Passive Spent Fuel Pool Cooling via Thermal Conduction
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Solution Overview
Problem
Conventional active spent fuel pool cooling systems in nuclear reactors rely on alternating current power, making them vulnerable in the event of a loss of onsite and offsite power, which can lead to unsafe conditions due to uncontrolled decay heat generation.
Innovation Solution
A passive cooling system is introduced, featuring a gap along the periphery of the spent fuel pool filled with water during emergencies, utilizing thermal conductive members to transfer heat to a heat sink, such as a mass of earth or concrete, with a thermal switch mechanism to activate water flow only in the absence of power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an active spent fuel pool cooling system is used, then cooling effectiveness is improved, but vulnerability to power loss increases
Solution Approach 1:
The passive cooling system utilizes natural convection and thermal conduction through the pool wall to remove decay heat without requiring external power sources. The system serves itself by leveraging the temperature differential between the hot spent fuel and the ambient environment, eliminating dependence on powered equipment during power outages.
Solution Approach 2:
The invention replaces the active mechanical cooling system (pumps, fans, powered heat exchangers) with a passive thermal conduction system. Heat is removed through the pool wall structure itself via thermal conduction, substituting mechanical power-dependent components with a physics-based passive heat transfer mechanism.
2Object-affected harmful factors
If a passive cooling system is introduced, then power loss vulnerability is reduced, but heat transfer efficiency may worsen
Solution Approach 1:
The pool wall structure is pre-configured with thermal conduction pathways and heat sink capabilities before a power loss event occurs. The passive cooling system is designed in advance with appropriate thermal mass and conduction paths to ensure effective heat removal when activated, eliminating the need for active components that would reduce efficiency.
Solution Approach 2:
The invention utilizes composite construction of the spent fuel pool wall, combining materials with high thermal conductivity (such as steel liners) with thermal mass materials (such as concrete or earth berms). This composite structure optimizes both the passive heat conduction pathway and the heat sink capacity, maintaining effective heat transfer without external power.
3Reliability
If the pool wall structure is modified to enable passive cooling, then cooling capability is improved, but structural complexity increases
Solution Approach 1:
The pool wall structure serves multiple functions: it contains the water, provides radiation shielding, and acts as the primary heat conduction pathway for passive cooling. By integrating the thermal management function into the existing structural wall rather than adding separate cooling infrastructure, the invention avoids increasing overall system complexity.
Solution Approach 2:
The invention merges the structural support function with the thermal conduction function by utilizing the pool wall itself as the heat transfer pathway. Rather than adding separate passive cooling components, the wall structure is designed to perform both mechanical containment and thermal management roles simultaneously.
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 system effectively removes decay heat from the spent fuel pool without the need for external power, ensuring safe temperature regulation and preventing water boiling, even during prolonged power outages by leveraging the higher conductivity of water to enhance heat transfer.
Implementation Method 1
the one or more members are structured to transport heat from the gap to the heat sink
Implementation Method 2
a thermal switch mechanism having an activate position and a deactivate position which is structured to deliver water from the water system into the gap when in the activate position
Data Source
AI summary
The present invention relates to passive cooling systems and methods for cooling a spent fuel pool in a nuclear power plant in the absence of onsite and offsite power, e.g., in a station blackout event. The systems include a gap formed along the periphery of the spent fuel pool, a heat sink, one or more thermal conductive members, a water supply system for delivering water to at least partially fill the gap and conduct heat generated from the spent fuel pool through the gap to at least one thermal conductive member for transporting heat to the heat sink, and a thermal switch mechanism for activating and deactivating the water supply system.In particular, the passive spent fuel pool cooling systems and methods of the invention are useful when the active spent fuel pool cooling system is unavailable or inoperable.