Holtec UMAX Canisters

Holtec UMAX canisters are 5/8-inch thick stainless steel containers used to store spent nuclear fuel at SONGS. Unlike thick-walled casks used internationally, these canisters have no inner liner, cannot be monitored internally, and are vulnerable to chloride-induced stress corrosion cracking from the coastal marine environment.

This is a significant departure from international best practices, where thick-walled casks (10+ inches of steel and concrete) are standard.