|
Items in cart [0] |
Questions? Call 888-624-8373 |
| Copyright © 2009. National Academy of Sciences. All rights reserved. Terms of Use and Privacy Statement |
Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 197
APPENDIX
CBaseline Disassembly Process
The baseline demilitarization system utilizes incin-
eration to destroy chemical agents and energetic mate-
rials. The Army has spent considerable time and effort
to develop processes for disassembling the chemical
weapons prior to incineration. Many of these processes
are not "incineration-specific," that is, they dismantle
the munitions but do not prepare the dismantled pieces
specifically for incineration. Thus, these processes
could potentially be used as part of alternative disposal
technologies (other than incineration).
Because several of the technology providers have
incorporated the baseline disassembly process into their
proposed technology packages (with some modifica-
tions), the committee included this description of the
overall baseline disassembly process. The storage of
assembled chemical weapons is discussed first to pro-
vide background on packing configurations. Then, the
procedures used to bring munitions to the chemical
demilitarization facility (CDF) from the storage area
and prepare them for disassembly are described. Next,
the actual disassembly of each type of munition (rockets;
projectiles and mortars; and land mines) is explained.
This is followed by a discussion of the special treat-
ment required for munitions that leak during storage or
transport. Finally, some of the problems encountered
during baseline disassembly are described. Note that
the baseline process handles all types of munitions, but
only one type of munition is treated at a time.
iBaseline disassembly is often referred to loosely as "reverse assembly"
because the disassembly of projectiles, in general, reverses the steps used in
their assembly. This description is not accurate for other munitions (e.g.,
M55 rockets), which are not reverse assembled. Therefore, the term reverse
assembly is not used in this report to describe the overall baseline
disassembly process.
197
STORAGE OF MUNITIONS
Assembled chemical weapons are stored on wooden
pallets stacked in igloos protective structures made
of reinforced concrete. The pallet configurations vary
for different types of munitions. M55 rockets, inside
their fiberglass shipping and firing tubes, are stored 15
to a pallet in a 3 x 5 geometry. M23 land mines are
stored in 16-gallon steel drums, three mines per drum,
12 drums per pallet. Projectiles and mortars range from
eight to 24 munitions per pallet, depending on the size
of the rounds.
The igloos are monitored for airborne chemical
agent on a regular basis, and a small but significant
number of munitions have been found to leak over time.
Generally, these are vapor-phase leaks, but leaks of liq-
uid agent have also occurred. When munitions that leak
(called leakers) are identified, they are placed in pro-
tective containers (called overpacks), which act as a
barrier to further leaks to the external environment.
Leaker mines are overpacked in plastic and reloaded
into drums. Leaker rockets, projectiles, and mortars are
placed inside thick steel overpacks that are then
repalletized for subsequent storage.
The handling and disassembly of leaker mines is
essentially identical to the handling of nonleaker mines
because (1) the overpack is not extensive and (2) mine
processing can be easily modified to accommodate the
removal of the overpack. In contrast, the handling and
disassembly of leaker rockets, projectiles, and mortars
is somewhat different than for nonleakers (described in
the section "Processing of Overpacked Munitions"~.
The following description applies to nonleaker
assembled chemical weapons.
OCR for page 198
198
ALTERNATIVE TECHNOLOGIES FOR DEMILITARIZATION OF ASSEMBLED CHEMICAL WEAPONS
TRANSPORT AN D HAN DLI NG PRIOR TO
DISASSEMBLY
At the beginning of the disposal process, palletized
munitions are removed from the storage igloo using a
forklift and loaded into a cylindrical steel vessel known
as an on-site container (ONC). Once the munitions are
inside, the ONC is sealed to contain vapor leaks during
transportation. A truck then takes the ONC from the
storage area to the CDF. Inside the CDF, the ONC is
delivered to the unpack area, where it is sampled for
agent contamination prior to opening. If agent is de-
tected, then the ONC is not opened but is instead pro-
cessed as described in the section "Processing of Mu-
nitions That Leak During Transport." If no agent is
detected, the ONC is opened, and the munitions are
removed. The munitions are then manually separated
from their packaging materials. This process is quite
straightforward for projectiles, mortars, and M55 rock-
ets, which are simply removed from their pallets. Rock-
ets are not removed from their fiberglass shipping/
firing (S/F) tubes.
