Display MoreLemme explain why this won't work even without a need for testing in either the simulation nor in Minecraft itself.
The central Cooling Cells can only reduce their heat level by 1 per each tick. Each Cooling Cell here is gaining approximately 30 heat per each tick (4 heat/tick from each U. Cell*pulses of each U. Cell*# of U. Cells next to one C. Cell = 4*3*3 = 36). Every C. Cell besides those two will be gaining 12 heat/tick (4*1*3=12). As that stands, the reactor will melt many of the outer elements by around 800 ticks. Once the C. Cells have all gone by the wayside, the reactor will meltdown in just 36.9 ticks (270+ heat excess).
This reactor would require an excessive amount of ice in order to even hope of running without massively failing (you'd need approx. 12400 Ice blocks to keep it from exploding after the C. Cells have all popped (probably more though... try around 13500). It'd be a huge undertaking to make a system that could produce the ice necessary to keep the reactor from heating up.
Edit: Tested in the sim and the reactor makes to around 530 ticks before it loses most of the C. Cells and builds up reactor heat alarmingly fast (239 excess heat). By the time the rest of the C. Cells have popped, the reactor has over 100k in heat.
That design isn't great but for example I made a design, on the site it said +10-20 heat or so and 50eu, in the game it was 0-5 heat (for cells) and 80eu/t what I'm trying to say is that the site isn't always correct
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(by modifiying someone's design forgot name 
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only uranium cells) that type
