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OCR for page 1
Executive Summary
There are 2,253 tons of chemical agents in the
661,559 individual munitions and 108 ton containers
stored at Anniston Army Depot in Anniston, Alabama.
This is almost 10 percent of the current 23,416 tons of
mustard and nerve agents in the U.S. chemical weap-
ons stockpile. The Anniston Chemical Agent Disposal
Facility (ANCDF) has been constructed and is being
readied for operation in 2003 with the mission of de-
stroying the aging munitions and bulk containers of
agent in this stockpile safely and expeditiously. The
quantitative risk assessment (QRA) performed for
Anniston indicates that the risk to the public is domi-
nated by accidents that could arise from the storage of
M55 rockets filled with GB nerve agent. The QRA sug-
gests that as the M55 rockets are safely destroyed dur-
ing the first disposal campaign, the risk to the public
decreases.
During disposal of GB M55 rockets at Tooele,
Utah, about 5,000 rockets could not be drained be-
cause the GB contents had gelled. These gelled rock-
ets were processed at a much slower rate that required
modification and extension of the disposal process.
About 20 percent (at least 8,706) of the Anniston GB
M55 rockets are now estimated to be gelled. The
Army has developed modified plans for their safe and
expeditious disposal. This report reviews those plans.
The discussions in this report focus on technical con-
siderations and related issues in going from a gelled
GB M55 rocket processing rate of 1.0 or 1.6 rockets
per hour to 9.2 rockets per hour, which would work
out to 6.4 rockets per hour on the basis of an expected
70 percent availability for the deactivation furnace
1
system (DFS). Other rates that are reported are given
to reflect the variability of operational experience to
date in the processing of both gelled and ungelled
(drained) GB M55 rockets. Drained rockets are de-
fined as rockets from which at least 95 percent of the
agent has been removed.
The M55 Committee's formal findings and recom-
mendations can been found in Chapter 5. Major points
from the findings and recommendations have been in-
corporated into the narrative text of this Executive Sum-
mary, along with abbreviated background material.
THE BASELINEINCINERATION SYSTEM
As of July 2002, about 26 percent (8,082 tons) of
the original 31,495-ton stockpile had already been de-
stroyed in baseline incineration system facilities at
Johnston Island in the Pacific Ocean and at Tooele,
Utah. ANCDF, with minor changes, is patterned after
those two facilities, the Johnston Atoll Chemical
Agent Disposal System (JACADS) and the Tooele
Chemical Agent Disposal Facility (TOCDF). In
baseline facilities such as these, munitions are trans-
ported from the depot storage area to a receiving dock
at the disposal facility, unloaded, and conveyed into
explosive containment rooms, where they are disas-
sembled by machines (or, in the case of rockets,
sheared into sections) and drained of agent. The agent
is disposed of in a liquid incinerator (LIC) furnace.
The metal shell casings or ton container sections are
decontaminated in a metal parts furnace (MPF). The
energetics burster charges, fuzes, and propellants-
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2
are destroyed in a DFS, which is a rotating kiln. There
was also a fourth furnace at JACADS and TOCDF,
the dunnage incinerator (DUN), which was designed
to destroy various nonmunition wastes such as ship-
ping pallets. However, when ways were found to ship
these wastes off-site or to destroy them in the MPF,
the DUN was no longer required, so none has been
included in the ANCDF design.
Each of the three furnaces in the ANCDF baseline
design has its own pollution abatement system (PAS).
In a PAS, the hot flue gas, containing some acidic prod-
ucts from agent combustion, is treated with caustic to
form brine, filtered, and discharged through a stack.
The brine can be either shipped off-site to a permitted
disposal facility or treated in a brine reduction area
(BRA). Again, because the Army has found that off-
site disposal can be done safely and economically, the
BRA at Anniston probably will not be used. A third
difference from JACADS and TOCDF is that the ex-
haust gas that leaves a PAS at ANCDF is then passed
through a filter system (high-efficiency particulate air
[HEPA] and activated carbon) before being discharged
through the stack. These HEPA and carbon filters,
known as the PAS filter system (PFS), provide a sec-
ond line of defense to ensure that agent, metals, and
other potentially harmful products are not released to
the environment.
