Drying Apparatus for Spent Nuclear Fuel Canisters
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Solution Overview
Problem
Current methods for drying canisters loaded with spent nuclear fuel are time-consuming, prone to errors, and risk contamination, as they require manual vacuum monitoring and create sub-atmospheric conditions, which can be hazardous and costly. Additionally, existing radiation shielding geometries are cumbersome and apply excessive load on target pipes, affecting durability.
Innovation Solution
A drying apparatus with separate non-contaminated and contaminated non-reactive gas circulation systems, controlled by a radiation dosimeter to prevent contamination and efficiently dry canisters, combined with a radiation shielding geometry that can adjust thickness and be self-supported, allowing accurate radiation dose rate measurement without stressing the target pipe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual vacuum monitoring and sub-atmospheric conditions are used for drying canisters, then drying effectiveness is improved, but contamination risk and operational complexity increase
Solution Approach 1:
The gas circulation system is divided into separate contaminated and non-contaminated circulation paths. The contaminated circulation path handles gas that has contacted the canister interior during drying, routing it through filtration and cooling before disposal or recirculation. The non-contaminated path handles fresh gas supply and clean return flow. This segmentation prevents cross-contamination while maintaining effective drying conditions without requiring complex manual vacuum monitoring procedures.
Solution Approach 2:
A radiation dosimeter is introduced as an intermediary device to automatically monitor radiation levels and control the drying process. The dosimeter detects radiation from the spent nuclear fuel and provides feedback to the control system, enabling automatic adjustment of gas circulation rates and temperature control. This eliminates the need for manual vacuum monitoring while maintaining drying effectiveness and reducing operational complexity.
2Measurement precision
If radiation dosimeter is installed directly on target pipe for measurement, then measurement accuracy is improved, but pipe stress and durability concerns increase
Solution Approach 1:
The radiation dosimeter is extracted from direct contact with the target pipe and relocated to a separate mounting position. The dosimeter is positioned to face the pipe through a defined geometric relationship, allowing accurate radiation measurement without physical attachment to the pipe. This extraction eliminates mechanical stress on the pipe while maintaining measurement precision through controlled geometric positioning and radiation shielding calculations.
3Ease of manufacture
If fixed thickness radiation shielding is used, then manufacturing simplicity is improved, but adaptability to different radiation levels decreases
Solution Approach 1:
The radiation shielding geometry is designed with dynamic adjustability, allowing the shielding thickness and configuration to be modified based on measured radiation dose rates. The system includes adjustable shielding components that can be positioned at different distances from the dosimeter or varied in thickness according to the specific radiation environment. This dynamic capability enables the same shielding geometry to adapt to different radiation levels while maintaining manufacturing simplicity through modular design elements.
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 apparatus prevents contamination by using appropriate gas circulation systems based on radiation dose rate measurements and ensures accurate radiation shielding without applying excessive load on pipes, enhancing safety and durability during spent nuclear fuel storage and transport.
Implementation Method 1
a radiation dosimeter which is installed outside the second gas circulation line between the canister and the branched valve member to measure a radiation dose rate of the non-reactive gas which is discharged from the canister
Implementation Method 2
a heater which is mounted on the first gas circulation line between the valve member and the canister to heat the non-reactive gas to be supplied to the canister
Implementation Method 3
a gas cooling unit which is fluidly coupled to the canister through a second gas circulation line to cool the non-reactive gas discharged from the cavity of the canister
Implementation Method 4
a dew point temperature measuring member which is mounted on a third gas circulation line, which connects the gas cooling unit and the reactive gas source to communicate each other, to repeatedly measure a dew point temperature of the non-reactive gas
Data Source
AI summary
The present invention relates to a drying apparatus for drying a canister configured to transport and store spent nuclear fuels, a control method thereof, and a radiation shielding geometry for a radiation dosimeter configured to measure a radiation dose rate. An object of the present invention is to prevent a drying apparatus from being contaminated even in case of a damaged canister loaded with a spent nuclear fuel, by providing a non-contaminated circulation system and a contaminated circulation system, to easily assemble the drying apparatus to have a proper thickness depending upon a radiation dose rate, and to prevent a facility pipeline from being under stress by providing a radiation shielding geometry for a radiation dosimeter for measuring a radiation dose rate.