[BitWielder1]

Sodium reacts violently with water.
More water will just make it worse.
Wonder how a smashed open sodium battery will react to a fire hose.

[TChad]

Sodium reacts violently with water.

Ah, the joys of high-school chemistry class.

Elemental sodium flushed down the toilet.

[Svartalfiar]

Sodium reacts violently with water.
More water will just make it worse.
Wonder how a smashed open sodium battery will react to a fire hose.

And yet all table salt (sodium chloride) does with water is dissolve in it.

Are these batteries using pure sodium (highly doubtful)? Flammability and reactivity can vary greatly depending on what other stuff the batteries are made out of. They may be completely inert, or just as explosive as you think. I didn't see much clarification on that.