Fire Lessons Learned in
the Nuclear Industry
S. Scott Hinds, PE
March 2011
Acknowledgements
 Bruce
 Dr.
Campbell, PE – HAI
Rowland Felt – Fire Consultant
 Dave
Tomecek, PE - HAI
Outline
 Purpose/Background
 Fermi
Lab Wide Band Fire- 1987
 Rocky
Flats Fire - 1957
 Cerro
Grande Fire (Los Alamos) - 2000
 Welding
Fatality at K-25 - 1997
Outline
 Gaseous
Diffusion Plant Fire - 1956
 Paducah
Chemical Fire - 1962
 Rocky
Flats Fire - 1969
 Conclusions
Purpose and Background
 Provide
brief examples of past DOE/Nuclear related fires
 Provide
an overview of the 1969 fire at the former Rocky
Flats Plant.
 Discuss
 Discuss
the Lessons Learned from these events
how these lessons and events impact our
professional Society
Purpose and Background
presentation is not all encompassing – It does present
an overview of well documented facts
 This
 It
is a fact of life that there are fewer and fewer of us left in
the industry that retain corporate memory of these fires and
in specific - the Rocky Fire of 1969
 We
cannot forget the lessons learned from these events
FERMI Lab Wide Band Fire
 October
3, 1987 – Batavia Illinois.
 Fermi
National Accelerator Laboratory focused on high
energy physics research.
 Fire
started by over-current in a 34 wire ribbon cable and
spread along cable trays to eventually involve 4 particle
detectors.
5
sprinklers activated. Emergency personnel were called to
suppress the fire.
 Over
$1 million in damages.
FERMI Lab Wide Band Fire
FERMI Lab Wide Band Fire
1957 Rocky Flats Fire
 Very
serious plenum fire initiating in a glovebox on the floor
below
 Gloveboxes
constructed of Plexiglas
 Ignited
by spontaneous combustion of Pu metal
 Spread
to Plexiglas
 Extinguished
via hose lines
1957 Rocky Flats Fire
1957 Rocky Flats Fire
1957 Rocky Flats Fire
 Filters
– “Flammable chemical warfare system (CWS) filters”
 Precursor
 Pu
to the HEPA filter
release in the range of 4 to 25 grams
 Fire
suppression measures - post 1957 fire -

Use of glass-fiber filters in lieu of cellulose-asbestos filters

Multiple stage filter plenums
1957 Rocky Flats Fire
Cerro Grande Fire
 May
2000 – Los Alamos, NM
 Largest
forest fire in New Mexico’s history –started as a
controlled burn.
 Burned
7500 acres within Los Alamos National Laboratory’s
boundary. Over 100 minor buildings were destroyed.
 No
buildings containing nuclear material or high explosives
were burned.
closed from May 8 – May 22. Cost of business
interruption estimated at $3 million.
 Laboratory
Cerro Grande Fire
Welding Fatality at K-25
 March
11, 1997 – Oakridge, TN.
 Oakridge
National Laboratory K-25 site.
was being performed in high contamination zone – no
dedicated fire watch was on duty – report indicated the
welder was working alone.
 Work
 Welder
unknowingly ignited his anti-contamination clothing
– fully consumed in flames in < 3mins resulting in fatality.
 Anti-contamination
outfit 100% cotton. Flame retardant
version available, but not made mandatory.
Gaseous Diffusion Plant Fire
Gaseous Diffusion Plant Fire
 November
11, 1956 – Paducah, KY
 Fire
started from a compressor gas seal leak in one of the
smaller buildings in the Paducah Gaseous Diffusion Plant.
 Building
did not have a sprinkler system.
 The
fire ignited the underside of the roof, leading to the
complete destruction of the 70,000 ft2 of roof.
 Despite
limited damage to equipment, total cost was $2.1
million – over $20 million in todays dollars.
 This
incident led to increased sprinkler focused fire
protection systems of AEC plants.
Paducah Chemical Fire
 December
13, 1962 – Paducah, KY
 An
explosion followed by a chemical fire occurred at the
same Paducah Gaseous Diffusion Plant, but in a much
larger building.
 While
the sprinkler system effectively extinguished the fire,
the steam that formed caused most of the 2,341 sprinkler
heads to activate.
 Losses
were reported at $2.9 million. Had the sprinkler
system not been in place, estimated damages >$160
million.
 The
system supported a maximum flow rate of 40,000 gpm
over 23 systems, consuming 2,800,000 gallons of water.
Plutonium Primer – Interesting Facts
 Can
be brittle as glass and malleable as aluminum
 Expands
 Silvery
when it solidifies
machined surface oxidizes and tarnishes in minutes
– spontaneously ignites in air at room
temperatures
 Pyrophoric
 239Pu
– metal –weapons; oxide – MOX reactors
 Ages
from “outside in” – reacting vigorously with its
environment, like O, H₂, and H₂O thus changing its
properties from the surface to the interior.
 Ages
from the “inside out” – continual self damaging decay
fundamentally changes its properties over time.
Plutonium Primer – Fire Facts
 Burning
Plutonium – glows like a charcoal briquette
 Ignition
Temperature – 560 degrees C
 Melting
Temperature – 650 degrees C
 Rate

