Microwave appliances do not contain or produce radioactive materials, so they cannot "blow up" and spread radioactive dust. Microwaves work by using electromagnetic waves to generate heat and cook food. They have a magnetron, which generates microwave radiation, but this radiation is non-ionizing, meaning it does not have enough energy to cause ionization in atoms or molecules, which is what makes radiation harmful.
The main safety concern with microwaves is the risk of thermal burns from hot food or liquids, not radiation exposure. When used according to the manufacturer's instructions, microwave ovens are generally safe to use. It's essential to avoid using any damaged or malfunctioning microwave appliances, as with any electrical device, as that can pose other safety risks unrelated to radioactivity.