PWR Control System Using Predicted Water Level Setpoints
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Solution Overview
Problem
Pressurized water reactors (PWRs) face challenges in controlling reactor power and preventing over- or under-pressurization due to large moderator temperature and void coefficients without soluble neutron poisons, leading to complex and frequent water level adjustments, which complicate control and generate additional radioactive waste.
Innovation Solution
A control paradigm that adjusts the pressurizer water level setpoint based on predicted changes in reactor power, using feedwater flow rate and temperature to manage reactivity and coolant volume, eliminating the need for soluble boron and simplifying reactor control by tracking the pressurizer water level limits with power changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If soluble boron poison is used to control reactivity, then reactor power control is simplified, but chemical complexity and waste generation increase
Solution Approach 1:
The patent removes soluble boron poison from the primary coolant system, extracting the harmful chemical substance while maintaining reactor control capabilities through purely physical parameters (temperature, pressure, water level). This eliminates chemical complexity and waste generation associated with boron management.
Solution Approach 2:
The invention changes the control parameters from chemical (boron concentration) to physical (coolant temperature, pressure, water level). By using feedback control based on temperature and pressure measurements, the system achieves reactivity control without chemical additives, transforming the control approach from chemical to physical parameters.
2Stability of the object's composition
If frequent water level adjustments are made to maintain pressurizer level, then pressure stability is improved, but operational complexity and waste generation increase
Solution Approach 1:
The patent implements preliminary action by anticipating water level changes before they occur. The feedback control system continuously monitors temperature and pressure, predicting future water level deviations and adjusting feedwater flow proactively to prevent excursions beyond acceptable ranges, rather than reacting after problems occur.
Solution Approach 2:
The invention employs feedback control where measured temperature and pressure data are continuously fed back to adjust feedwater flow. This closed-loop system automatically compensates for coolant volume changes, maintaining pressurizer level within acceptable ranges without frequent manual interventions or complex operational procedures.
3Stability of the object's composition
If feedwater flow is increased to compensate for coolant volume changes, then pressure stability is improved, but radioactive waste generation increases
Solution Approach 1:
The patent implements discarding and recovering by minimizing the discharge of radioactive coolant during level adjustments. Instead of frequently letting down and making up coolant, the system recovers and reuses coolant within the closed loop, only making minor adjustments to maintain pressure stability, thereby reducing radioactive waste generation.
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 simplifies reactor control during power transients by naturally accommodating coolant volume changes, reducing the frequency of water makeup or letdown events and minimizing radioactive waste generation, while maintaining stable reactor operation without the use of soluble neutron poisons.
Implementation Method 1
a reactor core disposed in the pressure vessel
Implementation Method 2
Hot, subcooled water is circulated between the reactor core and one or more steam generators to transfer energy from the reactor core to the steam generator
Implementation Method 3
An electrically heated pressurizer is used to control the reactor coolant system pressure
Implementation Method 4
The PWR contains a steam region that controls the pressure and changes its volume to accommodate changes in liquid volume
Implementation Method 5
Hot, subcooled water is circulated between the reactor core and one or more steam generators to transfer energy from the reactor core to the steam generator
Implementation Method 6
the one or more steam generators are located inside the pressure vessel
Data Source
AI summary
A pressurized water reactor (PWR) comprises a pressure vessel, a reactor core disposed in the pressure vessel, an integral or external pressurizer, primary coolant disposed in the pressure vessel and heated by operation of the reactor core, and a steam generator disposed in the pressure vessel and configured to convert secondary coolant in the form of feedwater into steam by heat transfer from the primary coolant heated by operation of the reactor core to secondary coolant in the steam generator. A controller is configured to perform a PWR control method including the operations of (i) adjusting one or more parameters of the PWR and (ii) adjusting a pressurizer water level setpoint based on a predicted direction and magnitude of change of a pressurizer water level of the PWR predicted to result from the adjusting (i).