1

Use of an autonomous sensor to evaluate the biological

performance of the advanced turbine at Wanapum Dam

Zhiqun Deng,a) Thomas J. Carlson, Joanne P. Duncan, Marshall C. Richmond, Dennis D.

Dauble

Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352,

USA

Abstract

Hydropower is the largest renewable energy resource in the United States and the

world. However, hydropower dams have adverse ecological impacts because migrating

fish may be injured or killed when they pass through hydro turbines. In the Columbia

and Snake River basins, dam operators and engineers are required to make those

hydroelectric facilities more fish-friendly through changes in hydro-turbine design and

operation after fish population declines and the subsequent listing of several species of

Pacific salmon under the Endangered Species Act of 1973. Public Utility District No. 2

of Grant County, Washington, requested authorization from the Federal Energy

Regulatory Commission to replace the 10 turbines at Wanapum Dam with advanced

hydropower turbines designed to improve survival for fish passing through the turbines

while improving operation efficiency and increasing power generation. As an additional

measure to the primary metric of direct injury and mortality rates of juvenile Chinook

salmon using balloon tag-recapture methodology, this study used an autonomous sensor

device—the Sensor Fish—to provide insight into the specific hydraulic conditions and

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physical stresses experienced by the fish, as well as the specific causes of fish biological

response. We found that the new hydro-turbine blade shape and the corresponding

reduction of turbulence in the advanced hydropower turbine were effective in meeting the

objectives of improving fish survival while enhancing operational efficiency of the dam.

The frequency of severe events based on Sensor Fish pressure and acceleration

measurements showed trends similar to those of fish survival determined by balloon tag-

recapture methodology. In addition, the new turbine provided a better pressure and rate

of change environment for fish passage. Overall, the Sensor Fish data indicated that the

advanced hydro-turbine design improved passage of juvenile salmon at Wanapum Dam.

Keywords: hydropower, dams, advanced turbine, fish passage, sensor fish device

a) Author to whom correspondence should be addressed. Electronic mail: zhiqun.deng@pnl.gov. Tel: +1-

509-372-6120. FAX: +1-509-372-6089

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I. INTRODUCTION

Hydropower is the world’s largest renewable energy resource, accounting for more

than 75% of the global total renewable electric power capacity.1 In the United States,

hydropower provides about 70% of the total renewable electric generation and 6% of the

total electricity, with the Columbia and Snake River basins contributing to 50% of the

nation’s total hydroelectric energy.2 However, hydropower dams may injure or kill fish

that live in or migrate through impounded river systems.3-5 Several species of

anadromous Pacific salmon in the Columbia and Snake River basins are currently listed

for protection under the Endangered Species Act of 1973. Consequently, dam operators

and engineers are required to make these hydroelectric facilities more fish-friendly

through changes in hydro-turbine design and operation.6,7

In 2003, the Public Utility District No. 2 of Grant County, Washington (Grant PUD)

requested authorization from the Federal Energy Regulatory Commission (FERC) to

replace the 10 turbines at Wanapum Dam on the Columbia River in Washington State.8

The existing Kaplan-type turbines have been in place for more than 40 years and were

reaching the end of their useful machine life. Grant PUD proposed to replace the turbines

with an advanced hydropower turbine (AHT) design that would include features to

improve survival for fish passing through the turbines while improving operation

efficiency and increasing power generation from 895 megawatts (MW) to 1,118 MW.

Major changes in the AHT design to reduce adverse impacts to fish during turbine

passage and improve hydraulic conditions included reshaped stay vanes, improved

alignment and reduced size of wicket gates, a runner with six blades (the existing one has

five blades), a discharge ring to eliminate gaps at the hub and discharge ring, and

4

reshaped draft tube to reduce turbulence. Major features of the AHT design for

improving operation efficiency and increasing power generation included a larger turbine

runner diameter, greater hydraulic capacity, and increased number of wicket gates (Fig.

3). One of these AHTs was installed at Wanapum Dam turbine Unit 8 for testing in

2005.

