Adm. H. G. Rickover's future as head of the Navy's nuclear fleet now rests squarely in the hands of Ronald Reagan, and Rickover's supporters seem to think that is good news. Officially, Navy Secretary John F. Lehman Jr. has to decide whether to give the 81-year-old admiral another two-year tour of duty. But the final decision has been bucked to the White House. The betting line yesterday among White House and congressional types was that the president will keep Rickover on the job.

The bureaucratic Kremlinogists were struck by Reagan's off-the-cuff comment at his press conference Tuesday, when the president laughed off the suggestion that he would fire Rickover or anyone else for being too old. Also noted with interest was an effusive pro-Rickover speech Wednesday by Vice Adm. S. A. White, commander of the Atlantic submarine fleet.

Nonetheless, much of the defense hierarchy, both civilian and military, dislikes Rickover and wants to establish some control over his considerable power. Some Pentagon officials think Rickover will get a conditional offer: he'll be kept on the job only if he agrees to accept another admiral chosen by Lehman to serve as his deputy.