Fast Breeder Reactors and YOU!

How to use the fast breeder reactor.

The Basics:

A fast breeder reactor is the endgame of nuclear power. It can use liquefied molten uranium core fuel and produces only fission products, which given time can decay into harmless materials and be recycled. Core fuel is expensive to produce, but the reactor itself can be used to enrich cheap and easy blanket fuel into more core fuel, meaning that once the reactor has been filled with core fuel once you should never need to make more provided you keep it supplied with blanket fuel and reprocess everything correctly.

"Blanket fuel" and "Core Fuel" are the inputs. "Depleted Core Fuel" and "Enriched Blanket Fuel" the outputs. They are all molten liquids, which can be carried with pipes but cannot be stored in storages or carried by trucks, so all the loops for processing must be built close to each other. Keeping the loop going requires a constant input of steel, acid, salt and molten glass, as well as the requisite supply of fresh water and steam reprocessing, as well as a block of steam turbines to make the power. The reactor can self-regulate if it is provided with processing power.

Establishing the recycling loops

There are two output loops that need to be handled. Depleted core fuel is handled in a nuclear reprocessing plant. It requires acid and steel, as well as an input of molten glass. Using a whole blast furnace just for this is a bit overkill, but since molten transports have to be flat the only other option is relocating your glass production to near the reactor. You only need one of these plants, it has the capacity to handle two reactors worth of output and then a bit more, but you'll need a second if you want to reprocess old depleted fuel or MOX casks into blanket fuel, that'll come later.

Depleted core fuel is produced one for one when the reactor consumes core fuel. For each ten units of depleted core fuel, the reprocessing facility outputs eight units of core fuel and two units of fission products. So you get four units of core fuel back for consuming five units of depleted core fuel. This means you only need to replace one out of five.

The one vital thing that you cannot allow to happen is letting the output for depleted core fuel back up. That will cause a shutdown. If the output of enriched blanket fuel is full there's no consequences, and given perfect recycling this will eventually happen. If there's no input of blanket fuel, there's no problem, but no new core fuel can be created by the blanket fuel recycling loop, and so you'll run out of core fuel. If you use up the core fuel you can make more using the chemical plant recipe. But if the output of depleted core fuel backs up there's nothing to be done, you can't dump, store or remove that depleted core fuel from the reactor, you have to reprocess it, and that means you need access to the inputs and need to make sure that the core fuel produced has somewhere to go.

The second loop (for blanket fuel) is done in an enrichment plant. It takes in enriched blanket fuel in 15 unit batches and outputs three core fuel and 12 blanket fuel. There's no external ingredients required for this. Effectively, the blanket fuel is exposed to particles emitted by the reactor and some of it is converted to core fuel, enriched blanket fuel is that resulting mixture of blanket and core fuel, and the enrichment plant separates the two, sends the core fuel into the main reactor and returns the remainder for a second chance at being enriched. Since this loop (in combination with the other) produces more core fuel than the reactor needs to keep running, you must let this one back up. Make sure that the other loop from the reprocessing facility has priority for its returning core fuel.

Once you have created the first small batch of core fuel, which requires a lot of processing steps, you can use the reactor itself and the recycling loops to make all you need from the much easier to make blanket fuel, most of the complex steps in the nuclear chain become unneeded. You can use the slight surplus of core fuel generated by one reactor's loops to seed another so long as you can connect to it with a pipe.

Creating the starter core fuel

The reactor produces its own core fuel but you will need to make a bit to get started. It is produced in a Chemical Plant II from 20% enriched uranium and salt. You make 20% uranium by processing 4% uranium in an enrichment plant with more Hydrogen Fluoride, you can use a loop back and sorter to accomplish this.

Use a pipe balancer to make sure that the core fuel coming back from the two recycling loops is given priority over new core fuel otherwise the loop might back up.

Once the system is running you can pause this plant but be ready to use it to start up again. The only reason you'd need to is if you ran out of blanket fuel, this would cause the reactor to consume its core fuel supply and stop.

Creating input blanket fuel

Blanket fuel recycles through the loops but it diminishes as it's converted to core fuel, so you'll need a constant input of new blanket fuel. There are two sources, each of which has two possible recipies.

Using a Nuclear Reprocessing Facilty, you can make blanket fuel from either spent fuel or spent MOX, giving you a way to reuse the wastes from your older reactors. These can be belted in from the waste facilities where they are stored. There's no chance of backup as they're used in the same amounts, so feel free to share a belt for these. As before the byproduct is fission products, and you'll need inputs of salt, acid and molten glass (but surprisingly not steel, I guess since the waste comes in as a barrel the plant is just reusing the same barrel for the fission products). You will want to start out this way to get rid of your hazardous waste. It makes three a minute.

The second way is in a chemical plant, in which you combine either depleted uranium (which you probably have a lot of sitting around) or new yellowcake. A Chemical Plant II makes three a minute with no waste products, only requiring a supply of salt (also three a minute).

All blanket fuel formulas create three per minute, which is enough to keep up with a fully-loaded recycling loop and replace all the blanket fuel it consumes. As before use pipe balancers to make sure the recycled blanket fuel has priority over the new or else the loop could back up.

One reactor won't fully load the recycling loops, so only one of these methods is needed at a time, but I recommend first using up your hazardous spent fuel and MOX first to free up the storage, then switching to your depleted uranium stockpile and then back to yellowcake. Using up the waste you generated on the earlier reactors might take you a century or more.

Superheated steam - power generation and more

The FBR generates superheated steam, which has double the energy content of regular high steam.

To optimally use the steam, you should build a shaft with two super turbines, two high-pressure II, two low-pressure II, and four large generators all plumbed in series. That will consume 96 superheated steam and give back 96 depleted steam, and completely occupy the 72 MW torque limit of a single shaft, which yields 60 MW of electricity. Four such shafts deliver 240 MW. One large cooling tower can recover the steam from one shaft, so you'll want four of those as well.

If you recycle all the steam you'll need 24 new water per level per minute to make it up as the cooling tower can only recover 75%, that is 96 at full speed. If you send the depleted steam to a bank of vacuum desalinators instead of cooling towers you can consume all the steam of a full output power plant and get a net gain of 37.5% extra fresh water, but that will require 16 desalinators, using 64 workers and 6.4 MW of power and a lot of space. If instead you feed 12 superheated steam to two desalinators you'll net all the water you need to make up for the loss plus a surplus of 36 per minute, using only 800 KW and 8 workers. Keep in mind that if you use all your steam for power you'll have none for desalination, so your reactor could run dry if you're at the redline unless you use a pipe balancer to ensure that the desalination gets priority. Most of the groundwater aquifers can support 96 water a minute (that's two pumps) sustainably if you don't use it for anything else, more than that they'll deplete over time.

The hydrogen reformer also includes a new method of splitting water using superheated steam to make hydrogen and oxygen that uses less energy than electrolysis. Tapping into your superheated steam for these processes will mean you can't fully use all of it for power generation. It's far more flexible to use power to make superheated steam in electric boilers, but that incurs a small loss.
Also, superheated steam isn't compatible with the oil refining process, so if you had been tapping your old reactor for your refinery's steam you'll need to either tap in after the super pressure turbine or use an electric boiler instead.

[Allir]

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