Sodium

Moderators & Coolants

Density: 0.968 g/cm³

Liquid sodium coolant at ~100°C. Primary coolant in sodium-cooled fast reactors (SFRs) such as EBR-II, BN-600/800, and proposed designs like Natrium.

Composition

Nuclide / Element	Fraction
Na-23	1.000000

MCNP

c Sodium (liquid, ~100°C)
c Density: 0.968 g/cm3 (use -0.968 on cell card)
m23   11023.80c  1.000000  $ Na-23

Density at ~100°C. At typical SFR operating temperature (~500°C), density is ~0.856 g/cm³. Na-23 is monoisotopic.