Nuclear History

Fast burst reactors: A historical primer

July 12, 2024, 7:02AMNuclear NewsJeremy Hampshire
The Godiva I device, an unreflected 54-kg sphere of 93.7 percent pure uranium-235, before (left [in the scrammed state]), and after (right) the February 3, 1954, criticality excursion that released 5.6 × 1016 neutrons and warped or broke several support structures of the device. (Photos: DOE)

Fast burst reactors were the first fast-spectrum research reactors to reach criticality by using only prompt neutrons with high-enriched uranium as fuel, creating a pulse for microseconds. Among many achievements, fast burst reactors were the first research reactors to demonstrate the ability of thermal expansion to terminate a pulse and to show how this could aid in reactor safety. In addition, fast burst reactors were pivotal in early fission studies including critical mass determination, criticality safety, the study of prompt and delayed neutrons, and much more.

Argonne National Laboratory’s thermal reactor program in Idaho

June 26, 2024, 7:00AMNuclear NewsR. N. Blomquist

In May’s Nuclear News (p. 86), we reviewed Argonne National Laboratory’s comprehensive work on fast reactors in Idaho. In this article, we summarize the light water reactor work there.1

In the early days, there were few data on the behavior of reactor materials under severe neutron bombardment. In collaboration, Oak Ridge National Laboratory and Argonne National Laboratory developed the Materials Testing Reactor (MTR) for the National Reactor Testing Station (NRTS) in Idaho. The materials tested in it over the course of 15,000 experiments were reactor fuel materials, structures, cooling systems, and shields. It operated from 1952 to 1970.

Argonne National Laboratory’s fast reactors in Idaho

May 23, 2024, 3:01PMNuclear NewsR. N. Blomquist
The Argonne-West laboratory site before it was merged with the Idaho National Engineering and Environmental Laboratory into today’s Idaho National Laboratory. The silver dome in the photo is Experimental Breeder Reactor-II, the silver structure with the flat top and sloping sides is the Zero Power Plutonium Reactor, and the brown boxlike structure behind ZPPR is the Hot Fuel Examination Facility. (Photo: Argonne National Laboratory)

Idaho’s nuclear energy history is deep and rich. The National Reactor Testing Station (NRTS) began its history as an artillery testing range in the 1940s.1 Following World War II, Walter Zinn, Argonne National Laboratory’s founding director and Manhattan Project Chicago Pile-1 project manager, proposed to the Atomic Energy Commission that a remote location be found for building test reactors. In 1949, he and Roger S. Warner, AEC’s director of engineering,2 developed a list of potential sites from which the NRTS was selected. Over the decades, quite a few companies and AEC national laboratories built 52 experimental and test reactors at the NRTS, including 14 by Argonne.3 (For a brief AEC video on the NRTS, see

Cecilia Payne-Gaposchkin: The woman who first grasped the elemental power of stars

May 10, 2024, 12:00PMNuclear News

When the U.S. Fusion Energy Outreach Team declared the second week of May as Fusion Energy Week, they were recognizing the May 10 birthday of Cecilia Payne-Gaposchkin—the British-born American astronomer who applied principles of quantum physics, chemistry, and astronomy to become the first to realize—at the age of 25—that stars and the universe itself are mostly composed of hydrogen and helium, and that the stars could be sorted by their spectra into groups that corresponded to the temperature of the stars.

Proof of concept: The Molten Salt Reactor Experiment in Nuclear News

May 9, 2024, 3:00PMNuclear News
The December 1960 issue of NN, which announced plans to build the MSRE, paired with a still image from a 1969 video on the MSRE produced by ORNL.

By late 1960, when the U.S. Atomic Energy Commission authorized plans to build a Molten Salt Reactor Experiment (MSRE) at Oak Ridge National Laboratory, the lab already had about 13 years of experimentation with molten salt reactors under its longest-serving lab director, Alvin Weinberg. The MSRE operated from 1965 to 1969, proving that molten salt reactors could operate reliably, and with alternatives to uranium-235 too.

Nicholas Tsoulfanidis—ANS member since 1969

April 26, 2024, 7:00AMNuclear NewsNick Tsoulfanidis
Left: Tsoulfanidis as a freshman, at age 17, at the University of Athens. Right: Nicholas Tsoulfanidis today.

We welcome ANS members who have careered in the community to submit their own Nuclear Legacy stories, so that the personal history of nuclear power can be captured. For information on submitting your stories, contact

As an undergraduate I studied physics at the University of Athens. I entered the university in 1955 after successfully passing a national exam (came up fourth in a field of about 700 candidates). Upon graduation and finishing my mandatory two-year military service, the plan was to teach physics either in a public high school or as a tutor for a private for-profit institution, preparing high school students for the national exam.

NRC to discuss decommissioning of historic NS Savannah

April 16, 2024, 9:30AMNuclear News
The NS Savannah. (Photo: NS Savannah Association)

The Nuclear Regulatory Commission will hold a public meeting on May 8 to discuss the license termination process for the retired nuclear-powered merchant ship, the NS Savannah. During the meeting, NRC staff will discuss the license termination process and receive public comments on the remaining cleanup activities described in the license termination plan for the historic ship, which may see a second life as a floating museum.

The SNAP-10A reactor power system

April 10, 2024, 9:31AMNuclear NewsJeremy Hampshire
Left: A technician inserts a steel tube containing fuel into the SNAP-10A reactor core vessel. (Photo: DOE) Right: A cross-section view of the reactor. (Image: DOE)

Systems for Nuclear Auxiliary Power (SNAP) was an Atomic Energy Commission program with the goal of producing a portable and dependable power source centered around nuclear technology that could be utilized in land, sea, and space applications. The program aimed to provide a compact reactor—a necessity for space applications—and ran from 1955 until 1973, when it was discontinued.

