English: secondary containment system
Welsh: system atal eilaidd
Subject: Amgylchedd
Welsh definition: Secondary containment is a second barrier or an outer wall of a double enclosure which will contain any leak or spill from a storage container.
Plural: systemau atal eilaidd
Notes: Yng nghyd-destun storio olew, nwy neu ddeunyddiau eraill a all fod yn beryglus i’r amgylchedd.