From 9350e99061bf8bd08935fef5c88d44272e3e997f Mon Sep 17 00:00:00 2001
From: yardasol <yardasol@grinnell.edu>
Date: Fri, 1 Apr 2022 15:54:29 -0500
Subject: [PATCH 01/24] added CylinderSector composite surface

---
 openmc/model/surface_composite.py | 89 +++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 09a3c0170..0151d19e8 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -165,6 +165,95 @@ class RectangularParallelepiped(CompositeSurface):
     def __pos__(self):
         return -self.xmin | +self.xmax | -self.ymin | +self.ymax | -self.zmin | +self.zmax
 
+class CylinderSector(CompositeSurface):
+    """Infinite cylindrical sector composite surface
+
+    This class
+    acts as a proper surface, meaning that unary `+` and `-` operators applied
+    to it will produce a half-space. The negative side is defined to be the
+    region inside of the octogonal prism.
+
+    Parameters
+    ----------
+    center_axis : 2-tuple
+         (x,y), (x,z), or (y,z) coordiante of cylinders' central axes.
+         Defaults to (0,0)
+    r1, r2 : float
+        Inner and outer cylinder radii
+    alpha1, alpha2 : float
+        Angular segmentation in degrees relative to the x-, x-, or y-axis.
+    axis : {'z', 'y', 'x'}
+        Axes of the cylinders
+    **kwargs
+        Keyword arguments passed to underlying plane classes
+
+    Attributes
+    ----------
+    outer : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
+        Outer cylinder surface
+    inner : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
+        Inner cylinder surface
+    plane_1 : openmc.Plane
+        Segment plane corresponding to :attr:`alpha1`
+    plane_2 : openmc.Plane
+        Segmenting plane correspodning to :attr:`alpha2`
+
+    """
+
+    _surface_names = ('outer','inner',
+                      'plane_a', 'plane_b')
+
+    def __init__(self, center, r1, r2, alpha1, alpha2, **kwargs):
+
+        alpha1 = np.pi / 180 * alpha1
+        alpha2 = np.pi / 180 * alpha2
+        # Coords for axis-perpendicular planes
+        p1 = np.array([0,0,1])
+
+        p2_plane1 = np.array([r1 * np.cos(alpha1), -r1 * np.sin(alpha1), 0])
+        p3_plane1 = np.array([r2 * np.cos(alpha1), -r2 * np.sin(alpha1), 0])
+
+        p2_plane2 = np.array([r1 * np.cos(alpha2), r1 * np.sin(alpha2), 0])
+        p3_plane2 = np.array([r2 * np.cos(alpha2), r2 * np.sin(alpha2), 0])
+
+        points = [p1, p2_plane1, p3_plane1, p2_plane2, p3_plane2]
+        if axis == 'x':
+            self.inner = openmc.XCylinder(*center_axis, r=r1, **kwargs)
+            self.outer = openmc.XCylinder(*center_axis, r=r2, **kwargs)
+            coord_map = [2,0,1]
+         elif axis == 'y':
+            self.inner = openmc.YCylinder(*center_axis, r=r1, **kwargs)
+            self.outer = openmc.YCylinder(*center_axis, r=r2, **kwargs)
+            coord_map = [0,2,1]
+         elif axis == 'z':
+            self.inner = openmc.ZCylinder(*center_axis, r=r1, **kwargs)
+            self.outer = openmc.ZCylinder(*center_axis, r=r2, **kwargs)
+            coord_map = [0,1,2]
+
+        calibrated_points = []
+        for p in points:
+            p_temp = []
+            for i in coord_map:
+                p_temp += [p[i]]
+            calibrated_points += [np.array(p_temp)]
+
+        p1, p2_plane1, p3_plane1, p2_plane2, p3_plane2 = calibrated_points
+
+        plane1_params = _plane_from_points(p1, p2_plane1, p3_plane1)
+        plane2_params = _plane_from_points(p1, p2_plane2, p3_plane2)
+
+        self.inner = openmc.ZCylinder(x0=x0, y0=y0, r=r1, **kwargs)
+        self.outer = openmc.ZCylinder(x0=x0, y0=y0, r=r2, **kwargs)
+        self.plane1 = openmc.Plane(*plane1_params, **kwargs)
+        self.plane2 = openmc.Plane(*plane2_params, **kwargs)
+
+
+    def __neg__(self):
+        return -self.outer & +self.inner & -self.plane1 &  +self.plane2
+
+
+    def __pos__(self):
+        return +self.outer | -self.inner | +self.plane1 | -self.plane2
 
 class XConeOneSided(CompositeSurface):
     """One-sided cone parallel the x-axis

From 1cc80135f3158a8c9c51199ab282a546c554bc20 Mon Sep 17 00:00:00 2001
From: yardasol <yardasol@grinnell.edu>
Date: Mon, 4 Apr 2022 16:21:42 -0500
Subject: [PATCH 02/24] consitency changes to CylinderSector

---
 openmc/model/surface_composite.py | 89 ++++++++++++++++---------------
 1 file changed, 46 insertions(+), 43 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 0151d19e8..9b674b494 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -2,6 +2,7 @@ from abc import ABC, abstractmethod
 from copy import copy
 
 import openmc
+from math import sin, cos, sqrt
 from openmc.checkvalue import check_greater_than, check_value
 
 
@@ -168,22 +169,24 @@ class RectangularParallelepiped(CompositeSurface):
 class CylinderSector(CompositeSurface):
     """Infinite cylindrical sector composite surface
 
-    This class
-    acts as a proper surface, meaning that unary `+` and `-` operators applied
-    to it will produce a half-space. The negative side is defined to be the
-    region inside of the octogonal prism.
+    This class acts as a proper surface, meaning that unary `+` and `-`
+    operators applied to it will produce a half-space. The negative
+    side is defined to be the region inside of the cylinder sector.
 
     Parameters
     ----------
-    center_axis : 2-tuple
-         (x,y), (x,z), or (y,z) coordiante of cylinders' central axes.
-         Defaults to (0,0)
+    center : iterable of float
+         Coordinate for central axes of cylinders in the (y, z), (x,z), or
+         (x, y) basis. Defaults to (0,0)
     r1, r2 : float
         Inner and outer cylinder radii
-    alpha1, alpha2 : float
-        Angular segmentation in degrees relative to the x-, x-, or y-axis.
+    theta0 : float
+        Angular offset of the sector in degrees relative to the primary basis
+        axis (+y or +x).
+    theta : float
+        Angular width of the sector in degrees.
     axis : {'z', 'y', 'x'}
-        Axes of the cylinders
+        Central axis of the cylinders. Defaults to z
     **kwargs
         Keyword arguments passed to underlying plane classes
 
@@ -193,67 +196,67 @@ class CylinderSector(CompositeSurface):
         Outer cylinder surface
     inner : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
         Inner cylinder surface
-    plane_1 : openmc.Plane
-        Segment plane corresponding to :attr:`alpha1`
-    plane_2 : openmc.Plane
-        Segmenting plane correspodning to :attr:`alpha2`
+    plane0 : openmc.Plane
+        Plane at angle :math:`\theta_0` relative to the first basis axis
+    plane1 : openmc.Plane
+        Plane at angle :math:`\theta_0 + \theta` relative to the first
+        basis axis.
 
     """
 
     _surface_names = ('outer','inner',
-                      'plane_a', 'plane_b')
+                      'plane0', 'plane1')
 
-    def __init__(self, center, r1, r2, alpha1, alpha2, **kwargs):
+    def __init__(self, center, r1, r2, theta0, theta, axis='z', **kwargs):
+
+        theta0 = np.pi / 180 * theta0
+        theta = np.pi / 180 * theta
+        theta1 = theta0 + theta
 
-        alpha1 = np.pi / 180 * alpha1
-        alpha2 = np.pi / 180 * alpha2
         # Coords for axis-perpendicular planes
-        p1 = np.array([0,0,1])
+        p1 = np.array([0,0])
 
-        p2_plane1 = np.array([r1 * np.cos(alpha1), -r1 * np.sin(alpha1), 0])
-        p3_plane1 = np.array([r2 * np.cos(alpha1), -r2 * np.sin(alpha1), 0])
+        p2_plane0 = np.array([r1 * cos(theta0), r1 * sin(theta0)])
+        p3_plane0 = np.array([r2 * cos(theta0), r2 * sin(theta0)])
 
-        p2_plane2 = np.array([r1 * np.cos(alpha2), r1 * np.sin(alpha2), 0])
-        p3_plane2 = np.array([r2 * np.cos(alpha2), r2 * np.sin(alpha2), 0])
+        p2_plane1 = np.array([r1 * cos(theta1), r1 * sin(theta1)])
+        p3_plane1 = np.array([r2 * cos(theta1), r2 * sin(theta1)])
 
