Complex sentence: The first shipments of enriched uranium to the Manhattan Project's Los Alamos Laboratory were made in March 1944, consisting of Alpha product enriched to 13 to 15 percent uranium-235.
Split into simpler sentences: The first shipments of enriched uranium to the Manhattan Project's Los Alamos Laboratory was made in March 1944. This consisted of Alpha product enriched to 13 to 15 percent uranium-235.