Spent Fuel Storage

Every nuclear plant in America stores its own waste on-site because the permanent repository that was supposed to accept it 25 years ago was never built. The interim solution has become the de facto permanent one.

Spent fuel storage uses two methods in sequence. Spent fuel pools hold freshly discharged fuel assemblies underwater for 5-10 years while their most intense radioactivity and heat decay. The water provides both radiation shielding and cooling. After sufficient cooling, assemblies are transferred to dry cask storage: steel and concrete containers that rely on passive air convection (no pumps, no electricity needed) to dissipate remaining heat. NRC-licensed dry casks are designed for at least 40 years of outdoor storage, with license renewals expected to extend this to 100+ years.

The US currently stores roughly 90,000 metric tons of spent fuel at 75 reactor sites in 35 states. About two-thirds is in pools; one-third in dry casks.

The safety question. Spent fuel pools require active cooling (pumps circulating water). If cooling is lost and the pool boils dry, fuel can overheat and release radioactive material.

Are dry casks safer than pools?

Yes, by a wide margin. Dry casks are passive (no moving parts, no electricity), sealed (no pathway for release during normal operation), and robust (designed to survive earthquakes, tornadoes, floods, and aircraft impact). The NRC has stated that dry cask storage is safe for at least 160 years. The main argument for accelerating the transfer from pools to casks is reducing the vulnerability window during which active cooling must be maintained.

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