No, the nuclear material was just an illustration. Here's a few things I found regarding explosions.
The presence of hydrogen gas in air can present a serious risk of explosion. An overheated container of dry nitrocellulose is believed to be the initial cause of the 2015 Tianjin explosions.
One unusual phenomenon occurs when dense, low-volume powders are used in large-capacity rifle cases. Small charges of powder, unless held tightly near the rear of the case by wadding, can apparently detonate when ignited, sometimes causing catastrophic failure of the firearm. The mechanism of this phenomenon is not well known, and generally it is not encountered except when loading low recoil or low-velocity subsonic rounds for rifles. These rounds generally have velocities of under 1100 ft/s (320 m/s), and are used for indoor shooting, in conjunction with a suppressor or for pest control, where the power and muzzle blast of a full-power round is not needed or desired.