Nuclear Reactor Startup System Using Preheating
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Solution Overview
Problem
The startup of natural circulation nuclear reactors can be unstable due to rapid temperature changes and power excursions when control rods are withdrawn, leading to complex and time-consuming processes to reach operating temperatures.
Innovation Solution
A stable startup system that introduces heat to the primary coolant before reactor core initialization, using a heating system located below the reactor core and a heat sink to create a buoyancy force for natural circulation, avoiding the need to withdraw control rods and minimizing power excursions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If control rods are withdrawn to achieve core criticality, then nuclear power generation is initiated, but rapid temperature changes and power excursions occur causing startup instability
Solution Approach 1:
The system performs preliminary heating of the coolant through electric heaters before initiating nuclear power generation. This pre-heating action stabilizes the thermal-hydraulic conditions and prevents rapid temperature changes and power excursions that would otherwise occur during startup, allowing for stable transition to criticality without abrupt transitions
Solution Approach 2:
Electric heaters are introduced as an intermediary device to mediate between the control rod withdrawal and the nuclear fission process. The heaters provide controlled thermal input that buffers the system against sudden power excursions, enabling stable startup by decoupling the direct relationship between control rod position and temperature changes
2Power
If control rods are withdrawn to initiate power generation, then heat is produced, but the process becomes complex and time-consuming to reach operating temperatures
Solution Approach 1:
The system performs preliminary heating of the coolant through electric heaters before initiating nuclear power generation. This pre-heating action stabilizes the thermal-hydraulic conditions and prevents rapid temperature changes and power excursions that would otherwise occur during startup, allowing for stable transition to criticality without abrupt transitions
Solution Approach 2:
The system changes the thermal parameters of the coolant by introducing controlled heating through electric heaters. This parameter change enables the coolant to reach stable operating temperatures more quickly and smoothly, reducing the time required to establish stable natural circulation conditions before nuclear power generation begins
3Manufacturing precision
If natural circulation is established through control rod withdrawal, then coolant flow is generated, but rapid temperature changes cause instability
Solution Approach 1:
Electric heaters are introduced as an intermediary device to mediate between the control rod withdrawal and the nuclear fission process. The heaters provide controlled thermal input that buffers the system against sudden power excursions, enabling stable startup by decoupling the direct relationship between control rod position and temperature changes
Solution Approach 2:
The system changes the thermal parameters of the coolant by introducing controlled heating through electric heaters. This parameter change enables the coolant to reach stable operating temperatures more quickly and smoothly, reducing the time required to establish stable natural circulation conditions before nuclear power generation begins
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 approach stabilizes the startup process, reduces the complexity and time required to reach operating temperatures, and prevents nuclear power excursions by establishing a controlled fluid flow through the reactor core, allowing for efficient and safe reactor operation.
Implementation Method 1
a heating system configured to introduce heat to the primary coolant prior to an initialization of the reactor core
Implementation Method 2
a heat sink configured to remove heat from the primary coolant after it has passed through the riser
Implementation Method 3
using a heating system located below the reactor core and a heat sink to create a buoyancy force for natural circulation
Implementation Method 4
When the water 10 is heated by the reactor core 6 as a result of fission events
Implementation Method 5
the water 10 that emerges from the riser 24 is cooled down and directed towards the annulus 23 and then returns to the bottom of the reactor vessel 2 through natural circulation
Data Source
AI summary
A stable startup system includes a reactor vessel containing coolant, a reactor core submerged in the coolant, and a heat exchanger configured to remove heat from the coolant. The stable startup system further includes one or more heaters configured to add heat to the coolant during a startup operation and prior to the reactor core going critical.