Passive Reactor Heat Removal with Fluidic Diode Bypass Cooling
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Solution Overview
Problem
Current nuclear reactors face challenges in effectively managing residual decay heat during shutdown and startup processes, as existing safety systems are not designed to handle heat removal during these phases efficiently, potentially leading to catastrophic failures.
Innovation Solution
A passive heat removal system utilizing natural circulation and a fluidic diode to facilitate heat transfer between a hot leg and a cold leg of an intermediate coolant loop, allowing for both forced and natural circulation, and incorporating an air heat exchanger to dump heat during low-power conditions, thereby reducing the reliance on safety-grade systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive heat removal system is used to remove decay heat during shutdown, then reactor safety is improved, but the system cannot effectively handle heat removal during startup procedures
Solution Approach 1:
The passive heat removal system is designed to perform multiple functions: it removes decay heat during shutdown through natural circulation and also handles heat removal during startup procedures. The system achieves this by incorporating components that enable both passive natural circulation mode and forced circulation mode, making it universally applicable to different operational phases of the reactor.
2Reliability
If safety-grade standards are applied to the heat removal system, then system reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The system incorporates passive safety features that enable it to automatically respond to thermal conditions without requiring complex active control systems. The natural circulation capability allows the system to self-regulate heat removal based on temperature differentials, reducing the need for complex instrumentation and control mechanisms while maintaining high reliability.
3Productivity
If natural circulation is promoted through gravity-driven flow, then heat removal efficiency during shutdown is improved, but flow control precision deteriorates
Solution Approach 1:
The system dynamically adapts its circulation mode based on operational requirements. During shutdown, it operates in passive natural circulation mode where gravity-driven flow provides sufficient heat removal efficiency. During startup, it transitions to forced circulation mode where pumps provide precise flow control. This dynamic switching capability allows the system to optimize for either heat removal efficiency or flow control precision depending on the operational phase.
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 enables efficient decay heat removal during shutdown and startup, promoting natural circulation and reducing thermal energy mixing, thus enhancing reactor safety and operational efficiency by utilizing gravity-driven fluid flow and asymmetric flow resistance to manage heat effectively.
Implementation Method 1
a fluidic diode disposed along the bypass flowpath between to asymmetrically restrict fluid flow along the bypass flowpath
Implementation Method 2
a pump in fluid communication with the intermediate coolant loop and configured to circulate intermediate coolant through the intermediate coolant loop
Implementation Method 3
an air heat exchanger disposed along a bypass flowpath between the hot leg and the cold leg of the intermediate coolant loop
Implementation Method 4
The natural circulation of fluid is promoted, by relying on gravity to cause the higher density cold fluid to fall and the lower density heated fluid to rise
Data Source
AI summary
A nuclear reactor is configured with an intermediate coolant loop for transferring thermal energy from the reactor core for a useful purpose. The intermediate coolant loop includes a bypass flowpath with an air heat exchanger for dumping reactor heat during startup and/or shutdown. A fluidic diode along the bypass flowpath asymmetrically restricts flow across the bypass flowpath, inhibiting flow in a first flow direction during a full power operating condition and allowing a relatively uninhibited flow in a second direction during a startup and/or shut down low power operating condition.