According to Phillips' book, his main innovation was designing the shaped charges that brought the halves of uranium/plutonium together at the right rate. This

According to Phillips' book, his main innovation was designing the shaped charges that brought the halves of uranium/plutonium together at the right rate. This he achieved by calling around at Dupont (IIRC) until he found someone with the knowledge, which was willingly shared. (Presumably this critical info was made inaccessible after the paper was graded.) Freeman Dyson (who worked on the Manhattan Project and later at at IAS Princeton) reviewed Phillips' design, confiding to the course's professor, "Yes, this should work." Phillips' term paper was promptly classified. His only other feedback was to receive an A in the course.