Rocky Flats Plant,
Plutonium Recovery Facility
HAER No. CO-83-K (Rocky Flats Plant, Building 371)
Rocky Flats Environmental Technology Site, Highway 93, Golden, Jefferson
County, Colorado. Building 371 is located in the northwestern portion of the Rocky Flats
Date of Construction: 1981.
Fabricator: Frank Briscoe.
Present Owner: U.S. Department of Energy (DOE).
Present Use: Plutonium Recovery.
This building is a primary contributor to the Rocky Flats Plant
historic district, associated with the U.S. strategy of nuclear military
deterrence during the Cold War, a strategy considered of major importance in preventing
Soviet nuclear attack. Building 371 was originally built to replace plutonium recovery
operations in Buildings 771 and 776, using advanced technology for plutonium handling,
recovery, and safety. The design was far more sophisticated and complex than any others at
the plant. It was designed to emphasize automatically controlled, remotely operated
processes, in contrast to the direct, hands-on operations in Building 771. Building 371
was designed in 1968 and construction was completed in 1981, but the design did not meet
new safeguard and security requirements implemented in 1976. The plutonium recovery
process never ran at full capacity, and after 1983, the recovery operations ceased
In 1995, an inventory and an evaluation was conducted of facilities at the Rocky Flats
Plant for their potential eligibility for listing in the National Register of Historic
Places. The primary goal of this investigation was to determine the significance of the
Cold War era facilities at the plant in order to assess potential effects of the long-term
goals and objectives of DOE. These goals and objectives have not yet been
formalized, but include waste cleanup and demolition activities. Recommendations regarding
National Register of Historic Places eligibility were developed to allow DOE to
submit a formal determination of significance to the Colorado State Historic Preservation
Officer for review and concurrence and to provide for management of historic properties at
From this determination and negotiations with the Colorado State Historic Preservation
Officer, the Advisory Council, and the National Park Service, a Historic American
Engineering Record project began in 1997 to document the plants resources prior to
their demolition. The plant was listed on the National Register of Historic Places in
1997. The archives for the Historic American Engineering Record project are located in the
Library of Congress in Washington, D.C.
The plant is one of 13 DOE facilities that constitute the Nuclear Weapons
Complex, which designed, manufactured, tested, and maintained weapons for the U.S.
arsenal. The plant was established in 1951 to manufacture triggers for use in nuclear
weapons and to purify plutonium recovered from retired weapons. The trigger consisted of a
first-stage fission bomb that set off a second-stage fusion reaction in a hydrogen bomb.
Parts were formed from plutonium, uranium, beryllium, stainless steel, and other
A tense political atmosphere both at home and abroad during the Cold War years drove
U.S. weapons research and development. By the 1970s, both the U.S. and the Soviet Union
maintained thousands of nuclear weapons aimed at each other. These weapons were based on
submarines, aircraft, and intercontinental ballistic missiles. Both the North Atlantic
Treaty Organization and Warsaw Pact countries in Europe had small nuclear warheads known
as theater weapons used as part of the Mutually Assured Destruction program. (The Mutually
Assured Destruction program acted as a deterrent in that if one side attacked with nuclear
weapons, the other would retaliate and both sides would perish.) The final nuclear weapons
program at the plant was the W-88 nuclear warhead for the Trident II missile. This mission
ended in 1992 when President Bush canceled production of the Trident II missile.
The plant was a top-secret weapons production plant, and employees worked with a
recently man-made substance, plutonium, about which little was known concerning its
chemistry, interactions with other materials, and shelf life. The Historic American
Engineering Record documentation effort focused on four aspects of the plant and its role
in the Nuclear Weapons Complex: manufacturing operations, research and development, health
and safety of workers, and security.
|Chronology of Building 371:
||The decision was made to replace the Building 771/774 Plutonium
Recovery Facility with the
Building 371/374 Complex.
||The construction plan for Building 371 was authorized.
||Site preparation, groundbreaking, and fencing for building
||The building was originally scheduled for start-up, however,
construction was temporarily halted due to problems with the construction
||Waste treatment operations began in Building 374.
