diff --git a/documentation/source/eng-models/central-solenoid.md b/documentation/source/eng-models/central-solenoid.md
index d489224950..e26e92a190 100644
--- a/documentation/source/eng-models/central-solenoid.md
+++ b/documentation/source/eng-models/central-solenoid.md
@@ -464,7 +464,7 @@ The critical current density *J*<sub>crit</sub> is a function of the temperature
 The temperature margin $\Delta$*T* is the difference between the current sharing temperature and the 
 operating temperature.  The current sharing temperature is the temperature at which *J*<sub>crit</sub> 
 is equal to the operating current density *J*<sub>op</sub>. The minimum allowed $\Delta$*T* can be 
-set using input parameter `tmargmin` together with constraint equation no. 60.
+set using input parameter `temp_cs_superconductor_margin_min` together with constraint equation no. 60.
 
 It is recommended that EITHER the temperature margin constraint (60), OR the current density 
 constraints (26 and 27) are activated.
diff --git a/documentation/source/eng-models/tf-coil-superconducting.md b/documentation/source/eng-models/tf-coil-superconducting.md
index aefd02bda4..e16dcd5a45 100644
--- a/documentation/source/eng-models/tf-coil-superconducting.md
+++ b/documentation/source/eng-models/tf-coil-superconducting.md
@@ -241,7 +241,7 @@ Three constraints are relevant to the operating current density $J_{\mbox{op}}$
 
 - Temperature margin (`constraint 36`) -- The critical current density $J_{\mbox{crit}}$ falls with 
   the temperature of the superconductor. The temperature margin $\Delta T$ is the difference between the current sharing temperature (at which $J_{\mbox{crit}}$ would be equal to $J_{\mbox{op}}$) and the operating temperature. The minimum allowed $\Delta T$
-can be set using `tmargmin` together with constraint equation 36. Note that if the temperature margin is positive, $J_{\mbox{op}}$ is guaranteed to be lower than \jcrit, and so constraints 33 and 36 need not both be turned on. It is recommended that only one of these two constraints is activated.  
+can be set using `temp_tf_superconductor_margin_min` together with constraint equation 36. Note that if the temperature margin is positive, $J_{\mbox{op}}$ is guaranteed to be lower than \jcrit, and so constraints 33 and 36 need not both be turned on. It is recommended that only one of these two constraints is activated.  
 
 ---------
 
diff --git a/examples/data/large_tokamak_IN.DAT b/examples/data/large_tokamak_IN.DAT
index cc19dd2588..fd176e85aa 100644
--- a/examples/data/large_tokamak_IN.DAT
+++ b/examples/data/large_tokamak_IN.DAT
@@ -91,7 +91,7 @@ icc = 35
 *--------------------------*
 icc = 36
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/examples/data/large_tokamak_eval_IN.DAT b/examples/data/large_tokamak_eval_IN.DAT
index 4d1db75a9f..d9b6e22249 100644
--- a/examples/data/large_tokamak_eval_IN.DAT
+++ b/examples/data/large_tokamak_eval_IN.DAT
@@ -383,7 +383,7 @@ dr_tf_wp_with_insulation = 0.5153787768966674 * radial thickness of winding pack
 dx_tf_turn_steel = 0.008012110032981922 * TF coil conduit case thickness (m) (`iteration variable 58`)
 dx_tf_wp_insulation   = 0.008 * Thickness of the ground insulation layer surrounding (m)
 temp_cs_superconductor_margin_min = 1.5 * minimum allowable temperature margin ; CS (K)
-tmargmin = 1.5 * minimum allowable temperature margin ; TFC AND CS (K)
+temp_tf_superconductor_margin_min = 1.5 * minimum allowable temperature margin ; TF (K)
 v_tf_coil_dump_quench_max_kv    = 10.0 * max voltage across TF coil during quench (kV) (`iteration variable 52`)
 f_a_tf_turn_cable_space_extra_void     = 0.3 * coolant fraction of TFC 'cable' (`i_tf_sup=1`); or of TFC leg (`i_tf_sup=0`)
 flu_tf_neutron_fast_max = 1e22 * max fluence in the TF coil
diff --git a/examples/data/large_tokamak_varied_min_net_electric_IN.DAT b/examples/data/large_tokamak_varied_min_net_electric_IN.DAT
index 432d68ae6e..954000e6c3 100644
--- a/examples/data/large_tokamak_varied_min_net_electric_IN.DAT
+++ b/examples/data/large_tokamak_varied_min_net_electric_IN.DAT
@@ -95,7 +95,7 @@ icc = 35
 *--------------------------*
 icc = 36
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/examples/data/large_tokamak_varyrun_IN.DAT b/examples/data/large_tokamak_varyrun_IN.DAT
index 75e2a2759f..d255af115b 100644
--- a/examples/data/large_tokamak_varyrun_IN.DAT
+++ b/examples/data/large_tokamak_varyrun_IN.DAT
@@ -96,7 +96,7 @@ icc = 35
 *--------------------------*
 icc = 36
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/examples/data/scan_example_file_IN.DAT b/examples/data/scan_example_file_IN.DAT
index 323c0321ca..325e75bb0e 100644
--- a/examples/data/scan_example_file_IN.DAT
+++ b/examples/data/scan_example_file_IN.DAT
@@ -102,7 +102,7 @@ icc = 35
 *--------------------------*
 icc = 36
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/process/core/data_structure/obsolete_vars.py b/process/core/data_structure/obsolete_vars.py
index fa3bb1c77f..b8a21ece37 100644
--- a/process/core/data_structure/obsolete_vars.py
+++ b/process/core/data_structure/obsolete_vars.py
@@ -483,6 +483,10 @@
     "temp_plasma_separatrix_kev": "temp_plasma_separatrix_electron_kev",
     "iohcl": "i_cs_use",
     "beta_total_vol_avg": None,
+    "tmargmin": [
+        "temp_tf_superconductor_margin_min",
+        "temp_cs_superconductor_margin_min",
+    ],
 }
 
 OBS_VARS_HELP = {
diff --git a/process/core/init.py b/process/core/init.py
index 4b5b537029..589cf67970 100644
--- a/process/core/init.py
+++ b/process/core/init.py
@@ -1218,27 +1218,6 @@ def check_process(inputs, data):  # noqa: ARG001
                 fsum=fsum,
             )
 
-    # Check that the temperature margins are not overdetermined
-    if data.tfcoil.tmargmin > 0.0001:
-        # This limit has been input and will be applied to both TFC and CS
-        if data.tfcoil.temp_tf_superconductor_margin_min > 0.0001:
-            logger.error(
-                "temp_tf_superconductor_margin_min and tmargmin should not both"
-                " be specified in IN.DAT"
-                " temp_tf_superconductor_margin_min has been ignored",
-                stacklevel=2,
-            )
-        if data.tfcoil.temp_cs_superconductor_margin_min > 0.0001:
-            logger.error(
-                "temp_cs_superconductor_margin_min and tmargmin should not both"
-                " be specified in IN.DAT"
-                " temp_cs_superconductor_margin_min has been ignored",
-                stacklevel=2,
-            )
-
-        data.tfcoil.temp_tf_superconductor_margin_min = data.tfcoil.tmargmin
-        data.tfcoil.temp_cs_superconductor_margin_min = data.tfcoil.tmargmin
-
     if (
         data.physics.tauee_in > 1e-10
         and data.physics.i_confinement_time != ConfinementTimeModel.NSTX_GYRO_BOHM
diff --git a/process/core/input.py b/process/core/input.py
index c288a0fc58..8af3564ff3 100644
--- a/process/core/input.py
+++ b/process/core/input.py
@@ -849,7 +849,6 @@ def bounds(self) -> tuple[NumberType | None, NumberType | None]:
     "dx_tf_wp_insulation": InputVariable("tfcoil", float, range=(0.0, 0.1)),
     "life_plant": InputVariable("costs", float, range=(1.0, 100.0)),
     "tmain": InputVariable("costs", float, range=(0.0, 100.0)),
-    "tmargmin": InputVariable("tfcoil", float, range=(0.0, 20.0)),
     "temp_cs_superconductor_margin_min": InputVariable(
         "tfcoil", float, range=(0.0, 20.0)
     ),
diff --git a/process/core/io/plot/summary/reporting/constraints.py b/process/core/io/plot/summary/reporting/constraints.py
index 0d70177b13..dad262bc15 100644
--- a/process/core/io/plot/summary/reporting/constraints.py
+++ b/process/core/io/plot/summary/reporting/constraints.py
@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import re
 from typing import TYPE_CHECKING
 
 import numpy as np
@@ -15,6 +16,35 @@
 __all__ = ["plot_equality_constraint_equations", "plot_inequality_constraint_equations"]
 
 
+def _var_label_formatting(var_label: str) -> str:
+    """Format normalised-residue variable labels for display.
+
+    If ``var_label`` is a string ending with ``"_normalised_residue"``, the
+    suffix is removed, trailing underscores are stripped, and remaining
+    underscores are replaced with spaces. Underscores appearing within LaTeX
+    expressions delimited by ``$...$`` or ``$$...$$`` are preserved.
+
+    Parameters
+    ----------
+    var_label : str
+        Variable label to format. Non-string values, or strings that do not end
+        with ``"_normalised_residue"``, are returned unchanged.
+
+    Returns
+    -------
+    str
+        The formatted label if applicable, otherwise the original input value.
+    """
+    if isinstance(var_label, str) and var_label.endswith("_normalised_residue"):
+        var_label = var_label.removesuffix("_normalised_residue").rstrip("_")
+        parts = re.split(r"(\$\$.*?\$\$|\$[^$]*\$)", var_label)
+        var_label = "".join(
+            part.replace("_", " ") if i % 2 == 0 else part
+            for i, part in enumerate(parts)
+        )
+    return var_label
+
+
 def plot_equality_constraint_equations(axis: plt.Axes, m_file_data: MFile, scan: int):
     """Plot the equality constraints for a solution and their normalised residuals
 
