Hanford: T Plant Virtual Tour

A long rectangular 2-story concrete building fills the frame and contrasts with the bright sun and blue sky. Several cars parked in front of the building.
T Plant was the first chemical separations plant built at Hanford.

NPS/BURGHART

 

Photos & Multimedia

Built during the Manhattan Project, Hanford’s T Plant was the first separations plant in the world constructed to chemically separate radioactive materials. Much of the separations work was done remotely to protect workers from the tremendous amount of radiation given off by the irradiated uranium fuel slugs. While humans had separated base and rare metals using heat and chemical processes for millennia, separating a man-made material from a highly radioactive fuel slug at an industrial scale had never been done before.   

Enjoy this virtual tour of the T Plant and learn about how Manhattan Project workers separated the plutonium, the product of interest, from the irradiated uranium. The T Plant is located on the secure Hanford Nuclear Reservation. In-person visitation is not authorized.  

Ways to Explore

Start the Tour: Begin the tour by selecting the play icon in the middle of the first image below. When the tour opens, click on the white circles to choose your path. Click on hotspots, the white “i” icons of your choice, to access informative text and images.

Audio Described Video Walkthrough: Watch the audio described video walkthrough tour by selecting the play icon in the middle of the second image.

Panoramic Tour: Explore a series of panoramic images and historic and modern photos of T Plant. 

Text and Image Descriptions: There are 24 hotspots in the virtual tour with text and photos. Below is the text and image descriptions for each of the virtual tour hotspots. Browse through all the hotspot titles or jump straight to a hotspot that interests you. 

 
 

Audio Described Video Walkthrough

 

Open Transcript 

Transcript

 

 

The T-plant building is a concrete box measuring 875 feet long, 65 feet wide, and 85 feet tall (267 by 20 by 25 meters). Along one side, three rectangular galleries, stacked on top of one another, run the entire length of the building.  

The Electrical Gallery sits at the base of the building, followed by the Pipe Gallery in the middle, and the Operating Gallery on top.  

Adjacent to and running alongside the three galleries is the canyon portion of the building. Composed of 40 individual concrete cells, it was here that the chemical separations process was carried out.  

Beginning at the eastern end of the Electrical Gallery, the long, narrow concrete corridor, approximately 18 feet wide by 10 feet tall (5.5 by 3 meters), stretches far into the distance, with unpainted walls and a dark grey painted floor. At the right, a black metal floor-standing cabinet houses original exhaust fan switch controls.  

Hanging from the ceiling, a single row of evenly spaced, industrial pendant lights with metal hoods runs the length of the gallery, alongside black metal electrical conduit, silver ductwork, and other smaller steel pipes. 

 

Moving forward down the gallery, several wide strips of yellow warning tape appear on the floor at the left, about four feet (1.2 meters) out from the left-hand wall. Words on the tape read: "Combustible Material Exclusion Zone."  

On the right-hand wall, original, black electrical panels hang alongside several grey, upgraded panels.  

Laid out on the floor in front of the panels, words inside two large squares of yellow warning tape read: "Keep this area clear." 

 

Continuing forward, on the floor at the left, yellow warning tape marks off another material exclusion zone.  

At the right, two tall, grey electrical panels stand out from the wall. Just beyond the panels at the right, a green Exit sign hangs above a doorway that leads to the 271-T Office Annex. 

 

Moving forward, yellow warning tape on the floor at the left marks off a material exclusion zone.   

On the right-hand wall, a large, black electrical box hangs beneath several parallel, horizontal rows of electrical conduit running the length of the gallery across the middle of the wall. To the right of the box, a four-foot (1.2 meter) square, recessed ventilation opening appears at the bottom of the wall. On the wall to the right of the opening, a white sign with red lettering and a red arrow pointing to the right reads: “Fire Barrier. Contact Fire Protection Engineering prior to drilling into Fire Barriers.” A second, smaller black electrical box hangs on the wall to the right of the sign, next to a grey metal exit door with a horizontal panic bar handle across the center.  

Yellow warning tape marks off large, square areas on the floor in front of both electrical boxes. A yellow sign inside each square reads: “Keep this area clear.” 

 

Continuing down the Electrical gallery, at the left, yellow warning tape marks off another material exclusion zone. To the right of this zone, a rectangular, grey metal box housing monitoring equipment stands on the floor beside a large tank for collecting and monitoring condensate.  

At the right, a green Exit sign hangs above a set of double, grey metal exit doors. To the left and right of the doors, several black and grey electrical boxes hang on the wall. On the floor in front of the boxes, additional yellow warning tape and signs mark off the areas to keep clear. 

 

Moving forward, at the left, two original, metal, crowbar-like tools designed and built for use in T-Plant activities hang on the wall, next to a couple grey, floor-standing electrical cabinets with glass panel fronts.  

At the right, a square, grey metal case houses monitoring equipment for the condensate collection system. It stands against the wall, next to two more large, cylindrical collection tanks. 

 

Continuing forward, posted on the left-hand wall is a radiation warning symbol: a yellow sign with a small, central red circle surrounded by three evenly spaced red blade sections like a propeller. A yellow warning sign beside it reads: "Work above 6 feet requires radiological control approval." A third yellow warning sign is placed over a floor vent, at the end of another material exclusion zone.  

At the right, an Exit sign hangs above a grey metal exit door. Flanking the door, several black electrical boxes hang on the wall, with “keep clear" spaces marked out on the floor in front. A Fire Barrier sign hangs on the wall to the right of the boxes. 

 

Moving further along, at the left, a collection of cardboard boxes sit stacked on wooden pallets.  

