UCC12040: UCC12040DVE recommendations to suppress this noise coupling

Tool/software:

Hi, 

Currently we are using UCC12040DVE isolated DC/DC converter in our MC design.  This went through EMI test.

The conducted emissions test was performed per the DO-160G section 21. The 8MHz noise peak was detected from the secondary side or isolated ground plane.

I have attached the schematic and layout of the design. 

Are there any recommendations to suppress this noise coupling?