U.S. Fire Administration/Technical Report Series

Fire at Watts Bar

Hydroelectric Plant

Rhea County, Tennessee

USFA-TR-147/September 2002

Homeland

Security

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Fire at Watts Bar

Hydroelectric Plant

Authored by: Jennifer L. Roberson

Hollis Stambaugh

This is Report 147 of the Major Fires Investigation Project conducted 

by Varley-Campbell and Associates, Inc./TriData Corporation under 

contract EMW-97-C0-0506 to the United States Fire Administration, 

Federal Emergency Management Agency.

Homeland

Security

Department of Homeland Security

United States Fire Administration

National Fire Data Center

U.S. Fire Administration

Mission Statement

As an entity of the Department of Homeland 

Security, the mission of the USFA is to reduce life and economic losses due to fire 

and related emergencies, through leadership, advocacy, coordination, and support. 

We serve the Nation independently, in coordination with other Federal agencies, 

and in partnership with fire protection and 

emergency service communities. With a 

commitment to excellence, we provide public education, training, technology, and data 

initiatives.

Homeland

Security

ACKNOWLEDGMENTS

The U.S. Fire Administration greatly appreciates the cooperation received from the following people 

and organizations during the preparation of this report:

U.S. Tennessee David J. Icove, P.E., TVA Police

Valley Authority (TVA) Thomas K. Heffernan, Safety, Transmission Power Supply, TVA

H. Lee Hustead, Training Supervisor, TVA

Rhea County Billy Cranfield, Rhea County Emergency Manager

Emergency

Management

Wolf Creek Fire Department

Spring City Fire Department

Evensville Fire Department

Table of Contents

Executive Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Summary of Key Issues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Building Structure and Site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Incident Narrative. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Injuries and Fatalities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

The Investigation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Damage Assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Key Issues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Building Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Fire Protection Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Communications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Risk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Pre-planning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Training. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Power Generation and Terminal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Compliance with Life Safety Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Fire Origin and Spread. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Lessons Learned. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

1

Executive Summary

On September 27, 2002, at approximately 8:30 a.m., the Rhea County, Tennessee 9-1-1 Center began 

receiving calls about a fire at the Watts Bar Hydroelectric Plant. The plant, built between 1939-42 

and operated by the U.S. Tennessee Valley Authority (TVA), is constructed of steel and concrete, and 

sits on the Tennessee River midway between Knoxville and Chattanooga. The dam supplying water 

to the hydroelectric plant is 112 feet high, and approximately one-half mile long. The plant has a 

generating capacity of 175,000 kilowatts. It supplies power for TVA, and provides back-up power 

for the Watts Bar Nuclear Power Station located directly south of dam.

At the time of ignition—estimated to be 8:15 a.m.—there were five employees working in the 

hydroelectric plant control room. The fire spread rapidly, giving these personnel only four minutes 

to realize that there was a fire and to escape. All five were able to evacuate the control building, 

although each employee suffered smoke inhalation. There were no injuries.

The first call concerning the fire was made by a water delivery man who was at the control building. 

A second call was made from the Watts Bar Lake Resort located down the street from the plant.

The fire began in the vertical cable shaft and spread so rapidly to the control building and burned so 

intensely that fire suppression personnel were unable to make entry into the building until 9:10 a.m. 

The fire self-extinguished due to lack of fuel at some point, although investigators could not determine precisely when this occurred. The intensity of the heat generated during the fire prevented 

firefighters from accessing the seat of the fire until 12:17 p.m. In all, over forty personnel from both 

volunteer and industrial fire departments responded to the fire.

A multi-agency investigation team lead by the TVA Police began the origin and cause investigation on 

the following day, September 28th. Based upon physical evidence, the area of origin was determined 

to be within a 120-foot vertical cable shaft running from the hydroelectric plant to the control building. Fire modeling was then used to determine fire development and spread, and to estimate the 

temperature of the fire. The hydroelectric plant has remained closed since the fire, at a business loss 

of approximately $100,000 per day.

Although many people perceive a steel and concrete structure as not being a fire risk, this fire illustrated, once again, that a fire in an electrical system can quickly be life-threatening regardless of the 

structure type.

Fire at Watts Bar

Hydroelectric Plant

September 27, 2002
2

Summary of Key Issues

Issue Comments

Building Structure The concrete and steel construction of the building trapped heat, elevating temperatures. In addition, the plant had a constant breezes flowing through it, from the dam 

up through the control building. Five people nearly became trapped due to their 

location in the building, rapidity of fire development, and difficulty of egress.

Fire Protection Systems There were no fire suppression systems within the control building. The annunciator 

alarm wires were severed as a result of the fire.

Communications Due to topography, there was very little radio reception. Moreover, radios for the 

Watts Bar Nuclear Power Station fire brigade must maintain a weak signal due to 

the power station. Most decisions and communications were face-to-face. Once the 

cables in the shaft were cut, communication with personnel in the powerhouse was 

lost. Employees there were unaware of fire in the control building.

Risk The potential for a fatality was great, both within the control building and the powerhouse. Injuries to personnel in the powerhouse were prevented because a senior 

supervisor had a flashlight and led the employees to safety.

Pre-planning Local responders had no pre-plans, and had never been through the building except 

as tourists. Emergency plans for the building were kept in the building, and as a 

result were inaccessible to responders.

Training for Response Personnel Local responders and WBN fire brigade personnel were unfamiliar with tactics for 

fighting a fire in this type of structure. Additionally, firefighters were unfamiliar with 

TVA tactics for fighting electrical fires.

Power Generation and Transmission There was uncertainty about whether some areas of the building were still electrically 

charged. In fact, while power to the structure had been cut, the batteries retained 

their charge for another full day.

Compliance with Life Safety Code WBH had been grandfathered in under the Life Safety Code, and so was non-compliant. This is now being addressed by TVA.

Building Structure and Site

The Watts Bar Hydroelectric Plant is located at mile marker 529.9 of the Tennessee River, sitting halfway between Knoxville and Chattanooga, in Rhea County. It is one of nine TVA dams located on the 

river, and has been in continuous service since it opened in 1942. Originally constructed to provide 

power to Oak Ridge Laboratories and the public, and flood control for the Tennessee Valley, the plant 

still provides those services along with backup power to the Watts Bar Nuclear Power Station and 

cooling water for the reactor. The plant is bordered to the north by State Road 68, to the West and 

South by the Watts Bar Nuclear Power Station complex, and to the East by the Tennessee River and 

Miegs County. The hydroelectric plant consists of a powerhouse, a control building, and a switchyard. The hydroelectric plant sits adjacent to the Watts Bar Nuclear Power Station, the two facilities 

are operated by different TVA department.

The hydroelectric powerhouse sits directly on the Tennessee River, and consists of five 30,000-kilowatt unites. Water is fed directly into turbines to generate power, while excess water flows through 

sluice gates connected to the powerhouse. Power created by these units is fed from the powerhouse 

to the control building and the switchyard via copper cables covered in butyl rubber insulation. The 

cables run directly from the generators to the switchyard by way of an L-shaped cable shaft. The shaft 
USFA-TR-147/September 2002 3

runs horizontally west from the generators for approximately 

200’, then runs vertically from the powerhouse to the control 

building and cable switchyard through a 120’ shaft. The tunnels 

are constructed of concrete, with cable trays lining the walls on 

both sides of the horizontal shaft. The five generator leads are 

carried through a concrete conduit located on the floor in the 

middle of the horizontal shaft. The diagram to the right shows a 

cross-section of the horizontal shaft.

Ten platforms are located in the vertical cable shaft. The platforms are made of steel grating, and are spaced vertically at tenfoot intervals. The platforms can be used to visually inspect the 

cables, and to perform maintenance. Platforms are accessed and 

connected by steel ladders—one ladder connects two platforms, 

with ladders on alternating sides of the shaft as they ascend.

More specifically, the cable shaft contained several types of electrical 

cable, including:

• Generator leads for five hydroelectric units consisting of two 1750 MCM (Thousand Circular 

Mils) diameter cable per phase running in conduit and a concrete duct bank at the west end 

of the shaft.

• One set of 480V cable running from two separate 480V Main Auxiliary buses with 1000 

MCM cable per phase running up both the north and south sides of the shaft;

• Two sets 250V DC “00” cable running up both the north and south sides of the shaft;

• Over 150 multi-conductor instrument and control cable at the east end of the shaft;

• Telephone cable; and

• Annunciator fiber optic cables.

