Thermal Stratification in the FFTF Heat Transport Piping Following Reactor Scram

摘要

No evidence of thermal stratification was observed in FFTF piping following scram to pony motor. Test results for the primary loop hot leg piping following scram to natural circulation flow show anomalously long transport times, piping top to bottom temperature differences and the thermal buoyancy parameter test indicated that thermal stratification should be significant. Thermal stratification does occur in the FFTF primary hot leg piping and could be expected to occur in other situations where the Richardson's Number exceeds the stratification threshold. It can affect transient thermal head development by distorting piping flow and temperature distributions from that obtained by one-dimensional calculations. For the FFTF, however, the impact is not significant in terms of piping stresses or peak core temperature following scram. (ERA citation 08:005086)