x4 Reactor Blueprint book ("The Nuclear Book V1.1") Notes:

Puts out peak power production capacity of ~480mw, via steam turbines.

Features:
- Smart Burns fuel, only actively burns fuel when needed, and waits for steam tanks to drop to a low enough threshhold before burning more fuel again, which maximises fuel efficiency
- Green Indicator lights show when the system is actively burning fuel, a nice visual indicator* (*also shows burn state w/ the A signal state)
- Keeps track of how much fuel has been Expended since system was started (by default this value is multiplied x4, adjust the value of the arithmetic combinator (top left of reactors) to 1 instead of 4 to make it show 1:1 how much fuel it's loaded in and expended)
- Has alarm/alert system, to notify the player of a problem w/ the reactor (water running out, fuel running out), outputs a nice Factorywide alert to the message area, showing which setup (2x2 reactor blueprint, incase u put multiple of these down) is having problems.

By Default, is Designed to be fed via Robot Logistics, but can be converted over to belt feed (see below)
Uses 6 pumps (3 per side, each feeding directly to their own pipe) to feed the water.

Probably also worth reading the signal legend, and figuring out how the system works/the different run states before using, so you can know how the system operates for yourself.
(Please note when first starting reactor for first time, it takes a while to initally start, as the heat pipes have to rise above ~500c, after which the system will start running as normal.)

The Included enrichment blueprints in the book are also designed to be bot fed, but a Belt fed version of the reactor exists in your blueprint library.

after analysis: the fuel input chest stack size does NOT matter, all the system is doing is using the 4 combinators (1 connected per chest, 4 total) to generate enough A=1 signals to get to the normal operating range, so all that is needed to convert the system to robot-less, is to simply to:

For 4 center chests (the requester chests, aka fuel chests ; 4 total, 2 on top, 2 on bottom):
> Place Steel Chests in place of requester chests
> Wire them with RED wire to the Decider combinator next to them (topleft, bottomleft, bottomright, topright)
> Set chests to "Read Contents" Mode.

For 4 outside chests (the active provider chests, aka the spent fuel eject chest ; 4 total, 2 on top, 2 on bottom):
> Just simply omit these for a Steel chest, they're not connected to the circuit network so these can be theoretically anything, can have inserters pull out of these and bring the spent fuel out on a belt and deliver it to another location for it to be processed back in to U-238.

All the chests do anyway is just provide fuel level empty input to the system, if the value of uranium fuel cells in any of the 4 drop to 0, the system drops eventually to an error state which triggers the alarm/alert, notifiying the player of the problem. each chest (assuming "Uranium Fuel Cell" > 0) should under normal conditions add ONE A value to the system (A=1 x 4, aka adds 4 to the A total), which if running properly brings the system to A=11 or higher, the normal operating range.
In theory, simply just feeding the Uranium fuel cells directly to the 4 fuel chests (2 per side, top and bottom) and limiting the chest to a decent value (i think ~2 stacks is a good value, 100 fuel cells stored in the buffer) won't cause any issues, system only error states if the fuel chests drop below 0 (aka, no fuel in one of any of the 4 fuel chests), so as long as they're all topped up perepetually, system runs perfectly fine.


Signal Legend:


T signal == Time, somehow is hooked up to timer circuit (bottom right of reactors) to tick down after loading fuel (when it loads fuel, it reads the hand contents of the fuel inserters, and when it reads uranium fuel > 0 on the red circuit line (seprate from the counter value, the uranium fuel value in green), it starts the timer, which counts down til the end of the fuel burn time in the reactors, and when it runs out, outputs T= -1, and rises the state of 12 (waiting for steam to drop below X threshhold)

X Signal == Minimum steam threshhold, of the x4 steam tanks nearest to the reactor, it use this constant to set a minimum level for the steam to drop in the 4 tanks, if it drops below this value, the A state rises (normally to 13, then immediately back down to 11) which triggers the system to load fuel. By default with the blueprint, this is set to 16k with the constant combinator (directly below reactors), can POTENTIALLY be adjusted, but unknown what effect this would have on the system's efficiency. Probably best to just leave it 16k.

"Steam" Signal == The current sum of all the fuel in the x4 steam tanks nearest to the reactor, if this value drops below the X threshhold (~16k steam), the A state rises (normally to 13, then immediately back down to 11), which triggers the system to load fuel

Green "Uranium Fuel Cell" == How many fuel rods the system has burnt, roughly gauges it based on what is assumed to be a counter circuit (top left of reactors), the only oddity is, for some reason it is set to multiply it by 4, possibly for the included indicator light blueprint (which u place on top of the reactor setup) to work properly, however from testing, you can easily adjust the value of the arithmetic combinator to "Uranium Fuel Cell * = 4" to 1, and this will simply make the system show 1 to 1, how much fuel it's inputed to the reactors over time

Green 1 == As far as i can tell, purely used for the lights, just puts out this signal from the same combinator for the X threshhold for the lights to use to indicate when system is running (the lights turn ON if T > 0, which is usually during A condition 11 (aka "active burning fuel" state)), it just makes them green, otherwise they'd just be the default white color.

A signal == Primary indicator/control signal, one of only TWO things that input to the red wires (the other being the signal from the fuel loading inserters when they hold a fuel cell, usually mid way into loading it into the reactor)
A Truth table with all the different system statuses is listed below:

-------------------- "A" Signal Truth Table: --------------------

A=10 or less == Error condition, only achieves this value if not being fed enough water or if the one of the 4 fuel chests is out (each combinator for gauging the water/fuel level puts out a A=1, these all add together to equal 11+ in normal operating conditions).

The Programmable speaker (bottom of reactors) is setup to output the "Error" alert ("A Zero Waste Reactor is missing fuel or water.") if this state is ever achieved (speaker looks for A equal to or less than 10, and if true, outputs the alert.), but is configured by default to NOT actually ouput noise, just to Alert the player to a fault condition.

A=11 == Actively burning nuclear fuel condition, gauges time off of the timer circuit (bottom right of reactors, next to t=12k and t=-1 constant combinators), which starts ticking down from 12k when state hits A=13, this aproximately gauges the burn time of the fuel cells, and when the fuel runs out (T= -1), it rises to A=12, waiting phase, and offloads the spent fuel

A=12 == Not Actively burning nuclear fuel ; running off steam condition, this is triggered (usually) once the timer stops (t=-1), and this state continues until the steam tanks (x4 tanks nearest to reactors) drop below ~16k steam (set by the X constant), in which the system rises to state A=13

A=13 == Load Fuel condition, this state only briefly exists when the steam drops low enough, AND the system is not actively burning fuel, this state enables the fuel loading inserters for only JUST long enough to load 1 unit of fuel into each reactor (4 total), which almost immediately starts producing more fuel, raising the steam threshhold above ~16k, then instantly lowering the state back down to A=11 (active burn state).