B Reactor

Hanford B Reactor
U.S. National Register of Historic Places
U.S. National Historic Landmark
The face of B Reactor during construction.
Location:	Near junction of WA 24 & WA 240 on the Hanford Site
Nearest city:	Richland, Washington
Built/Founded:	June 7, 1943[1] to September 1944[2]
Architect:	E.I. DuPont de Nemours & Co.
Governing body:	U.S. Department of Energy
Added to NRHP:	April 3, 1992
Designated NHL:	August 19, 2008[3]
NRHP Reference#:	92000245

The B Reactor at the Hanford Site, near Richland, Washington, USA, was the first large scale nuclear reactor ever built. The project was commissioned to produce plutonium-239 by nuclear fission as part of the Manhattan Project, the United States nuclear weapons development program during World War II. It has been designated a U.S. National Historic Landmark since August 19, 2008.^[3][4]

Reactor design and construction

The reactor was designed and built by E. I. du Pont de Nemours and Company based on experimental designs tested by Enrico Fermi at the University of Chicago, and tests from the X-10 Graphite Reactor at Oak Ridge National Laboratory. It was designed to operate at 250 megawatts.

The reactor occupies a footprint of 46 by 38 ft (14 by 12 m) (about 1,750 sq ft (163 m²) and is 41 ft (12 m) (approximately five stories) tall, occupying a volume of 71,500 cu ft (2,020 m³).

The reactor core itself consisted of a 36-foot (11 m)-tall graphite box measuring 28 by 36 ft (8.5 by 11 m) occupying a volume of 1,000 cu ft (28 m³) and weighing 1,200 short tons (1,100 t). It was penetrated horizontally through its entire length by 2,004 aluminum tubes and vertically by channels for the "vertical safety rods," .^[4]

The core is surrounded by a thermal shield of cast iron 8 to 10 inches (20 to 25 cm) thick weighing 1,000 short tons (910 t). Masonite and steel plates enclose the thermal shield on its top and sides, forming a biological shield for radiation protection. The bottom of the thermal shield is supported by a 23-foot (7.0 m)-thick concrete pad topped by cast iron blocks.

The graphite composition was selected to moderate the nuclear reaction fueled by 200 short tons (180 t) of uranium slugs approximately 25 mm (1 in) diameter 70 mm (3 in) long (the approximate size of a roll of quarters^[4]), sealed in aluminum cans, and loaded into the aluminum tubes.^[4]

The reactor was water-cooled, with cooling water pumped from the Hanford Reach of the Columbia River through the aluminum tubes around the uranium slugs at the rate of 75,000 US gal (280,000 L) per minute. The water was discharged into settling basins, then returned to the river after allowing time for the decay of radioactive materials and the settling out of particulate matter.^[5]

Map of the Hanford site with the B/C reactor site shown at the upper left.

Reactor operation

The B Reactor had its first nuclear chain reaction in September, 1944, the D Reactor in December, 1944 and the F Reactor in February, 1945. The reactor produced plutonium-239 by irradiating uranium-238 with neutrons generated by the nuclear reaction. It was one of three reactors — along with the D and F reactors — built about six miles apart on the south bank of the Columbia River. Each reactor had its own auxiliary facilities that included a river pump house, large storage and settling basins, a filtration plant, large motor-driven pumps for delivering water to the face of the pile, and facilities for emergency cooling in case of a power failure.^[4]

Emergency shutdown of the reactor, referred to as a SCRAM, was attained either by rapidly fully inserting the vertical safety rods (now called control rods) or, as a backup method, by the injection of liquid boron into the reactor. The liquid boron system was later replaced by a Ball-3X system that injected nickel-plated carbon steel balls into the channels occupied by the vertical safety rods.^[4]

The plutonium for the nuclear bomb used in the Trinity test at Los Alamos in New Mexico and the Fat Man bomb dropped on Nagasaki, Japan was created in the B, D, and F reactors. These first three reactors ran for two decades, and were joined by additional reactors constructed later. The B Reactor was permanently shut down in February 1968.^[4]

Current status

B reactor as it appears in 2009.

B Reactor is now in "interim safe storage" status. The D and F reactors were shut down in June 1967 and June 1965, respectively. In a process called cocooning or entombment, the reactor buildings are demolished up to the 4 ft (1.2 m)-thick concrete shield around the reactor core. Any openings are sealed and a new roof is built. The D and F reactors have already been entombed, as have the C and DR reactors. Most auxiliary buildings at the first three reactors have been demolished, as well. The H, K-East and K-West reactors and the N-Reactor are scheduled to be entombed in that order.

The United States Department of Energy has administered the site since 1977 and offers public tours on set dates during the spring, summer, and fall of the year, as well as special tours for visiting officials. The B Reactor was added to the National Register of Historic Places (#92000245) on April 3, 1992, and was named a National Historic Landmark on August 19, 2008.^[3][4] It is in the process of conversion into a museum.

Sources

• Washington Closure Hanford - NewsletterPDF (666 KB)
• Hanford Site - Timeline 1943-1990PDF (168 KB)
• United States Department of Energy - B Reactor
• B Reactor a historic Landmark

References

External links

• B Reactor Museum Association A collection of Hanford-related documents from a group working to preserve the B-100 Reactor at Hanford.
• Reactor 105-B (museum) location: 46°37′49″N 119°38′51″W / 46.63028°N 119.6475°W / 46.63028; -119.6475Coordinates: 46°37′49″N 119°38′51″W / 46.63028°N 119.6475°W / 46.63028; -119.6475

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