Progression

Progression

Note

Design stage. This page describes planned mechanics from the design document. Not implemented yet — see Roadmap (eras arrive over milestones M2–M13; reactor tiers T0 at M4, T1 at M5, T2a at M9, T3/T4 at M15).

Prompt Critical has three progression ladders that run in parallel:

1. Industry eras I0–I4 — the whole industrial complex, from a coal mine to the nuclear fuel cycle.
2. Reactor tiers T0–T4 — which kinds of reactor you can build.
3. Automation levels A0–A5 — how you control the plant, from hand wheels to plant-wide optimization.

There are no research points or tech trees. Eras are unlocked by materials: you cannot build the next era without the products of the previous one. A blast furnace needs coke, a graphite reactor needs pitch and electricity, a centrifuge cascade needs fluoropolymers and steel. If materials are obtained differently (for example, traded on a server), the order can change.

Eras do not replace each other. A complex in era I4 still mines coal, refines oil and smelts steel, because everything else is made from them.

Industry eras (I0–I4)

Era	Name	Industries and key plants	Main products for later eras	Typical reactor tier	Wiki pages
I0	Coal and steam	coal mine (methane, roof support, drainage), coal preparation, coal-fired boiler, steam engine → Create shaft	coal, steam, first mechanisms	—	Coal-and-Metallurgy, Energy-Grid
I1	Steel and power	coke ovens (coke, gas, tar, pitch), blast furnace, converter, rolling mill, seamless pipe; synchronous generator, power lines, transformer; water treatment; air separation unit	steel and pipes, electricity, coke and pitch → graphite, O₂/N₂/Ar	T0 (Acheson graphite needs electricity and pitch)	Coal-and-Metallurgy, Energy-Grid
I2	Oil and gas	seismic survey, drilling, oil field, oil treatment, pipelines, refinery, gas processing plant; gas boilers, gas turbines	fuels (diesel, fuel oil), sulfur, helium, H₂S, dodecane, oils, petroleum coke	T1	Oil-and-Gas, Energy-Grid
I3	Chemistry	pyrolysis, polymers, fluoropolymers, chlor-alkali, steam methane reforming → H₂ and syngas, NH₃, ion-exchange resins, TBP; combined-cycle plants	H₂, Cl₂, NaOH, resins, PTFE, TBP, transistor-era electronics	T2a / T2b, T3	Petrochemistry, Nuclear-Fuel-Cycle
I4	Nuclear	enrichment, fuel assemblies, closed fuel cycle, isotopes, RTGs	baseload power, isotopes	T3, T4	Reactor-Physics, Nuclear-Fuel-Cycle, Isotopes-and-RTG

A quest route ("the route") in the in-game handbook walks you through the eras. Quests mark progress and suggest the next step, but never lock mechanics.

Reactor tiers (T0–T4)

Tier	Type (real prototype)	Fuel	Moderator / coolant	What it teaches
T0	Graphite pile (CP-1, X-10)	natural uranium metal	graphite / air	criticality, delayed neutrons, reactor period
T1	Channel-type uranium-graphite (AM-1, RBMK-like)	low-enriched UO₂ (≈1.8–2.4 %)	graphite / boiling H₂O	void coefficient of reactivity (it can be positive!), xenon
T2a	VVER / PWR	UO₂ 3–5 %	H₂O / pressurized H₂O	pressurizer, steam generator, boron control
T2b	BWR	UO₂ 2–4 %	H₂O / boiling H₂O	direct cycle, steam activity
T3	Heavy water (CANDU)	natural UO₂	D₂O	online refueling, tritium
T4 (post-release)	Sodium fast reactor (BN)	MOX / U-Pu	none / Na	plutonium breeding, sodium fires

Tiers are emergent. The simulation core does not know "reactor types": it computes physics from the lattice composition (fuel, moderator, coolant, absorbers) and the geometry of the multiblock you built. A "T2a" is simply what you get when you assemble enriched UO₂ fuel in a pressurized light-water lattice. See Reactor-Physics.

The first nuclear milestone is a T0 graphite pile: natural uranium from a simplified chain (ore → metal), graphite made from coke-oven electrodes in an Acheson furnace, a zip_rod_winch emergency rod, a neutron_detector and an analog gauge. You bring it to criticality by watching the reactor period, and the trip system drops the "zip" rod.

The full-size reference reactor (PR-300) is a deliberate megaproject: its first core needs about 82,500 SWU of enrichment, roughly 87 hours of operation of a 100-machine cascade. The calibrated starting T2a unit is ≈ 100 MW(t).

Automation ladder (A0–A5)

A parallel ladder of control tools. Each level is unlocked by instrumentation and electronics recipes (vacuum tubes, relays, transistors, circuit boards, integrated circuits).

