Tales of the Soviet Atomic Project

Lee Pondrom University of Wisconsin XXIII Baldin Seminar Nemenov’s story Tehnika-Molodezhi1975-06-20 Igor Kurchatov Some background information

• On February 11, 1943, the State Defense Committee established a group to work on solutions to the uranium problem. • Abram Ioffe recommended 39 year old Igor Kurchatovas scientific director of the effort. • On April 12, 1943, the USSR Academy of Sciences created Laboratory #2, headed by Kurchatov.(#1 was Kharkov, #3 became ITEF). Laboratory #2

• At first, because so many buildings in Moscow were vacant – operations had moved east – space was found in the Institute of Seismology on Pyzhevsky Street across the river south of the Kremlin. Georgy Flerov began measuring neutron cross sections nearby, in the Institute for Inorganic Chemistry. Here for the first time guards appeared at the doors. • Kurchatov needed more open space, and started looking outside Moscow. Georgy Flerov

Student of Kurchatov at LFTI

Lt. Flerov wrote to Stalin about nuclear weapons Co-discoverer of spontaneous fission of uranium Laboratory #2

• Golovin describes the site of the present Kurchatov Institute thus: • Kurchatov chose a dilapidated 3 story brick building near the ring railroad, next to an open potato field, about 1 km from the Moscow river. There were 2 other broken down one story brick buildings a few hundred meters away, and 2 storage bins without roofs. Five hundred meters further was a small 2 story factory making medical x-ray equipment. Laboratory #2 landscape

Photo from Alex Wellerstein Moscow in 1943

Leningradsky prospect

Dynamo lab Byelorussky vokzal

Zoo Kremlin Laboratory #2 tent

Photo from Alex Wellerstein Exponential pile inside tent

Photo from Alex Wellerstein Nemenov’s assignment

• In early March, 1943, the number of physicists at Laboratory #2 could be counted on your fingers. Kurchatovcalled a meeting in his oversized office. Alikhanov, Kikoin, and Nemenov were in attendance. • A first task was to produce plutonium for physical and chemical studies. Reactor production of 239Pu is the best way. Nemyonov’s assignment

• In 1943 the USSR had no reactors, and Laboratory #2 had no cyclotron. The first cyclotron was built at the Radium Institute in Leningrad in the mid 1930’s. A second, higher energy cyclotron was started at LFTI by Kurchatov, but interrupted by the war. Cyclotron production of neutrons

• Bombard a lithium target with 4-5 MeV deuterons. • Possible reactions 7Li(d,n)8Be, or • 6Li(d,n)7Be • For 4 MeV d’s, the first gives 13 MeV neutrons at 900, the second 5.5 MeV neutrons at 900. • An internal target -> radially outward n’s. Neutron production of plutonium

• Moderate the neutrons with paraffin around a 238U target. Then slow neutron capture: • n+238U->239U->239Np+β+ν; 23.4 min ½ life • 239Np->239Pu+ β+ν; 2.36 day ½ life. • 239Pu is an α emitter, ½ life 24,000 years. Cyclotron layout Plutonium yield from cyclotron

• Take 100 μ amp deuteron current -> 1010 n/sec on the uranium target • Assume 100% efficiency -> 1010 captures/sec • Running 24/7 for a year gives 3x1017 Pu atoms or about 100 μ gm of product. Nemenov’s assignment

• Kurchatov wanted to commission a new cyclotron for Laboratory #2. The D’s and RF system were built of copper. Copper was unobtainable during the war (used in shell casings). But Kurchatov remembered that D’s and RF system were assembled in Leningrad before the war. • Accordingly, he sent Nemenov and an engineer named Glazunov into Leningrad in the spring of 1943 to retrieve the copper components. Western Soviet Union 1943 Blockaded Leningrad The Trip

• Nemenov and Glazunov flew from Moscow into blockaded Leningrad. The flight was loaded with mail and packages for relatives inside the blockade. • They landed east of Lake Ladoga and waited for darkness to fly into the city in a light plane. • They landed at Okhtinsky airport, and were transported to LFTI. Leningrad

• Mikhail Pervukhin, People’s Commissar for Chemical Industries, wrote a letter that they carried, requesting cooperation from the local government. The day after arrival they went to the Smolny Institute to deliver the letter. • The Leningrad Soviet gave them authorization to go anywhere in the city at any time, regardless of air raids or artillery attacks.(There was a strict police enforced curfew.) Mikhail Pervukhin

