Involved in pyrimidine base degradation. Catalyzes the reduction of uracil and thymine (By similarity). 5,6-dihydrouracil + NADP(+) = H(+) + NADPH + uracil Binds 4 [4Fe-4S] clusters. Contains approximately 16 iron atoms per subunit. Amino-acid biosynthesis; beta-alanine biosynthesis. Homodimer. Belongs to the dihydropyrimidine dehydrogenase family.