@@ -45,6 +75,7 @@ def plot_equality_constraint_equations(axis: plt.Axes, m_file_data: MFile, scan:
 
         # Use the variable name if available, else fallback to "eq_conXXX"
         var_label = con_names.get(n, f"eq_con{n:03d}")
+        var_label = _var_label_formatting(var_label)
 
         # Normalized residual of the constraint
         con_norm_residual = m_file_data.data[f"eq_con{n:03d}"].get_scan(scan)
@@ -53,14 +84,6 @@ def plot_equality_constraint_equations(axis: plt.Axes, m_file_data: MFile, scan:
         con_units_raw = m_file_data.data[f"eq_units_con{n:03d}"].get_scan(scan)
         con_units = str(con_units_raw).strip("'`")
 
-        # Remove '_normalised_residue' from the label if present
-        if isinstance(var_label, str) and var_label.endswith("_normalised_residue"):
-            var_label = var_label.replace("_normalised_residue", "")
-
-            # Remove trailing underscores and replace underscores between words with
-            # spaces
-            var_label = var_label.rstrip("_").replace("_", " ")
-
         # Plot the normalised residual as a bar
         axis.barh(
             n_plot,
@@ -143,6 +166,7 @@ def plot_inequality_constraint_equations(axis: plt.Axes, m_file: MFile, scan: in
 
         # Use the variable name if available, else fallback to "ineq_conXXX"
         var_label = con_names.get(n, f"ineq_con{n:03d}")
+        var_label = _var_label_formatting(var_label)
 
         # Normalized residual of the constraint
         con_residual_norm = m_file.data[f"ineq_con{n:03d}"].get_scan(scan)
@@ -167,11 +191,6 @@ def plot_inequality_constraint_equations(axis: plt.Axes, m_file: MFile, scan: in
             zorder=0,
         )
 
-        # Remove '_normalised_residue' from the label if present
-        if isinstance(var_label, str) and var_label.endswith("_normalised_residue"):
-            var_label = var_label.replace("_normalised_residue", "")
-            var_label = var_label.rstrip("_").replace("_", " ")
-
         # Calculate the normalised constraint threshold depending if the constraint is an
         # upper
         # or lower limit
diff --git a/process/core/solver/constraints.py b/process/core/solver/constraints.py
index d8013775bf..486b207df0 100644
--- a/process/core/solver/constraints.py
+++ b/process/core/solver/constraints.py
@@ -997,18 +997,19 @@ def constraint_equation_35(constraint_registration, data):
     )
 
 
-@ConstraintManager.register_constraint(36, "K", ">=")
+@ConstraintManager.register_constraint(36, "A/m²", "<=")
 def constraint_equation_36(constraint_registration, data):
     """Equation for TF coil s/c temperature margin lower limit (SCTF)
+    by means of the actual to critical current density
 
-    temp_tf_superconductor_margin:
-        TF coil temperature margin (K)
-    temp_tf_superconductor_margin_min:
-        minimum allowable temperature margin : TF coils (K)
+    j_tf_wp:
+        winding pack current density (A/m²)
+    j_tf_wp_temp_margin:
+        superconducting strand critical current density (A/m²)
     """
-    return geq(
-        data.tfcoil.temp_tf_superconductor_margin,
-        data.tfcoil.temp_tf_superconductor_margin_min,
+    return leq(
+        data.tfcoil.j_tf_wp,
+        data.tfcoil.j_tf_wp_temp_margin,
         constraint_registration,
     )
 
diff --git a/process/data_structure/numerics.py b/process/data_structure/numerics.py
index b34af3cf6b..700320f4ab 100644
--- a/process/data_structure/numerics.py
+++ b/process/data_structure/numerics.py
@@ -232,10 +232,10 @@ class NumericsData:
             "Plasma injected power (Pₐᵤₓ) upper limit      ",
             "TF coil case stress upper limit  ",
             "TF coil conduit stress upper limit ",
-            "TF coil superconductor critical current density upper limit  ",
+            r"TF coil superconductor $j_{\mathrm{crit}}$ upper limit (ratio) ",
             "TF quench dump voltage upper limit         ",
             "TF quench hotspot current density upper limit         ",
-            "TF coil superconductor temperature margin lower limit ",
+            r"TF coil superconductor $j_{\mathrm{crit}}$ upper limit (T margin) ",
             "HCD normalised current drive efficiency (γ) upper limit        ",  # noqa: RUF001
             "FW coolant temperature rise upper limit ",
             "FW peak temperature limit",
@@ -335,7 +335,8 @@ class NumericsData:
     * (33) I_op / I_critical (TF coil) (SCTF) (itv 50,56,57,58,59,60,24)
     * (34) Dump voltage upper limit (SCTF) (itv 51,52,56,57,58,59,60,24)
     * (35) TF Quench Hotspot J limit (SCTF) (itv 53,56,57,58,59,60,24)
-    * (36) TF coil temperature margin lower limit (SCTF) (itv 54,55,56,57,58,59,60,24)
+    * (36) TF coil superconductor critical current density upper limit (T margin) (SCTF)
+    (itv 54,55,56,57,58,59,60,24)
     * (37) Current drive gamma upper limit (itv 40,47)
     * (38) First wall coolant temperature rise upper limit (itv 62)
     * (39) First wall peak temperature upper limit (itv 63)
diff --git a/process/data_structure/tfcoil_variables.py b/process/data_structure/tfcoil_variables.py
index 1e9bdb5a55..a81016dbc0 100644
--- a/process/data_structure/tfcoil_variables.py
+++ b/process/data_structure/tfcoil_variables.py
@@ -337,13 +337,16 @@ class TFData:
     """
 
     j_tf_bus: float = 1.25e6
-    """bussing current density (A/m2)"""
+    """bussing current density (A/m²)"""
 
     j_crit_str_tf: float = 0.0
     """j_crit_str : superconductor strand critical current density under operating
-    conditions (A/m2). Necessary for the cost calculation in $/kAm
+    conditions (A/m²).
     """
 
+    j_tf_wp_temp_margin: float = 0.0
+    """j_tf_wp_temp_margin : allowable TF coil winding pack current density, for specified temperature margin (A/m²)"""
+
     j_crit_str_0: list[float] = field(
         default_factory=lambda: np.array([
             596905475.80390120,
@@ -357,18 +360,18 @@ class TFData:
             865652122.9071957,
         ])
     )
-    """j_crit_str_pf_0 : superconductor strand critical current density at 6 T and 4.2 K (A/m2)
+    """j_crit_str_pf_0 : superconductor strand critical current density at 6 T and 4.2 K (A/m²)
     Necessary for the cost calculation in $/kAm
     """
 
     j_tf_wp_critical: float = 0.0
-    """critical current density for winding pack (A/m2)"""
+    """critical current density for winding pack (A/m²)"""
 
     j_tf_wp_quench_heat_max: float = 0.0
-    """allowable TF coil winding pack current density, for dump temperature rise protection (A/m2)"""
+    """allowable TF coil winding pack current density, for dump temperature rise protection (A/m²)"""
 
     j_tf_wp: float = 0.0
-    """winding pack engineering current density (A/m2)"""
+    """winding pack engineering current density (A/m²)"""
 
     j_tf_coil_full_area: float = 0.0
     """Inboard leg mid-plane full coil area current density (A/m²)
@@ -670,12 +673,6 @@ class TFData:
     temp_cs_superconductor_margin_min: float = 0.0
     """minimum allowable temperature margin : CS (K)"""
 
-    tmargmin: float = 0.0
-    """minimum allowable temperature margin : TFC AND CS (K)"""
-
-    temp_margin: float = 0.0
-    """temperature margin (K)"""
-
     temp_tf_superconductor_margin: float = 0.0
     """TF coil superconductor temperature margin (K)"""
 
diff --git a/process/models/availability.py b/process/models/availability.py
index f2014bd22a..e167943abf 100644
--- a/process/models/availability.py
+++ b/process/models/availability.py
@@ -737,7 +737,7 @@ def calc_u_unplanned_magnets(self, output: bool) -> float:
         This routine calculates the unplanned unavailability of the magnets,
         using the methodology outlined in the 2014 EUROfusion
         RAMI report.
-        2014 EUROfusion RAMI report, &quot;Availability in PROCESS&quot;
+        2014 EUROfusion RAMI report, "Availability in PROCESS";
 
         Parameters
         ----------
@@ -750,12 +750,11 @@ def calc_u_unplanned_magnets(self, output: bool) -> float:
             unplanned unavailability of magnets
         """
         # Magnet temperature margin limit (K)
-        # Use the lower of the two values.  Issue #526
+        # Use the lower of the two values.  Issue #527
         tmargmin = min(
             self.data.tfcoil.temp_tf_superconductor_margin_min,
             self.data.tfcoil.temp_cs_superconductor_margin_min,
         )
-        mag_temp_marg_limit = tmargmin
 
         # Magnet maintenance time (years)
         mag_main_time = 0.5e0
@@ -768,11 +767,11 @@ def calc_u_unplanned_magnets(self, output: bool) -> float:
         # Point at which risk of unplanned unavailability increases
         # conf_mag is the c factor, which determines the temperature margin at which
         # lifetime starts to decline.
-        start_of_risk = mag_temp_marg_limit / self.data.costs.conf_mag
+        start_of_risk = tmargmin / self.data.costs.conf_mag
 
         # Determine if temperature margin is in region with risk of
         # unplanned unavailability
-        if self.data.tfcoil.temp_margin >= start_of_risk:
+        if self.data.tfcoil.temp_tf_superconductor_margin >= start_of_risk:
             u_unplanned_magnets = mag_min_u_unplanned
         else:
             # Linear decrease in expected lifetime when approaching the limit
@@ -782,7 +781,7 @@ def calc_u_unplanned_magnets(self, output: bool) -> float:
                     self.data.costs.t_plant_operational_total_yrs
                     / (start_of_risk - tmargmin)
                 )
-                * (self.data.tfcoil.temp_margin - tmargmin),
+                * (self.data.tfcoil.temp_tf_superconductor_margin - tmargmin),
             )
             u_unplanned_magnets = mag_main_time / (t_life + mag_main_time)
 
