Subterrene — Real Patented Technology + Thermodynamic Ceiling
LANL Nuclear Rock-Melting Penetrator, 1970s
Patent: US Patent 3693731A + supporting LANL technical reports. Real technology. Not theory. Not mythology.
Mechanism: compact nuclear reactor + lithium heat pipes leads to tungsten element at 1200°C leads to melts igneous rock leads to forces molten material into adjacent fissures leads to hardened vitreous glass tunnel lining. No spoil haulage. No concrete delivery.