Introducing NJOY 89

A new version of the NJOY Nuclear Data Processing Code is described. This version is called NJOY 89, and it supports most of the features of the new ENDF-6 format including the Reich-Moore and Hybrid R-Function resonance representations, heating and damage calculations that make use of File 6 energy-angle distributions, the revised File 7 format for thermal data, and multigroup transfer matrices based on File 6. The multigroup matrices can be computed for incident neutrons or charged-particles, and for outgoing neutrons, photons, charged particles, and recoil nuclei. The MATXS output, module has been upgraded to handle charged particles in order to enable the TRANSX code to prepare multiparticle coupled sets. The plotting module can display ENDF-6 format File 6 data in both 2-d and 3-d perspective forms. In addition, some remaining problems are discussed