M55 ROCKETS
Among the munitions stored at Anniston there are
42,738 GB M55 rockets and 24 GB M56 rocket war-
heads containing 10.7 lb of GB agent each. Another
35,636 rockets and 26 warheads contain 10 lb of VX
nerve agent each. An explosive burster charge activated
by an impact fuze disperses the agent when the rocket
hits a target. M55 rockets are powered by a stabilized
double-base propellant, nitrocellulose and nitroglyc-
erin, which ignites when the rocket is fired. The rocket
has an aerodynamically shaped, finned aluminum body
that is contained and shipped ready to use in a fiber-
glass firing tube. Altogether, the combustibles in each
rocket agent, burster charge, fuze components, pro-
pellant, and epoxy resin in the fiberglass shipping
tube weigh about 40 lb.
GB M55 rockets carry the highest risk potential of
any chemical stockpile munitions. This is in part be-
cause GB is more volatile than VX and can disperse
farther in an accidental release, and in part because the
ASSESSMENT OF PROCESSING GELLED GB M55 ROCKETS AT ANNISTON
rockets, which are arranged in compact arrays of 15
per pallet, are stored in igloos, as are most other items
in the chemical stockpile. Thus, if one rocket were to
ignite, it might ignite the others. While this is also true
for rockets containing VX, which is more toxic than
GB. VX is not as volatile and will not disperse as
widely as GB. The net effect of this in terms of risk
management is the scheduling of GB M55 rockets to
be processed first. This is how the processing was man-
aged for JACADS and TOCDF and how it is planned
for ANCDF.
Storage Stability of GB M55 Rockets
Concerns about the storage stability of GB-filled
rockets led Congress in 1985 to legislate destruction of
the stockpile. Among the concerns was the fact that the
propellants degrade slowly, possibly leading to auto-
ignition. A stabilizer compound, 2-nitrodiphenylamine,
had been added to the propellant during manufacture to
scavenge products of the degradation reaction. How-
ever, once stabilizer concentrations fall below a critical
level, there is some risk of a runaway reaction that
could cause the propellant to autoignite. Enough stabi-
lizer was therefore added to protect the rockets from
autoignition over what was originally thought to be a
safe storage period. The stockpile has been monitored
in the interim, and rocket sampling studies show that
the expected depletion of stabilizer continues.
Another concern was that GB munitions were found
to leak at about five times the rate of other munitions
(about 0.25 percent versus 0.05 percent). Leaking mu-
nitions, including rockets, generally have been over-
packed in tightly sealed steel containers. Overpacking
usually controls leaking but heightens concerns about
autoignition because the container acts as a barrier to
heat transfer from within the rocket to the surrounding
air in the storage igloo. Also, if GB leaks into the pro-
pellant, there is a further possibility of accelerated pro-
pellant degradation.
Since 1985, a number of scientific evaluations have
assessed the likelihood of autoignition over time, as
the stockpile ages. All concluded that completion of
stockpile destruction, currently programmed to meet
the 2012 extended deadline of the international
Chemical Weapons Convention treaty, will occur long
before the risk of autoignition is appreciable, even for
overpacked, leaking rockets. The frequency estimate
for an M55 autoignition event in the latest study is
site specific; currently, it is approximately 3 x 10-5
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EXECUTIVE SUMMARY
per year for the Anniston site. This is much lower
(by a factor of 60) than the estimated 2 x 10-3 per year
frequency (an average of once in 500 years) of igni-
tion from a lightning strike on a storage igloo. Ac-
cording to the stability model used by the Army, the
autoignition probability will increase gradually but
will stay below the lightning strike probability mea-
sure until 2020. The M55 Committee has broadly re-
viewed the rationale, structure, and results of this
study and concluded they are sound. A more detailed
review will be presented in a forthcoming National
Research Council report on the status of stockpile
degradation.
Gelled GB M55 Rockets
GB and VX M55 rockets are normally processed by
first draining at least 95 percent of the agent from a
rocket, shearing it into sections in a rocket shear ma-
chine (RSM) in the explosion containment room (ECR)
and processing the sections in the DFS kiln system.
The drained agent (less a 5 percent or smaller heel of
agent that usually remains in the rocket) is fed to the
LIC. The MPF is not used in processing rockets. At
JACADS, all the GB and VX rockets contained
ungelled agent and were drained and processed in this
manner, and most of the GB rockets processed at
TOCDF were also processed this way. However, three
particular lots in the Tooele stockpile totaling 5,287
GB rockets (of the 28,945 total) contained gelled agent
that would not drain. Gelling is apparently the result of
GB degradation, which increases acidity, leading to a
reaction with the aluminum tank material. It is believed
that this produces an aluminum phosphonate species
that can, over time, link GB derivatives and cause them
to gel. Most of the originally more acidic agent lots
were restabilized with diisopropylcarbodiimide
(DICDI), and some of the restabilized lots are those
that are gelled. Most other remaining lots contain an-
other agent stabilizer, tributylamine, and no gelling ef-
fects were detected when that stabilizer had been used.
iThis is the median site-specific annual autoignition probability
for overpacked rockets at Anniston and is equivalent to about one
chance in 33,000 per year. The median site-specific annual
autoignition probability for nonoverpacked (undetected) leaking
rockets at Anniston is approximately 1.4 x 1 o-6 (about one chance
in 700,000 per year). The lower frequency estimate for
nonoverpacked leaking rockets is due to their lower peak heat gen-
eration and slightly higher heat losses compared with overpacked
rockets.
3
At Anniston, the current estimate is that 8,706 of the
42,738 GB M55 rockets are probably gelled, based on
munition lot numbers that have been associated with
gelled agent. Very few gelled rockets are expected to
be encountered at the other two sites using the baseline
incineration system for disposal (Pine Bluff, Arkansas,
and Umatilla, Oregon). For this reason, any gelled
rockets at those two sites can be processed at the lim-
ited rate of 1.6 rockets per hour used at TOCDF with-
out causing serious delays. The committee suggests the
Army proceed at the Pine Bluff and Umatilla sites un-
der existing permit applications, which (as in the case
of TOCDF) provide for a processing rate in the DFS
based on agent loadings from processing rockets with
no more than a 5 percent agent heel.
Lessons Learned at JACADS and TOCDF
in Rocket Processing Operations
The very first agent disposal operation undertaken
in the Chemical Stockpile Disposal Program (CSDP)
was the processing of drained (ungelled) GB M55 rock-
ets at JACADS starting in 1989. The planned goal was
32 rockets per hour. A "best shift" rate achieved for
one day was 27 rockets per hour during the first opera-
tional verification test (OVT 1) campaign. The best
operation over an extended period (the "full rate") was
15.3 rockets per hour. The processing at JACADS rep-
resented first-time experience with an (at that time)
untried, extremely complex process system. Much of
the processing rate shortfall can be attributed to the
learning that was necessary for the operations team,
notwithstanding the months of training that had been
invested before start-up. After some modifications to
equipment and procedures as a result of problems en-
countered, the VX rocket operation (OVT 2) went more
smoothly. The full rate was 20.6 per hour, although 32
rockets were processed per hour over one full 10-hour
shift.
TOCDF benefited significantly from the JACADS
experience, and operations there on ungelled rockets
went well. However, the processing of gelled rockets
caused serious delays. These rockets were processed in
a substantially different way than the ungelled ones. In
the ECR, gelled rockets bypassed the drain station and
were sheared in the RSM into segments containing
large amounts of agent as well as fiberglass and ener-
getics. This mix of rocket components and agent was
fed to the DFS kiln. Neither the LIC nor the MPF was
used to process rockets in this instance. The total com-
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4
bustible content per rocket delivered to the DFS kiln
thus went from roughly 30 lb to 40.4 lb. TOCDF man-
agement obtained approval from the Utah regulatory
authorities for 1.6 gelled rockets to be processed
through the DFS kiln each hour. This contrasts with the
permit rate of 32 drained, ungelled rockets per hour.
The rate for gelled rockets was reduced so that the same
amount of agent would be destroyed per hour in the
DFS as would have been the case when drained rockets
with a 5 percent heel were processed. When downtime
is taken into account, the actual average rate for pro-
cessing gelled rockets over the entire campaign was
approximately 0.6 rockets per hour.
To speed destruction of the entire inventory of GB
munitions at the Deseret Chemical Depot at Tooele,
TOCDF management developed the concept of "co-
processing." While gelled rockets were being pro-
cessed through the DFS, GB projectiles, reconfigured
to remove the energetics, were coprocessed through the
LIC and MPF. Utah regulatory authorities gave per-
mission to do this if the gelled GB rocket processing
rate was reduced further, to 1.0 rocket per hour.
The Army believes that gelled GB rockets could
have been processed through the DFS system at
TOCDF safely and effectively at a faster rate, but this
was not demonstrated. The M55 Committee agrees
with the Army's judgment and recommends that the
Army pursue means to demonstrate the safety of a
faster rate. Another way to process rockets and projec-
tiles containing the same agent is called "complemen-
tary processing." In this variation, rockets are pro-
cessed by themselves for a few days, and then
projectiles are processed by themselves while mainte-
nance is performed on the rocket processing equipment.
Complementary processing was also tried successfully
at TOCDF.