-        points = [p1, p2_plane1, p3_plane1, p2_plane2, p3_plane2]
+        points = [p2_plane0, p3_plane0, p2_plane1, p3_plane1]
         if axis == 'x':
-            self.inner = openmc.XCylinder(*center_axis, r=r1, **kwargs)
-            self.outer = openmc.XCylinder(*center_axis, r=r2, **kwargs)
-            coord_map = [2,0,1]
+            self.inner = openmc.XCylinder(*center, r=r1, **kwargs)
+            self.outer = openmc.XCylinder(*center, r=r2, **kwargs)
+            axis_idx = 0
          elif axis == 'y':
-            self.inner = openmc.YCylinder(*center_axis, r=r1, **kwargs)
-            self.outer = openmc.YCylinder(*center_axis, r=r2, **kwargs)
-            coord_map = [0,2,1]
+            self.inner = openmc.YCylinder(*center, r=r1, **kwargs)
+            self.outer = openmc.YCylinder(*center, r=r2, **kwargs)
+            axis_idx = 1
          elif axis == 'z':
-            self.inner = openmc.ZCylinder(*center_axis, r=r1, **kwargs)
-            self.outer = openmc.ZCylinder(*center_axis, r=r2, **kwargs)
-            coord_map = [0,1,2]
+            self.inner = openmc.ZCylinder(*center, r=r1, **kwargs)
+            self.outer = openmc.ZCylinder(*center, r=r2, **kwargs)
+            axis_idx = 3
 
         calibrated_points = []
         for p in points:
             p_temp = []
             for i in coord_map:
-                p_temp += [p[i]]
-            calibrated_points += [np.array(p_temp)]
+            calibrated_points += [np.insert(p, axis_idx, 0)]
 
-        p1, p2_plane1, p3_plane1, p2_plane2, p3_plane2 = calibrated_points
-
-        plane1_params = _plane_from_points(p1, p2_plane1, p3_plane1)
-        plane2_params = _plane_from_points(p1, p2_plane2, p3_plane2)
+        p2_plane0, p3_plane0, p2_plane1, p3_plane1 = calibrated_points
+        p1 = np.insert(p1, axis_idx, 1)
 
+        self.plane0 = openmc.Plane.from_points(p1, p2_plane0, p3_plane0, **kwargs)
+        self.plane1 = openmc.Plane.from_points(p1, p2_plane1, p3_plane1, **kwargs)
         self.inner = openmc.ZCylinder(x0=x0, y0=y0, r=r1, **kwargs)
         self.outer = openmc.ZCylinder(x0=x0, y0=y0, r=r2, **kwargs)
-        self.plane1 = openmc.Plane(*plane1_params, **kwargs)
-        self.plane2 = openmc.Plane(*plane2_params, **kwargs)
 
 
     def __neg__(self):
-        return -self.outer & +self.inner & -self.plane1 &  +self.plane2
+        return -self.outer & +self.inner & -self.plane0 &  +self.plane1
 
 
     def __pos__(self):
-        return +self.outer | -self.inner | +self.plane1 | -self.plane2
+        return +self.outer | -self.inner | +self.plane0 | -self.plane1
 
 class XConeOneSided(CompositeSurface):
     """One-sided cone parallel the x-axis

From e10e2bbcf02165db2a5f324f6a41761f56633724 Mon Sep 17 00:00:00 2001
From: yardasol <yardasol@grinnell.edu>
Date: Mon, 4 Apr 2022 16:47:06 -0500
Subject: [PATCH 03/24] streamline the remapping of coordinates

---
 openmc/model/surface_composite.py | 47 +++++++++++++++----------------
 1 file changed, 23 insertions(+), 24 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 9b674b494..2b55615a1 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -1,8 +1,9 @@
 from abc import ABC, abstractmethod
 from copy import copy
+from math import sqrt, pi, sin, cos
+from numpy import array
 
 import openmc
-from math import sin, cos, sqrt
 from openmc.checkvalue import check_greater_than, check_value
 
 
@@ -209,41 +210,39 @@ class CylinderSector(CompositeSurface):
 
     def __init__(self, center, r1, r2, theta0, theta, axis='z', **kwargs):
 
-        theta0 = np.pi / 180 * theta0
-        theta = np.pi / 180 * theta
+        theta0 = pi / 180 * theta0
+        theta = pi / 180 * theta
         theta1 = theta0 + theta
 
         # Coords for axis-perpendicular planes
-        p1 = np.array([0,0])
+        p1 = array([0.,0.,1.])
 
-        p2_plane0 = np.array([r1 * cos(theta0), r1 * sin(theta0)])
-        p3_plane0 = np.array([r2 * cos(theta0), r2 * sin(theta0)])
+        p2_plane0 = array([r1 * cos(theta0), r1 * sin(theta0), 0.])
+        p3_plane0 = array([r2 * cos(theta0), r2 * sin(theta0), 0.])
 
-        p2_plane1 = np.array([r1 * cos(theta1), r1 * sin(theta1)])
-        p3_plane1 = np.array([r2 * cos(theta1), r2 * sin(theta1)])
+        p2_plane1 = array([r1 * cos(theta1), r1 * sin(theta1), 0.])
+        p3_plane1 = array([r2 * cos(theta1), r2 * sin(theta1), 0.])
 
-        points = [p2_plane0, p3_plane0, p2_plane1, p3_plane1]
-        if axis == 'x':
-            self.inner = openmc.XCylinder(*center, r=r1, **kwargs)
-            self.outer = openmc.XCylinder(*center, r=r2, **kwargs)
-            axis_idx = 0
-         elif axis == 'y':
-            self.inner = openmc.YCylinder(*center, r=r1, **kwargs)
-            self.outer = openmc.YCylinder(*center, r=r2, **kwargs)
-            axis_idx = 1
-         elif axis == 'z':
+        points = [p1, p2_plane0, p3_plane0, p2_plane1, p3_plane1]
+        if axis == 'z':
+            coord_map = [0,1,2]
             self.inner = openmc.ZCylinder(*center, r=r1, **kwargs)
             self.outer = openmc.ZCylinder(*center, r=r2, **kwargs)
-            axis_idx = 3
+
+        elif axis == 'y':
+             coord_map = [0,2,1]
+            self.inner = openmc.YCylinder(*center, r=r1, **kwargs)
+            self.outer = openmc.YCylinder(*center, r=r2, **kwargs)
+        elif axis == 'x':
+            coord_map = [2,0,1]
+            self.inner = openmc.XCylinder(*center, r=r1, **kwargs)
+            self.outer = openmc.XCylinder(*center, r=r2, **kwargs)
 
         calibrated_points = []
         for p in points:
-            p_temp = []
-            for i in coord_map:
-            calibrated_points += [np.insert(p, axis_idx, 0)]
+            calibrated_points += [p[coord_map]]
 
-        p2_plane0, p3_plane0, p2_plane1, p3_plane1 = calibrated_points
-        p1 = np.insert(p1, axis_idx, 1)
+        p1, p2_plane0, p3_plane0, p2_plane1, p3_plane1 = calibrated_points
 
         self.plane0 = openmc.Plane.from_points(p1, p2_plane0, p3_plane0, **kwargs)
         self.plane1 = openmc.Plane.from_points(p1, p2_plane1, p3_plane1, **kwargs)

From 41460568a6a743051f90b8fc7b907e74303ca1e0 Mon Sep 17 00:00:00 2001
From: yardasol <yardasol@grinnell.edu>
Date: Mon, 4 Apr 2022 17:13:39 -0500
Subject: [PATCH 04/24] minor syntax fix

---
 openmc/model/surface_composite.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 2b55615a1..1635e21b6 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -257,6 +257,7 @@ class CylinderSector(CompositeSurface):
     def __pos__(self):
         return +self.outer | -self.inner | +self.plane0 | -self.plane1
 
+
 class XConeOneSided(CompositeSurface):
     """One-sided cone parallel the x-axis
 

From ae881a126d8239d64ff8b31a67342e121005dafa Mon Sep 17 00:00:00 2001
From: yardasol <yardasol@grinnell.edu>
Date: Mon, 4 Apr 2022 18:05:40 -0500
Subject: [PATCH 05/24] Added unit test

---
 tests/unit_tests/test_surface_composite.py | 56 ++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/tests/unit_tests/test_surface_composite.py b/tests/unit_tests/test_surface_composite.py
index a1a218311..bafff706e 100644
--- a/tests/unit_tests/test_surface_composite.py
+++ b/tests/unit_tests/test_surface_composite.py
@@ -150,3 +150,59 @@ def test_cone_one_sided(axis, point_pos, point_neg, ll_true):
 