The first step in biological performance testing for the new AHT was to compare fish

passage and survival estimates and hydraulic conditions between the AHT and existing

conventional turbine designs. Based on this information, a decision would be made on

whether to proceed with replacement of the remaining nine turbines with the new AHTs.

The U.S. Department of Energy Office of Energy Efficiency and Renewable Energy

provided co-funding to Grant PUD for aspects of performance testing that supported the

FERC application. The primary measure of biological performance for the application

was direct injury and mortality rates of juvenile Chinook salmon as determined by

balloon tag-recapture methodology.9,10 A randomized block experiment was conducted

that included the two turbine types (conventional and AHT), three intake bays, two

entrainment locations within each turbine, and four discharge levels.11 Although balloon

tag-recapture field studies are used routinely to evaluate turbine biological performance,

they do not provide insight into the specific hydraulic conditions or physical stresses that

the fish experience or the specific causes of the biological response. To overcome this

limitation, an autonomous sensor device developed by Pacific Northwest National

Laboratory was released concurrently with balloon-tagged live fish to measure hydraulic

conditions such as pressure, acceleration, and rotation acting on the sensor’s body in situ

during downstream passage.12,13 The specific objectives of this study were 1) to develop

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and apply a methodology to classify Sensor Fish acceleration events and to analyze those

events for general regions within the turbine system; 2) to statistically analyze Sensor

Fish data together with live fish biological response data; and 3) to use Sensor Fish data

to assess whether the AHT design features led to improved biological performance.

II. METHODS

A. Test site

Wanapum Dam is within the Priest Rapids Project and is located in central

Washington State on the Columbia River at river kilometer (rkm) 668 (Fig. 1). It consists

of a 305-m 10-turbine powerhouse, a 250-m 12-bay spillway, and a non-overflow earth-

fill section. Columbia River average discharge at this location is approximately 3,400

m3/s.

B. Sensor Fish device

The Sensor Fish (Fig. 2) is an autonomous device developed at Pacific Northwest

National Laboratory for the U.S. Department of Energy and the U.S. Army Corps of

Engineers to better understand the physical conditions fish experience during passage

through hydro turbines, spillways, and other dam bypass alternatives. It measures the

three-dimensional linear acceleration and three-dimensional angular velocities, plus

pressure and temperature, at a sampling frequency of 2,000 Hz. The Sensor Fish device

is 24.5 mm in diameter and 90 mm in length, weighs 42 g (comparable to a yearling

salmon smolt), and is nearly neutrally buoyant in fresh water. Sensor Fish devices

deployed for such studies are tested in a calibration apparatus prior to deployment. The

relative errors of both the linear acceleration and angular velocity measurements are

consistently less than 5%.13 The Sensor Fish has been used extensively in both

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laboratory environments14 and hydroelectric dam field environments15 to correlate with

fish injury and provide information on severe hydraulic conditions.

C. Study design

The existing turbine at Wanapum Dam Unit 9 was selected as the conventional

turbine to compare with the new AHT at Unit 8. Passage conditions (treatments)

consisted of combinations of factors including turbine discharge, the intake bay, and

release depth (entrainment depth). In both turbines, Sensor Fish were injected at the

centerline of each of three intake bays and at two elevations (152 m and 146 m, termed

shallow and deep releases, respectively) at the same horizontal locations (Fig. 3). The

two release pipe elevations were 3 m and 9 m lower than the turbine ceiling elevation

(155 m). Consideration of elevation prior to turbine runner passage is critical because

previous turbine biological assessments have found the elevation of entry influences the

turbine passage route. For Kaplan turbines, fish passing lower through the wicket gates

will pass nearer the runner blade tips while those passing higher through the wicket gates

will pass nearer to the runner hub assuming fish follow the flow streamlines. Mortality

rates for fish are significantly higher for fish that pass near the blade tips than for those

that pass mid-blade and near the runner hub.16 All sensor fish releases were interspersed

with the balloon-tagged fish being evaluated in a separate study conducted by

Normandeau Associates, Inc.17 Four discharge conditions (255, 311, 425, and 481 m3/s)

were evaluated for each turbine, in addition to a maximum discharge condition of 524

m3/s for the AHT. A total of 891 Sensor Fish were released.

