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Director, Office of Nuclear and
Facility Safety
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U.S. Department of
Energy
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Washington, DC
20585
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DOE/NS-0013
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Issue No. 93-01
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February
1993
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FIRE, EXPLOSION, AND HIGH-PRESSURE HAZARDS
ASSOCIATED WITH WASTE DRUMS AND CONTAINERS
Contents
NOTICE SUMMARY
This notice is a lessons-learned document on safe storage
and handling of waste containers and drums, relating
specifically to the handling, storing, venting, and opening
of containers that may be pressurized or may contain
flammable vapors. This notice also provides generic
information about proper storage conditions and the material
condition of containers and drums.
APPLICABILITY
The information in this notice applies to all Department
of Energy (DOE) facilities that store volatile chemicals and
hazardous wastes in containers (e.g., drums). The Office of
Nuclear Safety advises operators of applicable DOE
facilities to understand the safety hazards related to the
storage of hazardous materials in containers and the factors
that make containers susceptible to deformation and fire or
explosion. This notice requires no specific action or
response.
EVENTS SUMMARY
Records show that at least eight incidents of fire,
explosion, and drum over pressurization occurred at DOE
facilities from 1970 through 1985. (Ref. 1). An ignition
source or a reaction between incompatible materials
triggered each incident; the hazardous waste constituents of
the mixed radioactive waste served as fuel. Of particular
interest is the explosion of a 55-gallon drum in a truck at
Argonne National Laboratory (ANL)-East on December 2, 1976.
Apparently two solvents, xylene and pentane, diffused
through a polyvinylchloride (PVC) pouch and collected in the
drum's void space. The ignition source was an electrical
discharge, possibly either static electricity from the
plastic bags containing the solid radioactive waste or
electricity generated by piezoelectric crystals from a
discarded ultrasonic cleaner. Fig. 1 shows the hole in the
metal roof of the truck and the mangled reinforcing beam in
the roof structure. The drum lid was found on top of the
truck. Fortunately, no one was near the truck at the time of
the explosion, and there was no spread of contamination.
Several recent incidents at DOE facilities involved drum
overpressurization or rupture. During a weekly inspection of
hazardous waste drums, personnel at the Rocky Flats Solid
Waste Treatment Facility discovered a deformed liquid waste
drum. (Ref. 2). The 55-gallon waste container was made of a
translucent plastic without vents and held approximately 15
gallons of hazardous chemicals with vapor pressures
sensitive to temperature changes. Rising temperatures
volatilized the chemical wastes and overpressurized the
container. (The normal ambient air temperature in the
canister storage facility exceeds 100° F.)
Five incidents of swelling waste containers have occurred
at the Paducah Gaseous Diffusion Plant (PGDP). (Ref. 3)
Facility personnel identified seven waste streams, several
containing organic materials, that have the potential to
generate gases when stored. The causes of gas generation
include incompatibility of the container with the wastes,
bacterial growth in wastes, and storage of wastes with low
boiling points in sealed containers. Gases generated within
the containers includes hydrogen and methane which also pose
a fire or explosion hazard.
FIGURE 1 DAMAGE INSIDE A TRUCK AT ANL-EAST is not
available in this document. If you would like to obtain a
copy of it, you may contact the Nuclear Safety Information
Center at (301) 903-0449 or by writing to NSIC, U.S.
Department of Energy, EH-15/Suite 100, CXXI/3, Washington,
DC 20585.
At the Fernald Environmental Management Project, a
55-gallon drum containing waste materials violently ruptured
when it was moved with a forklift. (Ref. 4). Approximately
three months, later a drum containing similar material
violently ruptured while being moved. (Ref. 4). Water in the
drums had reacted with uranium, and the resultant hydrolysis
reaction produced hydrogen, which led to the explosions. An
inspection discovered four additional bulging waste drums in
a storage building at Fernald. (Ref. 5). Unspecified
corrective actions were taken to relieve pressure in
approximately 80 drums. Chemical reaction of the wastes
produced hydrogen and overpressurized the drums. (Ref. 5).
Another event at Fernald involved a 55-gallon drum inside
an 85-gallon overpack drum. (Ref. 6). The lid on the 85-
gallon drum blew off when an operator removed the bolt on
its lid-locking ring. The operator tripped over a cart and
fell but was not hurt. The lid on the 85-gallon drum was
rusted. The lid of the 55-gallon drum had rusty holes.
Bulges around one hole indicated that the 55- gallon drum
may have ruptured prior to the larger drum's lid blowing
off. Carbon dioxide buildup in the drum caused the
overpressure. The drum contained sludge from the
Biodenitrification Sludge Lagoon.
During an inspection of containers before offsite
shipment, personnel at the Hanford Nonradioactive Dangerous
Waste Storage Facility noted a slightly bulging drum. (Ref.
7). During a follow-up inspection, personnel found that the
drum showed signs of additional bulging. Facility personnel
vented the drum to reduce the pressure. During a subsequent
inspection, the drum was found to be pressurized and was
again vented. The report of the incident does not cite the
specific cause of the vapor generation.