of Combustion - ~240 grams/hour or 4 grams/minute
Massive metal chunks – hard to ignite - 5.2 BTU/gram
 Surface
area to weight ratios critical to proper handling
Ignition transition area between 0.05 – 0.2 mm thickness
or 7 – 25 cm2/gram specific surface area – higher end 500
degree C – lower end 150-200 degree C
 Pu
 Nuclear
criticality potential high with improper design
 Obviously
– nuclear containment required
Water and Plutonium
 Roland
Felt reported that:

The Rocky Flats fire was the first known fire where water
was used on burning plutonium

It had been hypothesized that a hydrogen explosion could
occur if water was used on burning Pu, none occurred
during the fire

The burned Pu was confined in the fire areas in welldefined piles
“Burning Plutonium”
Basics of Fire Protection – Fuel – Temperature – Oxidizer:
The Fire Triangle
We know from our primer that burning plutonium is missleading - Pu metal simply reacts with oxygen to produce heat
and form a plutonium oxide (the oxidation process)
 Pu
oxide is a nonvolatile substance - converts to a full oxide
if agitated, generally remains a sub-oxide that is still
pyrophoric
 The
greater the surface area to mass ratio, the greater the
chances of oxidation
 Non-alloyed
oxidation
Pu – pure metal - is also more prone to
“Burning Plutonium”
Rocky Flats
Rocky Flats
 Rocky
Flats was a former nuclear weapons production
facility.
 Previously
manufactured various nuclear weapon
components and one of the key facilities within the DOE for
this purpose
 Opened
 6,000
 All
in 1953
acres
facilities were demolished in late 2005
 Largest
D&D project in the nation, several billion dollars. 21
tons of nuclear material, 3 million square feet of structures,
30K liters of Pu solutions, 1500+ gloveboxes, 600,000 cubic
meters of waste.
Rocky Flats
Rocky Flats – Why we are here…
 Site
of two large nuclear fires, one in 1957 and the other in
1969
 1966
brought an end to the dual capability to provide
weapon materials between Hanford and Rocky – Rocky
won the “competition”
 Used
16Kg ingots and no water permitted in the process
 Rocky
capable of very high throughput
 Economic
production
factors were favorable for relative low cost of
Rocky Flats – Pre 2002
Rocky Flats – February 2005
Rocky Flats – September 2005
Rocky Flats – Before the Fire
From
1955 to March 1971:

602 reported fires

374 in Plutonium areas

228 in other areas
 “Although
these figures look high, many of these
were small fires from metal chips or turnings…”
 In
the Plutonium business – fires are expected
Rocky Flats – Before the Fire
1969 Fire - Overview
 May
11, 1969, 2:27 PM (Mother’s Day Sunday)
 The
fire started as a fully involved glovebox fire in Building
776 - one of the main production buildings– moved through
conveyors overhead
 Initial
alarm from a heat detector
 Firefighters
instructed to never use water prior to that fire
1969 Rocky Flats Fire
 Heavy
smoke conditions
 Plexiglas®
biggest smoke factor
 Benelex®
also involved - 1% was combusted – 600 tons
 60-gloves
involved in the initial line
 10
minutes before the fire, Stationary Operating Engineers
and Security had made a walk-thru of the area – no issues
Shielding, Plexiglas and Benelex – WHY
 Due
to the increased throughput, shielding enhancements
were initiated – the plant was experiencing unacceptable
exposures of workers
 Radiation
Protection –