D. Data analysis

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Pressure measurements were used to estimate the depth and location of the Sensor

Fish device. For both the conventional turbine and AHT, general distinctive features

were associated with passage locations, including the time of passage from the injection

pipe exit into the turbine intake, through the stay vane-wicket gate cascade, through the

runner and runner wake, and through the draft tube (Fig. 4).

When Sensor Fish contact solid structures or are impacted by turbulent shear, high-

amplitude impulses occur in the acceleration and rotational velocity time history. If the

acceleration reaches a certain threshold, the exposure is counted as an exposure event.

Based on previous laboratory studies18, the event is further categorized into three levels

according to the acceleration magnitude (|a|): 1) severe if ga 95≥ ; 2) medium if

gag 5095 ≥> ; and 3) slight if gag 2550 ≥> . The identification of an event as

collision or shear is based on the characteristics of acceleration during the exposure

event. Peak duration was defined as the duration of acceleration within 70% of the peak

value and used as the criterion to distinguish collision from shear: the exposure event is a

collision event when peak duration is less than 0.0075 second, and the event is a shear

event when peak duration is longer than 0.0075 second.13 Standard deviations of the

probabilities of collisions or shear events were derived using the bootstrapping method.19

In addition to injury from collisions and shear, fish may be injured or killed by

exposure to rapid changes in pressure during turbine passage. The magnitude and rate of

change in pressure are greatest during passage from the wicket gates to exit of the runner.

The lowest pressures (nadir pressure) are observed on the underside, or “suction” side, of

turbine blades, while the highest are observed on the upper surface of the blades.

Changes in the operating geometry of a turbine as well as the design of runner blades and

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other turbine elements also affect the magnitude and distribution of pressure in a turbine.

To account for the complexity of the pressure environment, we computed the range and

median of nadir total pressure for each treatment and rate of pressure calculations. The

magnitude of pressure change was computed from the pressure measurements obtained

by sensors as they were carried in flow from the wicket gates through the nadir around

the turbine runner. Pressure rate of change was then estimated by dividing the pressure

change measurement by the corresponding travel time.

III. Results and discussion

A. Exposure events

Severe exposure events were primarily collisions. Of the 891 total releases, there

were 185 severe collision events compared to 18 severe shear events. When all

discharges and release elevations are combined, the number of severe events in the stay-

vane/wicket-gate and draft tube regions was effectively the same for both turbines (Fig.

5). The new AHT at Unit 8 had a lower probability of severe events in the runner region

compared to those at the conventional turbine at Unit 9. However, due to small sample

size, there were no clear trends when the data were examined by discharge and release

elevation.

In the intake region for both turbines, there were only very few slight events (6

collisions and 1 shear); there were no severe or medium events. In the stay-vane/wicket-

gate region, the AHT had a slightly higher probability of severe collision (13.6% ± 1.5%)

than the conventional turbine (10.7% ± 1.7%). Both turbines had very few severe shear

events (0.4% and 0.8%, respectively), but the AHT had more slight shear events (14.2%

± 1.5%) than the conventional turbine (6.2% ± 1.3%). In the runner region, the

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conventional turbine had more severe collision events (9.6% ± 1.6%) and more severe

shear events (3.9% ± 1.0%) than the AHT (4.9% ± 0.9% for severe collision and 0.7% ±

1.1% for shear). In the draft tube region, there were very few slight shear events (a total

of four) and no severe or medium shear events for both units. In addition, the percentage

of severe collisions was almost identical for the AHT (3.4% ± 0.8%) and the

conventional turbine (3.4% ± 1.0%) in this region.

