Merge pull request #673 from nelsonag/aniso

Set MG mode to convert Legendre-expanded anisotropic scattering data in to tabular data by default

docs/source/usersguide/mgxs_library.rst

@@ -171,9 +171,9 @@ attributes/sub-elements required to describe the meta-data:
     provided via the ``scatt_type`` element above, is represented and thus used
     during the scattering process.  Specifically, the options are to either
     convert the Legendre expansion to a tabular representation or leave it as
-    a set of Legendre coefficients.  Converting to a tabular representation will
-    cost memory but can allow for a decrease in runtime compared to leaving as a
-    set of Legendre coefficients.  This element has the following
+    a set of Legendre coefficients.  Converting to a tabular representation
+    will cost memory but can allow for a decrease in runtime compared to
+    leaving as a set of Legendre coefficients.  This element has the following
     attributes/sub-elements:
 
     :enable:
@@ -181,7 +181,7 @@ attributes/sub-elements required to describe the meta-data:
       tabular format should be performed or not.  A value of "true" means
       the conversion should be performed, "false" means it should not.
 
-      *Default*: "false"
+      *Default*: "true"
 
     :num_points:
       If the conversion is to take place the number of tabular points is

openmc/mgxs/library.py

@@ -753,7 +753,8 @@ class Library(object):
         return pickle.load(open(full_filename, 'rb'))
 
     def get_xsdata(self, domain, xsdata_name, nuclide='total', xs_type='macro',
-                   xs_id='1m', order=None):
+                   xs_id='1m', order=None, tabular_legendre=None,
+                   tabular_points=33):
         """Generates an openmc.XSdata object describing a multi-group cross section
         data set for eventual combination in to an openmc.MGXSLibrary object
         (i.e., the library).
@@ -773,9 +774,22 @@ class Library(object):
             nuclide this will be set to 'macro' regardless.
         xs_ids : str
             Cross section set identifier. Defaults to '1m'.
-        order : Scattering order for this data entry.  Default is None,
+        order : int
+            Scattering order for this data entry.  Default is None,
             which will set the XSdata object to use the order of the
             Library.
+        tabular_legendre : None or bool
+            Flag to denote whether or not the Legendre expansion of the
+            scattering angular distribution is to be converted to a tabular
+            representation by OpenMC.  A value of `True` means that it is to be
+            converted while a value of `False` means that it will not be.
+            Defaults to `None` which leaves the default behavior of OpenMC in
+            place (the distribution is converted to a tabular representation).
+        tabular_points : int
+            This parameter is not used unless the ``tabular_legendre``
+            parameter is set to `True`.  In this case, this parameter sets the
+            number of equally-spaced points in the domain of [-1,1] to be used
+            in building the tabular distribution. Default is `33`.
 
         Returns
         -------
@@ -804,6 +818,10 @@ class Library(object):
         if order is not None:
             cv.check_greater_than('order', order, 0, equality=True)
             cv.check_less_than('order', order, 10, equality=True)
+        cv.check_type('tabular_legendre', tabular_legendre,
+                      (type(None), bool))
+        if tabular_points is not None:
+            cv.check_greater_than('tabular_points', tabular_points, 1)
 
         # Make sure statepoint has been loaded
         if self._sp_filename is None:
@@ -830,6 +848,11 @@ class Library(object):
             # the provided order or the Library's order.
             xsdata.order = min(order, self.legendre_order)
 
+        # Set the tabular_legendre option if needed
+        if tabular_legendre is not None:
+            xsdata.tabular_legendre = {'enable': tabular_legendre,
+                                       'num_points': tabular_points}
+
         if nuclide is not 'total':
             xsdata.zaid = self._nuclides[nuclide][0]
             xsdata.awr = self._nuclides[nuclide][1]
@@ -906,7 +929,8 @@ class Library(object):
         return xsdata
 
     def create_mg_library(self, xs_type='macro', xsdata_names=None,
-                          xs_ids=None):
+                          xs_ids=None, tabular_legendre=None,
+                          tabular_points=33):
         """Creates an openmc.MGXSLibrary object to contain the MGXS data for the
         Multi-Group mode of OpenMC.
 
