Using Heavy Water/D2O For Cooling A CPU

[Tanmay H. Singh]

Property	D2O (Heavy water)	HDO (Semiheavy water)	H2O (Light water)
Freezing point	3.82 °C (38.88 °F) (276.97 K)	2.04 °C (35.67 °F) (275.19 K)	0.0 °C (32 °F) (273.15 K)
Boiling point	101.4 °C (214.5 °F) (374.55 K)	100.7 °C (213.3 °F) (373.85 K)	100.0 °C (212 °F) (373.15 K)
Density at STP (g/mL)	1.1056	1.054	0.9982
Temp. of maximum density	11.6 °C	Unverified	3.98 °C[11]
Dynamic viscosity (at 20 °C, mPa·s)	1.2467	1.1248	1.0016
Surface tension (at 25 °C, N/m)	0.07187	0.07193	0.07198
Heat of fusion (kJ/mol)	6.132	6.227	6.00678
Heat of vaporisation (kJ/mol)	41.521	Unverified	40.657
pH (at 25 °C)[12]	7.44 ("pD")	7.266 ("pHD")	7.0
pKb (at 25 °C)[12]	7.44 ("pKb D2O")	Unverified	7.0
Refractive index (at 20 °C, 0.5893 μm)[13]	1.32844	Unverified	1.33335

 

Deuterium oxide is used in nuclear magnetic resonance spectroscopy when using water as solvent if the nuclide of interest is hydrogen. This is because the signal from light-water (¹H₂O) solvent molecules interfere with observing the signal from the molecule of interest dissolved in it. Deuterium has a different magnetic moment and therefore does not contribute to the ¹H-NMR signal at the hydrogen-1 resonance frequency.

For some experiments, it may be desirable to identify the labile hydrogens on a compound, that is hydrogens that can easily exchange away as H⁺ ions on some positions in a molecule. With addition of D₂O, sometimes referred to as a D₂O shake, labile hydrogens exchange away and are substituted by deuterium (²H) atoms. These positions in the molecule then do not appear in the ¹H-NMR spectrum.

 

Organic chemistry[edit]

Deuterium oxide is often used as the source of deuterium for preparing specifically labelled isotopologues of organic compounds. For example, C-H bonds adjacent to ketonic carbonyl groups can be replaced by C-D bonds, using acid or base catalysis. Trimethylsulfoxonium iodide, made from dimethyl sulfoxide and methyl iodide can be recrystallized from deuterium oxide, and then dissociated to regenerate methyl iodide and dimethyl sulfoxide, both deuterium labelled. In cases where specific double labelling by deuterium and tritium is contemplated, the researcher must be aware that deuterium oxide, depending upon age and origin, can contain some tritium.

Infrared spectroscopy[edit]

Deuterium oxide is often used instead of water when collecting FTIR spectra of proteins in solution. H₂O creates a strong band that overlaps with the amide I region of proteins. The band from D₂O is shifted away from the amide I region.

Neutron moderator[edit]

Heavy water is used in certain types of nuclear reactors, where it acts as a neutron moderator to slow down neutrons so that they are more likely to react with the fissileuranium-235 than with uranium-238, which captures neutrons without fissioning. The CANDU reactor uses this design. Light water also acts as a moderator, but because light water absorbs more neutrons than heavy water, reactors using light water for a reactor moderator must use enriched uranium rather than natural uranium, otherwise criticality is impossible. A significant fraction of outdated power reactors, such as the RBMK reactors in the USSR, were constructed using normal water for cooling but graphite as a moderator. However, the danger of graphite in power reactors (graphite fires in part led to the Chernobyl disaster) has led to the discontinuation of graphite in standard reactor designs.

Because they do not require uranium enrichment, heavy water reactors are more of a concern in regards to nuclear proliferation. The breeding and extraction of plutonium can be a relatively rapid and cheap route to building a nuclear weapon, as chemical separation of plutonium from fuel is easier than isotopic separation of U-235 from natural uranium. Among current and past nuclear weapons states, Israel, India, and North Korea^[77] first used plutonium from heavy water moderated reactors burning natural uranium, while China, South Africa and Pakistan first built weapons using highly enriched uranium.

In the U.S., however, the first experimental atomic reactor (1942), as well as the Manhattan Project Hanford production reactors that produced the plutonium for the Trinity test and Fat Man bombs, all used pure carbon (graphite) neutron moderators combined with normal water cooling pipes. They functioned with neither enriched uranium nor heavy water. Russian and British plutonium production also used graphite-moderated reactors.

There is no evidence that civilian heavy water power reactors—such as the CANDU or Atucha designs—have been used to produce military fissile materials. In nations that do not already possess nuclear weapons, nuclear material at these facilities is under IAEA safeguards to discourage any diversion.

