Most of the nuclear power plants in the world have complex
pipeline systems and they are operated under high temperature
and high pressure conditions. Therefore, the plant is at an accident
condition or under the normal operation, the possibility of pipe
break still exists. Some of them may be caused by the frequent
exposure to pressure wave oscillations like water hammering
phenomena.
Especially, the ‘‘steam bubble collapse” mechanism can be identified
which is responsible for steam condensation induced water
hammer in horizontal pipes. Steam bubble collapse induced water
hammer events happen if the following six conditions meet
(Griffith, 1996) (1) the pipe must be almost horizontal (max. pipe
inclination must be less than 5), (2) the subcooling must
be greater than 20 C, (3) the L/D (length-to-diameter ratio of the
tube) must be greater than 24, (4) the velocity must be low enough
so that the pipe does not run full, i.e. the Froude number must be
less than one, (5) there should be a void nearby and (6) the pressure
must be height enough so that significant damage occurs, that
is the pressure should be above 10 atmospheres. For these reasons,