Fission Reactor: Difference between revisions

 
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[[File:Fission reactor.png|thumb|right]]
[[File:Fission reactor.png|thumb|right]]


This page is a work in progress! Many essential things are missing.  
A '''Fission Reactor''' is a multiblock structure that generates massive amounts of heat but does not produce power on its own. How much heat is generated depends on the rate at which it burns [[Fissile Fuel]]. The only way to transform this heat into power is to inject "fresh" coolant into the reactor and use the heated coolant that comes out to generate power. With water cooled reactors, power is generated by directly piping steam into an [[Industrial Turbine]]. Sodium cooled reactors use a [[Thermoelectric Boiler]] as a heat-exchanger to cool down the [[Superheated sodium]] and heat up water into [[Steam]] that is in turn sent to an [[Industrial Turbine]].


The '''Fission Reactor''' is a multiblock structure that allows for variable input rates of [[Fissile Fuel]]. The reactor uses either [[Sodium]] or water as a coolant. Power is generated by converting the generated heat into power in an [[Industrial Turbine]]. With water cooled reactors, this is done by directly piping steam into an [[Industrial Turbine]]. Sodium cooled reactors use a [[Thermoelectric Boiler]] as a heat-exchanger to cool down the [[Superheated sodium]] and heat up water into [[Steam]].
Fission reactors need special care: even at very low burn rates, they generate heat faster than they can dissipate it to the environment. The biggest problem most players will face will be to maintain a steady flow of coolant.
 
'''For more tips and tutorials, see the [[Fission Reactor Tutorial]] page.'''
 
'''Note: You must have Mekanism: Generators installed to have the fission reactor in your game. Without generators, there is no way to obtain [[Polonium Pellet|polonium]] using only base Mekanism.'''


== Construction ==
== Construction ==


* The structure must be a cuboid of minimum size 3x4x3 (along X, Y and Z), up to 18x18x18.
* The structure must be a cuboid of minimum outside size 3x4x3 (along X, Y and Z), up to 18x18x18.
* The edges of the outer shell must be made of [[Fission Reactor Casing]]
* The edges of the outer shell must be made of [[Fission Reactor Casing]]
* The faces of the outer shell can be either [[Fission Reactor Casing]], [[Reactor Glass]], [[Fission Reactor Port]] or [[Fission Reactor Logic Adapter]]
* The faces of the outer shell can be either [[Fission Reactor Casing]], [[Reactor Glass]], [[Fission Reactor Port]] or [[Fission Reactor Logic Adapter]]
* The interior of the cube can be either air or fission control rods:
* The interior of the cube can be either air or fission control rods:
** A control rod is formed by a 1x1 block wide column made of 1 to 15 [[Fission Fuel Assembly]] and a single [[Control Assembly]] at the top
** A control rod is formed by a 1x1 block wide column made of 1 to 15 [[Fission Fuel Assembly]] and a single [[Control Rod Assembly]] at the top
** Control rods must not touch each other. Maximum control rod density can be achieved by placing them in a checkerboard pattern.
** Control rods should not touch each other. Optimal control rod density can be achieved by placing them in a checkerboard pattern. Cooling is penaltized if control rods touch each other.
 
 
Some example control rod setups as seen from the top ( is for [[Fission Reactor Casing]] or [[Reactor Glass]], R is for a control rod):
 
        CCCCC  CCCCC
  CCC  C  C  CR RC
  CRC  CR RC  C R C
  CCC  C  C  CR RC
        CCCCC  CCCCC
 


A fission reactor requires at least 4 [[Fission Reactor Port]]s:
A fission reactor requires at least 4 [[Fission Reactor Port]]s:
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* One waste output
* One waste output


 
Output ports must be configured to the proper output type by crouching and right-clicking them with a [[Configurator]] set to any of the configure modes.
Output ports must be configured to the proper output type by crouching and right-clicking them with a [[Configurator]].


