See Also: Power Grid
Parts of the Nuclear Generator
The nuclear reactor is the primary source of heat that the generator uses to make power. It is represented as a 7x7 grid of reactor rod ports, which engineers can insert fabricated reactor rods into. Gas flows into the reactor in order to absorb heat from a gas channel rod, which is in turn heated by nuclear fission reactions. The gas then flows out of the reactor and into a gas turbine, where that thermal energy is converted into electrical power. The reactor has a baseline gas capacity of 200 liters, which can be expanded by installing gas channel rods.
Four different types of reactor rods can be manufactured from the nuclear nano-fabricator: Fuel Rods, Control Rods, Heat Exchanger Rods, and Gas Channel rods. Each has a thermal cross-section and neutron cross-section stat, which represents how much to allow or restrict the passage of heat or neutrons.
Whenever a neutron enters the reactor grid location of an inserted rod, it has a chance to interact with that rod based on its density and neutron cross-section. Denser rods and rods with a larger cross-section are more likely to interact with a neutron. If the neutron fails to interact it will simply continue in the same direction as previously. Otherwise, it will do RNG checks influenced by the rod's stats in the following order, and perform the first reaction that passes the RNG check:
- Neutron-Stimulated Nuclear Reaction: Checks the rod's Neutron Radioactivity. If successful, a nuclear reaction occurs, releasing one to five neutrons in random directions at medium to high speeds and raising the rod's temperature by 50 degrees. This deletes the original neutron.
- Nuclear Reaction: Checks the rod's Radioactivity. If successful, a nuclear reaction occurs, releasing one to five neutrons in random directions at slow, medium, or high speeds and raising the rod's temperature by 25 degrees. This deletes the original neutron.
- Reflection: Checks the rod's Hardness. If successful, the neutron bounces back in the direction it came, plus or minus 45 degrees.
- Moderation: Occurs if all other reactions do not occur. This lowers the neutron's speed by one stage, or deletes it if the neutron was already at a slow speed. If the rod was a control rod, it always deletes the neutron, regardless of its speed.
Radioactive or neutron radioactive rods can also undergo spontaneous neutron emission by passing separate RNG checks. These checks are independent of both the neutron interaction checks and each other:
- Spontaneous Neutron Decay: Checks Neutron Radioactivity and Neutron Cross-Section. If successful, a nuclear reaction occurs, releasing one to three neutrons in random directions at high speeds and raising the rod's temperature by 20 degrees. This reduces the rod's neutron radioactivity by 0.01 and raises its radioactivity by 0.005.
- Spontaneous Decay: Checks Radioactivity and Neutron Cross-Section. If successful, a nuclear reaction occurs, releasing one to three neutrons in random directions at slow, medium, or high speeds and raising the rod's temperature by 10 degrees. This reduces the rod's radioactivity by 0.01 and raises its nuclear waste by 0.005.
Aside from neutrons, reactor rods can also move heat throughout the reactor grid. How rapidly a rod is able to transfer heat to or from cardinally adjacent rods is dependent on its Thermal Cross-Section and Thermal Conductivity. If any reactor rod is above 1700 degrees kelvin, it will begin to melt. Once melted, it will have its neutron cross-section set to 5.0 and its thermal cross-section set to 1.0, making it dramatically more nuclearly active and much more efficient at exchanging heat with adjacent rods. This will cause a rapid spike in temperature in the reactor, potentially leading to a total meltdown.
Handling hot reactor rods can cause major burns. Spacepeople have extremely robust skin capable of harmlessly withstanding up to 80 degree Celsius metal straight from a nuclear reactor. Beyond that point, however, those not wearing gloves (even fingerless gloves work, provided they're not made of a conductive material) will take up to 50 BURN to the arm holding the reactor rod every life cycle, which would be extremely lethal if not for the tendency to cause you to drop the rod by simply incinerating the arm right off. At truly excessive temperatures (400+ degrees Celsius), the rod will set you on fire outright regardless of if you're wearing gloves.
