Nuclear fuel logic circuits

[Wrought]

So I've been trying to expand my limited knowledge of the nuclear side of power production. It seems the current meta for efficiency is to setup some combinators for the fuel cells going in and out of the nuclear reactor, along with a reading of the steam storage tank level. How and/or why is this better than just taking a reading off the steam storage tanks and inserting a fuel cell(s) when the steam levels are almost zero?

[garth033]

Reading both the steam and fule insertion and removal will allow you to only burn the rods you need.

Example, if you just read the steam the inserters will put as many rods into the reactor as possible (for example sake let's say this number is 5). You may have a setup that only requires you to burn one rod to top off, so the extra 4 are wasted.

That issue compounds when you use more reactors.

[Killcreek2]

The meta is to only load 1 fuel pod at a time, based on steam storage levels.

How each player does that is up to them, & there are several methods which work.

Simplest way is via circuit wires: input inserter only activates when the output inserter is holding an empty cell, output inserter only activates when steam levels are low. <-- loads 1 at a time, but requires manual startup & manual reboot if it stalls.

A more complex way involves 1 combi per reactor, to store 1 bit of data indicating if that core contains a fuel cell or not. Steam low trigger is similar to above. <-- still loads 1 at a time, but needs no manual intervention & can self-reboot.

Other methods exist, using more / less combis, but all are basically for the same purpose: fuel efficiency.

[Hedning]

Killcreek2, What do you mean by stalling and rebooting? My reactor never needs manual intervention and I'm not using anything fancy like combinators.

[Ryan]

I do it like you suggested pshurd. I read the steam tanks and refill when they get low. The trick is to have enough storage, so that no fuel is wasted when all the reactors get refueled. I use mods which have added many levels of buildings. For example Storage Mk4 can store 100k steam.

[Hedning]

There's a lot of storage capacity in the structures and pipes themselves, so you don't need many steam tanks. The key is building your heat exchangers very close to the reactors so that the max temperature runing continously is well below 1k degrees.

[Killcreek2]

Originally posted by Hedning:

Killcreek2, What do you mean by stalling and rebooting? My reactor never needs manual intervention and I'm not using anything fancy like combinators.

Stalling eg: brown-out causing a death-spiral (if the reactor is powered by main grid); or fuel supply interruption ~ if using the first method I listed above this may often result in empty reactor cores, requiring a manual reboot (ie; putting a fuel pod in each core).
Not a problem situation for everyone, but if you are a ditz like me & screw up the iron plate supply without realising... twice... it is a bit of a pita to open 20+ cores to put a fuel pod in each one.
I'd rather use an extra few combis so it automagically restarts itself as soon as I fix the supply problem.

I think it is great that there are a number of viable methods to choose from, each with different advantages. :)

Originally posted by Hedning:

There's a lot of storage capacity in the structures and pipes themselves, so you don't need many steam tanks. The key is building your heat exchangers very close to the reactors so that the max temperature runing continously is well below 1k degrees.

^^ This is great advice.
A full tank of steam contains 2.425GJ, whereas each reactor core can store up to 5GJ (4GJ at 900deg). Heat exchangers & pipes can store up to 500MJ apiece (400MJ at 900deg). That's quite a bit of latent energy storage in components that will be required anyway.

[Hedning]

Originally posted by Killcreek2:

if you are a ditz like me & screw up the iron plate supply without realising... twice... it is a bit of a pita to open 20+ cores to put a fuel pod in each one.

Brownouts shouldn't be a problem since both inserters are affected equally. But yes, running out of fuel would require a manual reboot. I never even considered that and because I'm using belts I have a natural buffer, so that's probably why it hasn't happened so far. Maybe some alarm that fuel is running low instead though since power outages brings many problems worse than just restarting the reactors.

[Wrought]

Originally posted by Hedning:

There's a lot of storage capacity in the structures and pipes themselves, so you don't need many steam tanks. The key is building your heat exchangers very close to the reactors so that the max temperature runing continously is well below 1k degrees.

Right, I only have 4 steam storage tanks for a single reactor but it takes 3-4 fuel cells to fill them back up once they are empty, so what do I gain by only loading one fuel cell at a time? Are single fuel cells somehow more efficient overall? I confess, I haven't bothered to do any of the math that would probably answer this for me. Everytime I get the motivation to run the numbers, I go kill bugs until the motivation goes away. :)

[Hedning]

If you load more than one fuel cell there is no way to stop or pause the reaction and let it cool down if you don't need the power. That's the only reason. If you are using it 100% all the time you don't need to bother with only loading 1. However because the more reactors you have the more efficient they become it is quite common to build huge overcapacity (at least when you start up, I never start with less than 8) and then just have them rest most of the time.