On the right-hand wall, a white sign posted on the bare concrete reads: “Electrical Gallery Section # 15,” beside a Fire Barrier sign with a red arrow pointing left. The numbers 15 and 14 are stenciled on the wall in red. 

 

Moving forward, the walls and ceiling are now painted white.  

On the right-hand wall, a Fire Barrier sign with a red arrow pointing left hangs beside the number 16, stenciled in red.  

At the left, yellow warning tape on the floor marks out another material exclusion zone. 

 

Moving to the end of the Electrical Gallery, at the right, a couple grey, floor-standing electrical boxes house upgraded switching gear. 

 

Ascending to the second floor Pipe Gallery, at the right, an office furniture and equipment storage area has been cordoned off with floor-to-ceiling chain link fencing with tall, blank panels behind.  

Along the left-hand wall, a fire extinguisher hangs next to a grey metal exit door. Just beyond the door, a white, cylindrical water heater stands on the floor. 

 

Moving forward, we face down another long, narrow concrete corridor with unpainted concrete walls and a dark grey, painted concrete floor. A single row of evenly spaced, industrial pendant lights runs the length of the gallery alongside black conduit, silver ductwork, and other smaller pipes.  

Turning around to the left, a large, recessed, square opening at the base of the concrete wall houses a ventilation fan. The stairs back down to the Electrical Gallery are behind us.  

Turning all the way around to face back forward, at the right, more floor-to-ceiling chain link fencing cordons off a restricted area. 

 

Moving forward, the fenced off area continues at the right, with the concrete wall of the canyon behind it. On the left-hand wall, a Fire Barrier sign hangs above a horizontal orange extension ladder hanging on the wall. Beyond the ladder, a yellow cabinet at the left contains flammable materials. Overhead, a label on a large silver pipe reads: "Abandoned Steam." 

 

Continuing forward down the gallery, at the left is another grey metal exit door. To the right of the door, the numbers 11 and 10 appear stenciled in red along the left-hand wall, next to another Fire Barrier sign.  

At the right, behind more chain link fencing, is a storage area for Personal Protective Equipment. Above the storage area, pink piping shows where original asbestos insulation has been remediated. 

 

Moving ahead, the numbers 10 and 9 appear stenciled in red on the left-hand wall. A fire extinguisher hangs on the wall under the number 10. A Fire Barrier sign hangs next to the number 9.  

The fenced off area continues at the right. 

 

Further along the Pipe Gallery, a radiation symbol appears on the left-hand wall. A yellow warning sign beside it reads: "Work above 6 feet (1.82 meters) requires radiological control approval." The numbers 9 and 8 appear stenciled in red on the left-hand wall. A Fire Barrier sign with a red arrow pointing left hangs beside the number 9. 

 

Continuing down the corridor, at the left, a white sign reads: "Pipe Gallery Section # 7." A tall metal cabinet stands on the floor beside a few spare fence sections.  

At the right, pipes of several different diameters run along the wall, secured with straps and hangers to evenly spaced, roughly six foot (1.82 meter) tall, narrow, iron rack supports mounted on the wall. A couple pipes are painted yellow, the others bare metal with splotches of green and yellow painted here and there. Additional pipes attach to and split off from those on the wall, rising overhead. Circular valve handles protrude from some of the pipes.  

On the floor in front of the pipes, stacks of cardboard boxes on wooden pallets stand beside another material exclusion zone on the floor. 

 

A little further on, a fire extinguisher hangs on the left-hand wall beside a large, recessed, square opening at the base of the wall with a ventilation fan.  

At the right, pipes continue along the wall, secured to more iron rack supports. Additional pipes attach to and split off from those on the wall, some with circular valve handles. Several lengths of small-diameter piping sit on the floor within a marked material exclusion zone. 

 

Continuing forward, the number 4 appears stenciled on the left-hand wall. A Fire Barrier sign hangs on the wall with a red arrow pointing left.  

Along the right-hand wall, original piping provided operators the means to introduce chemicals into the canyon cells.  

More metal parts and cardboard boxes sit on the floor behind yellow warning tape. 

 

Moving forward to the end of the Pipe Gallery, pipes of several different diameters continue along the right-hand wall. About halfway up the wall, two smaller pipes attach to one of the larger, yellow pipes, each with valves with circular handles. On the floor in front of the pipes, more cardboard boxes sit stacked on wooden pallets beside an additional material exclusion zone.  

Turning to the left, two metal cabinets with shelves stand side-by-side on the floor in front of the concrete wall. Spare parts for Pipe Gallery equipment are stored on these shelves.  

To the right of the cabinets, a Fire Barrier sign with a red arrow pointing left hangs on the wall, in front of a grey metal exit door with an Exit sign above it. 

 

Continuing forward, we ascend to the Operating Gallery and face down a third long, brightly lit concrete corridor with white walls and a dark grey, painted floor. Evenly spaced, rectangular fluorescent light fixtures hang from the ceiling. Additional pipes run along the ceiling alongside silver ductwork. High on the right-hand wall, a metal wiring tray runs the length of gallery.  

Turning to the right, a series of pneumatic valves along the base of the concrete wall stand covered behind wood and Plexiglas cabinetry. Posted radiation symbols identify this as a potential contamination area. To the right of the valves, a set of tall, green metal panels house gauges and chart recording devices used to monitor conditions within the canyon cells.  

Continuing clockwise around the gallery to the opposite wall, an Exit sign hangs above a grey metal exit door. A Fire Barrier sign with a red arrow pointing left hangs beside a second sign that reads: "Operating Gallery Section # 15.” Two smaller, black and yellow signs on the wall below identify sections 15 and 14, above an orange ladder hanging sideways on the wall.  

