Abstract: Protective sheath for optical or electrical conductors hardened with respect to X-rays.It comprises a flexible sheath formed from a resin matrix containing in regularly dispersed powder form at least one metal and/or at least one inorganic compound of a metal, said metal having a high atomic number of at least 47, a covering placed between the optical fibre and the X-ray protection sheath and optionally a mechanical protection sheath made from plastic directly covering the optical fibre.

Abstract: Protective box for electronic circuits hardened with respect to X-rays. The protective box comprises a base and a cover fixed to the base, formed from a rigid mechanical structure constituted by a composite material formed by a fibre-reinforced resin, an X-ray protection material partly covering the outer surface of the mechanical structure, said X-ray protection material being formed by a resin matrix containing a powder of a metal with an atomic number at least equal to 47 and with a melting point at least equal to 630.degree. C., a material formed from an element with a low atomic number forming the outer surface of the cover and optionally a good electricity conducting material covering the inner surface of the mechanical structure.