concerns.

What was the outcome of the cleanup and decommissioning process?

The cleanup of the Three Mile Island incident took several decades, and the process involved handling hazardous materials, including cleaning 2.3 million gallons of wastewater. The plant's reactor unit 2 was permanently shut down after the disaster, and decommissioning took nearly 60 years and over $1 billion to complete.