To the right of the ladder, two grey electrical boxes hang on the wall, with “keep clear” areas marked off in front. A three-dimensional scale model of T-plant sits on a table to the right of the boxes. 

 

Moving further down the Operating Gallery, at the base of the right-hand wall, a series of grey, rectangular wooden boxes, each about four feet long by three feet wide by two feet tall (1.2 by 1 by point-six meters) cover pipe penetrations along the floor.  

Turning to the right, a large blue vacuum pump sits on the floor beside several black-and-white posters displaying photographs and descriptions of T-plant operations. The three-dimensional scale model of T-plant sits opposite these posters.  

Turning back to the left, a Fire Barrier sign hangs on the left-hand wall beside a grey metal exit door with an Exit sign above it. 

 

Continuing forward, on the left-hand wall, small black and yellow signs indicate sections 12 and 11, flanked by a couple tall, floor-standing, padlocked metal storage cabinets.  

Along the opposite wall at the right, six four-drawer, metal filing cabinets stand beneath a radiation symbol and additional yellow warning sign, next to a few more grey, rectangular box covers. 

 

Further along the gallery, at the left stands a tall, blue metal cabinet with nearly a dozen wide, sliding metal drawers of different heights. Ductwork, pipes, and the wiring rack continue along the ceiling.  

At the right, more low, rectangular, grey box covers stand along the base of the wall. 

 

Continuing forward, mounted to the right-hand wall, an aluminum rack supports two newer, grey electrical boxes with four buttons each on the front. Just beyond the rack, cardboard boxes of supplies sit on wooden pallets, beside a few more low, rectangular, grey box covers along the base of the right-hand wall. A couple pipes with circular valve handles protrude through the top of one of the boxes, beside a third pipe with a green label printed with the word, “Drain.”  

Turning to the left-hand wall, two black and yellow signs indicate sections 9 and 8, beside a large, vertical, silver metal pipe that rises from a metal floor grate. A label on the pipe reads, “Med-Pressure Steam,” with a black arrow pointing up. To the left of the pipe, another Fire Barrier sign with a red arrow pointing left hangs on the wall. To the right of the section numbers, a white paper directory hangs above a telephone mounted to the wall. A fire extinguisher hangs on the wall a little further along at the left. 

 

Moving down the corridor, several more low, grey boxes along the base of the right-hand wall cover pipe penetrations through the floor. Three pipes stick out of the top of one of the boxes. In front of an electrical panel at the right, yellow warning tape on the floor marks off a "Keep Clear" area.  

On the opposite wall at the left, two yellow signs indicate the location of canyon sections 7 and 6, next to a Fire Barrier sign with a red arrow pointing to the left. At the base of the wall, a series of grates appear along the floor. 

 

Near the end of the Operating Gallery, at the front left, an Exit sign hangs above a grey metal exit door, next to a fire extinguisher.  

At the front right, a series of tall, grey panels house original equipment used to monitor canyon activities. Closer at the right, more supplies sit on wooden pallets beside yellow warning tape on the floor that marks off a "Keep Clear" area in front of a few modern wall-mounted electrical boxes.  

On the opposite wall at the left, a posted sign reads: "Operating Gallery Section # 6.” Two smaller yellow signs identify canyon sections 6 and 5. 

 

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Duration:
14 minutes, 51 seconds

An audio described walkthrough of T Plant in Hanford, Washington.

 

Hotspot Text & Photo Descriptions

There are 24 hotspots in the virtual tour with text and photos. Below is the text and image descriptions for each of the virtual tour hotspots. Browse through all the hotspot titles or jump straight to a hotspot that interests you. 

Built during the Manhattan Project, Hanford’s T Plant was the first separations plant in the world constructed to chemically separate radioactive materials. Much of the separations work was done remotely to protect workers from the tremendous amount of radiation given off by the irradiated uranium fuel slugs. While humans had separated base and rare metals using heat and chemical processes for millennia, separating a man-made material from a highly radioactive fuel slug at an industrial scale had never been done before.

T Plant was designed to chemically separate about a half-pound (250 g) of plutonium metal from one ton (907 kg) of irradiated uranium each day. That is like separating the weight of a hamster from a mass that weighed as much as an average automobile! The chemical separations process that enabled Manhattan Project personnel to recover miniscule amounts of plutonium from the irradiated uranium were developed by University of California chemist Glenn Seaborg. His original experiments were conducted with micrograms of plutonium. T Plant’s separations processes used a billion times the amount of chemicals that Seaborg used in the lab.

A black and white aerial photo of a large rectangular building on a flat plain. Several smaller outbuildings, a smokestack, and a water tower run along the left-hand side of the rectangular building.

Hanford’s role in the Manhattan Project was to produce plutonium on an industrial scale to be used in the world’s first atomic weapons. This story begins at the Shinkolobwe mine (pictured) in present-day Democratic Republic of the Congo, known as the Belgian Congo during World War II. Miners extracted some of the world’s richest uranium ore from this mine and shipped it to Canada for refining. After refining, the ore arrived at one of several plants in the United States that processed the uranium ore into pure uranium metal and shaped the uranium into billets.

Workers loaded the billets onto railcars and shipped the billets to Hanford where they arrived at the fuel fabrication site, also known as the 300 Area. Here, machines milled the uranium billets into cylinders and sealed the uranium cylinders in aluminum jackets creating fuel slugs for the nuclear reactors. 

Workers drove the fuel slugs across the Hanford Site to the B Reactor and its two siblings, D and F reactors, for irradiation. After irradiation in a nuclear reactor, workers carefully loaded the highly radioactive fuel slugs into shielded, water-filled casks on train cars for transportation to the T Plant.   