Prior to the fire, the cables running through the shaft were coated in a variety of substances, including the previously mentioned butyl rubber and polyvinyl chloride (PVC). The 480V cables were 

mounted in the shaft using wood blocks to prevent their contact with the metal platforms. Running 

parallel to the cable shaft is a visitor’s elevator. Before the fire, the elevator was used to show visitors 

the powerhouse as a part of their tour of the plant. At the time of the fire, there were no visitors at 

the plant.

The control building is located on the south side of State Road 68 on a cliff above the powerhouse, 

and consists of a visitor’s center, control room, terminal room, cable spreading room, and other 

smaller areas. The building consists of two main levels: the control room level and the terminal room 

level. Prior to the fire, the control room level was accessible via a pedestrian overpass from the north 

parking lot, and consisted of several large windows overlooking the Tennessee River and the powerhouse. The terminal level was accessible via stairs from the control room level, or through a door 

from the south western side of the building. Entrance from that point was offset –people entering 

through the southwest doors would find themselves on a landing between the two floors, with a half 

flight of stairs leading up or down. The terminal room level also had several small windows, located 

along the top of the east side of the building and directly next to the southwestern door.

TVA departments.

The hydroelectric powerhouse sits directly on the Tennessee River, and consists of five 

30,000-kilowatt units. Water is fed directly into turbines 

to generate power, while excess water flows through

sluice gates connected to the powerhouse. Power created

by these units is fed from the powerhouse to the control

building and the switchyard via copper cables covered in 

butyl rubber insulation. The cables run directly from the 

generators to the switchyard by way of an L-shaped cable

shaft. The shaft runs horizontally west from the 

generators for approximately 200’, then runs vertically

from the powerhouse to the control building and cable

switchyard through a 120’shaft. The tunnels are

constructed of concrete, with cable trays lining the walls

on both sides of the horizontal shaft. The five generator

leads are carried through a concrete conduit located on the 

floor in the middle of the horizontal shaft. The diagram to 

the right shows a cross-section of the horizontal shaft. 

Ten platforms are located in the vertical cable shaft. The platforms are made of steel

grating, and are spaced vertically at ten-foot intervals. The platforms can be used to visually

inspect the cables, and to perform maintenance. Platforms are accessed and connected by steel

ladders—one ladder connects two platforms, with ladders on alternating sides of the shaft as they

ascend.

2

Cross-section of the 

horizontal cable shaft
4

View of the Control Building from the Dam

View of the Control Building from across Route 68 

The tops of the elevator and cable shafts were also located within the control building.

The tops of both shafts contained machinery not only for the operation of the elevator, but also to 

hoist or lower cables and steel platforms. Below the terminal level was the cable spreading

room. It was here that the cables terminated their vertical ascension and once again began to run 

4

View of the Control Building from 

the Dam

View of the Control Building from the Dam

View of the Control Building from across Route 68 

The tops of the elevator and cable shafts were also located within the control building.

The tops of both shafts contained machinery not only for the operation of the elevator, but also to 

hoist or lower cables and steel platforms. Below the terminal level was the cable spreading

room. It was here that the cables terminated their vertical ascension and once again began to run 

4

View of the Control Building from across Route 68

View of the Control Building from the Dam

View of the Control Building from across Route 68 

The tops of the elevator and cable shafts were also located within the control building.

The tops of both shafts contained machinery not only for the operation of the elevator, but also to 

hoist or lower cables and steel platforms. Below the terminal level was the cable spreading

room. It was here that the cables terminated their vertical ascension and once again began to run 

Watts Bar Hydroelectric Plant Control Building
USFA-TR-147/September 2002 5

The tops of the elevator and cable shafts were also located within the control building. The tops of 

both shafts contained machinery not only for the operation of the elevator, but also to hoist or lower 

cables and steel platforms. Below the terminal level was the cable spreading room. It was here that 

the cables terminated their vertical ascension and once again, began to run horizontally. Contained 

in this room was a small flight of stairs, which could be used by an engineer or other employee to 

inspect the cables before they ran underground into the cable switchyard.

Due to the hydraulic properties of the site, a constant breeze flows from the powerhouse floor, 

through the cable and elevator shafts, to the control building. At a minimum, this breeze is 1/8 miles 

per hour—any fluctuation in wind speed outside the structure increases the velocity of the breeze. 

The chimney effect resulting from this natural phenomenon contributed significantly to the fire 

development and spread. On the day of the fire, the wind speed outside the plant was 16 mph.

horizontally. Contained in this room was a small flight of stairs, which could be used by an 

engineer or other employee to inspect the cables before they ran underground into the cable 

switchyard.

Due to the hydraulic properties of the site, a constant breeze flows from the powerhouse 

floor, through the cable and elevator shafts, to the control building. At a minimum, this breeze is 

1.8 miles per hour--any fluctuation in wind speed outside the structure increases the velocity of

the breeze. The chimney effect resulting from this natural phenomenon contributed significantly

to the fire development and spread. On the day of the fire, the wind speed outside the plant was

16 mph. 

5

Side view of the Watts Bar Hydroelectric Plant
6

Incident Narrative

At approximately 8:15 a.m. September 27, 2002, a phase-ground-phase fault occurred from two 

480 Volt AC power cables and a steel grating located in a vertical concrete cable shaft. The control 

cables carried power from the powerhouse to the control building for normal operation of the plant 

and the plant equipment. As previously described, the control cables (located at water level), traveled up to a cable separating room and the switchyard by means of a 120-foot vertical shaft. The 

electrical fire started in the vertical shaft and rapidly became a ventilation-based fire, which was fed 

by the large number of cables and the constant breeze running through the shaft. According to the 

National Weather Service, weather conditions on the day of the fire were; temperature of 72 degrees 

F, humidity 83%, and a wind speed of 16 mph.

At 8:24 a.m., the Watts Bar Hydroelectric Plant Line 

“A” tripped, indicating that something was wrong 

within the plant. At approximately the same time, 

five workers who were located directly above the 

cable shaft noticed smoke. In the four minutes it 

took workers to evacuate, fire conditions worsened, 

and smoke spread throughout the building. The 

workers successfully exited the building despite 

suffering from the effects of smoke inhalation.

Since the fire intensified so quickly, and it was 

imperative to evacuate immediately, workers were 

not able to all 9-1-1 or the plant prior to fleeing. 

The first 9-1-1 call was made by a water deliveryman who notified his dispatcher of the fire, and 

requested that they call 9-1-1. A second call was made to the Rhea County 9-1-1 center by a Watts 

Bar employee. Rhea County began receiving these calls at 8:30 a.m. The Rhea County Emergency 

Manager was notified of the fire at 8:31 a.m. Watts Bar Nuclear Power Station, located directly south 

of the Hydroelectric Plant, dispatched members of their Fire Protection Unit to assist with fire suppression activities at approximately the same time.

At 8:35 a.m., units from Wolf Creek Fire Department and Spring City Fire Department arrived on the 

scene at the southwestern side of the control building. Simultaneously, the fire brigade from TVA’s 

Watts Bar Nuclear Power Station arrived at the north parking lot with their Tele-squirt. The fire brigade immediately requested additional off-site assistance, with the result that units from Pine Grove 

Fire and Evensville Fire Department responded to the scene.

The units on-scene were informed that the hydrants located in the plant switchyard were inoperable, and that water supply would be drawn from hydrants located directly off State Road 68. 

500’ of 5” supply line was laid from the Tele-squire in the north parking lot to a hydrant on the 

State road. The Tele-squirt then supplied a 3” line laid from the apparatus to the north end of the 

pedestrian footbridge. Running off the 3” line were two 1 3⁄4” attack lines. In addition, units from 

Pine Grove Fire Department had laid 900’ of 5” supply line from a hydrant on the northwest side 

of the switchyard to one of their engines on the south side of the building. This engine supplied 

a 2 1⁄2” line to a wye, which then fed two uncharged l-1/2” attack lines. Water supply was successfully established at 9:10 a.m.

(located at water level), traveled up to a cable separating room and the switchyard by means of a 

120-foot vertical shaft. The electrical fire started in the vertical shaft and rapidly became a

ventilation-based fire, which was fed by the large number of cables and the constant breeze

running through the shaft. According to the National Weather Service, weather conditions on the 

day of the fire were temperature of 72 °F, humidity 83%, and a wind speed of 16 mph. 