@@ -923,6 +947,18 @@ class Library(object):
             Cross section set identifier (i.e., '71c') for all
             data sets (if only str) or for each individual one
             (if iterable of str). Defaults to '1m'.
+        tabular_legendre : None or bool
+            Flag to denote whether or not the Legendre expansion of the
+            scattering angular distribution is to be converted to a tabular
+            representation by OpenMC.  A value of `True` means that it is to be
+            converted while a value of `False` means that it will not be.
+            Defaults to `None` which leaves the default behavior of OpenMC in
+            place (the distribution is converted to a tabular representation).
+        tabular_points : int
+            This parameter is not used unless the ``tabular_legendre``
+            parameter is set to `True`.  In this case, this parameter sets the
+            number of equally-spaced points in the domain of [-1,1] to be used
+            in building the tabular distribution. Default is `33`.
 
         Returns
         -------
@@ -983,13 +1019,16 @@ class Library(object):
                     xsdata_name += '_' + nuclide
 
                 xsdata = self.get_xsdata(domain, xsdata_name, nuclide=nuclide,
-                                         xs_type=xs_type, xs_id=xs_ids[i])
+                                         xs_type=xs_type, xs_id=xs_ids[i],
+                                         tabular_legendre=tabular_legendre,
+                                         tabular_points=tabular_points)
 
                 mgxs_file.add_xsdata(xsdata)
 
         return mgxs_file
 
-    def create_mg_mode(self, xsdata_names=None, xs_ids=None):
+    def create_mg_mode(self, xsdata_names=None, xs_ids=None,
+                       tabular_legendre=None, tabular_points=33):
         """Creates an openmc.MGXSLibrary object to contain the MGXS data for the
         Multi-Group mode of OpenMC as well as the associated openmc.Materials
         and openmc.Geometry objects. The created Geometry is the same as that
@@ -1007,6 +1046,18 @@ class Library(object):
             Cross section set identifier (i.e., '71c') for all
             data sets (if only str) or for each individual one
             (if iterable of str). Defaults to '1m'.
+        tabular_legendre : None or bool
+            Flag to denote whether or not the Legendre expansion of the
+            scattering angular distribution is to be converted to a tabular
+            representation by OpenMC.  A value of `True` means that it is to be
+            converted while a value of `False` means that it will not be.
+            Defaults to `None` which leaves the default behavior of OpenMC in
+            place (the distribution is converted to a tabular representation).
+        tabular_points : int
+            This parameter is not used unless the ``tabular_legendre``
+            parameter is set to `True`.  In this case, this parameter sets the
+            number of equally-spaced points in the domain of [-1,1] to be used
+            in building the tabular distribution. Default is `33`.
 
         Returns
         -------
@@ -1071,7 +1122,9 @@ class Library(object):
 
             # Create XSdata and Macroscopic for this domain
             xsdata = self.get_xsdata(domain, xsdata_name, nuclide='total',
-                                     xs_type=xs_type, xs_id=xs_ids[i])
+                                     xs_type=xs_type, xs_id=xs_ids[i],
+                                     tabular_legendre=tabular_legendre,
+                                     tabular_points=tabular_points)
             mgxs_file.add_xsdata(xsdata)
             macroscopic = openmc.Macroscopic(name=xsdata_name, xs=xs_ids[i])
 

openmc/mgxs_library.py

@@ -445,7 +445,7 @@ class XSdata(object):
             raise ValueError(msg)
         if 'num_points' in tabular_legendre:
             num_points = tabular_legendre['num_points']
-            check_value('num_points', num_points, Integral)
+            check_type('num_points', num_points, Integral)
             check_greater_than('num_points', num_points, 0)
         else:
             if not enable:

src/mgxs_header.F90

@@ -387,11 +387,13 @@ module mgxs_header
 
       ! Get scattering treatment information
       ! Tabular_legendre tells us if we are to treat the provided
-      ! Legendre polynomials as tabular data (if enable is true) or leaving
-      ! them as Legendres (if enable is false, or the default)
+      ! Legendre polynomials as tabular data (if enable is true, default)
+      ! or leaving them as Legendres (if enable is false)
 