@@ -792,7 +791,7 @@ def calc_u_unplanned_magnets(self, output: bool) -> float:
         if output:
             po.ocmmnt(self.outfile, "Magnets:")
             po.oblnkl(self.outfile)
-            po.ovarre(
+            po.ovarre(  # This is of questionable interest...
                 self.outfile, "Minimum temperature margin (K)", "(tmargmin)", tmargmin
             )
             po.ovarre(
@@ -804,8 +803,8 @@ def calc_u_unplanned_magnets(self, output: bool) -> float:
             po.ovarre(
                 self.outfile,
                 "Temperature Margin (K)",
-                "(temp_margin)",
-                self.data.tfcoil.temp_margin,
+                "(temp_tf_superconductor_margin_min)",
+                self.data.tfcoil.temp_tf_superconductor_margin,
                 "OP ",
             )
             po.ovarre(
diff --git a/process/models/stellarator/coils/calculate.py b/process/models/stellarator/coils/calculate.py
index 151e34abc5..f6010ed8eb 100644
--- a/process/models/stellarator/coils/calculate.py
+++ b/process/models/stellarator/coils/calculate.py
@@ -417,7 +417,7 @@ def winding_pack_total_size(
         # jcrit for this bmax:
         jcrit_vector[k] = jcrit_from_material(
             b_max_k[k],
-            data.tfcoil.tftmp + data.tfcoil.tmargmin,
+            data.tfcoil.tftmp + data.tfcoil.temp_tf_superconductor_margin_min,
             data.tfcoil.i_tf_sc_mat,
             data.tfcoil.bcritsc,
             data.tfcoil.f_a_tf_turn_cable_copper,
@@ -425,7 +425,7 @@ def winding_pack_total_size(
             data.tfcoil.tcritsc,
             data.tfcoil.f_a_tf_turn_cable_space_extra_void,
             data.tfcoil.j_tf_wp,
-        )  # Get here a temperature margin from data.tfcoil.tmargtf.
+        )
 
     # The operation current density weighted with the global iop/icrit fraction
     lhs[:] = data.constraints.f_j_tf_wp_critical_max * jcrit_vector
diff --git a/process/models/superconductors.py b/process/models/superconductors.py
index ff435bdd8a..dd83dfc641 100644
--- a/process/models/superconductors.py
+++ b/process/models/superconductors.py
@@ -6,7 +6,6 @@
 from types import DynamicClassAttribute
 
 import numpy as np
-from scipy import optimize
 
 from process.core.exceptions import ProcessValueError
 
@@ -298,50 +297,6 @@ def jcrit_rebco(
     return j_critical, validity, b_c20_max, temp_c0_max
 
 
-def current_sharing_rebco(bfield, j):
-    """Current sharing temperature for "REBCO" 2nd generation HTS superconductor
-
-    Parameters
-    ----------
-    bfield :
-        Magnetic field at superconductor (T)
-    j :
-        Current density in superconductor (A/m2)
-
-    Returns
-    -------
-    current_sharing_t :
-        Current sharing temperature (K)
-    """
-
-    def deltaj_rebco(temperature):
-        jcritical, _, _, _ = jcrit_rebco(
-            temp_conductor=temperature,
-            b_conductor=bfield,
-            temp_c0_max=SuperconductorModel.CROCO_REBCO.temp_crit_zero_field_strain,
-            b_c20_max=SuperconductorModel.CROCO_REBCO.b_crit_zero_field_strain,
-        )
-        return jcritical - j
-
-    # No additional arguments are required for deltaj_rebco since it only has one
-    # argument.
-
-    estimate = 10.0
-    another_estimate = 20.0
-    current_sharing_t, _root_result = optimize.newton(
-        deltaj_rebco,
-        estimate,
-        tol=1e-6,
-        rtol=1e-6,
-        maxiter=50,
-        x1=another_estimate,
-        full_output=True,
-        disp=True,
-    )
-
-    return current_sharing_t
-
-
 def itersc(
     temp_conductor: float,
     b_conductor: float,
diff --git a/process/models/tfcoil/superconducting.py b/process/models/tfcoil/superconducting.py
index 34fcfa3d97..122aeadffa 100644
--- a/process/models/tfcoil/superconducting.py
+++ b/process/models/tfcoil/superconducting.py
@@ -14,6 +14,7 @@
 from process.core.exceptions import ProcessValueError
 from process.data_structure.superconducting_tf_coil_variables import TFWPIntegerTurnType
 from process.models import superconductors
+from process.models.availability import AvailabilityModel
 from process.models.superconductors import (
     N_CROCO_STRANDS_TURN,
     SuperconductorMaterial,
@@ -942,6 +943,28 @@ def output_tf_superconductor_info(self):
         """Output TF superconductor information"""
         d_sc_tf = self.data.superconducting_tfcoil
 
+        if self.data.tfcoil.i_str_wp == 0:
+            strain = self.data.tfcoil.str_tf_con_res
+        else:
+            strain = self.data.tfcoil.str_wp
+
+        try:
+            temp_margin = self.calculate_superconductor_temperature_margin(
+                i_tf_superconductor=self.data.tfcoil.i_tf_sc_mat,
+                j_superconductor=d_sc_tf.j_tf_superconductor,
+                b_tf_inboard_peak=self.data.tfcoil.b_tf_inboard_peak_with_ripple,
+                strain=strain,
+                bc20m=d_sc_tf.b_tf_superconductor_critical_zero_temp_strain,
+                tc0m=d_sc_tf.temp_tf_superconductor_critical_zero_field_strain,
+                c0=1.0e10,
+                temp_tf_coolant_peak_field=self.data.tfcoil.tftmp,
+                data=self.data,
+            )
+        except ProcessValueError:
+            # Non-positive or failed optimisation / j_crit calculation
+            temp_margin = np.nan
+
+        self.data.tfcoil.temp_tf_superconductor_margin = temp_margin
         po.oheadr(self.outfile, "TF Coils Superconductor Information")
         po.ovarre(
             self.outfile,
@@ -1174,144 +1197,6 @@ def output_tf_superconductor_info(self):
             "OP ",
         )
 
-    @staticmethod
-    def calculate_superconductor_temperature_margin(
-        i_tf_superconductor: int,
-        j_superconductor: float,
-        b_tf_inboard_peak: float,
-        strain: float,
-        bc20m: float,
-        tc0m: float,
-        c0: float,
-        temp_tf_coolant_peak_field: float,
-        data: DataStructure,
-    ):
-        """Calculate the temperature margin of the TF superconductor.
-
-        Parameters
-        ----------
-        i_tf_superconductor:
-            Switch for conductor type:
-            - 1: ITER Nb3Sn, standard parameters
-            - 2: Bi-2212 High Temperature Superconductor
-            - 3: NbTi
-            - 4: ITER Nb3Sn, user-defined parameters
-            - 5: WST Nb3Sn parameterisation
-            - 7: Durham Ginzburg-Landau Nb-Ti parameterisation
-            - 8: Durham Ginzburg-Landau critical surface model for REBCO
-            - 9: Hazelton experimental data + Zhai conceptual model for REBCO
-        j_superconductor:
-            Current density in superconductor (A/m²).
-        b_tf_inboard_peak:
-            Peak field at conductor (T).
-        strain:
-            Strain on superconductor.
-        bc20m:
-            Critical field at zero temperature and strain (T).
-        tc0m:
-            Critical temperature at zero field and strain (K).
-        c0:
-            Constant used in NbTi critical current density calculation (A/m²).
-        temp_tf_coolant_peak_field:
-            He temperature at peak field point (K).
-
-        Returns
-        -------
-        type
-            temp_tf_superconductor_margin.
-
-
-        Raises
-        ------
-        ProcessValueError
-            If an unknown superconductor type is specified.
-        """
-        # =================================================================
-        # Calculate temperature margin of superconductor
-
-        #  Temperature margin (already calculated in superconductors.bi2212 for
-        # i_tf_superconductor=2)
-        match SuperconductorModel(i_tf_superconductor):
-            case SuperconductorModel.BI2212:
-                # Bi-2212: temperature margin already calculated elsewhere
-                temp_tf_superconductor_margin = 0.0
-                # Find temperature at which current density margin = 0
-            case (
-                SuperconductorModel.ITER_NB3SN
-                | SuperconductorModel.OLD_LUBELL_NBTI
-                | SuperconductorModel.USER_DEFINED_NB3SN
-                | SuperconductorModel.WST_NB3SN
-                | SuperconductorModel.DURHAM_NBTI
-                | SuperconductorModel.DURHAM_REBCO
-                | SuperconductorModel.HAZELTON_ZHAI_REBCO
-            ):
-                if (
-                    SuperconductorModel(i_tf_superconductor)
-                    == SuperconductorModel.OLD_LUBELL_NBTI
-                ):
-                    arguments = (
-                        i_tf_superconductor,
-                        j_superconductor,
-                        b_tf_inboard_peak,
-                        strain,
-                        bc20m,
-                        tc0m,
-                        data.superconducting_tfcoil.dr_tf_hts_tape,
-                        data.superconducting_tfcoil.dx_tf_hts_tape_rebco,
-                        data.superconducting_tfcoil.dx_tf_hts_tape_total,
-                        c0,
-                    )
-                else:
-                    arguments = (
-                        i_tf_superconductor,
-                        j_superconductor,
-                        b_tf_inboard_peak,
-                        strain,
-                        bc20m,
-                        tc0m,
-                        data.superconducting_tfcoil.dr_tf_hts_tape,
-                        data.superconducting_tfcoil.dx_tf_hts_tape_rebco,
-                        data.superconducting_tfcoil.dx_tf_hts_tape_total,
-                    )
-
-                another_estimate = 2 * temp_tf_coolant_peak_field
-                (
-                    t_zero_margin,
-                    _,
-                ) = optimize.newton(
-                    superconductors.superconductor_current_density_margin,
-                    temp_tf_coolant_peak_field,
-                    fprime=None,
-                    args=arguments,
-                    tol=1.0e-06,
-                    maxiter=50,
-                    fprime2=None,
-                    x1=another_estimate,
-                    rtol=1.0e-6,
-                    full_output=True,
-                    disp=True,
-                )
-                temp_tf_superconductor_margin = (
-                    t_zero_margin - temp_tf_coolant_peak_field
-                )
-                data.tfcoil.temp_margin = temp_tf_superconductor_margin
-
-                if temp_tf_superconductor_margin <= 0.0e0:
-                    logger.error(
-                        f"""Negative TFC temperature margin
-                    temp_tf_superconductor_margin: {temp_tf_superconductor_margin}
-                    b_tf_inboard_peak: {b_tf_inboard_peak}
-                    j_superconductor: {j_superconductor}
-                    """
-                    )
-            case _:
-                raise ProcessValueError(
-                    f"Unknown superconductor type: "
-                    f"i_tf_superconductor={i_tf_superconductor}"
-                )
-
-        return temp_tf_superconductor_margin
-
     @staticmethod
     def quench_heat_protection_current_density(
         c_tf_turn: float,
@@ -2268,6 +2153,148 @@ def run_and_output_stress(self) -> None:
                 self.data.tfcoil.sig_tf_case = 0.0e0
                 self.data.tfcoil.sig_tf_wp = 0.0e0
 