At T Plant, the fuel went through a series of complex chemical processes to separate plutonium from uranium and other radioactive byproducts. Scientists in Los Alamos, New Mexico, assembled the core of the Trinity Test device and the Fat Man atomic bomb using Hanford’s plutonium. The chemical separation process created millions of gallons of toxic waste that is stored in underground tanks. Safe management and disposal of this waste is the biggest challenge at Hanford today.

A black and white photo of a carved out mine pit. A man in a hat leans on the right hand side of the mine wall.

Engineering a building for safe chemical separation of plutonium required an enormous structure. T Plant is 875 feet (266.7 m) long, which is the length of almost three American football fields. It is referred to as the “canyon.” T Plant also earned the nickname “Queen Mary” since it is long and narrow like the well-known ocean liner, and much of the building is located below ground. 

The T Plant building is a concrete box measuring 875 feet (266.7 m) long, 65 feet (19.8 m) wide, and 85 (26 m) feet tall. Along one side, there are three rectangular galleries: electrical gallery, pipe gallery, and the operations gallery. These galleries are stacked on top of one another and run the entire length of the building. Adjacent to and running alongside the three galleries is the canyon portion of the building, composed of 40 individual concrete cells. The chemical separations process took place in the canyon portion of the building.  This huge fortress of a building required a lot of building materials:

  • 1,880 tons (1705 mt) of reinforcing steel, which equates to about 10% of the steel used to build the Eifel Tower.

  • 27,000 square feet (3,000 sq m) of reinforcing mesh, which is enough mesh to cover every square foot of an American football field.                                             

  • 90,473 cubic yards (69,172 m3) of concrete, which is enough concrete to build a two-lane road from Seattle, Washington to Salt Lake City, Utah.

  • 59,500 square feet (6,000 sq m) of roofing material, which is enough to cover nearly three American football fields.

A black and white aerial photo of a large rectangular building on a desert plain. Several small outbuildings and a smokestack appear below the large building. The measurements 65, 875, and 85 appear superimposed along the large building in green font with a yellow line running between the numbers.

The picture above is a view of the west end of T Plant under construction. Note the thick concrete walls that protected workers from the intense radiation given off by the irradiated fuel slugs processed in the building. In the lower left is the electrical gallery, which is underground. Stacked on top of the electrical gallery is the pipe gallery. On top of the pipe gallery is the operating gallery. The space in the upper left is the “crane way” for a massive 75-ton (68 mt) capacity crane that was suspended over the canyon. The crane cab traveled the length of the building using the crane way with the actual crane sitting atop the large space in the right portion of the photo. T Plant also has an office complex and facilities where workers mixed the chemical used in the separations process.

A black and white photo of a large rectangular building under construction. Several vehicles, equipment, and scaffolding appear at the near end of the building.

The tremendous amount of radiation given off by the irradiated uranium fuel slugs required protecting workers with up to 9 feet (2.74 m) of concrete shielding between them and the equipment. These extreme conditions pushed engineers to create a chemical separations building that had never been built before—an amazing feat accomplished in about 18 months.The timeline for construction of T Plant:

01-16-1943       General Leslie Groves approves the site selection for the Hanford Engineer Works (HEW) in eastern Washington state
02-08-1943       Directive by the U.S. Secretary of War authorizing acquisition of land for Hanford
03-22-1943       DuPont officially starts construction activities at Hanford
06-08-1943       DuPont chooses the bismuth phosphate method for the separations process
06-26-1943       Construction begins on T Plant
09-22-1944       Construction department turns over T Plant to the Operations Department
09-26-1944       Startup of the B Reactor, plutonium production at Hanford begins
10-09-1944       Construction crews leave T Plant and testing for operations begin
12-26-1944       The first production batch of hot fuel slugs is processed at T Plant
02-05-1945       First shipment of plutonium leaves Hanford for Los Alamos

A black and white photo of a sandy dugout hole. Pipes cranes, and various other construction equipment surround the hole.

Hanford was the first industrial-scale plutonium factory in the world, and for safety reasons, it was situated in a remote area of eastern Washington and isolated from major cities and highways. Workers recruited from more populated areas of the country often felt in the middle of nowhere and were struck with an immediate case of homesickness after arriving at the Hanford Site.

One of the biggest challenges managers faced was finding and keeping workers. Finding tens of thousands of skilled and unskilled workers was a feat. A high rate of turnover among the workforce compounded this problem. Throughout the life of the project, DuPont conducted more than a million interviews in 47 states, resulting in 90,500 hires, of which 72,500 employees actually showed up for work. The above image shows several of the Hanford construction working building operating gallery.

Due to extensive aircraft and ship building that was taking place on the West Coast, the shortage of skilled labor required DuPont to provide specialized training and transfer many craftsmen from other DuPont plants and projects.

A black and white photo of a long, narrow hallway with light fixtures in a row along the ceiling, wooden planks along the floor, and pallets of lumber along the right side of the hallway.

Research and experimentation to develop the chemical process to separate plutonium from irradiated uranium was carried out at University of Chicago’s Met Lab (pictured) and the Clinton Engineer Works in Tennessee. Several suggested methods for the separation of the plutonium from the uranium were evaluated. The bismuth phosphate process was selected based on simplicity and use of less volatile chemicals in the process.

