Refractive Index Measurement of Heavy Water

Deuterium oxide, also known as heavy water, is used as a moderator in nuclear power plants to maintain the nuclear chain reaction. The purity and concentration of heavy water can be analyzed with refractive index measurement.

Heavy water in research and nuclear power plants

Heavy water is used in about 5 % of all nuclear reactors as a neutron moderator to maintain a nuclear chain reaction in heavy water reactors. Apart from that it is used in research as solvent in nuclear magnetic resonance (NMR) spectroscopy.

In heavy water, hydrogen is replaced by deuterium, a heavier isotope of hydrogen with an additional neutron in its core. The name "heavy water" derives from the approximately 11 % higher density of deuterium oxide compared to hydrogen oxide.

Except for density and pH, deuterium oxide and hydrogen oxide differ slightly in their chemical and physical properties. As they have different refractive indices, refractive index measurement allows for fast and accurate determination of purity and concentration. Testing waste water for the presence of deuterium oxide, for example, helps to ensure the primary coolant system of a reactor is not leaking.

Heavy Water Analysis with Abbemat Refractometers

Highly accurate determination of refractive indices may be used for concentration and purity meas-urements of heavy water within the reactor, as well as for waste water control in heavy water reactors. The refractive indices of hydrogen oxide and deuterium oxide differ by approximately 0.004 nD at 598.3 nm wavelength. Anton Paar´s Abbemat refractometers operate with an accuracy of up to  2 * 10-5 nD, allowing highly precise determination of deuterium oxide concentrations in aqueous solutions as ac-curate as 0.44 %. 

Learn more about Abbemat Refractometers

Other relevant instruments

Anton Paar offers a pH module and a sample changer. They allow automated filling of the sample and parallel determination of pH values and refractive indices in combination with the Abbemat 350 and 550.

Good to know

Pressurized heavy water reactors are operated all over the world, with the majority of them being op-erated in India and Canada.