Alexander Leipunsky — the nuclear physicist who brought plutonium to the masses

The Soviet nuclear physicist who survived Stalin's purges and the Nazi invasion to establish Ukraine as the birthplace of nuclear science.

Alexander Leipunsky Credit: Wikimedia Commons.
Alexander Leipunsky Credit: Wikimedia Commons.

One of the dreams of nuclear engineers is the production of plentiful and cheap electrical energy from nuclear reactors. One man with such a dream was the Soviet physicist Alexander Leipunsky (1903-1972) who helped to establish nuclear physics in Ukraine in the 1930s, build nuclear bombs in the 1940s, and then push a controversial Soviet programme from theory to industrial prototype plutonium-producing reactors.

Most nuclear reactors operate on principles of fission of uranium, others on fusion. Among the former are breeder reactors, so-called because they ‘breed’ plutonium that can be used to fuel other breeders — or to build nuclear bombs. Designated LMFBRs (liquid-metal fast breeder reactors), they operate with a liquid metal coolant such as sodium. The reactors produce electricity and desalinate water — but also have encountered technical challenges of frequent water and sodium leaks and sodium fires. Abandoned by France, Japan and the US because of safety and proliferation problems, Russia is building LMFBRs today, in no small part due to Leipunsky.

Soviet leaders proselytised science as crucial to the socialist dream, and from the 1920s they attracted many young men and women to participate in building glorious socialism. Leipunsky, with his working class social background, was precisely the kind of future scientist they desired.  He relished his work at the cutting edge of physics, was thrilled with the notion of being directly involved in penetrating the atomic nucleus, and after the war in protecting the motherland through nuclear weapons and reactors — and he would fuel them with plutonium (Pu).

A revolutionary man of working-class origins, a Communist Party member, a talented researcher, and an alpinist, Leipunsky arrived in Kharkiv, Ukraine, to establish a new physics institute, the Ukrainian Physical Technical Institute (UFTI) in 1928. Leipunsky led UFTI through the Stalinist purges and war with Nazi Germany, moved into the Soviet atomic bomb project, and spent his postwar years working on LMFBRs. His career reveals the vagaries of doing science in an authoritarian system. Around him, peasants died in a state-sponsored famine, his comrades fell in the purges, and he too was arrested. And yet, nuclear research moved forward. After the war, Leipunsky conceived the Soviet breeder reactor programme and gained almost unquestioned support for reactors with significant technical challenges including cost overruns, and sodium spills and fires. The US abandoned breeder reactors because of proliferation risks (it is much easier to build a bomb with Pu than with uranium), and technologically uncertain. The French and Japanese gave up on failed and costly programmes. But Russia, in the absence of scientific or public dissent, and in keeping with the memory of Leipunsky, a scientific hero, evinces few concerns about cost, risky technology, or personal sacrifices for science in the name of state power and Pu.

Leipunsky was born into a Jewish family on 7 December, 1903, in the rural Grodno region of today’s Belarus. Grodno’s Jewish population was decimated during the Holocaust. Leipunsky’s father worked as a road construction foreman but moved to Yaroslavl, northeast of Moscow, during the Great War. After the Russian Revolution, Leipunsky worked from 1918 as a messenger and an assistant foreman, graduated by correspondence from a technical school, and in 1921 gained entry — owing to his talents and his working-class background — to Petrograd (later Leningrad) Polytechnic Institute. A promising student, he undertook research across the street in the Leningrad Physical Technical Institute (LFTI), in 1926 defending his thesis, entitled The Collision of Electrons with Atoms and Molecules. He continued at LFTI, where he met his future colleagues in Ukraine and came to the attention of Abram Ioffe, the ‘dean’ of Soviet physics, whose vision included opening a series of physical technical institutes in regional cities designated for rapid industrial growth.

Ukraine: birthplace of nuclear science

When UFTI opened in 1928, Ioffe selected Leipunsky to join other, more senior members of the ‘Leningrad landing party.’ Kharkiv was then the capital of Ukraine and home to burgeoning machine tool and equipment industries. By his 30th birthday, the jovial and outgoing Leipunsky had become director of UFTI. He was considered a ‘Red [communist] Director’ because of his rapid promotion, owing to party membership. But he had earned the respect of his colleagues, who included two Nobel laureates, Peter Kapitsa and Lev Landau, for his penetrating analysis of the atomic nucleus. He was known affectionately by his initials, AIL, rather than the usual former name and patronymic.

