Of that there can be no doubt. This is a good reason for making all such weapons illegal. Sooner or later, extremists will accumulate enough of this to build a crude device which could easily be carried by a vehicle, driven into a major city and detonated. The prospects are frightening. As in any industry, accidents happen.
Serious accidents can mean the spreading of dangerous radioactivity into the environment.
Several other less well known accidents associated with the race to build nuclear weapons occurred in the former Soviet Union, causing the contamination of hundreds of square kilometres of land. Since this had never happened before, no one knew what to do. After 2 days of uncontrolled burning, the reactor was quenched with water. Large amounts of radioactivity spewed out of the filter stack which was overwhelmed by the huge releases from the melted fuel. The extent to which this damaged people's health is still controversial today.