- Neutron Cross-Section: 1.0
- Thermal Cross-Section: 0.02
Fuel rods are intended to provide a source of neutrons from spontaneous decay and from interacting with existing neutrons. They are optimally constructed from materials with high Radioactivity and/or Neutron Radioactivity. In order to ensure that they get hit by neutrons more often, it is also good for them to have high Density.
- Neutron Cross-Section: 1.0
- Thermal Cross-Section: 0.01
Control rods are intended to control the flow of neutrons in the reactor. They are optimally constructed from materials with high Density in order to increase how often they interact with a passing neutron. If you want them to reflect neutrons more often instead of simply deleting them, high Hardness is also ideal. Control rods have the unique mechanic of being able to control their insertion level into the reactor. This defaults to 100% and is functionally a multiplier to the rod's neutron cross-section. MechComp signals can be used to automatically control the rod insertion level. Control rods also have the unique property of simply deleting neutrons instead of slowing them down during moderation, making them effective at reducing neutron leakage from the reactor. They will lose this property if melted, however.
Heat Exchanger Rod
- Neutron Cross-Section: 0.1
- Thermal Cross-Section: 0.4
Heat exchanger rods are intended to control the flow of heat in the reactor. They are optimally constructed from materials with high Thermal Conductivity. They have a high thermal cross section and a low neutron cross-section, meaning that they can effectively move heat from the fuel rods to the gas channel rods without significantly interfering with the fission process.
Gas Channel Rod
- Neutron Cross-Section: 0.5
- Thermal Cross-Section: 0.05
- Gas Thermal Cross-Section: 0.95
Gas Channel Rods are intended to transfer heat from themselves into the gas that flows through them. They are optimally constructed from materials with high Thermal Conductivity. Each gas channel rod has a volume of 100 liters, meaning that installing more will allow the reactor to process more gas at once. Gas channel rods transfer their own temperature into their contained gas based thermal conductivity and gas thermal cross section. If a gas channel rod is melted, its gas thermal cross-section is set to 0.1, making it dramatically worse at heating the gas that passes through it. This is usually a good thing, though, as any gas that passes through a melted gas channel rod is leaked directly into the station atmosphere.
Gas channel rods also have a unique interaction with neutrons when they contain plasma gas. Every 10 mol of plasma present in a gas channel represents an additional 1% chance for any passing neutron to interact with the gas. If a neutron does interact, 1 mol of plasma will be deleted and replaced by 10 mol of radioactive fallout gas. This gas has a much lower specific heat than plasma, meaning that it may reduce the efficiency of a nuclear reactor over a long period of time. Additionally, the interacting neutron will increase its speed by one stage and continue on its previous path.
The reactor grid itself also has temperature, and functionally has a 0.95 thermal cross section for interacting with the gas that flows through it.
The gas turbine is where the power actually gets made. It takes in hot gas from the reactor and outputs electricity and moderately colder gas back to the reactor. The turbine functions at peak efficiency when rotating at 600RPM, and is designed for much cooler temperatures than the TEG. If the temperature of the gas in the turbine ever exceeds 3000 kelvin, an emergency purge system will activate and the turbine's entire gas contents will be ejected into the station atmosphere. The turbine has two configurable settings, both of which can be adjusted manually or using MechComp signals: Flow Rate and Stator Load.
Flow rate is the amount of gas the turbine can process at once. In order to normalize pressure across the pipe network, it is generally advised to set the turbine's flow rate equal to the flow rate of the reactor (which can be determined using an atmospherics analyzer, or mathematically as the number of gas channel rods * 100 + 200). Lowering flow rate will create a bottleneck effect that increases pressure before the turbine and decreases pressure after the turbine, which may cause pipes to burst in extreme cases. Raising flow rate will decrease pressure in the entire pipe network, which can be used to prevent excessive pressure from rupturing the pipes.
Stator load basically represents how much thermal energy is required to spin the turbine. Higher stator load settings will increase power generation per revolution and decrease the rate of revolution. In order to maintain peak generator efficiency, it is advised to adjust stator load to keep the turbine RPM as close to 600 RPM as possible. Clever usage of MechComp devices can allow for automatically adjusting stator load to compensate for changing amounts of thermal energy entering the turbine.
