Analysis of control rod withdrawal end-of-life tests in the PHENIX reactor at IGCAR

The post-analysis of control rod withdrawal end-of-life experiments, performed in the PHENIX reactor during June 2009, were carried out at IGCAR as a part of IAEA Coordinated Research Project (CRP) on "Control rod withdrawal and sodium natural circulation tests performed during the PHENIX end-of-life experiments". The main objective of this CRP was to assess the prediction capability of distorted radial power distribution due to absorber rod movement (insertion and/or withdrawal) at nominal power. In addition, core reactivity, absorber rod worth, S-curve, maximum neutron flux, SA-wise power and sodium heating deviation with respect to the reference core for various critical core configurations were analyzed. 3-D diffusion theory calculations using FARCOB (IGCAR) and ERANOS-2.1 (European) code systems were made for this analysis. IGCAR prediction of radial power distribution due to absorber rod movement is very close to the measured values. No significant deviation is observed between the results of FARCOB and ERANOS-2.1 and also between the results of other CRP participants. This benchmark exercise has provided a wide international forum to verify the method, computer codes and cross section data employed at IGCAR for the physics design calculations of sodium cooled fast reactors, by keeping the experimental data as the reference. (author)