Hanford B Reactor
First industrial-scale nuclear reactor in Richland, Washington. Built 1944. Added to the National Register in 1992, and a National Historic Landmark.
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What it is
The B Reactor at the Hanford Site, near Richland, Washington, was the first large-scale nuclear reactor ever built, at 250 MW. It achieved criticality on September 26, 1944. This reactor was of vital importance to the Manhattan Project, the United States nuclear weapons development program during World War II. Its purpose was to convert part of its natural uranium fuel into plutonium-239 by neutron activation, for use in nuclear weapons. Pure plutonium was then chemically separated at the site's T Plant, as an alternative to the Project's uranium enrichment plants in Tennessee. The B reactor was graphite moderated and water-cooled, via a contaminating open cycle with the Columbia River.
Text from Wikipedia, CC BY-SA 4.0.
The record
| Property type | Structure |
| Address | Near jct. of WA 24 and WA 240, Hanford Site, Richland vicinity, WA |
| County | Benton County |
| Listed | Apr 3, 1992 |
| Listed for | Military, Engineering, Science, Politics and government |
| Level of significance | National |
| Reference number | 92000245 |
| Built | 1944 · more from the 1940s |
| Type of place | nuclear reactor |
| Designations | National Historic Landmark, Historic Civil Engineering Landmark |
| Contributing resources | 1 structure |
| Standing | Yes |
The nomination form, the document that argues why this place matters, is in the National Archives: Read the nomination ↗
Visiting
| Address | Near jct. of WA 24 and WA 240, Hanford Site, Richland, WA |
| Coordinates | 46.6303° N, 119.6473° W · Directions ↗ |
| Nearest national park unit | Ice Age Floods National Geologic Trail · 31 miles · on Park Atlas |
Explore
Map
Nearby in Benton County
Public land around it
| Saddle Mountain National Wildlife Refuge ↗National Wildlife Refuge, U.S. Fish and Wildlife Service | About 2 miles away162,461 acres |
Wilderness Atlas publishes a centroid and an acreage for each unit, not a boundary line. Distance here is measured to a circle of the same area drawn around that centroid, so treat it as roughly right rather than surveyed.
Guidebooks to historic places and travel in Washington
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Titles come from Open Library's catalog, matched by subject heading or by title.
Reference
Questions people ask
When was Hanford B Reactor listed on the National Register?
Apr 3, 1992. It is also a National Historic Landmark, the higher of the two designations.
Source: National Park Service
When was Hanford B Reactor built?
1944.
Source: Wikidata
Where is Hanford B Reactor?
Near jct. of WA 24 and WA 240, Hanford Site, Richland vicinity, Benton County, Washington. The nearest national park unit is Ice Age Floods National Geologic Trail, 31 miles away.
Where is the nomination form for Hanford B Reactor?
The National Archives holds the nomination form, the document that made the case for listing.
Source: National Archives
Is there cell service at Hanford B Reactor?
FCC coverage maps show Verizon 4G LTE, AT&T 4G LTE, and T-Mobile 5G at the listed point. Coverage indoors and behind old masonry is another matter.
Source: FCC Broadband Map
Is there a wildfire near Hanford B Reactor right now?
1 active incident within 50 miles as of 2026-10-17, nearest Ancient Lakes, 39 miles away.
Source: Map
Sources
Location, type and contributing counts come from the National Park Service's National Register spatial data. Listing dates come from the National Register office's spreadsheet where it carries the listing. Construction date, architect, style, photograph and encyclopedia link come from Wikidata and Wikimedia Commons, matched on reference number 92000245. Nothing here is transcribed by hand. The nomination form and photographs ↗ at NPGallery are the original nomination as filed with the National Park Service, and the form is often the best description of the place. The description under "What it is" is the opening of the Wikipedia article, CC BY-SA.