+    @staticmethod
+    def calculate_superconductor_temperature_margin(
+        i_tf_superconductor: int,
+        j_superconductor: float,
+        b_tf_inboard_peak: float,
+        strain: float,
+        bc20m: float,
+        tc0m: float,
+        c0: float,
+        temp_tf_coolant_peak_field: float,
+        data: DataStructure,
+    ) -> float:
+        """Calculate the temperature margin of the TF superconductor.
+
+        Parameters
+        ----------
+        i_tf_superconductor:
+            Switch for conductor type:
+            - 1: ITER Nb3Sn, standard parameters
+            - 2: Bi-2212 High Temperature Superconductor
+            - 3: NbTi
+            - 4: ITER Nb3Sn, user-defined parameters
+            - 5: WST Nb3Sn parameterisation
+            - 7: Durham Ginzburg-Landau Nb-Ti parameterisation
+            - 8: Durham Ginzburg-Landau critical surface model for REBCO
+            - 9: Hazelton experimental data + Zhai conceptual model for REBCO
+        j_superconductor:
+            Current density in superconductor (A/m²).
+        b_tf_inboard_peak:
+            Peak field at conductor (T).
+        strain:
+            Strain on superconductor.
+        bc20m:
+            Critical field at zero temperature and strain (T).
+        tc0m:
+            Critical temperature at zero field and strain (K).
+        c0:
+            Constant used in NbTi critical current density calculation (A/m²).
+        temp_tf_coolant_peak_field:
+            He temperature at peak field point (K).
+
+        Returns
+        -------
+        type
+            temp_tf_superconductor_margin.
+
+
+        Raises
+        ------
+        ProcessValueError
+            If an unknown superconductor type is specified.
+        """
+        model = SuperconductorModel(i_tf_superconductor)
+
+        args = (
+            i_tf_superconductor,
+            j_superconductor,
+            b_tf_inboard_peak,
+            strain,
+            bc20m,
+            tc0m,
+            data.superconducting_tfcoil.dr_tf_hts_tape,
+            data.superconducting_tfcoil.dx_tf_hts_tape_rebco,
+            data.superconducting_tfcoil.dx_tf_hts_tape_total,
+        )
+
+        match model:
+            case SuperconductorModel.BI2212:
+                return 0.0
+
+            case SuperconductorModel.OLD_LUBELL_NBTI:
+                args += (c0,)
+
+            case (
+                SuperconductorModel.ITER_NB3SN
+                | SuperconductorModel.USER_DEFINED_NB3SN
+                | SuperconductorModel.WST_NB3SN
+                | SuperconductorModel.DURHAM_NBTI
+                | SuperconductorModel.DURHAM_REBCO
+                | SuperconductorModel.HAZELTON_ZHAI_REBCO
+            ):
+                pass
+
+            case _:
+                raise ProcessValueError(
+                    f"Unknown superconductor type: "
+                    f"i_tf_superconductor={i_tf_superconductor}"
+                )
+
+        j_scale = 1.0 / max(abs(j_superconductor), 1.0)
+
+        result = optimize.least_squares(
+            lambda t: (
+                j_scale
+                * superconductors.superconductor_current_density_margin(t[0], *args)
+            ),
+            x0=[temp_tf_coolant_peak_field],
+            bounds=([1e-3], [0.999 * tc0m]),
+            method="trf",
+            xtol=1e-11,
+            ftol=None,
+            gtol=None,
+            max_nfev=50,
+        )
+
+        if not result.success:
+            txt = f"Error in TF temperature margin calculation: {result.message}"
+            logger.error(txt)
+            raise ProcessValueError(txt)
+
+        normalised_residual = float(result.fun[0])
+        residual_tol = 1e-10
+
+        if (
+            not np.isfinite(normalised_residual)
+            or abs(normalised_residual) > residual_tol
+        ):
+            txt = (
+                "Superconductor current density residual for temperature margin "
+                "calculation is not sufficiently close to zero: "
+                f"{normalised_residual:.6g} "
+                f"(normalised tolerance: {residual_tol:.6g})"
+            )
+
+            logger.error(txt)
+            raise ProcessValueError(txt)
+
+        t_zero_margin = float(result.x[0])
+
+        margin = t_zero_margin - temp_tf_coolant_peak_field
+
+        if margin <= 0:
+            logger.error(
+                "Non-positive TFC temperature margin: %s; "
+                "peak field: %s; superconductor current density: %s",
+                margin,
+                b_tf_inboard_peak,
+                j_superconductor,
+            )
+
+        return margin
+
 
 @dataclass(slots=True)
 class TFGeneralTurnGeometry:
@@ -2353,7 +2380,7 @@ class CICCSuperconductingTFCoil(SuperconductingTFCoil):
     """Cable in Conduit Superconducting TF Coil class."""
 
     def run(self, output: bool = False):
-        """Run the superconducting TF coil model for a CroCo conductor with REBCO tape.
+        """Run the superconducting TF coil model for a CICC conductor.
 
         Parameters
         ----------
@@ -2708,6 +2735,29 @@ def run(self, output: bool = False):
             * self.data.tfcoil.n_tf_coil_turns
         )
 
+        # Calculate allowable current density at T = T_peak + T_margin_min
+        margin_superconductor_info = self.tf_cable_in_conduit_superconductor_properties(
+            a_tf_turn_cable_space=self.data.tfcoil.a_tf_turn_cable_space_no_void,
+            a_tf_turn=self.data.tfcoil.a_tf_turn,
+            a_tf_turn_cable_space_effective=d_sc_tf.a_tf_turn_cable_space_effective,
+            f_a_tf_turn_cable_space_cooling=d_sc_tf.f_a_tf_turn_cable_space_cooling,
+            b_tf_inboard_peak=self.data.tfcoil.b_tf_inboard_peak_with_ripple,
+            f_a_tf_turn_cable_copper=self.data.tfcoil.f_a_tf_turn_cable_copper,
+            c_tf_turn=self.data.tfcoil.c_tf_turn,
+            j_tf_wp=self.data.tfcoil.j_tf_wp,
+            i_tf_superconductor=self.data.tfcoil.i_tf_sc_mat,
+            f_strain_scale=self.data.tfcoil.fhts,
+            temp_tf_coolant_peak_field=self.data.tfcoil.tftmp
+            + self.data.tfcoil.temp_tf_superconductor_margin_min,
+            bcritsc=self.data.tfcoil.bcritsc,
+            tcritsc=self.data.tfcoil.tcritsc,
+            data=self.data,
+        )
+        self.data.tfcoil.j_tf_wp_temp_margin = (
+            margin_superconductor_info.j_tf_wp_critical
+        )
+
+        # Calculate critical current density at T = T_peak
         critical_superconductor_info = (
             self.tf_cable_in_conduit_superconductor_properties(
                 a_tf_turn_cable_space=self.data.tfcoil.a_tf_turn_cable_space_no_void,
@@ -2728,6 +2778,7 @@ def run(self, output: bool = False):
         )
 
         self.data.tfcoil.j_tf_wp_critical = critical_superconductor_info.j_tf_wp_critical
+
         d_sc_tf.j_tf_superconductor_critical = (
             critical_superconductor_info.j_superconductor_critical
         )
@@ -2746,24 +2797,29 @@ def run(self, output: bool = False):
             critical_superconductor_info.c_turn_cables_critical
         )
 
-        if self.data.tfcoil.i_str_wp == 0:
-            strain = self.data.tfcoil.str_tf_con_res
-        else:
-            strain = self.data.tfcoil.str_wp
+        match AvailabilityModel(self.data.costs.i_plant_availability):
+            # Only calculate temperature margin if required
+            case AvailabilityModel.MORRIS | AvailabilityModel.ST:
+                if self.data.tfcoil.i_str_wp == 0:
+                    strain = self.data.tfcoil.str_tf_con_res
+                else:
+                    strain = self.data.tfcoil.str_wp
 
