4 ms·
Modern nuclear plants have two cascaded cooling loops and run at about 33% efficiency. This means that a 1000MW plant has 3000MW of thermal energy to manage at
by mschaef 13y ago
Modern nuclear plants have two cascaded cooling loops and run at about 33% efficiency. This means that a 1000MW plant has 3000MW of thermal energy to manage at full load and 2000MW of energy to dissipate safely. The systems to do this take a great deal of power to run, so can't be bootstrapped off of batteries.
Also interesting is that power prices will occasionally go negative in cases where there's a 'surplus' of generation. What's happening in these cases is that generation owners are making the judgement that its more cost effective to pay people to take their power than it is to shut off their plant. Shutting down a big plant is an event, and it takes a while to get them back running. Sometimes, shutting them down doesn't make sense.
- VLM 13y agoAlso about ten percent of the heat energy is released later on, delayed, decay heat and all that. So there is no off switch. If you were running at 3000 MWt, 5 minutes after you scram you still have to do "something" with 300 MW of heat, and you don't want to have to rely on just one diesel. So the feds require multiple sources of power to operate, one of which is usually the diesel and one is the the grid. Lets say your control and cooling systems require 5% of the heat they handle, that means your 3 GWt nuke would require an absolute minimum of 15 MWe to spin down. Or four if you want to run off grid so you've got two completely independent sources of power each with a 24x7 hot backup (I believe no one ever took the NRC up on that offer, but I could be wrong)