Individual:
http://rdf.iit.demokritos.gr/2014/iaeaSafetyGlossary/id163
Annotations (2)
-
nreo:canonicalLabel "defence in depth" (en)
-
skos:definition "1. A hierarchical deployment of different levels of diverse equipment <br/>
and 'procedures' to prevent the escalation of <i>anticipated operational occurrences<br/></i>and to maintain the effectiveness of physical 'barriers' placed between a <br/>'radiation' 'source' or 'radioactive material' and 'workers', 'members of the public' or <br/>the environment, in 'operational states' and, for some 'barriers', in <i>accident <br/>conditions</i>.<br/>
The objectives of 'defence in depth' are:<br/>
(a) To compensate for potential human and 'component' 'failures';<br/>(b) To maintain the effectiveness of the 'barriers' by averting damage to the 'facility'<br/>
and to the 'barriers' themselves;<br/>
(c) To protect 'workers', 'members of the public' and the environment from harm in <br/>
'accident conditions' in the 'event' that these 'barriers' are not fully effective.<br/>
INSAG defines five levels of 'defence in depth':<br/>
(a) Level 1: Prevention of 'abnormal operation' and 'failures'.<br/>(b) Level 2: 'Control' of 'abnormal operation' and detection of <i>failures.<br/></i>(c) Level 3: 'Control' of 'accidents' within the <i>design basis.<br/></i>(d) Level 4: 'Control' of severe plant conditions, including prevention of 'accident'<br/>
progression and mitigation of the consequences of 'severe accidents.'<br/>
(e) Level 5: Mitigation of radiological consequences of significant releases of <br/>
'radioactive material'.<br/>
The levels of defence are sometimes grouped into three 'safety layers': <br/>hardware, software and management 'control'.<br/>In the context of 'waste disposal', the term 'multiple barriers' is used to describe <br/>a similar concept.<br/>See Ref. [14] for further information.<br/>
2. The application of more than one protective measure for a given 'safety'<br/>
objective, such that the objective is achieved even if one of the protective <br/>measures fails. (From Ref. [1].)<br/>" (en)
Types (1)
Usage (23)