Is there a risk that SRBs (Solid Rocket Boosters) can explode?
No. The SRBs used for the Space Shuttle use what is referred to as a 1.3 Class propellant. This propellant does not detonate (blow up). A stick of dynamite or other explosive uses materials that are designed to detonate, which means they consume all of their explosives within a matter of milliseconds creating a large explosion. By comparison, the materials used in a SRB are designed to burn at a prescribed rate. These propellants burn at even a slower rate in the absence of pressure. So, if there were a catastrophic failure of the SRB, like a case rupture, the internal pressure would be released and the remaining propellant would be expelled and burned at a slower rate. While this produces spectacular fireworks, the resulting environment is relatively benign compared to an explosive event. (During a satellite launch from Cape Canaveral a Delta II failure shortly after liftoff resulted in impressive fireworks, but the satellite flew off the top of the rocket intact until it impacted the