Other incidents involving bulging containers at Hanford
have occurred in the 200 West Area. For example, personnel
recently discovered a bulging 55-gallon drum, and the
emergency response team attempted to drill through the drum
with no success. (Ref. 8). The response team moved the drum
into a building and opened it. Approximately nine additional
drums were moved into the building. The lids on these drums
will be removed in the near future. The report of this
incident also does not cite the specific cause of vapor
generation.
At ANL-West, a container ruptured because incompatible
wastes were mixed. The Analytical Laboratory mixed 2
quarters of liquid acidic waste into a 5-gallon plastic
container holding 4 gallons of acidic wastes. (Ref. 9). A
technician immediately placed the lid on the container. The
oxidation reaction between dilute nitric acid and the
existing waste caused a gas buildup that ruptures the
container.
SIGNIFICANCE OF EVENTS
The safe storage and handling of hazardous materials
require good management of process chemistry, waste, and
safety and health reviews, together with excellent design,
fabrication, inspection, and maintenance of containers.
These elements help prevent equipment failures or human
errors that might lead to fire, explosion, or release of
contaminated materials. In addition, workers need to be
aware of the hazards associated with the storing, opening,
and handling of waste containers. DOE facilities should
develop and enforce clear and consistent guidelines and
procedures for handling and storing hazardous wastes in
containers.
Regardless of how well a waste disposal and handling
facility is engineered, constructed, and operated,
preparedness for abnormal events (e.g., the discovery of a
pressurized drum) can make the difference between a minor
incident with limited and controlled consequences and a
major incident with the potential loss of life and
significant equipment damage. Facilities that handle waste
drums and containers must undertake an emergency planning
that is commensurate with the risks to their employees and
to the surrounding communities. They should develop
procedures to address the moving, venting, and repackaging
of pressurized and/or bulging drums. DOE facilities should
consider use of nonsparking tools or remote venting devices
to help prevent ignition of flammable vapors. Fig. 2 shows
an examples of a remote venting device. After venting the
drum facility personnel should store or repackage the waste
in a manner that precludes repressurization of the drum.
FIGURE 2 REMOTE VENTING DEVICE. PORTABLE DRUM PUNCH
(REMOTELY OPERATED) is not available in this document. If
you would like to obtain a copy of it, you may contact the
Nuclear Safety Information Center at (301) 903-0449 or by
writing to NSIC, U.S. Department of Energy, EH-15/Suite 100,
CXXI/3, Washington, DC 20585.
POTENTIAL CAUSES
There are many potential causes of drum
overpressurization. These include
- generation of gases due to corrosion of metals such
as uranium, zinc, magnesium, or zirconium, radiolysis of
organic materials, chemical reactions involving
incompatible materials, or decomposition of wastes by
anaerobic bacteria:
- generation of vapors due to storage of volatile
materials at unsafe temperatures; and
- ignition of pyrophoric materials or flammable vapors
or liquids.
A significant source of hydrogen generation is corrosion
of uranium metal. (Ref. 10). The rate of hydrogen generation
is strongly dependent on the form of the metal and on the
extent to which water remains in contact with the metal
during storage. The hydrogen generation rate can easily
surpass the venting capability of a container, resulting in
over-pressurization. Ignition of the accumulated hydrogen
can cause an explosion; contact of uranium metal with the
drum wall can provide the spark ignition source.
Radiolysis of organic materials produces hydrogen, carbon
dioxide, carbon monoxide, and light hydrocarbon gases. (Ref.
11). Some sites dispose of wastes in PVC or polyethylene
bags. The bags are tightly sealed by twisting the bag top
and taping the twisted bag top. A high-density polyethylene
drum liner holds many sealed bags. The bags are loaded into
liner, and then the liners are loaded into vented 55-gallon
steel drums. Radiolysis causes bag degradation, which can
produce enough hydrogen to exceed the lower flammability
limit of a gas-air mixture in the bags or liner. The drum
vent may provide protection against a buildup of hydrogen in
the liner; however, it provides no protection against the
formation of a flammable hydrogen-air mixture in an
individual PVC or polyethylene bag. (Ref. 12). PVC which
absorbs significant water, poses additional problems for
materials that react with water.
Both storing and mixing reactive materials require
special precautions. The principal concern is chemical
reaction of incompatible materials. These reactions can
cause exothermic heat generation, evolution of gases, and an
associated rapid pressure increase in the container.
Important considerations with reactive materials include
control of contaminants and selecting the proper container
materials and construction to avoid energetic reactions. As
a result of chemical reactions, a sealed drum's atmosphere
can become depleted of oxygen. Air, entering a drum when it
is opened, can combine rapidly with reactive metals and
hydrides. Such a reaction can be very energetic if the
reactive metals are coated with cutting oils.
Anaerobic bacteria can cause decomposition of wastes
stored in containers, which can produce methane and carbon
dioxide. Facility personnel should consider methods to
prevent or retard the growth of anaerobic bacteria in
container should be considered.
