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How to Dismantle an Atomic Power Plant

PG&E just announced it will close the Diablo Canyon nuclear plant near San Luis Obispo. But just how, exactly, do you demolish a fission reactor? Here’s a hypothetical timeline based on past decommissionings.


2016–19 PG&E will develop a decommissioning proposal for the California Public Utilities Commission that will update the cost estimate and map how to tear down the plant. A PG&E spokesperson says the company is now beginning to put together the group that will write the plan.

2018–24 PG&E will obtain 2,000 gross gigawatt hours of energy efficiency savings (a gigawatt is one billion watts) to offset the loss of Diablo Canyon. How exactly it’ll do that it’s not saying.

2019 PG&E will likely submit a license renewal application with the Nuclear Regulatory Commission for storage of high-level nuclear fuel onsite.

2024–25 Units One and Two will close—no more fuel will be added to their reactors, and they’ll no longer put power on the grid. Legally, the site must be decommissioned within 60 years. PG&E could let it sit and cool for up to 50 years before beginning demolition, but some estimates suggest it could begin within 5 to 10 years of the closure. What’ll happen to the site while PG&E waits? Maybe it will become a state park! (Probably not.)

2025–30 PG&E will procure another 2,000 gross gigawatt hours of energy resources.

2031–45 PG&E will increase its renewable energy production to 55 percent of total sales.

2074–75 (approx.) Decontamination will begin. Low-level waste like contaminated rags and filters will likely be packed in barrels and shipped on rail to be stored at a repository, maybe in Utah. At one point, there were discussions about burying high-level nuclear waste from Diablo under Yucca Mountain in Nevada, but those stalled out. So for now, the high-level waste from Diablo will probably be stored onsite in concrete-and-steel casks. Workers may use robots to carefully dismantle equipment and the enormous pipes that reach the ocean’s edge. The job could take years or even decades to complete.

2084 Deadline for decommissioning Unit One.

2085 Deadline for decommissioning Unit Two.

26,095 About half of the plutonium-239 produced at Diablo Canyon will have decayed into relatively harmless uranium-235.


Originally published in the September issue of San Francisco

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