4.6. Operational safety is provided by means of active and passive systems. Active systems could include monitoring for releases of radioactive material and operational controls, whereas passive systems could include engineered features such as shielding. Where appropriate, operational experience and technologies adopted from operating nuclear facilities (e.g. techniques for fuel handling) should be used in the development of safety systems for operational safety. Safety mechanisms for the post-closure period are distinct from those employed in the operational period, and therefore, the remainder of Section 4 provides recommendations on the approach to safety after closure of the geological disposal facility.