Facilities must not store containers holding volatile
materials in areas subject to high sections on emergency
isolation of leaks and breaks and emergency transfer of
materials.
A rigorous evaluation of potential ignition sources is an
important consideration in preventing fires and explosions.
A Recommended Practice of the American Petroleum Institute
gives basic information on ignition sources and combustion
processes, and indicates sources of more detailed
information. (Ref. 16).
The storage of flammable wastes in steel or plastic 55-
gallon drums presents a significant fire potential. A drum
fire at an Imperial Chemical facility in England destroyed
450 drums (90 tons of material) in 9 minutes. (Ref. 17). The
drums contained nitrocellulose dissolved in isopropanol.
They burned in an isopropanol fire that began when a drum
fell off a forklift. The falling drum hit another drum, thus
igniting a small amount of nitrocellulose spilled on the
outside of the falling drum. The fire spread to a drum with
a small leak of isopropanol and then to the entire stack of
drums. Witnesses reported drums going up into the air. One
employee was killed, several were injured. The surrounding
buildings, including the fire station, were destroyed.
Although not directly related to waste storage, this example
illustrates how drum stocks can grow uncontrolled, creating
severe, significant, and unintended consequences. The
specific lessons learned from this event relate to the
siting of drum storage and the control of the drum stocks.
Sites for drum storage should be chosen with care rather
than simply on a basis of available land or warehouses. The
number of drums stored in a particular location can exceed
safe limits if proper procedures are not in place. Fires
involving flammable liquids in steel drums are characterized
by explosive, catastrophic failures of the drums, similar to
a boiling liquid expanding vapor explosion (BLEVE) of a
pressure vessel. (Ref. 18). Plastic drums usually do not
exhibit explosive failure, but fires do breach the drums
rapidly and in multiples. Each design for fire protection of
drums stored in warehouses should be evaluated. General
criteria include
- simplicity of the design,
- reliability of the components,
- complete testing of the design, and
- conformance of the design to applicable design
standards and building codes.
REFERENCES
1. M. Silva, "An Assessment of the Flammability and
Explosion Potential of Defense Transuranic Waste," Nuclear
Safety, 33-3, July-September 1992.
2. DOE Occurrence Report RFO--EGGR-SOLIDWST-1992- 0039,
"#1232 RCRA Notification Violation," August 12, 1992.
3. DOE Occurrence Report ORO--MMES-PGDPCHMWST-1992-006,
"Multiple Incidents of Waste Containers Swelling due to
Overpressurization from Gas Generation," July 24, 1992.
4. DOE Occurrence Report ORO--WMCO-FMPC-1991-004,
"Pressure Buildup and Release from a 55-Gallon Drum of MTC
219 Material," January 15, 1991.
5. DOE Occurrence Report ORO--WMCO-FMPC-1991-005,
"Building Mixed Waste Drum," January 15, 1991.
6. DOE Occurrence Report ORO--WMCO-FMPC-1992-0089,
"Pressurized Drum Incident in Plant 8," September 9, 1992.
7. DOE Occurrence Report RL--WHC-SOLIDWASTE-1991-1009,
"Potential Drum Integrity Problems," November 21, 1991.
8. DOE Occurrence Report RE--WHC-WHC200EM-1992-0051,
"55-Gallon Drum of Waste Is Bulging at Both Ends," August
28, 1992.
9. DOE Occurrence Report CH-AA-ANLW-AL-1990-0002,
"Overpressurization of a Hazardous Waste Accumulation
Container," April 1, 1992.
10. Personal correspondence, M.J. Galper to H.F.
Daugherty, July 17, 1992, Westinghouse Materials Company of
Ohio.
11. John P. Ryan, Radiogenic Gas Accumulation in TRU
Waste Storage Drums, DP-1604, Savannah River Laboratory,
Aiken, S.C., January 1982.
12. K.L. Dykes and M.L. Meyer, TRU Durm Explosion Tests
(U), WSRC-TR-90-165, Savannah River Site, Aiken, S.C., June
1991.
13. Operating Experience Weekly Summary July 31-August 6,
1992, Summary 92-15, Office of Nuclear Safety, Department of
Energy, Washington, D.C., August 1992.
14. Guidelines for Safe Storage and Handling of High
Toxic Hazard Materials, Center for Chemical Process Safety,
American Institute of Chemical Engineers, New York, 1988.
15. Guidelines for Vapor Release Mitigation, Center for
Chemical Process Safety, American Institute of Chemical
Engineers, New York, 1988.
16. Fire Protection in Refineries, American Petroleum
Institute, Recommended Practice 2001, Washington, D.C.,
1984.
17. M.A. Delichatsios, "Exposure of Steel Drums to an
External Spill Fire," Plant/Operations Progress, Volume 4,
No. 3, American Institute of Chemical Engineers, New York,
July 1985.
18. R.E. Capizzani, "An Overview of Flammable Liquid Drum
Storage and Protection," Plant/Operations Progress, Volume
4, No. 3, American Institute of Chemical Engineers, New
York, July 1985.
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