-        self.data.tfcoil.temp_tf_superconductor_margin = (
-            self.calculate_superconductor_temperature_margin(
-                i_tf_superconductor=self.data.tfcoil.i_tf_sc_mat,
-                j_superconductor=d_sc_tf.j_tf_superconductor,
-                b_tf_inboard_peak=self.data.tfcoil.b_tf_inboard_peak_with_ripple,
-                strain=strain,
-                bc20m=d_sc_tf.b_tf_superconductor_critical_zero_temp_strain,
-                tc0m=d_sc_tf.temp_tf_superconductor_critical_zero_field_strain,
-                c0=1.0e10,
-                temp_tf_coolant_peak_field=self.data.tfcoil.tftmp,
-                data=self.data,
-            )
-        )
+                temp_margin = self.calculate_superconductor_temperature_margin(
+                    i_tf_superconductor=self.data.tfcoil.i_tf_sc_mat,
+                    j_superconductor=d_sc_tf.j_tf_superconductor,
+                    b_tf_inboard_peak=self.data.tfcoil.b_tf_inboard_peak_with_ripple,
+                    strain=strain,
+                    bc20m=d_sc_tf.b_tf_superconductor_critical_zero_temp_strain,
+                    tc0m=d_sc_tf.temp_tf_superconductor_critical_zero_field_strain,
+                    c0=1.0e10,
+                    temp_tf_coolant_peak_field=self.data.tfcoil.tftmp,
+                    data=self.data,
+                )
+            case AvailabilityModel.USER_INPUT | AvailabilityModel.WARD_TAYLOR:
+                temp_margin = self.data.tfcoil.temp_tf_superconductor_margin_min
+
+        self.data.tfcoil.temp_tf_superconductor_margin = temp_margin
 
         # Do current density protection calculation
         # Only setup for Nb3Sn at present.
@@ -2885,10 +2941,10 @@ def tf_cable_in_conduit_superconductor_properties(
         Not used for the CroCo conductor.
 
         """
-        if (
-            SuperconductorModel(i_tf_superconductor).sc_shape
-            != SuperconductorShape.CABLE
-        ):
+        model = SuperconductorModel(i_tf_superconductor)
+        tfcoil = data.tfcoil
+
+        if model.sc_shape != SuperconductorShape.CABLE:
             raise ProcessValueError(
                 "Cannot calculate cable in conduit superconductor properties for "
                 "non-cable superconductors. Change `i_tf_sc_mat` to a cable "
@@ -2896,245 +2952,85 @@ def tf_cable_in_conduit_superconductor_properties(
                 "superconductors."
             )
 
-        # Guard against negative conductor fraction f_a_tf_turn_cable_space_conductor
-        # Kludge to allow solver to continue and hopefully be constrained away
-        # from this point
-        f_a_tf_turn_cable_space_cooling = min(f_a_tf_turn_cable_space_cooling, 0.99)
+        strain = tfcoil.str_tf_con_res if tfcoil.i_str_wp == 0 else tfcoil.str_wp
+        non_copper_fraction = 1.0 - f_a_tf_turn_cable_copper
+        conductor_fraction = 1.0 - min(f_a_tf_turn_cable_space_cooling, 0.99)
 
-        #  Conductor fraction (including central helium channel)
-        f_a_tf_turn_cable_space_conductor = 1.0e0 - f_a_tf_turn_cable_space_cooling
+        conditions = {
+            "temp_conductor": temp_tf_coolant_peak_field,
+            "b_conductor": b_tf_inboard_peak,
+        }
 
-        if data.tfcoil.i_str_wp == 0:
-            strain = data.tfcoil.str_tf_con_res
-        else:
-            strain = data.tfcoil.str_wp
+        # Defaults for models whose current density excludes copper.
+        cable_area = a_tf_turn_cable_space_effective
 
-        # =================================================================
-        match SuperconductorModel(i_tf_superconductor):
-            # ITER Nb3Sn critical surface parameterization
-            case SuperconductorModel.ITER_NB3SN:
-                # Peak field and temperature at zero strain
-                bc20m = SuperconductorModel.ITER_NB3SN.b_crit_zero_field_strain  # [T]
-                tc0m = SuperconductorModel.ITER_NB3SN.temp_crit_zero_field_strain  # [K]
+        match model:
+            case (
+                SuperconductorModel.ITER_NB3SN
+                | SuperconductorModel.USER_DEFINED_NB3SN
+                | SuperconductorModel.WST_NB3SN
+            ):
+                if model == SuperconductorModel.USER_DEFINED_NB3SN:
+                    bc20m, tc0m = bcritsc, tcritsc
+                else:
+                    bc20m = model.b_crit_zero_field_strain
+                    tc0m = model.temp_crit_zero_field_strain
 
-                # If strain limit achieved, throw a warning and use the lower strain
-                if abs(strain) > 0.5e-2:
+                if abs(strain) > 0.005:
                     logger.error(
                         f"TF strain={strain} was outside the region of applicability. "
-                        f"Used lower strain."
+                        "Used lower strain."
                     )
-                    strain = np.sign(strain) * 0.5e-2
+                    strain = np.sign(strain) * 0.005
 
-                #  j_superconductor_critical returned by superconductors.itersc is the
-                # critical current density in the superconductor - not the whole strand,
-                # which contains copper
-                j_superconductor_critical, _, _ = superconductors.itersc(
-                    temp_conductor=temp_tf_coolant_peak_field,
-                    b_conductor=b_tf_inboard_peak,
+                critical_surface = (
+                    superconductors.western_superconducting_nb3sn
+                    if model == SuperconductorModel.WST_NB3SN
+                    else superconductors.itersc
+                )
+                j_superconductor_critical, _, _ = critical_surface(
+                    **conditions,
                     strain=strain,
                     b_c20max=bc20m,
                     temp_c0max=tc0m,
                 )
 
-                # Scale for the copper area fraction of the cable
-                j_cables_critical = j_superconductor_critical * (
-                    1.0e0 - f_a_tf_turn_cable_copper
-                )
-
-                #  Critical current in turn all turn cables
-                c_turn_cables_critical = (
-                    j_cables_critical * a_tf_turn_cable_space_effective
-                )
-
-                # Strand critical current calculation for costing in $/kAm
-                # = Superconducting filaments jc * (1 - strand copper fraction)
-                data.tfcoil.j_crit_str_tf = j_superconductor_critical * (
-                    1.0e0 - f_a_tf_turn_cable_copper
-                )
-
-            # =================================================================
-
-            # Bi-2212 high temperature superconductor parameterization
             case SuperconductorModel.BI2212:
-                #  Current density in a strand of Bi-2212 conductor
-                #  N.B. jcrit returned by superconductors.bi2212 is the critical
-                # current density in the strand, not just the superconducting portion.
-                #  The parameterization for j_crit_cable assumes a particular strand
-                #  composition that does not require a user-defined copper fraction,
-                #  so this is irrelevant in this model
-                j_strand = (
-                    j_tf_wp
-                    * a_tf_turn
-                    / (a_tf_turn_cable_space * f_a_tf_turn_cable_space_conductor)
-                )
-
-                j_crit_cable, _ = superconductors.bi2212(
-                    b_conductor=b_tf_inboard_peak,
+                # This model already accounts for the strand composition.
+                # MC: Comment for reviewers: in this case I imagine it would raise
+                # UnboundLocalError
+                bc20m = tc0m = 0.0
+                cable_area = a_tf_turn_cable_space * conductor_fraction
+                j_strand = j_tf_wp * a_tf_turn / cable_area
+
+                j_cables_critical, _ = superconductors.bi2212(
+                    **conditions,
                     jstrand=j_strand,
-                    temp_conductor=temp_tf_coolant_peak_field,
                     f_strain=f_strain_scale,
                 )
-                j_superconductor_critical = j_crit_cable / (
-                    1.0e0 - f_a_tf_turn_cable_copper
-                )
-                #  Critical current in cable
-                c_turn_cables_critical = (
-                    j_crit_cable
-                    * a_tf_turn_cable_space
-                    * f_a_tf_turn_cable_space_conductor
-                )
-
-                # Strand critical current calulation for costing in $ / kAm
-                # Copper in the strand is already accounted for
-                data.tfcoil.j_crit_str_tf = j_superconductor_critical
-            # =================================================================
+                j_superconductor_critical = j_cables_critical / non_copper_fraction
 
-            # NbTi data
             case SuperconductorModel.OLD_LUBELL_NBTI:
-                bc20m = (
-                    SuperconductorModel.OLD_LUBELL_NBTI.b_crit_zero_field_strain
-                )  # [T]
-                tc0m = (
-                    SuperconductorModel.OLD_LUBELL_NBTI.temp_crit_zero_field_strain
-                )  # [K]
-                c0 = 1.0e10  # [A/m²]
+                bc20m = model.b_crit_zero_field_strain
+                tc0m = model.temp_crit_zero_field_strain
 
                 j_superconductor_critical, _ = superconductors.jcrit_nbti(
-                    temp_conductor=temp_tf_coolant_peak_field,
-                    b_conductor=b_tf_inboard_peak,
-                    c0=c0,
-                    b_c20max=bc20m,
-                    temp_c0max=tc0m,
-                )
-
-                # Scale for the copper area fraction of the cable
-                j_cables_critical = j_superconductor_critical * (
-                    1.0e0 - f_a_tf_turn_cable_copper
-                )
-
-                #  Critical current in turn all turn cables
-                c_turn_cables_critical = (
-                    j_cables_critical * a_tf_turn_cable_space_effective
-                )
-
-                # Strand critical current calulation for costing in $ / kAm
-                # = superconducting filaments jc * (1 -strand copper fraction)
-                data.tfcoil.j_crit_str_tf = j_superconductor_critical * (
-                    1.0e0 - f_a_tf_turn_cable_copper
-                )
-
-            # =================================================================
-
-            # ITER Nb3Sn parameterization, but user-defined parameters
-            case SuperconductorModel.USER_DEFINED_NB3SN:
-                bc20m = bcritsc  # [T]
-                tc0m = tcritsc  # [K]
-
-                # If strain limit achieved, throw a warning and use the lower strain
-                if abs(strain) > 0.5e-2:
-                    logger.error(
-                        f"TF strain={strain} was outside the region of applicability. "
-                        f"Used lower strain."
-                    )
-                    strain = np.sign(strain) * 0.5e-2
-
-                j_superconductor_critical, _, _ = superconductors.itersc(
-                    temp_conductor=temp_tf_coolant_peak_field,
-                    b_conductor=b_tf_inboard_peak,
-                    strain=strain,
+                    **conditions,
+                    c0=1.0e10,
                     b_c20max=bc20m,
                     temp_c0max=tc0m,
                 )
-                # Scale for the copper area fraction of the cable
-                j_cables_critical = j_superconductor_critical * (
-                    1.0e0 - f_a_tf_turn_cable_copper
-                )
-
-                #  Critical current in turn all turn cables
-                c_turn_cables_critical = (
-                    j_cables_critical * a_tf_turn_cable_space_effective
-                )
 
