Assembly and method for injecting water containing a neutron-absorbing element to cool a nuclear reactor core in a crisis situation

An assembly is disclosed including a mobile structure (11) including a main pipe (30) equipped with a first end (12a) intended to be connected to a water supply and a second end (12b) intended to be connected to a circuit connected to the primary circuit of the reactor, and including between these two ends in the direction of circulation of the water, a pump (14), a water heating device (15), an injector (20) for continuously injecting the powdered neutron-absorbing element into the water of the main pipe, a first mixing and dissolving system (25) for mixing and dissolving powder with water and a controller driving and controlling the flow rate of the water and the flow rate of the powder injected.