Since then, heavy water has been an essential component in some types of reactors, both those that generate power and those designed to produce isotopes for nuclear weapons.

These heavy water reactors have the advantage of being able to run on natural uranium without using graphite moderators that pose radiological[8] and dust explosion[9] hazards in the decommissioning phase.

[27] In the 1930s, it was suspected by the United States and Soviet Union that Austrian chemist Fritz Johann Hansgirg built a pilot plant for the Empire of Japan in Japanese ruled northern Korea to produce heavy water by using a new process he had invented.

[29] In October 1939, Soviet physicists Yakov Borisovich Zel'dovich and Yulii Borisovich Khariton concluded that heavy water and carbon were the only feasible moderators for a natural uranium reactor, and in August 1940, along with Georgy Flyorov, submitted a plan to the Russian Academy of Sciences calculating that 15 tons of heavy water were needed for a reactor.

In October 1946, as part of the Russian Alsos, the NKVD deported to the Soviet Union from Germany the German scientists who had worked on heavy water production during the war, including Karl-Hermann Geib, the inventor of the Girdler sulfide process.

[48] Despite its toxicity at high levels, heavy water has been observed to extend lifespan of certain yeasts by up to 85%, with the hypothesized mechanism being the reduction of reactive oxygen species turnover.

[51] Experiments with mice, rats, and dogs[52] have shown that a degree of 25% deuteration prevents gametes or zygotes from developing, causing (sometimes irreversible) sterility.

Some news services were not careful to distinguish these points, and some of the public were left with the impression that heavy water is normally radioactive and more severely toxic than it actually is.

[32] An alternative process,[62] patented by Graham M. Keyser, uses lasers to selectively dissociate deuterated hydrofluorocarbons to form deuterium fluoride, which can then be separated by physical means.

Argentina was the main producer of heavy water, using an ammonia/hydrogen exchange based plant supplied by Switzerland's Sulzer company.

Argentina produced 200 short tons (180 tonnes) of heavy water per year in 2015 using the monothermal ammonia-hydrogen isotopic exchange method.

The U.S. developed the Girdler sulfide chemical exchange production process—which was first demonstrated on a large scale at the Dana, Indiana plant in 1945 and at the Savannah River Site in 1952.

[73][74] In 1934, Norsk Hydro built the first commercial heavy water plant at Vemork, Tinn, eventually producing 4 kilograms (8.8 lb) per day.

Norwegian commandos and local resistance managed to demolish small, but key parts of the electrolytic cells, dumping the accumulated heavy water down the factory drains.

[77] The German nuclear weapons program was much less advanced than the Manhattan Project, and no reactor constructed in Nazi Germany came close to reaching criticality.

[80] The Atomic Energy of Canada Limited (AECL) design of power reactor requires large quantities of heavy water to act as a neutron moderator and coolant.

Commissioning of BHWP A was done by Ontario Hydro from 1971 through 1973, with the plant entering service on 28 June 1973, and design production capacity being achieved in April 1974.

Due to the success of BHWP A and the large amount of heavy water that would be required for the large numbers of upcoming planned CANDU nuclear power plant construction projects, Ontario Hydro commissioned three additional heavy water production plants for the Bruce site (BHWP B, C, and D).

The remaining capacity continued to operate in order to fulfil demand for heavy water exports until it was permanently shut down in 1997, after which the plant was gradually dismantled and the site cleared.

Iran has indicated that the heavy-water production facility will operate in tandem with a 40 MW research reactor that had a scheduled completion date in 2009.

Under the Joint Comprehensive Plan of Action, Iran is permitted to store only 130 tonnes (140 short tons) of heavy water.

Commissioned in 1995–96, the Khushab Nuclear Complex is a central element of Pakistan's stockpile program for production of weapon-grade plutonium, deuterium, and tritium for advanced compact warheads (i.e. thermonuclear weapons).

[93] Unlike India and Iran, the heavy water produced by Pakistan is not exported nor available for purchase to any nation and is solely used for its weapons complex and energy generation at its local nuclear power plants.

Romania produced heavy water at the now-decommissioned Drobeta Girdler sulfide plant for domestic and export purposes.

[citation needed] Deuterium oxide is used in nuclear magnetic resonance spectroscopy when using water as a solvent if the nuclide of interest is hydrogen.

Other problems were the ideological aversion regarding what propaganda dismissed as "Jewish physics" and the mistrust between those who had been enthusiastic Nazis even before 1933 and those who were Mitläufer or trying to keep a low profile.

Due to its potential for use in nuclear weapons programs, the possession or import/export of large industrial quantities of heavy water are subject to government control in several countries.

In the U.S. and Canada, non-industrial quantities of heavy water (i.e., in the gram to kg range) are routinely available without special license through chemical supply dealers and commercial companies such as the world's former major producer Ontario Hydro.

This event is detected when the free neutron is absorbed by 35Cl− present from NaCl deliberately dissolved in the heavy water, causing emission of characteristic capture gamma rays.

Thus, in this experiment, heavy water not only provides the transparent medium necessary to produce and visualize Cherenkov radiation, but it also provides deuterium to detect exotic mu type (μ) and tau (τ) neutrinos, as well as a non-absorbent moderator medium to preserve free neutrons from this reaction, until they can be absorbed by an easily detected neutron-activated isotope.