The bismuth phosphate process involved multiple steps:
1. Remove aluminum cladding from the irradiated uranium fuel slugs by dumping the slugs into a dissolver and covering them with a basic caustic such as sodium hydroxide or sodium nitrate solution. The solution was then brought to a boil.
2.  The next step was the slow addition of sodium hydroxide to the solution to remove the liquified aluminum from the waste stream and bonding agents that enclosed the slugs.
3.  Next the slugs were washed with nitric acid to dissolve the irradiated uranium. Bismuth nitrate and phosphoric acid were then added to separate the plutonium from the uranium and the mixed fission products.
4. Following removal of the uranium and mixed fission products, the solution ran through a centrifuge to separate out the heavier plutonium material from the lighter mixed fission products, namely cesium and strontium. In the process nearly 90 percent of the gamma radiation was removed from the remaining plutonium material. The resulting product was a plutonium-containing paste that was dissolved in nitric acid.
5. The plutonium paste was then further reduced by repeating the previous steps and using additional chemicals. The result was a plutonium nitrate solution with a higher concentration of plutonium. This material was then transferred to the 224-T building where it was further purified and reduced. At this stage, the radioactivity was reduced to the point where it could be handled without heavy shielding.  It was then delivered to the 231-Z building for final processing before being shipped to Los Alamos to be incorporated into atomic weapons.

A black and white photo of a laboratory setting. Several counters, drawers, desks, and chairs appear in the image. Lamps line the desks and light fixtures appear on the ceiling.

We just passed through the electrical gallery (pictured). The electrical gallery is the lowest level of the manned portions of the processing building. This gallery runs the length of the building adjacent to the canyon and contains all electrical circuitry for the operation of the building. Since T Plant has been in continuous operation since 1944, much of the electrical circuitry has been upgraded, as is obvious by the newer electrical panels you see in the virtual tour. Many of the original panels are still in use today.

A black and white photo of a long, narrow hallway. A dark piece of equipment appears along the left-hand wall in the foreground with several more evenly spaced in the distance. Pipes and light fixtures hang from the ceiling.

We are now in the pipe gallery (pictured). The steam, water, and various chemicals that were used in the separations process were brought into T Plant through the pipe gallery. No special shielding or procedures were required for normal operation in the pipe gallery because radioactive solutions did not pass through the pipe gallery. Radioactive materials were all contained in the canyon side of the building.  

A black and white photo of a long narrow hallway. Several pipes appear along the walls and ceiling, with light fixtures hanging from the ceiling.

T Plant was the first industrial scale building designed to separate highly radioactive materials. Protecting workers was the upmost concern when designing the facility and implementing operations. Herbert Parker (pictured), a prominent medical physicist, established the Health Instruments Section and initiated a radiological monitoring and control program at Hanford, the first program of its kind. His goal was to develop formal procedures and controls for the protection of workers, citizens, and the environment from excessive radiation exposure. His innovations led to a better understanding of the effects of radiation on human health, enhanced protections for workers, and the emergence of a field that continued to protect lives long after the Manhattan Project ended.

Herbert Parker created administrative and engineered controls to protect workers from radiation exposure. Engineered controls included shielding, locked access doors, and long handles for equipment. Administrative controls such as documented work procedures, well-defined zones, and special badges to monitor worker exposure to radiation were also implemented.

Gamma, beta, alpha, and neutron radiation pose different risks to workers, and workers at Hanford had to contend with all the different types of radiation. Depending on theradiation type emitted from a source, workers use a specific recipe of time, distance, andshielding to protect themselves. Alpha radiation cannot penetrate a piece of paper. Even the outer layer of our skin can stop it, but alpha radiation is very dangerous inside the body.

Gamma radiation is the most penetrating form of radiation and is the greatest concern externally. Thick shielding such as six or more feet of concrete or more than a foot of lead is required to stop gamma radiation.

A black and white photo of three men standing in suits. The man on the left is using a pointer to show a posterboard to the two men standing at right. A chalkboard appears in the background.

Protecting people and other living things from a source of radioactivity is not unlike protecting them from a source of high heat or even sound. Different types of materials provide different levels of protection. For example, a 10-fold reduction in gamma radiation can be made with any one of the following: about 1.7 inches (4 cm) of lead, 8.5 inches (21.5 cm) of concrete, 8 inches (20 cm) of aluminum, or 20 inches (50 cm) of water. It takes about 1,300 feet (40 m) of air to provide the same shielding as the above-described materials provide.

The design of the T Plant included barriers to protect workers from radiation. Thick concrete walls and concrete cover blocks (pictured are cover blocks under construction) are two examples of engineered barriers deployed to protect workers from the high levels of radiation within the canyon. The walls ranged in thickness from 5 feet (1.52 m) to 9 feet (2.74 m).

There are 40 cells within the canyon. A typical cell was covered by four cover blocks: three C1 blocks that weighed about 32 tons (29 mt) each, and a single C2 block that weighed about 26 tons (24 mt) and served as the keystone block. The C1 block measured 6 feet (1.82 m) and 4.75 inches (12 cm) wide by 15 feet (4.57 m) and 11.5 inches (29.21 cm) long and was 6 feet (1.82 m) thick. The C2 block was 5 feet (1.52 m) and 10.5 inches (26.67 cm) wide but otherwise the same as a C1 block. There were 328 cover blocks used in the T Plant.

A black and white photo of a long row of construction equipment, including large boxes, a rail cart on a track, and several cranes.

During the design of the separations building a major concern was the level of radiation that workers could be exposed to during separations activities. To reduce this hazard the canyon was designed to be operated remotely. To accomplish that task, it was necessary to design and build equipment that could operate without direct hands-on manipulation by individuals. The result was a crane with multiple hooks and multiple capacities and equipment that could be operated using air or electrical connections such as impact wrenches and piping equipment that had impact wrench connections to open and close the valves.

