Natural Convection Shutdown Heat Removal Test Facility (NSTF) Repeatability and Project Status

摘要

The effect of weather has been determined to be non-negligible and furthermore, masks the influences from single parameter (e.g.cosine heated profile) test objectives. Thus a selected number of tests will include a forced flow condition via our loft blower fans. By defining a fixed mass flow rate through the system, we will be able to decouple the ambient weather from the system behavior and ensure that only the parameter of interest will influence the specific thermal hydraulic behavior of the system. Ultimately this will allow us to better characterize the system trends and behavior during parametric testing. However, not all test cases are appropriate for conducting under forced flow conditions. For example, the GA-MHTGR accident scenario implements a varying power-time history representative of a real life accident scenario, and thus dictating a forced mass flow rate would mask the natural system response. This test, along with others that require full natural circulation mode of operation, will be performed twice (summer, winter) to isolate the effects of weather and fully understand the single parameter of interest. Engineering controls have been used to reach steady-state operation in the scaled test facility, as unexpected flow reversals can occur from sharp weather induced perturbations (i.e. shifts in wind speed and direction). If left unmitigated, these have an impact on the heat removal performance. Thus, these influences must be addressed before one can ascertain the feasibility of the concept as a robust safety system in next generation reactors.