Electrical engineer by training

Scholarly looking man MIT cyclotron RF system

λ/4 stubs ω=eB/m

B=1.5 T λ=13 m protons

D’s +ion source In Leningrad

• Nemenov and Glazunov had to do all of the leg work themselves. LFTI colleagues were too malnourished to do any heavy lifting. • They reported regularly to Kurchatovin Moscow, using the telephone line in the Smolny. They were in Leningrad for 2 months. • Copper and brass for the cyclotron D’s and vacuum tank were buried in the LFTI yard! In Leningrad

• They dug up the copper, collected other RF hardware, insulators, and vacuum grease, and packed it all for shipment back to Moscow. • Later on LFTI would miss the stuff, and ask where it went. Most of LFTI was in Kazan. • They made a trip to the Elektrosilafactory, that must have been near the German lines, to look for the cyclotron magnet. It was there in pieces. 35 shells fell on the factory grounds while they were there. Back to Moscow

• The parts were loaded onto rail cars with help of a group of partisans for the trip to Tikhvin, due east of Leningrad. • Nemenov and Glazunov elected to fly back, rather than risk being shelled on the train. • In the meantime, Kurchatovhad started work on forging the cyclotron magnet and coils, but much supervision was still required. Cyclotron magnet and coils

Magnet has 80cm dia pole tips, 20 cm gap, 1.4 T field

Iron weighs 16 metric tons, coils 1 ton. 100 turns 2230 amperes. Back at Laboratory #2

• The accelerating chamber had to be built. A vertical axis lathe was used to machine the chamber. The process took 2 weeks, after which all involved had a small banquet. • The finished magnet weighed 25 tons. A hole was cut in the wall of the lab, and a log road (corduroy) was laid outside to help move the magnet. • A local tank battalion furnished a T-34 to smooth out the log road. The best mill-wrights in Moscow moved the magnet along a route chosen by the police to Laboratory #2. Cyclotron commissioning

• Leaks in the vacuum tank were found by submerging it in water, applying air pressure inside, and looking for bubbles. • The cyclotron was installed on the first floor of the main 3 story building. The control room was on the same floor, separated by a shielding wall. The power supplies were in the basement. Cyclotron commissioning

• On the day of start-up, Kurchatovhad a meeting at the office of Boris Vannikov in the Kremlin. He said to call him with a progress report. • There were the usual problems. The D’s would not hold voltage, and had to be ‘trained’. • After two hours the surfaces were cleaned, and Nemenovstarted the ion source, RF, and checked the magnetic field. Boris Vannikov

He looks tough, but he was a big help. Boris Lvovich Vannikov

• Born in 1897 in Baku • Trained at Moscow Technical School named N.E. Bauman • 11 Jan 1939-9 June 1941 – People’s Commissar for armament. • 16 Feb 1942-7 Jan 1946 – People’s Commissar for armament. • 1945-1953- Deputy to L. P. Beria on the Special Committee for the Atomic Project. Boris Vannikov

• In prison for the June, 1941, German invasion. • Released to coordinate movement of industry to the east. • In prison again January 1942. Summonsed to the Kremlin by Stalin, and put in charge of supply of all war material to Red Army. • Later worked closely with Igor Kurchatov. Back to Nemenov’s cyclotron-Beam!

• After many adjustments and minor repairs, deuterons were accelerated out to an internal target, and neutrons were detected across the room. • 50 μ amps measured on a probe at target radius. • They replaced the vacuum window, and extracted beam into the room. Call to Vannikov’s office, 25 September, 1944 • Vannikov answered the phone, but Nemenov saved the news for Kurchatov. • Kurchatov returned to the lab about 3 am, to witness success, and at 4 am they all went to his house for celebration with a glass of champagne. • Kurchatov said: ”The day after tomorrow we will begin irradiation.” • Uranium nitrate was irradiated until December, 1945 to produce plutonium for physical and chemical studies. Igor’s brother Boris did the chemistry. conclusions

• Much of the lab work for nuclear weapons is experimental physics. • No one working on the Soviet Atomic Project was easily scared. • Nemenov and Glazunov had plenty of clout in wartime Leningrad, thanks to Pervukhin’s letter. Thanks to friends at Dubna who have helped in this project

The speaker in front of F-1 reactor