== Reactor GUI ==
== Reactor GUI ==
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The burn rate is the rate at which the reactor will burn [[Fissile Fuel]]. For a newly formed reactor, it is automatically set to 0.1 mB/t. It can be changed in the reactor's statistics tab.
The burn rate is the rate at which the reactor will burn [[Fissile Fuel]]. For a newly formed reactor, it is automatically set to 0.1 mB/t. It can be changed in the reactor's statistics tab.


The theoretical maximum burn rate is 1 mB/t per [[[[Fission Fuel Assembly]] in the reactor, but the effective maximum burn rate depends on a number of factors (see [[#Safe operation]]).
The maximum burn rate is 1 mB/t per [[Fission Fuel Assembly]] in the reactor, but the safe maximum burn rate depends on a number of factors (see [[Fission Reactor Tutorial]]).


=== Heating Rate ===
=== Heating Rate ===


The heating rate represents how much coolant is heated up per tick. The actual value depends on the burn rate. For a burn rate of one 1 mB/t, the heating rate is:
The heating rate represents how much coolant is heated up per tick. The actual value depends on the burn rate. For a burn rate of one 1 mB/t, the heating rate is:
* 20000 mB/t for a water cooled reactor
* 20,000 mB/t for a water cooled reactor
* 200000 mB/t for a sodium cooled reactor
* 200,000 mB/t for a sodium cooled reactor




For safe operation, the external cooling setup must be able to handle that much heated coolant per tick. See the [[#Safe Operation|relevant section]].
For safe operation, the external cooling setup must be able to handle that much heated coolant per tick.


=== Temperature ===
=== Temperature ===


The core's temperature: green OK, yellow: danger zone, red: imminent meltdown.
The core's temperature:  
 
* green (< 600K)
TODO: add actual figures.
* yellow (>600K <1000K)
* orange (>1000K <1200K)
* red (>1200K): the reactor will take structural damage beyond this point.


=== Damage ===
=== Damage ===


This indicates the actual structural damage of the reactor. When a reactor reaches critical temperature, it will start taking damage and this value will go up. The damage value of a reactor that has overheated but been stopped on time to prevent a meltdown will slowly go down on its own, no player intervention is needed.
This indicates the actual structural damage of the reactor. When a reactor reaches critical temperature, it will start taking damage and this value will go up. The damage value of a reactor that has overheated but been stopped on time to prevent a meltdown will slowly go down on its own, no player intervention is needed.
TODO: need more tech details: how fast is damage recovery? does it recover if running in the danger zone (yellow heat value), etc.


== Cooling and power production ==
== Cooling and power production ==


Cooling a fission rector and converting the generated heat into power can be done in two ways: water cooling and sodium based cooling.
Cooling a fission reactor and converting the generated heat into power can be done in two ways: water cooling and sodium based cooling. Regardless of the cooling solution, an [[Industrial Turbine]] will be the actual power generator.
 
"Things to know" about how pipes/tubes work in Mekanism (to be moved into its own page):
 
* The pump rate is the rate at which the pipe can pump gases/fluids from a container when set in pull mode
* The capacity is how much the single pipe adds to to the pipe network's capacity (a pipe network being all pipes connected together)
* At each tick, a pipe network tries to dump its whole buffer (i.e. up to the networks' capacity) evenly among all connected receivers
* In effect, with no pipes set to pull mode, the actual transfer rate is limited by the minimum value of the providers ejection rate into the network and the network's capacity
* If the ejection rate of a provider is lower than the pipe's rate, setting the pipe to pull mode will override the provider's ejection rate
 
 
=== Water based cooling ===
 
[[File:Minimal fission reactor.png|thumb|right|Minimal water cooled fission reactor]]
Water based cooling is sufficient for small setups, i.e. reactors with less than 20 [[Fission Fuel Assembly]] and a max burn rate of 20 mB/t. Beyond that, it gets hard to keep the temperature of the reactor core within acceptable parameters.
 