||Waste treatment in Building 374 began handling non-radioactive
wastes from Building 371. The wastes were generated from start-up testing operations of
||Construction of Building 371 was completed. DOE authorized
radioactive operations. Plutonium pyrochemical recovery operations (molten salt
extraction) began on a limited basis. The first electrorefining run in the tilt-pour
|| Pilot-scale aqueous plutonium operations began, including
recovery in March and primary purification in April. Initial full-scale operations of the
aqueous recovery system began in August.
||The plant produced the first plutonium metal processed entirely
through the buildings aqueous recovery system. The Plutonium Recovery Modification
Project was established as a result of plutonium inventory accountability problems during
pilot-scale operations in the aqueous recovery process. Its purpose was to identify
processing deficiencies in Building 371 and to design replacement processes. Aqueous
recovery operations ceased in April.
|| The site contractor submitted the Conceptual Design Report to
DOE detailing modifications needed to bring Building 371 into full operation.
||Electrorefining activities ceased. Approximately one-half of the
processes that were originally operating in the building had been shut down by this date.
The last major recovery operations terminated.
||Pyrochemical processing ceased.
||Funding for replacement plutonium recovery processes for
Building 371 was denied by U.S. Congress.
Building 371 was originally built to replace plutonium recovery operations in Buildings
771 and 776, using advanced technology for plutonium handling, recovery, and safety.
Although fundamentally based on the processes and principles developed previously in
Building 771, the design of Building 371 incorporated many technological advances and
refinements. The design was far more sophisticated and complex than any others at the
plant. Building 371 was designed to emphasize automatically controlled, remotely operated
processes, in contrast to the direct, hands-on operations in Building 771. The projected
operations for the building focused primarily on recovery of plutonium from both solid and
liquid wastes. The final product from the process operations was intended to be recycled
plutonium metal, which was to be reused in the plant's primary manufacturing process.
Building 371 was originally scheduled to be completed in 1976 and to cost approximately
$70 million. The stacker-retriever, a remotely operated, mechanized transport system to
move plutonium storage drums, became operational in 1976. In 1980, the heating, venting,
and air-conditioning systems were brought on-line and start-up testing operations using
nonradioactive solutions began. The rest of the building was finally completed in 1981
for a total cost of approximately $214 million. Limited pyrochemical plutonium recovery
operations began in 1981.
In 1982, pilot-scale aqueous plutonium recovery operations began in Building 371. There
were not enough operators to run the process continuously, so the process was run in
batches, shutting down one phase to start the next. Employees were to be transferred to
the new facility when it was fully operational and Building 771 was shut down.
One year after the aqueous recovery process began, DOE conducted an inventory of
the plutonium at the plant, and Building 371 inventory was found to be deficient. The
building had more than 770 miles of piping, of which 70 miles were plutonium processing
lines. Process lines ran through walls and traversed several floors. In the 1960s,
plutonium inventories were calculated by the amount of material that went into the process
and the amount that came out; the amount residing in the process was estimated. By 1976,
accountability was required for every gram of material at all times; estimating the amount
of plutonium residing in the process was no longer acceptable. The aqueous process was
shut down until all in-process plutonium could be located. The majority of the material
was found. Designed in 1968, Building 371 was not constructed to meet this type of
safeguard and security requirement. Although several projects to upgrade the system were
proposed, none were approved. The process never ran at full capacity nor did the process
ever again become operational after 1983.
Building 371 was designed to emphasize the use of automatically controlled, remotely
operated processes. Design features included the use of remotely operated transfer systems
for movement of radioactive materials. The stacker-retriever, a computer-operated,
rail-mounted shuttle moved radioactive material between storage and plutonium recovery
The plutonium handling areas of the building are compartmentalized by fire walls,
airlocks, and the use of negative air pressure to prevent the spread of plutonium from one
area to another. The compartments are further divided into rooms, canyons, and vaults.
Rooms were used to house glove box operations and equipment that did not require special
containment precautions. Canyons were used to house plutonium handling operations that
were not contained within glove boxes. Process equipment within the canyon was remotely
operated; the canyon and all the equipment inside were contaminated with plutonium.
