Abstract
Flash evaporation of a superheated water droplet in heavy liquid metal coolant (lead) is considered, in application to the analysis of a lead-cooled fast reactor steam generator tube rupture accident. The model is based on thermodynamic equilibrium formulation for the expanding water-steam mixture and inviscid compressible formulation for the surrounding liquid lead, with the interface conditions determined from the solution of the Riemann problem. Numerical solution is performed in the spherically symmetric geometry using a conservative numerical scheme with a moving sharp interface. Transient pressure and velocity profiles in each phase are presented for the parameters typical of the steam generator tube rupture accidents, demonstrating the process of boiling water expansion and pressure wave formation in the coolant. The results obtained are compared with a simplified model which considers the volume-averaged parameters of boiling water droplets and considers coolant as an incompressible liquid. Good agreement between the full and simplified models is demonstrated. Impacts of coolant flow on structures caused by pressure wave propagation and subsequent coolant flow are discussed.
Highlights
Lead-cooled fast reactors (LFRs) are considered a prospective avenue of nuclear industry development towards future systems possessing higher efficiency and operational and safety features in comparison with today’s conventional light water reactors (LWRs) [1,2,3,4]
The purpose of the current work is to consider an elementary process of steam generator tube rupture (SGTR) accident, namely, rapid boil-up of a high-pressure water droplet immersed in low-pressure liquid lead
For a water droplet of 13 mm initial radius, the characteristic arrival time to a point located at 10 cm distance from the droplet is of the order of 0.05 ms, and pressure jump can be as high as 3.5 MPa
Summary
Lead-cooled fast reactors (LFRs) are considered a prospective avenue of nuclear industry development towards future systems possessing higher efficiency and operational and safety features in comparison with today’s conventional light water reactors (LWRs) [1,2,3,4]. Since no energetic reactions and hydrogen generation occur in molten lead coolant in the case of steam generator tube rupture (SGTR), reactor system design can be simplified significantly because the steam generator can be placed directly in the primary heat circuit, without the need of any additional heat transport systems. It should be noted that SIMMER III is a Eulerian multifluid code in Science and Technology of Nuclear Installations which interactions at the scales of a single water droplet are not simulated directly but are taken into account via relevant closures. Such predictions can potentially be improved by more detailed (time and space-resolved) analysis of the phenomena involved in SGTR accidents. The experimental results have shown that the chain ruptures of the neighboring tubes were unlikely, even if the tubes were initially defective
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
