Induction Heating Stress Improvement Nozzle Cooling Verification
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Solution Overview
Problem
Conventional induction heating stress improvement methods for nuclear power plant primary loop recirculation piping face challenges in verifying cooling effects, especially in narrow annular clearances, due to difficulties in spraying fluids and removing stagnant air, which affects the efficiency and reliability of the cooling process.
Innovation Solution
The implementation of a thermometer to measure the temperature of the fluid flowing out from the annular clearance, combined with computational fluid dynamics analysis and specific nozzle tilting and placement strategies, ensures effective cooling by verifying the cooling effect and removing stagnant air through controlled evaporation and condensation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water flows are sprayed into the annular clearance to cool the piping inner surface, then the cooling effect is improved, but it is difficult to spray fluid into the narrow annular clearance and verify the cooling effect
Solution Approach 1:
The cooling apparatus is divided into multiple jet nozzles positioned at different locations around the annular clearance. Each nozzle targets a specific sector, allowing the complex cooling task to be broken into manageable segments that can be independently optimized and verified
Solution Approach 2:
Temperature sensors are installed within the annular clearance to provide real-time feedback on the cooling effect. This feedback mechanism allows verification of whether the jet flows are sufficiently cooling the inner surface, enabling adjustment of nozzle positions and flow rates to optimize performance
2Reliability
If multiple devices such as jet nozzles and piping are used to secure sufficient cooling effect, then the cooling reliability is improved, but the device complexity and number of redundant components increase
Solution Approach 1:
The cooling water piping system is designed to serve multiple functions: it provides cooling water to the jet nozzles, acts as a structural support framework, and incorporates temperature sensing capabilities. This multi-functionality reduces the need for separate dedicated components for each function
Solution Approach 2:
The temperature sensors are integrated directly into the cooling water piping structure rather than being separate independent devices. This merging of measurement and cooling functions reduces the total component count while maintaining reliable cooling performance
3Reliability
If air is removed from the closed stagnation portion such as the nozzle by water flows, then the IHSI execution is improved, but air stagnates in the nozzle and makes cooling impossible
Solution Approach 1:
Before initiating the induction heating stress improvement process, the system performs a preliminary air removal operation by circulating water flows through the nozzle and annular clearance. This preliminary action eliminates air pockets that would otherwise interfere with the subsequent cooling operation
Solution Approach 2:
The cooling water flow is maintained continuously through the nozzle and annular clearance throughout the IHSI process. This continuous flow prevents air from stagnating in the nozzle while simultaneously providing the necessary cooling effect on the piping inner surface
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 allows for reliable verification of the cooling effect and efficient relaxation of residual stress in the piping, reducing the need for redundant devices and ensuring safe operation by optimizing the flow and temperature distribution within the annular clearance.
Implementation Method 1
a thermometer is installed to a cooling apparatus for IHSI to measure the temperature of a fluid subjected to a temperature rise by cooling
Implementation Method 2
it is considered that a heated surface is being cooled due to a forced convection by the nozzle
Implementation Method 3
the relationship between the fluid temperature distribution in the annular clearance and the temperature of the fluid flowing out from the annular clearance is determined
Implementation Method 4
controlled evaporation and condensation processes
Implementation Method 5
Induction heating stress improvement
Data Source
AI summary
In implementing an induction heating stress improvement (IHSI) method in a nuclear plant, cooling characteristic with respect to the inner surface of piping is improved by appropriate structure/layout of nozzles, and further, the cooling effect when applying IHSI to a real machine is verified by installing a thermometer, as well as air in the portion subjected to IHSI is removed by heating the piping prior to the execution of IHSI.