In-Vessel Alkali Metal Reactor Natural Circulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current nuclear reactor designs face challenges in efficiently managing heat transfer and coolant purity, particularly in small, distributed reactors using liquid metals, which affect their operational reliability and longevity.
Innovation Solution
The implementation of an in-vessel natural circulation alkali metal reactor system with a coolant loop that utilizes alkali metals like sodium for heat transfer, incorporating a cold trap for coolant purification, booster pumps for startup assistance, and momentum-based circulators to facilitate natural circulation, along with modular components for easy maintenance and control systems for efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If natural circulation is used for coolant flow, then system complexity is reduced and reliability is improved, but heat transfer efficiency and flow control capability deteriorate
Solution Approach 1:
The system dynamically transitions between natural circulation mode (for normal operation) and forced circulation mode (for startup and high power conditions). Booster pumps are selectively activated to provide forced circulation when needed, while allowing natural circulation to dominate during steady-state operation, thus achieving both reliability and heat transfer efficiency.
Solution Approach 2:
Momentum-based circulators (flywheels) serve as intermediary devices that store rotational momentum and provide inertial drive to the coolant flow. These flywheels are driven by booster pumps during startup and then maintain circulation independently, bridging the transition from forced to natural circulation and ensuring continuous reliable operation.
2Ease of operation
If booster pumps and momentum-based circulators are added, then startup capability and flow establishment are improved, but device complexity increases
Solution Approach 1:
The momentum-based circulators (flywheels) are designed to maintain coolant flow independently after being initially driven by booster pumps. Once the flywheels are spinning at the required speed, they self-sustain the circulation through their stored rotational momentum, reducing the need for continuous active pump operation and simplifying control during steady-state operation.
Solution Approach 2:
The booster pumps operate periodically rather than continuously - they are activated during startup to bring the system to operating conditions, then deactivated during steady-state natural circulation, and only reactivated during transient conditions or power changes. This periodic operation reduces wear and simplifies the control system.
3Reliability
If cold trap purification system is implemented, then coolant purity is maintained, but heat loss and system complexity increase
Solution Approach 1:
The cold trap purification system is positioned at a specific location in the coolant loop where coolant temperature is already reduced (after passing through the reactor core and heat exchanger). By placing the cold trap in this cooler region rather than cooling the entire loop, the system achieves effective purification while minimizing the thermal energy required for operation and reducing overall heat loss.
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 design enhances heat transfer efficiency, maintains coolant purity, and ensures reliable operation from startup to full power, while allowing for easier maintenance and control of reactor power levels, thereby improving the overall performance and longevity of the reactor system.
Implementation Method 1
the liquid metal flows by natural circulation, transferring heat by natural convection
Implementation Method 2
transferring heat by natural convection
Implementation Method 3
a heat exchanger to transfer the heat from the coolant or cooling device to a power conversion system
Data Source
AI summary
Methods and systems for in-vessel natural circulation alkali metal reactor systems, purification systems, and associated methods are disclosed. A nuclear reactor vessel system includes an inner vessel that defines an inner volume sized to at least partially enclose a reactor. The reactor includes a plurality of nuclear fuel elements at least partially enclosed within a cladding, the reactor being cooled by a liquid metal coolant in a primary coolant loop. A pool of immersing fluid occupies a volume inside the inner vessel. The reactor vessel system includes an outer vessel sized to wholly or substantially enclose the inner vessel. A nuclear reactor power system includes a reactor core including an active fuel region; and a rotatable drum including at least one of a neutron absorbing material, a neutron leakage enhancing material, or a neutron reflecting material, the rotatable drum positioned external to the active fuel region of the reactor core.