This four reactor nuclear plant uses the new factorio 2.0 ability to read temperature and fuel settings directly from the reactor. The plant is completely lossless despite not having any steam storage. It will reload once the temperature is below 600 degrees, all the reactors are empty, and there is one fuel cell ready in each of the chests.
The seemingly unnecessary extra heatpipes are there for heat storage. Even if the load is completely removed the second the reactors reload at 600 degrees, a full burn of the fuel cells will heat up the reactor to about 970 degrees. That is below the 1000 degree cap at which energy starts being lost.
With the fluid rework in 2.0 pipes can carry much more water, and five pumps are no longer necessary to run a four reactor plant. There are two water input pipes, through they can actually even be hooked up to the same pump.
The plant doesn't require bots to run, making it easier to get up and running early in a game. Just supply fuel cells on the input belt and provide it starter power so that the inserters run. Manually priming the reactor isn't necessary. So long as fuel is present and the plant has power, it will start on its own.
Edit: Updated to version 2. Has filters on the inserters taking fuel off the belt (thanks to Jody in the comments). Also removed a couple stray unnecessary pipes.