I've been trying out this mod and its alot of what i hoped for (more complex reactors, an element of danger, the requirement to cool it) but when i tried to use it in my world, the heat would almost never go over 528.44C.
Im using graphite fuel cells and they are being consumed but the low heat leads to problems with efficiency and long heat pipes. The pump for the eccs doesnt activate until much warmer and the start signal is constantly active so the problem doesnt lie there. Sometimes the reactor gets hotter but then it cools down again.
While im at it, ive noticed that you cant see fuel consumption in the description anymore, is it still 40MW? Im trying to calculate the fuel cost per second (or rather per hour xd)

thanks for any responses and sorry if the issue has been resolved elsewhere but the lack of a search feature on the discussion tab makes finding it difficult

I think if you have too many heat pipes (and attached heat consumers), the excess heat the reactor produces is not used to heat up the reactor core anymore, it is consumed 100% by the heat network. Try cutting of some parts of the heat network, the reactor should heat up then.
Fuel consumption and power output should be shown as signals (if I remember correct...). It varies according to the reactor setup, that's why it cant be shown in the description.