==== Setup ====
 
* pipe water into a [[Fission Rector Port]] configured as input only
* Connect a [[Fission Reactor Port]] configured as coolant output to the steam input valve of an [[Industrial Turbine]].
* Connect a [[Mechanical Pipe]] from one of the [[Industrial Turbine]]'s vents back to the coolant input of the reactor (or back to the same same mechanical pipe network from the first step).
 
 
'''Important''': the [[Industrial Turbine]] must have [[Saturating Condenser]]s in order to be able to condense steam into water and pipe that water back to the reactor. The max water output from a turbine can be seen in its statistics tab. The actual value is 64000 mB of water per condenser. Condensers must be placed at the same level as the [[Electromagnetic Coil]]s or above them (a single coil is sufficient for 4 blades, so this leaves plenty of room at the same level).
 
A water cooled reactor has a heat rate of 20000 mB of water for 1 mB of [[Fissile Fuel]] burnt.
 
==== Sample build ====
 
The picture to the right shows a minimal fission reactor setup. From left to right: [[Induction Matrix]], [[Industrial Turbine]], Fission Reactor. The reactor has a single [[Fission Fuel Assembly]]. It takes [[Fissile Fuel]] from its front input port, [[Nuclear Waste]] is output to the right to a [[Nuclear Waste Barrel]]. In the back behind the reactor, there are two [[Electric Pump]]s feeding the coolant loop with fresh water if need be. The [[Industrial Turbine]] is a minimal 5x9x5. This setup generates 71.4 kJ/t when burning [[Fissile Fuel]] at its maximum of 1 mB/t. That's roughly 2.5 times less power than a [[Gas-Burning Generator]] burning [[Ethylene]].
 
=== Sodium based cooling ===


[[File:Sodium cooled reactor.png|thumb|right|Sodium cooled fission reactor]]
'''Important''' (this applies to both cooling solutions):
[[File:Sodium cooled reactor (back).png|thumb|right|Boiler - Turbine piping]]
* the [[Industrial Turbine]] must have [[Saturating Condenser]]s in order to be able to condense steam into water and pipe that water back to the reactor cooling loop. The max water output from a turbine can be seen in its statistics tab. The actual value is 64000 mB of water per condenser. Condensers must be placed above the [[Rotational Complex]].
* the turbine has an internal energy buffer that will slowly (more or less) fill up. Once full, it will only consume as much steam is needed to provide power to external consumers. As a result, its steam tank will start to fill up if the reactor generates steam faster than the turbine consumes it, less coolant will flow back to the reactor, resulting in less and less fresh coolant in the reactor's coolant tank. The reactor will start to eat up coolant, until meltdown.  


For larger reactors, with a burn rate higher than 20 mB/t, [[Sodium]] is a much more efficient coolant and allows very high burn rates at lower core temperatures. [[Sodium]] based cooling requires a [[Thermoelectric Boiler]] as an intermediate heat-exchanger to cool down the [[Superheated sodium]] from the reactor and heat up water into [[Steam]].
== [[Radiation]] and nuclear waste handling ==


The [[Thermoelectric Boiler]] has been updated in Makanism v10 to make it use heated coolant as a heat source. The [[Boiler Valve]]s can be configured with a [[Configurator]] (crouch + right click) to make them input only, output steam or output coolant.
As a byproduct of burning [[Fissile Fuel]], fission reactors produce [[Nuclear Waste]] which can be converted in [[Polonium Pellet]]s, [[Plutonium Pellet]]s or [[Antimatter Pellet]]s. The first two produce [[Spent Nuclear Waste]] as a byproduct (at a ratio of 1:10), while [[Antimatter]] production is a completely clean process (i.e. no radioactive byproducts).


==== Setup ====
Nuclear Waste can also be made into reprocessed fuel fragments, which allows for 80% of used fuel to be recovered. Note that looping this process '''does not yield infinite fuel.''' ''However'', it is highly efficient, allowing you to burn the same amount of fuel nearly 5 times longer.  
 
