resolving first round of @paulromano comments

docs/source/io_formats/nuclear_data.rst

@@ -16,18 +16,17 @@ Incident Neutron Data
              - **metastable** (*int*) -- Metastable state (0=ground, 1=first
                excited, etc.)
              - **atomic_weight_ratio** (*double*) -- Mass in units of neutron masses
-             - **kTs** (*double[]*) -- Temperatures (in MeV) contained in the library
              - **n_reaction** (*int*) -- Number of reactions
 
 :Datasets: - **energy** (*double[]*) -- Energy points at which cross sections are tabulated
 
 **/<nuclide name>/kTs/**
 
-<TTTK> is the temperature in Kelvin, rounded to the nearest integer, of the
+<TTT>K is the temperature in Kelvin, rounded to the nearest integer, of the
 temperature-dependent data set.  For example, the data set corresponding to
 300 Kelvin would be located at `300K`.
 
-:Datasets: - **<TTTK>** (*double[]*) -- kT values (in MeV) for each Temperature
+:Datasets: - **<TTT>K** (*double*) -- kT values (in MeV) for each Temperature
    TTT (in Kelvin)
 
 **/<nuclide name>/reactions/reaction_<mt>/**
@@ -39,9 +38,9 @@ temperature-dependent data set.  For example, the data set corresponding to
                scattering is center-of-mass (1) or laboratory (0)
              - **n_product** (*int*) -- Number of reaction products
 
-**/<nuclide name>/reactions/reaction_<mt>/<TTTK>/**
+**/<nuclide name>/reactions/reaction_<mt>/<TTT>K/**
 
-<TTTK> is the temperature in Kelvin, rounded to the nearest integer, of the
+<TTT>K is the temperature in Kelvin, rounded to the nearest integer, of the
 temperature-dependent data set.  For example, the data set corresponding to
 300 Kelvin would be located at `300K`.
 
@@ -116,9 +115,9 @@ Thermal Neutron Scattering Data
                outgoing angle-energy distributions are represented ('equal',
                'skewed', or 'continuous').
 
-**/<thermal name>/elastic/<TTTK>/**
+**/<thermal name>/elastic/<TTT>K/**
 
-<TTTK> is the temperature in Kelvin, rounded to the nearest integer, of the
+<TTT>K is the temperature in Kelvin, rounded to the nearest integer, of the
 temperature-dependent data set.  For example, the data set corresponding to
 300 Kelvin would be located at `300K`.
 
@@ -128,9 +127,9 @@ temperature-dependent data set.  For example, the data set corresponding to
              and angles for coherent elastic scattering for temperature TTT
              (in Kelvin)
 
-**/<thermal name>/inelastic/<TTTK>/**
+**/<thermal name>/inelastic/<TTT>K/**
 
-<TTTK> is the temperature in Kelvin, rounded to the nearest integer, of the
+<TTT>K is the temperature in Kelvin, rounded to the nearest integer, of the
 temperature-dependent data set.  For example, the data set corresponding to
 300 Kelvin would be located at `300K`.
 

openmc/data/data.py

@@ -219,6 +219,7 @@ def atomic_mass(isotope):
 
     return _ATOMIC_MASS.get(isotope.lower())
 
-def kT_to_K(kT):
-    K = kT / 8.6173324e-11
-    return K
+# The value of the Boltzman constant in units of MeV / K
+# Values here are from the Committee on Data for Science and Technology
+# (CODATA) 2010 recommendation (doi:10.1103/RevModPhys.84.1527).
+K_BOLTZMANN = 8.6173324E-11

openmc/data/neutron.py

@@ -7,7 +7,7 @@ from warnings import warn
 import numpy as np
 import h5py
 
-from .data import ATOMIC_SYMBOL, SUM_RULES, kT_to_K
+from .data import ATOMIC_SYMBOL, SUM_RULES, K_BOLTZMANN
 from .ace import Table, get_table
 from .fission_energy import FissionEnergyRelease
 from .function import Tabulated1D, Sum
@@ -40,6 +40,16 @@ def _get_metadata(zaid, metastable_scheme='nndc'):
 
     Returns
     -------
+    name : str
+        Name of the table
+    element : str
+        The atomic symbol of the isotope in the table; e.g., Zr.
+    Z : int
+        Number of protons in the nucleus
+    mass_number : int
+        Number of nucleons in the nucleus
+    metastable : int
+        Metastable state of the nucleus. A value of zero indicates ground state.
 
