I have a question about nuclear weapons. Anyone here know much about them?

[PamW]

91. WRONG - that IS why Chernobyl exploded..

The Chernobyl RBMK had a number of design defects.

One was that it was "over-moderated" and hence had a positive temperature coefficient. That is when the reactor got hot, the reactor wanted to INCREASE in power as it got hotter. The IFR is the opposite, it had a negative temperature coefficient.

Additionally, the operators were performing their experiment in the middle of the Xenon transient. The original plan was to carry out the experiment right after they lowered power. However, the load controller in Kiev called and asked the plant to remain online at reduced power. They were finally released to go offline about 12 hours later.

When you shutdown or lower the power on a reactor, it undergoes something called a "Xenon transient" in which you get a temporary build up of the very potent neutron poison Xe-135. See:

http://en.wikipedia.org/wiki/Xenon-135

Failing to manage this xenon transient properly caused the Chernobyl reactor power to overshoot ~100x normal causing a steam explosion.[citation needed] The xenon burn-out rate is proportional to neutron flux and thus reactor power. If reactor power doubles, the xenon burns out twice as quickly. The larger the rate of increase in reactor power, the faster the xenon burns out and the more quickly reactor power increases.

The power increase due to the loss of coolant flow as induced by the experiment was the trigger. (Coolant flow decrease -> increase temperature -> higher power -> runaway ) Once that happened, the unstable nature of an over-moderated reactor, augmented by the Xenon-induced instability, sealed Chernobyl #4 reactor's fate.

PamW