At 8:24 a.m., the Watts Bar Hydroelectric Plant Line “A” tripped, indicating that

something was wrong within the plant. At approximately the same time, five workers who were

located directly above the cable shaft noticed smoke. In the four minutes it took workers to 

evacuate, fire conditions worsened, and smoke spread throughout the building. The workers

successfully exited the building despite suffering from the effects of smoke inhalation.

Since the fire intensified so quickly, and it was 

imperative to evacuate immediately, workers were not 

able to call 911 or the plant prior to fleeing. The first

911 call was made by a water deliveryman who notified

his dispatcher of the fire, and requested that they call

911. A second call was made to the Rhea County 911 

center by a Watts Bar employee. Rhea County began

receiving these calls at 8:30 a.m. The Rhea County

Emergency Manager was notified of the fire at 8:31 

a.m. Watts Bar Nuclear Power Station, located directly

south of the Hydroelectric Plant, dispatched members of 

their Fire Protection Unit to assist with fire suppression

activities at approximately the same time.

Control building and switchyard, looking southeast on

Highway 68

6

Control building and switchyard, looking 

southeast on Highway 68
USFA-TR-147/September 2002 7 Site Diagram and Apparatus 

Location

1. Control Building2. Powerhouse3. Location of Watts Bar Nuclear Power Station Tele-Squirt4. Location of volunteer units5. Location of Hydrant 16. Location of Hydrant 2
8

Initial entry into the control building was made 

at 9:11 a.m. Attack crews crossed the pedestrian 

footbridge on the north side of the building, and 

made entry into the control building via the control room. Fire personnel used a thermal imaging 

camera to locate the seat of the fire, and attacked 

the fire using a 1-3/4” attack line. Due to the 

severity of the heat, however, firefighters backed 

out of the building at 9:20 a.m. and an alternative 

attack strategy was developed. A second attack was 

attempted upon the order of the Watts Bar Nuclear 

Power Station unit commander, who at the time was 

functioning as the Incident Commander. At 9:35 

a.m., the two 1-1/2” attack lines running from the 

Pine Grove engine were charged and advanced on 

the southwest door. Firefighters forced entry through the door at 10 a.m. and proceeded to knock 

down a small amount of fire before backing out due to the heat. After this attack, firefighters from 

Watts Bar Nuclear Power Station hydraulically ventilated the visitor’s center/control room using a 

1-3/4” hand line, and then a smoke ejector. During ventilation, three firefighting teams of two personnel each rotated the fire attack through the southwest door, with each team making three attacks 

and further knocking down the fire.

Personnel from the TVA Sequoyah Nuclear Power 

Station (SQN), located outside of Chattanooga, arrived 

on-scene at 10:47 a.m. reported to the unified command post in the north parking lot, and immediately 

began assisting with fire suppression. Since Federal 

regulations governing fire protection of nuclear power 

plants limit the amount of time that scheduled fire 

personnel can be off-site, firefighters from the Watts 

Nuclear Power Station Fire Protection Unit were 

required to return to their posts within two hours. 

Likewise, at 11:45 a.m., personnel from the Watts Bar 

Nuclear Power Station Fire Brigade returned to the 

Nuclear Power Station. At this time, incident command was transferred from the Watts Bar Nuclear Power Station Fire Brigade to the Rhea County 

Emergency Manager.

At 11:50 a.m., personnel made entry to the Terminal Room, believed at that point to be the seat of the 

fire. Attack crews extinguished three fires in the cables and terminal boards, and exited at 12:05 p.m. 

Even with continuing ventilation, heat in the room remained overwhelming. In order to improve 

ventilation, the west exterior windows of the building were removed. Crews then re-entered the 

control room, extinguished a small fire in the relay board, and vented into the visitor gallery by 

breaking a large window separating the two rooms. Crews exited the building at 12:30 p.m.

To release the heat from below the control building, crews re-entered the building at 12:50 p.m. 

to open the hatch to the cable shaft. The crew exited the building after successfully completing 

their mission at 1:09 p.m. Further reconnaissance of the building was required to determine fire 

Ventilation attempt on the southwest side 

of the building

northwest side of the switchyard to one of their engines on the south side of the building. This 

engine supplied a 2-1/2” line to a wye, which then fed two uncharged 1-1/2” attack lines. Water

supply was successfully established at 9:10 a.m. 

Initial entry into the control building was

made at 9:11 a.m. Attack crews crossed the 

pedestrian footbridge on the north side of the 

building, and made entry into the control

building via the control room. Fire personnel

used a thermal imaging camera to locate the seat

of the fire, and attacked the fire using a 1-3/4”

attack line. Due to the severity of the heat,

however, firefighters backed out of the building

at 9:20 a.m., and an alternative attack strategy

was developed. A second attack was attempted

upon the order of the Watts Bar Nuclear Power Station unit commander, who at the time was 

functioning as the Incident Commander. At 9:35 a.m., the two 1-1/2” attack lines running from

the Pine Grove engine were charged and advanced on the southwest door. Firefighters forced

entry through the door at 10:00 a.m. and proceeded to knock down a small amount of fire before

backing out due to the heat. After this attack, firefighters from Watts Bar Nuclear Power Station

hydraulically ventilated the visitor’s center/control room using a 1-3/4” hand line, and then a

smoke ejector. During ventilation, three firefighting teams of two personnel each rotated the fire

attack through the southwest door, with each team making three attacks and further knocking

down the fire.

Ventilation attempt on the southwest side of the

building

8

h Nuclear

m., 

he north 

ing with 

s

er plants

re

m the 

otection 

 within two hours. Likewise, at 11:45 a.m., personnel 

n Fire Brigade returned to the Nuclear Power Station.

ferred from the Watts Bar Nuclear Power Station Fire

Manager.

Command personnel meeting to discuss

strategy

try to the Terminal Room, believed at that point to be 

shed three fires in the cables and terminal boards, and 

g ventilation, heat in the room remained overwhelming.

exterior windows of the building were removed. Crews

ished a small fire in a relay board, and vented into the 

w separating the two rooms. Crews exited the building

e control

Command personnel meeting to 

discuss strategy
USFA-TR-147/September 2002 9

spread. At 1:20 p.m., an attack crew was directed to enter the 

building, advance to the cable spreading room, and if possible, 

check the battery room. The crew was able to advance to the 

cable spreading room where they found a small fire on a cable 

reel, smoldering fires in filing cabinets, and almost complete 

burnout. The attack line was not long enough to reach the 

room, so firefighters used hose from the damaged hose rack to 

extinguish the cable reel fire. Once the fire was extinguished, 

firefighters checked the lower battery room, but were unable 

to determine the extent of damage. They then checked the 

cable tunnel and found severe fire damage in the first fifteen 

feet. Firefighters were forced to leave the building at 1:40 p.m. 

when their SCBA alarms activated.

At 1:42, the TVA Public Information Officer was informed that 

the fire was extinguished and overhaul was in progress. Unit 

commanders met to discuss their course of action, while personnel checked the Control Room level for further fire and 

performed additional ventilation. A crew checked the terminal 

room level for fire at 2:15 p.m., and found only small spot fires 

burning. At 2:25 p.m., crews began systematic entries into the 

building to perform overhaul and cool the structure as much 

as possible. At 3:15 p.m., crews again checked all floors of the 

building and the cable tunnel to see that there were no further 

fires and that the areas were cooling. An additional check for 

spot fires in the cable spreading room was conducted at 3:45 

p.m. No fires were found, and crews reported that areas of the building were cooling off.

Interior operations were concluded at 4:00 p.m. At 4:20 p.m., 

fire personnel, Watts Bar Nuclear Power Station Fire Brigade, 

Sequoyah Nuclear Power Station fire brigade, and fire investigation personnel from TVA met to determine scene security 

issues. One fire engine from Rhea County remained on-scene 

throughout the night in the event that additional fires might 

flare up.

