Was Dunkerque's bunker fuel itself an explosive?

Was the heavy bunker fuel between Dunkerque's boilers and magazines itself explosive?

No. The concern was combustible fuel being heated by a boiler failure or shell explosion.

Heavy bunker fuel is acknowledged to be different from an explosive. The concern is that a boiler accident or bursting shell could heat the fuel around it. The objection to its position between magazines and machinery is therefore about combustible material exposed to an adjacent accident.