Uranium Nitride

Fuels

Density: 14.31 g/cm³

Atom density: 0.068404 atoms/b·cm

Uranium mononitride at 3 wt% U-235. High uranium density and high thermal conductivity make it attractive for advanced and space reactors.

Where these numbers come from

PNNL-15870 Rev. 2, "Uranium Nitride" (id uranium-nitride): density and full isotopic composition are taken from the compendium unchanged.

Open the compendium entry for the isotope-by-isotope table and the compendium's own notes.

Material compositions from PNNL-15870 Rev. 2 (April 2021), R.S. Detwiler, R.J. McConn Jr., T.F. Grimes, S.A. Upton, and E.J. Engel, Compendium of Material Composition Data for Radiation Transport Modeling, Pacific Northwest National Laboratory. Full report (DOI 10.2172/1782721)

Composition

Nuclide (ZAID)	Weight fraction	Atom fraction	Atom density (atoms/b·cm)
N-14 (7014)	5.5373e-2	4.9818e-1	3.4077e-2
N-15 (7015)	2.1670e-4	1.8200e-3	1.2449e-4
U-234 (92234)	2.5216e-4	1.3573e-4	9.2847e-6
U-235 (92235)	2.8332e-2	1.5186e-2	1.0388e-3
U-236 (92236)	1.3033e-4	6.9559e-5	4.7581e-6
U-238 (92238)	9.1570e-1	4.8461e-1	3.3149e-2

This is the material as formulated. The cards below carry weight fractions, written negative, which is what MCNP and Serpent read as a mass basis.

Generated material cards

MCNP

c Uranium Nitride
c PNNL-15870 Rev. 2, "Uranium Nitride" - reactormc.net/nrdp/material/un; rho =
c 14.31 g/cm3 (use -14.31 on the cell card)
m6    7014.80c  -0.055373  $ N14
      7015.80c  -2.1670e-4  $ N15
      92234.80c  -2.5216e-4  $ U234
      92235.80c  -0.028332  $ U235
      92236.80c  -1.3033e-4  $ U236
      92238.80c  -0.915695  $ U238

MCNP and Serpent cards use .80c (ENDF/B-VII.1 at 293.6 K) — renumber m1 and change the suffix to match your deck. SCONE compositions are atom densities in atoms/barn-cm with the .03 suffix matching temp 300. See the library reference before changing a suffix: the mapping is not portable between vendors.

Notes

N-15 enrichment is sometimes used to suppress the parasitic N-14(n,p)C-14 reaction — replace the N-14 row with 7015 if you are modelling it. Enrichment here is the compendium's 3 wt%; scale the uranium rows for a different one.

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