Below-Grade Radioactive Waste Ventilation System
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Solution Overview
Problem
Current dry storage systems for high-level radioactive waste face challenges in ensuring safety against both human-induced threats and natural disasters, particularly in terms of community acceptance and the potential for radioactive material release during catastrophic events.
Innovation Solution
A ventilated system for storing high-level radioactive waste is designed with a below-grade assembly comprising air-intake and storage shells, a network of pipes for distinct air-delivery passageways, and hermetically sealed containers, utilizing natural ventilation and radiation shielding to prevent radioactive material release and enhance safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If used nuclear fuel is stored in fuel pools, then cooling is provided, but structural damage and loss of cooling can occur during natural disasters
Solution Approach 1:
The patent replaces the active mechanical cooling system of fuel pools with a passive dry storage system that uses natural convection and conduction through the cask structure and surrounding soil/rock to dissipate heat, eliminating the need for pumps, pipes, and electrical systems that can fail during disasters
Solution Approach 2:
The patent uses an inert gas atmosphere (typically nitrogen or helium) within the dry storage cask to prevent oxidation and corrosion of the fuel cladding, while the cask is surrounded by additional inert or protective materials to prevent water ingress and chemical reactions during flood or earthquake events
2Strength
If dry storage casks are placed above-grade, then structural resistance is improved, but community acceptance and security concerns worsen
Solution Approach 1:
The patent transitions from above-grade surface storage to below-grade subsurface storage, utilizing the vertical dimension and earth/rock cover to provide passive radiation shielding, physical protection from unauthorized access, and aesthetic integration with the landscape, thereby addressing community concerns while maintaining security
Solution Approach 2:
The patent introduces multiple intermediate containment structures including the dry storage cask itself, overpack containers, and the surrounding earth/rock formation as intermediary barriers between the radioactive fuel and the environment, providing layered protection and reducing perceived risk to the public
3Reliability
If multiple air-delivery passageways are provided for each storage cavity, then ventilation reliability is improved, but system complexity increases
Solution Approach 1:
The patent divides the ventilation system into multiple independent air-delivery passageways for each storage cavity, allowing individual cavities to be ventilated through separate pathways, which isolates potential blockages or failures to specific segments rather than affecting the entire system
Solution Approach 2:
The patent incorporates air-delivery passageways and ventilation channels into the structural design of the storage shells and surrounding medium during construction, rather than adding them as separate installed components, thereby simplifying the overall system while ensuring reliable ventilation pathways are established beforehand
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 system effectively prevents radioactive material release during disasters and enhances community acceptance by providing a secure, safe, and environmentally isolated storage solution for high-level radioactive waste, leveraging natural ventilation and radiation shielding.
Implementation Method 1
A ventilated system for storing high-level radioactive waste is designed with a below-grade assembly comprising air-intake and storage shells, a network of pipes for distinct air-delivery passageways
Implementation Method 2
utilizing natural ventilation and radiation shielding to prevent radioactive material release and enhance safety
Data Source
AI summary
A ventilated system for storing high level radioactive waste, such as used nuclear fuel, in a below-grade environment, in one embodiment, the invention is a ventilated system comprising an air-intake shell and a plurality of storage shells that are interconnected by a network of pipes configured to achieve double redundancy and/or improved air delivery. In another embodiment, the invention is a ventilated system that utilizes a mass of low level radioactive waste contained in a hermetically sealed enclosure cavity, the low level radioactive waste providing radiation shielding for high level radioactive waste stored in a storage cavity of said ventilated system.