At both JACADS and TOCDF, mandatory trial
burns were undertaken to test for agent destruction and
removal efficiency (DRE) and for emission of metals
or toxic substances such as dioxins and furans. The pre-
scribed 99.9999 percent DRE for agent was met in all
but one of the eight trial burn tests at JACADS. The
temperature and residence time in the DFS afterburner
were increased in the TOCDF (and ANCDF) design to
ensure more complete combustion. In a few tests, mer-
cury and lead emissions exceeded standards at both
JACADS and TOCDF. A PFS is being employed at
ANCDF to ensure compliance with the more stringent
requirements that have since been instituted for control
of emissions. Comprehensive measurements of
ASSESSMENT OF PROCESSING GELLED GB M55 ROCKETS AT ANNISTON
nonagent emissions are made only during infrequent
trial burns. This is in accord with standard industrial
practice and regulatory requirements. As long as the
furnace functions within normal operating limits, these
emissions should not change. However, the M55 Com-
mittee believes that more frequent monitoring could
reassure the public. The lack of similar data for regular
operations makes it difficult to convince the public that
emissions are always within permit limits.
DISPOSAL SCHEDULES FOR ANCDF
The ANCDF Original Plan
The first schedule for disposal operations at ANCDF
called for processing in the following order:
GB M55 rockets
· agent changeover
· VX M55 rockets
· VX munitions
· agent changeover
· GB munitions
· agent changeover
· HD/HT (mustard agent) ton containers and
munitions
This schedule was developed before there was a rec-
ognition that gelled rockets would have to be processed.
After gelled rockets were discovered at TOCDF and it
became clear that there are many of them in the
Anniston stockpile as well, the Army commissioned
experienced furnace consultants who had worked on
the baseline furnaces at JACADS and TOCDF to esti-
mate the rate at which gelled GB rockets could be pro-
cessed through the DFS system. The consultants con-
structed a mathematical model that was necessarily a
simplification of the actual DFS kiln. Backed by some
detailed modeling work, assumptions were made about
how much of the GB, propellant, burster, fuze, and ep-
oxy resin would burn at various points along the DFS
kiln. Based on the modeling, the consultants concluded
that the DFS kiln could safely process up to 34 gelled
rockets per hour. They recommended, however, that
this goal be approached gradually during the GB agent
trial burn period.
The M55 Committee believes the 34 per hour rate is
optimistic, but it supports the idea of ramping up pro-
duction gradually, to a higher rate than was employed
at TOCDF. Some of the committee's concerns about
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EXECUTIVE SUMMARY
the 34 per hour rate are these: (1) the maximum rate of
heat release at the inlet to the DFS may be higher than
assumed in the model; (2) unless properly managed,
the instantaneous rate of heat release may lead to tem-
perature spikes and resultant pressure puffs that could
release agent into the DFS room and/or the ECR; and
(3) agent will probably melt and may then vaporize and
undergo thermal decomposition and oxidation in the
feed chute, since the chute would be hotter than in the
TOCDF runs. This could require limiting the feed rate.
Also, the current DFS instrumentation the Process
Data and Recording System should be reconfigured
and used during the ramp-up period of the agent trial
burn to measure and record instantaneous peak gas tem-
peratures, differential pressures, and feed chute metal
temperatures.
In May 2002, ANCDF successfully conducted trial
burns in the DFS kiln on gelled rocket surrogates (i.e.,
nonagent materials). The DREs were better than the
99.9999 percent permit limit, and emissions of metals,
carbon monoxide, and other toxic materials were within
limits when the PFS was in service. Levels of cadmium,
lead, and mercury exceeded regulatory limits when the
PFS was not in service during some of the surrogate
trial burns, but it will be placed in service during agent
operations. The surrogate trial burn demonstration,
which fed combustibles through the DFS equivalent to
the weight of combustibles in 15 gelled rockets per
hour, suggests that a larger number of rockets contain-
ing gelled agent can be safely processed per hour than
were processed at TOCDF.
The Army has derived another target rate for pro-
cessing gelled rockets based on having only one rocket
in the DFS kiln at a time. At the planned rotation rate of
1.85 rpm, it takes 6.5 min for solids to traverse the kiln
length. This produces a rate of 60/6.5, or 9.2 gelled
rockets per hour. This rate was used in both the original
plan and the modified plan discussed below. It is prob-
ably achievable, but it should be approached gradually
and with a fully instrumented DFS system. Using this
rate, plus the normal rates for the other munitions, the
Army has estimated it would take 7.2 years to process
the entire Anniston stockpile (see Appendix B). As
noted above, there would be three agent changeovers.
