ANSI 3.1 "Selection and Qualification of Nuclear Power Plant Personnel" replaced ANSI N18.1 (of the same title), and according to the American Nuclear Society website, was re-issued in 1993 and then revised again in 1999. I too have failed at finding a copy without having to pay for it!
Nevertheless, I believe Mr. Eric Bartlett is correct. The expectation is that the two years of working experience be computed based upon the equivalent of having worked 40 hours per week, 50 weeks per year. Years past, folks got their two years of experience working 12 hours a day, 7-days per week, in a liitle over one year. Sadly, a number of those folks gained "their experience" by sitting hatch watch or playing cards in the break room.
The regulators have put an end to that, for the most part. Utilities are now more vigilant at reviewing resumes, and although your resume may state you're an ANSI 3.1 tech, you may not be hired on in that capacity.
We've touched on this topic before. Utilties, with the encouragement of the Nuclear Eenrgy Institute and other regulators, are moving towards a universal task qualification system, whereby your individual qualifications will be entered into the "Personnel Acccess Database" (PADS) by the utility as you qualify to the tasks, and will then be accessible by all utiltiies. The expectation will be that you meet specific qualifications in order to be classified as a senior health physics technician, regardless of time or what your resume says. The industry is moving towards verifiable proof of a trained and qualified HP workforce.