Injuries and Fatalities

Five personnel working in the control building at the time of the 

fire suffered from smoke inhalation and two were transported to 

local hospitals. Upon the arrival of fire personnel, the building 

had been completely evacuated. No fire personnel were injured during fire suppression, overhaul, or 

investigation activities. Fire and investigation personnel were quick to point out that there could have 

been more injuries had the fire occurred later in the day. Had visitors been using the elevator at the 

time of the fire, they would have had no means of escape. Fire personnel also stated that the length 

of time it took to gain entry to the control building most likely helped prevent injuries. According to 

several firefighters, if they had been able to reach the terminal room on their first try, they would have 

been in very serious trouble from the heat and the amount of fire present.

then re-entered the control room, extinguished a small fire in a relay board, and vented into the 

visitor gallery by breaking a large window separating the two rooms. Crews exited the building

at 12:30 p.m. 

To release the heat from below the control

building, crews re-entered the building at 12:50 p.m. to 

open the hatch to the cable shaft. The crew exited the

building after successfully completing their mission at

1:09 p.m. Further reconnaissance of the building was

required to determine fire spread. At 1:20 p.m., an attack 

crew was directed to enter the building, advance to the

cable spreading room, and if possible, check the battery

room. The crew was able to advance to the cable

spreading room where they found a small fire on a cable reel, smoldering fires in filing cabinets, 

and almost complete burnout. The attack line was not long enough to reach the room, so the 

firefighters used hose from the damaged hose rack to extinguish the cable reel fire. Once the fire

was extinguished, firefighters checked the lower battery room, but were unable to determine the

extent of damage. They then checked the cable tunnel and found severe fire damage in the first

Briefing prior to first entry to cable gallery

9

Briefing prior to first entry to 

fifteen feet. Firefighters were forced to leave the building at 1:40 p.m. when their SCcable gallery BA alarms

activated.

At 1:42, the TVA Public Information Officer was

informed that the fire was extinguished and overhaul

was in progress. Unit commanders met to discuss their

course of action, while personnel checked the Control 

Room level for further fire and performed additional

ventilation. A crew checked the terminal room level

for fire at

2:15 p.m., 

and found 

only small 

spot fires burning. At 2:25 p.m., crews began

systematic entries into the building to perform

overhaul and cool the structure as much as possible.

At 3:15 p.m., crews again checked all floors of the

building and the cable tunnel to see that there were no 

further fires and that the areas were cooling. An 

additional check for spot fires in the cable spreading room was conducted at 3:45 p.m. No fires 

were found, and crews reported that areas of the building were cooling off.

Burned cables, running from the cable tunnel

to the switchyard

Personnel preparing to enter the Control

Building

Interior operations were concluded at 4:00 p.m. At 4:20 p.m., fire personnel, Watts Bar

Nuclear Power Station Fire Brigade, Sequoyah Nuclear Power Station fire brigade, and fire

investigation personnel from TVA met to determine scene security issues. One fire engine from

Rhea County remained on-scene throughout the night in the event that additional fires might

flare up.

Injuries and Fatalities

Five personnel working in the control building at the time of the fire suffered from smoke

inhalation and two were transported to local hospitals. Upon the arrival of fire personnel, the 

building had been completely evacuated. No fire personnel were injured during fire suppression,

overhaul, or investigation activities. Fire and investigation personnel were quick to point out that 

there could have been more injuries had the fire occurred later in the day. Had visitors been

using the elevator at the time of the fire, they would have had no means of escape. Fire

personnel also stated that the length of time it took to gain entry to the control building most 

Burned cables, running from the 

cable tunnel to the switchyard

fifteen feet. Firefighters were forced to leave the building at 1:40 p.m. when their SCBA alarms

activated.

At 1:42, the TVA Public Information Officer was

informed that the fire was extinguished and overhaul

was in progress. Unit commanders met to discuss their

course of action, while personnel checked the Control 

Room level for further fire and performed additional

ventilation. A crew checked the terminal room level

for fire at

2:15 p.m., 

and found 

only small 

spot fires burning. At 2:25 p.m., crews began

systematic entries into the building to perform

overhaul and cool the structure as much as possible.

At 3:15 p.m., crews again checked all floors of the

building and the cable tunnel to see that there were no 

further fires and that the areas were cooling. An 

additional check for spot fires in the cable spreading room was conducted at 3:45 p.m. No fires 

were found, and crews reported that areas of the building were cooling off.

Burned cables, running from the cable tunnel

to the switchyard

Personnel preparing to enter the Control

Building

Interior operations were concluded at 4:00 p.m. At 4:20 p.m., fire personnel, Watts Bar

Nuclear Power Station Fire Brigade, Sequoyah Nuclear Power Station fire brigade, and fire

investigation personnel from TVA met to determine scene security issues. One fire engine from

Rhea County remained on-scene throughout the night in the event that additional fires might

flare up.

Injuries and Fatalities

Five personnel working in the control building at the time of the fire suffered from smoke

Personnel preparing to enter the 

Control Building
10 U.S. Fire Administration/Technical Report Series

By the time fire suppression operations were concluded, over forty fire and medical personnel had 

responded to the scene. Unites from the Watts Bar Nuclear Power Station Fire Brigade, Wolf Creek 

Fire Department, Sequoyah Nuclear Power Station Fire Brigade, Evensville Fire Department, Pine 

Grove Fire Department Stations 1 and 2, Spring City Fire Department, Miegs County, and Rhea 

County Emergency Medical Services had worked together to ensure the successful extinguishment 

of the blaze.

Investigation into the origin and cause of the fire began the next morning, September 28.

The Investigation

As soon as the control building was determined to be safe, a multi-agency investigation team lead by 

the TVA Police began their origin and cause determination. The team consisted of investigators from 

the Bureau of Alcohol, Tobacco and Firearms, Knox County Sheriff’s Department, TVA Office of the 

Inspector General, and TVA Police. Of top priority was ensuring that the fire was not the result of a 

deliberate act. Investigators prepared a preliminary report, which was released in November 2002. 

The report concluded that the fire was initially caused by a phase-ground-phase fault between one 

of the 480V cables running from the 480V main buses, and presented the results of a fire model run 

by the TVA Police.

Based on damage to the cables and the steel decking, investigators 

concluded that prolonged rubbing of the steel decking against the 

butyl rubber insulation on the cable had resulted in a breaching 

of the cable insulation at the number five level (roughly 60 feet 

above ground) in the cable shaft. This resulted in an arc from the 

cables to the decking, and back to the cable. The extreme temperature generated by this arc was enough to cause a small amount of 

the insulation to deteriorate into a flammable substance, thereby 

resulting in ignition. The large quantity of flammable materials in 

the shaft, coupled with a continuous chimney effect, provided the 

small fire with enough fuel to self-sustain and free burn. Within 

a matter of seconds, the fire started to spread rapidly. The high 

flammability of the insulation surrounding the cabling magnified 

the speed of propagation. Those cables which were covered with PVC released polyvinylchloride gas 

as they burned.

The construction of the cable shaft and the Control Building also helped the fire. The solid construction of the building trapped heat inside the structure, resulting in severe spalling within the cable 

spreading room, and causing temperatures on the terminal room and control room levels to skyrocket, even without visible flame. Based on the results of a fire model run by TVA Police, and using 

data from the United States Fire Administration, the National Institute of Standards and Technology, 

and the Nuclear Regulatory Commission, it was determined that temperatures within the control 

building reached or exceeded 1,200 degrees F during the fire. The heat generated in the shaft was 

so intense that steel decking 60 feet below the area of origin was severely warped, while water used 

during the first hours of attack instantly boiled on the floor of the structure or turned to steam.

Heat, smoke and flame generated by the initial fire traveled up the cable shaft, hitting their first 

obstacle in the cable spreading room. The sudden change in direction, lack of flammables, and 

compression of space could have smothered the fire. However, due to the advanced stage of the 

Point of fire origin

THE INVESTIGATION

As soon as the control building was determined to be safe, a multi-agency

investigation team lead by the TVA Police began their origin and cause determination. The 

team consisted of investigators from the Bureau of Alcohol, Tobacco and Firearms, Knox

County Sheriff’s Department, TVA Office of the Inspector General, and TVA Police. Of top 

priority was ensuring that the fire was not the result of a deliberate act. Investigators prepared

a preliminary report, which was released in November 2002. The report concluded that the 

fire was initially caused by a phase-ground-phase fault between one of the 480V cables 

running from the 480V main buses, and presented the results of a fire model run by the TVA 

Police.

