Editing Heavy water (section)

==Production methods==
The most cost-effective process for producing heavy water is the dual temperature exchange sulfide process (known as the Girdler sulfide process) developed in parallel by [[Karl-Hermann Geib]] and [[Jerome S. Spevack]] in 1943.<ref name="HW">{{Cite report |title=An Early History of Heavy Water |last=Waltham |first=Chris |publisher=[[University of British Columbia]] |date=August 1998 |arxiv=physics/0206076 }}</ref> An alternative process,<ref name=":2">{{cite web|url=https://patents.google.com/patent/US4620909 |title=Method for isotope replenishment in an exchange liquid used in a laser |access-date=14 August 2010}}</ref> patented by Graham M. Keyser, uses [[lasers]] to selectively dissociate deuterated [[hydrofluorocarbons]] to form deuterium [[fluoride]], which can then be separated by physical means. Although the energy consumption for this process is much less than for the Girdler sulfide process, this method is currently uneconomical due to the expense of procuring the necessary hydrofluorocarbons.

As noted, modern commercial heavy water is almost universally referred to, and sold as, deuterium oxide. It is most often sold in various grades of purity, from 98% enrichment to 99.75–99.98% deuterium enrichment (nuclear reactor grade) and occasionally even higher isotopic purity.
{| class="wikitable"
|+Methods of heavy water production<ref name="w2152">{{cite web |title=Тяжелая вода – свойства, получение и применение в ядерной отрасли |trans-title=Heavy Water - Properties, Production, and Application in the Nuclear Industry |url=https://istina.msu.ru/conferences/presentations/110798552/ |access-date=2025-01-25 |website=ИСТИНА – Интеллектуальная Система Тематического Исследования НАукометрических данных |language=ru}}</ref>
!Method type
!First plant
!Date
!Feedstock
!Dual temperature
!Temperature (K)
!Separation coefficienct
!Energy consumption (MWh/kg)
|-
|[[Electrolysis of water|Electrolysis]]
|[[Vemork]], Norway
|1934
| colspan="2" |<chem>H2O</chem>
|360–370
|5–7
|120–150
|-
| rowspan="3" |[[Rectification (chemical/process engineering)|Rectification]]
|[[P-9 Project#Morgantown|Morgantown Ordnance Works]], United States
|1943
| colspan="2" |<chem>H2O</chem>
|353–373
|1.043–1.026
|40
|-
|[[Norilsk]], Soviet Union
|1955
| colspan="2" |<chem>NH3</chem>
|283–293
|1.024–1.020
|8
|-
|?, Soviet Union
|1958
| colspan="2" |<chem>H2</chem>
|22–23
|1.47–1.52
|4–5
|-
| rowspan="8" |Chemical isotope exchange
|
|
| colspan="2" |<chem>H2-NH3</chem>
|248
|5.3
|3.0
|-
|
|
| colspan="2" |<chem>H2 -H2O</chem>
|333
|3.14
|65–70
|-
| rowspan="2" |[[Aleksin]], Soviet Union
| rowspan="2" |1947
| rowspan="2" |<chem>H2S-H2O</chem>   
|T<sub>1</sub>
|303
|2.34
| rowspan="2" |2.8
|-
|T<sub>2</sub>
|403
|1.82
|-
|
|
| rowspan="2" |<chem>H2 -H2O</chem>
|T<sub>1</sub>
|223
|7.9
| rowspan="2" |1.0
|-
|
|
|T<sub>2</sub>
|313
|3.6
|-
|
|
| rowspan="2" |<chem>H2-NH3</chem>
|T<sub>1</sub>
|248
|5.3
| rowspan="2" |1.0
|-
|
|
|T<sub>2</sub>
|333
|2.9
|-
|Laser dissociation<ref name=":2" />
|None
|
| colspan="2" |<chem>CHF3</chem>
|323–353
|
|
|}