     # Make sure repr works
     repr(s)
+
+@pytest.mark.parametrize(
+    "axis, indices", [
+        ("X", [0, 1, 2]),
+        ("Y", [1, 2, 0]),
+        ("Z", [2, 0, 1]),
+    ]
+)
+def test_cylinder_sector(axis, indices):
+    center = [0., 0.]
+    r1, r2 = 0.5, 1.5
+    d = (r2 - r1) / 2
+    theta0 = -60.
+    theta = 120.
+    s = openmc.model.CylinderSector(center, r1, r2, theta0, theta,
+                                    axis=axis.lower())
+    assert isinstance(s.outer_cyl, getattr(openmc, axis + "Cylinder"))
+    assert isinstance(s.inner_cyl, getattr(openmc, axis + "Cylinder"))
+    assert isinstance(s.plane0, openmc.Plane)
+    assert isinstance(s.plane1, openmc.Plane)
+
+    # Make sure boundary condition propagates
+    s.boundary_type = 'reflective'
+    assert s.boundary_type == 'reflective'
+    assert s.outer_cyl.boundary_type == 'reflective'
+    assert s.inner_cyl.boundary_type == 'reflective'
+    assert s.plane0.boundary_type == 'reflective'
+    assert s.plane1.boundary_type == 'reflective'
+
+    # Check bounding box
+    ll, ur = (+s).bounding_box
+    assert np.all(np.isinf(ll))
+    assert np.all(np.isinf(ur))
+    ll, ur = (-s).bounding_box
+    assert ll == pytest.approx(np.roll([-np.inf, -r2, -r2], indices[0]))
+    assert ur == pytest.approx(np.roll([np.inf, r2, r2], indices[0]))
+
+    # __contains__ on associated half-spaces
+    point_pos = np.roll([0, r2 + 1, 0], indices[0])
+    assert point_pos in +s
+    assert point_pos not in -s
+    point_neg = np.roll([0, r1 + d/2, r1 + d/2], indices[0])
+    assert point_neg in -s
+    assert point_neg not in +s
+
+    # translate method
+    t = uniform(-5.0, 5.0)
+    s_t = s.translate((t, t, t))
+    ll_t, ur_t = (-s_t).bounding_box
+    assert ur_t == pytest.approx(ur + t)
+    assert ll_t == pytest.approx(ll + t)
+
+    # Make sure repr works
+    repr(s)
+
+

From 10123bf55a9c74df880f261460381af4092f975c Mon Sep 17 00:00:00 2001
From: yardasol <yardasol@grinnell.edu>
Date: Mon, 4 Apr 2022 18:05:54 -0500
Subject: [PATCH 06/24] consistency changes

---
 openmc/model/surface_composite.py | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 1635e21b6..a7c8d173e 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -205,11 +205,12 @@ class CylinderSector(CompositeSurface):
 
     """
 
-    _surface_names = ('outer','inner',
+    _surface_names = ('outer_cyl','inner_cyl',
                       'plane0', 'plane1')
 
     def __init__(self, center, r1, r2, theta0, theta, axis='z', **kwargs):
 
+        self._axis = axis
         theta0 = pi / 180 * theta0
         theta = pi / 180 * theta
         theta1 = theta0 + theta
@@ -226,17 +227,16 @@ class CylinderSector(CompositeSurface):
         points = [p1, p2_plane0, p3_plane0, p2_plane1, p3_plane1]
         if axis == 'z':
             coord_map = [0,1,2]
-            self.inner = openmc.ZCylinder(*center, r=r1, **kwargs)
-            self.outer = openmc.ZCylinder(*center, r=r2, **kwargs)
-
+            self.inner_cyl = openmc.ZCylinder(*center, r=r1, **kwargs)
+            self.outer_cyl = openmc.ZCylinder(*center, r=r2, **kwargs)
         elif axis == 'y':
-             coord_map = [0,2,1]
-            self.inner = openmc.YCylinder(*center, r=r1, **kwargs)
-            self.outer = openmc.YCylinder(*center, r=r2, **kwargs)
+            coord_map = [0,2,1]
+            self.inner_cyl = openmc.YCylinder(*center, r=r1, **kwargs)
+            self.outer_cyl = openmc.YCylinder(*center, r=r2, **kwargs)
         elif axis == 'x':
             coord_map = [2,0,1]
-            self.inner = openmc.XCylinder(*center, r=r1, **kwargs)
-            self.outer = openmc.XCylinder(*center, r=r2, **kwargs)
+            self.inner_cyl = openmc.XCylinder(*center, r=r1, **kwargs)
+            self.outer_cyl = openmc.XCylinder(*center, r=r2, **kwargs)
 
         calibrated_points = []
         for p in points:
@@ -246,16 +246,20 @@ class CylinderSector(CompositeSurface):
 
         self.plane0 = openmc.Plane.from_points(p1, p2_plane0, p3_plane0, **kwargs)
         self.plane1 = openmc.Plane.from_points(p1, p2_plane1, p3_plane1, **kwargs)
-        self.inner = openmc.ZCylinder(x0=x0, y0=y0, r=r1, **kwargs)
-        self.outer = openmc.ZCylinder(x0=x0, y0=y0, r=r2, **kwargs)
 
 
     def __neg__(self):
-        return -self.outer & +self.inner & -self.plane0 &  +self.plane1
+        if self._axis == 'y':
+            return -self.outer_cyl & +self.inner_cyl & +self.plane0 &  -self.plane1
+        else:
+            return -self.outer_cyl & +self.inner_cyl & -self.plane0 &  +self.plane1
 
 
     def __pos__(self):
-        return +self.outer | -self.inner | +self.plane0 | -self.plane1
+        if self._axis == 'y':
+            return +self.outer_cyl | -self.inner_cyl | -self.plane0 | +self.plane1
+        else:
+            return +self.outer_cyl | -self.inner_cyl | +self.plane0 | -self.plane1
 
 
 class XConeOneSided(CompositeSurface):

From 370625be5532050f8c8ac0f581b9e35f0575ab03 Mon Sep 17 00:00:00 2001
From: yardasol <yardasol@grinnell.edu>
Date: Mon, 4 Apr 2022 18:06:48 -0500
Subject: [PATCH 07/24] Added reference to CylinderSector in the sphinx
 documentation

---
 docs/source/pythonapi/model.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/docs/source/pythonapi/model.rst b/docs/source/pythonapi/model.rst
index a6c89be7c..686bc8d1c 100644
--- a/docs/source/pythonapi/model.rst
+++ b/docs/source/pythonapi/model.rst
@@ -25,6 +25,7 @@ Composite Surfaces
    :nosignatures:
    :template: myclass.rst
 
+   openmc.model.CylinderSector
    openmc.model.RectangularParallelepiped
    openmc.model.RightCircularCylinder
    openmc.model.XConeOneSided

From be6afdc3355bfa26ca3c093f3cab01842a14e7ea Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Tue, 5 Apr 2022 10:31:31 -0500
Subject: [PATCH 08/24] optimize implementation

---
 openmc/model/surface_composite.py | 178 ++++++++++++++----------------
 1 file changed, 84 insertions(+), 94 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index a7c8d173e..03595ff4b 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -53,6 +53,90 @@ class CompositeSurface(ABC):
         """Return the negative half-space of the composite surface."""
 
 
+class CylinderSector(CompositeSurface):
+    """Infinite cylindrical sector composite surface
+
+    This class acts as a proper surface, meaning that unary `+` and `-`
+    operators applied to it will produce a half-space. The negative
+    side is defined to be the region inside of the cylinder sector.
+
+    Parameters
+    ----------
+    center : iterable of float
+         Coordinate for central axes of cylinders in the (y, z), (z, x), or
+         (x, y) basis. Defaults to (0,0)
+    r1, r2 : float
+        Inner and outer cylinder radii
+    theta0 : float
+        Angular offset of the sector in degrees relative to the primary basis
+        axis (+y, +z, or +x).
+    theta : float
+        Angular width of the sector in degrees.
+    axis : {'z', 'y', 'x'}
+        Central axis of the cylinders. Defaults to z
+    **kwargs
+        Keyword arguments passed to underlying plane classes
+
+    Attributes
+    ----------
+    outer : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
+        Outer cylinder surface
+    inner : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
+        Inner cylinder surface
+    plane0 : openmc.Plane
+        Plane at angle :math:`\theta_0` relative to the first basis axis
+    plane1 : openmc.Plane
+        Plane at angle :math:`\theta_0 + \theta` relative to the first
+        basis axis.
+
+    """
+
+    _surface_names = ('outer_cyl','inner_cyl',
+                      'plane0', 'plane1')
+
+    def __init__(self, center, r1, r2, theta0, theta, axis='z', **kwargs):
+        theta0 = pi / 180 * theta0
+        theta = pi / 180 * theta
+        theta1 = theta0 + theta
+
+        # Coords for axis-perpendicular planes
+        p1 = array([0.,0.,1.])
+
+        p2_plane0 = array([r1 * cos(theta0), r1 * sin(theta0), 0.])
+        p3_plane0 = array([r2 * cos(theta0), r2 * sin(theta0), 0.])
+
+        p2_plane1 = array([r1 * cos(theta1), r1 * sin(theta1), 0.])
+        p3_plane1 = array([r2 * cos(theta1), r2 * sin(theta1), 0.])
+
+        points = [p1, p2_plane0, p3_plane0, p2_plane1, p3_plane1]
+        if axis == 'z':
+            coord_map = [0,1,2]
+            self.inner_cyl = openmc.ZCylinder(*center, r1, **kwargs)
+            self.outer_cyl = openmc.ZCylinder(*center, r2, **kwargs)
+        elif axis == 'y':
+            coord_map = [1,2,0]
+            self.inner_cyl = openmc.YCylinder(*center, r1, **kwargs)
+            self.outer_cyl = openmc.YCylinder(*center, r2, **kwargs)
+        elif axis == 'x':
+            coord_map = [2,0,1]
+            self.inner_cyl = openmc.XCylinder(*center, r1, **kwargs)
+            self.outer_cyl = openmc.XCylinder(*center, r2, **kwargs)
+
+        for p in points:
+            p[:] = p[coord_map]
+
+        self.plane0 = openmc.Plane.from_points(p1, p2_plane0, p3_plane0,
+                                               **kwargs)
+        self.plane1 = openmc.Plane.from_points(p1, p2_plane1, p3_plane1,
+                                               **kwargs)
+
+    def __neg__(self):
+        return -self.outer_cyl & +self.inner_cyl & -self.plane0 &  +self.plane1
+
+    def __pos__(self):
+        return +self.outer_cyl | -self.inner_cyl | +self.plane0 | -self.plane1
+
+
 class RightCircularCylinder(CompositeSurface):
     """Right circular cylinder composite surface
 
