This is meant to be a starter nuclear power plant for a new factory. As such, it doesn't require bots for operation and will moderate fuel cell insertion while storing excess energy as steam. Fuel goes in on the bottom belt, and spent fuel returns on the top belt.
The plant will need to be manually started with a single fuel placed in each reactor. If the inserter arms don't start with power from another source, you'll probably need to manually remove/insert the next fuel cell into each reactor as well, as a single inserted pair won't bring it up to temperature.
The plant does have space for roboports to the left of the reactors, should you wish to convert it to bot operation or to expand your network. Just be sure to leave the steel chests and and inserters alone, as they are a part of the logic.
With 20 tanks, it can hold 500k units of steam. If the total units of steam in the tanks is less than 100k, and there is a single empty fuel cell in each the steel chests, it will remove the empty fuel cells from the chests and insert fresh ones into the reactors. A complete burn of two cells with two reactors looks to generates around 320k steam, so at 100k+320k the tanks can hold a complete burn with no energy draw. The plant can provide a steady state 159 MW, and can stretch to hit 162 MW draining stored steam.