Scrap Variances and Lot Size Independent Activities

I am working on explaining, in great detail, how scrap variances work to my superiors.

I am struggling on understanding how lot size independent activities are allocated into the scrap variance calculations.

For example, I have a material with a costing lot size of 110 and a lot size independent activity (machinery setup) of 0.3 hours.  On a particular production order, the planned delivered quantity is 257, the confirmed order delivery is 252 and the actual delivery is 279.  The order header scrap was changed to 12 pieces, forcing the order scrap percentage to 4.62%, resulting in a target scrap of 12.89 pieces.

When I pulled the information in KKS2, the amount attributed to the lot size independent activity was 0.015 hours.  I tried to reverse engineer the math behind the result, but nothing seems to make sense.  Does anyone out there know how this works so I can recreate the math?

Thanks,

Matt