RTG-Powered Cooling for Spent Nuclear Fuel Casks

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Solution Overview

Problem

Current dry storage systems for spent nuclear fuel face challenges in efficiently dissipating heat generated by radioactive decay, which limits their ability to quickly transition from wet to dry storage and store fuel for extended periods.

Innovation Solution

A cooling system integrated into cask designs that utilizes a radioisotope thermoelectric generator (RTG) to convert heat from spent nuclear fuel into electricity, powering a compressor, fan, or pump to force coolant circulation, enhancing heat transfer and allowing for the use of less expensive coolants like nitrogen gas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If passive heat dissipation is used in dry storage systems, then system complexity is reduced, but heat dissipation efficiency is insufficient

Engineering Contradiction:

Improvecooling system complexityVSAvoidheat dissipation efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The system uses the spent fuel's own radioactive decay heat to power the cooling system through an RTG, creating a self-service mechanism where the heat source also provides the energy for cooling. This resolves the contradiction by maintaining low external complexity while achieving active cooling efficiency.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces passive thermal conduction with an active thermoelectric generation system that converts heat directly to electricity to drive cooling components. This substitution enables efficient heat dissipation while maintaining system simplicity through direct energy conversion rather than complex mechanical arrangements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If expensive coolants are used, then heat transfer efficiency is improved, but cost increases

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidcost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The RTG-powered cooling system enables the use of cheaper coolants by providing sufficient active cooling capacity to compensate for their lower inherent heat transfer properties. The system serves itself by using radioactive decay heat to drive the cooling, allowing cost-effective coolant selection without sacrificing efficiency.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention changes the operational parameters of the cooling system from passive to active, enabling the use of different coolant types with varying thermal properties. This parameter change allows selection of less expensive coolants while maintaining effective heat dissipation through controlled circulation.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If wet storage is used for extended periods, then cooling capability is maintained, but radiation exposure and operational time increase

Engineering Contradiction:

Improvecooling capabilityVSAvoidstorage time

Core Design Contradiction:

TemperatureVSLoss of time

Solution Approach 1:

The patent substitutes water-based wet storage cooling with an active gas cooling system powered by RTG. This substitution enables effective cooling in dry storage, allowing earlier transition from wet to dry storage and reducing the time spent in high-radiation wet storage environments.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The RTG acts as an intermediary that converts radioactive decay heat into electrical power to drive the cooling system. This intermediary mechanism enables cooling capability in dry storage without requiring extended wet storage periods, thereby reducing radiation exposure time.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This solution enables more efficient heat dissipation, allowing for earlier transition to dry storage, increased fuel load capacity, and cost savings by reducing radiation exposure and equipment operation time, while providing a self-regulating cooling mechanism.

Implementation Method 1

A cooling system integrated into cask designs that utilizes a radioisotope thermoelectric generator (RTG) to convert heat from spent nuclear fuel into electricity

Methodology Applied

Scientific EffectSeebeck effect: Seebeck Effect

Implementation Method 2

enhancing heat transfer

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 3

force coolant circulation

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS9911516B2Cooling systems for spent nuclear fuel, casks including the cooling systems, and methods for cooling spent nuclear fuel

Publication Date: 2018.03.06 GE HITACHI NUCLEAR ENERGY AMERICAS LLC

AI summary

A cooling system for spent nuclear fuel may include a device configured to generate electricity using energy emitted from the spent nuclear fuel. The cooling system may be configured to use the electricity when cooling the spent nuclear fuel. A cask for storage, transport, or storage and transport of spent nuclear fuel may include the cooling system and a container configured to hold the spent nuclear fuel. A method for cooling spent nuclear fuel may include generating electricity using energy emitted from the spent nuclear fuel, and using the electricity in a cooling system for the spent nuclear fuel when cooling the spent nuclear fuel.