The unpacking process for M23 land mines is more
involved. First, the mine drums are removed from the
pallet. Then, individual drums (containing three mines
with detached fuzes and activators) are conveyed to the
mine glovebox using a forklift and mechanical lift. The
mine glovebox is an enclosed space that forms a bound-
ary between the unpack area and the explosion-con-
tainment vestibule (ECV). Inside the glovebox, the
drums are unpacked manually. Arming plugs are manu-
ally removed from the mines and, along with fuzes and
activators, are placed into a "fuze box" identical in size
and shape to a mine casing.
Once the unpack operations have been completed,
the munitions (and the mine fuze boxes) are placed,
one at a time, on conveyors. Rockets are oriented nose
first; a special indexing ring located on the S/F tube is
used by the loading machine to ensure this orientation.
In contrast, projectiles are sent to the ECV base-first.
The conveyors transport the munitions into the ECV
and finally into the explosion-containment room (ECR),
where the disassembly process begins. The ECR is
separated from the ECV by blast gates and is designed
to contain the effects of accidental explosions during
the processing of explosively-configured munitions. Once
the munitions enter the ECR, all disassembly operations
take place remotely via mechanical systems.
DISASSEMBLY OF M55 ROCKETS
The disassembly process for the M55 rocket is
shown schematically in Figure C-1. Once in the ECR,
the rocket (in its S/F tube) is conveyed to the punch and
drain station of the rocket-shear machine, which first
drains the agent from the rocket by punching holes
through the exterior of the S/F tube and the rocket. The
agent drains by gravity and is pumped to an agent stor-
age tank. Design requirements call for at least 95 per-
cent of the agent to be drained from the rocket.
When draining is complete, the rocket moves via
conveyor to the shear station of the rocket-shear ma-
chine, where it is cut into eight pieces by a hydrauli-
cally-driven guillotine. A combination of water and
caustic spray cools the shearing blade during the cut-
ting operation. The first cut separates the fuze from the
rest of the rocket, and the other cuts break up the burster
and propellant. The sheared rocket pieces drop into a
hopper and are fed into the deactivation furnace system
where the metal parts are decontaminated and the re-
sidual agent and energetics are destroyed. To avoid
potential detonations, the feed is controlled so the fuze
cannot be in the same furnace section as the burster or
propellant segments.
The baseline rocket disassembly system described
above produces two material exit streams: (1) liquid
chemical agent; and (2) sheared rocket pieces contain-
ing metal, residual agent, burster energetics, intact
fuzes, propellant, and fiberglass from the S/F tube.
DISASSEMBLY OF PROJECTILES AND
MORTARS
Figure C-2 shows the disassembly process for pro-
jectiles and mortars. Inside the ECR, the projectile (or
mortar) is conveyed to the projectile/mortar disassem-
bly machine, which removes the explosive components
from the munition in three steps: (1) the fuze and
booster (or lifting plug) are unscrewed from the shell
using a hydraulic chuck at the nose-closure removal
station, (2) the fuze well cup is unscrewed using a hy-
draulically-driven collet at the miscellaneous parts-re-
moval station, and (3) the burster is removed using
high-pressure air at the burster-removal station. Burst-
ers are subsequently sheared into pieces by the burster
size-reduction machine, a modified version of the
rocket-shear machine. The fuze, booster, and sheared
OCR for page 199
APPENDIX C
Unpack area
Rocket metering
table
\
Explosion
, containment;
. vestibule
' /~
Pallet of 15 M55
rockets in firing tubes
FIGURE C-1 Baseline disassembly of MSS rockets.
I Explosion-containment
room
1
l
I Explosion-
containment
vestibule
1
l
Unpack area
FIGURE C-2 Baseline disassembly of projectiles/mortars.
