Nuclear binding-energy difference → Useful heat

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.07 · Nuclear binding-energy difference × Thermophotovoltaicfamily: ThermophotovoltaicD.20 × C.20 · Nuclear binding-energy difference × Photothermalfamily: Photothermal

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).

• Visible-band fraction of thermal emission · formula-bound · hard, filtered out by its applicability
  η_vis ≤ ∫₃₈₀ⁿᵐ⁷⁸⁰ⁿᵐ B_λ(λ, T) dλ / σT⁴ — the share of a thermal emitter's radiated power that Planck's distribution places in the visible band at the emitter temperature
• Landsberg limit · formula-bound · hard, filtered out by its applicability
  η ≤ 1 − (4/3)(T_c/T_s) + (1/3)(T_c/T_s)⁴ for conversion of blackbody radiation at T_s with a sink at T_c; 93.3 % at 6000 K / 300 K

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→ Thermal emissionestablishedclaim record

   thermal → radiative

   • a flame or a heated emitter radiating

   refs [5] [3]
4. 04
   Thermal emission —produces→ Photonsestablishedclaim record

   radiative → radiative

   refs [6] [3]
5. 05
   Photons —drives→ Photothermal absorptionestablishedclaim record

   radiative → thermal

   refs [3]
6. 06
   Photothermal absorption —produces→ Heat flowestablishedclaim record

   thermal → thermal

   refs [3]
7. 07
   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 · 0

No source on record for this exact composition. The sources below support the individual steps, not the route as a whole.

Evidence for the constituent relations · 6

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]
   A. LaPotin, et al.. Thermophotovoltaic efficiency of 40% (2022)

   Nature 604, 287–291 · doi:10.1038/s41586-022-04473-y · crossref ✓ 2026-09-19 · record
6. [6]
   P. T. Landsberg, G. Tonge. Thermodynamic energy conversion efficiencies (1980)

   Journal of Applied Physics 51, R1–R20 · doi:10.1063/1.328187 · crossref ✓ 2026-09-19 · record