TWINKLE: a multidimensional neutron kinetics computer code

The TWINKLE code is a neutron kinetics code which solves the multidimensional, two group transient diffusion equations using a finite-difference technique. The code contains a detailed six-region fuel-clad-coolant transient heat transfer model at each spatial point for calculating doppler and moderator feedback effects. The method of applying feedback corrections to the basic raw cross-sections is patterned after the design nuclear codes presently in use at Westinghouse. The code performs its own steady state initiation. Up to 2000 mesh points can be used, in one, two or three dimensional rectangular geometry. The code has been used for rod ejection, anticipated transients without trip, loop stop valve opening, and other transients. 11 references. (U.S.)