Ventilated Storage System Throttle for Radioactive Waste Temperature Control
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Solution Overview
Problem
Stress Corrosion Cracking (SCC) of stainless steel nuclear waste canisters in coastal environments due to surface temperature changes and corrosive elements, and degradation of concrete storage systems from freeze-thaw cycles, which compromise structural integrity and radiation shielding.
Innovation Solution
A ventilated storage system with a throttle mechanism to control airflow through the ventilation passageway, maintaining the canister and concrete surface temperatures above critical thresholds to prevent SCC and freezing, using natural convective flow to adjust heat rejection rates in response to decreasing heat generation rates of radioactive waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If natural convective flow is used for cooling, then equipment complexity is reduced, but temperature control precision deteriorates
Solution Approach 1:
The invention introduces a movable baffle that can dynamically adjust the airflow path and ventilation area in response to changing heat generation rates of the radioactive waste. This dynamic adjustment mechanism allows the passive cooling system to maintain optimal temperature control without requiring complex active cooling equipment, thus resolving the contradiction between simplicity and temperature control precision.
Solution Approach 2:
The baffle's position changes the ventilation parameters (airflow rate, flow path length) as the heat generation rate decreases over time. By changing the physical parameter of the ventilation area, the system adapts to varying thermal conditions while maintaining a simple passive cooling architecture, addressing both simplicity and temperature control requirements.
2Reliability
If ventilation is increased to prevent SCC, then reliability improves, but heat rejection increases causing excessive cooling
Solution Approach 1:
The movable baffle dynamically adjusts the ventilation area based on the heat generation rate, which decreases over time. When heat generation is high, larger ventilation prevents SCC; when heat generation decreases, the baffle reduces ventilation area to maintain optimal temperature. This dynamic adaptation resolves the contradiction between preventing SCC and avoiding excessive cooling.
Solution Approach 2:
The baffle is pre-positioned to provide maximum ventilation when the canister is first placed, preventing SCC from the outset. As the radioactive waste cools over time, the baffle is gradually adjusted to reduce ventilation, preventing the system from entering a state of excessive cooling. This preliminary and progressive adjustment strategy resolves the contradiction between immediate SCC prevention and long-term temperature maintenance.
3Ease of operation
If passive cooling is used, then ease of operation improves, but adaptability to changing heat generation rates deteriorates
Solution Approach 1:
The invention transforms a static passive cooling system into a dynamic one by introducing a movable baffle. The baffle can be adjusted in response to changing heat generation rates, providing adaptability while maintaining the simplicity of passive cooling operation. The system remains easy to operate (no active cooling equipment needed) but gains the ability to adapt to varying thermal conditions through the adjustable baffle configuration.
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
Prevents SCC and concrete degradation by maintaining surface temperatures above deliquesce and freezing thresholds, ensuring long-term structural integrity and radiation shielding effectiveness.
Implementation Method 1
heat generated by the radioactive waste causes a natural convective flow of air through a ventilation passageway of the storage system
Implementation Method 2
throttling the natural convective flow of the air through the ventilation passageway to maintain a portion of the storage system at a temperature within a predetermined range
Data Source
AI summary
A system and method for storing radioactive waste, such as spent nuclear fuel, in one embodiment, the invention is a method of controlling temperature of a portion of a storage system comprising a container loaded with radioactive waste and a ventilated module in which the container is positioned, the ventilated module configured so that heat generated by the radioactive waste causes a natural convective flow of air through, a ventilation passageway of the ventilated module, the method comprising; throttling the natural convective flow of the air through the ventilated module to alter a heat rejection rate of the storage system to compensate for a decreasing heat generation rate of the radioactive waste to maintain the portion of the storage system within a predetermined temperature range.