There's quite an array of colors available and some have a definitive application.
For the Nukes, low chlorides is the requirement. Not sure of the available colors in nuclear grade, but the inner paper core will have the word, "NUCLEAR" repeatly printed on it. I've hear Yellow, White and Green is on that list, but that's not verifed. In any case check the inner paper core and the manufacturer.
Why the color variations? TO BLEND!
The RPM at Watts Bar may have seemed somewhat rediculous on the issue, but if you want to identify a problem in a nuclear facility, slap something RED on it! Besides a standard color code for fire protection systems, equipment position indicators and Warning tags, RED should be used very sparingly! Since duct tape seems to be used so widely for temporary repairs, RED tape would be an invitation for a regulators attention! To much RED could possibly make the work force calis to the color and that could possibly set the course for a regulatory issue.
Watts Bar had tons of "red tape" hidden away, cause the RPM hated it. That RPM left for the "Ferry", and now Watts Bar has "Red Duct Tape" everywhere. It's even on the Xerox machine holding it together!
RED duct tape holding a BROKEN Xerox machine together and it's still in use?

Now that's Funny........RG!