What is the heavy water in a nuclear reactor, is it drinkable?

There are always some weird questions in the world, such as is heavy water drinkable, and what does it taste like?
What is heavy water? Simply put, heavy water is the type of water where the hydrogen in the normal water molecule is replaced by deuterium. There are three types of hydrogen atoms in nature, hydro-1, hydro-2 and hydro-3. For remembering convenience, they are often referred to as proti, deuterium and tritium, respectively.

The main difference between these three types of hydrogen lies in the number of neutrons in the nucleus. Protium is the default type of hydrogen in our natural habitat, which consists of a proton and an electron, while deuterium has an extra neutron when compared to proti and tritium with two more neutrons when compared to proti. . Most of the hydrogen in nature exists in the form of proti, with a relative abundance of 99.9844%, while deuterium abundance is relatively low, at about 0.0156%. For tritium, since abundance is less than 0.001% it is usually noted as a trace amount. During the recent nuclear wastewater incident in Fukushima, Japan, tritium content was a major issue being discussed. Tritium is radioactive and undergoes beta decay with a half-life of 12.43 years. It is often thought that it was caused by the interactions of cosmic radiation and hydrogen in the atmosphere. Since the introduction of nuclear technology, humans have produced 5 times more natural tritium (about 7.3 kg in nature). Although proti (H2O), deuterium (D2O), and tritium (T2O) differ in atomic composition, the differences in their chemical properties are very small (D2O and T2O are commonly known as heavy water and super heavy water). Also because many of the three properties are similar, tritium is also one of the most difficult to separate and remove substances in nuclear wastewater. However, non-radioactive heavy water is much more interesting than super heavy water. Since the density of heavy water is 10% greater than that of water, heavy ice can sink to the bottom in the water. In 1931, the American scientist Harold Clayton Urey discovered the isotope of hydrogen, deuterium and he also received the Nobel Prize in Chemistry in 1934. In 1933, Urey’s mentor Gilbert Newton Lewis produced 0.5 ml of heavy water by electrolysis of water, with a purity of 65.7%. Harold Clayton Urey However, deuterium in natural water does not always exist in D2O form, and it is more likely to exist as HDO (half heavy water). During the production of heavy water by electrolysis, when the HDO molecules reach a certain rate, there will be an exchange of hydrogen ions between the water molecules, and the ratio of D2O also increases accordingly. . When the method of producing heavy water by electrolysis appeared, it quickly applied in practice. The year after Lewis produced high-purity heavy water, Norway built the Venmork hydroelectric plant in 1934, which uses nature’s abundant water to electrolyze water, creating hydrogen for production. Nitrate fertilizers. Norway’s Venmork hydroelectric plant. However, the manufacture of chemical fertilizers requires hydrogen from electrolytic water, and does not use the heavy water remaining in the electrolysis cell. So after a period of operation, the plant analyzed the residue of electrolysis and found that the ratio of deuterium to hydrogen (protium) was 1:48, much higher than the natural ratio 1. : 6400, though most of them exist in semi-HDO form. So the Norwegian Hydropower Company accepted the request of the person in charge of the hydrogen plant to produce heavy water from the byproducts of electrolysis. Therefore, it can be said that Norwegian Hydropower has become the earliest heavy water supplier in the scientific community. However, the story of heavy water has only just begun. In late 1938, the Germans discovered that the bombardment of a neutron on uranium could cause nuclear fission. In late 1939, the Soviet Union concluded that heavy water and graphite were the only viable regulators for uranium reactors, and each of these reactors required about 15 tons of heavy water to function. So heavy water then became a strategic substance because it can slow down the neutrons produced by chain nuclear reactions, and all nations take it seriously. From 1940 to World War II, the Norwegian heavy water plant was under Nazi control and bought nearly all of the heavy water in bulk. Allied forces crossed the mountain plateau to destroy heavy water factories under Nazi control. In short, when heavy water first appeared was associated with nuclear reactions, many people’s first impression of it was extremely dangerous, but it was not. Right after the discovery of heavy water, scientists were curious about it, so someone drank heavy water right after the discovery of deuterium. GeorgeCharles de Hevesy and Harold Clayton Urey, who discovered the deuterium, were good friends. In 1934, Hevesy asked Urey to get several liters of heavy water with low purity, only 0.6%. Hevesy then drank this heavy water to use deuterium as a marker, studied the water metabolism of the human body, and eventually concluded that the average residence time of water molecules in the muscle. human body is 13 ± 1.5 days. But if absorbing the amount of heavy water with a higher purity, it will have a significant effect on the body of animals and plants. Plants will die in high concentrations of heavy water. Animals such as mice and dogs will become infertile if D2O reaches more than 25% in the body, and fish will die rapidly in water that is more than 90% heavier. Mammals will die about a week after being given about 50% heavy water. In fact, humans and animals can hardly be exposed to such high purity heavy water, except animals raised for research purposes.