-                # Strand critical current calulation for costing in $ / kAm
-                # = superconducting filaments jc * (1 -strand copper fraction)
-                data.tfcoil.j_crit_str_tf = j_superconductor_critical * (
-                    1.0e0 - f_a_tf_turn_cable_copper
-                )
-
-            # =================================================================
-
-            # WST Nb3Sn parameterisation
-            case SuperconductorModel.WST_NB3SN:
-                bc20m = SuperconductorModel.WST_NB3SN.b_crit_zero_field_strain  # [T]
-                tc0m = SuperconductorModel.WST_NB3SN.temp_crit_zero_field_strain  # [K]
-
-                # If strain limit achieved, throw a warning and use the lower strain
-                if abs(strain) > 0.5e-2:
-                    logger.error(
-                        f"TF strain={strain} was outside the region of applicability. "
-                        f"Used lower strain."
-                    )
-                    strain = np.sign(strain) * 0.5e-2
-
-                #  j_superconductor_critical returned by superconductors.itersc is the
-                # critical current density in the superconductor - not the whole strand,
-                # which contains copper
-                j_superconductor_critical, _, _ = (
-                    superconductors.western_superconducting_nb3sn(
-                        temp_conductor=temp_tf_coolant_peak_field,
-                        b_conductor=b_tf_inboard_peak,
-                        strain=strain,
-                        b_c20max=bc20m,
-                        temp_c0max=tc0m,
-                    )
-                )
-                # Scale for the copper area fraction of the cable
-                j_cables_critical = j_superconductor_critical * (
-                    1.0e0 - f_a_tf_turn_cable_copper
-                )
-
-                #  Critical current in turn all turn cables
-                c_turn_cables_critical = (
-                    j_cables_critical * a_tf_turn_cable_space_effective
-                )
-
-                # Strand critical current calulation for costing in $ / kAm
-                # = superconducting filaments jc * (1 -strand copper fraction)
-                data.tfcoil.j_crit_str_tf = j_superconductor_critical * (
-                    1.0e0 - f_a_tf_turn_cable_copper
-                )
-
-            # =================================================================
-
-            # Durham Ginzburg-Landau Nb-Ti parameterisation
             case SuperconductorModel.DURHAM_NBTI:
-                bc20m = SuperconductorModel.DURHAM_NBTI.b_crit_zero_field_strain  # [T]
-                tc0m = SuperconductorModel.DURHAM_NBTI.temp_crit_zero_field_strain  # [K]
+                bc20m = model.b_crit_zero_field_strain
+                tc0m = model.temp_crit_zero_field_strain
 
                 j_superconductor_critical, _, _ = superconductors.gl_nbti(
-                    temp_conductor=temp_tf_coolant_peak_field,
-                    b_conductor=b_tf_inboard_peak,
+                    **conditions,
                     strain=strain,
                     b_c20max=bc20m,
                     t_c0=tc0m,
                 )
-                # Scale for the copper area fraction of the cable
-                j_cables_critical = j_superconductor_critical * (
-                    1.0e0 - f_a_tf_turn_cable_copper
-                )
-
-                #  Critical current in turn all turn cables
-                c_turn_cables_critical = (
-                    j_cables_critical * a_tf_turn_cable_space_effective
-                )
-
-                # Strand critical current calulation for costing in $ / kAm
-                # = superconducting filaments jc * (1 -strand copper fraction)
-                data.tfcoil.j_crit_str_tf = j_superconductor_critical * (
-                    1.0e0 - f_a_tf_turn_cable_copper
-                )
-
-            # =================================================================
 
             case _:
                 raise ProcessValueError(
@@ -3142,48 +3038,40 @@ def tf_cable_in_conduit_superconductor_properties(
                     i_tf_superconductor=i_tf_superconductor,
                 )
 
-        # =================================================================
-
-        # Critical current density in winding pack
-        # a_tf_turn : Area per turn
-        # (i.e. entire jacketed conductor with insulation) (m2)
-        j_tf_wp_critical = c_turn_cables_critical / a_tf_turn
+        if model == SuperconductorModel.BI2212:
+            # Preserve the original Bi-2212 costing convention.
+            tfcoil.j_crit_str_tf = j_superconductor_critical
+        else:
+            j_cables_critical = j_superconductor_critical * non_copper_fraction
+            tfcoil.j_crit_str_tf = j_cables_critical
 
-        #  Ratio of operating / critical current
+        c_turn_cables_critical = j_cables_critical * cable_area
         f_c_tf_turn_operating_critical = c_tf_turn / c_turn_cables_critical
-
-        #  Operating current density
-        j_tf_coil_turn = c_tf_turn / a_tf_turn
-
-        #  Actual current density in superconductor, not including copper
-
         j_superconductor = f_c_tf_turn_operating_critical * j_superconductor_critical
 
-        # =================================================================
-
-        if f_c_tf_turn_operating_critical <= 0e0:
+        if f_c_tf_turn_operating_critical <= 0.0:
             logger.error(
-                f"""Negative Iop/Icrit for TF coil
-            jsc: {j_superconductor}
-            f_c_tf_turn_operating_critical: {f_c_tf_turn_operating_critical}
-            j_superconductor_critical: {j_superconductor_critical}
-            Check conductor dimensions. Cable space area a_tf_turn_cable_space
-            likely gone negative. a_tf_turn_cable_space: {a_tf_turn_cable_space}
-            This is likely because dr_tf_turn_cable_space or
-            dx_tf_turn_cable_space has gone negative:
-            dr_tf_turn_cable_space:
-            {data.superconducting_tfcoil.dr_tf_turn_cable_space}
-            dx_tf_turn_cable_space:
-            {data.superconducting_tfcoil.dx_tf_turn_cable_space}
-            """
+                f"""Non-positive Iop/Icrit for TF coil
+                jsc: {j_superconductor}
+                f_c_tf_turn_operating_critical: {f_c_tf_turn_operating_critical}
+                j_superconductor_critical: {j_superconductor_critical}
+                Check conductor dimensions. Cable space area a_tf_turn_cable_space
+                likely gone negative. a_tf_turn_cable_space: {a_tf_turn_cable_space}
+                This is likely because dr_tf_turn_cable_space or
+                dx_tf_turn_cable_space has gone negative:
+                dr_tf_turn_cable_space:
+                {data.superconducting_tfcoil.dr_tf_turn_cable_space}
+                dx_tf_turn_cable_space:
+                {data.superconducting_tfcoil.dx_tf_turn_cable_space}
+                """
             )
 
         return TFSuperconductorLimits(
-            j_tf_wp_critical=j_tf_wp_critical,
+            j_tf_wp_critical=c_turn_cables_critical / a_tf_turn,
             j_superconductor_critical=j_superconductor_critical,
             f_c_tf_turn_operating_critical=f_c_tf_turn_operating_critical,
             j_superconductor=j_superconductor,
-            j_tf_coil_turn=j_tf_coil_turn,
+            j_tf_coil_turn=c_tf_turn / a_tf_turn,
             bc20m=bc20m,
             tc0m=tc0m,
             c_turn_cables_critical=c_turn_cables_critical,
@@ -3987,6 +3875,22 @@ def run(self, output: bool = False):
             * self.data.tfcoil.n_tf_coil_turns
         )
 
+        superconductor_margin_properties = self.tf_croco_superconductor_properties(
+            a_tf_turn=self.data.tfcoil.a_tf_turn,
+            b_tf_inboard_peak=self.data.tfcoil.b_tf_inboard_peak_with_ripple,
+            cur_tf_turn=self.data.tfcoil.c_tf_turn,
+            temp_tf_peak=self.data.tfcoil.tftmp
+            + self.data.tfcoil.temp_tf_superconductor_margin_min,
+            i_tf_superconductor=self.data.tfcoil.i_tf_sc_mat,
+            dr_tf_hts_tape=d_sc_tf.dr_tf_hts_tape,
+            dx_tf_hts_tape_rebco=d_sc_tf.dx_tf_hts_tape_rebco,
+            dx_tf_hts_tape_total=d_sc_tf.dx_tf_hts_tape_total,
+            a_tf_croco_strand=d_sc_tf.a_tf_croco_strand,
+        )
+        self.data.tfcoil.j_tf_wp_temp_margin = (
+            superconductor_margin_properties.j_tf_wp_critical
+        )
+
         superconductor_critical_properties = self.tf_croco_superconductor_properties(
             a_tf_turn=self.data.tfcoil.a_tf_turn,
             b_tf_inboard_peak=self.data.tfcoil.b_tf_inboard_peak_with_ripple,
@@ -4021,24 +3925,29 @@ def run(self, output: bool = False):
             superconductor_critical_properties.c_turn_cables_critical
         )
 
-        if self.data.tfcoil.i_str_wp == 0:
-            strain = self.data.tfcoil.str_tf_con_res
-        else:
-            strain = self.data.tfcoil.str_wp
+        match AvailabilityModel(self.data.costs.i_plant_availability):
+            # Only calculate temperature margin if required
+            case AvailabilityModel.MORRIS | AvailabilityModel.ST:
+                if self.data.tfcoil.i_str_wp == 0:
+                    strain = self.data.tfcoil.str_tf_con_res
+                else:
+                    strain = self.data.tfcoil.str_wp
 