Leipunsky’s arrival in Ukraine coincided with Stalin’s campaigns for the merciless industrialisation and collectivisation of agriculture. Kharkiv was in the centre of a fertile agricultural region where famine broke out because of collectivisation; several million people died. The Communist Party simultaneously carried out an attack on Ukrainian intellectuals:  writers, poets, painters and scientists accused of being ‘bourgeois nationalists.’ Within the walls of the institute, however, Landau, along with a future Nobel laureate, Lev Shubnikov, a low temperature specialist, Leipunsky and others conducted a world-class programme of theoretical, nuclear, and low temperature physics. In 1932, AIL and several other collaborators split a lithium atom just six months behind Ernst Rutherford’s team in Cambridge, England.

Autarky – the drive for economic independence from the West under Stalinism – would have an impact on science. But at first, the Communist Party welcomed foreign specialists to Kharkiv, even funding the publication in German of an institute physics journal. In 1933, the physicists held the first All-Union Nuclear Conference, attended by such well-known foreign specialists as Niels Bohr. Leipunsky himself presented a paper entitled Nuclear Fission. The conference gave impetus to the creation of the Commission for the Study of Nuclei, whose members included Leipunsky. Later, Viktor Weisskopf, future director of CERN; Rudolph Peierls, the German-born British specialist who played a major role in Tube Alloys; Lazslo Tisza and Fritz Houtermans; and Irene and Frederic Joliot-Curie all visited the institute. Leipunsky travelled to Germany and to the Cavendish Laboratory in Cambridge, England where he was likely the first in the world to perform an experiment to prove the existence of neutrinos.

The Great Terror

From 1936 until 1938, the Great Terror consumed the USSR as Stalin unleashed the secret police on common citizens, intellectuals and party officials. At least 750,000 people were executed, with millions more imprisoned in gulag camps. UFTI fell into the maelstrom, with Leipunsky, Landau, Shubnikov, and a number of foreign physicists arrested, too; several of them were shot. The tenor of institute meetings changed fundamentally, especially after NKVD (later the KGB) officials identified what they alleged was a nest of anti-Soviet activity. They singled out Jews, foreigners, Trotskyite oppositionists, and counter-revolutionaries. Shubnikov was executed in 1937; Lev Landau sat in prison for more than a year and nearly died.

Leipunsky was removed from his post of UFTI director on 16 September, 1937. He was allowed to continue working, but in June 1938 was arrested again, shipped to Kyiv, interrogated, flown to Moscow, and again interrogated. He was accused of consorting with such ‘enemies of the people’ as Shubnikov and Landau, and with foreigners. Under duress, he admitted inadequate vigilance towards these ever-present dangers and his unpardonable failings. Leipunsky survived, although he lost his party membership card. (He later recalled living with the stigma of being ‘expelled’ from the party for ten years). Two months later he was released from jail ‘for lack of evidence’, although the NKVD could have manufactured another conspiracy had it wished.

Leipunsky returned to nuclear research in Kharkiv, following up on the work of Otto Hahn and Lise Meitner, who had discovered nuclear fission. His research dovetailed with that of the nuclear and uranium commissions of the USSR Academy of Sciences, for whom he wrote two papers that set forth the possible variants of a chain reaction, ‘Nuclear Fission’ and ‘Uranium Fission.’ He estimated critical masses for variants of chain reactions, and conceptualised a heavy-water reactor using natural uranium.

Leipunsky, war and breeder reactors

Nazi armies rapidly conquered Ukraine after their invasion in June 1941, quickly reaching Kharkiv, where they levelled the city and destroyed UFTI. As soon as it was clear that Ukraine would fall, Leipunsky, his laboratory and other major Ukrainian institutes were evacuated to Ufa in the foothills of the Ural Mountains, where he established the Institute of Physics and Mathematics. From this point on, Leipunsky moved into atomic bomb work and to the development of breeder reactors.

