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DEFENCE IN DEPTH
Defence in depth: reactors

GENERAL APPROACH FOR LEAKS AND DEFECTS 'POTENTIAL' EFFECTS

 

Step 1:
Assume structure failed or action not taken

Step 2:
Identify what the INES rating would have been

Step 3:
Reduce rating based on likelihood of assumption in step 1

The first part of the process (steps 1 and 2) identifies the significance of the component in which the defect or leak occurred. It does this by assuming that the defect actually led to failure, or the leak reached its maximum size, and then calculating what the INES rating would be.

Obviously, this is not the actual rating so the third step is to reduce the rating depending on how likely the defect was to lead to failure or to lead to the leak getting worse.

Let’s work through an example.