Transfers core decay heat to the steam generator while preserving the primary pressure boundary.
Public technical disclosure · Canadian patent application filed
Passive secondary-side
decay-heat rejection.
RMW-PDHRS-001 · PASSIVE SECONDARY-SIDE DECAY-HEAT REJECTION SYSTEM AND RETROFIT METHOD
A diverse, passive reactor-safety overlay that redirects shutdown decay heat through the steam generators to an external water heat sink—without relying on off-site AC power or conventional coolant pumps.
BOIL THE LAKE. NOT THE REACTOR CORE.
01 / System
Use the reactor's own heat-transfer pathway.
Following a reactor trip, the core continues producing decay heat. With the primary boundary intact and adequate coolant inventory, natural circulation can move that heat to the steam generators. The RMW overlay gives secondary steam a dedicated route to a remote external heat sink.
Uses reactor-generated secondary steam as the transport agent—without a conventional electric pump.
Condenses steam in an isolated submerged exchanger; a direct diffuser remains a sacrificial final backup.
02 / Screening calculation
Shutdown heat removal at engineer-readable scale.
Reference case: a 3,400 MWth AP1000-sized two-loop PWR. This is a preliminary heat-duty screen, not a reactor safety analysis or licensing calculation.
10-MINUTE DECAY LOAD3,400 × 2.33%= 79.2 MW
≤
RMW DUTY, ONE TRAIN OUT2 × 40 MW= 80 MW
REFERENCE RESULT
Three trains. Any two carry the cited load.
Three independent 40 MW trains provide 120 MW installed capacity. With one train unavailable, the remaining 80 MW equals or exceeds the cited reference heat load from ten minutes onward.
| Time after shutdown | Decay heat | Reference load |
|---|---|---|
| 10 minutes | 2.33% | 79.2 MW |
| 30 minutes | 1.82% | 61.9 MW |
| 1 hour | 1.51% | 51.3 MW |
| 2 hours | 1.15% | 39.1 MW |
| 4 hours | 0.965% | 32.8 MW |
| 8 hours | 0.778% | 26.5 MW |
ṁ = 40 MJ/s ÷ 2.1 MJ/kgApproximately 68.4 tonnes per hour of secondary steam and condensate.
A = Q ÷ (U × ΔTLM)Screened at U = 1–2 kW/m²·K and a 40 K log-mean temperature difference.
≈ 3,060 m³/dayActual closed-condenser rejection distributes energy through warming, mixing and evaporation.
03 / Engineering boundary
Defined for the intact-primary shutdown case.
Station blackout / loss of normal heat sink
- Reactor successfully tripped
- Primary pressure boundary intact
- Adequate primary coolant inventory
- Natural circulation available
- Conventional pumps and AC unavailable
Primary-system LOCA
The reference case does not replace emergency core cooling, primary inventory makeup, containment cooling or the AP1000's installed passive systems.
Coupled transient analysis
max Tclad(t) < 600°C
Confirmation requires a validated TRACE or RELAP5-class plant model.
Licensing · Engineering · Development
Advance the reduction to practice.
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