Turbine-Driven Pump Decay Heat Removal System
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Solution Overview
Problem
In nuclear reactors, passive cooling systems may fail to manage residual heat after a loss of heat sinking event, leading to rising coolant temperatures and pressures, potentially requiring emergency core cooling systems that involve depressurization, which can be risky.
Innovation Solution
A pressurized water reactor system incorporating a pressurizer and a turbine-driven pump connected by a common shaft, utilizing a pressurized passive condenser to drive water recirculation and control pressure, thereby avoiding ECCS activation and maintaining reactor safety without external power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive cooling systems are used to remove residual heat, then the system operates without external power, but the systems may fail to manage residual heat leading to rising temperatures and pressures
Solution Approach 1:
The turbine-driven pump uses the reactor's own steam pressure to drive the pump, creating a self-powered system that actively circulates coolant without external power. The steam from the pressurizer directly drives the turbine which drives the pump, forming a self-sufficient decay heat removal system.
Solution Approach 2:
The invention replaces passive thermal convection with an active mechanical circulation system. Instead of relying solely on natural convection and evaporation/condensation cycles, the turbine-driven pump mechanically forces coolant circulation through the reactor core, significantly enhancing heat removal capability.
2Reliability
If emergency core cooling systems are activated to depressurize the vessel, then coolant flow is maintained, but coolant loss and depressurization risks occur
Solution Approach 1:
The system converts the harmful high-pressure steam in the pressurizer into a beneficial driving force. The steam that would otherwise represent a pressure problem is instead used to drive the turbine and pump, creating useful mechanical work for active coolant circulation while simultaneously reducing pressurizer pressure.
Solution Approach 2:
The invention changes the operational parameters of the coolant system by maintaining higher pressure and temperature conditions. Instead of depressurizing the reactor vessel, the system operates at elevated pressures using the turbine-driven pump to force coolant circulation, thereby avoiding coolant loss while ensuring adequate flow.
3Temperature
If active cooling systems are used to aggressively control temperature and pressure, then temperature and pressure control is improved, but external power is required
Solution Approach 1:
The decay heat removal system is completely self-powered, using the reactor's own steam pressure to drive the turbine and pump. No external electrical power is required - the system harnesses the thermal energy already present in the pressurizer steam to create the mechanical work needed for active coolant circulation.
Solution Approach 2:
The system utilizes the phase transition of water to steam in the pressurizer as the energy source. The high-pressure steam generated during reactor operation is directed to the turbine, where it expands and drives the turbine blades, converting thermal energy into mechanical work to drive the pump.
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 solution provides aggressive yet safe temperature and pressure control within the reactor, preventing ECCS activation and ensuring long-term cooling without coolant loss, even in events like steam generator tube ruptures or feed water line breaks, by using the reactor's internal pressure to drive the decay heat removal system.
Implementation Method 1
steam from the pressurizer drives the turbine
Implementation Method 2
steam from the pressurizer drives the turbine which drives a pump
Implementation Method 3
steam exhausts into the pressurized passive condenser
Implementation Method 4
the pump is connected to suction water from the pressurized passive condenser into the reactor pressure vessel
Implementation Method 5
The pump and the turbine may be mounted on a common shaft so that the shaft provides direct mechanical coupling via which the turbine drives the pump
Data Source
AI summary
In conjunction with a pressurized water reactor (PWR) and a pressurizer configured to control pressure in the reactor pressure vessel, a decay heat removal system comprises a pressurized passive condenser, a turbine-driven pump connected to suction water from at least one water source into the reactor pressure vessel; and steam piping configured to deliver steam from the pressurizer to the turbine to operate the pump and to discharge the delivered steam into the pressurized passive condenser. The pump and turbine may be mounted on a common shaft via which the turbine drives the pump. The at least one water source may include a refueling water storage tank (RWST) and/or the pressurized passive condenser. A pressurizer power operated relief valve may control discharge of a portion of the delivered steam bypassing the turbine into the pressurized passive condenser to control pressure in the pressurizer.