When all four regions were pooled together (Fig. 6), the two turbines had almost

identical probability of severe collisions at 20.5% ± 1.8% and 21.1% ± 2.2% even though

the AHT had a 6-blade runner while the conventional turbine had a 5-blade runner. In

addition, the probabilities for both medium and slight collisions were similar for both

turbines. The AHT had fewer severe shear events (1.1% ± 0.5%) than the conventional

turbine (3.4% ± 1.2%), but the AHT had more slight shear events (29.3% ± 2.0%) than

the conventional turbine (19.7% ± 2.5%), possibly due to the addition of more wicket

gates to the AHT (i.e., 32 compared to 20 for the conventional turbine).

There was no statistical evidence to suggest a significant difference of severe or

medium events for these two turbines with all shear and collision combined. However,

the AHT produced a slightly lower probability of severe events (21.3% ± 1.8%) than Unit

9 (23.7 ± 2.2%). For both turbines, the Sensor Fish device released from the deep

location (146-m elevation) experienced a significantly higher probability of a severe or

medium event than those from shallow releases (Fig. 7). This finding is consistent with

the results of the live fish study showing that fish from deep releases had significantly

lower survival rates that those from shallow releases.17

B. Pressure

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Recent research using simulated turbine passage pressure exposure indicates that

factors such as nadir pressure, the depth acclimation history of fish and their state of

buoyancy prior to turbine entry, significantly affect rates of injury and mortality.20

Median nadir total pressure and range measured by the sensor fish device decreased with

discharge for both turbine units (Fig. 8). The new AHT showed higher nadir values and a

narrower range than the conventional turbine. The difference in median nadir pressure

was consistent at approximately 23 kPa for all discharges. However, the lowest nadir

pressures observed for the new turbine were approximately 70 kPa higher than those for

the existing design turbine at the highest discharges tested.

The magnitude of pressure change from the turbine wicket gate through the runner

exit was found to be consistently higher across discharge for both turbines for deep

releases (Fig. 9). The new AHT had a smaller pressure change than the conventional

turbine at the same release depth. However, the mean values for the shallow releases for

the conventional turbine were lower or similar to those for the AHT deep releases. The

highest rates of change were observed for the deep releases for the conventional turbine.

The lowest pressure changes were observed for the shallow releases for the AHT.

The average pressure rate of change steadily increased with discharge for both test

turbines (Fig. 10). Trends similar to those observed for the magnitude of change in

pressure were evident in the rate of change observations as well. The highest average

rates of change were observed for the deep releases in the conventional turbine unit. The

lowest rates of change were observed for the shallow releases in the new AHT.

C. Comparison of Sensor Fish device data with live fish data

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There were fewer severe events for shallow versus deep releases, which was

reflected in fish survival rates (Table I). The overall rates of severe events for each

turbine were similar, although the AHT had slightly fewer events than the conventional

turbine. This trend was not reflected in the live fish survival rate, where the AHT had a

slightly lower survival rate than the conventional turbine. 17 However, the differences

were not significant. The survival rates were only the direct effects of turbine passage

from the turbine system. Fish were recovered immediately after they passed through the

dam and held for 48 hours. Fish injuries due to predation were excluded when estimating

the injury rates due to the turbine environment. Indirect mortality that may occur at a later

time as a result of passage through the hydro-system was not considered either. Overall,

the results could not reject the primary hypothesis that fish survival rate through the new

AHT is equal or better than that through the original turbine.

III. Conclusion

Although the AHT at Unit 8 had a six-blade runner, it showed a reduced rate of severe

collisions (4.9% ± 0.9%) compared to the five-blade runner of the conventional turbine at

Unit 9 (9.6% ± 1.6%). Severe shear events were also fewer in the AHT. These results

suggested that the new blade shape and the corresponding reduction turbulence in the

AHT were effective in meeting the objectives of improving fish survival while enhancing

operational efficiency and increasing power generation. The draft tube in the AHT was

also modified to improve hydraulic conditions. However, Sensor Fish results did not

show a significant difference in severe events between the two turbines that corresponded

to passage through this region. The frequency of severe events, based on Sensor Fish

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pressure and acceleration measurements, showed similar trends to fish survival

determined by balloon-tag tests. This trend was consistent within each turbine unit and

by entrainment depth. In addition, the new AHT turbine provided better pressure and rate

of change environment for fish passage. Overall, the Sensor Fish data indicated that the

AHT design improved the passage of juvenile salmon at Wanapum Dam. The Federal

Energy Regulatory Commission approved the relicensing application of Wanapum Dam

by Grant PUD, and the remaining nine turbine units are being replaced with the AHT

turbines and will be completed by 2012.

