The safety in a cold neutron source (CNS) includes nuclear safety
radiation safety and hydrogen safety
with the latter being the most comprehensive. In general
the safety design of defence in depth implies defence levels and multiple physical barriers on the hydrogen system of CNS
in order to minimize the possibility of formation of a hydrogen-oxygen mixture. The implementation of the safety concept of defence in depth in a CNS under construction is presented
and it implies the design can ensure the hydrogen safety in the CNS.