Vaults are essentially storage areas that are designed to prevent criticality of stored
plutonium-containing materials. To prevent nuclear criticality, storage racks hold
containers in a safe geometry, and tanks and containers within the vaults are of a safe
geometry, or are filled with boron-glass Raschig rings. Tanks in certain areas are located
behind 2-foot-thick concrete walls, which helped to shield personnel from radiation in the unlikely
event of a nuclear criticality.
Building Layout: Building 371 is a four-level partially buried structure constructed of reinforced
concrete. It encompasses approximately 186,000 square feet of floor space. The building
construction was hardened to withstand the forces imposed by a design-basis earthquake or
tornado. The hardened construction includes the exterior walls and roof, those parts of
the building where plutonium recovery operations were conducted, and portions of the
building that housed equipment or systems essential to the recovery processes or were
required to contain plutonium within the building.
The sub-basement, the bottom level, is an irregularly shaped area, consisting primarily
of the lower portion of the plutonium storage vault and its transfer, repair, and the
stacker-retriever maintenance bays. Areas at the east end contain the lower parts of the
glove box scrubbers, the incinerator vent scrubber, and the filtration process area, plus
utility equipment for the sub-basement. The sub-basement measures 364 feet (east to west) by
180 feet (north to south).
The east end of the sub-basement contains a stacker-retriever transfer bay, Room 1220;
a repair bay, Room 1218; a maintenance bay, Room 1216; a preventative maintenance bay,
Room 1224; and three airlocks (Rooms 1214, 1222, and 1230). These provided space and
equipment to service the stacker-retriever and to house a spare stacker-retriever. Glove
boxes in the preventive maintenance bay allowed access for repairs to stacker-retriever
electronic systems. The sub-basement has hardened walls and a nitrogen atmosphere. The
repair bay can be entered through an airlock, but before entering, the bay must be closed
off and the nitrogen atmosphere must be replaced with breathable air. This allowed
personnel access to make repairs to the mechanical systems of the stacker-retriever.
Extending from the sub-basement upward to the ground floor level, is Room 1206, the
plutonium storage vault. The vault, which provided temporary storage for plutonium
compounds, is a long narrow chamber with approximate dimensions of 300 by 15 by 40 feet. Vault
walls are 14-feet-thick concrete. The vault has an array of 1,428 metal storage bins attached
to the full length and height of the side walls, with a single open aisle down the center.
Each bin holds a 4 by 4 foot metal pallet, which has cylindrical holders for plutonium storage
containers. For criticality safety, the cylindrical holders are at predetermined
locations, and the storage containers are double-walled and water-filled. To access the
containers, the stacker-retriever is mounted on rails that run the length of the aisle
between two rows of bins. At one end of the vault, the rails end in a large transfer
bay that connects to the repair and preventive maintenance bays.
The basement houses heating, venting, and air conditioning equipment and mechanical
utilities, the upper part of the plutonium storage vault and maintenance bay, and small
plutonium processing areas. The basement level is divided into nearly equal north and
south parts by the upper portion of the plutonium storage vault. The basement is 330 feet
(east to west) by 250 feet (north to south); it extends to the south nearly 70 feet under the
ground floor of the office areas in the southern portion of the building. In the northeast
section, Room 2327, is a portion of the incinerator vent scrubber canyon; Rooms 2325 and
2321 are the dissolution process area and control room. The upper parts of two glove box
ventilation scrubbers are in the basement, one on the north side and one on the south
The ground floor contained the majority of the plutonium recovery processes and office
space. The office space, located along the southern length of the building, is segregated
from the plutonium handling areas of the building by hardened construction.
The plutonium processing areas of the ground floor are divided by hallways into six
compartments. The compartments are constructed of noncombustible materials, and have at
least a two-hour fire rating to prevent the spread of fire, and to limit potential
contamination from a fire to a single area. Each of the compartments is further subdivided
into modules or rooms, and within the modules or rooms, the plutonium processing equipment
is contained in glove boxes, canyons, or vaults. The purpose of these enclosures within
enclosures was to contain particulate radioactive material and shield operating personnel
The northwest compartment contains equipment for aqueous and pyrochemical plutonium
recovery processes. This compartment is divided into two modules (north and south). The
north module is further divided into two canyons, one vault, and nine other rooms. The
south module is further divided into four rooms.