199
Explosion-containment
room
Rocket-shear
machine
. ~
Agent drain
pipe
Munition processing bay
Feed chute for
/sheared rocket
pieces
~To deactivation
To agent furnace system
storage tank
To metal parts
furnace
Multipurpose
demilitarization
machine ~ ~
To agent
storage tank
Projectile/mortar
disassembly
machine
- nose-closure removal station
- miscellaneous parts-removal station
- burster removal station
To deactivation
furnace system
OCR for page 200
200
ALTERNATIVE TECHNOLOGIES FOR DEMILITARIZATION OF ASSEMBLED CHEMICAL WEAPONS
burster pieces are then fed to the deactivation furnace
system for incineration.
The munition, with its explosives removed but its
agent load still in place, then exits the ECR. Using con-
veyors and pick-and-place robots, the munition is trans-
ported to the munitions processing bay, where it is
loaded into the multipurpose demilitarization machine.
At the pull-and-drain station of this machine, a collet is
inserted into the projectile, and the burster well is ex-
tracted. Some burster wells are welded in place, so the
multipurpose demilitarization machine also has a bore
station for milling out the weld or the entire well, as
necessary. Once the burster well is removed (or milled
out), a drain tube is inserted into the shell body, and the
agent is pumped from the munition, through a strainer,
and into an agent storage tank. Design requirements
call for at least 95 percent of the agent to be drained
from the projectile or mortar. Following draining, the
burster well is crimped (to prevent reseating) and
placed back into the munition body. The munition then
moves on to the metal-parts furnace for thermal decon-
tamination to a 5X condition.
Explosion-contai n ment
vestibule
Glovebox
Explosion
containment room
~8 j) Mine
Mine conveyor If)
Air: ~,~
Container
with 3 mines
FIGURE C-3 Baseline disassembly of land mines.
The baseline projectile/mortar disassembly process
produces three material exit streams: (1) liquid chemi-
cal agent; (2) energetic components, including sheared
burster pieces, intact fuzes, and supplementary charges;
and (3) metal munition bodies containing some residual
agent but no energetics.
DISASSEMBLY OF M23 LAND MINES
The process for disassembling land mines is shown
in Figure C-3. In the ECR, the mine is transported to
the mine machine, which is precisely oriented to avoid
the explosive components, and is punched through its
side. At least 95 percent of the chemical agent is
drained and pumped to a holding tank. The mine is
then moved to the booster push-out station, where the
central booster is removed. The mine body and booster
are fed separately to the deactivation furnace system
where the metal parts are decontaminated and the re-
sidual agent and energetics are destroyed.
Mine fuze boxes that enter the ECR are dumped di-
rectly into the deactivation furnace system, and the
To agent
storage tank
_' -
Push-out
station
al /
To deactivation
furnace system
~~ Dunnage to dunnage incinerator;
drums to metal-parts furnace
OCR for page 201
APPENDIX C
fuzes, activators, and arming plugs are destroyed. A
magnet is used to differentiate between the mines and
the plastic fuze boxes. Empty mine drums, unloaded in
the mine glovebox, are sent to the metal-parts furnace
for thermal decontamination.
The mine disassembly process yields five material
exit streams: (1) liquid chemical agent; (2) boosters;
(3) metal mine bodies containing energetics and some
residual agent; (4) plastic fuze boxes containing intact
fuzes, activators, and arming plugs; and (5) steel mine
drums.
DISSASSEMBLY OF OVERPACKED MUNITIONS
Leakers (rockets, projectiles, and mortars) that have
been overpacked require special processing because of
the increased risk of agent contamination. Like non-
leakers, overpacked munitions are stored on pallets.
Therefore, the procedures for removing them from an
igloo and transporting them to the CDF are identical.
Because of the overpacks, however, the machines nor-
mally used to load the rockets, projectiles, and mortars
onto the standard transport conveyors cannot be used.
Instead, the entire pallet of overpacked leakers is loaded
manually onto a bypass conveyor in the unpack area
and conveyed through an airlock into the ECV. There,
operators in demilitarization protective ensemble
(DPE) suits manually unpack the pallet, remove the
rockets, projectiles, or mortars from their overpacks,
and load the munitions onto the conveyors to the ECR.
These munitions are unpacked in the ECV rather than
in the unpack area to ensure agent containment. Once
the leakers enter the ECR, the disassembly steps are
identical to those already described for nonleakers.
