First off, you might check out /r/genealogy. They are going to be very familiar with the sort of research you seem to be interested in, which is not exactly the same as what professional historians do, though it often overlaps.

A Google search reveals to me that Bristol Steel is still operating, so your first step should be to contact them. They likely have a corporate archive, and the archivist there might be able to help you. Archivists are wonderful resources - they know what their collections contain and can help you access them efficiently and effectively. That said, a corporate archive does not necessarily exist to help historians, family or otherwise. It exists first and foremost to be a repository of the records of a corporation, which is often required for legal reasons. Corporations, especially ones in heavy industry or that required tight security, might not be interested (or even legally able) to share such records. But it can't hurt to ask. ETA: The Bristol Steel I found on Google is located in Michigan, not Kentucky, so it might not be the same corporation. You'll have to figure that one out. If the company your father worked for is defunct, perhaps whatever concern bought them out might have the records. They might also be with a local university or historical society, but then again employment records contain a lot of sensitive information, such as SSNs, so they may be inaccessible or even destroyed.

Beyond that, you should perhaps think about contacting a local historical society or university archive/library. They may have more extensive knowledge about local history than this collection of strangers, most of whom are like me and have never even heard of Jenkins, KY, much less know the details of doing historical research there.

Good luck!

If he was a contractor at "Bristol Co." (the only entry I have in my file of contractor names), they were under contract to develop "standard items of equipment" for the Y-12 (electromagnetic enrichment) plant at Oak Ridge. Which is not very illuminating, is it? It means that they were one of the hundreds of contractors that were used for some of the off-the-shelf sorts of things they needed at Oak Ridge (as opposed to a place that developed specialized equipment).

The difficulty you're going to run up against, here, is that some 210,000 people were involved in the construction of Oak Ridge, while another 180,000 or so were involved in the "operations" of it. This only counts the directly-hired contractors, not the people who worked at the businesses where things were purchased from under subcontract (of which there were several hundred). So it's entirely possible that he worked on the construction of Oak Ridge in one capacity or another, but also entirely possible that this would have left behind very little archival record, because unless he was fairly high up on the rosters, he would not have been recorded in any of the permanent files. There were so many wartime investigations for security background checks that the FBI had to take over a stadium to store them (the DC Armory) during the war. Some of these files may still remain, but a lot of them have been destroyed and are quite hard to get ahold of (unless the subject subsequently got a "full" FBI file for some other reason).

I ran his name through my files and nothing came back, which means nothing other than he wasn't high enough in the ranks to show up in the kinds of sources I have (which are mostly high-level).

Random thought: you might see about requesting an "Itemized Statement of Earnings" from his Social Security files, which might give you some clue as to exactly who he worked for during the war. (I've never tried it before.) If you knew his occupational dates and the names of the companies it would be relatively easy to look up information on them in a source like the Manhattan District History (the way I did for "Bristol Co.").