Thermally activated trigger device

摘要

A thermally activated trigger device 10 comprises a pressurized closed vessel 11 with a piston 12 slideably mounted in it to divide it into two compartments 14 and 16. A fluid such as an inert gas is contained within the compartments at substantially the same pressure. One end of one of the compartments has venting means 24, such as a normally closed pipe which vents the fluid from the compartment once the pipe becomes open by rupture or melting at an elevated temperature. The resulting pressure difference between the compartments on venting of the fluid moves the piston which is connected to an actuator means for performing a desired control or safety shut-down function. The trigger device is useful for performing many control and safety shut-down functions, particularly for rendering a nuclear space reactor subcritical upon reentry to the earth's atmosphere.