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. Suppliers of heavy water and heavy water production technology typically apply IAEA (International Atomic Energy Agency) administered safeguards and material accounting to heavy water. (In Australia, the Nuclear Non-Proliferation (Safeguards) Act 1987.) 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.

Neutrino detector[edit]

The Sudbury Neutrino Observatory (SNO) in Sudbury, Ontario uses 1,000 tonnes of heavy water on loan from Atomic Energy of Canada Limited. The neutrino detector is 6,800 feet (2,100 m) underground in a mine, to shield it from muons produced by cosmic rays. SNO was built to answer the question of whether or not electron-type neutrinos produced by fusion in the Sun (the only type the Sun should be producing directly, according to theory) might be able to turn into other types of neutrinos on the way to Earth. SNO detects the Cherenkov radiation in the water from high-energy electrons produced from electron-type neutrinos as they undergo charged current (CC) interactions with neutrons in deuterium, turning them into protons and electrons (however, only the electrons are fast enough to produce Cherenkov radiation for detection). SNO also detects neutrino↔electron scattering (ES) events, where the neutrino transfers energy to the electron, which then proceeds to generate Cherenkov radiation distinguishable from that produced by CC events. The first of these two reactions is produced only by electron-type neutrinos, while the second can be caused by all of the neutrino flavors. The use of deuterium is critical to the SNO function, because all three "flavours" (types) of neutrinos^[78] may be detected in a third type of reaction as well, neutrino-disintegration, in which a neutrino of any type (electron, muon, or tau) scatters from a deuterium nucleus (deuteron), transferring enough energy to break up the loosely bound deuteron into a free neutron and proton via a neutral current (NC) interaction. 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.

Metabolic rate testing in physiology and biology[edit]

Main article: Doubly labeled water test

Heavy water is employed as part of a mixture with H₂¹⁸O for a common and safe test of mean metabolic rate in humans and animals undergoing their normal activities.

Tritium production[edit]

See also: Tritium § Deuterium

Tritium is the active substance in self-powered lighting and controlled nuclear fusion, its other uses including autoradiography and radioactive labeling. It is also used in nuclear weapon design for boosted fission weapons and initiators. Some tritium is created in heavy water moderated reactors when deuterium captures a neutron. This reaction has a small cross-section (probability of a single neutron-capture event) and produces only small amounts of tritium, although enough to justify cleaning tritium from the moderator every few years to reduce the environmental risk of tritium escape.

Producing a lot of tritium in this way would require reactors with very high neutron fluxes, or with a very high proportion of heavy water to nuclear fuel and very low neutron absorption by other reactor material. The tritium would then have to be recovered by isotope separation from a much larger quantity of deuterium, unlike production from lithium-6 (the present method), where only chemical separation is needed.

Deuterium's absorption cross section for thermal neutrons is 0.52 millibarns (5.2 × 10⁻³² m²; 1 barn = 10⁻²⁸ m²), while those of oxygen-16 and oxygen-17 are 0.19 and 0.24 millibarns, respectively. ¹⁷O makes up 0.038% of natural oxygen, making the overall cross section 0.28 millibarns. Therefore, in D₂O with natural oxygen, 21% of neutron captures are on oxygen, rising higher as ¹⁷O builds up from neutron capture on ¹⁶O. Also, ¹⁷O may emit an alpha particle on neutron capture, producing radioactive carbon-14.

 

It Can Cool Better Than Water It Has Higher Specific Heat Capacity It Is Used To Cool Nuclear Reactors It Is The Best Liquid For Cooling...

[Fasauceome]

It's always impressive how custom water loops seem to find new and interesting ways to become more expensive

 

[Dedayog]

Otherwise known as How to Copy and Paste Wiki Pages 101

 

Forgot to list relevant info like pricing and where to buy.

 

Per 2014 pricing....

The price of deuterium oxide (heavy water) varies immensely by purity. The best price in currently aware of for generally usable material comes from Cambridge Isotopes. They sell 1 liter (slightly more than 1kg) of material for 680USD. At that price, you'll get 99%-D, meaning that 99 out of 100 hydrogen atoms are deuteria, with 1 in 100 being hydrogen.

For 995USD, also from Cambridge Isotopes, you can get 1kg of material at 99.96%-D. 

If you want material that's even more pure, Sigma Aldrich sells the best I can find. At 376USD per 50g bottle, you will spend 7520USD for 1kg of 99.994%-D deuterium oxide.

[nick name]

I don't think its capacity is what's key to being used in a cooling loop.  Do nuclear reactors run the water through something like a radiator?  I'll have to look that up.  

 

 

[bimmerman]

Can you? Yes.

 

Will you notice a difference? Your wallet will, your CPU won't.