[s0rce]

Do you mean a piece of the reaction wheel getting thrown across the room? You could shield that with something like they do on jet engines to avoid turbine blades being launched through the fuselage. I think the object itself is heavy enough compared to the energy in the reaction wheels that it would just fall over.

[newaccount74]

I think a stainless steel reaction wheel is unlikely to break. Now those 3D printed reaction wheels using ball bearing balls for weight are another story: https://www.youtube.com/watch?v=AJQZFHJzwt4