Nuclear Reactor Control Rod Positioning for Stable Criticality Prediction
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Solution Overview
Problem
Existing nuclear reactors, particularly 4th generation reactors like SMR, SFR, and VHTR, face challenges in accurately predicting and maintaining critical states due to the lack of soluble boron acid use, leading to convergence instability and inefficiencies in control rod positioning.
Innovation Solution
An apparatus and method using a neutron equilibrium equation and Monte Carlo nuclear design computer code to predict and stabilize critical states by adjusting control rod positions and angles, employing a processor and memory to calculate effective multiplication factors and neutron flux, and applying moving averages to reduce stochastic errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If control rod positions are adjusted to maintain critical state in soluble-boron-free reactors, then reactor operation stability is improved, but convergence instability occurs in Monte Carlo simulations
Solution Approach 1:
The patent implements a feedback mechanism where the Monte Carlo simulation continuously monitors the effective multiplication factor (k-eff) and adjusts control rod positions accordingly. The simulation compares the current k-eff with the target critical state and modifies rod positions to achieve convergence, thereby resolving the convergence instability issue while maintaining reactor operation stability.
Solution Approach 2:
The patent changes the parameter being optimized from fixed control rod positions to dynamic positions based on real-time reactor state variables. By adjusting control rod positions as a variable parameter rather than a fixed value, the system can adapt to changing reactor conditions and achieve stable convergence in Monte Carlo simulations while maintaining critical state.
2Measurement precision
If control rod positions are dynamically adjusted according to state variables, then critical state prediction accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary calculations and pre-determines control rod position adjustments based on reactor state variables before actual reactor operation. By preparing lookup tables or pre-computed trajectories for control rod positions corresponding to different state variable combinations, the system reduces real-time computational complexity while maintaining high prediction accuracy for critical state.
Solution Approach 2:
The patent creates a simplified computational model that copies the essential features of the full Monte Carlo simulation but runs faster. This reduced-order model uses the same physical principles but with simplified geometry or approximation methods, allowing rapid prediction of control rod positions for different reactor states without the full computational burden.
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
Stabilizes nuclear reactor operation by accurately predicting and maintaining critical states, reducing convergence instability, and optimizing core design and safety margins.
Implementation Method 1
obtains an effective multiplication factor representing a ratio between a neutron production rate and a neutron annihilation rate in the nuclear reactor
Implementation Method 2
obtains a neutron flux and an effective multiplication factor representing a ratio between a neutron production rate and a neutron annihilation rate in the nuclear reactor
Data Source
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AI summary
Disclosed are an apparatus for controlling a nuclear reactor and a method thereof. The apparatus includes a processor and a memory. The processor obtains a neutron flux and an effective multiplication factor representing a ratio between neutron production and neutron annihilation rates in the nuclear reactor, obtains plural parameters related to neutrons by using neutron flux, updates a total insertion length representing an entire length of insertion of each control rod into a core by using at least one of an overlap length representing a length of overlap of the control rods in the nuclear reactor, the plural parameters, or any combination thereof, and identifies positions of each control rod for changing a state of the nuclear reactor to a critical state by using at least one of the updated total insertion length, the effective multiplication factor, or any combination thereof.