Quote:
Originally Posted by Catfish
Right, citing Wikipedia is sometimes a bad idea; the TV always 
I just do not understand why it was built that way, but it is stated that it was an "effective" (read: cheap) method to generate a lot of energy while breeding plutonium for weapons of course.
So i have two questions:
1. Why are just of all the upper control rods tipped with nuclear graphite at the lower end, so the reaction is being fuelled just of all when you usually want to decrease the reaction.
The graphite fuels the reaction, and also the displaced water (by lowering the control rods) leads to less water and the remaining rest getting hotter, and fast.
2. I wondered whether the TV flick showed the central hall floor with the upper shield cover correctly (?) when those caps began to 'dance', popping up and down:
(20 seconds into the film)
As far as i learned the center area being shown here consists of individual removable steel-graphite plugs, located over the tops of the channels.
So is it possible like as shown that they were forced up by expanding water steam, hydrogen and maybe even the helium-nitrogen atmosphere usually contained in the reactor vessel (20 seconds into the film)?
I also wonder where the controls are to lower the control rods, i do not see any motors or linkage  |
The idea was not to breed Pu for the weapons, the idea was to take the well known Pu creating reactor and use it for civilian purposes because building a low density reactor (low pressure, does not require specially made pressure vessels, you can refuel it during operation etc) reactor using natural uranium (no need to enrich it, they didnt manage to get quite that far) seemed like a good idea.
Hot fuel leads to a slower reaction all other things being the same. Broadly speaking the graphite is used to balance reactivity out with the water it displaces. The problem is the positive void coeff which was critical due to the low ammount of feed water going into the reactor, which meant that it was boiling from the bottom. Neutron fields in various heights of the reactor depending on the position of the control rods:
The issue with the ends effect was fixed by making the graphite tips longer so that they would produce the same effect through the entire height of the reactor.
No idea about the pop up effect, I think the motors are between the upper hull and the floor:
