diff --git a/documentation/source/eng-models/central-solenoid.md b/documentation/source/eng-models/central-solenoid.md
index fae589980a..a89de20998 100644
--- a/documentation/source/eng-models/central-solenoid.md
+++ b/documentation/source/eng-models/central-solenoid.md
@@ -433,7 +433,7 @@ solenoid usually consists of several coils, which can have opposite currents.  T
 forces that tend to separate the coils.  To prevent this, ITER has "tie-plates" which hold the coil 
 segments together.  PROCESS has a corresponding structure, known as the pre-compression structure, 
 made up of two cylinders, one on the inside and one on the outside, of the same thickness. The 
-radii of the two cylinders are `dr_bore` and `dr_bore` + `dr_cs`.  The thickness is derived using the 
+radii of the two cylinders are `dr_cs_bore` and `dr_cs_bore` + `dr_cs`.  The thickness is derived using the 
 separation force and the combined cross-sectional area:
 
 $$
diff --git a/process/core/io/plot/summary.py b/process/core/io/plot/summary.py
index 536c671b65..7f71600954 100644
--- a/process/core/io/plot/summary.py
+++ b/process/core/io/plot/summary.py
@@ -2664,12 +2664,12 @@ def plot_main_plasma_information(
         f"Extra heat power: {mfile.get('p_hcd_secondary_extra_heat_mw', scan=scan):.4f} MW\n"
         f"$\\eta_{{\\text{{CD,sec}}}}$: {mfile.get('eta_cd_hcd_secondary', scan=scan):.4f} A/W  |   $\\langle\\zeta_{{\\text{{CD,sec}}}}\\rangle$: {mfile.get('eta_cd_dimensionless_hcd_secondary', scan=scan):.4f}  \n"
         f"$\\gamma_{{\\text{{CD,sec}}}}$: {mfile.get('eta_cd_norm_hcd_secondary', scan=scan):.4f} $\\times 10^{{20}}  \\mathrm{{A}} / \\mathrm{{Wm}}^2$\n"
-        f"Current driven by secondary: {mfile.get('c_hcd_secondary_driven', scan=scan) / 1e6:.3f} MA\n"
+        f"Current driven by secondary: {mfile.get('c_hcd_secondary_driven', scan=scan) / 1e6:.3f} MA"
     )
 
     axis.text(
-        0.66,
-        0.6,
+        0.73,
+        0.675,
         textstr_hcd,
         fontsize=9,
         verticalalignment="top",
@@ -7948,7 +7948,7 @@ def plot_pf_coils(
     coils_dz = []
     coil_text = []
 
-    dr_bore = mfile.get("dr_bore", scan=scan)
+    dr_cs_bore = mfile.get("dr_cs_bore", scan=scan)
     dr_cs = mfile.get("dr_cs", scan=scan)
     dz_cs_full = mfile.get("dz_cs_full", scan=scan)
 
@@ -7977,7 +7977,7 @@ def plot_pf_coils(
         coils_z=coils_z,
         coils_dr=coils_dr,
         coils_dz=coils_dz,
-        dr_bore=dr_bore,
+        dr_cs_bore=dr_cs_bore,
         dr_cs=dr_cs,
         ohdz=dz_cs_full,
     )
@@ -9946,7 +9946,7 @@ def plot_cs_coil_structure(
     dr_cs_full = mfile.get("dr_cs_full", scan=scan)
     dz_cs_full = mfile.get("dz_cs_full", scan=scan)
     dz_cs = mfile.get("dz_cs_full", scan=scan)
-    dr_bore = mfile.get("dr_bore", scan=scan)
+    dr_cs_bore = mfile.get("dr_cs_bore", scan=scan)
     r_cs_current_filaments_array = [
         mfile.get(f"r_pf_cs_current_filaments{i}", scan=scan) for i in range(NFIXMX)
     ]
@@ -9956,7 +9956,7 @@ def plot_cs_coil_structure(
 
     # Plot the right side of the CS
     right_cs = patches.Rectangle(
-        (dr_bore, -dz_cs / 2),
+        (dr_cs_bore, -dz_cs / 2),
         dr_cs,
         dz_cs,
         edgecolor="black",
@@ -9967,8 +9967,8 @@ def plot_cs_coil_structure(
 
     # Plot the bore of the machine
     bore_rect = patches.Rectangle(
-        (-dr_bore, -dz_cs / 2),
-        dr_bore * 2,
+        (-dr_cs_bore, -dz_cs / 2),
+        dr_cs_bore * 2,
         dz_cs,
         edgecolor="black",
         facecolor="lightgrey",
@@ -9977,7 +9977,7 @@ def plot_cs_coil_structure(
     axis.add_patch(bore_rect)
 
     left_cs = patches.Rectangle(
-        (-dr_bore - dr_cs, -dz_cs / 2),
+        (-dr_cs_bore - dr_cs, -dz_cs / 2),
         dr_cs,
         dz_cs,
         edgecolor="black",
@@ -9995,9 +9995,9 @@ def plot_cs_coil_structure(
     if dr_cs_turn > 0:
         n_lines = int(dr_cs / dr_cs_turn)
         for i in range(1, n_lines):
-            x = dr_bore + i * dr_cs_turn
+            x = dr_cs_bore + i * dr_cs_turn
             axis.plot([x, x], [-dz_cs / 2, dz_cs / 2], **t_kwargs)
-            x_left = -dr_bore - dr_cs + i * dr_cs_turn
+            x_left = -dr_cs_bore - dr_cs + i * dr_cs_turn
             axis.plot([x_left, x_left], [-dz_cs / 2, dz_cs / 2], **t_kwargs)
     # Plot horizontal lines (along Z) for each turn
     if dz_cs_turn > 0:
@@ -10005,9 +10005,9 @@ def plot_cs_coil_structure(
         for j in range(1, n_hlines):
             y = -dz_cs / 2 + j * dz_cs_turn
             # Right CS
-            axis.plot([dr_bore, dr_bore + dr_cs], [y, y], **t_kwargs)
+            axis.plot([dr_cs_bore, dr_cs_bore + dr_cs], [y, y], **t_kwargs)
             # Left CS
-            axis.plot([-dr_bore - dr_cs, -dr_bore], [y, y], **t_kwargs)
+            axis.plot([-dr_cs_bore - dr_cs, -dr_cs_bore], [y, y], **t_kwargs)
 
         l_kwargs = {"color": "black", "linestyle": "--", "linewidth": 0.6, "alpha": 0.5}
 
@@ -10015,14 +10015,14 @@ def plot_cs_coil_structure(
         axis.axhline(y=0.0, **l_kwargs)
         # Plot a vertical line at x = 0.0
         axis.axvline(x=0.0, **l_kwargs)
-        # Plot a vertical line at x = dr_bore
-        axis.axvline(x=dr_bore, **l_kwargs)
-        # Plot a vertical line at x = -dr_bore
-        axis.axvline(x=-dr_bore, **l_kwargs)
-        # Plot a vertical line at x = dr_bore + dr_cs
-        axis.axvline(x=(dr_bore + dr_cs), **l_kwargs)
-        # Plot a vertical line at x = -dr_bore - dr_cs
-        axis.axvline(x=-(dr_bore + dr_cs), **l_kwargs)
+        # Plot a vertical line at x = dr_cs_bore
+        axis.axvline(x=dr_cs_bore, **l_kwargs)
+        # Plot a vertical line at x = -dr_cs_bore
+        axis.axvline(x=-dr_cs_bore, **l_kwargs)
+        # Plot a vertical line at x = dr_cs_bore + dr_cs
+        axis.axvline(x=(dr_cs_bore + dr_cs), **l_kwargs)
+        # Plot a vertical line at x = -dr_cs_bore - dr_cs
+        axis.axvline(x=-(dr_cs_bore + dr_cs), **l_kwargs)
         # Plot a vertical line at y= dz_cs / 2
         axis.axhline(y=(dz_cs / 2), **l_kwargs)
         # Plot a vertical line at y= -dz_cs / 2
diff --git a/process/data_structure/build_variables.py b/process/data_structure/build_variables.py
index 1ac5ef404d..c5fd2f0b98 100644
--- a/process/data_structure/build_variables.py
+++ b/process/data_structure/build_variables.py
@@ -106,7 +106,10 @@ class BuildData:
     """upper first wall thickness (m)"""
 
     dr_bore: float = 1.42
-    """central solenoid inboard radius (m) (`iteration variable 29`)"""
+    """Machine centre bore gap inboard radius (m) (`iteration variable 29`)"""
+
+    dr_cs_bore: float = 1.42
+    """Central solenoid bore radius [m]"""
 
     f_z_cryostat: float = 4.268
     """cryostat lid height scaling factor (tokamaks)"""
diff --git a/process/models/build.py b/process/models/build.py
index f7846ec457..3d7f49109c 100644
--- a/process/models/build.py
+++ b/process/models/build.py
@@ -1672,43 +1672,6 @@ def calculate_radial_build(self, output: bool):
                 self.data.build.dz_fw_plasma_gap,
             )
 
-        # Calculate pre-compression structure thickness
-        if (
-            CSPrecompressionConfiguration(self.data.build.i_cs_precomp)
-            == CSPrecompressionConfiguration.CS_PRECOMPRESSION_STRUCTURE_PRESENT
-            and self.data.build.i_tf_inside_cs == TFCSRadialConfiguration.TF_OUTSIDE_CS
-        ):
-            self.data.build.dr_cs_precomp = self.data.build.fseppc / (
-                2.0e0
-                * np.pi
-                * self.data.build.fcspc
-                * self.data.build.sigallpc
-                * (
-                    self.data.build.dr_bore
-                    + self.data.build.dr_bore
-                    + self.data.build.dr_cs
-                )
-            )
-        elif (
-            CSPrecompressionConfiguration(self.data.build.i_cs_precomp)
-            == CSPrecompressionConfiguration.CS_PRECOMPRESSION_STRUCTURE_PRESENT
-            and self.data.build.i_tf_inside_cs == TFCSRadialConfiguration.TF_INSIDE_CS
-        ):
-            self.data.build.dr_cs_precomp = self.data.build.fseppc / (
-                2.0e0
-                * np.pi
-                * self.data.build.fcspc
-                * self.data.build.sigallpc
-                * (
-                    2.0 * self.data.build.dr_bore
-                    + 2.0 * self.data.build.dr_tf_inboard
-                    + 2.0 * self.data.build.dr_cs_tf_gap
-                    + self.data.build.dr_cs
-                )
-            )
-        else:
-            self.data.build.dr_cs_precomp = 0.0e0
-
         # Issue #514 Radial dimensions of inboard leg
         # Calculate self.data.build.dr_tf_inboard if
         # self.data.tfcoil.dr_tf_wp_with_insulation is an iteration variable (140)
@@ -1720,14 +1683,34 @@ def calculate_radial_build(self, output: bool):
             )
 
         if self.data.build.i_tf_inside_cs == TFCSRadialConfiguration.TF_INSIDE_CS:
-            self.data.build.r_tf_inboard_in = (
+            self.data.build.r_tf_inboard_in = self.data.build.dr_bore
+            # CS bore radius [m]
+            self.data.build.dr_cs_bore = (
                 self.data.build.dr_bore
-                # NOTE: dr_bore is just the hollow space, the
-                # true dr_bore size used for flux calculations
-                # is dr_bore + dr_tf_inboard + dr_cs_tf_gap
+                + self.data.build.dr_tf_inboard
+                + self.data.build.dr_cs_tf_gap
             )
         else:
+            self.data.build.dr_cs_bore = self.data.build.dr_bore
+
+        # Calculate pre-compression structure thickness
+        if (
+            CSPrecompressionConfiguration(self.data.build.i_cs_precomp)
+            == CSPrecompressionConfiguration.CS_PRECOMPRESSION_STRUCTURE_PRESENT
+        ):
+            self.data.build.dr_cs_precomp = self.data.build.fseppc / (
+                2.0e0
+                * np.pi
+                * self.data.build.fcspc
+                * self.data.build.sigallpc
+                * (2.0 * self.data.build.dr_cs_bore + self.data.build.dr_cs)
+            )
+        else:
+            self.data.build.dr_cs_precomp = 0.0e0
+
+        if self.data.build.i_tf_inside_cs != TFCSRadialConfiguration.TF_INSIDE_CS:
             # Inboard side inner radius [m]
+            # This is not calculated above because it requires the dr_cs_precomp
             self.data.build.r_tf_inboard_in = (
                 self.data.build.dr_bore
                 + self.data.build.dr_cs
@@ -1916,7 +1899,7 @@ def calculate_radial_build(self, output: bool):
             + 0.5e0 * self.data.build.dr_tf_outboard
         )
 
-        # TF coil horizontal self.data.build.dr_bore [m]
+        # TF coil horizontal bore at mid-plane [m]
         self.data.build.dr_tf_inner_bore = (
             self.data.build.r_tf_outboard_mid - 0.5e0 * self.data.build.dr_tf_outboard
         ) - (self.data.build.r_tf_inboard_mid - 0.5e0 * self.data.build.dr_tf_inboard)
@@ -2050,21 +2033,6 @@ def calculate_radial_build(self, output: bool):
                 "OP ",
             )
 
-            if self.data.build.i_tf_inside_cs == TFCSRadialConfiguration.TF_INSIDE_CS:
-                po.ocmmnt(
-                    self.outfile,
-                    (
-                        "\n "
-                        "(The stated machine dr_bore size is just for the hollow space, "
-                    ),
-                )
-                po.ocmmnt(
-                    self.outfile,
-                    (
-                        "the true dr_bore size used for calculations is "
-                        "dr_bore + dr_tf_inboard + dr_cs_tf_gap)\n"
-                    ),
-                )
             if (
                 self.data.build.i_tf_inside_cs == TFCSRadialConfiguration.TF_INSIDE_CS
                 and self.data.tfcoil.i_tf_bucking >= 2
diff --git a/process/models/geometry/pfcoil.py b/process/models/geometry/pfcoil.py
index 1d6bf76a42..0af2e57506 100644
--- a/process/models/geometry/pfcoil.py
+++ b/process/models/geometry/pfcoil.py
@@ -13,7 +13,7 @@ def pfcoil_geometry(
     coils_z: list[float],
     coils_dr: list[float],
     coils_dz: list[float],
-    dr_bore: float,
+    dr_cs_bore: float,
     dr_cs: float,
     ohdz: float,
 ) -> tuple[np.ndarray, np.ndarray, RectangleGeometry]:
@@ -30,7 +30,7 @@ def pfcoil_geometry(
         list of pf coil radial thicknesses
     coils_dz:
         list of pf coil vertical thicknesses
-    dr_bore:
+    dr_cs_bore:
         central solenoid inboard radius
     dr_cs:
         central solenoid thickness
@@ -55,7 +55,7 @@ def pfcoil_geometry(
         z_points.append([z_1, z_2, z_2, z_1, z_1])
 
     central_coil = RectangleGeometry(
-        anchor_x=dr_bore, anchor_z=(-ohdz / 2), width=dr_cs, height=ohdz
+        anchor_x=dr_cs_bore, anchor_z=(-ohdz / 2), width=dr_cs, height=ohdz
     )
 
     return r_points, z_points, central_coil
diff --git a/process/models/pfcoil.py b/process/models/pfcoil.py
index fc0cd99df6..437951fcf8 100644
--- a/process/models/pfcoil.py
+++ b/process/models/pfcoil.py
@@ -182,7 +182,7 @@ def pfcoil(self):
             z_tf_inside_half=self.data.build.z_tf_inside_half,
             f_z_cs_tf_internal=self.data.pf_coil.f_z_cs_tf_internal,
             dr_cs=self.data.build.dr_cs,
-            dr_bore=self.data.build.dr_bore,
+            dr_cs_bore=self.data.build.dr_cs_bore,
         )
 
         self.data.pf_coil.z_cs_upper = self.data.pf_coil.z_pf_coil_upper[
@@ -649,9 +649,9 @@ def pfcoil(self):
                 * np.pi
                 * np.pi
                 * (
-                    (self.data.build.dr_bore * self.data.build.dr_bore)
+                    (self.data.build.dr_cs_bore * self.data.build.dr_cs_bore)
                     + (self.data.build.dr_cs * self.data.build.dr_cs) / 6.0e0
-                    + (self.data.build.dr_cs * self.data.build.dr_bore) / 2.0e0
+                    + (self.data.build.dr_cs * self.data.build.dr_cs_bore) / 2.0e0
                 )
                 / (self.data.pf_coil.dz_cs_full)
             )
@@ -1050,7 +1050,7 @@ def pfcoil(self):
                 c += 1
 
         self.data.pf_coil.itr_sum += (
-            (self.data.build.dr_bore + 0.5 * self.data.build.dr_cs)
+            (self.data.build.dr_cs_bore + 0.5 * self.data.build.dr_cs)
             * self.data.pf_coil.n_pf_coil_turns[self.data.pf_coil.n_cs_pf_coils - 1]
             * self.data.pf_coil.c_pf_coil_turn_peak_input[
                 self.data.pf_coil.n_cs_pf_coils - 1
@@ -1543,14 +1543,14 @@ def tf_pf_collision_detector(self):
                         if self.data.pf_coil.r_pf_coil_middle_group_array[
                             ii, ij
                         ] <= (  # Inboard TF coil collision
-                            self.data.build.dr_bore
+                            self.data.build.dr_cs_bore
                             + self.data.build.dr_cs
                             + self.data.build.dr_cs_precomp
                             + self.data.build.dr_cs_tf_gap
                             + self.data.build.dr_tf_inboard
                             + self.data.pf_coil.r_pf_coil_middle[i]
                         ) and self.data.pf_coil.r_pf_coil_middle_group_array[ii, ij] >= (
-                            self.data.build.dr_bore
+                            self.data.build.dr_cs_bore
                             + self.data.build.dr_cs
                             + self.data.build.dr_cs_precomp
                             + self.data.build.dr_cs_tf_gap
@@ -3009,7 +3009,7 @@ def calculate_cs_geometry(
         z_tf_inside_half: float,
         f_z_cs_tf_internal: float,
         dr_cs: float,
-        dr_bore: float,
+        dr_cs_bore: float,
     ) -> CSGeometry:
         """Calculate the geometry of the Central Solenoid (CS) coil.
 
@@ -3021,8 +3021,8 @@ def calculate_cs_geometry(
             Fractional height of CS relative to TF bore
         dr_cs : float
             Thickness of the CS coil (m)
-        dr_bore : float
-            Radius of the TF bore (m)
+        dr_cs_bore : float
+            Radius of the CS bore (m)
 
         Returns
         -------
@@ -3030,7 +3030,7 @@ def calculate_cs_geometry(
             Data class containing the geometry parameters of the CS coil
         """
         # Central Solenoid mean radius
-        r_cs_middle = dr_bore + (0.5e0 * dr_cs)
+        r_cs_middle = dr_cs_bore + (0.5e0 * dr_cs)
 
         # Scale the CS height relative to TF bore height
         z_cs_half = z_tf_inside_half * f_z_cs_tf_internal
@@ -3234,7 +3234,7 @@ def ohcalc(self):
             z_tf_inside_half=self.data.build.z_tf_inside_half,
             f_z_cs_tf_internal=self.data.pf_coil.f_z_cs_tf_internal,
             dr_cs=self.data.build.dr_cs,
-            dr_bore=self.data.build.dr_bore,
+            dr_cs_bore=self.data.build.dr_cs_bore,
         )
 
         self.data.pf_coil.z_cs_upper = self.data.pf_coil.z_pf_coil_upper[
@@ -3870,8 +3870,8 @@ def output_cs_structure(self) -> None:
         op.ovarre(
             self.outfile,
             "Radial thickness of the CS bore [m]",
-            "(dr_bore)",
-            self.data.build.dr_bore,
+            "(dr_cs_bore)",
+            self.data.build.dr_cs_bore,
             "OP ",
         )
         op.oblnkl(self.outfile)
diff --git a/tests/unit/models/test_pfcoil.py b/tests/unit/models/test_pfcoil.py
index 14e60ac74c..859f7b5608 100644
--- a/tests/unit/models/test_pfcoil.py
+++ b/tests/unit/models/test_pfcoil.py
@@ -2048,7 +2048,7 @@ def test_brookscoil(pfcoil):
 
 
 @pytest.mark.parametrize(
-    ("z_tf_inside_half", "f_z_cs_tf_internal", "dr_cs", "dr_bore", "expected"),
+    ("z_tf_inside_half", "f_z_cs_tf_internal", "dr_cs", "dr_cs_bore", "expected"),
     [
         # Typical values
         (
@@ -2101,13 +2101,13 @@ def test_brookscoil(pfcoil):
     ],
 )
 def test_calculate_cs_geometry(
-    cs_coil, z_tf_inside_half, f_z_cs_tf_internal, dr_cs, dr_bore, expected
+    cs_coil, z_tf_inside_half, f_z_cs_tf_internal, dr_cs, dr_cs_bore, expected
 ):
     result = cs_coil.calculate_cs_geometry(
         z_tf_inside_half=z_tf_inside_half,
         f_z_cs_tf_internal=f_z_cs_tf_internal,
         dr_cs=dr_cs,
-        dr_bore=dr_bore,
+        dr_cs_bore=dr_cs_bore,
     )
     for field in fields(result):
         assert pytest.approx(getattr(result, field.name)) == getattr(
@@ -2436,7 +2436,7 @@ def test_pfcoil(monkeypatch, pfcoil):
     monkeypatch.setattr(pfcoil.data.build, "dr_tf_outboard", 1.4)
     monkeypatch.setattr(pfcoil.data.build, "dr_tf_inboard", 1.4)
     monkeypatch.setattr(pfcoil.data.build, "r_tf_outboard_mid", 1.66e1)
-    monkeypatch.setattr(pfcoil.data.build, "dr_bore", 2.15)
+    monkeypatch.setattr(pfcoil.data.build, "dr_cs_bore", 2.15)
     monkeypatch.setattr(pfcoil.data.fwbs, "den_steel", 7.8e3)
     monkeypatch.setattr(pfcoil.data.pf_coil, "dr_pf_cs_middle_offset", 0.0)
     monkeypatch.setattr(pfcoil.data.pf_coil, "m_pf_coil_structure_total", 0.0)
@@ -2584,7 +2584,7 @@ def test_ohcalc(monkeypatch, reinitialise_error_module, cs_coil):
     monkeypatch.setattr(cs_coil.data.build, "z_tf_inside_half", 8.864)
     monkeypatch.setattr(cs_coil.data.build, "dr_cs", 6.510e-1)
     monkeypatch.setattr(cs_coil.data.fwbs, "den_steel", 7.8e3)
-    monkeypatch.setattr(cs_coil.data.build, "dr_bore", 2.6745)
+    monkeypatch.setattr(cs_coil.data.build, "dr_cs_bore", 2.6745)
     monkeypatch.setattr(cs_coil.data.pf_coil, "n_cs_pf_coils", 5)
     monkeypatch.setattr(cs_coil.data.pf_coil, "b_cs_peak_flat_top_end", 1.4e1)
     monkeypatch.setattr(cs_coil.data.pf_coil, "j_cs_flat_top_end", 1.693e7)