The southwest compartment is divided into two vaults, a control room, and an area for
processing site returns. Site returns were nuclear weapons returned to the site for
upgrade or retirement.
The north central compartment contains equipment for aqueous recovery operations, and
storage areas for plutonium oxides and residues from the aqueous recovery operations. This
compartment is divided into two modules (north and south) and three other rooms. The
north module is further divided into 2 vaults, 2 canyons, and 12 other rooms. The
south module is further divided into four canyons and nine other rooms.
The south-central compartment is divided into 13 rooms that included analytical
and standards laboratories, the health sciences group, decontamination areas,
heater rooms, and a backlog barrel storage area.
The northeast compartment is divided into three canyons and four other rooms. Two of
the canyons house incinerators; the third canyon houses a scrubber system for the
incinerators. The rooms house residue loading and unloading operations and control
operations for the canyons.
The southeast compartment is divided into two rooms. The southeast compartment was used
for shipping and receiving of plutonium and plutonium-containing materials, and a high-bay
drum storage area for residues with high levels of radioactivity.
The attic, level four, provides protected space for air distribution systems, chemical
piping, electrical conduit, and two motor-generator sets.
Transfer Systems: Building 371 is equipped with two systems for the transfer of radioactive materials.
The pneumatic transfer system was used to transfer materials of moderate to low
radioactivity. The vacuum transfer system was used to transport highly radioactive
Pneumatic Transfer System: The pneumatic transfer system consists of 24 transfer lines of 2 sizes and
uses pneumatic pressure to move materials. The smaller line is 1 inch by 3 inch (inner
dimension), is made of polyethylene, and was used to transfer liquid and solid samples.
The larger line is 3 inch by 12 inch (inner dimension), is made of polycarbonate, and was
used to transport used filters. The pneumatic transfer system was used to transfer
materials between the basement and ground floors.
Vacuum Transfer System: The vacuum transfer system consists of 31 lines, and uses differential pressure
to move highly radioactive materials. Two of the lines also use argon and nitrogen
pressure as well as vacuum as the motive force. These two lines need the additional force
to keep the material in a fluidized state during transfer. The
vacuum transfer system was used to transfer materials between the sub-basement, basement,
and ground floors.
A typical bulk vacuum transfer system consists of a hand-held pick-up wand, pick-up
vessel (or slop pot), conveyor tube (0.75-inch or 1.5-inch diameter welded stainless
steel), cyclone separator, filters, material receiver, and process vessel. The system also
has high- and low-level sensors, valves, switches, and indicator lights, all interlocked
and tied into local control sequence panels.
Incinerators: There are two incinerators and afterburners in separate concrete canyons that
were used for burning wastes: one in Room 3713 for high specific activity waste, and the
other in Room 3715 for low specific activity waste. Due to the size and shape of the
incinerators, they span multiple levels (basement to attic). Feed material entered the
incinerators at ground floor level. The high specific activity waste incinerator is an oil-fired, refractory-brick-lined,
rotary kiln that can burn both liquid and solid line-generated waste from plutonium
processing buildings. The revolving cylinder is horizontal, but it can be adjusted through
a series of angles from the horizontal to control the rate of material flow. Ash and
residue from the high specific activity incinerator was further processed for plutonium
recovery. The low specific activity incinerator is an oil-fired, raked-hearth, stationary,
vertical furnace lined with refractory brick. It has forced-air-cooled rabble arms
rotating on a central vertical shaft. The arms swept material across a stationary hearth
plate during burning. Ash and residue from the low specific activity incinerator were
packaged for disposal.
The plutonium recovery facility, Building 371, is one of five buildings that comprise
the Plutonium Recovery and Waste Treatment Complex. The other buildings in the complex are
Building 372, a guard post; Building 373, a cooling tower; Building 374, a waste treatment
facility; and Building 381, fluorine gas storage. Utility lines, roads, drainage control
structures, and fencing also constitute part of the total complex.
