THREE DIMENSIONAL KINETICS CODE RANCER AND ANALYSIS OF NEACRP ROD EJECTION BENCHMARKS.

A three-dimensional (3D) nodal kinetics code RANCER* has been developed. This code is an extension of the steady state three-dimensional diffusion code ANC (1) . RANCER code adopted the theta-weighted for time integration method which treats the kinetics equation exactly. In order to verify the adequacy of this code, we have performed several benchmark problems, including the TWIGLE (2) , the LMW (3) and the SPERT-III (4) . In this paper, we calculated the rod ejection benchmark problem of NEACRP. This benchmark has been widely used as the standard benchmark for PWR transient code. However, Reactivity Initiated Accident (RIA) benchmark problems at hot zero power (HZP) have high sensitivity of the inserted reactivity. In order to reduce uncertainty and compare with other kinetics codes, we calculated the sensitivity in each benchmarks. And we also confirm the adequacy of the code in this paper. * RANCER: Revised ANC for Evaluations of tRansients