diff --git a/manual.md b/manual.md index 0b07fa0..1b8f1ed 100644 --- a/manual.md +++ b/manual.md @@ -1147,6 +1147,136 @@ an elevation of +30 or higher. It generates more at higher elevation, reaching maximum output at elevation +50 or higher. Its surroundings don't otherwise matter; it doesn't actually need to be in open air. +### nuclear generator ### + +The nuclear generator (nuclear reactor) is an HV power generator that +generates a large amount of energy from the controlled fission of +uranium-235. It must be fuelled, with uranium fuel rods, but consumes +the fuel quite slowly in relation to the rate at which it is likely to +be mined. The operation of a nuclear reactor poses radiological hazards +to which some thought must be given. Economically, the use of nuclear +power requires a high capital investment, and a secure infrastructure, +but rewards the investment well. + +Nuclear fuel is made from uranium. Natural uranium doesn't have a +sufficiently high proportion of U-235, so it must first be enriched +via centrifuge. Producing one unit of 3.5%-fissile uranium requires +the input of five units of 0.7%-fissile (natural) uranium, and produces +four units of 0.0%-fissile (fully depleted) uranium as a byproduct. +It takes five ingots of 3.5%-fissile uranium to make each fuel rod, and +six rods to fuel a reactor. It thus takes the input of the equivalent +of 150 ingots of natural uranium, which can be obtained from the mining +of 75 blocks of uranium ore, to make a full set of reactor fuel. + +The nuclear reactor is a large multi-block structure. Only one block in +the structure, the reactor core, is of a type that is truly specific to +the reactor; the rest of the structure consists of blocks that have mainly +non-nuclear uses. The reactor core is where all the generator-specific +action happens: it is where the fuel rods are inserted, and where the +power cable must connect to draw off the generated power. + +The reactor structure consists of concentric layers, each a cubical +shell, around the core. Immediately around the core is a layer of water, +representing the reactor coolant; water blocks may be either source blocks +or flowing blocks. Around that is a layer of stainless steel blocks, +representing the reactor pressure vessel, and around that a layer of +blast-resistant concrete blocks, representing a containment structure. +It is customary, though no longer mandatory, to surround this with a +layer of ordinary concrete blocks. The mandatory reactor structure +makes a 7×7×7 cube, and the full customary structure a +9×9×9 cube. + +The layers surrounding the core don't have to be absolutely complete. +Indeed, if they were complete, it would be impossible to cable the core to +a power network. The cable makes it necessary to have at least one block +missing from each surrounding layer. The water layer is only permitted +to have one water block missing of the 26 possible. The steel layer may +have up to two blocks missing of the 98 possible, and the blast-resistant +concrete layer may have up to two blocks missing of the 218 possible. +Thus it is possible to have not only a cable duct, but also a separate +inspection hole through the solid layers. The separate inspection hole +is of limited use: the cable duct can serve double duty. + +Once running, the reactor core is significantly radioactive. The layers +of reactor structure provide quite a lot of shielding, but not enough +to make the reactor safe to be around, in two respects. Firstly, the +shortest possible path from the core to a player outside the reactor +is sufficiently short, and has sufficiently little shielding material, +that it will damage the player. This only affects a player who is +extremely close to the reactor, and close to a face rather than a vertex. +The customary additional layer of ordinary concrete around the reactor +adds sufficient distance and shielding to negate this risk, but it can +also be addressed by just keeping extra distance (a little over two +meters of air). + +The second radiological hazard of a running reactor arises from shine +paths; that is, specific paths from the core that lack sufficient +shielding. The necessary cable duct, if straight, forms a perfect +shine path, because the cable itself has no radiation shielding effect. +Any secondary inspection hole also makes a shine path, along which the +only shielding material is the water of the reactor coolant. The shine +path aspect of the cable duct can be ameliorated by adding a kink in the +cable, but this still yields paths with reduced shielding. Ultimately, +shine paths must be managed either with specific shielding outside the +mandatory structure, or with additional no-go areas. + +The radioactivity of an operating reactor core makes starting up a reactor +hazardous, and can come as a surprise because the non-operating core +isn't radioactive at all. The radioactive damage is survivable, but it is +normally preferable to avoid it by some care around the startup sequence. +To start up, the reactor must have a full set of fuel inserted, have all +the mandatory structure around it, and be cabled to a switching station. +Only the fuel insertion requires direct access to the core, so irradiation +of the player can be avoided by making one of the other two criteria be +the last one satisfied. Completing the cabling to a switching station +is the easiest to do from a safe distance. + +Once running, the reactor will generate 100 kEU/s for a week (168 hours, +604800 seconds), a total of 6.048 GEU from one set of fuel. After the +week is up, it will stop generating and no longer be radioactive. It can +then be refuelled to run for another week. It is not really intended +to be possible to pause a running reactor, but actually disconnecting +it from a switching station will have the effect of pausing the week. +This will probably change in the future. A paused reactor is still +radioactive, just not generating electrical power. + +A running reactor can't be safely dismantled, and not only because +dismantling the reactor implies removing the shielding that makes +it safe to be close to the core. The mandatory parts of the reactor +structure are not just mandatory in order to start the reactor; they're +mandatory in order to keep it intact. If the structure around the core +gets damaged, and remains damaged, the core will eventually melt down. +How long there is before meltdown depends on the extent of the damage; +if only one mandatory block is missing, meltdown will follow in 100 +seconds. While the structure of a running reactor is in a damaged state, +heading towards meltdown, a siren built into the reactor core will sound. +If the structure is rectified, the siren will signal all-clear. If the +siren stops sounding without signalling all-clear, then it was stopped +by meltdown. + +If meltdown is imminent because of damaged reactor structure, digging the +reactor core is not a way to avert it. Digging the core of a running +reactor causes instant meltdown. The only way to dismantle a reactor +without causing meltdown is to start by waiting for it to finish the +week-long burning of its current set of fuel. Once a reactor is no longer +operating, it can be dismantled by ordinary means, with no special risks. + +Meltdown, if it occurs, destroys the reactor and poses a major +environmental hazard. The reactor core melts, becoming a hot, highly +radioactive liquid known as "corium". A single meltdown yields a single +corium source block, where the core used to be. Corium flows, and the +flowing corium is very destructive to whatever it comes into contact with. +Flowing corium also randomly solidifies into a radioactive solid called +"Chernobylite". The random solidification and random destruction of +solid blocks means that the flow of corium is constantly changing. +This combined with the severe radioactivity makes corium much more +challenging to deal with than lava. If a meltdown is left to its own +devices, it gets worse over time, as the corium works its way through +the reactor structure and starts to flow over a variety of paths. +It is best to tackle a meltdown quickly; the priority is to extinguish +the corium source block, normally by dropping gravel into it. Only the +most motivated should attempt to pick up the corium in a bucket. + administrative world anchor --------------------------- @@ -1208,8 +1338,6 @@ subjects missing from this manual This manual needs to be extended with sections on: -* power generators - * nuclear * powered tools * tool charging * battery and energy crystals