Inside the $1.6B Plan to Restart Three Mile Island | WSJ

- [Narrator] These blue dots represent a massive potential source of clean energy, dormant nuclear power plants. This dot here will be used by energy company Constellation to power AI servers. - All the electricity it generates will be sold to one company, Microsoft.

- [Narrator] Reviving nuclear has drawn support from Silicon Valley executives. - We see the need for gigawatts of power in the coming years. - [Narrator] Who could need over 90,000 gigawatts an hour to fuel AI by 2026.

- Please reopen the ones that have been shut. This is total madness to shut them down. - [Narrator] But if you look 500 feet south of TMI-1 you'll find the sight of America's worst nuclear meltdown.

- An unexpected release of more radiation today from the Three Mile Island nuclear power plant has led to a series of consequences. - [Narrator] Now, 45 years later, as Constellation begins to restart TMI-1. - I don't think an operating plant has ever been revived.

- [Narrator] Some experts urge caution. - Fundamentally, it's a dangerous technology. - [Narrator] Here's how the lights are being turned back on at Three Mile Island and why it's critical the process be done safely.

After TMI-2 melted down, TMI-1 generated power for 800,000 homes up until 2019, when it was shut down for financial reasons. Now, the team is moving forward with the historic restart of the plant without a regulatory roadmap. Current regulations are focused on building and relicensing, not restarting.

So the team says it'll take five main steps. Step one, they'll have to put uranium back into a decommissioned reactor. - The reactor vessel itself is probably about 70 feet tall, maybe about 14 feet in diameter.

It's physically sitting maybe 10 feet off the ground from where I am right behind us in the wall there. It's filled with fuel rods, that are 17 by 17. Each rod is a hundreds of fuel pellets the size of a Jolly Rancher.

- [Narrator] The heat created from those uranium pellets will warm water until it becomes steam, and travels through miles of pipes. That's why step two is to test the steam system. In the 1979 meltdown, a water pump broke here, stopping the flow to the reactor, causing it to overheat.

To lower that heat, operators released a pressure valve at the top of the reactor here, which got stuck open and dumped radioactive steam into the air. These pipes are being tested with electronic probes to make sure there are no cracks or holes, which could cause a similar leak and meltdown. On the other end of the pipes, is the turbine.

- It's got multi stages, 14 stages of blades. Where they get bigger and bigger and bigger as the steam imparts it's energy on it to create that rotational force, which then creates a magnetic field through a generator to put electricity on the grid. - [Narrator] These blades are being tested for strength to make sure they're up to the task.

That energy is then transmitted to the transformers, which carry electricity from the plant to the grid. Step three, replace them. - [Bryan] The voltage coming out of the transformers being stepped up to 345,000 volts to transmit across the grid, across this part of Pennsylvania.

- [Narrator] Once it's in use, Microsoft will pull an equal amount of energy from the same grid and use it to fuel its AI servers. Everything from these transformers, to the turbines, to the reactor is regulated from here, the control room. Step four, make sure all the controls work.

Currently, operators are testing each of them. When one works, these pieces of black tape are removed, a system the operators created themselves. But perhaps the most important step in reviving the plant is hiring new workers, who are trained to make sure 1979's meltdown isn't repeated.

- We learned so much from that particular incident. We developed site specific training programs. We required site specific simulators so operators could practice.

We require engineering degrees for supervisors. We require formality and procedures. So everything that was born from that particular accident has allowed the United States nuclear industry to lead the world in operational excellence and safety.

Our safety record is unblemished from that particular time. - [Narrator] The training process was created after this man, Victor Gilinsky, oversaw the cleanup after the 1979 meltdown. - We were outfitted in moon suits, (laughs) and we had this fishing pole with a meter at the end of it, and we'd sort of turn the corner and it'd go, click, click, click, click, click.

You know, (laughs) and so you didn't go there. - [Narrator] He realized that the industry wasn't focused enough on safety. - The problem was everyone came to it with the notion that a really severe accident was not possible.

- [Reporter] Three instances of human error, not equipment failure caused the accident. - The operators were confused, because they didn't understand the workings of the plant well enough. - [Narrator] The regulations he helped craft are now in flux due to a new law, the ADVANCE Act.

It calls for developing a new set of guidelines to restart plants and efficient, timely, and predictable license application reviews, which would streamline the restart process. But some experts say that's a slippery slope. - Of course, the people pushing it say, "We don't want any reduction in safety," et cetera.

But the fact is, safety is a subtle business. You know, you have to pay attention to the details. Ignoring small things can have large effects.

- [Narrator] While those guidelines are being written, Constellation is working with the Nuclear Regulatory Commission to bring the plant up to speed. - We'll have to go through every change in law, every new regulation, every operating experience that the industry has published, and make sure that we conform to those new standards. - [Narrator] The NRC's chairman said the restart is uncharted regulatory territory, but he's optimistic about the process.

Microsoft says their partnership with Constellation is an important step in promoting a diverse energy mix for a reliable grid. Currently, just two plants in the US, Three Mile Island, and the Palisades Plants in Michigan have restarts underway, and another is being considered as a potential third. But the promise of clean energy from reactors like TMI-1 isn't just fueling a future with AI.

Utilities are also seeing returns. After the restart announcement in September, the owner of TMI-1 has seen shares grow 46% to today, and as interest in restarts spreads across the country, some experts say a nuclear renaissance may be around the corner.