## Density of Uranium

**Uranium** is a naturally-occurring chemical element with atomic number 92 which means there are 92 protons and 92 electrons in the atomic structure. **Natural uranium** consists primarily of isotope ^{238}U (99.28%), therefore the atomic mass of uranium element is close to the atomic mass of ^{238}U isotope (238.03u). Natural uranium also consists of two other isotopes: ^{235}U (0.71%) and ^{234}U (0.0054%). Uranium has the highest atomic weight of the primordially occurring elements. Uranium metal has a very high density of **19.1 g/cm ^{3}**, denser than lead (11.3 g/cm

^{3}), but slightly less dense than tungsten and gold (19.3 g/cm

^{3}).

Uranium metal is one of the densest materials found on earth:

- Osmium – 22.6 x 10
^{3}kg/m^{3} - Iridium – 22.4 x 10
^{3}kg/m^{3} - Platinum – 21.5 x 10
^{3}kg/m^{3} - Rhenium – 21.0 x 10
^{3}kg/m^{3} - Plutonium – 19.8 x 10
^{3}kg/m^{3} - Gold – 19.3 x 10
^{3}kg/m^{3} - Tungsten – 19.3 x 10
^{3}kg/m^{3} - Uranium – 18.8 x 10
^{3}kg/m^{3} - Tantalum – 16.6 x 10
^{3}kg/m^{3} - Mercury – 13.6 x 10
^{3}kg/m^{3} - Rhodium – 12.4 x 10
^{3}kg/m^{3} - Thorium – 11.7 x 10
^{3}kg/m^{3} - Lead – 11.3 x 10
^{3}kg/m^{3} - Silver – 10.5 x 10
^{3}kg/m^{3}

But most of LWRs use the **uranium fuel**, which is in the form of **uranium dioxide**. Uranium dioxide is a black semiconducting solid with very low thermal conductivity. On the other hand the uranium dioxide has very high melting point and has well known behavior.

Uranium dioxide has significantly lower density than uranium in the metal form. Uranium dioxide has a density of **10.97 g/cm ^{3}**, but this value may vary with fuel burnup, because at low burnup densification of pellets can occurs and at higher burnup swelling occurs.

We hope, this article, **Density of Uranium**, helps you. If so, **give us a like** in the sidebar. Main purpose of this website is to help the public to learn some interesting and important information about thermal engineering.