This invention relates to a device and a process for leak detection and location in a nuclear plant, with a manifold (2) permeable to the material to be detected connected to a pump (3) and a sensor (5) for the material. The sensor (5) is to contain a detector for the radioactivity of the material, or upstream of the sensor (5) there is a branch pipe (12) connected to a radiation detector (7). If radioactive substances reach and enter the manifold (2), a conclusion on the leakage point can be reached from the time taken by the radioactive substances to reach the detector (7).
