Dryout Estimation Formula for Boiling Water Reactors
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Solution Overview
Problem
Current methods for estimating dryout in nuclear light water reactors, particularly boiling water reactors, are complex and require numerous coefficients, making it difficult to accurately predict dryout properties and maintain a safe margin, especially during transient conditions and when extrapolating from limited experimental data.
Innovation Solution
A simplified formula that expresses local dryout properties in terms of flow, axial power profile, R-factor, and pressure dependencies, using fewer significant fitting coefficients and accounting for transient phenomena, allowing for accurate estimation of dryout conditions and margin without extensive experimental data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current methods for estimating dryout are used, then dryout properties can be predicted, but the methods are complex and require numerous coefficients
Solution Approach 1:
The patent segments the complex dryout prediction into distinct functional components: a flow-dependent term, an axial power profile term, and an R-factor term. Each component addresses a specific physical phenomenon independently, allowing the overall prediction to be built from manageable segments rather than a monolithic complex model.
Solution Approach 2:
The patent extracts and isolates the most significant parameters that influence dryout (flow, axial power profile, and R-factor) from the complex set of numerous coefficients in traditional methods. By focusing only on these key extracted parameters, the method achieves accurate prediction without requiring all the coefficients of conventional approaches.
2Reliability
If traditional correlation methods are used, then dryout data can be correlated, but numerous coefficients are required making it difficult to maintain safe margin
Solution Approach 1:
The patent changes the parameters used in dryout correlation from numerous traditional coefficients to three physically meaningful terms: flow-dependent term, axial power profile term, and R-factor term. This parameter transformation maintains reliability by preserving the essential physics while reducing complexity to a manageable set of parameters that are easier to control and validate.
3Measurement precision
If experimental data is used for estimation, then dryout properties can be predicted, but extensive experimental data is required
Solution Approach 1:
The patent performs preliminary action by establishing a physically-based correlation structure that incorporates the essential physics of dryout (flow, power profile, and R-factor effects) before actual operation. This pre-established framework allows accurate prediction with minimal experimental data, as the physical principles are already encoded in the correlation rather than requiring extensive data collection to derive them.
4Measurement precision
If complex methods are used to account for transient conditions, then accurate prediction during transients is possible, but the methods become even more complex
Solution Approach 1:
The patent applies dynamics by making the correlation adaptable to changing conditions through the R-factor term, which captures the influence of neighboring rods and local power distribution variations. This dynamic component allows the model to respond to transient conditions and spatial variations without requiring a completely different complex model for each scenario.
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 formula provides a straightforward method to estimate dryout properties and margin, improving accuracy and reducing the need for numerous coefficients, enabling better control and operation of nuclear reactors by accounting for transient effects and varying conditions.
Implementation Method 1
A mixture of steam and water is flowing through the fuel bundle, providing cooling for the rods by convective and boiling heat transfer
Implementation Method 2
A mixture of steam and water is flowing through the fuel bundle, providing cooling for the rods by convective and boiling heat transfer
Implementation Method 3
The existence of this film allows for efficient heat transfer from the rods to the coolant
Implementation Method 4
The existence of this film allows for efficient heat transfer from the rods to the coolant. This enables both effective steam generation and prevents the rods from overheating
Data Source
Figure 1
AI summary
The invention concerns a method of estimating when dryout may occur in a nuclear light water reactor of the boiling water reactor kind. The method includes the use of a formula which expresses the local dryout property of the nuclear reactor. The formula includes at least a first and a second factor. The first factor is a first function that describes how the dryout property depends on the flow of the cooling medium through the nuclear fuel arrangement. The second factor is a second function that describes how the dryout property depends on the axial power profile of the nuclear fuel arrangement. The first and the second functions describe said flow dependence and said axial power profile dependence independently of each other. The invention also concerns a nuclear energy plant, a computer program product (23) and a method of operating a nuclear energy plant.