Operations in Building 371 focused on the recovery of plutonium from plant activities
(nuclear weapons parts fabrication, component assembly, and research and development
activities). Americium, a decay by-product of plutonium, was separated from plutonium and
recovered for resale. Other operations included material transfer, waste incineration, and
Plutonium Recovery: Plutonium recovery operations used two different systems to separate high-purity
plutonium metal from production-generated wastes. Pyrochemical processing used furnaces
and molten salts to separate high-purity plutonium in a dry process. Pyrochemical
processing was efficient, but could not be used in all situations. Aqueous processing used
a series of wet and dry chemical steps to separate high-purity plutonium from production
Materials entering the plutonium recovery process were received as pieces of impure
plutonium metal, plutonium oxide, various compounds containing plutonium, and
plutonium-contaminated residues. The plutonium content of these materials ranged from a
few percent to almost pure plutonium metal. The plutonium and americium content of the
residues was reduced by the recovery processes to a level below the economic discard
Pyrochemical Plutonium Recovery: Metal plutonium was processed through a pyrochemical operation in which americium was
extracted from plutonium by direct contact with molten salts, yielding a plutonium button
low in americium. If other impurities had to be removed, the extracted metal went to an
electrorefining process where the plutonium was transformed by electrolysis in a
molten-salt bath, resulting in an impure plutonium heel, contaminated salt, and product
metal of very high purity. Impure metal was burned, converting it to an oxide, and
processed through the aqueous chemical recovery systems. The high-purity plutonium button
was transferred to the Building 707 foundry operations for casting and weapon component
fabrication. Contaminated salts were transferred to Building 771 for americium separation
and plutonium recovery.
Aqueous Plutonium Recovery: Plutonium oxide and other materials required a series of wet and dry chemical
processing steps to produce a plutonium button of high purity. As a first step, the oxide
and other materials were dissolved in nitric acid in a series of cascade dissolution pots.
The plutonium-containing acid solutions from the dissolution process were blended into a
nitric acid feed which was pumped through anion-exchange resin columns. The anion-exchange
resin selectively absorbed plutonium ions while allowing certain other metallic ions to
pass through. Americium formed a weak bond with the resin, allowing selective segregation
of some americium from the plutonium-rich stream. Solutions high in americium were
segregated for further processing in americium recovery, and the remainder went through a
secondary recovery process.
The anion-exchange eluate was concentrated in an evaporator. The evaporator concentrate
fed into a line of precipitation vessels where the plutonium was precipitated as plutonium
peroxide. The precipitate was filtered and the filtrate recycled through anion exchange.
The precipitate was transferred to a calcining furnace where the plutonium peroxide was
converted to plutonium oxide by heating. The dry plutonium oxide was pneumatically transported to a fluidized-bed reactor in the
direct fluorination canyon (Room 3523). The plutonium oxide was contacted with a
fluorine-argon gas mixture to keep it fluidized while converting it to plutonium
tetrafluoride. When the reaction was complete, the plutonium tetrafluoride was transported
to a receiving chamber in the reduction canyon (Room 3515). Calcium metal was measured into reduction vessels, and the plutonium tetrafluoride was
added. The reduction vessel was sealed in an induction furnace and heated to initiate a
reduction reaction that yielded a pure plutonium metal button and calcium fluoride slag.
The plutonium button was sampled, stamped, and shipped as product. The calcium fluoride
slag was recycled as cascade dissolver feed.
A process line was installed in the building to recover americium from solutions
isolated during the anion exchange loading steps. Although the system was never fully
operational, it was designed to operate as follows. The solutions were to be alternately
evaporated and diluted to reduce the nitric acid concentration. Then, sets of anion and
cation exchange columns, operated in series, were to be used to purify the concentrated
americium solution. Next, oxalic acid was to be added to the concentrate to precipitate
americium oxalate. The precipitate was collected in a filter boat and calcined to convert
it to americium dioxide. Americium was a saleable product used in medical diagnostic
tracer procedures, in ionization-type smoke detectors, and in static eliminators.
Laboratories: Building 371 housed plutonium analytical laboratories and a chemical standards
laboratory, which supported operations throughout the plant. The plutonium analytical
laboratories served Buildings 371 and 374, and acted as backup for the Building 771
analytical laboratory. The majority of the work at this laboratory consisted of total
alpha and beta counts along with radiochemical analyses for specific isotopes in liquid
and solid samples. These analyses served as a screen to identify highly radioactive
samples which were unsuitable for detailed analysis in Building 881.