From 1943, under the umbrella of the nascent atomic bomb project, directed by Igor Kurchatov, another LFTI alumnus, and his Laboratory No. 2 in Moscow (UFTI was designated Laboratory No. 1), Leipunsky conducted research on neutron-nuclear interactions. Given his study abroad and therefore excellent German and English language skills, in April 1946 he was charged with managing research in Laboratory ‘B’ in Sungul, Russia, which was staffed by Nazi specialists spirited out of Germany at the end of the war. From 1949, Leipunsky participated in the creation of the Institute for Physics and Power Engineering (IPPE – which has since been renamed in his honour) in Obninsk, Russia, site of the world’s first civilian nuclear power plant in 1954, and the base from which Leipunsky developed LMFBRs. Dozens of nuclear bomb facilities were establishing — growing like clouds of mushrooms.

During the Cold War, physicists held great authority because of the atomic bomb — and if they promised to produce Pu during the arms race with America, they did not have to ask twice for funding. In 1949, Leipunsky advanced a fast reactor design for electricity and Pu production. In addition to several experimental fast reactors, IPPE worked on prototype fast space reactors and nuclear submarine lead-bismuth liquid metal reactors. Step by step, year by year, they improved steels for fuel cladding, and produced pumps less likely to fail and conduit less likely to leak. Leipunsky’s efforts led to the construction of a series of breeder industrial prototypes — designated BN (fast neutron) -350, BN-600, and BN-800 — that appeared after his death.

What was his dream? Like many scientists associated with the bomb, in his later career AIL turned fully to the ‘peaceful atom,’ perhaps in the search not to be associated with weapons of mass destruction – Soviet scientists were denied the right to organise to protest the arms race, so why not produce electricity in breeders? AIL sought plutonium to produce electricity, desalinate water, and ensure the supply of fissile fuel for decades to come.  Toward these ends Soviet engineers built the BN-350 on a deserted peninsula in the Caspian Sea at Shevchenko (now Aktau, Kazakhstan) to power petrochemical production; it was closed in 1997 because of concerns about its safety. The Beloiarsk-based BN-600 was late to come on line, suffered dozens of accidents, and should have been shut down. But Rosatom, the Russian atomic corporation, has filed paperwork to extend its operation to 2040 with the claim it will be cost-effective, safe and substitute for the use of fossil fuels. Late in 2016, Russian engineers brought the BN-800 on line in Beloiarsk, so far, it is without problems; it is filled with five tonnes of plutonium and another 30,000 tonnes of liquid sodium coolant (sodium burns on contact with air, and on hitting water explodes). In spite of persistent technical and safety problems, Leipunsky’s successors hope that by the 2030s, LMFBRs will be competitive with other reactors — and provide Russia with more plutonium. However, while desiring plutonium, Russia wishes to destroy the memory of UFTI, and during the ongoing war in Ukraine, Russian soldiers have targeted both Kharkiv and the institute. As in Stalin’s time, the authorities are arresting scientists suspected of treason.

The USSR was enamored of Pu precisely because of its military applications. In fact, AIL’s legacy may be the fourteen military reactors – not electrical power reactors – that the Soviets built with total production of 150 tons of weapons grade plutonium, seventeen tons of which were employed in weapons tests or lost in three submarines that sank. Russia still possesses about 90 tons of Pu for weapons, much more than 38 tons in the US stockpile and than the 25 tons required to sustain its stockpile of 4,600 active warheads. Like many nuclear scientists who entered the field to produce electricity, AIL’s legacy instead is one of the risk of nuclear war.

During his career, Leipunsky published more than 120 works on atomic, nuclear, neutron and reactor physics in Soviet and foreign editions. He loved teaching, working as dean at the Moscow Institute of Physics and Technology for five years. The last president of the Soviet Academy of Sciences, Gury Marchuk, remembered Leipunsky, his doctoral dissertation advisor, for his administrative talent and tirelessness. Leipunsky’s wife, Antonina Prikhotko, was the director of Kyiv’s Physics Institute, so workaholic Leipunsky lived alone in Obninsk, always available to his students. He suffered two heart attacks, and a third attack killed him in August 1972. He was buried in Obninsk.


Paul Josephson