Radiation in California Cities: No Major Incidents

No California city has experienced a major radiation leak or disaster affecting the general population.

Nuclear Context

• Operating plants: Diablo Canyon (San Luis Obispo) — last operating; scheduled 2024/2025 closure
• Decommissioned: San Onofre (2013), Rancho Seco (1989), Humboldt Bay (1976)
• Research reactors: UC campuses, national labs (LLNL, LBNL, SLAC) — highly regulated

Minor Incidents

• 1959: Sodium Reactor Experiment partial meltdown (Santa Susana Field Lab, Ventura County) — remote, not a city
• 1970s–80s: Minor tritium leaks at plants — contained, reported, no public health impact
• 2011: Fukushima fallout detected in CA milk/rain — trace levels, no risk

Environmental Radiation

Background varies: higher in granite areas (Sierra), lower in basins. Cosmic radiation at altitude. Radon in some homes. All within normal ranges.

Emergency Planning

• 10-mile Emergency Planning Zones (EPZ) around Diablo Canyon
• Potassium iodide (KI) distribution
• Ingestion Pathway Zone (50 mi) for food/water monitoring

California's nuclear risk is low and managed. No city has been "hit" by radiation in the disaster sense.