Chasing Bitterfeld Calcium
Henry S. Lowenhaupt - Chasing Bitterfeld Calcium
P. 29
In mid-1949, for instance, the distilled calcium stockpile of 680 tons easily could have produced 1500 tons of uranium metal, […]
P.29-30
Operation Spanner is perhaps of more interest: in the spring of 1948 Eric Welsh was musing along with Charlie Campbell-presumably, as usual, about which way the cat would jump-when he broached the idea of sabotaging the Russian plutonium effort. Both were aware of the Russian specifications on distilled calcium which called for less than one part per million of either boron or cadmium. These substances simply soak up neutrons, thereby tending to stop nuclear reactions. Welsh was all for dropping in a pinch of boric acid and "buggering the works." But he had been a chemist and was afraid his man at Bitterfeld would be caught through routine batch analysis. Then Charlie Campbell remembered that in 1944 the Manhattan District had a really secret plant for making boron enriched in the neutron-catching boron-10 isotope. In nature, boron contains 20% boron-10. The Manhattan District product was nearly 90% pure. It should work fine. Col. Seeman liked the idea and arranged for discreet inquiry to be made at the appropriate levels of the AEC. The answer came back they'd be glad to loan us some excellent material, but if we lost any of it, not to admit it!
Then came the usual period of agonizing detail. British analysis of 1947 Bitterfeld calcium disagreed with U.S. analyses in the boron content. Who really knew how to analyze accurately for boron, and could the other laboratory learn to reproduce the method? What really was the accuracy of the Bitterfeld analyses? How much boron would they really let pass? Could anyone obtain reliable isotopic analyses of millionths of a gram of boron?
Professor A. J. Demster of the University of Chicago indicated he had just received a mass spectrograph which could handle these small amounts of boron. He knew a microchemist who could prepare the samples for his analysis. It was agreed on 11 June 1948 to exchange old Bitterfeld calcium samples with the UK, and analyses as well.
All went well at first. The analytic problems were worked out. The amounts of enriched boron per batch of distilled calcium were worked out. Calculations indicated there was some risk, but the Russians would be hard put to conclude anything except some extra boron contamination in the billets-there was no indication they had mass spectrographs of the sophistication of Prof. Demster's. If, however, a simple neutron absorption test-a routine test in the U.S.-were performed, it would reveal that a whole batch of uranium (that made from the contaminated calcium) was bad. It was decided to go ahead. The sabotage chemical was transferred without records to us, and then on to the British.
Then calcium distillation at Bitterfeld stopped for a year. Welsh's agent started to worry. On grounds that he would be caught, he refused to add to the raw calcium the amount of enriched boron needed to make sure that enough contamination would pass through the distillation process into the uranium.
Finally, in August 1949, the Russians detonated their first plutonium bomb secretly. The Air Force Technical Applications Center intercepted the radioactive debris almost by happenstance.
P. 29
In mid-1949, for instance, the distilled calcium stockpile of 680 tons easily could have produced 1500 tons of uranium metal, […]
P.29-30
Operation Spanner is perhaps of more interest: in the spring of 1948 Eric Welsh was musing along with Charlie Campbell-presumably, as usual, about which way the cat would jump-when he broached the idea of sabotaging the Russian plutonium effort. Both were aware of the Russian specifications on distilled calcium which called for less than one part per million of either boron or cadmium. These substances simply soak up neutrons, thereby tending to stop nuclear reactions. Welsh was all for dropping in a pinch of boric acid and "buggering the works." But he had been a chemist and was afraid his man at Bitterfeld would be caught through routine batch analysis. Then Charlie Campbell remembered that in 1944 the Manhattan District had a really secret plant for making boron enriched in the neutron-catching boron-10 isotope. In nature, boron contains 20% boron-10. The Manhattan District product was nearly 90% pure. It should work fine. Col. Seeman liked the idea and arranged for discreet inquiry to be made at the appropriate levels of the AEC. The answer came back they'd be glad to loan us some excellent material, but if we lost any of it, not to admit it!
Then came the usual period of agonizing detail. British analysis of 1947 Bitterfeld calcium disagreed with U.S. analyses in the boron content. Who really knew how to analyze accurately for boron, and could the other laboratory learn to reproduce the method? What really was the accuracy of the Bitterfeld analyses? How much boron would they really let pass? Could anyone obtain reliable isotopic analyses of millionths of a gram of boron?
Professor A. J. Demster of the University of Chicago indicated he had just received a mass spectrograph which could handle these small amounts of boron. He knew a microchemist who could prepare the samples for his analysis. It was agreed on 11 June 1948 to exchange old Bitterfeld calcium samples with the UK, and analyses as well.
All went well at first. The analytic problems were worked out. The amounts of enriched boron per batch of distilled calcium were worked out. Calculations indicated there was some risk, but the Russians would be hard put to conclude anything except some extra boron contamination in the billets-there was no indication they had mass spectrographs of the sophistication of Prof. Demster's. If, however, a simple neutron absorption test-a routine test in the U.S.-were performed, it would reveal that a whole batch of uranium (that made from the contaminated calcium) was bad. It was decided to go ahead. The sabotage chemical was transferred without records to us, and then on to the British.
Then calcium distillation at Bitterfeld stopped for a year. Welsh's agent started to worry. On grounds that he would be caught, he refused to add to the raw calcium the amount of enriched boron needed to make sure that enough contamination would pass through the distillation process into the uranium.
Finally, in August 1949, the Russians detonated their first plutonium bomb secretly. The Air Force Technical Applications Center intercepted the radioactive debris almost by happenstance.