Discrepancy in MCDANCOFF results betweent SCALE6.2.3 and SCALE6.3.1

[Nuria GH]

Dear SCALE Team,

I am encountering significant discrepancies in the Dancoff factors when running MCDANCOFF with SCALE6.2.3 and SCALE6.3.1 for BWR fuel assemblies. To check it, I used a simple test case: a BWR pin-cell with reflective boundary conditions (see attached input file).

The results are as follows:

• SCALE6.2.3: Dancoff factor = 0.48
• SCALE6.3.1: Dancoff factor = 0.075

I used the same input file with both versions and verified these results on both Linux and Windows systems. Is there any reasons for this discrepancy?

Thank you for your assistance.

Best regards,

Nuria