PWR-MOX/UOX-TRANS, OECD/NEA US-NRC PWR MOX/UO2 Core Transient Benchmark

Description of benchmark: The present benchmark is designed to provide the framework to assess the ability of modern reactor kinetic codes to predict the transient response of a core partially loaded with MOX fuel. This benchmark employs many of the characteristics of the NEACRP L-335 PWR benchmark proposed by Finnemann in 1991 which was designed to assess the ability of spatial kinetics codes to model rod ejection transients. The current problem adds the complexity of modelling a rod eject in a core fuelled partially with weapons grade MOX. The core chosen for the simulation is based on four-loop Westinghouse PWR power plant similar to the reactor chosen for Plutonium disposition in the U.S. The problem is designed primarily to assess core simulators, and therefore few group constants are specified at the level of homogenized pin cells. However, some participants may wish to utilize their own cross section generation methodology or to model explicitly the heterogeneous pins in their core simulators. Therefore, the benchmark also specifies material compositions and pin geometries in order to reach the widest range of participants and in order to be applicable to continuing code developments in which heterogeneous full core transport transients are becoming possible