Custom Fuel Assembly Layout for SMR Reactivity and Neutron Control

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Solution Overview

Problem

Existing methods for designing new fuel assemblies for nuclear reactors, particularly for smaller Modular Reactors (SMR), are limited in controlling and optimizing the operation due to the use of existing fuel assembly concepts with fixed numbers and locations of fuel rods and thimbles, leading to reduced flexibility and efficiency.

Innovation Solution

A method for building a new fuel assembly that determines the number and positions of spacer grid cells, fuel rods, thimble tubes, and their receiving means based on specific parameters of the new nuclear reactor, using calculation programs to optimize neutron leakage, reactivity control, and power distribution, allowing for customized designs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If existing fuel assembly concepts with fixed numbers and locations of fuel rods and thimbles are used, then manufacturing and assembly processes are simplified, but flexibility and efficiency in controlling and optimizing reactor operation are reduced

Engineering Contradiction:
Improveflexibility in controlling and optimizing reactor operationVSAvoidcomplexity in determining and positioning fuel rods and thimbles
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the fuel assembly configuration adaptable and adjustable rather than fixed. The method enables dynamic optimization of reactor operation by allowing the numbers and positions of fuel rods and thimbles to be determined based on specific reactor parameters and operational requirements, rather than being constrained by existing fixed designs.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by determining the numbers and positions of fuel rods and thimbles based on specific parameters of the new nuclear reactor. This allows optimization of operational characteristics such as neutron leakage, reactivity control, and power distribution by adjusting configuration parameters rather than using fixed designs.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If customized fuel assemblies are designed for specific reactor parameters, then operational efficiency and control are improved, but design and manufacturing complexity increases

Engineering Contradiction:
Improveefficiency in fuel use and coolingVSAvoidease of building fuel assembly
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by determining the numbers and positions of fuel rods and thimbles in advance based on specific reactor parameters before actual assembly. This preliminary design phase allows optimization of operational efficiency while streamlining the subsequent manufacturing and assembly processes by having all configuration decisions made beforehand.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements universality by creating a versatile design method that can be applied to different nuclear reactor types and configurations. The same general approach of determining fuel rod and thimble arrangements based on specific parameters can be universally applied across various reactor designs, maintaining ease of manufacture while achieving customization.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If the numbers and positions of fuel rods and thimbles are optimized based on reactor parameters, then neutron leakage and power distribution are improved, but the design process becomes more complex

Engineering Contradiction:
Improveneutron leakage control and reactivity controlVSAvoidcomplexity in determining configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies feedback by using an iterative design process where the numbers and positions of fuel rods and thimbles are determined based on reactor parameters, with optimization of neutron leakage and power distribution achieved through calculated arrangements. The receiving means are positioned to provide proper support and alignment, creating a feedback loop between configuration design and operational performance.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent implements local quality by optimizing specific local arrangements of fuel rods and thimbles based on their positions within the reactor core. Different regions of the fuel assembly can have different configurations tailored to local requirements for neutron leakage control and power distribution, rather than using uniform arrangements throughout.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP4675645A1A method for building a new fuel assembly, a new fuel assembly and a new nuclear reactor
Publication Date: 2026.01.07 WESTINGHOUSE ELECTRIC SWEDEN AB
  • EP4675645A1 patent drawingFigure 1
  • EP4675645A1 patent drawingFigure 2
  • EP4675645A1 patent drawingFigure 3

AI summary

A method (100) for building a new fuel assembly (1) is described. The method (100) comprises: determining (101) at least one parameter characteristic of a new reactor (13), determining (103) a first number of spacer grid cells (5) and corresponding first number of fuel rods (7), determining a second number of thimble tubes (9) and corresponding second number of receiving means (11), and positions of the receiving means (11) in relation to the spacer grids cells (5) within the spacer grid (3). The method comprises: assembling (105) at least one the new spacer grid (3), mounting (107) each of the second number of thimble tubes (9) in respective receiving means (11) of the second number of receiving means (11) within the at least one spacer grid (3) and loading (109) each of the first number of fuel rods (7) into respective spacer grid cell (5). A new fuel assembly (1) and a new nuclear reactor (13) are also described.