A Combined Analytical, Experimental and Simulation Investigation on LBE Natural Circulation Flow and Heat Transmission

As one of the proposed six types of Gen-IV nuclear energy systems, lead-cooled fast reactor (LFR) has some advantages in safety, economy, sustainability, and proliferation prevention. With its low melting point, chemical inertia, high boiling point temperature, pretty good neutronics and γ shielding ability, lead bismuth eutectic (LEB) has been one of the common choices of lead-base coolant for fast reactors. A certain natural circulation capacity might be achieved in LBE flow systems due to its relatively high thermal expansion and thus induced buoyancy. Consequently, for the purpose of enhancing natural safety performance and operation economy, as well as for other specific needs, natural circulation is, in recent years, considered for the main heat transmission system or residual heat removal systems in some LBE fast reactor designs. Study of LBE natural circulation along with its heat transmission performance is thus of quite significance for LBE natural circulation fast reactor design and natural safety performance improvement. In this paper, steady-state flow and heat transmission characteristics and behaviors of LBE natural circulation, as well as those of other coolant media (sodium and water), are theoretically and comparatively studied. Meanwhile, based on both the steady and transient natural circulation experiments on the LBE natural circulation test facility, namely, LNC-SJTU facility, the applicability of the fast reactor system analysis code FRTAC for LBE natural circulation transient simulation is preliminarily validated. And with the prediction of this FRTAC code, furtherly, effects of operating conditions as well as the corresponding fluid thermophysical properties, structural and geometric parameters of the loop, frictional and local resistances on the LBE natural circulation performances are quantitatively investigated.