Acknowledgments

This project was funded by Grant PUD and the U.S. Department of Energy (DOE)

Office of Energy Efficiency and Renewable Energy Wind and Hydropower Technologies

Program. Curt Dotson was the contracting officer for Grant PUD, and Jim Ahlgrimm

was the contracting officer for DOE. We also wish to thank Grant PUD, Normandeau

Associates, Inc., and numerous PNNL staff. The Pacific Northwest National Laboratory

(PNNL) is owned by DOE and operated by Battelle Memorial Institute under Contract

DE-AC05-76RL01830.

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13

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Wanapum Dam, Columbia River, Washington, prepared for Public Utility District No. 2

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Dauble, Response relationship between juvenile salmon and an autonomous sensor in

turbulent flows, Fisheries Research 97(1-2):134-139. DOI:10.1016/j.fishres.2009.01.011

(2009).

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Pennsylania (2005).

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Tables

TABLE I. Comparison of Sensor Fish severe event (collision and shear) and live fish

survival rates for each turbine. Live fish data are from Normandeau et al.17 Standard

error is in parentheses.

TurbineEntraiment

depthSensor Fish

device samplesSevere Event

(+/- SE)Live fish samples

Live Fish 48-h Survival(+/- SE)

Shallow 223 14.3% (2.3%) 1833 98.5% (0.6%)AHT Deep 313 26.2% (2.5%) 1834 95.5% (0.6%)

Pooled 536 21.3% (1.8%) 3667 97.0% (0.7%)Shallow 181 16.6% (2.8%) 1829 97.9% (0.6%)

Conventional Deep 174 31.0% (3.5%) 1829 97.1% (0.7%)Pooled 355 23.7% (2.2%) 3658 97.5% (0.5%)

17

Figures

FIG. 1. Location of Wanapum Dam on the Columbia River in central Washington State.

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FIG 2. Sensor Fish device. Drawing shows the measurement axes for the three

components of linear acceleration (up-down, forward-back, and side-to-side)

and three components of angular velocities (pitch, roll, and yaw).

19

FIG. 3. Side and top views of turbine intake, scrollcase, draft tube, and location of live

fish and Sensor Fish release pipes.

20

Time (second)

Abs

olut

epr

essu

re(k

Pa)

34 35 36 37 380

100

200

300

400

Stay vane -wicket gatecascade

Runner passage

In draft tube

Collision withstay vane

Time (second)

Rot

atio

nalv

eloc

ity(d

eg/s

)

34 35 36 37 38 0

500

1000

1500

2000

2500

Time (second)

Acc

eler

atio

n(g

)

34 35 36 37 38 0

50

100

150

200

250

FIG 4. An example of turbine passage measurements using the Sensor Fish device at

Wanapum Dam.

21

FIG 5. Comparison of probabilities of severe collision or shear events in different

regions of the turbine with all discharges and release elevations combined.

22

FIG 6. Comparison of probabilities of collision and shear events for the two turbines,

with all regions, discharges, and release elevations combined.

23

FIG 7. Comparison of probabilities of exposure events by different release pipe

elevations, with all regions and discharges combined.

24

0

40

80

120

160

200

200 250 300 350 400 450 500 550

Med

ian

tota

l pre

ssur

e at

nad

ir an

d ra

nge

(kPa

)

Unit discharge (m3/s)

AHTConventional

FIG 8. Median and range of lowest pressure (nadir) recorded by Sensor Fish.

25

FIG. 9. Average magnitude of change in pressure during transit of the sensor from

wicket gate passage to exit from the turbine runner as a function of discharge

and release elevation.

26

FIG. 10. Average rate of change in pressure during transit of the sensor from wicket gate

passage to exit from the turbine runner as a function of discharge and release

elevation.