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DEFENCE IN DEPTH
Defence in depth: sources

CATEGORY 5 SOURCES

 

Up to now, we have only mentioned Category 1 to 4 sources. However, there are a large number of Category 5 sources in general use, and in many cases there are no specific controls provided or required. The guidance given here can be used to rate events involving Category 5 sources.

Rate an event below the scale at Below scale/Level 0

Where there was no intent to provide specific controls

Rate an event at Level 1 where 

All intended safety provisions had clearly been lost,
or there is evidence of a significant safety culture issue

Generally, events are rated below the scale at Below scale/Level 0