Based on damage to the cables and the 

steel decking, investigators concluded that 

prolonged rubbing of the steel decking against

the butyl rubber insulation on the cable had

resulted in a breaching of the cable insulation at

the number five level (roughly 60 feet above 

ground) in the cable shaft. This resulted in an 

arc from the cables to the decking, and back to

the cable. The extreme temperature generated

by this arc was enough to cause a small amount 

of the insulation to deteriorate into a flammable substance, thereby resulting in ignition. The 

large quantity of flammable materials in the shaft, coupled with a continuous chimney effect,

provided the small fire with enough fuel to self-sustain and free burn. Within a matter of 

seconds, the fire started to spread rapidly. The high flammability of the insulation

surrounding the cabling magnified the speed of propagation. Those cables which were

covered with PVC released polyvinilchloride gas as they burned.

Point of fire origin

The construction of the cable shaft and the Control Building also helped the fire. The

solid construction of the building trapped heat inside the structure, resulting in severe spalling

within the cable spreading room, and causing temperatures on the terminal room and control 

room levels to skyrocket, even without visible flame. Based upon the results of a fire model 

run by TVA Police, and using data from the United States Fire Administration, the National 

Institute of Standards and Technology, and the Nuclear Regulatory Commission, it was 

determined that temperatures within the control building reached or exceeded 1,200o F during

12
USFA-TR-147/September 2002 11

fire, it continued several feet down the cable channels into 

the switchyard and damaged cables as far as one hundred feet 

from the control building. In addition, the fire spread into 

the terminal level, igniting the fire load in the terminal room, 

with the result that firefighters initially considered it to be 

the room of origin and therefore the primary target of their 

attack. The smoke and the heat further penetrated the control 

room level, damaging everything on that level and causing 

further fires. Effects below the fire consisted of severe heat 

and smoke damage.

Damage Assessment

Although the fire occurred in a vertical shaft, there was a significant amount of damage to all parts of the hydroelectric 

plant. All cables running through the shaft were destroyed 

and severed as a result of the fire, resulting in a loss of communications, fire annunciation systems, and most importantly, 

power transmission. Additionally, the ladders and steel decking in the vertical shaft were warped. 

The cable spreading room above the shaft sustained significant 

spalling and smoke damage. The control building sustained 

significant damage, both from the effects of the fire and the effort associated with its extinguishment. 

Items within the building, including records, files, desks, 

breathing apparatus, and power control stations, were irrevocably damaged by the fire. In an effort to ventilate the building and reach the fire, firefighters forced doors and broke 

windows. Overhaul of the site resulted in further damage, as 

firefighters pulled ceilings and breached walls to ensure the 

fire was completely out. Water damage was also extensive, 

due to the significant volume of water necessary to cool the 

structure and extinguish the fire.

Due to the destruction of the power transmission cables, the 

generators had to be shut down. In order to prevent flooding 

upriver from the dam and to ensure that there was enough 

water flowing downstream to provide cooling for the Watts Bar Nuclear Power Station, the floodgates 

had to be opened. The closure of the generators and the opening of the floodgates have resulted in a 

significant loss of revenue for TVA. Estimates place the daily loss of revenue at up to $100,000.

the fire. The heat generated in the shaft was so intense that steel decking 60 feet below the

area of origin was severely warped, while water used during the first hours of attack instantly

boiled on the floor of the structure or turned to steam.

Heat, smoke, and flame generated by the initial

fire traveled up the cable shaft, hitting their first

obstacle in the cable spreading room. The sudden 

change in direction, lack of flammables, and 

compression of space could have smothered the fire.

However, due to the advanced stage of the fire, it 

continued several feet down the cable channels into 

the switchyard and damaged cables as far as one 

hundred feet from the control building. In addition, 

the fire spread into the terminal level, igniting the fire

load in the terminal room, with the result that

firefighters initially considered it to be the room of 

origin and therefore the primary target of their attack.

The smoke and the heat further penetrated the control

room level, damaging everything on that level and

causing further fires. Effects below the fire consisted

of severe heat and smoke damage.

Warped decking below the area of origin

Damage Assessment

Although the fire occurred in a vertical shaft, there was a significant amount of 

damage to all parts of the hydroelectric plant. All cables running through the shaft were

destroyed and severed as a result of the fire, resulting in a loss of communications, fire

annunciation systems, and most importantly, power transmission. Additionally, the ladders

and steel decking in the vertical shaft were warped.

Control Building, approximately two hours into

the fire 

The cable spreading room above the shaft 

sustained significant spalling and smoke damage.

The control building sustained significant damage,

both from the effects of the fire and the effort

associated with its extinguishment. Items within 

the building, including records, files, desks, 

13

Warped decking below the area 

of origin

, and 

ered the fire.

the fire, it 

hannels into 

ar as one 

In addition, 

gniting the fire

lt that

he room of 

of their attack.

ed the control

at level and

 fire consisted

Warped decking below the area of origin

vertical shaft, there was a significant amount of 

plant. All cables running through the shaft were

fire, resulting in a loss of communications, fire

antly, power transmission. Additionally, the ladders

ere warped.

Control Building, approximately two hours into

the fire 

e the shaft 

e damage.

nt damage,

 effort

ms within 

sks, 

13

Control Building, approximately 

two hours into the fire
12 U.S. Fire Administration/Technical Report Series

Key Issues

Building Structure

The Watts Bar Hydroelectric plant was constructed 

of concrete and steel, and located directly on the 

Tennessee River. The plant was essentially a bunker, with very few windows on the powerhouse 

floor, and small, sealed, windows in the lower 

levels of the control building. Even the large plateglass windows located on the control room level 

of the control building were unable to be opened; 

their purpose was simply to provide a view of the 

dam for visitors. The building was comprised of 

various levels, connected by one staircase on the 

western side of the building. The layout of the 

building, combined with the limited number of windows, made it a difficult structure to ventilate.

The construction of the hydroelectric plant contributed to heat build-up and distribution. The concrete walls, floors, and ceilings acted as an oven, intensifying the heat and trapping it in the building. 

These conditions made firefighter entry and fire suppression extremely difficult. During fire suppression activities, firefighters reported that the water they were using to fight the fire was turning 

to steam or boiling upon contact with the floor. The level of heat in the building was further evident 

during the post-incident investigation. Investigators found heavy spalling in the cable spreading 

room.

The location of the building on a major body of water is significant for more reasons than power 

generation. Moving water generates a pressure differential within the local atmosphere. As a result, 

a slight breeze is produced. This principle is commonly known as the Venturi Effect. Firefighters 

are familiar with this principle through the practice of hydraulic ventilation – using a hose line to 

ventilate a building by spraying a fog pattern out a window, thereby creating a pressure differential 

and drawing air out of the room. The constant flow of water through the turbines in the powerhouse 

resulted in the Venturi effect in the Watts Bar Hydroelectric plant, with more damaging results. The 

control building was connected to the powerhouse by a vertical shaft, half of which carried cables, 

and half of which served as an elevator for visitors touring the plant. The breeze generated by the 

constant flow of water through the turbines took the path of least resistance, moving from the powerhouse, through the cable shaft, and out the cable trays. This constant, ever-present breeze fed the 

fire in the cable shaft, resulting in rapid fire spread.

Within the hydroelectric plant complex, there are a limited number of egress routes from the control building. On a normal day, in order to exit the building workers on the terminal room level 

are required to walk the length of the building through a variety of rooms and passages in order to 

reach the stairwell. They then have to climb a half-flight of stairs in order to reach the door. Visitors 

and workers on the control room level have easier access to an exit, although there is still only one 

on that level. An alternative exit for personnel on this level is to go downstairs to the exit used by 

personnel on the terminal level.

The day of the fire, firefighters would have had limited access to any personnel who might have 

become trapped on the terminal room level. While there were windows on the east side of the 

KEY ISSUES

Building Structure

The Watts Bar Hydroelectric plant

was constructed of concrete and steel, and

located directly on the Tennessee River.

The plant was essentially a bunker, with 

very few windows on the powerhouse floor,

and small, sealed, windows in the lower 

levels of the control building. Even the 

large plate-glass windows located on the 

control room level of the control building

were unable to be opened; their purpose 

was simply to provide a view of the dam for

visitors. The building was comprised of 

various levels, connected by one staircase on the western side of the building. The layout of 

the building, combined with the limited number of windows, made it a difficult structure to 

ventilate.

