The interaction of molten-lithium droplets with water is studied exper
imentally. In one set of experiments, droplets of approximately 10- to
15-mm diameter are injected into a vessel filled with water. The reac
tion is filmed, and pressure measurements are made. The initial metal
and water temperatures range from 200 to 500-degrees-C and 20 to 70-de
grees-C, respectively. It is found that when reactant temperatures are
high, an explosive reaction often occurs. When the initial lithium te
mperature is >400-degrees-C and the water is >30-degrees-C, the explos
ive reactions become much more probable, with pressure peaks as high a
s 4 MPa. The reaction is modeled to explain the temperature threshold
for this metal-ignition phenomena. Results with the model support the
hypothesis that explosive reactions occur when the lithium droplet sur
face reaches its saturation temperature while the hydrogen film surrou
nding the drop is relatively thin. A second set of experiments measure
s the reaction rate of nonexplosive lithium- water reactions. The test
geometry parallels that of the previous experiments, and the reactant
temperature combinations are deliberately kept below the observed ign
ition threshold. Two separate methods are used to determine the reacti
on rate in each test: One uses a three-color pyrometer to measure the
drop temperature as the lithium rises through the water, while the oth
er consists of a photographic technique that measures the amount of hy
drogen generated. Measured reaction rates range from approximately 10
to 50 mol/s.m2 with good agreement between the two measurement techniq
ues. The data do not show any significant variation in the reaction ra
te as a function of either the initial water or initial lithium temper
ature.