The crane spanned 58 feet (17.67 m) across the canyon (pictured). The bridge, the side-to-side transport that carried the hooks for lifting equipment, across the canyon’s width, had a range of 32 feet (9.75 m), covering the working area of the canyon. The canyon is to your right as you move through the electrical gallery. There were multiple lifting hooks and hoists available that provided the crane operator with the ability to raise the cover blocks, lift equipment into and out of each cell, and remotely add and remove liquid and electrical jumpers in the cell.

Protecting workers in the crane from the radiation in the gallery was critical. The first line of shielding for the cab (and its occupants) was the cabway in which the crane rode. The cabway was 5 feet (1.52 m) thick concrete wall that separated the galleries from the canyon and ran the length of the building. This put the cab in a three-sided channel, surrounded by heavy concrete walls on both sides and below. The roof and upper walls of the crane were 4.5 inches (11.43 m) thick. The lower walls were 3 inches (7.62) thick, and the crane floor was 1.5 inches (3.81 cm) thick.

 

A black and white photo of a long, tall, wide hallway, with lit scaffolding along the ceiling. Two men observe an elevated pulley system pulling equipment down the hallway.

Irradiated fuel slugs were transported from the B Reactor to the T Plant by rail car in water-filed and shielded cask cars (pictured). When the train arrived at T Plant, the cask car would be backed into the train tunnel at the east (head) end of T Plant through a roll up door. If you were to continue the direction you are going, you would eventually encounter the railroad tunnel. The railroad personnel and the operations staff would disconnect the cask car from the train engine, evacuate the tunnel area, and then close the roll up door. Once all was clear, the crane operator removed the cover blocks from cell 3. Then the operator would position the crane above the cask car and use the crane hooks to remove the transport basket from the cask car and move the basket with the fuel slugs to cell 3 where and dump the fuel into one of the dissolvers in the cell to begin the separations process. Once the fuel slugs were dumped into the dissolver, the crane operator would replace the cover blocks for the cell.

The operations staff in the operating gallery would start the first step in the plutonium removal process by dissolving the aluminum cladding on the outside of the fuel elements. All of this was done remotely with the cover blocks in place to reduce the tremendous amount of radiation being released at this point in the process.

 

A black and white photo of a flatbed railroad car at left and a locomotive at right with a railroad crossing sign between the two cars in the foreground. A man in white stands on a walkway on the locomotive.

DuPont used two types of optical devices for the crane operator to “see” inside the canyon: a periscope mounted on the crane bridge to see the canyon deck and a television camera mounted on a crane hook that focused on the crane hooks. These devices provided a broad field of view in the canyon, as well as a closeup view of the cell equipment and crane hook or impact wrench. The remote television CCV that was used on the T Plant crane represents one of the earliest uses of television in an industrial setting.Learning how to use the crane and its optics to remotely work in the canyon required a bit of a learning curve.

The following is from an oral history describing this process:
So, I got two or three of the top operators into the cab, of course there was no radiation yet, and I said, “Gentlemen, I’m not a cane operator. You are. I think we have to get together and learn how to use what we’ve got.” Oh, they thought that would be terrible. The first thing you know they were getting the biggest kick out of looking through the periscope, with this great big hook going down and hooking on to a wheelbarrow or something down there in the cell area, picking it up and gently putting it down. They had a ball. They were fantastic. The crane operators learned in 10 hours or so.

A black and white photo of a man with grey hair in a suit sitting at a desk. The desk is covered with knobs and levers.

Administrative and engineering controls use time, distance, and shielding to protect workers from radiation exposure. Managing or limiting the amount of time workers are exposed to a radiation source is an example of administrative control and is one of the easiest controls to manage. 

The above photo shows a recording of exposure for a particular task. During the early startup periods at Hanford the exposures were based on a 40-hour week, with limits for exposure for a week, a month, and a year. Timekeeping was a minimum of a two-person task. The primary individual was the “radiation monitor” who continually performed the task of evaluating radiation exposure to the worker.  The second individual involved was typically an operation staff member who recorded the radiation levels provided by the monitor. Workers were limited to 300 mRem radiation dose per week to keep employees below the annual exposure limit of 5 Rem. If an employee worked on a high exposure job during the week, he was then limited to the amount of exposure he could receive for the remainder of the recording time frame.

A black and white photo of two hands on top of a timesheet card. The right hand is holding a pencil to fill out a row on the card.

Misadventures with radium and X-rays in the early 20th century, some deadly, provided a starting point for dealing with the new problem of radiation in an industrial workplace like the T Plant.

Herbert Parker reviewed the recommendations of the 1934 National Committee on X-Ray andRadium Protection and introduced controls for working with radiation in 1944, including theSpecial Work Permit (SWP).

An SWP is a standardized list that instructs employees on how to conduct a specific task ina radiological zone. A health physicist developed an SWP for the task and workers reviewed them prior to starting the assignment, typically during a pre-job planning meeting. This form of standardized procedure became the basis of many of the nuclear safety protocols still used today. These instructions included the task to be performed, the appropriate protective devices to be worn including clothing, respiratory requirements, training requirements for the workers, special equipment needed, estimates of exposures, time keeping requirements, and necessary approvals to perform the work.

A black and white photo of a man in white coveralls and a white hat. He is using both hands to reach for a pen in his left breast pocket. An ID badge hangs from the pocket.

As the distance from a radioactive source increases (i.e., move farther away from the source), the measured dose drops off rather quickly, inversely proportional to the square of the distance from the source. In other words, if the radiation measures X at 1 foot (.30 m) from the source, at 5 feet (1.5 m) it would measure only 1/25 or 4 percent of the original dose.