Nuclear Waste Centrifuge
When a fuel rod undergoes spontaneous decay in the reactor, it becomes marginally less radioactive and builds up a tiny bit of nuclear waste. This means that fuel rods become less effective over time. However, you don't have to simply throw away old fuel rods. They can be inserted into a nuclear waste centrifuge in order to be extracted for plutonium metal, which is highly valuable as a nuclear fuel. In order to determine how much plutonium can be extracted from a rod, use a material analyzer on it and check the value of its "Fissile Isotopes" stat. One point of fissile isotopes means one that one bar of plutonium can be extracted from the rod. Any left-over fissile isotopes will be output as radioactive waste barrels, which can be reinserted later when enough has been collected to equal a full plutonium bar.
Basic Startup Procedure
The following startup guide details how to make the nuclear reactor produce enough power for the station. This setup is not optimal for maximum power generation, and instead prioritizes simplicity and stability.
- Connect the Plasma Tanks: Locate the gas injector ports and use a wrench to connect plasma tanks to them. Optionally, use a multitool and set their injector pumps to 15000kPa in order to inject the gas much faster. Since the reactor operates at much lower temperatures than the TEG (roughly equivalent to a furnace burn), you may safely use six or possibly even more plasma tanks without worrying about a pipe rupture.
- Fabricate Cerenkite Rods: There should be a storage rack or crate near the reactor with 6 cerenkite ores on it. Take these ores (a radsuit is recommended to avoid being irradiated) and insert them into a nuclear nano-fabricator. Use them to fabricate two cerenkite fuel rods.
- Insert the Fuel Rods: Insert the two fuel rods into slots (2,4) and (6,4), as shown. This will cause the reactor to begin heating up due to spontaneous decay. The reactor room may be irradiated from this point on, so a radsuit is recommended.
- Configure the Turbine: Now you need to configure the turbine settings. Interact with it and set its flow rate equal to 1000 liters (200 + 8 gas channel rods * 100) to make sure that the turbine is not a gas flow bottleneck. Set the stator load to a high number, such as 150000. The exact optimal stator load depends on how much gas was added to the reactor and how hot it is, so adjust accordingly to try to reach an RPM of 600.
- Set the SMES: The turbine should be producing power by this point, and so the SMES units will need to be configured to distribute the power. On some maps some of them may be a considerable distance from the generator, and so asking a knowledgeable AI to set them for you may be helpful.
- Radiation: When neutrons hit the edge of the reactor grid, they are emitted out into the station environment. These neutrons can hit objects or mobs, causing them to become radioactive. Depending on the neutron speed, they may penetrate multiple objects, causing radiation to leak out of the reactor room and become a threat to the station. Non-antag engineers should avoid this with generous usage of control rods or potentially building additional walls around the reactor.
- Heat: Reactor rods, the gas turbine, and the reactor grid all have maximum safe temperatures, and may fail after exceeding that temperature. The turbine has a maximum temperature of 3000 kelvin, above which an emergency failsafe will eject the contained gas into the station atmosphere. Reactor rods have a maximum temperature of 1700 kelvin, above which they will melt, causing them to become significantly more thermally conductive and nuclearly active. The reactor grid has a maximum temperature of 2000 kelvin, above which the reactor will suffer a catastrophic meltdown.
- Pressure: As the mol count and/or temperature of a pipe network increases, pressure will also increase. Pipes have a maximum pressure of 15000kPa, above which they may break and release their contents into the station atmosphere. Since the volume of the gas turbine is fully configurable, overpressure can be easily managed by simply raising the flow rate of the turbine.
Chernobyl 2: Electric Boogaloo
As the reactor temperature increases towards 2000 kelvin, indicator lights will start flashing ominous symbols and it will send increasingly urgent PDA messages to the engineering mail group. Should the temperature situation not be rectified before hitting 2000 kelvin, the reactor will melt down completely. This causes a massive explosion and additionally releases the reactor's gas contents, plus 6000 mol of radioactive fallout gas.
