diff --git a/src/ace.F90 b/src/ace.F90
index c9a19d257a..87ee49f1c8 100644
--- a/src/ace.F90
+++ b/src/ace.F90
@@ -1123,8 +1123,7 @@ contains
 !===============================================================================
 ! READ_THERMAL_DATA reads elastic and inelastic cross sections and corresponding
 ! secondary energy/angle distributions derived from experimental S(a,b)
-! data. Namely, in MCNP language, this routine reads the ITIE, ITCE, ITXE, and
-! ITCA blocks.
+! data. Namely, this routine reads the ITIE, ITCE, ITXE, and ITCA blocks.
 !===============================================================================
 
   subroutine read_thermal_data(table)
diff --git a/src/cmfd_data.F90 b/src/cmfd_data.F90
index c966070cd9..e6e3665feb 100644
--- a/src/cmfd_data.F90
+++ b/src/cmfd_data.F90
@@ -1,7 +1,7 @@
 module cmfd_data
 
 !==============================================================================
-! CMFD_DATA -- This module processes the MC21 cmfd tally object to generate
+! CMFD_DATA -- This module processes the cmfd tally object to generate
 ! parameters for CMFD calculation.
 !==============================================================================
 
diff --git a/src/cmfd_execute.F90 b/src/cmfd_execute.F90
index e0069b1e45..c6b04354b5 100644
--- a/src/cmfd_execute.F90
+++ b/src/cmfd_execute.F90
@@ -2,7 +2,7 @@ module cmfd_execute
 
 !==============================================================================
 ! CMFD_EXECUTE -- This module is the highest level cmfd module that controls the
-! cross section generation, diffusion calculation, and MC21 source re-weighting
+! cross section generation, diffusion calculation, and source re-weighting
 !==============================================================================
 
   implicit none
diff --git a/src/constants.F90 b/src/constants.F90
index 5b605f291d..6ebab532b3 100644
--- a/src/constants.F90
+++ b/src/constants.F90
@@ -337,9 +337,9 @@ module constants
 
   ! Energy grid methods
   integer, parameter :: &
-       GRID_NUCLIDE  = 1, & ! non-unionized energy grid (MCNP)
+       GRID_NUCLIDE  = 1, & ! non-unionized energy grid
        GRID_UNION    = 2, & ! union grid with pointers
-       GRID_LETHARGY = 3    ! lethargy mapping (MC21)
+       GRID_LETHARGY = 3    ! lethargy mapping
 
   ! Running modes
   integer, parameter ::        &
diff --git a/src/physics.F90 b/src/physics.F90
index 12dccef40d..783bc1178b 100644
--- a/src/physics.F90
+++ b/src/physics.F90
@@ -1525,8 +1525,7 @@ contains
           end if
 
        elseif (INTT == LINEAR_LINEAR) then
-          ! Linear-linear interpolation -- not sure how you come about the
-          ! formula given in the MCNP manual
+          ! Linear-linear interpolation
           E_l_k1 = edist % data(lc+k+1)
           p_l_k1 = edist % data(lc+NP+k+1)
 
@@ -1763,8 +1762,7 @@ contains
           KM_A = edist % data(lc + 4*NP + k)
 
        elseif (INTT == LINEAR_LINEAR) then
-          ! Linear-linear interpolation -- not sure how you come about the
-          ! formula given in the MCNP manual
+          ! Linear-linear interpolation
           E_l_k1 = edist % data(lc+k+1)
           p_l_k1 = edist % data(lc+NP+k+1)
 
@@ -1909,8 +1907,7 @@ contains
           end if
 
        elseif (INTT == LINEAR_LINEAR) then
-          ! Linear-linear interpolation -- not sure how you come about the
-          ! formula given in the MCNP manual
+          ! Linear-linear interpolation
           E_l_k1 = edist % data(lc+k+1)
           p_l_k1 = edist % data(lc+NP+k+1)
 
@@ -1975,8 +1972,7 @@ contains
           end if
 
        elseif (JJ == LINEAR_LINEAR) then
-          ! Linear-linear interpolation -- not sure how you come about the
-          ! formula given in the MCNP manual
+          ! Linear-linear interpolation
           p_k1  = edist % data(lc + NP + k+1)
           mu_k1 = edist % data(lc + k+1)