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DEFENCE IN DEPTH
Defence in depth: sources

SOME EXAMPLES

 

These examples are self explanatory. The only point to make is to pay attention to the units!

Example 1

1 TBq 137Cs source; D value 0.1 TBq

CHECK YOUR ANSWER »

A/D = 1/0.1 = 10
Category 2

Example 2

1.9 GBq 60Co source; D value 0.03 TBq

CHECK YOUR ANSWER »

A/D = 0.0019/0.03 = 0.063
Category 4

Source category

Maximum rating under
defence-in-depth

1

2

3

4

 

You will note that Category 2 and Category 3 sources have the same upper limit in the defence in depth rating. They are, therefore, combined in the guidance on rating that follows.