View of the control building from the South. Note the

solid concrete construction and lack of windows.

The construction of the hydroelectric plant contributed to heat build-up and

distribution. The concrete walls, floors, and ceilings acted as an oven, intensifying the heat

and trapping it in the building. These conditions made firefighter entry and fire suppression 

extremely difficult. During fire suppression activities, firefighters reported that the water they

were using to fight the fire was turning to steam or boiling upon contact with the floor. The 

level of heat in the building was further evident during the post-incident investigation.

Investigators found heavy spalling in the cable spreading room. 

The location of the building on a major body of water is significant for more reasons

than power generation. Moving water generates a pressure differential within the local 

atmosphere. As a result, a slight breeze is produced. This principle is commonly known as 

the Venturi Effect. Firefighters are familiar with this principle through the practice of

hydraulic ventilation—using a hose line to ventilate a building by spraying a fog pattern out a

window, thereby creating a pressure differential and drawing air out of the room. The 

constant flow of water through the turbines in the powerhouse resulted in the Venturi effect in 

the Watts Bar Hydroelectric plant, with more damaging results. The control building was

15

View of the control building from the South. 

Note the solid concrete construction 

and lack of windows.
USFA-TR-147/September 2002 13

building there, they were small and very thick, making them a poor choice for entry. The only practical way for firefighters to enter this level was through the sole means of egress- -the southwest door. 

In the case of this fire, had any Watts Bar personnel become trapped on the terminal room level—a 

situation that nearly happened—they would have likely become casualties almost immediately.

Fire Protection Systems

The Watts Bar Hydroelectric Plant was constructed before the use of sprinklers were a standard part 

of building construction and was not originally designed to comply with what is the current NFPA 

101 code. Even after the advent of sprinklering, there was little interest in installing sprinklers at 

this point. Conventional wisdom throughout the hydroelectric and the broader power generation community held that the fire risk to hydroelectric plants was minimal, based on their type of 

construction and proximity to water. As a result, retrofitting the building with fire sprinklers or 

suppression systems was not considered necessary. While the powerhouse floor was outfitted with 

a carbon dioxide (CO2) dump system to suppress any fires that might occur in the generators, there 

were no fire suppression systems in the control building. Additionally, there were no detection or 

alarm systems in the control building. There was a detection system in the powerhouse, specifically 

in the hall storage room, generator cabinet, and governor cabinet. This system was connected to an 

annunciator panel in the control room, but the fire had effectively severed the connection rendering 

it inoperable.

Fire suppression services at Watts Bar Hydroelectric Plant are provided through long-standing mutual 

aid agreements with local volunteer fire companies in Rhea and Miegs Counties. While all personnel 

are familiar with these agreements, they are not set forth as formal, written policies. Rather, they are 

simply understood to be the way fire protection assistance is handled. In addition, the fire brigade 

from the Watts Bar Nuclear Station provides assistance when necessary.

Presumptions that hydroelectric power plants were essentially “fireproof” led to a decision in 1993 

to reduce fire suppression personnel and training at the Watts Bar Hydroelectric Plant. For budgetary reasons, TVA decided to remove the on-site fire brigade from the plant and instead train plant 

personnel on incipient firefighting only.

TVA defined incipient fires as those that could be easily extinguished by one person, or a fire roughly 

the sizes of a small trash can fire. While this decision was reasonable based upon previous experience 

with hydroelectric plants, it left a gap in fire protection for the facility. Also missing was a formal 

plan for incorporating volunteer personnel into a fire response team that included or designated a 

command structure in the event of a fire. This lack of planning was evident on the day of the fire 

when personnel were initially unsure of who was responsible for incident command. While that 

uncertainty did not materially affect fire operations in this case, it is a point of concern. TVA, in 

their post-incident analysis, recognized this problem and is taking steps to develop and implement 

an incident management plan. They also have begun comprehensive program to bring all of their 

hydroelectric plants into compliance with the Life Safety Code and to set up fire suppression systems 

with the facilities.

Communications

The location of the Watts Bar Hydroelectric plant had a direct impact on fireground communications. The plant is located in a rural section of Rhea County in a very hilly and heavily wooded area. 

Although there are repeaters throughout Rhea and Miegs Counties, the radio signal in the immedi-
14 U.S. Fire Administration/Technical Report Series

ate vicinity of the plant is still weak. The radios used by local response personnel were useful in 

communicating with other local personnel on the scene, but they did face some difficulty in clearly 

communicating with central dispatch.

Adding to the communications challenge, the fire brigade personnel from the Watts Bar Nuclear Power 

Station have radios with weak signals because material located within the nuclear power station is very 

sensitive to radio signals. Their radios are useful for communicating directly with each other at the 

nuclear power station site, but they have a severely limited range. As a result, fire brigade personnel 

were unable to communicate with the nuclear power station from the hydroelectric plant site.

Some TVA fire brigade personnel have been conducting tests using cell phones with digital walkietalkie capabilities as an alternative to using the 

radios. Several of these personnel were on-scene 

during the fire. However, the radio signal difficulties related to topography applied to the enhanced 

capabilities of cell phone as well. One member of 

the Watts Bar Fire Brigade stated that during the 

fire he found an approximately 10-square foot area 

in the north parking lot where he could use his 

phone. Whenever he needed to communicate with 

his phone, he had to go to this spot to get a signal.

Another difficulty faced by personnel was the lack 

of interoperability of the portable radios. Local 

volunteer departments used one kind of radio, 

while responders from the Watts Bar Nuclear Power Station used another kind of radio that operated 

on a different frequency. Due to these differences, personnel were unable to communicate with each 

other by radio, so on-scene communications among response agencies were made face-to-face.. 

Personnel are aware that using radios is preferable, and local response agencies and the TVA are now 

planning to carry portable radios from the other response agency on their apparatus. In this way, 

Watts Bar Nuclear Power Station fire brigade personnel will have a Rhea County radio for use in an 

emergency, and Rhea County fire apparatus will have a Watts Bar Nuclear Power Station fire brigade 

radio.

There were also communications difficulties within the actual hydroelectric plant. The powerhouse 

and control building are linked via landline. When the fires started in the vertical cable shaft, communication lines between the control building and powerhouse were cut. The result was that personnel in the powerhouse were completely unaware of the fire in the cable shaft, and that people in the 

control building were being evacuated. Due to the constant breeze flowing through the powerhouse, 

all smoke from the fire was directed upwards and away from the powerhouse. The first indication 

that any powerhouse personnel had of a problem was when their power went out as a result of the 

fire. There was no effective backup means of communication to warn workers of the fire and the 

pending need to leave the building. TVA recognized this problem in the after-action analysis of the 

fire, and is working to address it.

Response personnel meeting face-to-face to 

discuss strategy

communicating directly with each other at the nuclear power station site, but they have a 

severely limited range. As a result, fire brigade personnel were unable to communicate with 

the nuclear power station from the hydroelectric plant site.

Some TVA fire brigade personnel

have been conducting tests using cell 

phones with digital walkie- talkie 

capabilities as an alternative to using the

radios. Several of these personnel were onscene during the fire. However, the radio

signal difficulties related to topography

applied to the enhanced capabilities of cell

phone as well. One member of the Watts

Bar Fire Brigade stated that during the fire

he found an approximately 10-square foot 

area in the north parking lot where he could

use his phone. Whenever he needed to communicate with his phone, he had to go to this spot 

to get a signal.

Response personnel meeting face-to-face to discuss

strategy

Another difficulty faced by personnel was the lack of interoperability of the portable 

radios. Local volunteer departments used one kind of radio, while responders from Watts Bar

Nuclear Power Station used another kind of radio that operated on a different frequency. Due 

to these differences, personnel were unable to communicate with each other by radio, so onscene communications among response agencies were made face-to-face. Personnel are 

aware that using radios is preferable, and local response agencies and the TVA are now 

planning to carry portable radios from the other response agency on their apparatus. In this 

way, Watts Bar Nuclear Power Station fire brigade personnel will have a Rhea County radio

for use in an emergency, and Rhea County fire apparatus will have a Watts Bar Nuclear

Power Station fire brigade radio.