@@ -167,100 +251,6 @@ class RectangularParallelepiped(CompositeSurface):
     def __pos__(self):
         return -self.xmin | +self.xmax | -self.ymin | +self.ymax | -self.zmin | +self.zmax
 
-class CylinderSector(CompositeSurface):
-    """Infinite cylindrical sector composite surface
-
-    This class acts as a proper surface, meaning that unary `+` and `-`
-    operators applied to it will produce a half-space. The negative
-    side is defined to be the region inside of the cylinder sector.
-
-    Parameters
-    ----------
-    center : iterable of float
-         Coordinate for central axes of cylinders in the (y, z), (x,z), or
-         (x, y) basis. Defaults to (0,0)
-    r1, r2 : float
-        Inner and outer cylinder radii
-    theta0 : float
-        Angular offset of the sector in degrees relative to the primary basis
-        axis (+y or +x).
-    theta : float
-        Angular width of the sector in degrees.
-    axis : {'z', 'y', 'x'}
-        Central axis of the cylinders. Defaults to z
-    **kwargs
-        Keyword arguments passed to underlying plane classes
-
-    Attributes
-    ----------
-    outer : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
-        Outer cylinder surface
-    inner : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
-        Inner cylinder surface
-    plane0 : openmc.Plane
-        Plane at angle :math:`\theta_0` relative to the first basis axis
-    plane1 : openmc.Plane
-        Plane at angle :math:`\theta_0 + \theta` relative to the first
-        basis axis.
-
-    """
-
-    _surface_names = ('outer_cyl','inner_cyl',
-                      'plane0', 'plane1')
-
-    def __init__(self, center, r1, r2, theta0, theta, axis='z', **kwargs):
-
-        self._axis = axis
-        theta0 = pi / 180 * theta0
-        theta = pi / 180 * theta
-        theta1 = theta0 + theta
-
-        # Coords for axis-perpendicular planes
-        p1 = array([0.,0.,1.])
-
-        p2_plane0 = array([r1 * cos(theta0), r1 * sin(theta0), 0.])
-        p3_plane0 = array([r2 * cos(theta0), r2 * sin(theta0), 0.])
-
-        p2_plane1 = array([r1 * cos(theta1), r1 * sin(theta1), 0.])
-        p3_plane1 = array([r2 * cos(theta1), r2 * sin(theta1), 0.])
-
-        points = [p1, p2_plane0, p3_plane0, p2_plane1, p3_plane1]
-        if axis == 'z':
-            coord_map = [0,1,2]
-            self.inner_cyl = openmc.ZCylinder(*center, r=r1, **kwargs)
-            self.outer_cyl = openmc.ZCylinder(*center, r=r2, **kwargs)
-        elif axis == 'y':
-            coord_map = [0,2,1]
-            self.inner_cyl = openmc.YCylinder(*center, r=r1, **kwargs)
-            self.outer_cyl = openmc.YCylinder(*center, r=r2, **kwargs)
-        elif axis == 'x':
-            coord_map = [2,0,1]
-            self.inner_cyl = openmc.XCylinder(*center, r=r1, **kwargs)
-            self.outer_cyl = openmc.XCylinder(*center, r=r2, **kwargs)
-
-        calibrated_points = []
-        for p in points:
-            calibrated_points += [p[coord_map]]
-
-        p1, p2_plane0, p3_plane0, p2_plane1, p3_plane1 = calibrated_points
-
-        self.plane0 = openmc.Plane.from_points(p1, p2_plane0, p3_plane0, **kwargs)
-        self.plane1 = openmc.Plane.from_points(p1, p2_plane1, p3_plane1, **kwargs)
-
-
-    def __neg__(self):
-        if self._axis == 'y':
-            return -self.outer_cyl & +self.inner_cyl & +self.plane0 &  -self.plane1
-        else:
-            return -self.outer_cyl & +self.inner_cyl & -self.plane0 &  +self.plane1
-
-
-    def __pos__(self):
-        if self._axis == 'y':
-            return +self.outer_cyl | -self.inner_cyl | -self.plane0 | +self.plane1
-        else:
-            return +self.outer_cyl | -self.inner_cyl | +self.plane0 | -self.plane1
-
 
 class XConeOneSided(CompositeSurface):
     """One-sided cone parallel the x-axis

From e341c20822b2cdadde9960b420ad619fa30eb2c7 Mon Sep 17 00:00:00 2001
From: yardasol <yardasol@grinnell.edu>
Date: Thu, 7 Apr 2022 11:36:04 -0500
Subject: [PATCH 09/24] pep8, consistency changes

---
 openmc/model/surface_composite.py | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 03595ff4b..7106730a8 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -1,7 +1,7 @@
 from abc import ABC, abstractmethod
 from copy import copy
 from math import sqrt, pi, sin, cos
-from numpy import array
+import numpy as np
 
 import openmc
 from openmc.checkvalue import check_greater_than, check_value
@@ -72,16 +72,16 @@ class CylinderSector(CompositeSurface):
         axis (+y, +z, or +x).
     theta : float
         Angular width of the sector in degrees.
-    axis : {'z', 'y', 'x'}
-        Central axis of the cylinders. Defaults to z
+    axis : {'x', 'y', 'z'}
+        Central axis of the cylinders. Defaults to 'z'.
     **kwargs
-        Keyword arguments passed to underlying plane classes
+        Keyword arguments passed to underlying plane classes.
 
     Attributes
     ----------
-    outer : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
+    outer_cyl : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
         Outer cylinder surface
-    inner : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
+    inner_cyl : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
         Inner cylinder surface
     plane0 : openmc.Plane
         Plane at angle :math:`\theta_0` relative to the first basis axis
@@ -100,7 +100,7 @@ class CylinderSector(CompositeSurface):
         theta1 = theta0 + theta
 
         # Coords for axis-perpendicular planes
-        p1 = array([0.,0.,1.])
+        p1 = array([0., 0., 1.])
 
         p2_plane0 = array([r1 * cos(theta0), r1 * sin(theta0), 0.])
         p3_plane0 = array([r2 * cos(theta0), r2 * sin(theta0), 0.])
@@ -110,15 +110,15 @@ class CylinderSector(CompositeSurface):
 
         points = [p1, p2_plane0, p3_plane0, p2_plane1, p3_plane1]
         if axis == 'z':
-            coord_map = [0,1,2]
+            coord_map = [0, 1, 2]
             self.inner_cyl = openmc.ZCylinder(*center, r1, **kwargs)
             self.outer_cyl = openmc.ZCylinder(*center, r2, **kwargs)
         elif axis == 'y':
-            coord_map = [1,2,0]
+            coord_map = [1, 2, 0]
             self.inner_cyl = openmc.YCylinder(*center, r1, **kwargs)
             self.outer_cyl = openmc.YCylinder(*center, r2, **kwargs)
         elif axis == 'x':
-            coord_map = [2,0,1]
+            coord_map = [2, 0, 1]
             self.inner_cyl = openmc.XCylinder(*center, r1, **kwargs)
             self.outer_cyl = openmc.XCylinder(*center, r2, **kwargs)
 

From 3340673dc58363e68d36c4f293698f48254dfe1a Mon Sep 17 00:00:00 2001
From: yardasol <yardasol@grinnell.edu>
Date: Thu, 7 Apr 2022 12:42:56 -0500
Subject: [PATCH 10/24] fix array syntax

---
 openmc/model/surface_composite.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 7106730a8..c82200128 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -100,13 +100,13 @@ class CylinderSector(CompositeSurface):
         theta1 = theta0 + theta
 
         # Coords for axis-perpendicular planes
-        p1 = array([0., 0., 1.])
+        p1 = np.array([0., 0., 1.])
 
-        p2_plane0 = array([r1 * cos(theta0), r1 * sin(theta0), 0.])
-        p3_plane0 = array([r2 * cos(theta0), r2 * sin(theta0), 0.])
+        p2_plane0 = np.array([r1 * cos(theta0), r1 * sin(theta0), 0.])
+        p3_plane0 = np.array([r2 * cos(theta0), r2 * sin(theta0), 0.])
 
