Err no its not. Lots of old nuclear use pretty cool hot side, like around 300C, so to produce a GW of electrical power they pump out 3-5GW of heat. It is well within normal industrial scale cooling capabilities. Old coal was like that as well. These days we push for higher hot side temps, which costs far more up front, but uses less fuel so hence long term savings.
This thing has by requirement a very hot hot side. The primary circuit won't run that hot, but having in the 700C range is not out of the question. Even modern power plants (coal or gas) often use 5% to 10% of the energy the generate for there own operation. 20% is clearly higher than that and often 10% is often quoted as the required figure for commercial plants, but you don't need some other costs to shift to move that up a factor of 2.