如果在核加工廠上引爆中子彈，對廠內的低濃縮鈾或其它放射性物質，會引起甚麼作用 ？

This would cause neutron activation of various substances on site, but there wouldn't be any nuclear explosion.

Low concentration uranium will not reach criticality (i.e. the state that chain reaction starts) merely because of neutron bombardment.

The only result is the enhancement of radioactivity in the explosion site.