Physical Transformation AtlasPTA
Pathway · p-dc7d860e03 · demonstrated

Boiling-water reactor direct-steam plant

Nuclear binding-energy differenceNuclear fissionHot gasWorking-fluid expansion (heat-engine cycle)Mechanical motionRotating-machine generator actionCharge carriersElectrical work

The reactor coolant itself boils in the vessel and its steam drives the main turbine-generator — the direct-cycle topology, distinct from the generic nuclear steam plant (fission establishes a temperature gradient a heat-engine cycle converts) and from the pressurised-water reactor, whose steam generator belongs to the system layer.

Epistemic state of the route

known constituent relations
7 / 7 established or replicated · weakest constituent established
constituent maturity floor
K4 · experimentally observed
search for this exact route
A recorded pathway or a reviewed search records a demonstration of this composition.
recorded pathway
Boiling-water reactor direct-steam plant · commercial
composition maturity
K8 · commercial technology — Boiling-water reactor plant
recorded-pathway overlap
this route is the recorded pathway Boiling-water reactor direct-steam plant
auxiliaries off the route
  • external input · electrical · condensate / feedwater pumping and cycle-pressure restoration — establishes thermodynamic:expansion-pressure-drop: turbine exhaust is condensed and pumped back to the reactor vessel; reactor-vessel steam is delivered to a lower-pressure turbine / condenser side; the NRC's generic description: the resulting water is pumped out of the condenser with a series of pumps, reheated, and pumped back to the reactor vessel; the core is cooled by water circulated using electrically powered pumps (spelled as an external electrical input, not recirculating work, because the generic description does not say whether a given unit's main feedwater pumps are turbine-driven or motor-driven — a named plant would settle it (the second reader's finding 7))
Loads the named implementation needs that no linear route carries (pass 36); a whole-cycle or net efficiency includes them, the enumerated route is the useful-output causal spine.
route-level evidence
1 source for the complete composition · 8 cited by the constituent steps
boundaries and interfaces
BOUNDARY compatible · no region transition

Explorematrix context · physics checks · steps · route evidence · constituent evidence · cite

Matrix context

D = disequilibrium row · C = coupling family column. A cell reads the state of the atlas for that pair.

D.20 × C.27 · Nuclear binding-energy difference × Nuclear heatfamily: Nuclear heatD.20 × C.08 · Nuclear binding-energy difference × Heat engine (thermomechanical)family: Heat engine (thermomechanical)D.20 × C.14 · Nuclear binding-energy difference × Electromagnetic inductionfamily: Electromagnetic induction

Typed bounds on this route

Every limit the atlas holds for this route, as constraint records: reached through bounded_by claims on the route's own entities. Hard bounds (an upper bound or a formula) decide the thermodynamic-bound check above; benchmarks, constitutive relations and resource limits are listed and never decisive. No prose limit exists anywhere (pass 42).