-        p2_plane1 = array([r1 * cos(theta1), r1 * sin(theta1), 0.])
-        p3_plane1 = array([r2 * cos(theta1), r2 * sin(theta1), 0.])
+        p2_plane1 = np.array([r1 * cos(theta1), r1 * sin(theta1), 0.])
+        p3_plane1 = np.array([r2 * cos(theta1), r2 * sin(theta1), 0.])
 
         points = [p1, p2_plane0, p3_plane0, p2_plane1, p3_plane1]
         if axis == 'z':

From d08f2afa1c3bbc0cb3019523d07eba69bae60c82 Mon Sep 17 00:00:00 2001
From: yardasol <yardasol@grinnell.edu>
Date: Thu, 7 Apr 2022 13:32:58 -0500
Subject: [PATCH 11/24] docstring typo fixes

---
 openmc/model/surface_composite.py | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index c82200128..ec4143912 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -65,8 +65,10 @@ class CylinderSector(CompositeSurface):
     center : iterable of float
          Coordinate for central axes of cylinders in the (y, z), (z, x), or
          (x, y) basis. Defaults to (0,0)
-    r1, r2 : float
-        Inner and outer cylinder radii
+    r1 : float
+        Inner cylinder radii
+    r2 : float
+        Outer cylinder radii
     theta0 : float
         Angular offset of the sector in degrees relative to the primary basis
         axis (+y, +z, or +x).
@@ -84,9 +86,9 @@ class CylinderSector(CompositeSurface):
     inner_cyl : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
         Inner cylinder surface
     plane0 : openmc.Plane
-        Plane at angle :math:`\theta_0` relative to the first basis axis
+        Plane at angle :math:`\\theta_0` relative to the first basis axis
     plane1 : openmc.Plane
-        Plane at angle :math:`\theta_0 + \theta` relative to the first
+        Plane at angle :math:`\\theta_0 + \\theta` relative to the first
         basis axis.
 
     """

From 8e1880b01cb0039272eb063c9f82a501d3ee8d18 Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Thu, 7 Apr 2022 19:00:57 -0500
Subject: [PATCH 12/24] formatting fixes

---
 openmc/model/surface_composite.py          |  9 ++++-----
 tests/unit_tests/test_surface_composite.py | 10 ++++++----
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 70cdb33e1..e1696edce 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -58,10 +58,10 @@ class CylinderSector(CompositeSurface):
     This class acts as a proper surface, meaning that unary `+` and `-`
     operators applied to it will produce a half-space. The negative
     side is defined to be the region inside of the cylinder sector.
-     
+
     Parameters
     ----------
-    center : iterable of float   
+    center : iterable of float
        Coordinate for central axes of cylinders in the (y, z), (z, x), or
          (x, y) basis. Defaults to (0,0)
     r1 : float
@@ -136,8 +136,8 @@ class CylinderSector(CompositeSurface):
 
     def __pos__(self):
         return +self.outer_cyl | -self.inner_cyl | +self.plane0 | -self.plane1
-      
-      
+
+
 class IsogonalOctagon(CompositeSurface):
     """Infinite isogonal octagon composite surface
 
@@ -155,7 +155,6 @@ class IsogonalOctagon(CompositeSurface):
     Parameters
     ----------
     center : iterable of float
-
         Coordinate for the central axis of the octagon in the
         (y, z), (z, x), or (x, y) basis.
     r1 : float
diff --git a/tests/unit_tests/test_surface_composite.py b/tests/unit_tests/test_surface_composite.py
index f7dbeca4e..6b9b6c7a5 100644
--- a/tests/unit_tests/test_surface_composite.py
+++ b/tests/unit_tests/test_surface_composite.py
@@ -171,7 +171,7 @@ def test_cylinder_sector(axis, indices):
     assert isinstance(s.inner_cyl, getattr(openmc, axis + "Cylinder"))
     assert isinstance(s.plane0, openmc.Plane)
     assert isinstance(s.plane1, openmc.Plane)
-    
+
     # Make sure boundary condition propagates
     s.boundary_type = 'reflective'
     assert s.boundary_type == 'reflective'
@@ -179,7 +179,7 @@ def test_cylinder_sector(axis, indices):
     assert s.inner_cyl.boundary_type == 'reflective'
     assert s.plane0.boundary_type == 'reflective'
     assert s.plane1.boundary_type == 'reflective'
-    
+
     # Check bounding box
     ll, ur = (+s).bounding_box
     assert np.all(np.isinf(ll))
@@ -237,7 +237,7 @@ def test_isogonal_octagon(axis, plane_tb, plane_lr, axis_idx):
     assert isinstance(s.lower_right, openmc.Plane)
     assert isinstance(s.upper_left, openmc.Plane)
     assert isinstance(s.lower_left, openmc.Plane)
-    
+
     # Make sure boundary condition propagates
     s.boundary_type = 'reflective'
     assert s.boundary_type == 'reflective'
@@ -285,4 +285,6 @@ def test_isogonal_octagon(axis, plane_tb, plane_lr, axis_idx):
         openmc.model.IsogonalOctagon(center, r1=10., r2=1.)
 
     # Make sure repr works
-    repr(s)
\ No newline at end of file
+    repr(s)
+
+

From e53be38712630b684019469cafd25497716ece48 Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Thu, 7 Apr 2022 19:01:09 -0500
Subject: [PATCH 13/24] pep8 fixes

---
 openmc/model/surface_composite.py          | 9 +++++----
 tests/unit_tests/test_surface_composite.py | 5 ++---
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index e1696edce..e3ac7e345 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -6,6 +6,7 @@ import numpy as np
 import openmc
 from openmc.checkvalue import check_greater_than, check_value
 
+
 class CompositeSurface(ABC):
     """Multiple primitive surfaces combined into a composite surface"""
 
@@ -92,7 +93,7 @@ class CylinderSector(CompositeSurface):
 
     """
 
-    _surface_names = ('outer_cyl','inner_cyl',
+    _surface_names = ('outer_cyl', 'inner_cyl',
                       'plane0', 'plane1')
 
     def __init__(self, center, r1, r2, theta0, theta, axis='z', **kwargs):
@@ -132,7 +133,7 @@ class CylinderSector(CompositeSurface):
                                                **kwargs)
 
     def __neg__(self):
-        return -self.outer_cyl & +self.inner_cyl & -self.plane0 &  +self.plane1
+        return -self.outer_cyl & +self.inner_cyl & -self.plane0 & +self.plane1
 
     def __pos__(self):
         return +self.outer_cyl | -self.inner_cyl | +self.plane0 | -self.plane1
@@ -206,10 +207,10 @@ class IsogonalOctagon(CompositeSurface):
 
         # Side lengths
         if r2 > r1 * sqrt(2):
-            raise ValueError(f'r2 is greater than sqrt(2) * r1. Octagon' + \
+            raise ValueError(f'r2 is greater than sqrt(2) * r1. Octagon' +
                              ' may be erroneous.')
         if r1 > r2 * sqrt(2):
-            raise ValueError(f'r1 is greater than sqrt(2) * r2. Octagon' + \
+            raise ValueError(f'r1 is greater than sqrt(2) * r2. Octagon' +
                              ' may be erroneous.')
 
         L_basis_ax = (r2 * sqrt(2) - r1)
diff --git a/tests/unit_tests/test_surface_composite.py b/tests/unit_tests/test_surface_composite.py
index 6b9b6c7a5..7985a2aae 100644
--- a/tests/unit_tests/test_surface_composite.py
+++ b/tests/unit_tests/test_surface_composite.py
@@ -12,7 +12,8 @@ def test_rectangular_parallelepiped():
     ymax = ymin + uniform(0., 5.)
     zmin = uniform(-5., 5.)
     zmax = zmin + uniform(0., 5.)
-    s = openmc.model.RectangularParallelepiped(xmin, xmax, ymin, ymax, zmin, zmax)
+    s = openmc.model.RectangularParallelepiped(
+        xmin, xmax, ymin, ymax, zmin, zmax)
     assert isinstance(s.xmin, openmc.XPlane)
     assert isinstance(s.xmax, openmc.XPlane)
     assert isinstance(s.ymin, openmc.YPlane)
@@ -286,5 +287,3 @@ def test_isogonal_octagon(axis, plane_tb, plane_lr, axis_idx):
 
     # Make sure repr works
     repr(s)
-
-

From 3c2f0c03ffdce64c72b51202c089cc804b82df7b Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Tue, 26 Apr 2022 13:32:14 -0500
Subject: [PATCH 14/24] apply feedback from @paulromano: add checks for sector
 bounds; make variables less ambiguous

---
 openmc/model/surface_composite.py          | 59 ++++++++++++----------
 tests/unit_tests/test_surface_composite.py | 20 +++++---
 2 files changed, 45 insertions(+), 34 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index e3ac7e345..7a6a50ba4 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -66,16 +66,18 @@ class CylinderSector(CompositeSurface):
        Coordinate for central axes of cylinders in the (y, z), (z, x), or
          (x, y) basis. Defaults to (0,0)
     r1 : float
-        Inner cylinder radii
+        Inner radius of sector. Must be less than r2.
     r2 : float
-        Outer cylinder radii
-    theta0 : float
-        Angular offset of the sector in degrees relative to the primary basis
-        axis (+y, +z, or +x).
-    theta : float
-        Angular width of the sector in degrees.
+        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 of the clockwise-most side of the sector in degrees
+        relative to the primary basis axis (+y, +z, or +x).
     axis : {'x', 'y', 'z'}
-        Central axis of the cylinders. Defaults to 'z'.
+        Central axis of the cylinders defining the inner and outer surfaces
+        of the sector. Defaults to 'z'.
     **kwargs
         Keyword arguments passed to underlying plane classes.
 
