Lessons Learned: HQ-EH-2004-01
Title: Degradation and
Failure of Stored Radiological Material Containers
The failure of an irradiated test specimen canister
on December 3, 2003 and the breaching of a plutonium-238
package and resulting in worker uptake exposures
on August 5, 2003 demonstrate that long-term storage
of radioactive material containers and packages
continue to pose hazards. Corrosion and other
degradation of radioactive material packages and
their contents, in combination with the buildup
of pressurized flammable gases from radiolysis
and decomposition, can create the potential for
accidents unless such conditions are considered
in design and maintenance, and for the actual
storage lives of the packages.
Learned Statement: Recent events
demonstrate that long-term storage of radioactive
material containers and packages continue to pose
hazards. Corrosion and other degradation of radioactive
material packages and their contents, in combination
with the buildup of pressurized flammable gases from
radiolysis and decomposition, can create the potential
for accidents unless such conditions are considered
in design and maintenance, and for the actual storage
lives of the packages.
On December 3, 2003, at the
Naval Reactors Facility on the Idaho National Engineering
and Environmental Laboratory, a canister containing
an irradiated non-fuel test specimen failed catastrophically
while stored in a water pool. The failure made a large
noise, dislodged the stainless steel canister (made
from 4-inch diameter schedule 40 pipe, 18 inches long),
ruptured its brass cap, and projected part of the
cap 10 feet away underwater. No injuries or other
damage occurred and there was no measurable release
of radioactivity to the environment.
cap screwed onto the canister, with two nitrile rubber
o-rings providing a watertight seal. Investigators
found evidence of water leakage inside the canister.
Their preliminary conclusion is that during the 14
years the canister was stored in the water pool, the
nitrile rubber seals degraded from exposure to high-flux
gamma radiation emitted from the test specimen. Water
leaked into the canister and the canister subsequently
resealed tightly as a result of the brass cap's corrosion.
Radiolysis caused the captured water to break down
into hydrogen and oxygen gas, pressurizing the canister.
(Decomposition of the nitrile rubber could also generate
flammable gases.) The investigators concluded that
the hydrogen detonated and caused the failure. Although
the ignition source is not now clear, it could have
been thermal energy from the specimen, reactions from
radicals produced by the radiolysis, sparking from
interaction of metallic components, or static electricity
recent case involving hazards from degradation of
a radioactive materials container occurred on August
5, 2003, at Los Alamos National Laboratory (LANL)
Technical Area 55. A package containing residues from
plutonium-238 operations breached while being handled
by two workers performing a pre-inventory check. The
pressurized release of materials from the package
gave the workers uptake doses of two or three rems
CEDE. Slightly different release conditions could
have increased the doses by orders of magnitude.
package had been in storage since 1996. A subsequent
Type B investigation concluded that chemical, radiolytic,
and thermal decomposition of the package and its contents
produced significant corrosion and gas in the package.
The corrosion caused "breathable" seams in the package
to seal and resulted in the buildup of gas pressure.
Handling the package dislodged corrosion in the package
and pressurized contaminated gases vented into the
In DOE, the causes and potential
consequences from aging and degradation of radiological
material packages have been well know since at least
the early 1990's. Then, many packaging configurations
intended for only temporary storage became subjected
to much longer storage periods. The increased frequencies
and mechanisms of radioactive material packaging failures
were analyzed and disseminated in initiatives such
as the Plutonium and Highly Enriched Uranium Vulnerability
Studies. A considerable effort was made to process
or repackage the stored materials. Today, however,
there are still radioactive material packages poorly
designed for extended storage, as evidenced by recent
of the Type B accident for the LANL occurrence noted
that corrosion and degradation of similar plutonium-238
residue packages had caused multiple near miss events
since 1994. In the prologue to this report, the Manager
of the Los Alamos Site Office stressed that the accident
could have been avoided if only the lessons learned
from the near misses had been addressed.
design, evaluation, and maintenance of radioactive
material packages must address aging and degradation
of their contents and packaging components.
- The design, evaluation,
and maintenance of radioactive material packages
should consider potential scenarios involving combinations
of component failures, particularly aging mechanisms
that open and seal containment and vents in combination
with those that generate flammable and pressurized
- The packaging of radioactive
materials in long-term storage should be checked
to see if they have design specifications compatible
with currently planned storage lives and conditions.
- If such design specifications
are not met, or do not exist, then the packaging
needs to be evaluated for currently planned storage
lives and conditions.
- Near misses from packaging
failures need be recognized and addressed to prevent
- When dealing with radioactive
material packages that have not been designed to
current standards (i.e., legacy materials), always
assume that the package is unsafe until it is proven
safe or repackaged to current standards.
Dan Guzy, EH-3
Jim Mangeno, NA-1
Guzy, (301) 903-2428
of Authorized Derivative Classifier:
of Reviewing Official:
Blue / Information
Container, canister, package, aging, degradation,
corrosion, storage, radiolysis, hydrogen.
Two Employees Found Contaminated After CAM Alarmed
During Work in TA-55, Building 4, Room 201B
B Accident Investigation of the August 5, 2003 Plutonium-238
Multiple Uptake Event at the Plutonium Facility, Los
Alamos National Laboratory, New Mexico, December,
Plutonium Working Group Report on Environmental, Safety
and Health Vulnerabilities Associated with the Department's
Plutonium Storage, November 1994.
Highly Enriched Uranium Working Group Report on Environmental,
Safety and Health Vulnerabilities Associated with
the Department's Storage of Highly Enriched Uranium,
in this report is accurate to the best of our knowledge.
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/ Work Categories:
Develop / Implement Controls
Fire and Explosion
Radiological Exposure and Contamination