Surrogate Model Optimization for Nuclear Reactor Core Design

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Solution Overview

Problem

Current methods for designing nuclear reactor cores are inefficient, requiring months to determine if a proposed design satisfies all requirements due to slow computational processes and inability to handle complex interactions of physics disciplines, especially neutronics, thermal, and stress analyses.

Innovation Solution

The use of a machine learning-based algorithm that applies stochastic sampling and adaptive optimization techniques to rapidly identify optimal design parameters within user-specified constraints, integrating neutronics, thermal-hydraulic, and stress analyses, while reducing the need for costly computing resources and expert engineering time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional computational methods (MCNP, thermal simulations, stress analyses) are used to validate reactor core designs, then measurement precision and reliability are improved, but productivity is severely degraded due to months-long computation times

Engineering Contradiction:
Improvedesign validation accuracyVSAvoiddesign iteration speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent creates a simplified surrogate model (copy) of the complex reactor core physics system. This surrogate model replicates the essential neutronics, thermal, and stress behaviors but computes thousands of times faster than traditional methods. The surrogate model is trained on a dataset generated from high-fidelity simulations, allowing it to predict design outcomes with sufficient accuracy for iterative optimization while reducing computation time from months to hours.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent employs inexpensive, computationally lightweight surrogate models that can be rapidly evaluated thousands of times during optimization. These surrogate models are 'disposable' in the sense that they are simple approximations rather than high-fidelity physics solvers, allowing aggressive exploration of design space without the computational burden of traditional methods. The cheap evaluation cost enables parallel processing and extensive design iteration.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Reliability

If high-fidelity physics-based simulations are used to ensure design reliability, then measurement precision is improved, but loss of time increases dramatically

Engineering Contradiction:
Improvedesign requirement satisfactionVSAvoidcomputation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary action by pre-generating a comprehensive training dataset from high-fidelity physics simulations before the actual optimization process. This upfront investment in creating a robust surrogate model allows subsequent design evaluations to be performed rapidly. The surrogate model captures the complex physics relationships in advance, enabling fast predictions during the optimization iterations without repeatedly running expensive simulations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces a surrogate model as an intermediary between the design parameters and the physics-based validation requirements. Instead of directly running expensive MCNP and thermal-stress simulations for each design evaluation, the surrogate model mediates by providing rapid predictions of key performance metrics. This intermediary layer filters and approximates the complex physics computations, enabling fast design exploration while maintaining reasonable accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If exhaustive design space exploration is performed to find global optimal solutions, then manufacturing precision is improved, but productivity deteriorates due to the vast number of required evaluations

Engineering Contradiction:
Improveoptimal design parameter identificationVSAvoiddesign space exploration speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent implements feedback through the optimization algorithm that uses surrogate model predictions to guide the search for optimal designs. The algorithm learns from previous evaluations, identifying promising regions of the design space and focusing computational resources there. This feedback mechanism allows the system to converge to high-quality solutions much faster than exhaustive grid searches, adapting the exploration strategy based on accumulated knowledge from prior evaluations.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent employs dynamic optimization strategies where the search methodology adapts during the design exploration process. The algorithm dynamically adjusts sampling density, exploration vs. exploitation balance, and parameter ranges based on feedback from surrogate model evaluations. This dynamic approach allows efficient navigation of the design space, concentrating computational effort on regions likely to contain optimal solutions rather than uniformly sampling the entire space.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS12001766B2Optimization of expensive cost functions subject to complex multidimensional constraints
Publication Date: 2024.06.04 BWXT ADVANCED TECHNOLOGIES LLC
  • US12001766B2 patent drawing
  • US12001766B2 patent drawing
  • US12001766B2 patent drawing

AI summary

A method is used to design nuclear reactors using design variables and metric variables. A user specifies ranges for the design variables and target values for the metric variables. A set of design parameter samples are selected. For each sample, the method runs three processes, which compute metric variables to thermal-hydraulics, neutronics, and stress. The method applies a cost function to each sample to compute an aggregate residual of the metric variables compared to the target values. The method trains a machine learning model using the samples and the computed aggregate residuals. The method shrinks the range for each design variable according to correlation between the respective design variable and estimated residuals using the machine learning model. These steps are repeated until a sample having a smallest residual is unchanged for multiple iterations. The method then uses the final machine learning model to assess relative importance of each design variable.