Isolating primary circuit loop of gas-cooled high-temp. reactor - in cold shut=down state by inflatable bellows and balloons

摘要

A gas-cooled, high-temp. reactor comprises a number of loops in the primary circuit, each contg a heat exchanger and a blower. A cylindrical prestressed concrete pressure vessel houses the reactor in a central, lined vault and the circuit components in vertical pods around the vau the hot gas duct in each loop is coaxially positioned indise the return cool gas duct connecting each pod to the central vault. Each loop of the primary circuit can be individually isolated in two steps: In the first step an inflatable bellows is introduced into the annular space between the main vault liner and the side reflector, through a vertical shaft or passage leading up through the bottom of the pressure vessel into this annular space; a fixing and pulling device is used for introducing the bellows. In the second step, an inflatable balloon is introduced through a gas-supplied conveyor pipe and is used to plug the passage through the side reflector into the hot gas duct. This balloon and conveyor pipe are introduced into the pod and duct through a lateral access tunnel or shaft in the installation duct through the pressure vessel wall. The cut-off sealing system can be used with a cold, depressurised reactor for isolating a faulty loop to enable an inert gas atmosphere to be set up in that loop for maintenance and repair work.