Heat exchanger limiting the risk of contamination between two fluids and aircraft comprising at least one such heat exchanger

A plate heat exchanger transferring heat between first and second fluids, comprising:

• a sealed housing, and
• a body positioned inside the housing, said body including a stack of at least a first assembly of first and second plates pressed against each other, between which the first fluid flows, and at least a second assembly of third and fourth plates pressed against each other, between which the second fluid flows, the first and second assemblies being arranged so that they transfer heat between the first and second fluids,
• wherein the first fluid is hydrogen and the housing comprises at least one sensor configured to detect a presence of hydrogen in the housing,
• wherein the housing defines a cavity in which the body is positioned, the housing comprises an atmosphere, and the atmosphere is an inert atmosphere or a vacuum,
• wherein the second fluid is a heat transfer fluid, and
• wherein the housing has a first pair of orifices through which the first fluid flows to and from the first assembly, a second pair of orifices through which the second fluid flows to and from the second assembly, and a tapping point through which at least one of oxygen is extracted from the cavity or an inert gas is introduced into the cavity.