‘A combination of failures:’ why 3.6m pounds of nuclear waste is buried on a popular California beach

The San Onofre nuclear power plant shut down years ago - but residents and experts worry what will happen with the waste left behind

More than 2 million visitors flock each year to California's San Onofre state beach, a dreamy slice of coastline just north of San Diego. The beach is popular with surfers, lies across one of the largest Marine Corps bases in the Unites States and has a 10,000-year-old sacred Native American site nearby. It even landed a shout-out in the Beach Boys' 1963 classic Surfin' USA.

But for all the good vibes and stellar sunsets, beneath the surface hides a potential threat: 3.6m lb of nuclear waste from a group of nuclear reactors shut down nearly a decade ago. Decades of political gridlock have left it indefinitely stranded, susceptible to threats including corrosion, earthquakes and sea level rise.