Setup a [[Thermoelectric Boiler]] + [[Industrial Turbine]] as described on the boiler page with the exception that in step 7, you will need two [[Boiler valve]]s on a steam catch or steam cavity layer, one for steam output, the other for coolant output.
 
It is important to build the boiler with water cavity layers (step 3c of the boiler's setup) in order to have a decent enough water + heated coolant storage capacity.
 
Next, connect the the boiler steam output (at or above the steam catch layer) to the turbine steam input, and pipe water back from one of the turbine's vents to one of the boiler's inputs at the heater or water cavity layers.
 
Setup fully some fully upgraded [[Electric Pump]]s (1 KJ/t for 1000 mB of water per tick) to inject fresh water in the water-steam loop. It is necessary to keep them running in order to keep the boiler's water tank full when running at high heat rates (compared to what the boiler can support). How many pumps are required is left to the reader to experiment with (see [[#Safe Operation]]).
 
Finally, connect the reactor's heated coolant output to one of the boiler's inputs at the heater or water cavity layers, and the boiler's coolant output to one of the reactor's inputs. While the boiler's valves must be placed in the proper layers. the placement of the reactor's ports does not matter.
 
==== Sample build ====
 
The picture to the right shows a 5x9x5 sodium cooled fission reactor, backed by a fairly small 5x7x5 [[Thermoelectric Boiler]] and a 7x13x7 turbine with 18 blades. It produces 3.85 MJ/t (1.54 MFE/t, 385.63 kEU/t) at peak burn rate (30 mB/t). Note that this same turbine could work with a reactor twice that size, but the boiler would need to be extended. On the right side of the reactor there is a crude, yet effective breaker-switch system (see [[#Safe Operation]]).
 
The second picture shows the boiler and turbine piping as well as a single pump (which is not enough for this configuration).
 
== Safe operation ==
 
The worst thing that can happen is a core meltdown, which in Mekanism results in a big explosion. Big. Really big. Followed by lethal radiations over a 5 chunks radius (that's 80 blocks) that will last for several in-game weeks.
 
A few rules of thumb:
 
* In order to avoid chunk loading related glitches, do not build a fission reactor, [[Thermoelectric Boiler]] or [[Industrial Turbine]] on a chunk boundary.
* Keep all chunks involved in fission power generation and waste recycling loaded (use an [[Anchor Upgrade]] in [[Teleporter]]s or [[Quantum Entangloporter]]s).
* For good measure, even if a tube or pipe just crosses a chunk, keep it loaded.
* Always start with low burn rates (the default 0.1 mB/t is good!) and increase it in small steps.
 
=== Circuit Breaker ===
 
Every reactor should have a circuit breaker that will, in many cases, prevent accidental meltdown or waste leaks.
 
Any form of RS-latch can be used for this purpose, with the SET signal wired to reactor critical conditions and Q output to reactor activation.
 
The pictures below show a crude yet effective circuit breaker setup. Despite its rudimentary look, it is impervious to destruction by water or lava spills.
<gallery>
Circuit breaker-on.png|Switched on
Circuit breaker-tripped.png|Tripped
Circuit breaker-layout.png|Logic adapter layout
</gallery>
 
All pistons are regular, NON-sticky pistons. The two honey blocks can be replaced by slime blocks, which ever is the easiest to acquire.  
 
The rightmost picture shows the [[Fission Reactor Logic Adapter]] layout. The two on the top right are set to signal on excessive heat and waste tank full. The bottom center one is set on "activation".
 
When building it, the reactor's burn rate should be set to 0, so that when the redstone block is placed, the reactor will activate but not burn anything.
 
A button should be placed on the back of the leftmost piston to switch the circuit breaker back on whenever it gets tripped.
 
