Physical Transformation AtlasPTA
Pathway · p-7cf62d4e9b · demonstrated

PWR primary heat delivery

Nuclear binding-energy differenceNuclear fissionTemperature gradientAdvective heat transportHeat flowUseful heat

Fission heats pressurised primary water that reactor coolant pumps circulate to the steam generator, where its heat is delivered across the tube walls to the secondary circuit — thermal energy delivered at a useful temperature, consumed inside the PWR system rather than exported.

Member of Pressurised-water reactor steam plant as its primary-heat-loop — a system whose other members and handoffs carry what this route alone cannot.

Epistemic state of the route

known constituent relations
5 / 5 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
PWR primary heat delivery · commercial
composition maturity
K8 · commercial technology — Nuclear fission plant
recorded-pathway overlap
this route is the recorded pathway PWR primary heat delivery
auxiliaries off the route
  • external input · electrical · reactor coolant pumps — establishes flow:bulk-fluid-motion: electrically powered reactor coolant pumps circulate the pressurised primary water through the core and the steam generator; the loop's heat transport is forced, not buoyant
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 · 5 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 heat

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).

  • Carnot limit · formula-bound · hard, filtered out by its applicability
    η ≤ 1 − T_c/T_h for any heat engine between reservoirs at T_h and T_c

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→ Temperature gradientestablishedclaim record
    kinetic → thermal · loss to radiative
    • fragment and neutron kinetic energy thermalised in the fuel; the fuel runs hotter than the coolant
    refs [2] [3]
  3. 03
    Temperature gradient —drives→ Advective heat transportestablishedclaim record
    thermal → thermal
    • a bulk fluid flow connects the hotter and colder regions
    • for forced circulation the flow may be supplied by an external pump rather than generated by buoyancy
    refs [3] [4] [5]
  4. 04
    Advective heat transport —produces→ Heat flowestablishedclaim record
    thermal → thermal
    refs [3] [4]
  5. 05
    Heat flow —converts into→ Useful heatestablishedclaim record
    thermal → thermal
    • heat delivered at a temperature above the point of use
    refs [3]

Evidence for the complete composition · 1

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

Evidence for the constituent relations · 5

  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. Pressurized Water Reactors — how a typical commercial PWR works (2025)
    nrc.gov · www.nrc.gov/reactors/power/pwrs · record
  5. [5]
    U.S. Department of Energy. DOE Fundamentals Handbook: Thermodynamics, Heat Transfer, and Fluid Flow, Volume 2 of 3 (DOE-HDBK-1012/2-92) (1992)
    DOE-HDBK-1012/2-92, June 1992 · www.energy.gov/sites/default/files/2026-04/DOE-HDBK-1012-92_VOL2.pdf · record

Cite this route

Physical Transformation Atlas (2026). route p-7cf62d4e9b: PWR primary heat delivery. Dataset revision rbfbfcbb70e57 (hash of the canonical data). https://physical-transformation-atlas.wldud5192.workers.dev/path/7cf62d4e9b

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.