-        self.data.tfcoil.temp_tf_superconductor_margin = (
-            self.calculate_superconductor_temperature_margin(
-                i_tf_superconductor=self.data.tfcoil.i_tf_sc_mat,
-                j_superconductor=d_sc_tf.j_tf_superconductor,
-                b_tf_inboard_peak=self.data.tfcoil.b_tf_inboard_peak_with_ripple,
-                strain=strain,
-                bc20m=d_sc_tf.b_tf_superconductor_critical_zero_temp_strain,
-                tc0m=d_sc_tf.temp_tf_superconductor_critical_zero_field_strain,
-                c0=1.0e10,
-                temp_tf_coolant_peak_field=self.data.tfcoil.tftmp,
-                data=self.data,
-            )
-        )
+                temp_margin = self.calculate_superconductor_temperature_margin(
+                    i_tf_superconductor=self.data.tfcoil.i_tf_sc_mat,
+                    j_superconductor=d_sc_tf.j_tf_superconductor,
+                    b_tf_inboard_peak=self.data.tfcoil.b_tf_inboard_peak_with_ripple,
+                    strain=strain,
+                    bc20m=d_sc_tf.b_tf_superconductor_critical_zero_temp_strain,
+                    tc0m=d_sc_tf.temp_tf_superconductor_critical_zero_field_strain,
+                    c0=1.0e10,
+                    temp_tf_coolant_peak_field=self.data.tfcoil.tftmp,
+                    data=self.data,
+                )
+            case AvailabilityModel.USER_INPUT | AvailabilityModel.WARD_TAYLOR:
+                temp_margin = self.data.tfcoil.temp_tf_superconductor_margin_min
+
+        self.data.tfcoil.temp_tf_superconductor_margin = temp_margin
 
         self.data.tfcoil.v_tf_coil_dump_quench_kv = (
             self.croco_voltage() / 1.0e3
@@ -4554,15 +4463,6 @@ def tf_croco_superconductor_properties(
         #  when we have found the desired value of tmarg
         j_superconductor = f_c_tf_turn_operating_critical * j_superconductor_critical
 
-        # Temperature margin
-        current_sharing_t = superconductors.current_sharing_rebco(
-            b_tf_inboard_peak, j_superconductor
-        )
-        tmarg = current_sharing_t - temp_tf_peak
-        self.data.tfcoil.temp_margin = (
-            tmarg  # Only used in the availabilty routine - see comment to Issue #526
-        )
-
         return TFSuperconductorLimits(
             j_tf_wp_critical=j_tf_wp_critical,
             j_superconductor_critical=j_superconductor_critical,
diff --git a/tests/integration/data/large_tokamak_1_MFILE.DAT b/tests/integration/data/large_tokamak_1_MFILE.DAT
index 0ba36d9cd5..2931ed4f94 100644
--- a/tests/integration/data/large_tokamak_1_MFILE.DAT
+++ b/tests/integration/data/large_tokamak_1_MFILE.DAT
@@ -1334,7 +1334,7 @@ fjprot = 1.0
 icc = 36
 ixc = 54 * ftmargtf
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/tests/integration/data/large_tokamak_2_MFILE.DAT b/tests/integration/data/large_tokamak_2_MFILE.DAT
index 640640c6b0..cfc40b0c81 100644
--- a/tests/integration/data/large_tokamak_2_MFILE.DAT
+++ b/tests/integration/data/large_tokamak_2_MFILE.DAT
@@ -1335,7 +1335,7 @@ fjprot = 1.0
 icc = 36
 ixc = 54 * ftmargtf
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/tests/integration/data/large_tokamak_3_MFILE.DAT b/tests/integration/data/large_tokamak_3_MFILE.DAT
index 2c49f31188..67adf75c57 100644
--- a/tests/integration/data/large_tokamak_3_MFILE.DAT
+++ b/tests/integration/data/large_tokamak_3_MFILE.DAT
@@ -1335,7 +1335,7 @@ fjprot = 1.0
 icc = 36
 ixc = 54 * ftmargtf
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/tests/integration/data/large_tokamak_4_MFILE.DAT b/tests/integration/data/large_tokamak_4_MFILE.DAT
index 9748b8980c..af00e406a9 100644
--- a/tests/integration/data/large_tokamak_4_MFILE.DAT
+++ b/tests/integration/data/large_tokamak_4_MFILE.DAT
@@ -1335,7 +1335,7 @@ fjprot = 1.0
 icc = 36
 ixc = 54 * ftmargtf
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/tests/integration/data/large_tokamak_IN.DAT b/tests/integration/data/large_tokamak_IN.DAT
index 16230592e5..6c9514ac9d 100644
--- a/tests/integration/data/large_tokamak_IN.DAT
+++ b/tests/integration/data/large_tokamak_IN.DAT
@@ -94,7 +94,7 @@ icc = 35
 *--------------------------*
 icc = 36
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/tests/integration/data/large_tokamak_MFILE.DAT b/tests/integration/data/large_tokamak_MFILE.DAT
index 2b6c6ef64b..f221e52c6c 100644
--- a/tests/integration/data/large_tokamak_MFILE.DAT
+++ b/tests/integration/data/large_tokamak_MFILE.DAT
@@ -16913,7 +16913,7 @@ icc = 35
 *--------------------------*
 icc = 36
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/tests/integration/data/large_tokamak_eval.IN.DAT b/tests/integration/data/large_tokamak_eval.IN.DAT
index 29ccd473a4..42a25e3fb1 100644
--- a/tests/integration/data/large_tokamak_eval.IN.DAT
+++ b/tests/integration/data/large_tokamak_eval.IN.DAT
@@ -379,7 +379,7 @@ dr_tf_wp_with_insulation = 0.5153787768966674 * radial thickness of winding pack
 dx_tf_turn_steel = 0.008012110032981922 * TF coil conduit case thickness (m) (`iteration variable 58`)
 dx_tf_wp_insulation   = 0.008 * Thickness of the ground insulation layer surrounding (m)
 temp_cs_superconductor_margin_min = 1.5 * minimum allowable temperature margin ; CS (K)
-tmargmin = 1.5 * minimum allowable temperature margin ; TFC AND CS (K)
+temp_tf_superconductor_margin_min = 1.5 * minimum allowable temperature margin ; TF (K)
 v_tf_coil_dump_quench_max_kv    = 10.0 * max voltage across TF coil during quench (kV) (`iteration variable 52`)
 f_a_tf_turn_cable_space_extra_void     = 0.3 * coolant fraction of TFC 'cable' (`i_tf_sup=1`); or of TFC leg (`i_tf_sup=0`)
 flu_tf_neutron_fast_max = 1e22 * max fluence in the TF coil
diff --git a/tests/integration/data/scan_2D_MFILE.DAT b/tests/integration/data/scan_2D_MFILE.DAT
index 6ebf98ee83..c993437740 100644
--- a/tests/integration/data/scan_2D_MFILE.DAT
+++ b/tests/integration/data/scan_2D_MFILE.DAT
@@ -17628,7 +17628,7 @@ fjprot = 1.0
 icc = 36
 ixc = 54 * ftmargtf
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/tests/integration/data/scan_MFILE.DAT b/tests/integration/data/scan_MFILE.DAT
index 0258654bd3..dad7ddace2 100644
--- a/tests/integration/data/scan_MFILE.DAT
+++ b/tests/integration/data/scan_MFILE.DAT
@@ -9292,7 +9292,7 @@ dx_tf_turn_insulation = 2.0d-3 * Conduit insulation thickness (m)
 dr_tf_nose_case   = 0.495 * Inboard tf coil case outer (non-plasma side) thickness (m)
 dx_tf_turn_steel = 0.008 * Tf coil conduit case thickness (m)
 dx_tf_wp_insulation   = 0.008 * Ground insulation thickness surrounding winding pack (m)
-tmargmin = 1.500 * Minimum allowable temperature margin (cs and tf coils) (k)
+temp_tf_superconductor_margin_min = 1.5 * Minimum allowable temperature margin (TF coils) (k)
 v_tf_coil_dump_quench_max_kv    = 10.00 * Max voltage across tf coil during quench (kv)
 f_a_tf_turn_cable_space_extra_void     = 0.300 * Coolant fraction of tfc 'cable' (i_tf_sup=1); or of tfc leg (i_tf_sup=0)
 i_tf_sc_mat = 5
diff --git a/tests/regression/input_files/large_tokamak_eval.IN.DAT b/tests/regression/input_files/large_tokamak_eval.IN.DAT
index d9128b7218..00e4eadbe8 100644
--- a/tests/regression/input_files/large_tokamak_eval.IN.DAT
+++ b/tests/regression/input_files/large_tokamak_eval.IN.DAT
@@ -382,7 +382,7 @@ dr_tf_wp_with_insulation = 0.5153787768966674 * radial thickness of winding pack
 dx_tf_turn_steel = 0.008012110032981922 * TF coil conduit case thickness (m) (`iteration variable 58`)
 dx_tf_wp_insulation   = 0.008 * Thickness of the ground insulation layer surrounding (m)
 temp_cs_superconductor_margin_min = 1.5 * minimum allowable temperature margin ; CS (K)
-tmargmin = 1.5 * minimum allowable temperature margin ; TFC AND CS (K)
+temp_tf_superconductor_margin_min = 1.5 * minimum allowable temperature margin ; TF (K)
 v_tf_coil_dump_quench_max_kv    = 10.0 * max voltage across TF coil during quench (kV) (`iteration variable 52`)
 f_a_tf_turn_cable_space_extra_void     = 0.3 * coolant fraction of TFC 'cable' (`i_tf_sup=1`); or of TFC leg (`i_tf_sup=0`)
 flu_tf_neutron_fast_max = 1e22 * max fluence in the TF coil
diff --git a/tests/regression/input_files/large_tokamak_nof.IN.DAT b/tests/regression/input_files/large_tokamak_nof.IN.DAT
index 203363dad0..66cfa56193 100644
--- a/tests/regression/input_files/large_tokamak_nof.IN.DAT
+++ b/tests/regression/input_files/large_tokamak_nof.IN.DAT
@@ -103,7 +103,7 @@ icc = 35
 *--------------------------*
 icc = 36
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5 * minimum allowable temperature margin ; TF (K)
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/tests/regression/input_files/low_aspect_ratio_DEMO.IN.DAT b/tests/regression/input_files/low_aspect_ratio_DEMO.IN.DAT
index af4872e2a9..163f9ed82e 100644
--- a/tests/regression/input_files/low_aspect_ratio_DEMO.IN.DAT
+++ b/tests/regression/input_files/low_aspect_ratio_DEMO.IN.DAT
@@ -940,12 +940,12 @@ dx_tf_wp_insulation   = 0.008
 * DESCRIPTION:   Ground insulation thickness surrounding winding pack (m)
 * JUSTIFICATION: 
 