     """
 
@@ -98,7 +108,7 @@ class IncidentNeutron(EqualityMixin):
         Metastable state of the nucleus. A value of zero indicates ground state.
     atomic_weight_ratio : float
         Atomic mass ratio of the target nuclide.
-    kTs : Iterable float
+    kTs : Iterable of float
         List of temperatures of the target nuclide in the data set.
         The temperatures have units of MeV.
 
@@ -112,7 +122,7 @@ class IncidentNeutron(EqualityMixin):
         Atomic weight ratio of the target nuclide.
     energy : dict of numpy.ndarray
         The energy values (MeV) at which reaction cross-sections are tabulated.
-        They keys of the dict are the temperature string ('296.3K') for each
+        They keys of the dict are the temperature string ('294K') for each
         set of energies
     fission_energy : None or openmc.data.FissionEnergyRelease
         The energy released by fission, tabulated by component (e.g. prompt
@@ -122,7 +132,7 @@ class IncidentNeutron(EqualityMixin):
     metastable : int
         Metastable state of the nucleus. A value of zero indicates ground state.
     name : str
-        ZAID identifier of the table, e.g. 92235.70c.
+        ZAID identifier of the table, e.g. 92235.
     reactions : collections.OrderedDict
         Contains the cross sections, secondary angle and energy distributions,
         and other associated data for each reaction. The keys are the MT values
@@ -132,8 +142,8 @@ class IncidentNeutron(EqualityMixin):
         are the MT values and the values are Reaction objects.
     temperatures : Iterable of str
         List of string representations the temperatures of the target nuclide
-        in the data set.  The temperatures are strings with 1 decimal place,
-        i.e., '293.6K'
+        in the data set.  The temperatures are strings of the temperature,
+        rounded to the nearest integer; e.g., '294K'
     kTs : Iterable of float
         List of temperatures of the target nuclide in the data set.
         The temperatures have units of MeV.
@@ -150,7 +160,8 @@ class IncidentNeutron(EqualityMixin):
         self.metastable = metastable
         self.atomic_weight_ratio = atomic_weight_ratio
         self.kTs = kTs
-        self.temperatures = [str(int(round(kT_to_K(kT)))) + "K" for kT in kTs]
+        self.temperatures = [str(int(round(kT / K_BOLTZMANN))) + "K"
+                             for kT in kTs]
         self.energy = {}
         self._fission_energy = None
         self.reactions = OrderedDict()
@@ -300,7 +311,7 @@ class IncidentNeutron(EqualityMixin):
         if ace.temperature not in self.kTs:
             if name == self.name:
                 # Add temperature and kTs
-                strT = str(int(round(kT_to_K(ace.temperature)))) + "K"
+                strT = str(int(round(ace.temperature / K_BOLTZMANN))) + "K"
                 self.temperatures.append(strT)
                 self.kTs.append(ace.temperature)
                 # Read energy grid
@@ -463,7 +474,7 @@ class IncidentNeutron(EqualityMixin):
         kTs = []
         for temp in kTg:
             kTs.append(kTg[temp].value)
-        temperatures = [str(int(round(kT_to_K(kT)))) + "K" for kT in kTs]
+        temperatures = [str(int(round(kT / K_BOLTZMANN))) + "K" for kT in kTs]
 
         data = cls(name, atomic_number, mass_number, metastable,
                    atomic_weight_ratio, kTs)
@@ -550,7 +561,7 @@ class IncidentNeutron(EqualityMixin):
         # Assign temperature to the running list
         kTs = [ace.temperature]
 
-        temperatures = [str(int(round(kT_to_K(ace.temperature)))) + "K"]
+        temperatures = [str(int(round(ace.temperature / K_BOLTZMANN))) + "K"]
 