DISASSEMBLY OF MUNITIONS THAT LEAK
DURING TRANSPORT
The act of transporting munitions from the storage
area to the CDF may cause some munitions to leak.
These munitions are referred to as leaking munitions,
as opposed to leakers, which have leaked during stor-
age and have been overpacked. To identify leaking
munitions, the internal atmosphere of the ONC is moni-
tored prior to opening it in the unpack area. If agent is
201
toxic maintenance area. This area is a "Level
A" area,
which means that liquid and airborne agent contamina
tion is expected, and operators wear DPE suits. Thus,
the ONC can be opened safely in this area.
After opening, the pallets are removed, and the ONC
and the exterior of the munitions/pallets are decontami
nated using decontamination solution. The pallet is then
loaded onto a special tray and conveyed backwards
through the facility via the processing conveyors. This
means that the pallet is taken from the toxic mainte
nance area (on the first floor of the CDF) up to the
ECV (on the second floor of the CDF), traveling oppo
site to the "normal" conveyor direction for nonleaking
munitions. When the pallet reaches the ECV, operators
in DPE suits manually unpack it and load the muni
tions onto the conveyor to the ECR. Once the leaking
munitions enter the ECR, the disassembly steps are
identical to those already described for nonleaking
munitions.
PROBLEMS ENCOUNTERED DURING BASLINE
DISASSEMBLY
At the Johnston Atoll (chemical Agent Disposal Sys
tem (JACADS) in 1994, an M55 rocket burster initi
ated during shearing (SAIC, 1996). The explosion con
tainment functioned as designed, and no agent was
released from the facility. However, damage to the dis
assembly machines was extensive. The system opera
tion was subsequently modified to ensure that water
sprays were irrigating the cutting zone during all shear
ing operations.
During operational verification testing at JACADS,
the multipurpose demilitarization machines (used to
pull the burster wells and drain the agent from projec
tiles and mortars) were found to be among the least
reliable of the baseline equipment. They required a
large number of toxic-area entries (and even continu
ous manning) by personnel in DPEs (Mitre, 1993).
Subsequent modifications have improved their reliabil
ity, but quantitative data on the degree of improvement
were not available.
Some difficulties have also been encountered in un
screwing the nose closures on projectiles. Apparently,
the pitch on the nose closure threads varies, and the
detected, the ONC is conveyed outside the facility and projectile/mortar disassembly machines were some
taken, via a separate entrance, into an area called the times unable to unscrew the nose closures. Most of the
OCR for page 202
202
ALTERNATIVE TECHNOLOGIES FOR DEMILITARIZATION OF ASSEMBLED CHEMICAL WEAPONS
problems with projectile/mortar disassembly were
solved by making slight modifications to the baseline
disassembly equipment; however, as of 1996, between
5.1 and 8.6 percent of the projectiles processed were
rejected because of some failure in the disassembly
process (PMCD, 1997). (The percentage varied with
the type of projectile. )
Currently, JACADS is processing mustard-filled
4.2-inch mortars. The agent in these mortars has be-
come very thick and cannot be drained using the
baseline suction approach. Therefore, after the agent
cavity is opened, these rounds are being introduced to
the metal-parts furnace at a reduced rate. The agent
volatilizes from the mortar in the furnace and is ther-
mally destroyed. JACADS is currently investigating a
modification to its environmental permit to allow more
agent per tray of mortars into the metal-parts furnace
thus, increasing the throughput rates.
REFERENCES
Mitre. 1993. Summary Evaluation of the Johnston Atoll Chemical
Agent Disposal System: Operational Verification Testing.
MTR93W0000036, May 1993. McLean, Va.: Mitre
Corporation.
PMCD (Program Manager for Chemical Demilitarization). 1997.
Presentation by PMCD representatives from JACADS to the
Committee on Review and Evaluation of the Army Chemical
Stockpile Disposal Program. Honolulu, Hawaii. June 23, 1997.
SAIC (Science Applications International Corporation). 1996.
Tooele Chemical Agent Disposal Facility Quantitative Risk
Assessment. SAIC-96/2600, December 1996. Abingdon, Md.:
Science Applications International Corporation.
Representative terms from entire chapter:
chemical agent
