Pressurized Water Reactor Temperature Control via Dynamic Dead Band
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current control methods for pressurized water nuclear reactors face challenges in efficiently managing power variations and minimizing effluent volumes during load monitoring and frequency adjustments, particularly due to limited action speed of borication or dilution operations and significant strain on control rods and treatment costs.
Innovation Solution
A method that regulates the temperature of the primary cooling liquid by defining a setpoint temperature interval with variable amplitude, allowing free temperature fluctuation within this range without triggering control rod movements or boron concentration changes, thereby reducing control actions and effluent volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If control rods are frequently moved to maintain precise temperature control, then temperature stability is improved, but control rod wear and mechanical stress increase
Solution Approach 1:
The patent implements dynamic adjustment of the dead band width based on operating conditions. When the reactor operates near nominal power, a narrow dead band maintains tight temperature control. When operating at reduced power or during transients, the dead band widens automatically, reducing control rod movements and mechanical stress while maintaining adequate temperature stability.
Solution Approach 2:
The control system changes the temperature setpoint and dead band parameters dynamically based on power level and operational phase. This allows the system to maintain temperature stability when needed while reducing control actions during periods when frequent adjustments would cause excessive wear.
2Power
If boron concentration is adjusted frequently to control power, then power regulation precision is improved, but effluent volume and treatment cost increase
Solution Approach 1:
The control system uses partial boron adjustments combined with control rod movements rather than relying solely on frequent boron injections. This reduces the total volume of boron added and removed from the system, thereby reducing effluent generation while maintaining adequate power regulation precision.
Solution Approach 2:
The control rods serve as an intermediary mechanism between the temperature control system and the boron concentration system. By using control rods for rapid, precise adjustments, the system reduces the need for frequent boron concentration changes, thereby reducing effluent volume while maintaining power regulation precision.
3Speed
If control system responds rapidly to temperature deviations, then temperature control responsiveness is improved, but control mechanism wear increases
Solution Approach 1:
The dead band width is dynamically adjusted based on operating conditions. During steady-state operation, a narrow dead band provides responsive control. During transients or at reduced power levels, the dead band widens to reduce the frequency of control actions, thereby reducing mechanical stress while maintaining adequate responsiveness when needed.
4Measurement precision
If narrow temperature dead band is used for precise control, then temperature control precision is improved, but control action frequency increases
Solution Approach 1:
The control system dynamically adjusts the dead band width based on power level and operational phase. At nominal power with stable conditions, a narrow dead band provides precise temperature control. At reduced power or during transients, the dead band widens to reduce control action frequency, preventing excessive wear while maintaining adequate temperature control precision.
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 optimizes control rod movements and reduces effluent volumes by leveraging temperature reactivity within a defined setpoint temperature interval, minimizing the need for frequent control actions and extending the lifespan of control mechanisms.
Implementation Method 1
the control clusters made up of neutron absorbing element at different insertion positions so as to absorb more or less the neutrons
Implementation Method 2
regulating at least the average temperature of the primary coolant T avg
Implementation Method 3
adjusting the concentration a neutron absorbing compound, such as boron, in the primary coolant
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5c
AI summary
The subject of the present invention is a method for controlling a pressurised water nuclear reactor, said reactor comprising: a core producing thermal power and means for acquiring quantities representative of the operating conditions of the core (thermal power, temperature of the primary coolant); said method comprises a step of adjusting the temperature of the primary coolant if the temperature of the primary coolant, for a given thermal power, is not located in a temperature setpoint interval (ΔTREF) defined beforehand depending on the power of the reactor, said temperature setpoint interval (ΔTREF) being characterised by: an amplitude (ΔT) that varies over a thermal power range lying between N% and 100% of the nominal power, N lying between 0 and 100; a zero amplitude at 100% of the nominal power; and a zero amplitude at N% of the nominal power, said adjustment not being carried out provided the temperature of the primary liquid is inside said temperature interval (ΔTREF) for a given thermal power.