Attempt to Estimate Reactor Period by Natural Mode Eigenvalue Calculation

Central Research Institute of Electric Power Industry, 2-11-1, Iwado Kita, Komae City, Tokyo 201-8511, JAPAN

^* Corresponding Author, E-mail: nauchi@criepi.denken.or.jp

Abstract

A calculation technique of the inverse reactor period of a perturbed state is investigated. That is achieved by solving the natural mode equation which expresses the neutron balance where the core power changes exponentially with time. The technique is implemented into the MCNP-5 code and tested for perturbed states. The convergence of the calculated inverse reactor period is observed and the ratio of the converged values to experimental data in literature ranges 0.93~1.28. The error would be mainly attributed to estimations of the neutron balance between production and annihilation.