[Snerdley]

What would happen if a suitcase nuke was set off at a nuclear palnt? Would the fissible uranium and or plutonium material at or in the reactor increase the overall yield of the detonation as a secondary of some type?

Speaking as an x-Nuke (USN), no it wouldn't cause any addional nuclear reaction. Our reactors can only sustain a chain reaction as long as there is liquid water cooling down(and slowing down neutrons in the core. If the pressurized primary coolant system (water, albeit radio-active) is breached, that superheated water will flash to steam and escape into the environment, probably causing evacuations and widespread panic about radiation poisoning. The reaction itself in the core will stop almost immediatly (even if the boron control rods don't scram the reactor) since without the water, the neutrons produced by the fission will be traveling too fast to continue the chain reaction.

In order for uranium to self sustain a fission reaction, you'd need a critical mass of weapons grade uranium and have it dense enough to catch these escaping neutrons. This is done in a bomb by compressing the uranium with chemical explosives inward in a very precise pattern. This can't happen randomly by an external explosion.

I hope this alleviates your fears of a nuclear plant becoming a nuclear bomb. It could only become a radiation hazzard like a radiological bomb. This isn't to say that radiation hazzards aren't dangerous, but there is no chance of a nuke plant wiping out an entire city via a nuclear explosion.

-Snerdley

"Never start a fight, but by God, ALWAYS FINISH IT!"
-Captain John Sheridan
Earth Space Station Babylon 5

[Mat_Helm]

I understand your point , but my question was concerning a nearby detonation of a low yield .5Kilo or 1 Kiloton device within 100 yards of the reactor. The explosion would breach the containment wall and reactor and vaporize most of the reactor core. Would this additional material that is fissionable and in a tremendous quantity add to the energy released? If it was to far away and less densly packed than a warhead to add energy than would all this material be thrown up into the atmostsphere and add to the horrendous amount of radioactive fallout.
Fusion bombs are two and three stage tritium, but densely packed around the core of the fission central core. What happens when a nuke goes off near a large commerciol reactor with 20 tons of fissionable uranium in its core?