The reactor should never be activated if the circuit breaker is in the tripped position: even with an adapter set to "activation" nothing will prevent the player from forcibly activating the reactor from its GUI; from this point any critical condition will not trip an already tripped circuit breaker and cause a meltdown. Failing to follow this rule may result in a false feeling of safety. In order to prevent this, note the presence of an [[Industrial Alarm]] on the bottom left. It should be triggered by the restone block when the circuit breaker is tripped. Its main use is to annoy player until he turns the breaker back on.
 
Here is the basic procedure to follow when the circuit breaker is tripped by a critical condition:
 
* Set the reactor burn rate to 0
* Switch the circuit breaker back on (this will activate the reactor but this is safe since it won't burn fuel). The annoying alarm is now gone.
* Fix whatever caused the problem
 
 
'''DISCLAIMER:''' A circuit breaker will not help in all situations. In case of reactor overheating with a large reactor and burn rate and critical coolant shortage, the temperature will have reached over 1400K before tripping the breaker. Without a quick injection of new coolant, the reactor will not cool down quickly enough and will keep taking structural damage until the unthinkable happens.
 
=== Avoiding bottlenecks ===
 
Bottlenecks in the cooling chain are what limits the actual burn rate of a reactor.
 
To be continued...
 
== Radiation and nuclear waste handling ==
 
As a byproduct of burning [[Fissile Fuel]], fission reactors produce [[Nuclear Waste]] which can be converted in either [[Polonium Pellet]] or [[Plutonium Pellet]]. Both conversion paths produce [[Spent Nuclear Waste]] as a byproduct (at a ratio of 10:1), which must be stored in [[Radioactive Waste Barrels]]. [[Nuclear Waste]] or [[Spent Nuclear Waste]] can be piped into a [[Nuclear Waste Barrel]] from its top or bottom side with a [[Pressurized Tube]].
 
* [[Nuclear Waste]] is radioactive.
* All products and intermediate products of converting [[Uranium Ore]] to [[Fissile Fuel]] are not radioactive, i.e. safe to handle.
* Intermediate products and byproducts of recycling [[Nuclear Waste]] are radioactive: [[Polonium]], [[Plutonium]] and [[Spent Nuclear Waste]].
* [[Plutonium Pellet]]s and [[Polonium Pellet]]s are not radioactive.


If a material is radioactive, it will be noted in a specially colored tooltip.


Radiation can leak into the environment for the following reasons:
Radiation can leak into the environment for the following reasons:
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* Fission reactor overheating leading to a core meltdown (actually blowing up).
* Fission reactor overheating leading to a core meltdown (actually blowing up).
* Fission reactor running with its waste tank full.
* Fission reactor running with its waste tank full.
* Breaking any block containing radioactive materials. Most notably [[Pressurized Tube]]s and [[Radioactive Waste Barrel]]s, but also any machine (like a [[Pressurized Reaction Chamber]] containing radioactive materials. These can still be broken safely if they are somehow drained of their radioactive contents beforehand.
* Breaking any block containing radioactive materials. Most notably [[Pressurized Tube]]s and [[Radioactive Waste Barrel]]s. This also applies to machines, like a [[Pressurized Reaction Chamber]] containing polonium for example. These can still be broken safely if they are somehow drained of their radioactive contents beforehand.
 
Radioactive materials can be stored in [[Radioactive Waste Barrel]]s (insert the material from its top or bottom side with a [[Pressurized Tube]]. [[Radioactive Waste Barrel]]s delete their contents at a rate of 1 mB per minute, and are the recommended storage container for waste. Check its page for more information.


[[Quantum Entangloporter]]s cannot handle radioactive materials. As a result, it is not possible to make [[Polonium Pellet]]s with a reactor in the nether (since the [[Solar Neutron Activator]], which is required to produce [[Polonium]] from [[Nuclear Waste]] needs direct sunlight) or have a reactor in the overworld and store waste in the nether.
[[Quantum Entangloporter]]s cannot handle radioactive materials. As a result, it is not possible to make [[Polonium Pellet]]s with a reactor in the nether (since the [[Solar Neutron Activator]], which is required to produce [[Polonium]] from [[Nuclear Waste]] needs direct sunlight) or have a reactor in the overworld and store waste in the nether.


