The Improvement of Overtemperature DeltaT and Overpower DeltaT Shutdown Algorithm
Li Gang · 2017
The Overtemperature OT DeltaT design is based on radial core peaking factors being no worse than design.It is not intended to protect for adverse radial power (quadrant tilt such as might be caused by misaligned control rods).The OT DeltaT RT protects the thermal design limit for departure from nucleate boiling (DNB), with resultant overheating of the fuel rod cladding, by preventing the combination of power, power distribution, pressure, and core inlet temperature that would violate the allowable design limit for the DNB ratio.The DNB ratio also depends upon the coolant flow into the core.DNB protection for flow transients is provided by the reactor coolant low flow RT and by the RCP underspeed RT.Coolant flow is considered constant for the OT DeltaT RT.The Overpower OP DeltaT design is based on radial core peaking factors being no worse than design.It is not intended to protect for adverse radial power.The Overpower OP DeltaT reactor trip protects the core against high linear power density.The article focus on the compare between analog and digital control technology for OT DeltaT、OP DeltaT algorithm.By using the digital control technology, the algorithm and signal process get best improvement.The protect function get more safety. OVERVIEWThe Overtemperature T ∆ RT protects the thermal design limit for departure from nucleate boiling (DNB), with resultant overheating of the fuel rod cladding, by preventing the combination of power, coolant temperature, power distribution, pressure, and core inlet temperature that would violate the allowable design limit for the DNB ratio.The Overpower OPDeltaT design is based on radial core peaking factors being no worse than design.It is not intended to protect for adverse radial power.The Overpower OPDT reactor trip protects the core against high linear power density [1] .Overtemperature and Overpower T ∆ protection used analog technology before in traditional pressurized water reactor nuclear power plant.The reactor trip setpoint is calculated by means of representation and fitting formula.With the development of sensor measurement technology, core thermal calculation and the application of computer technology in nuclear power plant, Digital instrument and control (I&C) has been able to support the calculation and modification of the complex core thermal power, and to create prerequisite for the use of more advanced Overtemperature and overpower T ∆ algorithm [2] .