R&D Forum

EPRI tracks eel movement through angled louver system

Owing to concerns about future American eel population size, resource agencies in the eastern U.S. and Canada are requesting protection of these fish. One aspect of this protection is ensuring safe downstream migration at hydro projects. A system of angled louvers and bar racks is one possible solution for guiding migrants to safe passage routes. To determine how such a system would affect eel movement, EPRI launched an American eel behavior and monitoring study.

The louver system used for the study was a 15-degree angled full-depth array at the 43.8-MW Holyoke project on the Connecticut River in Massachusetts. Tracking antenna were installed upstream, along, and downstream from the louver, as well as within the project’s fishway bypass facility. Researchers then tracked the movement behavior of 24 eels surgically implanted with radio tags and released upstream from the louver system. The fish were tracked until they exited the system via the bypass or through the louver, or until their tags failed.

In addition, researchers sought to determine if surgical implantation of radio tags influenced eel movement. For this aspect of the study, researchers also released 27 eels equipped with Floy tags, which do not require surgery. Researchers tracked their time of movement past the louver and into the bypass system.

During the study, many of the eels contacted the louver array multiple times. Upon encountering the system, the eels appeared to “search” for an exit route by moving downstream and upstream, as well as from the bottom to the surface of the water. This finding indicates that the louver acts more as a physical barrier to downstream migrants, rather than as a guidance device.

With regard to the effect of the tags, researchers determined that 42 percent of the eels with surgically implanted radio tags exhibited a period of delay in movement after release. Eels with Floy tags initially moved in substantially higher numbers (almost twice as many) over the same time period. This difference indicates that the stress associated with the surgical implantation likely contributed to the delay.

EPRI offers a report on this research, Movement Behavior of American Eel (Anguilla rostrata) on an Angled Louver Array at a Hydroelectric Project, EPRI Report 1012559.

EPRI hopes to conduct future studies to assess the guidance efficiency of a louver system. Future work depends on funding support and the ability to collect test specimens that have not previously had experience moving across a louver system.

– For information on availability of this report, contact (1) 800-313-3774; E-mail: askepri@epri.com. Or visit the Internet: www.epri.com and search for “angled louver.”

Project under way to identify crack characteristics of steel

Phase 2 has begun on a research project to characterize the fracture mechanics properties of stainless steel used to manufacture hydraulic turbine runners. This phase consists of characterizing steel samples supplied by well-known international foundries, then comparing the quality of these steels.

The purpose of the research project – initiated by Alstom, Hydro-Québec, and école polytechnique de Montréal – is to establish the crack propagation behavior of CA6NM-grade steels.

Data obtained from this research should provide valuable information for identifying the parameters that affect runner resistance for long-term operation. In addition, this information may be used to improve the quality of steel products and the reliability of hydraulic turbine runners.

Phase 1, completed by the end of 2006, focused on defining a sound and reliable protocol for the experimental procedure to be performed in the second phase. The goals of this phase were to develop a test procedure to provide reproducible base material fatigue curves and to discriminate crack geometry effects from microstructural effects.

Phase 2 work is divided into two parts.

First, researchers will compare the fatigue crack propagation (FCP) properties of the base materials. Reference curves in circulated water will be determined (following the protocol developed in Phase 1) in CA6NM steel from two suppliers whose materials currently are used for manufacturing hydraulic turbine runners. Fractographic analysis will be carried out on the fracture surfaces of the specimens to provide explanations of the difference between the FCP curves.

This study is to be completed by the end of 2007, and a report is to be issued at that time.

Second, researchers will evaluate the FCP properties of some weld metals (309L and 410Ni-Mo), including the effect of weld residual stresses. Another objective of researchers during this phase is to estimate the retardation effect of the base material FCP curves caused by overloads (e.g., during machine start up). Depending on the base materials, the FCP curves may be substantially affected by these overloads. In some cases (such as with austenitic stainless steels), drastic drops in the FCP rate are expected, which will be beneficial.

Two reports are to be issued on this study, the first by the end of 2007 and the second by the end of 2008.

Studying acoustic tag tracking of fish inside Wanapum Dam

Grant County Public Utility District (PUD) found through a recent study that acoustic tagging is an effective method for tracking juvenile salmonids within the intake of an operating turbine. Specifically, the study indicated that three-dimensional (3D) acoustic tag tracking could be used to determine the path of fish and where the fish encountered problems as they passed through the turbine intake.

This was the first time 3D fish tracking was accomplished within the confined space behind the trashracks at a hydroelectric facility, as the fish approached the turbine itself, says Sam Johnston, senior fisheries biologist with Hydroacoustic Technology Inc. (HTI). Grant County PUD hired HTI to perform this study.

For this study, performed at Grant County PUD’s 1,038-MW Wanapum Dam on the Columbia River in Washington, 32 juvenile steelhead were tagged with HTI tags for tracking and balloon tags for retrieval. The fish were released via a hose into the intake of Unit 5, behind the trashracks. The intake was equipped with five fixed hydrophones to detect the signals – two at the top of the intake, one in the middle, and two at the bottom.

The acoustic tags were programmed to transmit at a rate of 25 pings per second. This rate would provide a 3D position for at least every 1 foot of travel to just beyond the wicket gates.

Results were obtained for all 32 fish. Tracks indicated most fish followed the intake ceiling and moved downstream.

CEATI announces current research projects

The hydro interest groups of CEA Technologies Inc. (CEATI) announce current research activity. Projects are chosen based on issues raised by hydro utility representatives participating in the three interest groups: hydraulic plant life, dam safety, and water management.

The Hydraulic Plant Life Interest Group (HPLIG) consists of representatives from 40 organizations. Current projects of this group include:

– Dissolved oxygen monitoring. This project is identifying the best practices and best equipment technologies for monitoring dissolved oxygen levels in hydroelectric reservoirs, tailraces, and spillways; and

– Best practices in safety management and benchmarking. This project involves identifying the best practices in safety management and programming being used by hydro utilities and then benchmarking these programs.

The Dam Safety Interest Group (DSIG) consists of representatives from 25 dam owners. Research by this group includes:

– Dam monitoring and management. This research involves a review and comparison of current practices for data analysis and management; and

– Dam safety program effectiveness. This project reviews and compares current methods for measuring the effectiveness of a dam safety program, as well as identifying and further developing those methods that are most successful.

The Water Management Interest Group (WMIG) consists of representatives from 21 organizations. Current focuses in this area include:

– Accuracy of inflow forecasting. This project is assessing and reporting on the existing geographic and temporal accuracy of inflow forecasting tools; and

– Benchmarking hydroelectric water management. The focus is to analyze water resource management frameworks and jurisdictional approaches to identify key areas of commonality and conflict, as well as opportunities for improvement.

– For details on these projects or to join a CEATI hydro interest group, contact Chris Hayes at (1) 514-866-5370; E-mail: chris@ceatech.ca.

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