Helium

He

Moderators & Coolants

Density: 0.000164 g/cm³

Helium gas at STP. Coolant in high-temperature gas-cooled reactors (HTGR, VHTR) and fuel-cladding gap fill gas.

Composition

Nuclide / ElementFraction
He-41.000000

Code output

MCNP
c Helium Gas (STP)
c Density: 0.000164 g/cm3 (use -0.000164 on cell card)
m27    2004.80c  1.000000  $ He-4

SCONE reads ACE libraries: build nuclearData.materials entries from these nuclides using ZAID plus a temperature/table suffix that exists in your aceLibrary, with number densities in atoms/barn-cm. See the SCONE nuclear data tutorial and the NRDP library reference.

Notes

Density at STP. HTGR helium coolant operates at ~7 MPa, where density is ~3.8 kg/m³. Also used as fill gas in fuel-cladding gaps.

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