High-Density Subterranean Nuclear Waste Storage Using Thermosyphon Cooling
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Solution Overview
Problem
Existing underground nuclear waste storage systems face inefficiencies in space utilization and ventilation, leading to rapid capacity saturation and inadequate cooling of radioactive waste due to fluid coupling between modules, resulting in uneven air distribution and pressure imbalances.
Innovation Solution
A passively ventilated underground storage system using cavity enclosure containers (CECs) with direct air inlet coupling to ambient air feeder shells, employing a natural convective thermo-siphon effect for cooling, and avoiding direct fluid connections between CECs to ensure uniform air distribution and efficient heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple storage modules are fluidly coupled to a common ventilation system, then space utilization is improved, but air distribution becomes uneven and pressure imbalances occur
Solution Approach 1:
The ventilation system is segmented into independent zones, with each storage module having its own dedicated air inlet and outlet. This segmentation prevents fluid coupling between modules while maintaining individual cooling efficiency, resolving the pressure imbalance issue while preserving space utilization benefits.
Solution Approach 2:
A common plenum chamber serves as an intermediary structure that distributes air to multiple storage modules without creating direct fluid coupling. The plenum chamber acts as a pressure equalization zone, ensuring uniform air distribution to each module while allowing compact spatial arrangement.
2Productivity
If storage modules are arranged densely to maximize capacity, then productivity is improved, but ventilation efficiency deteriorates
Solution Approach 1:
The ventilation system transitions from horizontal air distribution to vertical airflow patterns. Air enters through lower inlets and exits through upper outlets, utilizing vertical dimension for heat rise and air movement. This allows dense horizontal packing of modules while maintaining effective cooling through vertical thermal convection currents.
Solution Approach 2:
The storage modules utilize natural buoyancy-driven convection currents for self-cooling. Heated air naturally rises and exits through upper outlets, creating self-sustaining airflow patterns without requiring complex forced ventilation systems. This passive cooling mechanism maintains efficiency even in densely packed configurations.
3Use of energy by moving object
If natural convective cooling is used without fans, then energy consumption is reduced, but air flow control becomes insufficient
Solution Approach 1:
The system optimizes geometric parameters of air inlets and outlets, including their sizes, positions, and orientations, to maximize natural convective airflow. By carefully designing these parameters, sufficient air flow is achieved through passive convection alone, eliminating the need for energy-consuming fans while maintaining adequate cooling control.
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 maximizes storage capacity and ensures uniform cooling of nuclear waste canisters, maintaining structural integrity and safety by preventing air pressure imbalances and ensuring adequate ventilation without the need for fans or blowers.
Implementation Method 1
employing a natural convective thermo-siphon effect for cooling
Implementation Method 2
A passively ventilated underground storage system using cavity enclosure containers (CECs) with direct air inlet coupling to ambient air feeder shells, employing a natural convective thermo-siphon effect for cooling
Data Source
AI summary
A passively cooled stackable nuclear waste storage system includes an at least partially below grade cavity enclosure container (CEC) and above grade cask. Each vessel includes a cavity holding a nuclear waste canister containing spent nuclear fuel or other high-level radioactive wastes. The CEC is founded on a below grade concrete base pad and cask is mounted on an above-grade concrete top pad in a vertically stacked arrangement. The upper cask comprises a perforated baseplate which establishes fluid communication between cavities of both casks and is configured to prevent radiation shine. One or both vessels include air inlets which draw ambient cooling air into their respective cavities for cooling the nuclear waste. Air heated in the lower CEC rises into the upper cask through the baseplate where it mixes with air drawn into the cask and is returned to atmosphere. The system increases storage capacity of new or existing facilities.