Steps

  1. 01
    Nuclear binding-energy difference —drives→ Nuclear fissionestablishedclaim record
    nuclear → kinetic · loss to radiative
    • for neutron-induced fission: a fissionable nuclide and an incident neutron in an energy range with non-zero fission cross-section
    • critical geometry is required only for a self-sustaining chain reaction; a moderator is reactor-design dependent
    About 200 MeV per event, almost all as fragment kinetic energy (Frisch 1939); thermalisation is a separate step.
    refs [1] [2]
  2. 02
    Nuclear fission —produces→ Hot gasestablishedclaim record
    kinetic → thermal · loss to radiative
    • fission heating produces a vapour or gas working fluid in a DIRECTLY heated, same-circuit configuration: the reactor coolant itself boils in the vessel and its steam goes to the turbine (a boiling-water reactor), or the fissioning or fission-heated gas is the working medium (a gas-core or fissioning-plasma reactor)
    • not a pressurised-water reactor: there fission heats a pressurised liquid whose heat crosses a steam generator into a separate secondary circuit — the heat exchanger, not the core, makes the turbine's steam, and that topology belongs to the system layer, never hidden inside this claim (pass 38)
    refs [3] [4]
  3. 03
    Hot gas —drives→ Working-fluid expansion (heat-engine cycle)establishedclaim record
    thermal → mechanical · loss to thermal
    • the hot gas expands through a turbine or against a piston from an upstream pressure to a lower downstream pressure
    gas · above ~700 K
    refs [3] [5]
  4. 04
    Working-fluid expansion (heat-engine cycle) —produces→ Mechanical motionestablishedclaim record
    mechanical → mechanical · loss to thermal
    refs [3]
  5. 05
    Mechanical motion —drives→ Rotating-machine generator actionestablishedclaim record
    mechanical → electrical · loss to thermal
    • a shaft turning a rotor inside a stator, or a magnet moved past a coil
    conductor required · magnetic field required
    refs [6] [5]
  6. 06
    Rotating-machine generator action —produces→ Charge carriersestablishedclaim record
    electrical → electrical · loss to thermal
    refs [6] [7]
  7. 07
    Charge carriers —converts into→ Electrical workestablishedclaim record
    electrical → electrical · loss to thermal
    • carriers driven through an external load at the potential difference the source maintains
    refs [8]

Evidence for the complete composition · 1

  1. [4]
    U.S. Nuclear Regulatory Commission. Boiling Water Reactors — how a typical commercial BWR works (2025)
    nrc.gov · www.nrc.gov/reactors/power/bwrs · record

Evidence for the constituent relations · 8

  1. [1]
    O. Hahn, F. Strassmann. Über den Nachweis und das Verhalten der bei der Bestrahlung des Urans mittels Neutronen entstehenden Erdalkalimetalle (1939)
    Naturwissenschaften 27, 11–15 · doi:10.1007/BF01488241 · crossref ✓ 2026-09-19 · record
  2. [2]
    O. R. Frisch. Physical evidence for the division of heavy nuclei under neutron bombardment (1939)
    Nature 143, 276 · doi:10.1038/143276a0 · crossref ✓ 2026-09-19 · record
  3. [3]
    A. Bejan. Advanced Engineering Thermodynamics (4th ed.) (2016)
    Wiley · doi:10.1002/9781119245964 · crossref ✓ 2026-09-19 · record
  4. [4]
    U.S. Nuclear Regulatory Commission. Boiling Water Reactors — how a typical commercial BWR works (2025)
    nrc.gov · www.nrc.gov/reactors/power/bwrs · record
  5. [5]
    S. L. Dixon, C. A. Hall. Fluid Mechanics and Thermodynamics of Turbomachinery (7th ed.) (2014)
    Butterworth-Heinemann · doi:10.1016/C2011-0-05059-7 · crossref ✓ 2026-09-19 · record
  6. [6]
    M. Faraday. Experimental researches in electricity (1832)
    Philosophical Transactions of the Royal Society 122, 125–162 · doi:10.1098/rstl.1832.0006 · crossref ✓ 2026-09-19 · record
  7. [7]
    L. D. Landau, E. M. Lifshitz, L. P. Pitaevskii. Electrodynamics of Continuous Media (Course of Theoretical Physics, Vol. 8, 2nd ed.) (1984)
    Pergamon · book, no DOI · record
  8. [8]
    N. W. Ashcroft, N. D. Mermin. Solid State Physics (1976)
    Holt, Rinehart and Winston · book, no DOI · record

Cite this route

Physical Transformation Atlas (2026). route p-dc7d860e03: Boiling-water reactor direct-steam plant. Dataset revision rbfbfcbb70e57 (hash of the canonical data). https://physical-transformation-atlas.wldud5192.workers.dev/path/dc7d860e03

Ids and matrix addresses are stable across revisions; the revision hash identifies the exact canonical files the record was compiled from and is meta.data_hash in every /api export. Reuse terms: see the license field in any export.