During agent changeover operations, all areas exposed
to agent are decontaminated by workers in demilitari-
zation protective ensemble (DPE) suits. Since the
monitors are agent specific, once the area is cleaned so
that the previous agent is nondetectable, they are re-
placed with instruments calibrated for the agent that
s
will be processed in the next campaign. Changeover
operations are labor intensive and typically take about
4 months.
The ANCDF Modified Plan
Based on the successful experience at TOCDF in
coprocessing GB rockets and other munitions, the
Army developed a modified plan for ANCDF. In this
plan, GB munitions are processed in a complementary
manner with GB rockets, gelled or ungelled (see the
description of complementary and coprocessing in
Chapter 3~. The gelled rockets are processed at the rate
of 9.2 per hour as in the original plan, and the drained
ungelled rockets are processed at a rate as high as 32
per hour. The processing sequence in the modified plan
is as follows:
· complementary and coprocessing of GB rockets
and munitions
· agent changeover
· VX rockets
· VX munitions
· agent changeover
· HD/HT ton containers and munitions
This schedule is estimated to take 6.3 years to com-
plete, 10 months fewer than the original schedule. If
gelled rockets are processed at the rate of 1.6 per hour,
demonstrated at TOCDF, complete destruction of the
ANCDF stockpile is estimated to take 7.6 years (see
Appendix B). Although the modified plan would thus
provide more expeditious elimination of the storage
risk from the overall Anniston stockpile, local officials
and members of the public have questioned the safety
of processing gelled rockets at a rate higher than that
used at TOCDF.
Assessment of Public and Worker Risks
Under the Two Plans
QRAs can be used to identify all conceivable acci-
dent sequences that might lead to a harmful release of
agent. For each sequence, a frequency of occurrence
and the potential impacts on public and worker safety
are estimated. Overall risk estimates are computed by
summing over all the individual sequences to give com-
posite expected values of risk over the duration of the
disposal program. QRAs are site specific since the
population densities, terrain, weather patterns, and po-
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6
tential for natural disasters (earthquakes, lightning
strikes, forest fires, etc.) are different at each site. The
QRAs conducted for each site have consistently shown
that the risk of accidental release of agent during stor-
age is larger than the risk during processing. As noted
earlier, different munition-agent combinations repre-
sent different levels of risk, with GB M55 rockets rep-
resenting the highest risk.
Assuming a maximum processing rate of 9.2 gelled
GB rockets per hour, the QRA estimate of the total risk
to the public over the 7.2 years necessary to destroy the
Anniston stockpile according to the original plan is
0.058 expected fatalities. Over the 6.3 years necessary
for the modified plan, which processes gelled GB rock-
ets at the same rate and coprocesses other GB muni-
tions, the total risk is 0.065 expected fatalities. This is
the estimated number of fatalities expected from start
to completion of disposal processing. The total public
risk level in the modified plan if the TOCDF rate of 1.6
rockets per hour is employed climbs to 0.095 expected
fatalities for the 7.6 years necessary to destroy the en-
tire Anniston stockpile. The slightly higher level in the
modified plan results from keeping the VX rockets in
storage an extra 4 months while the remainder of GB
munitions is destroyed. The worker risk assessment has
not been revised for these options, but it seems reason-
able that the elimination of an extra agent changeover
operation will reduce overall worker risk.
If the assumptions made in developing the risk esti-
mates in the QRA are accepted and the inherent uncer-
ASSESSMENT OF PROCESSING GELLED GB M55 ROCKETS AT ANNISTON
tainty surrounding such estimates and the trade-offs
between public and worker risk are taken into account,
it is not possible to differentiate meaningfully between
the processing plan options based on calculated risk
alone. The committee therefore recommends that the
modified plan be undertaken with precautionary ramp-
up of the production rate until a safe upper production
limit is established or the maximum permitted rate is
achieved.
The overall risk from the stockpile is increased by
any programmatic delays, because the risks in storage
increase with time and remain greater than the risks of
disposal operations. Unresolved issues between the
Army and the Chemical Stockpile Emergency Pre-
paredness Program, as well as between the Army and
regulatory groups, need to be addressed expeditiously.
Further, it is important that the Army improve commu-
nications with the local communities, both to promote
a better understanding of the risk issues and to address
any valid public concerns. The health risk assessment
(HRA) for ANCDF has not been completed because
the agent trial burns have not been done. The HRA is
concerned with exposures to possible toxic emissions
other than agent, for example, metals and organic emis-
sions such as dioxins and furans. The Army should
complete the HRA for the ANCDF as soon as feasible.
The fact that emissions in the surrogate trial burns were
low suggests that the agent trial burns will meet rel-
evant standards.
Representative terms from entire chapter:
dfs kiln
