Yes, the RAD-Series RADIUS server is a 32-bit service which runs on both 32-bit and 64-bit Operating Systems. This is true for both the Solaris OS running on SPARC architecture and the Linux OS running on Intel x86 architecture. The only requirement is that the 32-bit C runtime libraries are installed.
A 64-bit version is being considered but is not currently on the roadmap.
If you would like Interlink Networks to develop a purely 64-bit version, please submit a feature request.