==Detailed Damage/Meltdown Mechanics==
A reactor starts sustaining damage when its temperature is over 1200K. The formula for damage taken per tick is '''min(currentTemp, 1800) / 12 000''' in percentage. This means that at 1200K, the reactor sustains 2% damage per second, and any temperature over 1800K is treated as 1800K (and damages the reactor at 3% per second).


=== Nuclear Waste Barrels ===
If temperature falls under 1200K, the reactor repairs itself at a rate of '''(1200 - currentTemp) / 120 000''' per tick in percentage. This means that the fastest you can repair a reactor is 0.2% per second.
 
TODO: move this to its own page


Waste Barrels are used to store (or as buffer for) [[Nuclear Waste]] and [[Spent Nuclear Waste]]. They delete their contents at a rate of 1 mB per minute.  
While damage is over 100% and the temperature is above 1200K, the reactor rolls a chance to meltdown every tick. The precise chance is calculated as '''damage / 1 000''' (unit is in percentage) every tick. For example, at 100% damage the meltdown chance per tick would be 0.1%, while at 100 000% damage the chance would be 100%.
[[File:Fission meltdown safe.png|thumb|A graph showing the chance to reach a certain damage percentage before meltdown. The horizontal axis is damage percentage, the vertical axis is chance in percentage.]]


The player can check the storage status of [[Nuclear Waste Barrel]]s by crouching and right-clicking it with an empty hand. Green radiation particles start to appear as a barrel fills up (these are just a rough visual indicator of a barrel's fill ratio, not actual radiations).
== Tips & Trivia ==


Waste barrels cannot be moved by any means (pistons, cardboard box, etc.). Also because barrels containing any radioactive waste cannot be broken safely, the only way to safely move a non empty barrel it transfer its contents to another barrel before breaking it. This can be done by connecting a [[Pressurized Tube]] to its top or bottom side in pull mode.
* Experiment in a creative world! There are no consequences for failure, and you can use the following console commands, which are fairly self-explanatory in function:
 
Even if Waste Barrels are blast resistant, but pressurized tubes carrying waste to them are not. As a rule of thumb, do not allow creepers wandering around a fission reactor or waste transformation or disposal units.
 
== Tips ==
 
* For any given reactor burn rate, the more turbine blades, the more energy is produced per mB of [[Fissile Fuel]]. As a result,  the bigger the turbine the better. Also it is best to max out the rotor height and make trade-offs on the vents/condensers count. With a slightly shorter rotor, one could add more condensers and achieve higher burn rates and total power produced, but at a higher cost in terms of power produced per mB of [[Fissile Fuel]] burnt.
* Experiment in a creative world! There, you can experiment with the console commands (the last one is just in case things go wrong, but don't be a chicken and abuse it!):
   /mek build fission
   /mek build fission
   /mek build remove
   /mek build remove
   /mek radiation removeAll
   /mek radiation removeAll
* A complete removal of every block constituting a reactor will also remove the associated multiblock data. This is applicable to all multiblocks in Mekanism, but only has notable use for a fission reactor.
** Notably, this allows the player to reset structural damage by mining the entire reactor and replacing it. This can be an unintended and tedious way to save a reactor from melting down.
** As it counts as a new multiblock, this also voids any nuclear waste stored inside without releasing radiation into the environment. Beware that voiding nuclear waste like this has been confirmed to be a bug, and might be fixed in the future.
* Theoretically, with the best possible luck, a critical reactor (starting from 0% damage and high temperature) can survive at most 9 hours, 15 minutes and 33 seconds. However, practically the reactor will explode much sooner, since the meltdown chance increases with time and is rolled 20 times a second.
** To reach this point, you must survive 666 666 rolls, each with an increasingly small chance of survival.
** The chance to reach this theoretical best is so small it is difficult to comprehend: an estimation yields 10^-1 600 000, or 1 in 10...0 with 1.6 million zeroes inbetween. For comparison, there are only 10^82 atoms in the universe.
[[Category:Generators]]
{{Mekanism}}

