Abstract: The invention pertains to a method and to an arrangement applicable to a container or to a chamber, for instance to a security chamber or to a security container for valuable articles. The container/chamber (20) has a casing or shell (10) in which an explosive substance or a burstable item is housed. The arrangement includes at said shell (10) means (50; 50?) for detecting ambient temperature or shell temperature. The explosive substance is detonated or the burstable item is depressurised to prevent bursting of the outer casing/shell (10) of the container or said chamber at a predetermined temperature limit value. The means (50; 50?) for detecting the ambient temperature or the shell temperature is disposed essentially across the whole surface of the shell/casing (10).