Putting distance between people and the source of radiation can be a simple procedure. In the case of the levels of radiation handled at T Plant, just maintaining a safe distance as the only control would have made the operation of the plant virtually impossible because the “safe” distance from a batch of irradiated slugs would have been measured not in feet, but in miles. In fact, the distances between the separations plants, reactors, and the public were, indeed, measured in miles, so that an accident at one plant might not force the abandonment of the others.

A black and white aerial photo of a large industrial complex on a flat desert plain. Several dozen buildings and a tall smokestack can be seen.

The canyon within T Plant was designed with remote handling as an integral part of its design. This provided for the elimination of direct hands-on activities to install, remove, or adjust the flow of material from one cell to the next. This was accomplished by the development of what is called a “jumper,” which is a piece of pipe shaped for a particular purpose that can be installed and connected by an air operated impact wrench suspended from the crane by the crane operator about 40 feet (12 m) away in a shielded crane cab.  Additionally, all pipe penetrations through the walls of the cells and into the galleries were installed as shown in the above photo with a “bend” in the pipe to prevent radiation passing through the pipe to the operations staff on the other side of the wall. Radiation travels in straight lines; therefore, the bend in the pipe would not allow radiation to travel through the pipe.

A black and white photo of several dozen large wires coming out of a left-hand wall and sloping downward to the right of the photo.

We are now in the operations gallery (pictured). Here operators remotely monitored and control the separations process in the canyon as there are no openings between the galleries and the canyon.  The T Plant operations crew was made up of several disciplines.

  • A radiation monitor measured radiation levels and conducted surveys for radioactive contamination in the T Plant.

  • The nuclear/chemical operator manipulated the chemical batch processes for separations of the plutonium and operations of all supporting equipment (e.g., pumps, dissolvers, centrifuges, and other canyon equipment).

  • The vent and balance operator was responsible for maintaining heat and cooling for the buildings and control of ventilation airflow.

  • The shift engineer provided technical support to the operations staff.

  • The shift manager was responsible for the overall operation of the facility.

  • A craft person (e.g., carpenter, sheet metal worker, iron worker, pipe fitter, painter) to make repairs as needed.

  • A janitorial crew for housekeeping duties. 

In the photo above, two nuclear/chemical operators monitor process gauges for work that is being conducted within the cells in the canyon. One of the operators controls a valve for introduction of additional materials into the process stream.

A black and white photo of a man in a hat seated on a tall chair on the left-hand side of a long hallway. The walls at left and right are covered with dials and meters. The man in using his left arm and hand to adjust a dial on the left-hand wall.

Gardner C. Blackburn worked as a carpenter foreman in the T Plant starting in 1943. He described a typical workday in the T Plant:

We were going all the time with several batches; once we got one going, another one would be right behind it. I had an operator on each of the boards (one for each section). Before there was any movement of the process materials from one tank to another, I had to go unlock the board. The steam went to them for jetting, and then the air blew them out to cool them off, and then we locked them up again. So I had a lot of walking up and down the gallery.I had a supervisor who sat in the office most of the time. Of course, he would talk to the operators, but I did all the running on my shift (there were four shifts and four of us chief operators). I had the keys and had to write in the book at the end of a shift; we always had a log, and I was responsible for filling it out. The pages in the log told the operators just how long to settle, how much and what type of chemical to put in. And then the operator had to put in that he did this, and he did that, and he did this. That’s the way we ran it.  
Gardner C. Blackburn, 17-Nov-1999

A black and white photo of a man sitting in a tall chair on the right wall as another man stands directly behind him. The walls in the long hallway are covered in dials, meters, and equipment. The seated man is adjusting a dial with his right arm and hand.

The canyon was normally unoccupied but needed a constant flow of air to exhaust the radioactive fumes from the separations process going on in the cells. Air flowed into the canyon through 11 filtering and washing units in the outside wall above the crane cabway. The air circulated throughout the canyon and into the cells through slots in their concrete covers. The air then moved into the canyon’s main ventilation exhaust tunnel that ran the entire length of the building. The air finally exited the building through the 291-T exhaust stack. Airflow was always maintained from lowest potential for contamination to highest potential to keep the air as clean as possible where most workers performed their tasks.

Sampling for releases of radioactive material began even before the plant went online. The photos above shows a “smoke testing” events prior to processing activities in T Plant for the purposes of determining the distribution of gaseous and particulate material that might be released from the 200-foot (60.96 m) exhaust stack during separations processing.

During the early operation of T Plant and other separations buildings, it was easy to determine if the plant was operating as you approached your work area. One witness to the first step, dissolving the irradiated fuel slugs in nitric acid, said, “Brown fumes blossomed above the concrete canyons, climbed thousands of feet into the air, and drifted sideways as they cooled.” A typical sight at T Plant during operations.

A black and white photo of a flat desert plain with a large rectangular building in the far background. A smokestack with smoke rising from it is seen in the vicinity of the building.

On December 2, 1949, the Atomic Energy Commission and the United States Air Force conducted an experiment known as “Green Run” at the T Plant. It was the largest single release of radioactive iodine-131 in Hanford’s history, covering vegetation as far north as Kettle Falls, WA and as far south as Klamath Falls, OR.

During the Cold War, plutonium production at Hanford increased dramatically, as did the production in the Soviet Union as they conducted atomic bomb testing in August 1949.  The United States feared that the Soviet Union would build a nuclear arsenal, thus, they needed a way to monitor Soviet nuclear weapons production.

U.S. Government officials, hoping to develop better methods for detecting Soviet nuclear weapons production, initiated what is known as the Green Run. Its purpose was to test by tracking and measuring a large volume of particles released into the air at Hanford. In the experiment, fission products from Hanford’s reactors were processed after only 16 days of cooling, rather than the normal 90 to 125 days, to replicate the Soviets’ process. This “green,” highly radioactive fuel was then processed, intentionally releasing high quantities of iodine-131 and other radioactive gases, unfiltered, from Hanford’s Chemical Separations “T Plant."

