Feedwater Temperature Control for Nuclear Reactor Power Adjustment
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Solution Overview
Problem
Natural circulation boiling water nuclear reactors (NCBWRs) lack a method to control power output uniformly, as they do not utilize recirculation pumps, leading to rapid and non-uniform power changes when control rods are manipulated, which can cause fuel cladding damage.
Innovation Solution
A system and method that involves heating the feedwater flowing into a reactor vessel using a heating subsystem and temperature controller to increase the temperature of recirculation water above a predetermined operating temperature, thereby reducing the power level generated by the reactor core without moving control rods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If control rods are manipulated to control power level in NCBWRs, then power level can be adjusted, but power changes occur at rapid and non-uniform rates causing fuel cladding damage
Solution Approach 1:
The patent changes the physical parameter of feedwater temperature to control reactor power level. By heating feedwater to elevated temperatures (e.g., 200-400°F above normal operating temperature) before injection into the reactor core, the recirculation water temperature is increased, which reduces the power level generated by the core. This provides uniform and controllable power adjustment without the mechanical shock and non-uniform power changes associated with control rod manipulation, thereby maintaining fuel cladding integrity while achieving power level control.
2Productivity
If recirculation flow is increased to obtain 100% power in typical BWRs, then power output increases uniformly, but NCBWRs lack recirculation pumps to implement this method
Solution Approach 1:
The patent replaces the mechanical recirculation pump system with a thermal control system. Instead of using pumps to increase recirculation flow for power control, the invention uses feedwater heating subsystems to elevate feedwater temperature before core injection. This thermal substitution achieves power level control without requiring complex recirculation pump infrastructure, making the method applicable to natural circulation reactors while maintaining uniform power adjustment capabilities.
3Reliability
If feedwater temperature is increased above predetermined operating temperature, then recirculation water temperature increases and power level reduces, but this requires additional heating subsystem infrastructure
Solution Approach 1:
The patent applies multi-functionality to the feedwater heating subsystem, which can serve both normal feedwater heating purposes and power level control functions. The same heating equipment used to prepare feedwater for reactor injection can be operated at elevated power levels to provide temperature-based power control. This eliminates the need for separate dedicated heating equipment solely for power control, reducing overall system complexity while maintaining stable and reliable power level adjustment capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for controlled and uniform adjustment of power levels in NCBWRs, reducing the risk of fuel cladding damage by managing the temperature of recirculation water, thus enabling safer and more stable power output management.
Implementation Method 1
a heating subsystem for heating feedwater flowing into a reactor vessel of a NCBWR to increase the temperature of recirculation water flowing through the core
Implementation Method 2
a temperature sensor operable to sense the temperature of the feedwater flowing into the reactor vessel
Implementation Method 3
By increasing the temperature of the feedwater flowing into the reactor vessel, the temperature of the recirculation water is increased above the predetermined recirculation water operating temperature flowing into the core causing a reduction in the power level generated by the NCBWR core
Data Source
AI summary
A system for controlling the power level of a natural circulation boiling water nuclear reactor (NCBWR) may include a heating subsystem for heating feedwater flowing into an annulus of the NCBWR to increase the temperature of recirculation water flowing through the core above a predetermined recirculation water operating temperature. Additionally the system may include a temperature sensor operable to sense the temperature of the feedwater flowing into the annulus. The temperature sensor is communicatively connected to a temperature controller operable to command the heating subsystem to increase the temperature of the feedwater flowing into the annulus to a requested temperature above a predetermined operating temperature of the feedwater flowing into the annulus. By increasing the temperature of the feedwater flowing into the annulus, the temperature of the recirculation water is increased above the predetermined recirculation water operating temperature causing a reduction in the power level generated by the NCBWR core.