Dynamic boiling tests in a 19-pin simulated LMFBR fuel assembly

A series of quasi-steady state tests were made to study dynamic boiling and to determine a boiling region which would not lead to immediate dryout and pin failure in the Thermal-Hydraulic Out-of-Reactor Safety (THORS) Facility (previously the Fuel Failure Mockup), an engineering-scale sodium loop for testing simulated LMFBR fuel assemblies at normal and off-normal operating conditions. These tests were made on an assembly consisting of 19 electrically heated pins of the same configuration as FFTF fuel. Approximately 50 flow transients were so conducted to boiling or near boiling over a range of flows and powers. Dryout occurred at three test conditions