The chemical standards laboratory prepared both nondestructive assay and destructive
assay standards for various user groups at the plant and inspected standards used in the
field. Most laboratory operations took place in glove boxes. Nondestructive assay
standards were prepared for plutonium, americium, and uranium oxides and metals (including
beryllium) for a wide range of instrumentation.
Incinerators: The low specific activity waste incinerator burned all combustible waste generated
outside glove boxes or hoods from plutonium process buildings throughout the plant. Solid
waste was burned to reduce volume. The resulting ash was packaged for disposal.The high specific activity waste incinerator burned waste generated within glove boxes
and hoods from plutonium processing buildings. Both solid and liquid wastes were burned.
The resulting ashes were analyzed by radiometric counting methods for plutonium content,
classified, and subjected to appropriate plutonium recovery processes.
Pneumatic Transfer System: The pneumatic transfer system transferred process filters from glove boxes associated
with metal and glass leaching, pyrochemical salt dissolution, and dissolution filtration
processes to the high specific activity incinerator glove box. Process material samples
(liquid and solid) were transferred from process glove boxes to laboratory glove boxes for
Before transfer, contaminated filters and samples were containerized, filters were
sealed in plastic bags, and samples (liquid or solid) were placed in bottles with screw-on
caps. The bagged filter or the bottled sample was placed inside a carrier, which also had
a screw-on cap, providing double containment for the material. The closed carrier was then
placed in the loader-receiver and sent to the opposite end of the pneumatic system. When
the loader-receiver arrived, the door was opened, the carrier removed and opened, and the
bagged filter or the bottled sample taken out.
Vacuum Transfer System: The vacuum transfer system transported highly radioactive materials between recovery
processes, from the plutonium storage vault to recovery processes, and to and from
shipping and receiving areas. The bulk liquid or solid was pulled into the transfer pipes
and moved using the pressure differential created by the vacuum pumps. These radioactive
materials were transferred in measured batches. Before a transfer was made, the operator
ensured there was adequate space in the receiving vessel, and that the receiving vessel
discharge valve was closed.
When bulk transfer conveyor tubes passed outside glove boxes or canyons, secondary
containment was provided by enclosing the conveyor tubes within welded stainless steel
pipes. The stainless steel pipes had ports for contamination monitoring. Gas-tight
barriers at intervals along the pipes separated the secondary containment space at one end
of the system from that at the other end.
Stacker-Retriever: Storage and retrieval of plutonium metal and solid residues was accomplished by using
the stacker-retriever. The stacker-retriever moved materials between the shipping and
receiving areas, the plutonium storage vault, and the plutonium recovery processing areas.
Operations Since 1989:
Since operations ceased at the plant in 1989, operations in Building 371 have focused
on waste and special nuclear material handling and storage and on laboratory operations.
Buffer, Patricia. 1995. "Highlights in Rocky Flats History".
Rocky Flats Repository. Golden, Colorado.
Colorado Department of Health. Project Tasks 3 & 4 Final Draft Report.
Reconstruction of Historical Rocky Flats Operations and Identification of Release Points
(1992), by ChemRisk. Rocky Flats Repository. Golden, Colorado.
Crisler, L. R. 1991. "Rocky Flats Plant Plutonium Recovery Reference
Process." for EG&G Rocky Flats, Inc. Rocky Flats Repository. Golden, Colorado.
Daggy, David, employed at the plant since 1981 by the site contractor. Personal
communication, September 1997.
United States Department of Energy. Building Histories - Historical Release Report
(1994), by EG&G Rocky Flats, Inc.
Rocky Flats Plant Repository. Golden, Colorado,
United States Department of Energy. Final Site Safety Analysis Report - Building
371, Rocky Flats Plant Repository. Golden, Colorado,1989.
United States Department of Energy. Final Cultural Resources Survey Report (1995), by Science Applications International Corporation. Rocky Flats Repository. Golden,
Weaver, Jack, employed at the plant since September of 1961 by the site contractor.
