Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.
The pressure tubes (PT) in the Indian Pressurized Heavy Water
Reactor (PHWR) are kept concentrically inside horizontal
calandria tube (CT), which is submerged in a moderator pool.
During postulated loss-of-coolant accident (LOCA) without
emergency core cooling system, the temperature of PT could
rise significantly. At elevated temperature, the weight of the
PT with the weight of fuel pins could cause it to sag. Before
sagging heat transfer from the PT to CT is mainly by
convection. Once the PT sags and touches the CT, heat transfer
mode changes to conduction. Direct contact between the PT
and CT increases heat transfer and checks the temperature rise
of the PT and limit the fuel heatup and subsequent degradation
of the reactor core. An experimental set-up is designed and
fabricated at Indian Institute of Technology Roorkee (IITR) to
simulate the LOCA in the Indian PHWR. From the
experimental investigation, it is found that the contact between
the PT and CT occurred at around 300 seconds after the
initiation of the simulation with corresponding temperature of
the PT at around 680°C. The experiment was continued after
the contact between the PT and CT and it is found that the
temperature rise of the PT was within 800°C. This work
demonstrates the inherent safety feature of Pressurised Heavy
Water Reactor.
