SiC Composite BWR Channel Boxes With Metallic Corrosion Barriers

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Solution Overview

Problem

Zirconium alloys used in channel boxes of boiling water reactors (BWRs) experience anisotropic growth, corrosion, and hydrogen pickup, leading to distortion and potential cracking, which interferes with control blade operation and poses safety risks.

Innovation Solution

A channel box comprising a substrate of silicon carbide fibers infiltrated with silicon carbide and coated with a corrosion-resistant metallic layer, such as zirconium or titanium alloys, to resist distortion and corrosion, with optional pre-irradiation to uniform radiation exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If zirconium or zirconium alloy is used for channel boxes, then corrosion resistance is improved, but radiation-induced anisotropic growth and distortion occur

Engineering Contradiction:

Improvecorrosion resistanceVSAvoiddistortion

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The patent uses a composite structure consisting of a silicon carbide fiber substrate infiltrated with silicon carbide matrix, coated with a corrosion-resistant metallic layer. This composite material combines the dimensional stability of silicon carbide under radiation with the corrosion resistance of metallic coatings, resolving the contradiction between maintaining shape stability and achieving corrosion resistance.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the material parameters by selecting silicon carbide fibers with specific crystal orientations and controlling the infiltration process to achieve uniform microstructure. This parameter control minimizes anisotropic growth characteristics while maintaining the material's inherent resistance to radiation-induced distortion.

Inventive Principle:

Principle #35Parameter changes

2Strength

If zirconium channel boxes are used, then structural strength is maintained, but hydrogen pickup and corrosion susceptibility increase

Engineering Contradiction:

Improvestructural strengthVSAvoidhydrogen pickup

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a metallic coating layer as an intermediary between the silicon carbide substrate and the reactor environment. This coating layer acts as a barrier that prevents hydrogen pickup and corrosion while allowing the silicon carbide substrate to maintain its structural strength, thus resolving the contradiction between strength and hydrogen susceptibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Shape

If pre-irradiation is applied to channel boxes, then non-uniform swelling is reduced, but additional manufacturing complexity is introduced

Engineering Contradiction:

Improveuniform swellingVSAvoidmanufacturing complexity

Core Design Contradiction:

ShapeVSEase of manufacture

Solution Approach 1:

The patent applies pre-irradiation treatment to the channel boxes before they are installed in the reactor. This preliminary exposure to controlled radiation doses induces uniform swelling and stabilizes the dimensional characteristics of the silicon carbide composite, preventing non-uniform distortion during actual reactor operation. The manufacturing complexity is managed through standardized pre-irradiation facilities and process control.

Inventive Principle:

Principle #10Preliminary action

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 solution provides enhanced resistance to distortion and corrosion, improving the safety and operational stability of BWRs by minimizing zirconium content and reducing the risk of hydrogen-induced explosions.

Implementation Method 1

Each side of the channel box has been exposed to at least one displacements per atom of radiation

Methodology Applied

Scientific EffectRadiation-induced swelling: Radiation

Implementation Method 2

the first layer comprises a corrosion resistant metallic composition

Methodology Applied

Scientific EffectCorrosion resistance:

Data Source

PatentUS12633425B2Channel boxes for a boiling water reactor and methods of manufacture thereof

Publication Date: 2026.05.19 WESTINGHOUSE ELECTRIC CORP

AI summary

A BWR channel box comprises a substrate, a first layer, and a second layer. The substrate comprises silicon carbide fibers. The first layer is deposited on a first surface of the substrate. The second layer is deposited on an opposite second surface of the substrate. Each layer comprises a corrosion resistant metallic composition. The combined weight of both layers is in a range from greater than 0% to 10% of the total weight of the channel box.