         # If mass number hasn't been specified, make an educated guess
         zaid, xs = ace.name.split('.')

openmc/data/reaction.py

@@ -12,7 +12,7 @@ from openmc.stats import Uniform
 from .angle_distribution import AngleDistribution
 from .angle_energy import AngleEnergy
 from .function import Tabulated1D, Polynomial
-from .data import REACTION_NAME, kT_to_K
+from .data import REACTION_NAME, K_BOLTZMANN
 from .product import Product
 from .uncorrelated import UncorrelatedAngleEnergy
 
@@ -444,8 +444,10 @@ class Reaction(EqualityMixin):
             HDF5 group to write to
         energy : Iterable of float
             Array of energies at which cross sections are tabulated at
-        temperatures : Iterable of float
-            Array of temperatures at which to obtain the cross sections
+        temperatures : Iterable of str
+            List of string representations the temperatures of the target
+            nuclide in the data set.  The temperatures are strings of the
+            temperature, rounded to the nearest integer; e.g., '294K'
 
         Returns
         -------
@@ -488,7 +490,7 @@ class Reaction(EqualityMixin):
 
         # Convert data temperature to a "300.0K" number for indexing
         # temperature data
-        strT = str(int(round(kT_to_K(ace.temperature)))) + "K"
+        strT = str(int(round(ace.temperature / K_BOLTZMANN))) + "K"
 
         if i_reaction > 0:
             mt = int(ace.xss[ace.jxs[3] + i_reaction - 1])

openmc/data/thermal.py

@@ -8,7 +8,7 @@ import h5py
 
 import openmc.checkvalue as cv
 from openmc.mixin import EqualityMixin
-from .data import kT_to_K
+from .data import K_BOLTZMANN
 from .ace import Table, get_table
 from .angle_energy import AngleEnergy
 from .function import Tabulated1D
@@ -177,8 +177,8 @@ class ThermalScattering(EqualityMixin):
         Name of the table, e.g. lwtr.20t.
     temperatures : Iterable of str
         List of string representations the temperatures of the target nuclide
-        in the data set.  The temperatures are strings with 1 decimal place,
-        i.e., '293.6K'
+        in the data set.  The temperatures are strings of the temperature,
+        rounded to the nearest integer; e.g., '294K'
     kTs : Iterable of float
         List of temperatures of the target nuclide in the data set.
         The temperatures have units of MeV.
@@ -191,7 +191,8 @@ class ThermalScattering(EqualityMixin):
         self.name = name
         self.atomic_weight_ratio = atomic_weight_ratio
         self.kTs = kTs
-        self.temperatures = [str(int(round(kT_to_K(kT)))) + "K" for kT in kTs]
+        self.temperatures = [str(int(round(kT / K_BOLTZMANN))) + "K"
+                             for kT in kTs]
         self.elastic_xs = {}
         self.elastic_mu_out = {}
         self.inelastic_xs = {}
@@ -304,7 +305,7 @@ class ThermalScattering(EqualityMixin):
         if ace.temperature not in self.kTs:
             if name == self.name:
                 # Add temperature and kTs
-                strT = str(int(round(kT_to_K(ace.temperature)))) + "K"
+                strT = str(int(round(ace.temperature / K_BOLTZMANN))) + "K"
                 self.temperatures.append(strT)
                 self.kTs.append(ace.temperature)
 
@@ -442,7 +443,7 @@ class ThermalScattering(EqualityMixin):
         kTs = []
         for temp in kTg:
             kTs.append(kTg[temp].value)
-        temperatures = [str(int(round(kT_to_K(kT)))) + "K" for kT in kTs]
+        temperatures = [str(int(round(kT / K_BOLTZMANN))) + "K" for kT in kTs]
 
         table = cls(name, atomic_weight_ratio, kTs)
         table.zaids = group.attrs['zaids']
@@ -530,7 +531,7 @@ class ThermalScattering(EqualityMixin):
 
         # Assign temperature to the running list
         kTs = [ace.temperature]
-        temperatures = [str(int(round(kT_to_K(ace.temperature)))) + "K"]
+        temperatures = [str(int(round(ace.temperature / K_BOLTZMANN))) + "K"]
 
         table = cls(name, ace.atomic_weight_ratio, kTs)