NEXUS-a new nuclear data system for PWR and BWR core simulators

This paper presents an overview of NEXUS, a new nuclear data system which is being developed for light water core analysis by Westinghouse Electric Co. with its partners Mitsubishi Heavy Industries (MHI), and the Korean Nuclear Fuel Co. (KNFC). This nuclear data system is being implemented with two Westinghouse core simulators: ANC (Liu, 1985) for PWR cores and POLCA7 (Lindahl, 1995) for BWR cores. The paper presents a description of the methods developed and implemented in NEXUS, the computer codes which make up the system, the NEXUS system data, and the effort currently underway to qualify NEXUS for use in light water reactor design and safety analyses. In addition, some results from this qualification are presented which demonstrate the accuracy of NEXUS for representing cross section data. (authors)