Tungtvann

Tungtvann, or heavy water, is a form of water in which the regular hydrogen atoms are replaced by the heavier isotope deuterium (D). Its chemical formula is D2O. Although chemically similar to ordinary water, heavy water has different physical properties and participates differently in certain nuclear processes.

Natural occurrence and properties

In natural water, deuterium accounts for about 0.015 percent of hydrogen. Because of the mass difference, D2O has a higher density and a higher boiling point (about 101.4°C) and freezes at around 3.8°C. It is a weaker solvent for some chemical reactions and serves as a neutron moderator in certain types of nuclear reactors.

Production and supply

Heavy water is produced in specialized facilities by separating hydrogen isotopes from water. Industrial methods include electrolysis, distillation, and catalytic exchange processes. Because it is expensive to produce, its use is typically limited to nuclear reactors and various scientific applications. Large-scale production is concentrated in countries with significant nuclear programs.

Uses

The principal use of heavy water is as a neutron moderator and coolant in certain nuclear reactors, most notably the CANDU (Canada Deuterium Uranium) design. It also serves in scientific research as a neutron source, a tracer in metabolic studies, and a solvent in some isotopic experiments. In small amounts, it is non-radioactive and posing limited radiological risk.

History

Heavy water played a strategic role during World War II because it was a key material for early nuclear research. The German program depended on heavy water shipments from Norge’s Vemork plant, which were disrupted by Allied operations. The 1943 sabotage missions significantly hindered the German goal of developing a reactor.

Safety and regulation

Heavy water is not itself radioactive. It can be biologically disruptive at high replacement levels of body water, but typical exposure poses limited risk. Standard chemical safety practices apply for handling and storage.