Original: Typical sources of exposure of electronics to ionizing radiation are the Van Allen radiation belts for satellites , nuclear reactors in power plants for sensors and control circuits , residual radiation from isotopes in chip packaging materials , cosmic radiation for spacecraft and high-altitude aircraft , and nuclear explosions for potentially all military and civilian electronics .
Simplified: Such radiation occurs in outer space and when flying at high altitudes in the Van Allen radiation belts . They also occur in nuclear explosions , and near nuclear reactors and other sources of radiation .