Nuclear facilities - Ventilation penetrations for shielded enclosures

This International Standard specifies the requirements for the construction and the installation of radiobiological shielding devices used as ventilation passages through shielded enclosures with concrete or leaded walls to protect against gamma radiation. This International Standard applies to all shielded containment enclosures used for handling radioactive products or material emitting penetrating radiation (gamma or neutrons) in such quantities and of such emission rate that these products must be handled remotely behind a shielding wall. Typically, the enclosures considered cover all types of nuclear fuel cycle installations: reprocessing plants, hot activity laboratories, plutonium solution handling facilities, shielded cells, waste storage installations, etc. It could eventually be applied to particle accelerators, primary containment of research reactors, fusion research reactors, radiographic installations, neutron generators, etc. However, pressurized vessels, sealed sources, transport packaging for radioactive materials, as well as enclosures, primary circuits and vessels of nuclear power plants have been deliberately excluded from the scope of this International Standard. This International Standard specifies general and detailed principles which shall be respected when designing ventilation penetrations for shielded enclosures. These specifications can be divided more generally into two categories of guidance, which apply to the two following systems of ventilation penetrations for shielded enclosures already in use: the first corresponding to the most important conventional systems used worldwide, and the second corresponding to an alternative method, called the 'cast iron helix' technique