Personal communication, August 1997 and February 1998.
D. Jayne Aaron, Environmental Designer, engineering-environmental
Management, Inc. (e2M), 1997. Judith Berryman, Ph.D., Archaeologist, e2M
Index to Photographs
Located in the northwest portion of the Rocky Flats Plant, Golden Vicinity, Jefferson County, Colorado.
CO-83-K-1 – Aerial view looking south-southeast at Building 371 under construction. The building is a multilevel structure, partially underground. The plutonium storage vault extends from the west side of the building. Footers for Building 374 are visible to the left of Building 371. (5/2/74)
Photographs CO-83-K-1 through CO-83-K-20 were taken by various site
photography contractors, dates are indicated
CO-83-K-2 – Aerial view looking north-northeast at the subbasement of Building 371 under construction. The subbasement, the bottom level, is an irregularly shaped area consisting primarily of the lower portion of the plutonium storage vault and its transfer, repair, and stacker-retriever maintenance bays. The plutonium storage vault runs east-west. (7/2/74)
CO-83-K-3 – Aerial view looking south at Building 371 basement under construction. The basement houses heating, ventilation, and air conditioning equipment and mechanical utilities, the upper part of the plutonium storage vault and maintenance bay, and small plutonium processing areas. The basement level is divided into nearly equal north and south parts by the upper portion of the plutonium storage vault. (10/7/74)
CO-83-K-4 – Aerial view looking south-southwest at Building 371 ground floor under construction. The ground floor, which contains the majority of the plutonium recovery processing equipment, is divided into compartments by firewalls, airlocks, and use of negative air pressure. (1/7/75)
CO-83-K-5 – Aerial view looking north at Building 371 after construction was completed. (11/7/78)
CO-83-K-6 – View of Building 371 exterior wall construction detail. Building construction was hardened to withstand the forces imposed by a design-basis earthquake or tornado. (7/1/74)
CO-83-K-7 – View of airlock entry. Airlock double doors were used to keep atmospheres confined to specific areas. (6/29/78)
CO-83-K-8 – View of residue storage door. (6/24/78)
CO-83-K-9 – View of closed carrier lines for moving contaminated process filters and transporting solid and liquid material samples. (9/10/96)
CO-83-K-10 – View of piping. The building had over 700 miles of piping, of which 70 miles were plutonium processing lines. These processing lines ran through walls and traversed several floors. (6/29/78)
CO-83-K-11 – View of the tanks for storage of plutonium-containing solutions. The tanks are in a vault. (1/80)
CO-83-K-12 – View of remotely operated equipment. Operators viewed the equipment through a water-filled window. (10/8/81)
CO-83-K-13 – Side view of the stacker-retriever crane from the transfer bay. The stacker-retriever is a remotely operated, mechanized transport system for retrieving plutonium containers from the storage vault. (1/80)
CO-83-K-14 – End view of the plutonium storage vault from the remote control station. The stacker-retriever, a remotely operated, mechanized transport system, retrieves containers of plutonium from safe geometry pallets stored along the length of the vault. The stacker-retriever runs along the aisle between the pallets of the storage chamber. (3/2/86)
CO-83-K-15 – View of the safe geometry plutonium metal storage pallets from the inside of an input-output station. Individual containers of plutonium are stored in the water-filled, double-walled, stainless steel tubes that are welded onto the pallets. (12/3/88)
CO-83-K-16 – View of glove box workstations within the plutonium button breakout room. (9/82)
CO-83-K-17 – View of the first plutonium button produced from the Building 371 aqueous recovery operation. (9/30/83)
CO-83-K-18 – View of a canyon in the cleanup phase. Canyons were processing rooms used to house plutonium handling operations that were not contained within glove boxes. Canyons were designed to become contaminated. (5/10/88)
CO-83-K-19 – View of the interior of Building 374. Building 374, attached to Building 371, became operational in 1978 as the new radioactive waste treatment facility, replacing Building 774. (6/26/79)
CO-83-K-20 – View of waste treatment control room in Building 374. The Building 371/374 Complex was designed to emphasize automatically controlled, remotely operated processes. (1/80)