Latest revision as of 07:07, 13 March 2024

Fission reactor.png

A Fission Reactor is a multiblock structure that generates massive amounts of heat but does not produce power on its own. How much heat is generated depends on the rate at which it burns Fissile Fuel. The only way to transform this heat into power is to inject "fresh" coolant into the reactor and use the heated coolant that comes out to generate power. With water cooled reactors, power is generated by directly piping steam into an Industrial Turbine. Sodium cooled reactors use a Thermoelectric Boiler as a heat-exchanger to cool down the Superheated sodium and heat up water into Steam that is in turn sent to an Industrial Turbine.

Fission reactors need special care: even at very low burn rates, they generate heat faster than they can dissipate it to the environment. The biggest problem most players will face will be to maintain a steady flow of coolant.

For more tips and tutorials, see the Fission Reactor Tutorial page.

Note: You must have Mekanism: Generators installed to have the fission reactor in your game. Without generators, there is no way to obtain polonium using only base Mekanism.

Construction

A fission reactor requires at least 4 Fission Reactor Ports:

  • One coolant input
  • One coolant output
  • One Fissile Fuel input
  • One waste output

Output ports must be configured to the proper output type by crouching and right-clicking them with a Configurator set to any of the configure modes.

Reactor GUI

Main fission reactor GUI

The reactor's GUI shows it's status, burn rate, heating rate, temperature and structural damage (health).

Status

The reactor's running status, either active or disabled.

To activate the reactor, either click the green activation button, or send a redstone signal to a Fission Reactor Logic Adapter configured in activation mode (just right click the Fission Reactor Logic Adapter block to configure it).

The reactor stops when a player clicks the red SCRAM button or if a redstone signal on a logic adapter goes from 1 to 0.

Burn Rate

Stats tab

The burn rate is the rate at which the reactor will burn Fissile Fuel. For a newly formed reactor, it is automatically set to 0.1 mB/t. It can be changed in the reactor's statistics tab.

The maximum burn rate is 1 mB/t per Fission Fuel Assembly in the reactor, but the safe maximum burn rate depends on a number of factors (see Fission Reactor Tutorial).

Heating Rate

The heating rate represents how much coolant is heated up per tick. The actual value depends on the burn rate. For a burn rate of one 1 mB/t, the heating rate is:

  • 20,000 mB/t for a water cooled reactor
  • 200,000 mB/t for a sodium cooled reactor


For safe operation, the external cooling setup must be able to handle that much heated coolant per tick.

Temperature

The core's temperature:

  • green (< 600K)
  • yellow (>600K <1000K)
  • orange (>1000K <1200K)
  • red (>1200K): the reactor will take structural damage beyond this point.

Damage

This indicates the actual structural damage of the reactor. When a reactor reaches critical temperature, it will start taking damage and this value will go up. The damage value of a reactor that has overheated but been stopped on time to prevent a meltdown will slowly go down on its own, no player intervention is needed.

Cooling and power production

Cooling a fission reactor and converting the generated heat into power can be done in two ways: water cooling and sodium based cooling. Regardless of the cooling solution, an Industrial Turbine will be the actual power generator.

Important (this applies to both cooling solutions):

  • the Industrial Turbine must have Saturating Condensers in order to be able to condense steam into water and pipe that water back to the reactor cooling loop. The max water output from a turbine can be seen in its statistics tab. The actual value is 64000 mB of water per condenser. Condensers must be placed above the Rotational Complex.
  • the turbine has an internal energy buffer that will slowly (more or less) fill up. Once full, it will only consume as much steam is needed to provide power to external consumers. As a result, its steam tank will start to fill up if the reactor generates steam faster than the turbine consumes it, less coolant will flow back to the reactor, resulting in less and less fresh coolant in the reactor's coolant tank. The reactor will start to eat up coolant, until meltdown.

