Thank you @mkreher13 for your reply. Now, I can solve it. I have another question that I have tried to simulate triso at dimention of triso outer radius of micrometer but it shows kernel died. How can I simulate triso at dimention of micrometer?
I’m not entirely sure what the issue is, but I suggest that you start with the OpenMC TRISO example, and then change one thing at a time to slowly migrate it over to your specific dimensions. By making changes one at a time, you can identify what issues are causing the error.