Involved in pyrimidine base degradation. Catalyzes the reduction of uracil and thymine (By similarity). Involved in the degradation of the chemotherapeutic drug 5-fluorouracil. 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. Worms lacking dpyd-1 exhibit increased sensitivity (decreased survival) to the chemotherapeutic drug 5-fluorouracil. Belongs to the dihydropyrimidine dehydrogenase family.