Hazard screening for external events

A prehminary screening of the external events to be considered in the design of a research reactor can be done on the basis of a detailed hazard categorization. For facilities in the lowest category (hazard category 3) some extreme scenarios (aircraft crash, blast loads, tornado) may be screened out either by virtue of the selection of the site or on the basis of a low probabihty of occurrence. 

The screening process can then consider the potential for off-site and onsite consequences induced by the external event. Table 8 presents possible consequences of external events to be analysed for screening. 

External event Off-site damage Safety function affected Severity of potential damage and warning 

Geological and geotechnical hazard Loss of off-site power and other utilities Loss of access roads Structural stability and integrity Reactor could be critical or in shutdown state High Sudden action without warning 

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