I read there are low levels of radioactivity from the AI 200/4 micro and maybe a few others, but not enough to cause any discoloration of the glass.
The Nikkor-N 35/1.4 was the pinnacle of lens development when it was announced - a very fast wide-angle lens, with multicoating, close range correction, and special glass for controlling aberrations. Just a bit
too special in this case
When the K version came out they were able to substitute different glass with similar properties and no radioactivity.