Critical Heat Flux (CHF) testing is performed in full scale, horizontal CANDU fuel channels using directly heated fuel simulations with segmented (end plate) geometry and non-uniform axial and radial power distributions. The fuel simulations are equipped with moveable internal thermocouples which can be remotely positioned to monitor dryout over most of the surfaces of the downsrtream bundle elements. Fuel simulations representing 37- and 43-element CANDU fuel have been tested.
DNB Vertical Test Section
Boiling Transitiuon (BT) testing is performed in vertical BWR fuel channels (up to 10 x 10 full scale bundle arrays) using directly heated fuel simulations with non-uniform axial power distributions. The fuel simulators are equipped with internal thermocouples (up to 10) at precise locations to determine critical power.
A 16 MW DC power supply is available with 11 individually controlled power zones which provide up to 330 volts to neutral. The power supplies can be operated together for directly heated fuel simulations or individually with independent control of the output for each zone to allow on-line variation of the radial power distribution applied to an indirectly heated simulated fuel array. The power supplies are provided with accurate power metering and are controlled by the data acquisition computer to provide preset distributions and programmed power ramps.
A modern data acquisition system with up to 600 data channels monitors the test conditions as well as the dryout detection thermocouples at scanning rates of typically 10 Hz per channel.
Typical Facilities
Horizontal CANDU test facility using directly heated, segmented (end plates) fuel simulations with non-uniform axial and radial power distributions, and moveable internal thermocouples. The full scale CANDU fuel channel can simulate uncrept channels or crept channels at typical reactor conditions.
Vertical BWR test facility using indirectly heated fuel simulations with non-uniform axial and variable radial power distributions. Flow channels can accommodate up to 10 x 10 fuel arrays at typical reactor operating conditions up to 11 MPa.
DC power supply with up to 16 MW of 12 pulse rectified DC power in 11 individually controlled power zones which operate up to 330 volts to neutral. The power supplies can be connected with approximately half of the current flowing in the reverse direction to minimize magnetic forces in indirectly heated fuel arrays.