Primary was alpha radiation

60 KeV gamma from 241Am

Neutron from spontaneous fission of 240Pu
 Shielding
–

Alpha – gloves

Gamma – lead sheets

Neutron – plastic/wood composite – Benelex 401 (Masonite Corp)
and Plexiglas (Rohm & Hass)
Shielding, Plexiglas and Benelex
 1967
- Installation of 600 tons of Benelex and Plexiglas
 Workers
could stay longer and “increase their time” in the
work zone
 Cost
– $3.5M neutron shielding effort
 Required
due to unacceptable exposure of the employees
 However,
this increased exposure 40%
 Neutrons
where thermalized to detection range of the
dosimeters – neutrons where slowed down - increased
exposure resulted
 Conveyors
overhead were also a radiation source
Shielding, Plexiglas and Benelex
Solution
 Move
–
shielding into the glovebox
 Develop
Benelex/Plexiglas chests for storage of the
compacted machine turnings
 Plutonium
briquettes were stored in the gloveboxes
and provided with “flower pot” heat detectors
 Briquettes
were pressed Pu chips - briquette is 3inches in diameter and 1-inch thick ~1500 grams
Benelex and Plexiglas – Fire Facts
- 9,900 BTU’s per pound to 11,600 BTU’s
per pound
 Plexiglas
 Ignition
 Some
temperature of 775° F
“fire retardant” methacrylate was used
 Benelex
- Burning characteristics more closely
approach those of the dense hardwoods
 8240
BTU’s per pound
 Ignition
temperature of 795° F
 Prolonged
exposure at 4-hours at 475° F also
causes ignition
Volrath Can Storage
Flower Pot Detector
Rocky Flats Fire Continued
 Over
800,000 gallons of water existed to “fight” the fire
 First
attempts to extinguish the fire were via multiple 50pound CO2 wheeled extinguishers (not successful)
 Water
utilized within 7-minutes via 1 ½ inch lines
 Decision
by the fire captain to use water - was later
commended for this decision
 776
Area not sprinklered or provided with emergency power
 41,000
 Fire
gallons per hour were used to fight the fire
re-ignited due to burning plutonium
Fire Damage
Fire Damage
Rocky Flats Fire
A
total of 33 firefighters and security guards fought the fire
 No
outside firefighting units were called or assisted
 Some
 No
self-contained breathing apparatus was borrowed
action was initiated to contact local authorities or to
establish road blocks outside the plant perimeter
Fire Damage - Roof
Rocky Flats Fire
Why was there no criticality?
in sheep dips – a design feature of these gloveboxes
that resulted in voids below the glovebox base floor
 Water
 Short

bursts of water around the Volrath cans –
Consolidation of the cans - luck
 Fog
streams directed at the top of the glovebox
 Small
blue flames were seen, later found to be magnesium
carriers – scraped off ingots will volatize as blue color
 Pu
“crusting” slowed the oxidation
Rocky Flats Fire
fire spread from Building 776 to 777 – another
production building - within 25-minutes (via the conveyor
line system)
 The
 About
2-hours into the fire the sprinklers on the second floor
were operating
 It
took nearly 6-hours to get the fire under control
was estimated that 100 x 106 BTU of heat was liberated
during the fire – what does that equal???
 It
 About
an average heat release rate of 4884 Kw or a fully
engaged – out of control – burning super Wal-Mart
 About
2000 BTU is a burning couch
Fire Damage
Fire Damage
Rocky Flats Fire – Water versus Pu
 After
the fire it was noted that the Pu Oxide was crusty
instead of powdery
 The
utilization of water had the effect of forming a moist
oxide coating over the burning metal which baked to a rigid
crust
 This
crust prevented the loose oxide from being dispersed
 This
also contributed to the lack of a criticality
Rocky Flats Fire – Root Cause
 No
evidence of arson
 Started
in the North Foundry line of 776
 Self
ignition of a briquette ignited shielding material
 Had
been burning for a long time prior to discovery
 Initiated
inside the glovebox
Rocky Flats Fire – Root Cause
 “With
the installation of the Benelex-Plexiglas storage
container in 1968, the heat detection system was nullified”
 The
type of briquette that self ignited had occurred
previously at Rocky Flats, however the storage
configuration was different (shielding which provided
insulation), thus a self ignited fire was plausible
 About
one-half of the heat released during the fire was from
the Plexiglas glovebox windows
 Less
 The
than 5% was from the Pu
remainder was from the shielding material and gloves
Rocky Flats Fire – Root Cause
 “The
fact that the building structure, including the roof was
not breached by the fire, that most of the ventilation system
continued to operate, and only a part of the final stage of
one set of filters was damaged appear to have been the
controlling factor in limiting the amount of Pu release”
 “Although
the area subjected to fire damage was relatively
small, the damage to equipment and the building due to
contamination was very extensive”
 The
A
conveyor system contributed to the extent of the loss
fire truck hit an electrical pole that took out the ventilation
by mistake – saved the day
Rocky Flats Fire – Damages
 No
serious physical injuries to personnel fighting the fire
 Initial
estimate; $50M in 1969 dollars, ($315M in 2011
dollars)
 Final
 Fist
tally was “only” about $26M ($165M in 2011 dollars)
floor of Building 776/777 grossly contaminated
 Second
floor of Building 776/777 highly contaminated
 An
estimated 1-kg of oxidized Pu was on the floor of the
glovebox of origin (Glovebox 134-39 in building 776)
 Significant
number of other briquettes oxidized within their
containers in multiple gloveboxes
 Total
Pu in Building 776/777 was 3,400-kg
Rocky Flats Fire – Damages
 1,400-kg
was in the area of origin
 Most
damaged Pu was oxidized, some was chemically
damaged due to the loss of inerting
 No
evidence of Pu-Water explosions (due to H₂)
 The
Plexiglas windows in the primary burn area were almost
completely consumed
 In
some of the primary burn area, the Benelex and Plexiglas
shielding was heavily charred
 “The
capability to produce and assemble plutonium pits for
War Reserve weapons was lost for a period of several
months and production of special devices for the weapons
laboratories was interrupted”.
Fire Damage
Pu and Plexiglas
Plutonium Metal
Fire Damage
Fire Damage
Rocky Flats Fire – Conclusions
 Building
776/777, a vital nuclear weapons production facility
did not even meet the minimum AEC fire safety standards
 Plexiglas
 Benelex
 Long
windows most significant contributor
also a contributor (only 1% burned)
interconnected conveyor system – highway for fire
 Recycling
 Storage
of turnings, chips and skull material
of Pu briquettes without lids
 If
there had not been the Benelex-Plexiglas storage
container, the fire would not have ignited the windows
 The
Benelex-Plexiglas container also impaired the use of
storage container heat detectors
Volrath Can Storage
Rocky Flats Fire – Conclusions
 The
Benelex and Plexiglas shielding also made fire fighting
and clean-up efforts difficult
 No
loss time injuries
firefighters who fought the fire were hero’s and they
clearly prevented a much more serious and catastrophic fire
 The
 Combustible
 The
loading was the primary contributor
lack of automatic sprinklers, sufficient detection and fire
barriers were also a major contributors
Rocky Flats Fire – Lessons Learned
 Facility
wide automatic sprinkler protection
 Non-combustible
containers with tight fitting lids for the
storage of all forms of Pu
 Eliminate
unnecessary storage of combustibles within
gloveboxes - Combustible loading was the primary
contributor
 Glovebox
overheat detection system was upgraded and
fixed detectors which monitor air temperatures were added
 Quicker
processing of pyrophoric forms of Pu having a large
surface to mass ratio such as turnings, slag, to PuO2
Rocky Flats Fire – Lessons Learned
 Production
areas eliminated Plexiglas and Benelex
shielding
 The
use of plastics as glovebox structural components were
eliminated
 The
use of gloveboxes and conveyor lines for long-term
storage of Pu was eliminated, storage accomplished via
storage vaults which were nitrogen inerted
 Fire
stops were provided for gloveboxes and conveyor lines.
 Dampers
were automatic
Rocky Flats Fire – Lessons Learned

