> once the sodium hydroxide solution has cooled, add 5 gallons of
> concentrated "acide chlohydrique" to 45 gallons of caustic.

That is hydrochloric acid, HCl, muriatic acid, whatever...

Casually adding a concentrated acid to a strong alkali is often a dangerous
activity for an unprepared, untrained and unprotected person.  Whether a
unexpected and violent reaction may occur in this case depends on a number
of factors, including the size and shape of vessels, the concentrations of
the acid and base, the temperatures of the solutions, etc.

In any case, this whole neutralization procedure is likely entirely
unnecessary, since NaOH is a common drain cleaner and solutions of NaOH can
just be poured, carefully, in reasonably small amounts like we are likely to
use, down any drain that leads to proper sewage treatment (not a pond or
river).

Moreover, it is entirely unnecessary to use NaOh on a hive tool.  Ordinary
household bleach used full strength (5.25% sodium hypochlorite) will do the
job with much less risk.

Adding NaOH to water in a small container is highly exothermic and not a
reasonable thing to do for a little disinfecting job.

allen