Legasov also presented the findings of an investigation to the International Atomic Energy Agency at the United Nations Office at Vienna, detailing the actions and circumstances that led to the explosion of Reactor No.

[2] While he was a shy student, he excelled in both academic work and social activities being elected secretary of his school's Komsomol committee.

[citation needed] In 1961, he graduated from the Faculty of Physicochemical Engineering at the Mendeleev Moscow Institute of Chemistry and Technology,[6] where he learned how nuclear fuel is processed, handled and disposed of.

[7] However, news of progress made by Neil Bartlett in Canada caused Legasov to switch his interest to noble gas chemistry.

[7] In 1962, he joined the graduate school in the Department of Molecular Physics of the Kurchatov Institute of Atomic Energy,[12]: 261  first as a junior then senior researcher, and finally as head of the laboratory.

A. Ustynyuk said of Legasov: "His main quality, which set him sharply apart from all the great organizing scientists I knew, was his exceptional dedication to the cause.

[7] Reactor 4 of Chernobyl nuclear plant exploded on 26 April 1986 at 1:23:45 a.m, releasing a massive amount of radiation and contaminating a large area.

Although not a reactor specialist, he became a key member of the government commission formed to investigate the causes of the disaster and to plan the mitigation of its consequences.

[7] At Vnukovo airport, Legasov met Boris Shcherbina, the head of the government commission dealing with the accident response.

[7] Viktor Alekseyevich Sidorenko called for immediate evacuation of Pripyat, which Legasov supported, as the situation was expected to deteriorate in the town, and this decision was approved by Shcherbina.

[22] On 2 May, he and other commission members reported to visiting high-ranking officials that this was no ordinary industrial accident but would require a significant containment effort, as well as a review of the future of the other reactors.

[1] When the first government commission group returned to Moscow, Legasov was asked to stay by Scherbina but was replaced by his scientific rival Evgeny Velikhov in the formal hierarchy.

[1] Water in the lower barboteur was drained but Legasov was convinced that an explosion was not possible,[7] in contrast to what some scientists and politicians feared.

[1] He also considered the possibility of ground water contamination to be extremely low, but precautionary work was initiated to cool the reactor using an underground system.

[7] Legasov considered these containment steps to be excessive but understandable, while also providing the infrastructure for the eventual construction of a shelter sarcophagus over the reactor.

[1] Around 9–10 May, Gorbachev requested a chronology of events and the cause of the accident in preparation for an interview, which Legasov provided in writing with a few edits from other investigators.

Some in the Ministry of Medium Machine Building (Sredmash) opposed his appointment, fearing Legasov would be difficult to control, since the nuclear establishment wanted to divert blame to others if possible.

[1] Legasov only spoke up to admit that scientists had failed in their duty[1] and that he had been warning about the safety problems of the RBMK reactor for years but nothing had been done.

[23] With the first draft of Legasov's report received by the Central Committee, some were shocked and one minister forwarded it to the KGB with the recommendation that the authors be prosecuted.

[1] In August 1986, Legasov presented the report of the Soviet delegation at a special meeting of the International Atomic Energy Agency in Vienna.

His report was noted for its great detail and relative openness in discussing the extent and consequences of the tragedy,[24] disclosed to Western media some defects in the RBMK reactor design such as the positive void coefficient, as well as problems with operator training.

[1] As a result of this work in Vienna, Legasov "became very popular, in Europe he was named the person of the year, he entered the top ten scientists in the world.

Perhaps in response to this, Legasov received criticism of his leadership and his handling of the containment of the Chernobyl reactor and was ostracized by some of his fellow scientists.

"[28] In spring 1987, a vote was held by the Kurchatov Institute to their Scientific-Technical Council with Legasov standing at the insistence of his mentor Anatoly Alexandrov.

[28] He gave interviews to Novy Mir and Yunost in which he changed his public stance and expressed his concern that cultural failings and Soviet science losing its way had led inevitably to nuclear disaster.

[22]Legasov continued his attempts to introduce reforms in academic chemistry by establishing an interdepartmental council to try to overcome stagnation in the field.

David R. Marples has suggested the adversity of the Chernobyl disaster on his psychological state was the factor leading to his decision to take his own life[6] and that Legasov had become bitterly disillusioned with the failure of the authorities to confront the design flaws.

"[5] Journalists Vladimir Gubarev and Yuriy Shcherbak claim that his suicide was a conscious attempt to draw attention to the lack of nuclear safety in the Soviet Union.

He is no better or worse than any manager of this rank, and he followed the accepted rules of the game, moving up the career and scientific ladder... he took on too much, especially in recent years.

[39] Legasov is portrayed by Ade Edmondson in the BBC docudrama Surviving Disaster (2006) and by Jared Harris in the Sky/HBO miniseries Chernobyl (2019).