Ventilation systems for Pu processing lines were
changed to supply & exhaust air from GB’s and
conveyor lines
o

At the time of the fire, air was drawn into the GB’s from
the room and exhausted through the conveyor system.
Using the conveyor system contributed to the fire
spread
Areas with pyrophoric Pu were N2 inerted
o
It was found that O2 of less than 5% inhibits the ignition
of Pu (plus all other combustibles)
Rocky Flats Fire – Lessons Learned
 All
room air exhaust plenums were equipped with a cooling
chamber and two stages of HEPA filters
 Cooling
is achieved by automatic water sprays which
provide an amount of water calculated to reduce 1000º F
inlet air to approximately 200º F, system activated by 190º F
heat detectors
 All
glovebox air exhaust plenums and inert plenums were
provided with 4-stages of HEPA in lieu of 2-stages
Glovebox Exhaust Plenums
Rocky Flats Fire – Lessons Learned
 Manually
operated deluge systems were provided for the
first stage of HEPA filters
 All
exhaust filter plenums were designed to prevent direct
impingement on the face of the HEPA filters
 Accomplished

via baffles or directional air changes
Heat detectors were provided upstream of filters
Directional Air Change Baffle
Rocky Flats Fire – Lessons Learned
 Fire

rated walls and doors were provided to limit fire spread
Including upgrading of exterior walls and roofs
 Rooms
were subdivided to limit the spread of fire
 Two
2500 gpm fire pumps and Two 500,000 gallon suction
tanks
 New
fire alarm system
 Emergency
 The
generators – Lighting - Ventilation
lack of automatic sprinklers, sufficient detection and fire
barriers were also a major contributors
Rocky Flats Fire – Lessons Learned
 Sprinklers,
sprinklers, sprinklers…
 Combustible
loading
 Fixed
suppression systems
 Fixed
detection systems
 Fire
 An
separations
adequately staffed on-site professional fire department is
critical
Rocky Flats Fire – Lessons Learned
 “While
Rocky Flats does have fire protection experts and
they provide advice to line management when called upon,
there is no one centralized safety organization with
appropriate responsibility to assure that overall safety
evaluations are performed.”
Final Look