Background to the Zippe Files

The gas centrifuge has emerged as the most popular and efficient device for enriching uranium in the fissile isotope U235

. Uranium-235 is the isotope used for nuclear fission that can generate both electricity and bombs.

Many people have contributed to gas centrifuge development but one name stands out as a major contributor to the technology: Gernot Zippe
. Zippe was an Austrian mechanical engineer who was captured by the Soviet Union at the end of World War II. He was taken to Russia where he participated in the design of the first generation of uranium enrichment centrifuges based upon subcritical rotors made of high strength aluminum. While the Russians denigrate his efforts, many of his ideas ended up in the Soviet centrifuges that are the basis of Russian uranium enrichment today.

When Zippe was released from the Soviet Union he returned to Germany and went to the United States where he worked on the fledgling US uranium gas centrifuge enrichment program at the University of Virginia. There he conducted studies of small aluminum machines that were the basis for the much larger US centrifuges that are still under development today.

Unfortunately Zippe was not an American citizen and his work became classified as the US program matured. So he was forced to leave the United States and he joined the European uranium enrichment consortium. In so doing he contributed to yet a third gas centrifuge development program that is the basis for the successful URENCO uranium enrichment consortium today.

Therefore it is not unreasonable to label Zippe as the father of the modern gas centrifuge program today, in Russia, the US, Europe and even Brazil and Japan. Unfortunately His early designs have now propagated to Pakistan and Iran as well, so his handiwork is spread around the world today [See also the note following the post below].

Zippe’s early works were unclassified and published by the University of Virginia for the US Atomic Energy Commission. The unclassified early work is clearly not a proliferation concern today, but these rare reports offer insight into the mind of a remarkable man and his place in the history of nuclear energy in the 20th century. Zippe died in Austria in 2008.

Here are the files:

• “The Development of Short Bowl Ultracentrifuges,” Dec. 1, 1958
• “The Development of Short Bowl Ultracentrifuges,” July 1, 1959
  
• “The Development of Short Bowl Ultracentrifuges,” Nov. 6, 1959
• “Development and Status of Gas Centrifuge Technology“

How Journalists May Use the Zippe Files

The 55-year-old documents can still be relevant for journalists writing about nuclear technology and international politics today.

For example, the “Elementary Theory of the Gas Centrifuge,” explained under Appendix A of the first document, shows why today’s policymakers negotiating with Iran are intent on persuading the Persian Gulf nation not to upgrade the quality of their centrifuges at Natanz: “doubling the peripheral speed results in a sixteen fold increase in the separative power and therefore one sixteenth as many centrifuge units in a plant of a given capacity.”

While real-world experience following the publication of Zippe’s papers show that doubling centrifuge speed limits comes closer to only raising output by a factor of four, the section nevertheless illustrates how innovation yields greater efficiency
.

Another notable section for journalists is found on page 6, under a “General Description of Method.” Using the prototype machine, Zippe and his colleagues calculated the resources necessary to produce “one kilogram of uranium metal enriched to 96% U235 per day.” The team determined the costs of single centrifuge would be below $1,000 in 1958. Adjusting for inflation, where each Iranian centrifuge costs around $6,000 in 2013 dollars, we may make a back-of-the-envelope calculation that the country’s installed P1 centrifuge machines (not counting the buildings) cost around $93 million, assuming they are modeled after Zippe’s single-tube design.

Why is it important for journalists to have a general understanding of the technology and costs behind Iran’s nuclear program? One important reason is that it allows them to critically interpret information foisted upon them by policymakers.

In 2005, the U.S

. State Department presented peers and the press with a curious deck of slides entitled “Iran’s Nuclear Fuel Cycle Facilities: A Pattern of Peaceful Intent?” Jeffrey Lewis at Arms Control Wonk wrote about the document’s unusual provenance in a post shortly after it was made public
.

Any journalist covering the Iran issue in 2005 will recall the great emphasis that U.S. officials place on the economics of enrichment. They argued that Iran’s nuclear program couldn’t possibly be peaceful because the program simply didn’t make any economic sense. Leaving aside the arrogance explicit in their arguments — prescribing that Iran should focus on its oil and gas sectors rather than pursue nuclear-energy diversification — diplomats glibly ignored the underlying cost factors of enrichment.

According to Zippe’s calculations, a single centrifuge costs about as much as two roundtrip business-class airline seats that IAEA inspectors use when they conduct routine verification in Iran. Perhaps not chump change to a journalist, but well within the cost boundaries of a sovereign nation that can collect revenue and export goods.

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Note: We corrected the text to strike the word “unfortunately” before the description of how Zippe’s machines conquered the world. It was a value judgement that the Austrian may not have agreed with. After all, Zippe considered enrichment-technology transfer as something that could create international stability:

“Let us hope that the new time of global cooperation and peaceful competition to find the best solutions for the benefit of mankind is on the horizon,” Zippe wrote. “Gas-centrifuges for uranium enrichment is an example of such a global cooperation and made an important contribution to the fact of Cold War between East and West came to an end without a holocaust.”