James Behrens—ANS member since 1979

April 1, 2024, 12:00PMNuclear News
Left: Behrens as a physics lecturer in 1969 at the University of Illinois—Urbana-Champaign. Right: Behrens at home today with his new pup Snowflake.

We welcome ANS members who have careered in the community to submit their own Nuclear Legacy stories, so that the personal history of nuclear power can be captured. For information on submitting your stories, contact

The James Wm. Behrens family legacy in America starts with Henry H. Behrens, who came across the pond from Germany in 1857. He was later joined by Wilhelmina, also from Germany, and they were married in Alton, Ill., in about 1862. One of their sons, George Wm. Sr., was my grandfather. He and his wife, Frances Walker (of Irish and English descent), had three sons, one of whom (George Wm. Jr.) was my father. I was born in 1947 and raised in the small country town of Bunker Hill, Ill. I attended Bunker Hill elementary and high schools, graduating from the latter in 1965.

Nuclear moments

March 21, 2024, 9:30AMNuclear NewsGrace Stanke

Grace Stanke

I just spent 13 months as Miss America 2023 advocating for nuclear energy. Throughout those 13 months, I traveled approximately 280,000 miles to 23 states and eight countries. I have now seen eight different power plants (seven in the United States and one in Japan). I visited radiological isotope production facilities, reprocessing facility construction sites, research facilities, and more. My work extended to visits at schools, trips to talk with state and national legislators, and stops at varying professional groups looking to learn more about nuclear science. It certainly was an interesting year, and one that I could not have foreseen.

Experiences: One thing that this year has made me appreciate about the nuclear industry: No matter what facility, and no matter what country you are in, there is always a plan. I never thought I would be so giddy to walk into a power plant and sit down for a pre-job brief, but honestly, I love them now. The desire to be prepared and have a plan is not so present in most other industries!

Clementine—The world’s first fast neutron reactor

March 19, 2024, 3:00PMNuclear NewsJeremy Hampshire
The exterior of the Clementine nuclear reactor at Los Alamos Scientific Laboratory. (Photo: LANL)

In March 1949—75 years ago this month—the 25-kilowatt reactor known as Clementine reached full power. As an experimental reactor, it had a rather long and successful run. It was the world’s first fast neutron (high-energy) reactor and operated from initial criticality in 1946 to final shutdown in 1952.

The Sodium Reactor Experiment

February 23, 2024, 3:01PMNuclear NewsJeremy Hampshire
The SRE nuclear facility in 1958. (Photo: DOE)

In February 1957, construction was completed on the Sodium Reactor Experiment (SRE), a sodium-cooled, graphite-moderated reactor with an output of 20 MWt. The design of theSRE had begun three years earlier in 1954, and construction started in April 1955. On April 25, 1957, the reactor reached criticality, and the SRE operated until February 1964.

MARAD decommissioning Savannah : What’s next?

February 16, 2024, 9:30AMANS Nuclear Cafe
The N.S. Savannah. (Photo: N.S. Savannah Association)

What will happen to the retired nuclear-powered merchant ship, the N.S. Savannah? The Maritime Administration (MARAD) of the Department of Transportation is investigating possibilities for the vessel’s future, whether it be in disposition, transportation, or preservation.

Richland critiques “home, safety, [and] whiteness” of proud nuclear company town

February 12, 2024, 12:03PMANS Nuclear Cafe


The documentary film Richland, which won awards at the Tribeca Festival and Sheffield (U.K.) DocFest last year, continues to gain exposure. Directed by Irene Lusztig, a self-described “feminist filmmaker, archival researcher, educator, and seamstress,” the documentary explores the community and “nuclear origin story” of Richland, Washington, a town that was built by the U.S. government to house Hanford Site workers who made the weapons-grade plutonium for the atomic bombs of the Manhattan Project.

Washington State University offered a free screening of the documentary last week at its main Pullman campus, followed by a discussion with the director and Robert Franklin, an assistant professor in history at the university’s Tri-Cities campus and the assistant director and archivist for the Hanford History Project.

2023 in Review: October–December

January 16, 2024, 3:01PMNuclear News

Another calendar year has passed. Before heading too far into 2024, let’s look back at what happened in 2023 in the nuclear community. In today's post, compiled from Nuclear News and Nuclear Newswire are what we feel are the top nuclear news stories from October through December 2023.

Stay tuned for the top stories from the rest of the past year.

2023 in Review: July–September

January 12, 2024, 9:29AMNuclear News

Another calendar year has passed. Before heading too far into 2024, let’s look back at what happened in 2023 in the nuclear community. In today's post, compiled from Nuclear News and Nuclear Newswire are what we feel are the top nuclear news stories from July through September 2023.

Stay tuned for the top stories from the rest of the past year.

Remembering ANS Past President Joseph Hendrie

January 11, 2024, 3:01PMNuclear News

Joseph Hendrie, Brookhaven National Laboratory physicist, NRC chair, and ANS past president (1984–1985), passed away in his home in Bellport, N.Y., on December 26 at the age of 98.

Hendrie, an American Nuclear Society member since 1956, was a leader in the nuclear community for much of his 45 years in nuclear reactor safety research. He served as the deputy director for technical review of the Atomic Energy Commission’s Directorate of Licensing from 1972 to 1974 and then was appointed chair of the NRC in 1977 (serving a second stint as chair in 1981—the only person to serve two nonconsecutive terms in that role).