@@ -85,32 +87,37 @@ class CylinderSector(CompositeSurface):
         Outer cylinder surface
     inner_cyl : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
         Inner cylinder surface
-    plane0 : openmc.Plane
-        Plane at angle :math:`\\theta_0` relative to the first basis axis
     plane1 : openmc.Plane
-        Plane at angle :math:`\\theta_0 + \\theta` relative to the first
+        Plane at angle :math:`\\phi_1 = \\alpha` relative to the first basis axis
+    plane2 : openmc.Plane
+        Plane at angle :math:`\\phi_2 = \\alpha + \\theta` relative to the first
         basis axis.
 
     """
 
-    _surface_names = ('outer_cyl', 'inner_cyl',
-                      'plane0', 'plane1')
+    _surface_names = ('outer_cyl', 'inner_cyl', 'plane1', 'plane2')
 
-    def __init__(self, center, r1, r2, theta0, theta, axis='z', **kwargs):
-        theta0 = pi / 180 * theta0
-        theta = pi / 180 * theta
-        theta1 = theta0 + theta
+    def __init__(self, center, r1, r2, central_angle, alpha, axis='z', **kwargs):
+
+        if r2 <= r1 * sqrt(2):
+            raise ValueError(f'r2 must be greater than r1.')
+
+        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)
 
         # Coords for axis-perpendicular planes
         p1 = np.array([0., 0., 1.])
 
-        p2_plane0 = np.array([r1 * cos(theta0), r1 * sin(theta0), 0.])
-        p3_plane0 = np.array([r2 * cos(theta0), r2 * sin(theta0), 0.])
+        p2_plane1 = np.array([r1 * cos(phi1), r1 * sin(phi1), 0.])
+        p3_plane1 = np.array([r2 * cos(phi1), r2 * sin(phi1), 0.])
 
-        p2_plane1 = np.array([r1 * cos(theta1), r1 * sin(theta1), 0.])
-        p3_plane1 = np.array([r2 * cos(theta1), r2 * sin(theta1), 0.])
+        p2_plane2 = np.array([r1 * cos(phi2), r1 * sin(phi2), 0.])
+        p3_plane2 = np.array([r2 * cos(phi2), r2 * sin(phi2), 0.])
 
-        points = [p1, p2_plane0, p3_plane0, p2_plane1, p3_plane1]
+        points = [p1, p2_plane1, p3_plane1, p2_plane2, p3_plane2]
         if axis == 'z':
             coord_map = [0, 1, 2]
             self.inner_cyl = openmc.ZCylinder(*center, r1, **kwargs)
@@ -127,16 +134,16 @@ class CylinderSector(CompositeSurface):
         for p in points:
             p[:] = p[coord_map]
 
-        self.plane0 = openmc.Plane.from_points(p1, p2_plane0, p3_plane0,
-                                               **kwargs)
         self.plane1 = openmc.Plane.from_points(p1, p2_plane1, p3_plane1,
                                                **kwargs)
+        self.plane2 = openmc.Plane.from_points(p1, p2_plane2, p3_plane2,
+                                               **kwargs)
 
     def __neg__(self):
-        return -self.outer_cyl & +self.inner_cyl & -self.plane0 & +self.plane1
+        return -self.outer_cyl & +self.inner_cyl & -self.plane1 & +self.plane2
 
     def __pos__(self):
-        return +self.outer_cyl | -self.inner_cyl | +self.plane0 | -self.plane1
+        return +self.outer_cyl | -self.inner_cyl | +self.plane1 | -self.plane2
 
 
 class IsogonalOctagon(CompositeSurface):
diff --git a/tests/unit_tests/test_surface_composite.py b/tests/unit_tests/test_surface_composite.py
index 7985a2aae..00e51e6d9 100644
--- a/tests/unit_tests/test_surface_composite.py
+++ b/tests/unit_tests/test_surface_composite.py
@@ -164,22 +164,22 @@ def test_cylinder_sector(axis, indices):
     center = [0., 0.]
     r1, r2 = 0.5, 1.5
     d = (r2 - r1) / 2
-    theta0 = -60.
-    theta = 120.
-    s = openmc.model.CylinderSector(center, r1, r2, theta0, theta,
+    central_angle = 120.
+    alpha = -60.
+    s = openmc.model.CylinderSector(center, r1, r2, central_angle, alpha,
                                     axis=axis.lower())
     assert isinstance(s.outer_cyl, getattr(openmc, axis + "Cylinder"))
     assert isinstance(s.inner_cyl, getattr(openmc, axis + "Cylinder"))
-    assert isinstance(s.plane0, openmc.Plane)
     assert isinstance(s.plane1, openmc.Plane)
+    assert isinstance(s.plane2, openmc.Plane)
 
     # Make sure boundary condition propagates
     s.boundary_type = 'reflective'
     assert s.boundary_type == 'reflective'
     assert s.outer_cyl.boundary_type == 'reflective'
     assert s.inner_cyl.boundary_type == 'reflective'
-    assert s.plane0.boundary_type == 'reflective'
     assert s.plane1.boundary_type == 'reflective'
+    assert s.plane2.boundary_type == 'reflective'
 
     # Check bounding box
     ll, ur = (+s).bounding_box
@@ -193,7 +193,7 @@ def test_cylinder_sector(axis, indices):
     point_pos = np.roll([0, r2 + 1, 0], indices[0])
     assert point_pos in +s
     assert point_pos not in -s
-    point_neg = np.roll([0, r1 + d/2, r1 + d/2], indices[0])
+    point_neg = np.roll([0, r1 + d, r1 + d], indices[0])
     assert point_neg in -s
     assert point_neg not in +s
 
@@ -206,9 +206,13 @@ def test_cylinder_sector(axis, indices):
 
     # Check invalid r1, r2 combinations
     with pytest.raises(ValueError):
-        openmc.model.IsogonalOctagon(center, r1=1.0, r2=10.)
+        openmc.model.CylinderSector(center, 10., 1., central_angle, alpha)
+
+    # Check invalid sector width
     with pytest.raises(ValueError):
-        openmc.model.IsogonalOctagon(center, r1=10., r2=1.)
+        openmc.model.CylinderSector(center, 1., 10., 360, alpha)
+    with pytest.raises(ValueError):
+        openmc.model.CylinderSector(center, 1., 10., -1, alpha)
 
     # Make sure repr works
     repr(s)

From 020e0bd945ee9ac3a385c6ae02cf25239cbd7dae Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Tue, 26 Apr 2022 13:33:04 -0500
Subject: [PATCH 15/24] minor docstring addition

---
 openmc/model/surface_composite.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 7a6a50ba4..3b4a1f42f 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -73,7 +73,7 @@ class CylinderSector(CompositeSurface):
         Central angle, :math:`\\theta`, of the sector in degrees. Must be greater
         that 0 and less than 360.
     alpha : float
-        Angular offset of the clockwise-most side of the sector in degrees
+        Angular offset, :math:`\\alpha`, of the clockwise-most side of the sector in degrees
         relative to the primary basis axis (+y, +z, or +x).
     axis : {'x', 'y', 'z'}
         Central axis of the cylinders defining the inner and outer surfaces

From be97beb1c44ed4f46c175454a940a4e15a80f696 Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Tue, 26 Apr 2022 13:41:50 -0500
Subject: [PATCH 16/24] make description of 'first basis axis' consistent'

---
 openmc/model/surface_composite.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 3b4a1f42f..9a44d1955 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -74,7 +74,7 @@ class CylinderSector(CompositeSurface):
         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 primary basis axis (+y, +z, or +x).
+        relative to the first basis axis (+y, +z, or +x).
     axis : {'x', 'y', 'z'}
         Central axis of the cylinders defining the inner and outer surfaces
         of the sector. Defaults to 'z'.

From 5abd01d4df7534b7be6aee8723791c6706afdd80 Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Tue, 26 Apr 2022 13:49:21 -0500
Subject: [PATCH 17/24] add description of surfaces

---
 openmc/model/surface_composite.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 9a44d1955..c39439ed3 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -56,6 +56,10 @@ class CompositeSurface(ABC):
 class CylinderSector(CompositeSurface):
     """Infinite cylindrical sector composite surface
 
+    A cylinder sector is composed of two cylindrical and two planar surfaces.
+    The cylindrical surfaces are concentric, and the planar surfaces intersect
+    the central axis of the cylindrical surfaces.
+
     This class acts as a proper surface, meaning that unary `+` and `-`
     operators applied to it will produce a half-space. The negative
     side is defined to be the region inside of the cylinder sector.