-      ! Set the default (leave as Legendre polynomials)
-      enable_leg_mu = .false.
+      ! Set the default (Convert to tabular format w/ 33 points)
+      enable_leg_mu = .true.
+      legendre_mu_points = 33
+      ! Get the user-provided values
       if (check_for_node(node_xsdata, "tabular_legendre")) then
         call get_node_ptr(node_xsdata, "tabular_legendre", node_legendre_mu)
         if (check_for_node(node_legendre_mu, "enable")) then

src/scattdata_header.F90

@@ -398,29 +398,18 @@ contains
           end do
 
           ! Re-normalize fmu for numerical integration issues and in case
-          ! the negative fix-up introduced un-normalized data
+          ! the negative fix-up introduced un-normalized data while
+          ! accruing the CDF
           norm = ZERO
           do imu = 2, order
             norm = norm + HALF * this % dmu * &
                  (this % fmu(gin) % data(imu - 1, gout) + &
                   this % fmu(gin) % data(imu, gout))
+            this % dist(gin) % data(imu, gout) = norm
           end do
           if (norm > ZERO) then
             this % fmu(gin) % data(:, gout) = &
                  this % fmu(gin) % data(:, gout) / norm
-          end if
-
-          ! Now create CDF from fmu with trapezoidal rule
-          this % dist(gin) % data(1, gout) = ZERO
-          do imu = 2, order
-            this % dist(gin) % data(imu, gout) = &
-                 this % dist(gin) % data(imu - 1, gout) + &
-                 HALF * this % dmu * (this % fmu(gin) % data(imu - 1, gout) + &
-                                      this % fmu(gin) % data(imu, gout))
-          end do
-          ! Ensure we normalize to 1 still
-          norm = this % dist(gin) % data(order, gout)
-          if (norm > ZERO) then
             this % dist(gin) % data(:, gout) = &
                  this % dist(gin) % data(:, gout) / norm
           end if
@@ -628,11 +617,10 @@ contains
     p1  = this % fmu(gin) % data(k + 1, gout)
     mu1 = this % mu(k + 1)
 
-    frac = (p1 - p0) / (mu1 - mu0)
-
-    if (frac == ZERO) then
+    if (p0 == p1) then
       mu = mu0 + (xi - c_k) / p0
     else
+      frac = (p1 - p0) / (mu1 - mu0)
       mu = mu0 + &
            (sqrt(max(ZERO, p0 * p0 + TWO * frac * (xi - c_k))) - p0) / frac
     end if

src/tally.F90

@@ -107,8 +107,6 @@ contains
     real(8) :: atom_density_        ! atom/b-cm
     real(8) :: f                    ! interpolation factor
     real(8) :: score                ! analog tally score
-    real(8) :: macro_total          ! material macro total xs
-    real(8) :: macro_scatt          ! material macro scatt xs
     real(8) :: E                    ! particle energy
 
     i = 0

tests/test_mg_basic/results_true.dat

@@ -1,2 +1,2 @@
 k-combined:
-1.033731E+00 4.974463E-02
+1.047136E+00 2.765964E-02

tests/test_mg_max_order/results_true.dat

@@ -1,2 +1,2 @@
 k-combined:
-1.055274E+00 1.715904E-02
+1.102093E+00 4.962190E-02

tests/test_mg_nuclide/results_true.dat

@@ -1,2 +1,2 @@
 k-combined:
-1.033731E+00 4.974463E-02
+1.047136E+00 2.765964E-02

tests/test_mgxs_library_ce_to_mg/results_true.dat

@@ -1,2 +1,2 @@
 k-combined:
-1.094839E+00 1.203524E-02
+1.140804E+00 2.937150E-02