Radiation belt transit times
LibreOffice spreadsheet here
Excel version here. Not sure about this, this is the translation made by LibreOffice and I don't have any computers that run Windoze or Excel.
LibreOffice is available for free download here
I used the equations here on the server sky website.
Conclusion: an transfer orbit from ISS altitude to GEO takes 21.8 minutes to pass through the inner van Allen belt, and 18.3 minutes to pass through on the way to the Moon.