US-20260125869-A1 - Auxiliary Facilities and Method for Fish Resource Recovery in Open Water Diversion Channel

US20260125869A1US 20260125869 A1US20260125869 A1US 20260125869A1US-20260125869-A1

Abstract

The present invention relates to an auxiliary method and facility for fish resource recovery in an open water diversion channel, which includes: an inlet of the attraction channel arranged on a side wall of the open water diversion channel, a slope provided inside the attraction channel, wherein a lower end of the slope is located inside the open water diversion channel, and a higher end of the slope is located outside the open water diversion channel, an attracted water flow is arranged at the higher end of the slope to guide fish into the attraction channel and an outlet of the attraction channel is connected to a still water zone, wherein the still water zone is provided with a release device. The present invention effectively guides a significant number of fish that have mistakenly entered the open water diversion channel out of the channel through attracted attraction. This approach not only protects fish resources but also prevents channel blockages caused by massive fish intake, thereby avoiding power plant shutdown incidents, thus preventing substantial economic losses and, more importantly, ensures the operational safety of the power plant.

Inventors

Rui Han
Li Zeng
Qiang Zhang
Ranran Cao
Jia Yang
Wei Bai
Yijun Zhao
Ping Ji

Assignees

CHINA INSTITUTE OF WATER RESOURCES AND HYDROPOWER RESEARCH

Dates

Publication Date: 20260507
Application Date: 20250710
Priority Date: 20241107

Claims (7)

