Doppler Reactivity Augmentation Device for Fast Neutron Core Stability

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Solution Overview

Problem

Fast neutron reactors face challenges in maintaining reactor core stability and efficient thermal generation due to the high burnup and energy intensity, which stresses structural materials and affects reactivity coefficients.

Innovation Solution

Incorporating Doppler reactivity augmentation devices made of vanadium or vanadium alloys into the nuclear reactor core, which amplify the negativity of the Doppler reactivity coefficient and reduce the coolant temperature coefficient, thereby enhancing stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If high burnup and energy intensity are used in fast neutron reactors, then power output and energy generation efficiency are improved, but reactor core stability deteriorates due to increased stress on structural materials and reactivity coefficients

Engineering Contradiction:

Improvepower outputVSAvoidreactor core stability

Core Design Contradiction:

PowerVSStability of the object's composition

Solution Approach 1:

The patent introduces Doppler reactivity augmentation devices that provide negative feedback to stabilize the reactor core. These devices amplify the negative Doppler reactivity coefficient, creating a self-regulating mechanism where temperature increases automatically reduce reactivity, preventing runaway reactions and maintaining core stability under high power conditions

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent modifies the reactivity parameters of the reactor core by inserting Doppler reactivity augmentation devices. These devices change the Doppler reactivity coefficient and coolant temperature coefficient parameters, transforming the reactor's response characteristics to maintain stability while operating at high power levels

Inventive Principle:

Principle #35Parameter changes

2Productivity

If high burnup and energy intensity are used in fast neutron reactors, then energy generation efficiency is improved, but structural materials experience increased stress and reduced integrity

Engineering Contradiction:

Improveenergy generation efficiencyVSAvoidstructural material integrity

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The Doppler reactivity augmentation devices create a feedback mechanism that limits temperature excursions and prevents excessive thermal stress on structural materials. By automatically reducing reactivity when temperature rises, the system protects structural integrity while maintaining high energy generation efficiency through controlled operation

Inventive Principle:

Principle #23Feedback

3Stability of the object's composition

If Doppler reactivity augmentation devices are inserted into the reactor core, then reactor core stability is improved through enhanced negative Doppler coefficient, but device complexity increases

Engineering Contradiction:

Improvereactor core stabilityVSAvoidreactor core structure

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The Doppler reactivity augmentation devices serve multiple functions: they provide stability control through enhanced negative Doppler feedback, act as structural support elements within the fuel assembly, and can be integrated with existing reactor components. This multi-functionality reduces the need for separate dedicated stability control systems

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent applies Doppler reactivity augmentation locally within specific fuel assemblies rather than throughout the entire reactor core. This targeted approach provides stability enhancement where most needed while minimizing the overall complexity and material consumption of the reactor structure

Inventive Principle:

Principle #3Local quality

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

The implementation of Doppler reactivity augmentation devices leads to a more stable nuclear reactor core by increasing the negative Doppler reactivity coefficient and decreasing the coolant temperature coefficient, ensuring enhanced operational stability and efficiency.

Implementation Method 1

amplify the negativity of the Doppler reactivity coefficient

Methodology Applied

Scientific EffectDoppler broadening: Doppler Effect

Implementation Method 2

Doppler reactivity augmentation devices that amplify the negativity of the Doppler reactivity coefficient

Methodology Applied

Scientific EffectNeutron scattering: Scattering

Implementation Method 3

Liquid coolant flows through the reactor core, absorbing thermal energy from the nuclear fission reactions

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20250079027A1Doppler reactivity augmentation device

Publication Date: 2025.03.06 TERRAPOWER LLC

AI summary

A fast neutron nuclear reactor contains a nuclear reactor core having an array of device locations. Some device locations in the nuclear reactor core contain fissile and fertile nuclear fuel assembly devices. One or more other device locations in the nuclear reactor core contain Doppler reactivity augmentation devices that amplify the negativity of the Doppler reactivity coefficient within the nuclear reactor core. In some implementations, a Doppler reactivity augmentation device can also reduce the coolant temperature coefficient within the nuclear reactor core. Accordingly, a Doppler reactivity augmentation device contributes to a more stable nuclear reactor core.