Calculation of natural circulation under heaving motion

Wide validation of self-developed program of natural circulation under oceanic conditions has been conducted compared with experimental data of inclination, zero-power condition and hot-state condition. Experiments were performed on a full-scale, whole parameterization natural circulation loop designed with reference to 5 MW experimental low temperature nuclear heating reactor (NHR) of Tsinghua University. Investigation of natural circulation and parameter effect under heaving motion was carried out using the program and comparison of heaving, inclination and rolling on natural circulation respectively to reveal the influence mechanism. Results indicate that: (1) significant influence of heaving motion on natural circulation was observed, and heaving motion with high level of strength and long cycle would lead to severe flow fluctuation; (2) slight effect was caused by short cycle heaving motion which was completely different from long cycle heaving motion; (3) comprehensive action of alternating force and flow density distribution would result in natural circulation under heaving motion; (4) most severe accidents maybe result from the long cycle heaving motion rather than inclination and rolling motion. Investigation of influence of heaving motion on natural circulation could have important reference significance in the optimization design of nuclear reactors.