Implementation of time distribution for the source

include/openmc/source.h

@@ -42,13 +42,13 @@ public:
 };
 
 //==============================================================================
-//! Source composed of independent spatial, angle, and energy distributions
+//! Source composed of independent spatial, angle, energy, and time distributions
 //==============================================================================
 
 class IndependentSource : public Source {
 public:
   // Constructors
-  IndependentSource(UPtrSpace space, UPtrAngle angle, UPtrDist energy);
+  IndependentSource(UPtrSpace space, UPtrAngle angle, UPtrDist energy, UPtrDist time);
   explicit IndependentSource(pugi::xml_node node);
 
   //! Sample from the external source distribution
@@ -64,6 +64,7 @@ public:
   SpatialDistribution* space() const { return space_.get(); }
   UnitSphereDistribution* angle() const { return angle_.get(); }
   Distribution* energy() const { return energy_.get(); }
+  Distribution* time() const { return time_.get(); }
 
 private:
   ParticleType particle_ {ParticleType::neutron}; //!< Type of particle emitted
@@ -71,6 +72,7 @@ private:
   UPtrSpace space_;                               //!< Spatial distribution
   UPtrAngle angle_;                               //!< Angular distribution
   UPtrDist energy_;                               //!< Energy distribution
+  UPtrDist time_;                                 //!< Time distribution
 };
 
 //==============================================================================

openmc/source.py

@@ -22,6 +22,8 @@ class Source:
         Angular distribution of source sites
     energy : openmc.stats.Univariate
         Energy distribution of source sites
+    time : openmc.stats.Univariate
+        time distribution of source sites
     filename : str
         Source file from which sites should be sampled
     library : str
@@ -43,6 +45,8 @@ class Source:
         Angular distribution of source sites
     energy : openmc.stats.Univariate or None
         Energy distribution of source sites
+    time : openmc.stats.Univariate or None
+        time distribution of source sites
     file : str or None
         Source file from which sites should be sampled
     library : str or None
@@ -56,11 +60,12 @@ class Source:
 
     """
 
-    def __init__(self, space=None, angle=None, energy=None, filename=None,
+    def __init__(self, space=None, angle=None, energy=None, time=None, filename=None,
                  library=None, parameters=None, strength=1.0, particle='neutron'):
         self._space = None
         self._angle = None
         self._energy = None
+        self._time = None
         self._file = None
         self._library = None
         self._parameters = None
@@ -71,6 +76,8 @@ class Source:
             self.angle = angle
         if energy is not None:
             self.energy = energy
+        if time is not None:
+            self.time = time
         if filename is not None:
             self.file = filename
         if library is not None:
@@ -104,6 +111,10 @@ class Source:
     def energy(self):
         return self._energy
 
+    @property
+    def time(self):
+        return self._time
+
     @property
     def strength(self):
         return self._strength
@@ -142,6 +153,11 @@ class Source:
         cv.check_type('energy distribution', energy, Univariate)
         self._energy = energy
 
+    @time.setter
+    def time(self, time):
+        cv.check_type('time distribution', time, Univariate)
+        self._time = time
+
     @strength.setter
     def strength(self, strength):
         cv.check_type('source strength', strength, Real)
@@ -178,6 +194,8 @@ class Source:
             element.append(self.angle.to_xml_element())
         if self.energy is not None:
             element.append(self.energy.to_xml_element('energy'))
+        if self.time is not None:
+            element.append(self.time.to_xml_element('time'))
         return element
 
     @classmethod
@@ -229,6 +247,11 @@ class Source:
         if energy is not None:
             source.energy = Univariate.from_xml_element(energy)
 
+        time = elem.find('time')
+        if time is not None:
+            source.time = Univariate.from_xml_element(time)
+
+
         return source
 
 

src/source.cpp

@@ -46,11 +46,12 @@ vector<unique_ptr<Source>> external_sources;
 // IndependentSource implementation
 //==============================================================================
 
-IndependentSource::IndependentSource(
-  UPtrSpace space, UPtrAngle angle, UPtrDist energy)
-  : space_ {std::move(space)}, angle_ {std::move(angle)}, energy_ {
-                                                            std::move(energy)}
-{}
+IndependentSource::IndependentSource(UPtrSpace space, UPtrAngle angle, UPtrDist energy, UPtrDist time)
+  : space_{std::move(space)},
+    angle_{std::move(angle)},
+    energy_{std::move(energy)},
+    time_{std::move(time)}
+{ }
 
 IndependentSource::IndependentSource(pugi::xml_node node)
 {
@@ -140,6 +141,17 @@ IndependentSource::IndependentSource(pugi::xml_node node)
       // Default to a Watt spectrum with parameters 0.988 MeV and 2.249 MeV^-1
       energy_ = UPtrDist {new Watt(0.988e6, 2.249e-6)};
     }
+
+    // Determine external source time distribution
+    if (check_for_node(node, "time")) {
+      pugi::xml_node node_dist = node.child("time");
+      time_ = distribution_from_xml(node_dist);
+    } else {
+      // Default to a Constant time T=0
+      double T[] {0.0};
+      double p[] {1.0};
+      time_ = UPtrDist {new Discrete{T, p, 1}};
+    }
   }
 }
 
@@ -224,6 +236,9 @@ SourceSite IndependentSource::sample(uint64_t* seed) const
       break;
   }
 
+  // Sample particle creation time
+  site.time = time_->sample(seed);
+  
   return site;
 }