Subcriticality Monitoring for Lead-based Zero Power Reactor Venus-Ⅱ Using Pulsed Neutron Source Method

In this paper, the pulsed neutron source method was used to determine the subcriticality of four different configurations of lead-based zero power reactor Venus-Ⅱ. Basic theory, measurement system and experimental results of pulsed neutron source method were briefly introduced. The subcriticality for the studied reactor configurations was extracted through the evolution of the counting rate of detectors using the area-ratio method. The measured results of different positions exhibit obvious discrepancies, especially for the effective neutron multiplication factor k_eff≈0.94. Two kinds of correction methods, including the correction factor and the generalized perturbation method, were used to correct the measured results by MCNP simulation, and the corrected measurement results for different positions were found to be consistent. The corrected area-ratio method can be used to determine the subcriticality with satisfied accuracy while the k_eff of the system is around 0.94. This study can provide an useful technique to determine the subcriticality of ADS transmutation system.