Developments of the sodium fast reactor analysis code SARAX: methods and verification

A new code system named SARAX for the fast reactor design and fuel cycle analysis was recently developed. The SARAX system mainly consists of two parts. The few group constants were generated by the SARAX-FXS code and the steady-state, fuel cycle and transient calculations were done by the SARAX-FR code. This paper presents the models adopted in the new codes and the verification test problem results are given to show the current capability and accuracy. The verifications are based on the OECD fast reactor benchmarks, which consist of four difference fast reactor designs. The few group cross sections, k_eff and power distribution were calculated with different models of generating few group constants. The results were compared with a continuous energy Monte-Carlo calculation. The relative differences of k_eff between SARAX and the reference code were less than 100 pcm for the large size cores and 300 pcm for the medium size cores. The RMS value of power distribution was less than 3%. Besides, the Doppler constants, void worth, control rod worth and reactivity swing were also calculated and compared. (authors)