From 09711e9672cbdd50682c20af8575da2db5e8c541 Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Tue, 26 Apr 2022 14:05:47 -0500
Subject: [PATCH 18/24] alpha -> ccw_offset; consistency changes

---
 openmc/model/surface_composite.py          | 25 +++++++++++++++-------
 tests/unit_tests/test_surface_composite.py | 10 ++++-----
 2 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index c39439ed3..5ad87d719 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 00e51e6d9..458f11c60 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)

From 3cb3f9e673bca24a95f3c35aab65a415e3ba0905 Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Tue, 26 Apr 2022 14:26:11 -0500
Subject: [PATCH 19/24] clean up run-on sentence for ccw_offset; fix formatting
 in description for center

---
 openmc/model/surface_composite.py | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 5ad87d719..0f62c07ac 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -67,8 +67,8 @@ class CylinderSector(CompositeSurface):
     Parameters
     ----------
     center : iterable of float
-       Coordinate for central axes of cylinders in the (y, z), (z, x), or
-         (x, y) basis. Defaults to (0,0)
+       Coordinate for central axes of cylinders in the (y, z), (z, x), or (x, y)
+       basis. Defaults to (0,0)
     r1 : float
         Inner radius of sector. Must be less than r2.
     r2 : float
@@ -77,13 +77,13 @@ class CylinderSector(CompositeSurface):
         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.
+        Angular offset, :math:`\\alpha`, of the clockwise-most side of the
+        sector in degrees. The offset is in the counter-clockwise direction
+        with respect to the first basis axis (+y, +z, or +x). Note that
+        negative values translate to an offset in the clockwise direction.
     axis : {'x', 'y', 'z'}
-        Central axis of the cylinders defining the inner and outer surfaces
-        of the sector. Defaults to 'z'.
+        Central axis of the cylinders defining the inner and outer surfaces of
+        the sector. Defaults to 'z'.
     **kwargs
         Keyword arguments passed to underlying plane classes.
 

From fc3809c2df6d5705b5167276a39dd0cd98faf199 Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Tue, 26 Apr 2022 14:28:08 -0500
Subject: [PATCH 20/24] add periods

---
 openmc/model/surface_composite.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 0f62c07ac..af84670cf 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -54,7 +54,7 @@ class CompositeSurface(ABC):
 
 
 class CylinderSector(CompositeSurface):
-    """Infinite cylindrical sector composite surface
+    """Infinite cylindrical sector composite surface.
 
     A cylinder sector is composed of two cylindrical and two planar surfaces.
     The cylindrical surfaces are concentric, and the planar surfaces intersect
@@ -68,7 +68,7 @@ class CylinderSector(CompositeSurface):
     ----------
     center : iterable of float
        Coordinate for central axes of cylinders in the (y, z), (z, x), or (x, y)
-       basis. Defaults to (0,0)
+       basis. Defaults to (0,0).
     r1 : float
         Inner radius of sector. Must be less than r2.
     r2 : float
@@ -90,11 +90,11 @@ class CylinderSector(CompositeSurface):
     Attributes
     ----------
     outer_cyl : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
-        Outer cylinder surface
+        Outer cylinder surface.
     inner_cyl : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
-        Inner cylinder surface
+        Inner cylinder surface.
     plane1 : openmc.Plane
-        Plane at angle :math:`\\phi_1 = \\alpha` relative to the first basis axis
+        Plane at angle :math:`\\phi_1 = \\alpha` relative to the first basis axis.
     plane2 : openmc.Plane
         Plane at angle :math:`\\phi_2 = \\alpha + \\theta` relative to the first
         basis axis.

From 51e5d1ccd2ce7b08953c4bb24314e884345e352d Mon Sep 17 00:00:00 2001
From: yardasol <yardasol@grinnell.edu>
Date: Wed, 27 Apr 2022 12:56:39 -0500
Subject: [PATCH 21/24] make theta1,theta2 formulation the default; add
 alternate constructor for theta,alpha formulation

---
 openmc/model/surface_composite.py          | 102 ++++++++++++++++-----
 tests/unit_tests/test_surface_composite.py |  36 ++++++--
 2 files changed, 106 insertions(+), 32 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index af84670cf..d4b25436d 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -66,26 +66,27 @@ class CylinderSector(CompositeSurface):
 
     Parameters
     ----------
-    center : iterable of float
-       Coordinate for central axes of cylinders in the (y, z), (z, x), or (x, y)
-       basis. Defaults to (0,0).
     r1 : float
         Inner radius of sector. Must be less than r2.
     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.
-    ccw_offset : float
-        Angular offset, :math:`\\alpha`, of the clockwise-most side of the
-        sector in degrees. The offset is in the counter-clockwise direction
-        with respect to the first basis axis (+y, +z, or +x). Note that
-        negative values translate to an offset in the clockwise direction.
+    theta1 : float
+        Clockwise-most bound of sector in degrees. Assumed to be in the
+        counterclockwise direction with respect to the first basis axis
+        (+y, +z, or +x). Must be less than :attr:`theta2`.
+    theta2 : float
+        Counterclockwise-most bound of sector in degrees. Assumed to be in the
+        counterclockwise direction with respect to the first basis axis
+        (+y, +z, or +x). Must be greater than :attr:`theta1`.
+    center : iterable of float
+       Coordinate for central axes of cylinders in the (y, z), (z, x), or (x, y)
+       basis. Defaults to (0,0).
+
     axis : {'x', 'y', 'z'}
         Central axis of the cylinders defining the inner and outer surfaces of
         the sector. Defaults to 'z'.
-    **kwargs
-        Keyword arguments passed to underlying plane classes.
+    kwargs : dict
+            Keyword arguments passed to the :class:`Cylinder` and :class:`Plane` constructors.
 
     Attributes
     ----------
@@ -94,32 +95,34 @@ class CylinderSector(CompositeSurface):
     inner_cyl : openmc.ZCylinder, openmc.YCylinder, or openmc.XCylinder
         Inner cylinder surface.
     plane1 : openmc.Plane
-        Plane at angle :math:`\\phi_1 = \\alpha` relative to the first basis axis.
+        Plane at angle :math:`\\theta_1` relative to the first basis axis.
     plane2 : openmc.Plane
-        Plane at angle :math:`\\phi_2 = \\alpha + \\theta` relative to the first
-        basis axis.
+        Plane at angle :math:`\\theta_2` relative to the first basis axis.
 
     """
 
     _surface_names = ('outer_cyl', 'inner_cyl', 'plane1', 'plane2')
 
     def __init__(self,
-                 center,
                  r1,
                  r2,
-                 central_angle,
-                 ccw_offset,
+                 theta1,
+                 theta2,
+                 center=(0.,0.),
                  axis='z',
                  **kwargs):
 
         if r2 <= r1 * sqrt(2):
             raise ValueError(f'r2 must be greater than r1.')
 
-        if central_angle >= 360. or central_angle <= 0:
-            raise ValueError(f'theta must be less than 360.')
+        if theta2 <= theta1:
+            raise ValueError(f'theta2 must be greater than theta1.')
 
-        phi1 = pi / 180 * ccw_offset
-        phi2 = pi / 180 * (ccw_offset + central_angle)
+        self._theta1 = theta1
+        self._theta2 = theta2
+
+        phi1 = pi / 180 * theta1
+        phi2 = pi / 180 * theta2
 
         # Coords for axis-perpendicular planes
         p1 = np.array([0., 0., 1.])
@@ -152,6 +155,59 @@ class CylinderSector(CompositeSurface):
         self.plane2 = openmc.Plane.from_points(p1, p2_plane2, p3_plane2,
                                                **kwargs)
 
+    @classmethod
+    def from_theta_alpha(cls,
+                         r1,
+                         r2,
+                         theta,
+                         alpha,
+                         center = (0.,0.),
+                         axis='z',
+                         **kwargs):
+        """Alternate constructor for :attr:`CylinderSector`. Returns an
+        :attr:`CylinderSector` object based on a central angle :math:`\\theta`
+        and an angular offset :math:`\\alpha`. Note that
+        :math:`\\theta_1 = \\alpha` and :math:`\\theta_2 = \\alpha + \\theta`.
+
+        Parameters
+        ----------
+        r1 : float
+            Inner radius of sector. Must be less than r2.
+        r2 : float
+            Outer radius of sector. Must be greater than r1.
+        theta : 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 sector in degrees.
+            The offset is in the counter-clockwise direction
+            with respect to the first basis axis (+y, +z, or +x). Note that
+            negative values translate to an offset in the clockwise direction.
+        center : iterable of float
+            Coordinate for central axes of cylinders in the (y, z), (z, x), or (x, y)
+            basis. Defaults to (0,0).
+
+        axis : {'x', 'y', 'z'}
+            Central axis of the cylinders defining the inner and outer surfaces of
+            the sector. Defaults to 'z'.
+
+        kwargs : dict
+            Keyword arguments passed to the :class:`Cylinder` and :class:`Plane` constructors.
+
+        Returns
+        -------
+        CylinderSector
+            CylinderSector with the given central angle at the given
+            offset.
+        """
+        if theta >= 360. or theta <= 0:
+            raise ValueError(f'theta must be less than 360 and greater than 0.')
+
+        theta1 = alpha
+        theta2 = alpha + theta
+
+        return cls(r1, r2, theta1, theta2, center=center, axis=axis, **kwargs)
+
     def __neg__(self):
         return -self.outer_cyl & +self.inner_cyl & -self.plane1 & +self.plane2
 