1 . An auxiliary method for fish resource recovery in an open water diversion channel, wherein an auxiliary facility for fish resource recovery in the open water diversion channel is used for the auxiliary method, the auxiliary facility comprising: an inlet of the attraction channel arranged on a side wall of the open water diversion channel, a slope provided inside the attraction channel, wherein a lower end of the slope is located inside the open water diversion channel, and a higher end of the slope is located outside the open water diversion channel, an attracted water flow is arranged at the higher end of the slope to guide fish into the attraction channel and an outlet of the attraction channel is connected to a still water zone, wherein the still water zone is provided with a release device, an interception net arranged downstream of the inlet of the attraction channel; and the auxiliary method comprises the following steps: step 1: establishing a water intake zone three-dimensional flow field model: establishing the water intake zone three-dimensional flow field model which includes the open water diversion channel, acquiring topography of the water intake zone, ambient flow conditions, shoreline characteristics, as well as the design dimensions, water intake flow rate, intake flow velocity, and intake depth of the open water diversion channel, establishing a water intake flow field model, dividing computational grids, determining boundary conditions and initial conditions for flow field simulation, and selecting appropriate computational parameters to simulate flow field variations including the open water diversion channel and its affected water area; wherein the governing equations for flow field computation are as follows: ∇ · u = 0 ∂ u ∂ t + u · ∇ u = - ∇ p ρ + 1 ρ ⁢ ∇ · ( μ eff ⁢ ∇ u ) - 2 3 ⁢ ∇ · ( kI ) ∂ ∂ t ( ρ ⁢ k ) + ∇ · ( ρ ⁢ ku ) = ∇ · ( α k ⁢ μ eff ⁢ ∇ k ) + G k - ρε ∂ ∂ t ( ρε ) + ∇ · ( ρε ⁢ u ) = ∇ · ( α ε ⁢ μ eff ⁢ ∇ ε ) + C 1 ⁢ ε ⁢ ε k ⁢ G k - ρ ⁢ C 2 ⁢ ε ⁢ ε 2 k wherein u is a time-averaged velocity, t is time, p is pressure, ρ is water density, μ eff is a turbulent effective viscosity, k is turbulent kinetic energy, I is second-order unit tensor, α k is a turbulent kinetic energy Prandtl number, ε ε is a turbulent dissipation rate, α ε is a turbulent dissipation rate Prandtl number, G k is a turbulent kinetic energy generation term caused by an average velocity gradient, and C 1ε and C 2ε are constant coefficients; step 2: validating the flow field model based on physical model experiments: constructing a corresponding geometrically scaled physical model indoors, and measuring the flow velocity and direction at characteristic cross-sections or points within the attraction channel, comparing these measurements with simulation results of the mathematical model for validation, wherein if the calculated values align well with the measured values, the established mathematical model can reflect basic characteristics of flow field distribution in the open water diversion channel, based on this, the location where fish resource recovery facilities are located in the open water diversion channel, as well as the water flow rate and configuration dimensions of the attracted water flow can be determined; step 3: selecting the location of the attraction channel: based on flow field distribution analysis and considering swimming capabilities and behavioral characteristics of fish entering the channel, locating the inlet of the attraction channel near a bank in a low-velocity area at the center of a recirculation zone where recirculation is relatively weak, wherein the outlet of the attraction channel is placed in a near-bank area outside the channel where the water flow is slow and stable, serving as a temporary holding area for fish before release; step 4: determining configuration, dimensions, and attracted water flow rate of the attraction channel: based on flow field distribution analysis, combined with the swimming capabilities and behavioral characteristics of fish entering the channel, as well as the flow velocity and flow patterns within the attraction channel, comprehensively determining the configuration, dimensions, and the attracted water flow rate of the attraction channel; step 5: modifying a physical model experiment for further flow field verification: according to the recommended attraction channel design proposed in step 4, modifying the physical model in step 2 by adding the attraction channel and a water supply system at the corresponding location in the channel, then conducting the physical model experiment to further study and analyze the flow field, and verifying suitability of the fish resource recovery facilities; step 6: providing auxiliary interception facilities: based on flow field analysis results in the channel, installing an auxiliary interception net downstream of the inlet of the attraction channel in an area with relatively uniform and low-velocity flow, wherein the interception net spans the entire cross-section, encouraging fish to more easily find the inlet of the attraction channel while swimming along the net; and step 7: fish attraction and recovery process: activating the attraction channel, creating a jet flow from the recirculation zone to a main flow zone at the inlet of the attraction channel; utilizing fish's innate tendency to swim against currents and support of auxiliary facilities, guiding the fish in both the main flow and recirculation zones toward the inlet of the attraction channel, wherein the slope within the attraction channel generates a stable, uniformly graded reverse flow field, attracting fish to swim upstream to the still water zone at the outlet of the attraction channel, then the fish in the still water zone are released into natural waters outside the channel via the release device.
2 . The auxiliary method according to claim 1 , wherein the direction of the attracted water flow forms an angle of 90 degrees or greater with the flow direction in the open water diversion channel.
3 . The auxiliary method according to claim 2 , wherein the open water diversion channel comprises two parallel side walls forming a straight channel section, a 90-degree elbow is provided at the end of the straight channel section, making the open water diversion channel inlet parallel to one side wall, the inlet of the attraction channel is arranged on the side of the recirculation zone in the open water diversion channel at a position 2-3 inlet widths away from the open water diversion channel inlet, and the attracted water flow perpendicular to the open water diversion channel can penetrate through the recirculation zone in the open water diversion channel.
4 . The auxiliary method according to claim 3 , wherein the slope gradient of the attraction channel is less than 1:10, the width should not exceed 5 m, and the water depth should not be less than 0.5 m.
5 . The auxiliary method according to claim 4 , wherein an attracted water flow rate is 1/15 of the water flow rate in the open water diversion channel.
6 . The auxiliary method according to claim 5 , wherein the release device is a fish guidance channel.
7 . The auxiliary method according to claim 5 , wherein the release device is a fishing trap.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims the priority benefit to Chinese application No. 202411583273.3 filed on Nov. 7, 2024, the entirety of which is hereby incorporated by reference and made a part of this specification. TECHNICAL FIELD The present invention relates to an auxiliary facility and method for fish resource recovery in an open water diversion channel, which pertains to hydraulic engineering and methods for protecting fish ecology during power plant water intake processes. It serves as a measure to reduce the impact of open channel water intake on fish resources and mitigate risks associated with water intake entrainment, impingement, and nuclear power cold source hazards, thereby enhancing the operational safety and environmental friendliness of water intake projects. This invention provides an environmentally friendly auxiliary facility and method for fish resource recovery in open water diversion channels that considers fish behavioral characteristics and water intake flow field distribution patterns. BACKGROUND ART In recent years, multiple incidents of nuclear power plant water intake blockages have occurred, caused by organisms including commercial fish species, jellyfish, and algae. These incidents have forced nuclear power plants to shut down reactors, cease operations, or reduce power output, resulting in significant economic losses and, more importantly, posing serious threats to nuclear power operational safety. Meanwhile, against the backdrop of vigorous ecological civilization development, the ecological impact of nuclear operation has become a key focus in industry development. The adverse effects of nuclear power water intake on marine organisms, particularly fish resources, have hindered the harmonious development between nuclear power and marine environments. Research on the impact of the nuclear power water intake on fish began in the 1970s. Studies indicate that fish entering nuclear power water intake systems exhibit low survival rates and high mortality, directly causing fish resource losses from nuclear power water intake. For instance, the Bay Shore Nuclear Power Plant in the United States, with a total operational capacity of 631 MW and water intake of 33 m3/s, the results from monitoring show the plant entrains approximately 4.6×107 adult fish annually, predominantly Anomalopidaes and gizzard shads. Current mitigation measures primarily include reducing intake flow velocity, decreasing water intake volume, and installing barrier nets around intake structures. However, no corresponding facilities have been implemented within open water diversion channels to recover fish resources that enter the open water diversion channel and minimize water intake impacts on the fish. While ensuring cold source safety, nuclear power plants must protect marine organisms during water intake processes and reduce biologically attracted losses. At present, most existing nuclear power plants neglect water intake impacts of the water intake facilities on fish. Some plants have gradually begun recording entrained fish biomass data, but none have constructed fish resource recovery facilities. There is an urgent need to incorporate fish resource recovery facilities in water intake systems. How to recover and protect fish entering the open water diversion channels, reduce intake impingement, and prevent intake blockages remains a critical problem to be solved. SUMMARY OF THE INVENTION In order to overcome the problems of the prior art, the present invention provides an auxiliary facility and method for fish resource recovery in an open water diversion channel. The facility and method involve providing an attraction channel and attracting water flow on one side of the open water diversion channel inlet to attract fish that have mistakenly entered the open water diversion channel into a specially designed attraction channel, then guide them through the channel to a still water zone outside the open water diversion channel. Subsequently, the fish in the still water zone are either guided or captured and are released into natural waters. An objective of the present invention is achieved as follows: an auxiliary facility for fish resource recovery in an open water diversion channel, which includes: an inlet of the attraction channel arranged on a side wall of the open water diversion channel, a slope provided inside the attraction channel, wherein a lower end of the slope is located inside the open water diversion channel, and a higher end of the slope is located outside the open water diversion channel, an attracted water flow is arranged at the higher end of the slope to guide fish into the attraction channel and an outlet of the attraction channel is connected to a still water zone, wherein the still water zone is provided with a release device, an interception net arranged downstream of the inlet of the attraction channel. Further, the direction of the attracted water flow fo