-tmargmin = 1.500
-* DESCRIPTION:   Minimum allowable temperature margin (cs and tf coils) (k)
+temp_tf_superconductor_margin_min = 1.5
+* DESCRIPTION:   Minimum allowable temperature margin (TF coils) (k)
 * JUSTIFICATION: 
 
-*t_margmin_cs = 1.500
-* DESCRIPTION:   Minimum allowable temperature margin (cs and tf coils) (k)
+temp_cs_superconductor_margin_min = 1.5
+* DESCRIPTION:   Minimum allowable temperature margin (CS) (k)
 * JUSTIFICATION: 
 
 f_a_tf_turn_cable_space_extra_void = 0.300
diff --git a/tests/regression/input_files/stellarator_helias.IN.DAT b/tests/regression/input_files/stellarator_helias.IN.DAT
index 73480c5d80..d97f5c091d 100644
--- a/tests/regression/input_files/stellarator_helias.IN.DAT
+++ b/tests/regression/input_files/stellarator_helias.IN.DAT
@@ -233,8 +233,8 @@ runtitle = SQuID
 *-----------------Tfcoil Variables-----------------*
 
 i_tf_sc_mat = 1         * Switch for superconductor material in tf coils (1: ITER Nb3Sn)
-tftmp     = 4.5         * Peak helium coolant temperature in TF coils and PF coils (K)
-tmargmin = 1.5          * Temperature margin for superconductor current density calculation (K)
+tftmp     = 4.5         * Peak helium coolant temperature in TF coils and PF coils (K)         
+temp_tf_superconductor_margin_min = 1.5   * Temperature margin for superconductor current density calculation (K)
 temp_tf_cryo = 4.5      * Coil temperature for cryogenic plant power calculation (K)
 dx_tf_turn_general = 0.056                * Dimension conductor area including steel and insulation.
 dx_tf_turn_insulation = 0.002             * Conduit insulation thickness (m)
diff --git a/tests/unit/data/large_tokamak_IN.DAT b/tests/unit/data/large_tokamak_IN.DAT
index 16230592e5..6c9514ac9d 100644
--- a/tests/unit/data/large_tokamak_IN.DAT
+++ b/tests/unit/data/large_tokamak_IN.DAT
@@ -94,7 +94,7 @@ icc = 35
 *--------------------------*
 icc = 36
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/tests/unit/data/large_tokamak_MFILE.DAT b/tests/unit/data/large_tokamak_MFILE.DAT
index 4fbc61943a..67fa4c827b 100644
--- a/tests/unit/data/large_tokamak_MFILE.DAT
+++ b/tests/unit/data/large_tokamak_MFILE.DAT
@@ -7752,7 +7752,7 @@ fjprot = 1.0
 icc = 36
 ixc = 54 * ftmargtf
 * Minimum allowable temperature margin [K]
-tmargmin = 1.5
+temp_tf_superconductor_margin_min = 1.5
 
 * CS coil temp margin lower limit *
 *---------------------------------*
diff --git a/tests/unit/models/test_availability.py b/tests/unit/models/test_availability.py
index d21009b306..2cac59f934 100644
--- a/tests/unit/models/test_availability.py
+++ b/tests/unit/models/test_availability.py
@@ -238,7 +238,7 @@ def calc_u_unplanned_magnets_param(**kwargs):
     :rtype: dict
     """
     defaults = {
-        "temp_margin": 1.5,
+        "temp_tf_superconductor_margin": 1.5,
         "temp_tf_superconductor_margin_min": 1.5,
         "temp_cs_superconductor_margin_min": 1.5,
         "t_plant_operational_total_yrs": 30,
@@ -264,13 +264,13 @@ def calc_u_unplanned_magnets_params():
     return [
         calc_u_unplanned_magnets_param(),
         calc_u_unplanned_magnets_param(
-            temp_margin=2.0,
+            temp_tf_superconductor_margin=2.0,
             temp_tf_superconductor_margin_min=1.6,
             temp_cs_superconductor_margin_min=1.6,
             conf_mag=0.8,
         ),
         calc_u_unplanned_magnets_param(
-            temp_margin=1.8,
+            temp_tf_superconductor_margin=1.8,
             temp_tf_superconductor_margin_min=1.6,
             temp_cs_superconductor_margin_min=1.6,
             conf_mag=0.8,
@@ -314,7 +314,11 @@ def calc_u_unplanned_magnets_fix(availability, request, monkeypatch):
         "temp_tf_superconductor_margin_min",
         param["temp_tf_superconductor_margin_min"],
     )
-    monkeypatch.setattr(availability.data.tfcoil, "temp_margin", param["temp_margin"])
+    monkeypatch.setattr(
+        availability.data.tfcoil,
+        "temp_tf_superconductor_margin",
+        param["temp_tf_superconductor_margin"],
+    )
 
     return param["expected"]
 
diff --git a/tests/unit/models/test_superconductors.py b/tests/unit/models/test_superconductors.py
index 393ec37e98..3321d31838 100644
--- a/tests/unit/models/test_superconductors.py
+++ b/tests/unit/models/test_superconductors.py
@@ -154,12 +154,6 @@ def test_jcrit_rebco():
     assert validity
 
 
-def test_current_sharing_rebco():
-    assert superconductors.current_sharing_rebco(11.0, 2e7) == pytest.approx(
-        71.28702697627514
-    )
-
-
 def test_bi2212():
     jcrit, tmarg = superconductors.bi2212(7.0, 2e7, 4.75, 0.2)
 
diff --git a/tests/unit/models/tfcoil/test_sctfcoil.py b/tests/unit/models/tfcoil/test_sctfcoil.py
index efcc160e77..ca94fc92cc 100644
--- a/tests/unit/models/tfcoil/test_sctfcoil.py
+++ b/tests/unit/models/tfcoil/test_sctfcoil.py
@@ -149,9 +149,9 @@ def test_protect(protectparam, sctfcoil):
 class SuperconParam(NamedTuple):
     temp_tf_superconductor_margin_min: Any = None
 
-    n_tf_coils: Any = None
+    temp_tf_superconductor_margin: Any = None
 
-    temp_margin: Any = None
+    n_tf_coils: Any = None
 
     dia_tf_turn_coolant_channel: Any = None
 
@@ -213,7 +213,7 @@ class SuperconParam(NamedTuple):
 
     tcritsc: Any = None
 
-    expected_temp_margin: Any = None
+    expected_temp_tf_superconductor_margin: Any = None
 
     expected_j_tf_wp_quench_heat_max: Any = None
 
@@ -242,7 +242,7 @@ class SuperconParam(NamedTuple):
         SuperconParam(
             temp_tf_superconductor_margin_min=1.5,
             n_tf_coils=16,
-            temp_margin=0,
+            temp_tf_superconductor_margin=0,
             dia_tf_turn_coolant_channel=0.010000000000000002,
             c_tf_turn=74026.751437500003,
             b_tf_inboard_peak_with_ripple=12.48976756562082,
@@ -275,7 +275,7 @@ class SuperconParam(NamedTuple):
             detection_time=0.0,
             bcritsc=24,
             tcritsc=16,
-            expected_temp_margin=2.864553846654988,
+            expected_temp_tf_superconductor_margin=2.864553846654988,
             expected_j_tf_wp_quench_heat_max=17213147.288375787,
             expected_j_tf_wp_critical=49719296.722920775,
             expected_vd=9988.2637896807955,
@@ -290,7 +290,7 @@ class SuperconParam(NamedTuple):
         SuperconParam(
             temp_tf_superconductor_margin_min=1.5,
             n_tf_coils=16,
-            temp_margin=2.3431632224075836,
+            temp_tf_superconductor_margin=2.3431632224075836,
             dia_tf_turn_coolant_channel=0.010000000000000002,
             c_tf_turn=74026.751437500003,
             b_tf_inboard_peak_with_ripple=12.48976756562082,
@@ -321,7 +321,7 @@ class SuperconParam(NamedTuple):
             detection_time=0.0,
             bcritsc=24,
             tcritsc=16,
-            expected_temp_margin=2.864553846654988,
+            expected_temp_tf_superconductor_margin=2.864553846654988,
             expected_j_tf_wp_quench_heat_max=17213147.288375787,
             expected_j_tf_wp_critical=49719296.722920775,
             expected_vd=10001.287165953383,
@@ -363,7 +363,9 @@ def test_supercon(superconparam, monkeypatch, cicc_sctfcoil):
     )
 
     monkeypatch.setattr(
-        cicc_sctfcoil.data.tfcoil, "temp_margin", superconparam.temp_margin
+        cicc_sctfcoil.data.tfcoil,
+        "temp_tf_superconductor_margin",
+        superconparam.temp_tf_superconductor_margin,
     )
 
     monkeypatch.setattr(cicc_sctfcoil.data.tfcoil, "rrr_tf_cu", superconparam.cu_rrr)