diff --git a/tests/unit_tests/test_surface_composite.py b/tests/unit_tests/test_surface_composite.py
index 458f11c60..d4c180d26 100644
--- a/tests/unit_tests/test_surface_composite.py
+++ b/tests/unit_tests/test_surface_composite.py
@@ -161,12 +161,11 @@ def test_cone_one_sided(axis, point_pos, point_neg, ll_true):
     ]
 )
 def test_cylinder_sector(axis, indices):
-    center = [0., 0.]
     r1, r2 = 0.5, 1.5
     d = (r2 - r1) / 2
-    central_angle = 120.
-    ccw_offset = -60.
-    s = openmc.model.CylinderSector(center, r1, r2, central_angle, ccw_offset,
+    phi1 = -60.
+    phi2 = 60
+    s = openmc.model.CylinderSector(r1, r2, phi1, phi2,
                                     axis=axis.lower())
     assert isinstance(s.outer_cyl, getattr(openmc, axis + "Cylinder"))
     assert isinstance(s.inner_cyl, getattr(openmc, axis + "Cylinder"))
@@ -206,18 +205,37 @@ def test_cylinder_sector(axis, indices):
 
     # Check invalid r1, r2 combinations
     with pytest.raises(ValueError):
-        openmc.model.CylinderSector(center, 10., 1., central_angle, ccw_offset)
+        openmc.model.CylinderSector(r2, r1, phi1, phi2)
 
-    # Check invalid sector width
+    # Check invalid angles
     with pytest.raises(ValueError):
-        openmc.model.CylinderSector(center, 1., 10., 360, ccw_offset)
-    with pytest.raises(ValueError):
-        openmc.model.CylinderSector(center, 1., 10., -1, ccw_offset)
+        openmc.model.CylinderSector(r1, r2, phi2, phi1)
 
     # Make sure repr works
     repr(s)
 
 
+def test_cylinder_sector_from_theta_alpha():
+    r1, r2 = 0.5, 1.5
+    d = (r2 - r1) / 2
+    theta = 120.
+    alpha = -60.
+    s = openmc.model.CylinderSector.from_theta_alpha(r1,
+                                                     r2,
+                                                     theta,
+                                                     alpha)
+
+    # Check that the angles are correct
+    assert s._theta1 == alpha
+    assert s._theta2 == alpha + theta
+
+    # Check invalid sector width
+    with pytest.raises(ValueError):
+        openmc.model.CylinderSector.from_theta_alpha(r1, r2, 360, alpha)
+    with pytest.raises(ValueError):
+        openmc.model.CylinderSector.from_theta_alpha(r1, r2, -1, alpha)
+
+
 @pytest.mark.parametrize(
     "axis, plane_tb, plane_lr, axis_idx", [
         ("x", "Z", "Y", 0),

From 1d7265de3ea1012bfa935a48ec96384897847b03 Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Thu, 28 Apr 2022 10:24:31 -0500
Subject: [PATCH 22/24] check surface coefficients match between CylinderSector
 objects from different constructors

---
 tests/unit_tests/test_surface_composite.py | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/tests/unit_tests/test_surface_composite.py b/tests/unit_tests/test_surface_composite.py
index d4c180d26..4d680ae7c 100644
--- a/tests/unit_tests/test_surface_composite.py
+++ b/tests/unit_tests/test_surface_composite.py
@@ -220,14 +220,19 @@ def test_cylinder_sector_from_theta_alpha():
     d = (r2 - r1) / 2
     theta = 120.
     alpha = -60.
-    s = openmc.model.CylinderSector.from_theta_alpha(r1,
+    theta1 = alpha
+    theta2 = alpha + theta
+    s = openmc.model.CylinderSector(r1, r2, theta1, theta2)
+    s_alt = openmc.model.CylinderSector.from_theta_alpha(r1,
                                                      r2,
                                                      theta,
                                                      alpha)
 
     # Check that the angles are correct
-    assert s._theta1 == alpha
-    assert s._theta2 == alpha + theta
+    assert s.plane1.coefficients == s_alt.plane1.coefficients
+    assert s.plane2.coefficients == s_alt.plane2.coefficients
+    assert s.inner_cyl.coefficients == s_alt.inner_cyl.coefficients
+    assert s.outer_cyl.coefficients == s_alt.outer_cyl.coefficients
 
     # Check invalid sector width
     with pytest.raises(ValueError):

From 2cccc1b788d8dfee99b805e05eab089ff895f4f4 Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Thu, 28 Apr 2022 10:26:58 -0500
Subject: [PATCH 23/24] docstring fixes for from_theta_alpha; remove cruft
 attributes

---
 openmc/model/surface_composite.py | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index d4b25436d..590fe13a4 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -112,15 +112,12 @@ class CylinderSector(CompositeSurface):
                  axis='z',
                  **kwargs):
 
-        if r2 <= r1 * sqrt(2):
+        if r2 <= r1:
             raise ValueError(f'r2 must be greater than r1.')
 
         if theta2 <= theta1:
             raise ValueError(f'theta2 must be greater than theta1.')
 
-        self._theta1 = theta1
-        self._theta2 = theta2
-
         phi1 = pi / 180 * theta1
         phi2 = pi / 180 * theta2
 
@@ -164,10 +161,10 @@ class CylinderSector(CompositeSurface):
                          center = (0.,0.),
                          axis='z',
                          **kwargs):
-        """Alternate constructor for :attr:`CylinderSector`. Returns an
-        :attr:`CylinderSector` object based on a central angle :math:`\\theta`
-        and an angular offset :math:`\\alpha`. Note that
-        :math:`\\theta_1 = \\alpha` and :math:`\\theta_2 = \\alpha + \\theta`.
+        r"""Alternate constructor for :class:`CylinderSector`. Returns a
+        :class:`CylinderSector` object based on a central angle :math:`\theta`
+        and an angular offset :math:`\alpha`. Note that
+        :math:`\theta_1 = \alpha` and :math:`\theta_2 = \alpha + \theta`.
 
         Parameters
         ----------
@@ -176,22 +173,20 @@ class CylinderSector(CompositeSurface):
         r2 : float
             Outer radius of sector. Must be greater than r1.
         theta : float
-            Central angle, :math:`\\theta`, of the sector in degrees. Must be
+            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 sector in degrees.
+            Angular offset, :math:`\alpha`, of sector in degrees.
             The offset is in the counter-clockwise direction
             with respect to the first basis axis (+y, +z, or +x). Note that
             negative values translate to an offset in the clockwise direction.
         center : iterable of float
             Coordinate for central axes of cylinders in the (y, z), (z, x), or (x, y)
             basis. Defaults to (0,0).
-
         axis : {'x', 'y', 'z'}
             Central axis of the cylinders defining the inner and outer surfaces of
             the sector. Defaults to 'z'.
-
-        kwargs : dict
+        **kwargs : dict
             Keyword arguments passed to the :class:`Cylinder` and :class:`Plane` constructors.
 
         Returns

From 77b4ec564718e8c876ac1ec4dbc83c9adc2d5921 Mon Sep 17 00:00:00 2001
From: yardasol <oyardas2@illinois.edu>
Date: Thu, 28 Apr 2022 10:30:47 -0500
Subject: [PATCH 24/24] pep8 and consistency fixes in docstring

---
 openmc/model/surface_composite.py | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/openmc/model/surface_composite.py b/openmc/model/surface_composite.py
index 590fe13a4..74f64c54a 100644
--- a/openmc/model/surface_composite.py
+++ b/openmc/model/surface_composite.py
@@ -81,12 +81,12 @@ class CylinderSector(CompositeSurface):
     center : iterable of float
        Coordinate for central axes of cylinders in the (y, z), (z, x), or (x, y)
        basis. Defaults to (0,0).
-
     axis : {'x', 'y', 'z'}
         Central axis of the cylinders defining the inner and outer surfaces of
         the sector. Defaults to 'z'.
-    kwargs : dict
-            Keyword arguments passed to the :class:`Cylinder` and :class:`Plane` constructors.
+    **kwargs : dict
+        Keyword arguments passed to the :class:`Cylinder` and
+        :class:`Plane` constructors.
 
     Attributes
     ----------
@@ -184,10 +184,11 @@ class CylinderSector(CompositeSurface):
             Coordinate for central axes of cylinders in the (y, z), (z, x), or (x, y)
             basis. Defaults to (0,0).
         axis : {'x', 'y', 'z'}
-            Central axis of the cylinders defining the inner and outer surfaces of
-            the sector. Defaults to 'z'.
+            Central axis of the cylinders defining the inner and outer surfaces
+            of the sector. Defaults to 'z'.
         **kwargs : dict
-            Keyword arguments passed to the :class:`Cylinder` and :class:`Plane` constructors.
+            Keyword arguments passed to the :class:`Cylinder` and
+            :class:`Plane` constructors.
 
         Returns
         -------