Y-12 AND THE ATOMIC BOMB

JANE WARREN LARSON

Looking back at the early years

On August 8, 2002, The Washington Post noted that “Highly enriched uranium from dismantled Russian H-bombs and warheads...could be sent to the Energy Department’s Y-12 plant in Oak Ridge, TN, for storage or further processing.” Within the same timeframe, Western newspapers began to report that North Korea has admitted being involved in nuclear matters. And a report my husband wrote in 1996 about the Y-12 electromagnetic separation process finally was declassi- fied by the Atomic Energy Commission.

The timing of these three very different reports dealing with nuclear weapons is coincidental, of course. But as I look back on my family’s experience at Y-12, it strikes me that nuclear affairs may be entering a new phase across the world. Secrets are being revealed, and threats reevaluated. Perhaps this time around, nuclear knowledge can be handled more forthrightly, as my generation handled our introduction of it in the early 1940s.

THE U-235 STORY

In the early 1940s, there were three separate plants in Oak Ridge attempting to produce isotopes of uranium. The Y-12 plant, where E.O. Lawrence’s calutrons were built, was Clarence E. Larson’s and my old stomping ground. And the Y-12 plant, after all, was where Manhattan Project scientists finally succeeded in collecting the isotope U-235 to make the first atomic bomb.

I remember walking down through the woods in late 1943, on a wooden boardwalk at nightfall to reach the gate to the first building, which would house experimental work before the production buildings were started. Giant earth movers were roaring away nearby at a huge hill that would be flattened into a parking lot by morning. The building at the time seemed positively lost in the lonely Tennessee valley with steep wooded slopes on each side. I had been told the site was chosen for its obscure location, and because of the nearby Tennessee Valley Authority, a mighty source of electric power.

In September, I had taken courses to learn about the Y-12 calutrons. These were essentially large vacuum tanks in the shape of a D, with magnets between them generating a strong magnetic field. With power, a moving stream of heated uranium vapor formed, separating into the lighter and heavier isotopes as the magnetic field moved it around the curve of the D and into collection boxes. In production, the natural uranium was separated in an enrichment of approximately 25 percent U-235, the vital product. In the Beta stage, the product from the Alpha stage was enriched to approximately 95 percent—at least that was the goal. Design changes were being made constantly.

My job was to report every morning to the director about what had gone on the night before. Did we get an acceptable vacuum in the D’s? Was the magnetic field behaving? What were the beam readings? Later, I would help with scientific reports as an editor and, later still, help organize the large volume of scientific data collected by the Y-12 scientists.

Clarence Larson had spent time in Berkeley as a graduate student in chemistry under E.O. Lawrence, and then followed Lawrence’s calutrons to Oak Ridge. Eventually, he supervised the Y-12 effort, climbing in responsibilities as the tasks got harder. Many years later, E.O. Lawrence was best man at Clarence’s and my wedding.

At Y-12, many difficulties developed with the enlarged calutrons. The aim was to collect enough of the precious isotope in time to forward it to Los Alamos, put it into a bomb casing, install the bomb in a specially fitted airplane, and send this secret weapon to drop on Japan and end the war in the Pacific. General Leslie R. Groves, the Army engineer in charge of coordinating the Manhattan Project, drove everyone hard. We all knew that July 1945 was about the last possible month for completing the bomb, beyond which time American forces would have to invade Japan.

But there was a hitch in the planned timetable. The separated U-235 that landed in the Beta calutron collection boxes had to be removed and prepared for shipment, and this proved chemically impossible to do. All kinds of substitute procedures were tried as winter turned into spring. One hundred more chemists were hired. I remember hearing about the receiver boxes being submerged in tubs of rare, exotic solutions, and of chemists putting in 14-hour days. All the silver in Fort Knox was appropriated for building production coils since copper was in short supply.We still thought the Germans might beat us to the punch. Then I learned that a new Larson procedure had succeeded: The needed amounts of bomb material could be produced and sent off to Los Alamos.

Those were desperate days in 1944 and early 1945. Pearl Harbor was still very much a bitter memory and we were re-arming, helping Europe end its war, and gradually becoming convinced that an atomic bomb was the only thing that would end the war in the Far East. But could we get it done? My father (Stafford L. Warren, CC 1947-1981), who was a physician, radiologist, and chief medical officer of the Manhattan Project, was present at the critical Alamogordo test firing on July 16, 1945. In his spoken memoirs after the war, he told of stringing wire with his men up from ground zero into the mountains around the New Mexico test site at 1,000-foot intervals and tying rats to the wire “with very strong battery clips.”The aim was to get first-hand readings on explosive power and radiation exposure at a time when only crude instruments were available.

After the war, there were many more stories about Oak Ridge. Attention was paid to see that every ounce of silver was returned to Fort Knox. In May 1996, the president of the Atomic Energy Society of Japan came to Oak Ridge for the dedication of the International Friendship Bell. This four-ton bronze bell, cast in Hiroshima, is inscribed with four dates marking Oak Ridge’s pivotal role in history: Pearl Harbor, December 7, 1941; Hiroshima, August 6, 1945; Nagasaki, August 9, 1945; and VJ Day, September 2, 1945. But the best tale, I think, came from the Oak Ridge Journal. The paper said that on August 6, 1945, somebody stuck his head in Clarence Larson’s laboratory and told him, “Hey, they dropped the bomb!” There was a moment of silence and then Clarence queried urgently, “Did it go off?” Yes, the bomb worked, and the war ended.

EPILOGUE

As I reflect on these events, it seems to me that there are many lessons for the most part left unspoken.We were intent on doing our part to end the war, but also realized that we were working on a source of clean energy that had great potential applications for peacetime. The presence of nuclear technology meant energy, not necessarily the end of the world. Yet, we remain fixated on the horror of nuclear war. At Oak Ridge, the “Loose Lips Sink Ships” slogan was posted everywhere, and wartime secrecy was a highest priority. And now we are obsessed with the unwelcome reality that we can no longer control the flow of information about weapons technology.

Today,much nuclear information has been declassified. According to an April 2002 report in London’s Daily Telegraph, Britain’s Ministry of Defence “has placed a step-by-step guide on how to build an atomic bomb in Britain’s Public Record Office.” The plans are available to anyone who requests this information. To me, the fact that Clarence’s paper on the U-235 separation process was declassified in 2002 reveals that this information is already out there.

There’s no shutting the barn door, of course. We have been dealing with the dismantling of the former Soviet Union’s nuclear arsenal for over a decade, while dismantling our own outdated nuclear weapons. We would be foolish, even naïve, to think that we have the ability to keep nuclear weapons technology out of the hands of North Korea, Iraq, or any other country. So, isn’t it time we started rethinking our strategy regarding containment of all weapons of mass destruction, and focus or at least redirect our concerns about the growing number of nuclear-armed states? A wiser course might be to help nations develop safe nuclear energy, beginning with programs in our own country that would cut down on our hardly excusable dependence on coal. Perhaps it is time we started focusing on more constructive ways to improve our relations with North Korea and other countries that are involved in attaining nuclear status.

Jane Warren Larson (CC ’02), the widow of Clarence E. Larson (CC 1959-1999), is a former librarian and science writer. Her last article for the Cosmos Journal in 2000 discussed the need to create durable records.

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