There were also communications difficulties within the actual hydroelectric plant. The

powerhouse and control building are linked via landline. When the fire started in the vertical 

cable shaft, communication lines between the control building and powerhouse were cut. The 

result was that personnel in the powerhouse were completely unaware of the fire in the cable

shaft, and that people in the control building were being evacuated. Due to the constant

breeze flowing through the powerhouse, all smoke from the fire was directed upwards and
USFA-TR-147/September 2002 15

Risk

Personnel working within both the control building and the powerhouse faced challenges in exiting during the fire. As described earlier in this report, the layout and design of the control building 

resulted in a limited means of egress for personnel in the control building. In the case of this fire, 

personnel had to pass above the fire to reach the exit. Had there been any significant delay, personnel 

in the building could have been seriously harmed trying to escape.

The design of the powerhouse also contributed 

to existing problems. The building is a large 

windowless structure, with heavy machinery 

and other dangers located throughout. It, too, 

has very limited means of egress, with exits to 

ground level on the west end and an exit to the 

top of the dam on the east end. The powerhouse 

has several levels, both above and below the 

waterline, with exits located on only one level. 

When power to the building was lost, workers 

were plunged into complete darkness. Personnel 

would have had to rely on their knowledge of 

the building and their sense of touch and hearing to exit the building. Luckily, a supervisor on 

the floor had a flashlight, and was able to find people and lead them safely from the building. TVA’s 

review of life safety issues will likely include increased exit lighting per NFPA 101 7.8.1.

While personnel in both buildings had received training on evacuation, evacuation drills are not 

routinely held. Following the fire, TVA accident investigators determined that this was a problem 

that needed to be addressed, and they have recommended frequent training on and demonstrations 

of emergency and evacuation procedures.

Pre-planning

Local response personnel were aware that they would be the first responders to an event at the Watts 

Barr Hydroelectric Plant. Nevertheless, responders were not provided with plant diagrams, nor were 

there any plant pre-plans. Several of the local responders stated that they had only been in the plant 

on the visitor’s tour, and had no idea what else was inside the building.

Control building diagrams were available at the site, stored in filing cabinets on the terminal room 

level. Due to the rapidity of fire spread and the need for quick evacuation, there was no time for 

personnel to grab the plans—they were lost in the fire. As a result, personnel working on-scene 

initially had to rely on employee’s knowledge of the building to plan fire suppression activities and 

ventilation. Watts Bar Nuclear Power Station personnel requested that TVA fax copies of the plans to 

the site; these plans arrived several hours into the incident and were immediately utilized by onscene personnel.

As a result of this fire, TVA and local response agencies are working together to develop comprehensive pre-plans for use in the event of another emergency at the hydroelectric plant. In addition, TVA 

is planning to provide local responders with a tour of the plant: the goal is to make this part of the 

annual training for responders.

Powerhouse floor

Risk

Personnel working within both the control building and the powerhouse faced

challenges in exiting during the fire. As described earlier in this report, the layout and design

of the control building resulted in a limited means of egress for personnel in the control 

building. In the case of this fire, personnel had to pass above the fire to reach the exit. Had 

there been any significant delay, personnel in the building could have been seriously harmed

trying to escape.

The design of the powerhouse also 

contributed to existing problems. The 

building is a large windowless structure, 

with heavy machinery and other dangers

located throughout. It, too, has very

limited means of egress, with exits to

ground level on the west end and an exit to 

the top of the dam on the east end. The 

powerhouse has several levels, both above 

and below the waterline, with exits located

on only one level. When power to the 

building was lost, workers were plunged into complete darkness. Personnel would have had 

to rely on their knowledge of the building and their sense of touch and hearing to exit the 

building. Luckily, a supervisor on the floor had a flashlight, and was able to find people and 

lead them safely from the building. TVA’s review of life safety issues will likely include

increased exit lighting per NFPA 101 7.8.1. 

Powerhouse floor

While personnel in both buildings had received training on evacuation, evacuation

drills are not routinely held. Following the fire, TVA accident investigators determined that

this was a problem that needed to be addressed, and they have recommended frequent training

on and demonstrations of emergency and evacuation procedures.

19
16 U.S. Fire Administration/Technical Report Series

Training

Prior to the fire at the hydroelectric plant, local responders, plant personnel, and the Watts Bar 

Nuclear Power Station fire brigade had not trained together. One of the firefighters from the fire brigade is a volunteer firefighter in Rhea County, but that was the extent of regular interaction among 

the response organizations.

In addition, personnel from the nuclear power station 

and local response agencies were unfamiliar with the 

various tactics necessary to fight a fire in the control 

building of the hydroelectric plant. Local responders 

have been trained to fight the types of fires they are 

most likely to encounter: fires in homes, brush or businesses. Personnel from the nuclear power station have 

been trained to fight fires inside a nuclear power plant. 

While some of the tactics from each type of training can 

be used in fighting a fire in a hydroelectric plant control building, there are still special considerations and 

suppression tactics. Specifically, none of the responders 

were familiar with the special tactics needed to fight a 

fire involving an electrically charged object.

TVA has developed tactics and methods for successfully fighting electrical fires using water. Some 

field personnel are trained on these tactics, and frequently use them to suppress fires. As a result of 

their post incident investigation, TVA recognized the necessity of training local response personnel 

who provide or support on-scene fire suppression in these specialized tactics. The challenge lies 

in finding the time and the funding to provide volunteer responders with this training. Volunteer 

firefighters stated that the best time for them to attend training would be during the weekend, 

when they are not at work. However, TVA stated that providing training on weekends would be a 

financially difficult option, due to the need to provide instructors with overtime pay. TVA and local 

responders are working together on these issues, to ensure that responders receive the appropriate 

specialized training.

Local responders and TVA personnel also recognize the need to train together, in order to become 

familiar with the operating procedures and tactics used by each agency. Responders plan on drilling 

together more frequently and holding training exercises on TVA property.

Power Generation and Terminal

Upon arrival at the control building, TVA and local response personnel were uncertain as to whether 

the hydroelectric plant was still generating power. Due to the fact that the control building is the 

point where power from the hydroelectric plant is distributed to power lines, it was critical to determine if electricity was still flowing through the cables. Additionally, the building housed several 

backup batteries of varying voltage, which were supposed to provide power to the plant in the event 

of a sudden power loss. There was uncertainty during fire suppression operations as to whether 

these batteries had discharged their electricity, or if they were still charged.

Due to the uncertainty concerning the electrical situation, the decision was made by command 

personnel to treat all electrical apparatus within the control building as charged. This proved to be a 

prudent decision as it was discovered during the initial post-incident investigation that the batteries 

indeed were still charged.

Fire in the breaker panels; looking 

from outside the Control Building, 

three hours into the fire. 

In addition, personnel from the 

nuclear power station and local response 

agencies were unfamiliar with the various

tactics necessary to fight a fire in the control

building of the hydroelectric plant. Local

responders have been trained to fight the 

types of fires they are most likely to 

encounter: fires in homes, brush, or 

businesses. Personnel from the nuclear power

station have been trained to fight fires inside a

nuclear power plant. While some of the 

tactics from each type of training can be used in fighting a fire in a hydroelectric plant control

building, there are still special considerations and suppression tactics. Specifically, none of 

the responders were familiar with the special tactics needed to fight a fire involving an 

electrically charged object.

Fire in the breaker panels; looking from outside the

Control Building, three hours into the fire. 

TVA has developed tactics and methods for successfully fighting electrical fires using

water. Some field personnel are trained on these tactics, and frequently use them to suppress 

fires. As a result of their post incident investigation, TVA recognized the necessity of training

local response personnel who provide or support on-scene fire suppression in these 

specialized tactics. The challenge lies in finding the time and the funding to provide volunteer 

responders with this training. Volunteer firefighters stated that the best time for them to 

attend training would be during the weekend, when they are not at work. However, TVA

stated that providing training on weekends would be a financially difficult option, due to the 

need to provide instructors with overtime pay. TVA and local responders are working

together on these issues, to ensure that responders receive the appropriate specialized training.

Local responders and TVA personnel also recognize the need to train together, in 

order to become familiar with the operating procedures and tactics used by each agency.

Responders plan on drilling together more frequently and holding training exercises on TVA 

property.

