Nuclear Waste Container Drying with Controlled Inert Gas Purging

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Solution Overview

Problem

Existing methods for drying transport and storage containers for nuclear waste are complex, costly, and have insufficient drying efficiency, especially for containers with high thermal output.

Innovation Solution

A method involving draining or pumping out residual water, evacuating the container interior, and then introducing inert gas such as helium while controlling the gas content to maintain a specific volume percentage, which includes a first evacuation phase followed by continuous evacuation and helium introduction to achieve a desired dryness level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional drying methods are used, then drying can be achieved, but the process is complex and costly

Engineering Contradiction:

Improvedrying process simplicityVSAvoiddrying equipment complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent applies inert atmosphere by introducing nitrogen gas into the container to create an oxygen-free environment. This prevents oxidation of nuclear fuel rod cladding during the drying process while simplifying the overall system by eliminating the need for complex vacuum drying equipment. The nitrogen atmosphere allows for effective drying through controlled evaporation without requiring sophisticated vacuum systems.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Productivity

If conventional drying methods are used, then drying can be achieved, but drying efficiency is insufficient for high thermal output containers

Engineering Contradiction:

Improvedrying efficiencyVSAvoidcontainer thermal output

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent changes the atmospheric parameters by introducing nitrogen gas at controlled flow rates and maintaining specific pressure conditions. This creates optimal conditions for rapid evaporation of residual water from the container interior. The nitrogen atmosphere allows for higher temperatures to be maintained without oxidation risks, significantly improving drying efficiency for containers with high thermal output from nuclear fuel rods.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements continuous nitrogen gas flow throughout the drying process, ensuring constant replacement of water vapor with dry nitrogen. This continuous action maintains optimal drying conditions throughout the container interior, preventing re-condensation and ensuring efficient removal of moisture even in containers with high thermal output that generate significant evaporation rates.

Inventive Principle:

Principle #20Continuity of useful action

3Loss of time

If vacuum drying is used, then water removal can be achieved, but the process is time-consuming

Engineering Contradiction:

Improvedrying timeVSAvoiddrying speed

Core Design Contradiction:

Loss of timeVSProductivity

Solution Approach 1:

The patent replaces vacuum drying with inert atmosphere drying using nitrogen gas. This method achieves faster drying times by introducing nitrogen at controlled flow rates that directly displace water vapor from the container interior. The inert atmosphere prevents oxidation while enabling rapid moisture removal through continuous gas flow, significantly reducing the drying time compared to traditional vacuum methods.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

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 method enables efficient, simple, and inexpensive drying of containers with high thermal output, characterized by high functional reliability and low equipment costs, suitable for containers with high heat outputs.

Implementation Method 1

evacuating gas from the interior of the drained or pumped out container

Methodology Applied

Scientific EffectVacuum: Vacuum

Implementation Method 2

feeding an inert gas into the drained or pumped out container interior while continuing to evacuate gas from the container interior

Methodology Applied

Scientific EffectGas diffusion and mixing: Diffusion

Data Source

PatentUS11639827B2Method of drying a transport and storage container

Publication Date: 2023.05.02 GNS GESELLSCHAFT FUR NUKLEAR SERVICE MBH

AI summary

A method of drying transport and/or storage containers for radioactive waste has the first step draining or pumping residual water out of the container holding the nuclear waste. Then gas is evacuated from the interior of the drained or pumped out container interior. Thereafter an inert gas is fed into the drained or pumped out container interior while continuing to evacuate gas from the container interior. During the evacuation and/or infeeding of inert gas a rate of evacuation and/or a rate of infeed of the inert gas is controlled such such that an inert-gas content in the interior of the container is between 50 and 95 vol %.