Hydrogen Energy: Storage

A: Governing principle: Hydrogen compatibility is governed by material strength and microstructure, not just pressure test margin. Applied here: High-strength carbon steels under cyclic hydrogen service face embrittlement and fatigue per industry guidance, independent of hydrotest results. Distractor D catches those who focus only on MAWP math and ignore damage mechanisms.

A: Governing principle: Even with high-performance insulation, LH₂ tanks experience non-zero heat ingress driving boil-off. Applied here: 0.2–1% of 5,000 kg gives tens of kilograms per day, not hundreds. Distractor B appeals to LNG intuition but ignores hydrogen’s lower density and different thermophysics.

A: Governing principle: Polymer liners allow molecular diffusion of hydrogen even without discrete leaks. Applied here: Passing pressure tests yet elevated ambient readings align with permeation plus inadequate ventilation. Distractor B explains pressure loss but not a clean decay test.

A: Governing principle: PRDs manage pressure, not structural damage from external thermal attack. Applied here: Composite wrap can lose strength under fire even while pressure is relieved. Distractor B misreads PRD intent as blanket fire protection.

A: Governing principle: Hydrogen storage vessels fail by fatigue and damage accumulation under cycles. Applied here: ISO qualification requires demonstrating cycle life because static burst doesn’t capture hydrogen-assisted fatigue. Distractor D tempts those equating strength with durability.

A: Governing principle: Cushion gas maintains cavern pressure and cannot be cycled without risking integrity. Applied here: The pressure swing implies a large fraction locked in place, often near half the inventory. Distractor B ignores operational pressure constraints.

A: Governing principle: Trace water drives corrosion and embrittlement even in nominally dry hydrogen systems. Applied here: ppm-level moisture left from purging is enough to trigger damage. Distractor D explains corrosion but not the timing with gas changeover.

A: Governing principle: Loss of insulation causes violent boiling and mixed-phase discharge. Applied here: PRDs must handle flashing flow, not normal vapor rates. Distractor B reflects steady operation thinking applied to an upset case.

A: Governing principle: Detection mitigates delayed hazards, not instantaneous ones. Applied here: Jet fires can ignite immediately, bypassing detector response entirely. Distractor B fits detector logic but misses ignition physics.