Level	Real prototype	Tools	Where it runs
A0 Manual	hand wheels, local gauges	Create levers, local instrument_* blocks	—
A1 Relay logic	relay cabinets, 1930s–60s	relays, contacts, timers, stepping switches — as blocks in the world	pc-sim, per tick
A2 Analog computers	electronic controllers and analog computers, 1950s–70s	summer, integrator (with drift), multiplier, function generator	pc-sim, per tick
A3 PLC and SIS	IEC 61131-3 PLCs; safety logic solvers	plc_controller (LD, FBD, SFC, ST, function block library), sis_logic_solver (cause and effect matrix)	pc-sim, scan cycle
A4 DCS / SCADA	DCS + SCADA	CC: Tweaked, pcui, pcnet, telemetry, historian	CC threads
A5 Plant level	ISA-95 levels 3–4; APC/RTO	optimization, scheduling, Create logistics driven by Lua	CC threads

PI control is available without a computer: at A2 through analog blocks (with integrator drift) and at A3 through PLCs. See Automation-Platform, SCADA-and-HMI and CC-Tweaked-API.

Cross-industry products

Pillar P7 says no chain is closed on itself. The GDD keeps a single registry of products that cross industry boundaries, with common NeoForge c: tags for compatibility with other mods (no hard dependencies). Key flows:

Into the nuclear fuel cycle

Product	From	Used for
sulfur	gas plant (Claus unit)	sulfur_burner → sulfuric acid for uranium leaching; also synthetic rubber
coal_tar_pitch, graphite_electrode, petroleum_coke, needle_coke	coke ovens, refinery coking	electrodes and acheson_furnace → reactor graphite
helium	gas plant (extracted from natural gas)	filling fuel rods, cryogenics
diesel_fuel	refinery	emergency diesel generators of the nuclear plant
diluent_dodecane	hydrotreated kerosene (refinery); coke ovens as a fallback	TBP diluent for PUREX and refining
tbp	chemistry	tributyl phosphate solvent for PUREX
hydrogen	electrolysis, steam methane reforming, refinery reforming	fuel cycle chemistry, hydrotreating
hydrogen_sulfide	amine treating at the gas plant	Claus unit, gs_exchange_tower (heavy water production)
chlorine, sodium_hydroxide_solution	chlor-alkali	zirconium chlorinator, hydrometallurgy, PVC, water treatment
ptfe and other polymers	petrochemistry	UF₆ and HF service, seals, belts, cable insulation
ion_exchange_resin	petrochemistry	uranium hydrometallurgy, water treatment
oxygen, nitrogen, argon, liquid_nitrogen	air separation unit	converter, zirconium welding, cold traps, nitrogen purging
seamless_pipe, welded_pipe (with pipe_spec)	steel mill	reactor piping, drilling, pipelines
molten_slag	blast furnace	portland_cement for waste conditioning

Out of the nuclear and isotope industry

Product	From	Used for
sealed_source (with source_spec)	isotope production	reactor startup_source, Ir-192 gamma radiography of welds, Am-Be neutron well logging
doped_silicon_ingot → doped_silicon_wafer	neutron transmutation doping	integrated circuits (automation level A4+)
xlpe	cross-linking polyethylene by Co-60 irradiation	high-voltage cables (220+ kV voltage class)

Water, fuels and energy

Product	From	Used for
raw_water → demineralized_water → boiler_feedwater, cooling_water	water treatment	reactors, boilers, oil field
sales_gas (≥ 95 % CH₄)	gas plant	boilers, gas turbines, furnaces, methane reforming
mine_methane	coal mine degassing	boilers
coke_oven_gas, blast_furnace_gas	coke ovens, blast furnace	boilers
fuel_oil	refinery	boilers
lube_oil, transformer_oil	refinery	bearing lubrication, transformers
copper_wire, aluminium_ingot, platinum_ingot	non-ferrous metallurgy	grid, pt_rh_gauze catalyst, refinery catalysts
cobalt_ingot, iridium_ingot	metallurgy	Co-60 and Ir-192 targets

Typical path through the game

1. I0. Sink a coal mine, watch methane and ventilation, fire a coal boiler, drive a steam engine onto a Create shaft.
2. I1. Build coke ovens and a blast furnace, roll steel and pipes, synchronize a generator to the grid. Make graphite from pitch and electrodes; build and start a T0 pile. Relay logic (A1) and analog controllers (A2) appear.
3. I2. Explore, drill and produce oil and gas; refine them. Sulfur, helium and diesel become available. Build a T1 channel reactor with turbine and grid connection.
4. I3. Chemistry: polymers, chlor-alkali, hydrogen, TBP, ion-exchange resins, silicon. With them, the uranium chain up to enrichment and fuel assemblies, and a T2a PWR-type unit with pressurizer, steam generators and xenon dynamics. PLCs, SIS and SCADA (A3–A4).
5. I4. Close the fuel cycle: reprocessing, MOX, waste vitrification and disposal; isotopes and RTGs. Plant-level optimization (A5), economy and emissions trading push the switch to nuclear power.

See also

• Overview-and-Design-Pillars
• Coal-and-Metallurgy, Energy-Grid, Oil-and-Gas, Petrochemistry
• Reactor-Physics, Nuclear-Fuel-Cycle, Isotopes-and-RTG
• Automation-Platform, Player-Content
• Roadmap