There are some after-the-fact memoirs, etc., that indicate that the issue was mentioned at meetings with Albert Speer, who was the highest-level official under whose auspices the uranium work took place, and Manfred von Ardenne, a physicist who pushed the program in 1940 or so.

We do not really have a sense of what Hitler knew or believed about nuclear fission as a possibility. It should be noted that the idea of atomic bombs "in the air" for years before nuclear fission was discovered (1939), but even after its discovery it was not clear that it would be possible to turn it into a weapon at all, much less in the short term. In Germany it was believed it would take years to complete such an effort and that it would be very costly. Speer decided in 1942 not to expand the program and instead to contract it to a small reactor research program. He later said that he did not ask Hitler about this; he says that by 1942 one could not really talk to Hitler about such things. In any case, it would have been a very small issue for Hitler to be dealing with, in the context of the war — the entire matter for Speer was that the scientists were telling him it couldn't be completed in time to be useful in the war, so it was not worth spending many resources on.

As to the "what they would do with them" question: they didn't have a real bomb program, and so that also meant they didn't have any plans, much less the knowledge they'd need (like the size and weight of the weapon) to make real plans. Practical plans for the use of the American bomb were not even made until the spring of 1945, very late in the development of the weapon.

For a very technical account of the German work, see Walker's German National Socialism and the Quest for Nuclear Energy. Some accounts of Speer, etc., are to be found in Paul Lawrence Rose's Heisenberg and the Nazi Atomic Bomb Project. It should be noted that there is a lot of nonsense about the German uranium program out there, both in print and on the Internet, so sorting through it can be difficult. In general all post-war accounts by Germans need to be read very carefully, given their tendency to tell self-serving stories about this always-contentious matter.

Hi there,

On /r/AskHistorians we often get questions along the lines of 'what did Hitler think about X' - I mean, as an April Fools joke one year, we changed the sub to /r/AskAboutHitler. However, for better or worse, many of these questions about what Hitler thought are, in the literal sense, unanswerable. We don't know what Hitler thought about many things, and especially about things which were inconsequential for him. Hitler did not keep a diary, and the collections of his private conversations is disjointed and nowhere near complete, being almost completely dependent on the post-war recollection of his intimates (who may also be unreliable in their recollections, especially given those circumstances).

Of course, you may still get an answer to this particular question! However, broadly speaking, proving the negative is very hard (there could be an 1965 article on the topic in Swahili), and if you've asked a question which is almost certainly "We don't know, and he probably didn't care anyways", few historians familiar with the topic matter actually are going to want to put in the necessary gruntwork, doubly so about a man who on a personal level was decidedly uninteresting.

For more information that will be helpful in understanding the context around your question, please read /u/commiespaceinvader's wonderful post on why Hitler's opinions actually aren't that interesting, and please see here for an example of a historian attempting to find evidence about Hitler's thoughts on a topic, but finding that it is likely unanswerable.