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DEFENCE IN DEPTH
Defence in depth: facilities

THE UPPER LIMIT

 

We have been over the upper limit before; these principles of defence in depth apply to all facilities.

The INES approach is fairly simple and is illustrated here.

If an event of the maximum potential consequences, should all the provisions fail, could reach Level 5 or above, a near miss should be rated Level 3 on INES. Click here.

However, if an event of the maximum potential consequences, should all the provision fail, could only reach Level 3 or 4, a near miss should be rated Level 2 on INES. Click here.

Similarly, if an event of the maximum potential consequences, should all the provisions fail, could not even reach Level 3, a near miss should be rated Level 1 on INES. Click here.

POTENTIAL ACCIDENTS
NEAR MISS ACCIDENTS
This shows the rating for a near miss based on the rating for the worst possible accident should all provisions fail.