Scientists discover historic sample of bomb-grade plutonium

Feb 26, 2009

(PhysOrg.com) -- Scientists in Washington state are reporting the surprise discovery of the oldest known sample of reactor-produced bomb-grade plutonium, a historic relic from the infancy of America’s nuclear weapons program. Their research, which also represents the first demonstration of how radioactive sodium can be used as a tool in nuclear forensics, appears in the current issue of ACS’ Analytical Chemistry.

In the new study, Jon Schwantes and colleagues note increased concern about the possibility of terrorists smuggling radioactive materials to make illegal nuclear weapons. As a result, scientists are stepping up efforts to identify and track the source of these radioactive materials using the advanced tools and techniques of a new field called “nuclear archaeology.”

The scientists describe efforts to determine the origin of an unknown sample of plutonium (Pu) found in 2004 in a bottle at a waste burial trench at the Hanford nuclear site in Washington. Hanford is the earliest location for U.S. plutonium production for nuclear weapons and now the focus of a massive environmental cleanup effort due to high levels of radioactive waste that remain at the site.

Using multiple pairs of “parent” Pu and “daughter” uranium (U) isotopes, the researchers were able to correct for chemical fractionation that occurred as a result of repackaging in 2004 and determine the age of the sample. Using this technique, they estimated that the Pu in the sample had been separated from U and fission products in 1944, making it the oldest known sample of bomb-grade plutonium produced in a reactor. The only older known samples of Pu-239 were produced by the late Glenn Seaborg and his associates in the beginning of the 1940's when the existence of the element was first confirmed and characterized.

The study identified the Clinton reactor in Oak Ridge, Tenn., as reactor of origin for this material, by comparing reactor burnup modeling results with measurements of minor Pu isotopes. These results were also supported by a series of historical documents tracking the material's movement from Oak Ridge and the processing at Hanford. “Aside from the historical significance of this find, this work provides the public a rare glimpse at a real-world example of the science behind and power of modern-day nuclear forensics,” the scientists note.

Provided by ACS

Explore further: Haunting tales in ship-wrecked silver

add to favorites email to friend print save as pdf

Related Stories

UK team unlocking secrets of North Korea volcano

Sep 03, 2014

More than a thousand years ago, a huge volcano straddling the border between North Korea and China was the site of one of the biggest eruptions in human history, blanketing eastern Asia in its ash. But unlike ...

Scientists expect traces of ocean radiation soon

Mar 15, 2014

Scientists have crowdsourced a network of volunteers taking water samples at beaches along the U.S. West Coast in hopes of capturing a detailed look at low levels of radiation drifting across the ocean since ...

How radioactive is our ocean?

Jan 15, 2014

Woods Hole Oceanographic Institution (WHOI) marine chemist Ken Buesseler began sampling and analyzing seawater surrounding the Fukushima Dai-ichi nuclear power plant three months after the 2011 disaster. ...

Recommended for you

The origins of handedness in life

19 hours ago

Handedness is a complicated business. To simply say life is left-handed doesn't even begin to capture the blooming hierarchy of binary refinements it continues to evolve. Over the years there have been numerous ...

Have our bodies held the key to new antibiotics all along?

23 hours ago

As the threat of antibiotic resistance grows, scientists are turning to the human body and the trillion or so bacteria that have colonized us—collectively called our microbiota—for new clues to fighting microbial infections. ...

Characterizing an important reactive intermediate

Oct 01, 2014

An international group of researchers led by Dr. Warren E. Piers (University of Calgary) and Dr. Heikki M. Tuononen (University of Jyväskylä) has been able to isolate and characterize an important chemical ...

User comments : 0