@@ -412,6 +412,7 @@ list(APPEND libopenmc_SOURCES
   src/tallies/filter_particle.cpp
   src/tallies/filter_particle_production.cpp
   src/tallies/filter_polar.cpp
+  src/tallies/filter_reaction.cpp
   src/tallies/filter_sph_harm.cpp
   src/tallies/filter_sptl_legendre.cpp
   src/tallies/filter_surface.cpp
 
@@ -149,6 +149,7 @@ Constructing Tallies
    openmc.ZernikeRadialFilter
    openmc.ParentNuclideFilter
    openmc.ParticleFilter
+   openmc.ReactionFilter
    openmc.MeshMaterialVolumes
    openmc.Trigger
    openmc.TallyDerivative
 
@@ -82,7 +82,9 @@ Classes
    Nuclide
    ParentNuclideFilter
    ParticleFilter
+   ParticleProductionFilter
    PolarFilter
+   ReactionFilter
    RectilinearMesh
    RegularMesh
    SpatialLegendreFilter
 
@@ -227,6 +227,7 @@ enum ReactionType {
   N_XA = 207,
   HEATING = 301,
   DAMAGE_ENERGY = 444,
+  PHOTON_TOTAL = 501,
   COHERENT = 502,
   INCOHERENT = 504,
   PAIR_PROD_ELEC = 515,
 
@@ -33,6 +33,13 @@ bool is_disappearance(int MT);
 //! \return Whether corresponding reaction is an inelastic scattering reaction
 bool is_inelastic_scatter(int MT);
 
+//! Determine whether an MT number matches a target MT, considering that the
+//! target may be a summation reaction.
+//! \param[in] event_mt MT number of the actual event
+//! \param[in] target_mt MT number to check against
+//! \return Whether event_mt is a component of target_mt (or equal to it)
+bool mt_matches(int event_mt, int target_mt);
+
 //==============================================================================
 //! Abstract one-dimensional function
 //==============================================================================
 
@@ -76,11 +76,21 @@ class Reaction {
 //! \return Name of the corresponding reaction
 std::string reaction_name(int mt);
 
-//! Return reaction type (MT value) given a reaction name
+//! Return MT value for given a reaction name (including special tally MT
+//! values)
 //
 //! \param[in] name  Reaction name
-//! \return Corresponding reaction type (MT value)
-int reaction_type(std::string name);
+//! \return Corresponding MT number or special tally score
+int reaction_tally_mt(std::string name);
+
+//! Return ENDF MT number given a reaction name
+//
+//! Unlike reaction_tally_mt(), this function always returns a positive ENDF MT
+//! number and never a special negative tally score.
+//!
+//! \param[in] name  Reaction name
+//! \return Corresponding ENDF MT number
+int reaction_mt(const std::string& name);
 
 } // namespace openmc
 
 
@@ -41,6 +41,7 @@ enum class FilterType {
   PARTICLE,
   PARTICLE_PRODUCTION,
   POLAR,
+  REACTION,
   SPHERICAL_HARMONICS,
   SPATIAL_LEGENDRE,
   SURFACE,
 
@@ -0,0 +1,52 @@
+#ifndef OPENMC_TALLIES_FILTER_REACTION_H
+#define OPENMC_TALLIES_FILTER_REACTION_H
+
+#include "openmc/span.h"
+#include "openmc/tallies/filter.h"
+#include "openmc/vector.h"
+
+namespace openmc {
+
+//==============================================================================
+//! Bins tally events based on the reaction type (MT number).
+//==============================================================================
+
+class ReactionFilter : public Filter {
+public:
+  //----------------------------------------------------------------------------
+  // Constructors, destructors
+
+  ~ReactionFilter() = default;
+
+  //----------------------------------------------------------------------------
+  // Methods
+
+  std::string type_str() const override { return "reaction"; }
+  FilterType type() const override { return FilterType::REACTION; }
+
+  void from_xml(pugi::xml_node node) override;
+
+  void get_all_bins(const Particle& p, TallyEstimator estimator,
+    FilterMatch& match) const override;
+
+  void to_statepoint(hid_t filter_group) const override;
+
+  std::string text_label(int bin) const override;
+
+  //----------------------------------------------------------------------------
+  // Accessors
+
+  const vector<int>& bins() const { return bins_; }
+  void set_bins(span<const int> bins);
+
+protected:
+  //----------------------------------------------------------------------------
+  // Data members
+
+  //! MT numbers to match
+  vector<int> bins_;
+};
+
+} // namespace openmc
+
+#endif // OPENMC_TALLIES_FILTER_REACTION_H
@@ -21,6 +21,7 @@
 from .kalbach_mann import KalbachMann
 from .laboratory import LaboratoryAngleEnergy
 from .nbody import NBodyPhaseSpace
+from .photon import _SUBSHELLS
 from .product import Product
 from .uncorrelated import UncorrelatedAngleEnergy
 
@@ -54,6 +55,10 @@
                  198: '(n,n3p)', 199: '(n,3n2pa)', 200: '(n,5n2p)', 203: '(n,Xp)',
                  204: '(n,Xd)', 205: '(n,Xt)', 206: '(n,X3He)', 207: '(n,Xa)',
                  301: 'heating', 444: 'damage-energy',
+                 501: 'photon-total', 502: 'coherent-scatter',
+                 504: 'incoherent-scatter', 515: 'pair-production-electron',
+                 516: 'pair-production', 517: 'pair-production-nuclear',
+                 522: 'photoelectric',
                  649: '(n,pc)', 699: '(n,dc)', 749: '(n,tc)', 799: '(n,3Hec)',
                  849: '(n,ac)', 891: '(n,2nc)', 901: 'heating-local'}
 REACTION_NAME.update({i: f'(n,n{i - 50})' for i in range(51, 91)})
@@ -63,9 +68,16 @@
 REACTION_NAME.update({i: f'(n,3He{i - 750})' for i in range(750, 799)})
 REACTION_NAME.update({i: f'(n,a{i - 800})' for i in range(800, 849)})
 REACTION_NAME.update({i: f'(n,2n{i - 875})' for i in range(875, 891)})
+REACTION_NAME.update(
+    {534 + i: f'photoelectric-{shell}' for i, shell in enumerate(_SUBSHELLS[1:])}
+)
 
 REACTION_MT = {name: mt for mt, name in REACTION_NAME.items()}
+REACTION_MT['total'] = 1
+REACTION_MT['elastic'] = 2
 REACTION_MT['fission'] = 18
+REACTION_MT['absorption'] = 27
+REACTION_MT['capture'] = 102
 
 FISSION_MTS = (18, 19, 20, 21, 38)