Power Generation and Terminal

Upon arrival at the control building, TVA and local response personnel were uncertain

as to whether the hydroelectric plant was still generating power. Due to the fact that the

control building is the point where power from the hydroelectric plant is distributed to power 
USFA-TR-147/September 2002 17

Compliance with Life Safety Code

As the hydroelectric plant was finished in the early 1940’s, the building was not originally designed to 

comply with the Life Safety Code (NFPA 101). In addition, there was no requirement that the building 

be retrofitted to meet the code. As a result, egress was severely limited, emergency lighting was not 

provided throughout the facility, and there was no mechanism for remotely activating a fire alarm.

Since the fire, TVA has recognized the importance of bringing all hydroelectric facilities into compliance with the Life Safety Code. While out of service, Watts Bar Hydroelectric Plant is undergoing 

renovations that will bring it into compliance. Additionally, the plant is undergoing comprehensive 

maintenance on all equipment.

Fire Origin and Spread

During their initial investigation, TVA Police investigators worked with input from the United States 

Fire Administration, the National Institute of Standards and Technology, and the Nuclear Regulatory 

Commission to perform a fire engineering hazard analysis. According to the TVA Police record of 

investigation, this analysis “assesses the investigation of the fire’s origin and cause, evaluates the performance of fixed fire protection systems, and identifies significant aspects of fire dynamics.” Data 

generated by this analysis would then be used to help identify not only the fire origin and cause, but 

to determine specific hazards that might exist in similar plants.

TVA investigators utilized NIST’s Fire Dynamics Simulator Version 2.9, inputting not only their own 

data but also information provided by USFA, NIST and NRC. The simulator modeled smoke and fire 

development and distribution over a period of time using a three-dimensional computer image to 

provide a second-by-second breakdown of the fire. The results were telling. According to the record 

of investigation, “The model of the WBH (Watts Bar Hydroelectric) Plant after 527 second (8.78 

minutes)...shows a fire plume extending up the cable shaft to the entrance to the ante room, which 

leads up a staircase to the cable spreading room.”

Three-dimensional computer model of WBH fire

FIRE ORIGIN AND SPREAD

During their initial investigation, TVA Police investigators worked with input from the 

United States Fire Administration, the National Institute of Standards and Technology, and 

the Nuclear Regulatory Commission to perform a fire engineering hazard analysis. According

to the TVA Police record of investigation, this analysis “assesses the investigation of the fire’s

origin and cause, evaluates the performance of fixed fire protection systems, and identifies 

significant aspects of fire dynamics.” Data generated by this analysis would then be used to 

help identify not only the fire origin and cause, but to determine specific hazards that might

exist in similar plants.

Three-dimentional computer model of WBH fire

TVA investigators utilized NIST’s Fire Dynamics Simulator Version 2.9, inputting not 

only their own data but also information provided by USFA, NIST and NRC. The simulator 

modeled smoke and fire development and distribution over a period of time using a threedimensional computer image to provide a second-by-second breakdown of the fire. T he 

results were telling. According to the record of investigation, “The model of the WBH [Watts

Bar Hydroelectric] Plant after 527 seconds (8.78 minutes)...shows a fire plume extending up 

the cable shaft to the entrance to the ante room, which leads up a staircase to the cable

spreading room.”
18 U.S. Fire Administration/Technical Report Series

Using information provided in the model, investigators were able to understand not only how the 

fire developed, but also why personnel working in the building had such short notice of the fire’s 

existence. According to the report, smoke and heat from the fire hit the lower levels of the control 

building, “with a good portion of the heat and smoke being transferred out through the upper level 

cable shaft leading to the switchyard.” Instead of smoke and heat spreading into the building, it was 

channeled down the path of least resistance, thereby, diverting any early warning that employees may 

have had. Smoke and heat penetrated the location of the employees only after the fire had built to 

such a fury that the path of greater resistance (the control building itself) could be penetrated.

The information this simulator generated was critical to developing a comprehensive understanding 

of fire development in a hydroelectric plant. It also served to illustrate the dangers associated with 

a fire in such a structure—namely, the rapidity of fire development, and the need for fire detection 

and protection systems.

Lessons Learned

While the firefighting and suppression efforts at Watts Bar were successful, there were several lessons learned. These include the necessity of pre-planning, the importance of local firefighters and 

industrial firefighters conducting training exercises together, the need for adequate training of local 

response personnel in industrial firefighting, the need for effective primary and secondary communications methods, and the importance of compliance with fire codes.

Although plans for the Watts Bar Hydroelectric Plant existed, they were kept in the control building. 

There was no time for employees inside the building to collect the plans prior to exiting the building, so the plans were unreachable and unusable. Local fire departments were not provided with a 

copy of the plans, and so not only were they unfamiliar with the structure, but also did not have a 

visual guide to the design and layout of the building. Fortunately, several firefighters associated with 

the Watts Bar and Sequoyah Nuclear Power Stations and personnel from the hydroelectric plant were 

on-site during fire suppression operations, and were able to provide site and structural information 

verbally. It is critical that facilities relying upon local first responders ensure that these responders 

are provided with all necessary information to respond to and fight a fire at the facility. In addition to 

providing pre-plans to local response agencies, local responders should be given a tour of the facility, 

ideally on an annual or semi-annual basis.

Local first responders should become familiar with their counterparts at the facility, including any 

safety or fire suppression personnel who may work at the site. Not only should responders meet 

during site or facility tours, but they should also periodically drill on response procedures together. 

While the Rhea County emergency manager knew some of the personnel from Watts Bar, local 

responders were not familiar with their colleagues from the Watts Bar Nuclear Power Station fire 

brigade. Training together not only allows for personnel to meet each other, but it enables them to 

become familiar with any differences or similarities in response protocols and equipment that may 

exist between agencies.

In the case of the Watts Bar, an important difference exists between the firefighting training of local 

responders and that of personnel from the Watts Bar Nuclear Power Station. Local responders are 

trained in standard structural firefighting techniques, while personnel from Watts Bar are trained in 

industrial firefighting techniques. While these techniques all focus on fire suppression, they use different methods to achieve the goal. Moreover, fire personnel from TVA have received special training 

in techniques used to extinguish electrical fires, and are familiar with the hazards and limitations 
USFA-TR-147/September 2002 19

associated with fighting such fires. Traditionally, structural firefighters are trained to avoid fighting 

an electrical fire until the power source or the actual fire has been de-energized, or using a suppressant other than water. TVA employees, however, are trained to extinguish a wide variety of electrical 

fires using traditional hose lines. It would be beneficial for local responders to receive training, 

even alongside their industrial counterparts, in the special challenges and techniques of industrial 

firefighting. In this way, all response personnel would be familiar with the same techniques and 

objectives.

Another critical aspect of successful fire suppression is effective communications. Due to the geographical location of the hydroelectric plant, there were several “dead spots”—areas where radios 

cannot receive or send messages. Further complicating matters, the radios of local responders and 

TVA personnel were not compatible. Finally, the signal strength of the radios for the TVA Watts Bar 

Nuclear Power Station Fire Brigade was very weak. Although members of the nuclear power station 

fire brigade were within eyesight of the nuclear power station, personnel could not use their radios 

to reach it in order to keep supervisors there aware of their fireground operations.

On-scene TVA personnel were able to communicate using Nextel phones because of their digital 

walkie-talkie capabilities; however, these phones were only able to receive a signal in an area that 

was roughly ten square feet. Unit officers met face-to-face throughout the incident to communicate 

and make decisions. While effective in this instance, this means of communication is not always 

practical or reliable. If financially feasible, local response units should be provided with a radio from 

the industrial site, thereby ensuring that a means for radio communication exists. Additionally, the 

industrial site should be provided with a radio from the local response agency. These radios could be 

carried in response units, and used exclusively for communication during an incident or drill.

One of the most important lessons learned from this fire is the importance of compliance with the 

Life Safety Code. Although the Watts Bar Hydroelectric plant was grandfathered in due to its age, 

non-compliance with the code could have had fatal results in this fire. As mentioned before, personnel on the powerhouse floor did not know there was a fire burning in the cable shaft. There was also 

no means for warning them, as communication between the control building and powerhouse had 

been cut by to the fire. There are very few means of egress from the powerhouse, and several places 

where an employee could be trapped and seriously injured or killed. Worse, there was no emergency 

lighting, and employees were plunged into total darkness when the power failed. Only the quick 

thinking of a floor supervisor ensured the safe exit of employees. As a result of this fire, TVA has 

realized the importance of the life safety code, and plans to bring all of its hydroelectric plants into 

compliance.