Oak Ridge Associated Universities has a wealth of health physics history. Here's a link with some early papers by some famous folks and this link has photos from the health physics museum there:
Part 1 The Discovery Of Radioactivity
Part 2 The Medical & Geological Uses Of Radioactivity
Part 3 Fission & Fusion
Part 4 Nuclear Power (this part deals specifically with S. Africa's growing energy demands, and can be skipped if you're interest is history & basics. But there is a good description of pebble-bed reactors).
And here's a timeline of radiation research courtesy of the U.S. DoE Low Dose Radiation Research Program.