It goes without saying that this is extremely bad. Luckily, actually melting down the reactor requires some doing, so it isnt likely to happen during non-antag engineer gameplay. The most common cause of a nuclear meltdown is a runaway reaction from putting too many fuel rods too close together in the reactor. The neutrons emitted by the fuel rods will cause more nuclear reactions in other fuel rods, potentially leading to exponential growth if fuel rods are not removed or control rods are not inserted to moderate the reactions.
Neutrons can be thought of as a ball of radiation that ping-pongs about in the reactor grid before either escaping or being brought to a halt by moderation from reactor rods. Nuclear reactions occurring inside the reactor release neutrons, which can travel in 8 directions from their source. Regardless of velocity, neutrons will travel one grid square at a time and roll an RNG chance based on rod density and neutron cross section to interact with any reactor rod that they happen to occupy the same grid space as. For more info on neutron interactions with reactor rods, see Reactor Rods.
Neutrons can be assigned three different velocities upon creation: slow, medium, and fast. Being moderated by a reactor rod will downgrade the neutron's velocity by one stage, except for control rods which will immediately stop the neutron (deleting it). Neutrons are also deleted when they cause a nuclear reaction. When a neutron interacts with plasma gas, the velocity of the neutron will instead be increased, allowing it to exist longer before being moderated to a halt.
When a neutron hits the edge of the reactor grid, it is released into the station atmosphere. Here, neutrons function as invisible projectiles. They can pass through or interact with objects similarily to how they would in a nuclear reactor, and higher velocity neutrons will be able to interact with more objects before coming to a halt. Neutron interactions outside the reactor grid will cause the affected object to become radioactive, which is visible as a distinct green glow.
The Ideal Gas Law
Disclaimer: None of this physics knowledge is required in order to be an effective engineer, but it may help you to understand why certain things about gasses are true and how you may more effectively manipulate the reactor in your favor.
Gasses in Space Station 13 roughly obey the ideal gas law, which is a physics equation detailing the behavior of an "ideal" gas: that is, one composed of volumeless particles that do not interact with each other. The ideal gas law is defined as:
Pressure * Volume = Mol Count * the Ideal Gas Constant * Temperature
More simply put, PV = nRT. A further breakdown of each of these values:
- Pressure (P): This is the force that the gas exerts on its surroundings, measured in pascals. Atmospheric pressure is 101.325 kilopascals, and a pressurized gas canister may be well over 4,000 kilopascals. The reactor operates at fairly low temperatures, so you don't have to worry too much about pressure. Above 15,000 kilopascals, the pipes have a chance to burst, releasing dangerous burning plasma and nuclear fallout. If pressure does get too high, increasing the flow rate of the gas turbine can control it by raising the total volume of the pipe network.
- Volume (V): This is the amount of space that the gas occupies, measured in liters. The main method of changing this for the pipe network is by changing the flow rate of the gas turbine. Adding gas channels to the reactor will also increase its volume by 100 liters per channel.
- Mol Count (n): A mole is a specific number of things, in this case gas particles. Adding more gas to the pipe network increases its mol count. This increases the amount of thermal energy that can be transferred from the reactor and to the gas turbine, allowing for higher power output. Raising mol count will also raise pressure, so adjust accordingly.
- The Ideal Gas Constant (R): A constant multiplier that is a part of the ideal gas formula. This is a physics constant, and so nothing can be done to change it. It is equal to 8.31446261815324.
- Temperature (T): The average thermal energy of the gas, measured in kelvins. Aside from raising mol count, raising temperature is the other main way to transfer more energy into the gas turbine to make electrical power. Nuclear reactions create heat in the reactor, which will cause it to raise the temperature of gas that flows through it. The gas turbine lowers the temperature of gas that flows through it by converting some thermal energy into electrical energy.
Applying these laws of physics to the reactor, you can see that the total thermal energy of a given volume of gas would increase when its mol count and/or temperature increases. Therefore, adding a large number of gas channel rods to the reactor in order to allow for greater gas flow will likely improve power output. Running at a higher temperature will also increase output, though one has to be mindful of the temperature limits of the various reactor components.
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