Abstract: The present invention relates to a standard fission product emission device, for detecting failed fuel elements in a nuclear reactor of the type cooled by pressurized water, said reactor comprising a pressure-resistant vessel and a core constituted by fuel element assemblies, wherein said device comprises a hollow rod, adapted to be inserted into said vessel and defining a chamber divided into a first chamber and a second chamber located at the end of the rod by a constriction creating a first drop in pressure, said second chamber comprising on its wall a deposit or a metal plate of radioactive material and communicating with the vessel of the reactor, when said device is in position, by a nozzle creating a second drop in pressure greater than the one created by said constriction, a first tube disposed in said rod and opening out at the end of the first chamber remote from the second chamber, said first tube being adapted to be connected to a source of pressurized water at a pressure greater than that of the

Abstract: A sample of hot fluid under pressure circulating in a main circuit is admitted into a cavity formed within a sampling unit. The temperature and pressure of the fluid within the cavity are brought to the same conditions as in the main circuit and the cavity is then isolated after thermal stabilization of the main circuit. The sampling unit is isolated, then cooled in order to reduce the pressure within the cavity. A supporting shield which normally covers a thin window formed in the bottom cavity wall is withdrawn by sliding and the fluid is analyzed across the window.