Key to the success of the Green Run was favorable weather. The Health Instrument Division of the General Electric Company established five conditions that had to be met. First was a layer of cold air close to the ground. The Division believed that this inversion would protect the ground from stack emissions. There also could not be any precipitation that would hinder measurements from the air. Wind speeds above 200 feet (60.96 m) had to be less than 15 miles per hour (24.14 kph) and come from the west or southwest. Lastly, all conditions had to remain stable long enough for the emissions to be measured.

From the outset, the experiment did not go as planned. Scientists predicted that 4,000 curies of iodine would be released. Analysis after the experiment proved that roughly twice the predicted amount was emitted. Wind directions on the test day went mainly northwest to southeast which dispersed the radioactive material around the state of Washington. Radioactive iodine ended up on the ground in vegetation and water. Vegetation contamination readings by Hanford’s environmental monitoring staff showed 600 times the tolerable amount in Kennewick, WA. Adverse weather on the day of the test doomed its success. Rain caused significant concentrations of radioactive material to fall on Spokane, WA and Walla Walla, WA.

Winds throughout the experiment’s run changed direction and scientists lost track of the radioactive release. The map above shows the of dispesion of materials from the Green Run.

The amount of iodine-131 released during the Green Run is estimated to be around 8,000 curies. Compare this to the approximately 15 curies of radiation released from the Three Mile Island accident in Pennsylvania in 1979. The people affected from the Green Run and other radiation releases due to accidents or negligence are known as the Downwinders. The Green Run experiment resulted in long-term health problems for many of the Downwinders, such as increased cancer rates and lymphatic illnesses.

A tri-color map (three shades of lavender) showing Washington and Oregon. Several quasi-circular outlines appear on the map radiating from the Hanford Site and getting larger the farther away they move.

At the conclusion of the process in the T Plant canyon, the material was piped to a nearby building, named 224-T, for further concentrating.  The fuel was originally processed in “batches” to limit the possibility of a buildup of plutonium and the possibility of a chain reaction (nuclear criticality). The “batch” of irradiated fuel from the reactors had now been reduced to about 325 gallons (1230 l) of plutonium baring solution. The separations process also removed much of the mixed fission product waste from the solution, which significantly reduced the radiation levels.  This solution was then further processed to remove additional waste materials and reduce the volume to about 8 gallons (30.28 l) of plutonium concentrated solution.

The product solution from the 224-T building was stored in a special container and transported to the 231-Z building (pictured) by motor vehicle. At this stage of the process, the radioactivity of the solution was only a small consideration. Of greater concern was the product itself, plutonium, which is quite deadly when inhaled or absorbed through the skin. The plutonium was pulled from the solution in the form of plutonium nitrate, which was reduced in volume by evaporation, transferred to a special container for shipment, and then evaporated still more until it was thick and paste-like material.

On February 5, 1945, first small batch of plutonium nitrate was ready for shipment to the Manhattan Project laboratory in Los Alamos, New Mexico where the plutonium was fabricated into the core of atomic weapons.

A black and white photo of counter space on the left with pipes, wires, and equipment running from the countertop and up the left wall.

Once the plutonium was extracted, the chemically separated uranium, unwanted radionuclides, and chemicals used to dissolve the fuel slugs became liquid waste and was put into underground waste storage tanks at Hanford. The system for handling wastes from the separations process at T Plant was never meant to be a long-term solution. The scientists and engineers who designed the Hanford plant were aware of the waste disposal problem. Given the burdens and limitations brought on by the war, they were not able to address the problem other than in the short-term. Therefore, the issues associated with waste were kicked down the road to a later time.

The ventilation system and stack removed noxious gases from the cells and canyon, diluted them, and dispersed them into the atmosphere. The removal of liquid wastes from the chemical separations process was handled by the 241-T tank farm, a system of large-scale storage tanks, and drainage fields. At the heart of the tank farm were 12 large storage tanks each was 75 feet (22.86 m) in diameter and could hold about 530,000 gallons (2,006,268 l) with a depth of 16 feet (4.87 m). They were constructed underground of concrete with a welded steel liner and buried under 9 feet (2.74 m) of earth for shielding.

Each series of three tanks were linked together in a cascade, so that as the first tank filled, it would spill into the second tank, which would eventually spill into the third tank. Liquid waste coming to the tank farm could be sent to one group of tanks or another by means of diversion boxes.

Today the waste legacy left by the Manhattan Project and the Cold War plutonium production is about 56,000,000 gallons (211,983,060 l) of highly radioactive liquid waste that in many cases has been stored for nearly 80 years and continues to be managed by the Hanford contractors under contract with the Department of Energy.

Plutonium produced at Hanford was in the Trinity test on July 16, 1945, and in the Fat Man atomic bomb dropped on Nagasaki, Japan, on August 9, 1945. T plant continued operating as a Cold War facility and is still in operation. Its current mission is radioactive sludge storage.

Learn more about the Manhattan Project and its many legacies: www.nps.gov/mapr

A black and white aerial photo of 12 large circular structures in the flat desert. Several small structures are scattered throughout the landscape.

Last updated: February 15, 2024

Contact Info

Mailing Address:

Manhattan Project National Historical Park
c/o NPS Intermountain Regional Office
P.O. Box 25287
Denver, CO 80225-0287

Phone:

Hanford: 509.376.1647
Los Alamos: 505.661.6277
Oak Ridge: 865.482.1942

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