Radiation and nuclear waste handling

As a byproduct of burning Fissile Fuel, fission reactors produce Nuclear Waste which can be converted in Polonium Pellets, Plutonium Pellets or Antimatter Pellets. The first two produce Spent Nuclear Waste as a byproduct (at a ratio of 1:10), while Antimatter production is a completely clean process (i.e. no radioactive byproducts).

Nuclear Waste can also be made into reprocessed fuel fragments, which allows for 80% of used fuel to be recovered. Note that looping this process does not yield infinite fuel. However, it is highly efficient, allowing you to burn the same amount of fuel nearly 5 times longer.

If a material is radioactive, it will be noted in a specially colored tooltip.

Radiation can leak into the environment for the following reasons:

  • Fission reactor overheating leading to a core meltdown (actually blowing up).
  • Fission reactor running with its waste tank full.
  • Breaking any block containing radioactive materials. Most notably Pressurized Tubes and Radioactive Waste Barrels. This also applies to machines, like a Pressurized Reaction Chamber containing polonium for example. These can still be broken safely if they are somehow drained of their radioactive contents beforehand.

Radioactive materials can be stored in Radioactive Waste Barrels (insert the material from its top or bottom side with a Pressurized Tube. Radioactive Waste Barrels delete their contents at a rate of 1 mB per minute, and are the recommended storage container for waste. Check its page for more information.

Quantum Entangloporters cannot handle radioactive materials. As a result, it is not possible to make Polonium Pellets with a reactor in the nether (since the Solar Neutron Activator, which is required to produce Polonium from Nuclear Waste needs direct sunlight) or have a reactor in the overworld and store waste in the nether.

Detailed Damage/Meltdown Mechanics

A reactor starts sustaining damage when its temperature is over 1200K. The formula for damage taken per tick is min(currentTemp, 1800) / 12 000 in percentage. This means that at 1200K, the reactor sustains 2% damage per second, and any temperature over 1800K is treated as 1800K (and damages the reactor at 3% per second).

If temperature falls under 1200K, the reactor repairs itself at a rate of (1200 - currentTemp) / 120 000 per tick in percentage. This means that the fastest you can repair a reactor is 0.2% per second.

While damage is over 100% and the temperature is above 1200K, the reactor rolls a chance to meltdown every tick. The precise chance is calculated as damage / 1 000 (unit is in percentage) every tick. For example, at 100% damage the meltdown chance per tick would be 0.1%, while at 100 000% damage the chance would be 100%.

A graph showing the chance to reach a certain damage percentage before meltdown. The horizontal axis is damage percentage, the vertical axis is chance in percentage.

Tips & Trivia

  • Experiment in a creative world! There are no consequences for failure, and you can use the following console commands, which are fairly self-explanatory in function:
 /mek build fission
 /mek build remove
 /mek radiation removeAll
  • A complete removal of every block constituting a reactor will also remove the associated multiblock data. This is applicable to all multiblocks in Mekanism, but only has notable use for a fission reactor.
    • Notably, this allows the player to reset structural damage by mining the entire reactor and replacing it. This can be an unintended and tedious way to save a reactor from melting down.
    • As it counts as a new multiblock, this also voids any nuclear waste stored inside without releasing radiation into the environment. Beware that voiding nuclear waste like this has been confirmed to be a bug, and might be fixed in the future.
  • Theoretically, with the best possible luck, a critical reactor (starting from 0% damage and high temperature) can survive at most 9 hours, 15 minutes and 33 seconds. However, practically the reactor will explode much sooner, since the meltdown chance increases with time and is rolled 20 times a second.
    • To reach this point, you must survive 666 666 rolls, each with an increasingly small chance of survival.
    • The chance to reach this theoretical best is so small it is difficult to comprehend: an estimation yields 10^-1 600 000, or 1 in 10...0 with 1.6 million zeroes inbetween. For comparison, there are only 10^82 atoms in the universe.


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