diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index c39439ed39..5ad87d719c 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -74,11 +74,13 @@ class CylinderSector(CompositeSurface):
     r2 : float
         Outer radius of sector. Must be greater than r1.
     central_angle : float
-        Central angle, :math:`\\theta`, of the sector in degrees. Must be greater
-        that 0 and less than 360.
-    alpha : float
-        Angular offset, :math:`\\alpha`, of the clockwise-most side of the sector in degrees
-        relative to the first basis axis (+y, +z, or +x).
+        Central angle, :math:`\\theta`, of the sector in degrees. Must be
+        greater that 0 and less than 360.
+    ccw_offset : float
+        Angular offset, :math:`\\alpha`, in the counter-clockwise direction
+        with respect to the first basis axis (+y, +z, or +x) of the
+        clockwise-most side of the sector in degrees. Note that negative values
+        translate to a clockwise offset.
     axis : {'x', 'y', 'z'}
         Central axis of the cylinders defining the inner and outer surfaces
         of the sector. Defaults to 'z'.
@@ -101,7 +103,14 @@ class CylinderSector(CompositeSurface):
 
     _surface_names = ('outer_cyl', 'inner_cyl', 'plane1', 'plane2')
 
-    def __init__(self, center, r1, r2, central_angle, alpha, axis='z', **kwargs):
+    def __init__(self,
+                 center,
+                 r1,
+                 r2,
+                 central_angle,
+                 ccw_offset,
+                 axis='z',
+                 **kwargs):
 
         if r2 <= r1 * sqrt(2):
             raise ValueError(f'r2 must be greater than r1.')
@@ -109,8 +118,8 @@ class CylinderSector(CompositeSurface):
         if central_angle >= 360. or central_angle <= 0:
             raise ValueError(f'theta must be less than 360.')
 
-        phi1 = pi / 180 * alpha
-        phi2 = pi / 180 * (alpha + central_angle)
+        phi1 = pi / 180 * ccw_offset
+        phi2 = pi / 180 * (ccw_offset + central_angle)
 
         # Coords for axis-perpendicular planes
         p1 = np.array([0., 0., 1.])
diff --git a/tests/unit_tests/test_surface_composite.py b/tests/unit_tests/test_surface_composite.py
index 00e51e6d9a..458f11c60a 100644
--- a/tests/unit_tests/test_surface_composite.py
+++ b/tests/unit_tests/test_surface_composite.py
@@ -165,8 +165,8 @@ def test_cylinder_sector(axis, indices):
     r1, r2 = 0.5, 1.5
     d = (r2 - r1) / 2
     central_angle = 120.
-    alpha = -60.
-    s = openmc.model.CylinderSector(center, r1, r2, central_angle, alpha,
+    ccw_offset = -60.
+    s = openmc.model.CylinderSector(center, r1, r2, central_angle, ccw_offset,
                                     axis=axis.lower())
     assert isinstance(s.outer_cyl, getattr(openmc, axis + "Cylinder"))
     assert isinstance(s.inner_cyl, getattr(openmc, axis + "Cylinder"))
@@ -206,13 +206,13 @@ def test_cylinder_sector(axis, indices):
 
     # Check invalid r1, r2 combinations
     with pytest.raises(ValueError):
-        openmc.model.CylinderSector(center, 10., 1., central_angle, alpha)
+        openmc.model.CylinderSector(center, 10., 1., central_angle, ccw_offset)
 
     # Check invalid sector width
     with pytest.raises(ValueError):
-        openmc.model.CylinderSector(center, 1., 10., 360, alpha)
+        openmc.model.CylinderSector(center, 1., 10., 360, ccw_offset)
     with pytest.raises(ValueError):
-        openmc.model.CylinderSector(center, 1., 10., -1, alpha)
+        openmc.model.CylinderSector(center, 1., 10., -1, ccw_offset)
 
     # Make sure repr works
     repr(s)