I was thinking multiple long skinny tubes with etchings that make them more likely to split lengthwise. Maybe with a spring loaded/powered agitator so when the tube breaks there's some mechanical flinging/mixing of the inner chemical.

But I'm not a chemical processes engineer, so I don't know how much mixing is needed. But the existing emergency plan was to inject the the chemical through a single valve, so it seems like the dispersion and mixing requirements in this case seems to be low.