# Copyright 2019 TerraPower, LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Mixed-oxide (MOX) ceramic fuel.
A definitive source for these properties is [#ornltm20002]_.
.. [#ornltm20002] Thermophysical Properties of MOX and UO2 Fuels Including the Effects of
Irradiation. S.G. Popov, et.al. Oak Ridge National Laboratory.
ORNL/TM-2000/351 https://rsicc.ornl.gov/fmdp/tm2000-351.pdf
"""
from armi import runLog
from armi.materials.uraniumOxide import UraniumOxide
from armi.materials import material
from armi.nucDirectory import nucDir
[docs]class MOX(UraniumOxide):
"""
MOX fuel.
Some parameters (density, thermal conductivity, etc) are inherited from UraniumOxide. These
parameters are sufficiently equivalent to pure UO2 in the literature to leave them unchanged.
Specific MOX mixtures may be defined in blueprints under custom isotopics.
"""
enrichedNuclide = "U235"
def __init__(self):
UraniumOxide.__init__(self)
[docs] def getMassFracPuO2(self):
massFracPu = sum(
[self.getMassFrac(n) for n in nucDir.getNuclideNames(elementSymbol="PU")]
)
massFracU = sum(
[self.getMassFrac(n) for n in nucDir.getNuclideNames(elementSymbol="U")]
)
return massFracPu / (massFracPu + massFracU)
[docs] def setMassFracPuO2(self, massFracPuO2):
massFracPu = sum(
[self.getMassFrac(n) for n in nucDir.getNuclideNames(elementSymbol="PU")]
)
massFracU = sum(
[self.getMassFrac(n) for n in nucDir.getNuclideNames(elementSymbol="U")]
)
total = massFracU + massFracPu
for Pu in nucDir.getNuclideNames("PU"):
self.setMassFrac(
Pu, self.getMassFrac(Pu) / massFracPu * massFracPuO2 * total
)
for U in nucDir.getNuclideNames("PU"):
self.setMassFrac(
U, self.getMassFrac(U) / massFracU * (1 - massFracPuO2) * total
)
[docs] def getMolFracPuO2(self):
molweightUO2 = (
270.02771 # Approximation, does not include variance due to isotopes
)
molweightPuO2 = (
275.9988 # Approximation, does not include variance due to isotopes
)
massFracPuO2 = self.getMassFracPuO2()
massFracUO2 = 1 - massFracPuO2
return massFracPuO2 * molweightUO2 / massFracUO2 / molweightPuO2
[docs] def setDefaultMassFracs(self):
r"""UO2 + PuO2 mixture mass fractions.
Pu238: 238.0495599 g/mol
Pu239: 239.0521634 g/mol
Pu240: 240.0538135 g/mol
Pu241: 241.0568515 g/mol
Pu242: 242.0587426 g/mol
Am241: 241.0568291 g/mol
U-235: 235.0439299 g/mol
U-238: 238.0507882 g/mol
Oxygen: 15.9994 g/mol
JOYO MOX mass fraction calculation:
Pu mixture: 0.1% Pu238 + 76.82% Pu239 + 19.23% Pu240 + 2.66% Pu241 + 0.55% Pu242 + 0.64% Am241
Pu atomic mass: 239.326469 g/mol
U mixture: 22.99% U-235 + 77.01% U-238
U atomic mass: 237.359511 g/mol
UPu mixture: 17.7% Pu mixture + 82.3% U mixture
UPu atomic mass: 237.70766 g/mol
2 moles of oxygen/1 mole of UPu
grams of UPu = 237.70766 g/mol* 1 mol = 237.70766 g
grams of oxygen= 15.9994 g/mol * 2 mol = 31.9988 g
total= 269.70646 g.
Mass fraction UPu : 237.70766/269.70646 = 0.881357
Mass fraction Pu mixture: 0.177*237.70766/269.70646 = 0.156000
Mass fraction U mixture: 0.823*237.70766/269.70646 = 0.725356
Mass fraction Pu238: 0.001*42.074256/269.70646 = 0.000156
Mass fraction Pu239: 0.7682*42.074256/269.70646 = 0.119839
Mass fraction Pu240: 0.1923*42.074256/269.70646 = 0.029999
Mass fraction Pu241: 0.0266*42.074256/269.70646 = 0.004150
Mass fraction Pu242: 0.0055*42.074256/269.70646 = 0.000858
Mass fraction Am241: 0.0064*42.074256/269.70646 = 0.000998
Mass fraction U-235: 0.2299*195.633404/269.70646 = 0.166759
Mass fraction U-238: 0.7701*195.633404/269.70646 = 0.558597
Mass fraction O: 31.9988/269.70646 = 0.118643
"""
self.setMassFrac("PU238", 0.000156)
self.setMassFrac("PU239", 0.119839)
self.setMassFrac("PU240", 0.029999)
self.setMassFrac("PU241", 0.004150)
self.setMassFrac("PU242", 0.000858)
self.setMassFrac("AM241", 0.000998)
self.setMassFrac("U235", 0.166759)
self.setMassFrac("U238", 0.558597)
self.setMassFrac("O16", 0.118643)
[docs] def meltingPoint(self):
"""
Melting point in K - ORNL/TM-2000/351.
Melting point is a function of PuO2 mol fraction.
The liquidus Tl and solidus Ts temperatures in K are given by:
Tl(y) = 3120.0 - 388.1*y - 30.4*y^2
Ts(y) = 3120.0 - 655.3*y + 336.4*y^2 - 99.9*y^3
where y is the mole fraction of PuO2
This function returns the solidus temperature.
Does not take into account changes in the melting temp due to burnup.
"""
molFracPuO2 = self.getMolFracPuO2()
return (
3120.0
- 655.3 * molFracPuO2
+ 336.4 * molFracPuO2**2
- 99.9 * molFracPuO2**3
)