Resonace Covariance Module

docs/source/examples/index.rst

@@ -24,6 +24,7 @@ Basic Usage
     triso
     candu
     nuclear-data
+    nuclear-data-resonance-covariance
 
 ------------------------------------
 Multi-Group Cross Section Generation

docs/source/examples/nuclear-data-resonance-covariance.rst

@@ -0,0 +1,13 @@
+.. _notebook_nuclear_data_resonance_covariance:
+
+==================================
+Nuclear Data: Resonance Covariance
+==================================
+
+.. only:: html
+
+    .. notebook:: ../../../examples/jupyter/nuclear-data-resonance-covariance.ipynb
+
+.. only:: latex
+
+    IPython notebooks must be viewed in the online HTML documentation.

docs/source/pythonapi/data.rst

@@ -79,6 +79,11 @@ Resonance Data
     openmc.data.MultiLevelBreitWigner
     openmc.data.ReichMoore
     openmc.data.RMatrixLimited
+    openmc.data.ResonanceCovariances
+    openmc.data.ResonanceCovarianceRange
+    openmc.data.SingleLevelBreitWignerCovariance
+    openmc.data.MultiLevelBreitWignerCovariance
+    openmc.data.ReichMooreCovariance
     openmc.data.ParticlePair
     openmc.data.SpinGroup
     openmc.data.Unresolved

openmc/data/__init__.py

@@ -27,5 +27,6 @@
 from .library import *
 from .fission_energy import *
 from .resonance import *
+from .resonance_covariance import *
 from .multipole import *
 from .grid import *

openmc/data/endf.py

@@ -71,6 +71,24 @@ def float_endf(s):
     return float(_ENDF_FLOAT_RE.sub(r'\1e\2', s))
 
 
+def _int_endf(s):
+    """Convert string to int. Used for INTG records where blank entries
+    indicate a 0.
+
+    Parameters
+    ----------
+    s : str
+        Integer or spaces
+
+    Returns
+    -------
+    integer
+        The number or 0
+    """
+    s = s.strip()
+    return int(s) if s else 0
+
+
 def get_text_record(file_obj):
     """Return data from a TEXT record in an ENDF-6 file.
 
@@ -250,6 +268,50 @@ def get_tab2_record(file_obj):
     return params, Tabulated2D(breakpoints, interpolation)
 
 
+def get_intg_record(file_obj):
+    """
+    Return data from an INTG record in an ENDF-6 file. Used to store the
+    covariance matrix in a compact format.
+
+    Parameters
+    ----------
+    file_obj : file-like object
+        ENDF-6 file to read from
+
+    Returns
+    -------
+    numpy.ndarray
+        The correlation matrix described in the INTG record
+    """
+    # determine how many items are in list and NDIGIT
+    items = get_cont_record(file_obj)
+    ndigit = int(items[2])
+    npar = int(items[3])    # Number of parameters
+    nlines = int(items[4])  # Lines to read
+    NROW_RULES = {2: 18, 3: 12, 4: 11, 5: 9, 6: 8}
+    nrow = NROW_RULES[ndigit]
+
+    # read lines and build correlation matrix
+    corr = np.identity(npar)
+    for i in range(nlines):
+        line = file_obj.readline()
+        ii = _int_endf(line[:5]) - 1  # -1 to account for 0 indexing
+        jj = _int_endf(line[5:10]) - 1
+        factor = 10**ndigit
+        for j in range(nrow):
+            if jj+j >= ii:
+                break
+            element = _int_endf(line[11+(ndigit+1)*j:11+(ndigit+1)*(j+1)])
+            if element > 0:
+                corr[ii, jj] = (element+0.5)/factor
+            elif element < 0:
+                corr[ii, jj] = (element-0.5)/factor
+
+    # Symmetrize the correlation matrix
+    corr = corr + corr.T - np.diag(corr.diagonal())
+    return corr
+
+
 def get_evaluations(filename):
     """Return a list of all evaluations within an ENDF file.
 
@@ -288,7 +350,7 @@ class Evaluation(object):
     Attributes
     ----------
     info : dict
-        Miscallaneous information about the evaluation.
+        Miscellaneous information about the evaluation.
     target : dict
         Information about the target material, such as its mass, isomeric state,
         whether it's stable, and whether it's fissionable.

openmc/data/neutron.py

@@ -24,6 +24,7 @@
 from .product import Product
 from .reaction import Reaction, _get_photon_products_ace
 from . import resonance as res
+from . import resonance_covariance as res_cov
 from .urr import ProbabilityTables
 import openmc.checkvalue as cv
 from openmc.mixin import EqualityMixin
@@ -148,6 +149,8 @@ class IncidentNeutron(EqualityMixin):
         and the values are Reaction objects.
     resonances : openmc.data.Resonances or None
         Resonance parameters
+    resonance_covariance : openmc.data.ResonanceCovariance or None
+        Covariance for resonance parameters
     summed_reactions : collections.OrderedDict
         Contains summed cross sections, e.g., the total cross section. The keys
         are the MT values and the values are Reaction objects.
@@ -228,6 +231,10 @@ def reactions(self):
     def resonances(self):
         return self._resonances
 
+    @property
+    def resonance_covariance(self):
+        return self._resonance_covariance
+
     @property
     def summed_reactions(self):
         return self._summed_reactions
@@ -289,6 +296,12 @@ def resonances(self, resonances):
         cv.check_type('resonances', resonances, res.Resonances)
         self._resonances = resonances
 
+    @resonance_covariance.setter
+    def resonance_covariance(self, resonance_covariance):
+        cv.check_type('resonance covariance', resonance_covariance,
+                      res_cov.ResonanceCovariances)
+        self._resonance_covariance = resonance_covariance
+
     @summed_reactions.setter
     def summed_reactions(self, summed_reactions):
         cv.check_type('summed reactions', summed_reactions, Mapping)
@@ -744,7 +757,7 @@ def from_ace(cls, ace_or_filename, metastable_scheme='nndc'):
         return data
 
     @classmethod
-    def from_endf(cls, ev_or_filename):
+    def from_endf(cls, ev_or_filename, covariance=False):
         """Generate incident neutron continuous-energy data from an ENDF evaluation
 
         Parameters
@@ -753,6 +766,10 @@ def from_endf(cls, ev_or_filename):
             ENDF evaluation to read from. If given as a string, it is assumed to
             be the filename for the ENDF file.
 
+        covariance : bool
+            Flag to indicate whether or not covariance data from File 32 should be
+            retrieved
+
         Returns
         -------
         openmc.data.IncidentNeutron
@@ -784,6 +801,11 @@ def from_endf(cls, ev_or_filename):
         if (2, 151) in ev.section:
             data.resonances = res.Resonances.from_endf(ev)
 
+        if (32, 151) in ev.section and covariance:
+            data.resonance_covariance = (
+                res_cov.ResonanceCovariances.from_endf(ev, data.resonances)
+            )
+
         # Read each reaction
         for mf, mt, nc, mod in ev.reaction_list:
             if mf == 3:

openmc/data/resonance.py

@@ -16,6 +16,7 @@
     _reconstruct = False
 import openmc.checkvalue as cv
 
+
 class Resonances(object):
     """Resolved and unresolved resonance data