Study of enhanced droplet cooling across grid spacer in LOCA reflood of PWR by LDA measurement
Thesis/Dissertation
·
OSTI ID:6979439
An experimental investigation of droplet-vapor mist flow across a test grid spacer was conducted. The study sought to simulate the grid spacer enhanced droplet cooling under reflooding conditions in the loss-of-coolant accident (LOCA) of a pressurized water reactor (PWR). The study also provides a fundamentally improved understanding of the basic mechanisms concerning droplet dynamics and droplet-vapor mist flow heat transfer. An understanding of water droplet dynamics is necessary for explaining the sharp drop in cladding temperature observed immediately downstream of the grid spacer. A test channel that simulates the PWR reactor rod bundle was built to conduct both temperature measurements of the rod cladding and vapor flow, and droplet dynamics measurements before and after the grid spacer. The large droplets ( >1mm), which thermally are relatively inactive, are intercepted by the grid spacer and broken down into smaller, thermally more active, droplets (<200 /sup +/m). This investigation discusses droplet dynamics and heat transfer mechanisms across the grid spacer. It also provides a detailed discussion of the grid spacer's quenching behavior, the cooling downstream, and the droplet enhancement cooling, combined with the results of the full-length rod-bundle test.
- Research Organization:
- State Univ. of New York, Stony Brook (USA)
- OSTI ID:
- 6979439
- Country of Publication:
- United States
- Language:
- English
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22 GENERAL STUDIES OF NUCLEAR REACTORS
220900* -- Nuclear Reactor Technology-- Reactor Safety
ACCIDENTS
DROPLETS
DYNAMICS
ENERGY TRANSFER
FLUIDS
GASES
HEAT TRANSFER
LOSS OF COOLANT
MECHANICS
PARTICLES
PWR TYPE REACTORS
REACTOR ACCIDENTS
REACTORS
SIZE
VAPORS
WATER COOLED REACTORS
WATER MODERATED REACTORS