Nuclear propulsion manuals for the U.S. navy have similar wordings.

>By order of the commanding officer [actually a highranking person on carriers, compared to little ships where COs can be realtively junior and low ranking], this reactor limit may be ignored during tactical situations.

Legend has it that every CO (3, i think i heard) to invoke "when tactical" exceptions have been fired in the following review. The only thing worse than crashing a billion dollar boat is damaging the publics trust in naval nuclear power : )