[en] Previously existing decay and photon libraries for the ORIGEN computer code were updated by utilizing a variety of sources. Information obtained form the Evaluated Nuclear Structure Data File (ENSDF) at ORNL was used to revise the half-lives, branching ratios, and recoverable heat values for 427 isotopes. Fifty-seven delayed-neutron precursors were included, on the basis of information in ENDF/B-IV. The natural abundances and the Radionuclide Concentration Guide values were updated for all isotopes. The decay heat values predicted by use of the new decay library were found to compare favorably with those given in the proposed 1978 ANS Standard 5.1 (draft ANSI/ANS-5.1, ''Proposed American National Standard Decay Heat Power in Light Water Reactors''). A new photon library was also generated for 427 isotopes, based principally on data presented in ENSDF. The photon library includes decay gamma and x rays, conversion photons, (α,n) gamma rays, prompt and fission product gamma rays from spontaneous fission, and bremsstrahlung. Both of the revised libraries are listed. 1 figure, 9 tables