diff --git a/documentation/scripts/plotting_scripts/2nd_gen_rebco_critical_surface.py b/documentation/scripts/plotting_scripts/2nd_gen_rebco_critical_surface.py
index 20252f631f..fba5d0ba40 100644
--- a/documentation/scripts/plotting_scripts/2nd_gen_rebco_critical_surface.py
+++ b/documentation/scripts/plotting_scripts/2nd_gen_rebco_critical_surface.py
@@ -5,11 +5,14 @@
 import plotly.graph_objects as go
 
 from process.models import superconductors
+from process.models.superconductors import SuperconductorModel
 
-temp_c0max = 90.0  # Critical temperature (K) at zero field and strain
+temp_c0max = (
+    SuperconductorModel.CROCO_REBCO.temp_crit_zero_field_strain
+)  # Critical temperature (K) at zero field and strain
 b_c20max = (
-    132.5  # Upper critical field (T) for superconductor at zero temperature and strain
-)
+    SuperconductorModel.CROCO_REBCO.b_crit_zero_field_strain
+)  # Upper critical field (T) for superconductor at zero temperature and strain
 epsilon = 0.00  # Strain in superconductor
 
 # Create a grid of temperature and field values
@@ -26,7 +29,12 @@
             _,
             _,
             _,
-        ) = superconductors.jcrit_rebco(temp_grid[i, j], b_grid[i, j])
+        ) = superconductors.jcrit_rebco(
+            temp_conductor=temp_grid[i, j],
+            b_conductor=b_grid[i, j],
+            b_c20_max=b_c20max,
+            temp_c0_max=temp_c0max,
+        )
         # Convert from A/m² to kA/mm² (1 A/m² = 1e-6 A/mm²)
         j_scaling[i, j] *= 1e-9
         print(f"j_scaling[{i}, {j}] = {j_scaling[i, j]} kA/mm²")
diff --git a/documentation/scripts/plotting_scripts/durham_nbti_critical_surface.py b/documentation/scripts/plotting_scripts/durham_nbti_critical_surface.py
index b54ad80008..047c04ec76 100644
--- a/documentation/scripts/plotting_scripts/durham_nbti_critical_surface.py
+++ b/documentation/scripts/plotting_scripts/durham_nbti_critical_surface.py
@@ -5,6 +5,7 @@
 import plotly.graph_objects as go
 
 from process.models import superconductors
+from process.models.superconductors import SuperconductorModel
 
 # Create a grid of temperature and field values
 temp_conductor = np.linspace(1, 8.0, 50)  # Temperature range (K)
@@ -23,8 +24,8 @@
             temp_conductor=temp_grid[i, j],
             b_conductor=b_grid[i, j],
             strain=0.0,
-            b_c20max=14.9,
-            t_c0=9.0,
+            b_c20max=SuperconductorModel.DURHAM_NBTI.b_crit_zero_field_strain,
+            t_c0=SuperconductorModel.DURHAM_NBTI.temp_crit_zero_field_strain,
         )
         # Convert from A/m² to kA/mm² (1 A/m² = 1e-6 A/mm²)
         j_scaling[i, j] *= 1e-9
diff --git a/documentation/scripts/plotting_scripts/durham_rebco_critical_surface.py b/documentation/scripts/plotting_scripts/durham_rebco_critical_surface.py
index 5de14533a9..d513d5b8ed 100644
--- a/documentation/scripts/plotting_scripts/durham_rebco_critical_surface.py
+++ b/documentation/scripts/plotting_scripts/durham_rebco_critical_surface.py
@@ -5,6 +5,7 @@
 import plotly.graph_objects as go
 
 from process.models import superconductors
+from process.models.superconductors import SuperconductorModel
 
 # Create a grid of temperature and field values
 temp_conductor = np.linspace(4.2, 30.0, 50)  # Temperature range (K)
@@ -23,8 +24,8 @@
             temp_conductor=temp_grid[i, j],
             b_conductor=b_grid[i, j],
             strain=0.0,
-            b_c20max=429.0,
-            t_c0=185.0,
+            b_c20max=SuperconductorModel.DURHAM_REBCO.b_crit_zero_field_strain,
+            t_c0=SuperconductorModel.DURHAM_REBCO.temp_crit_zero_field_strain,
         )
         # Convert from A/m² to kA/mm² (1 A/m² = 1e-6 A/mm²)
         j_scaling[i, j] *= 1e-9
diff --git a/documentation/scripts/plotting_scripts/eutf4_nb3sn_critical_surface.py b/documentation/scripts/plotting_scripts/eutf4_nb3sn_critical_surface.py
index 162080fca1..6269cb5cc3 100644
--- a/documentation/scripts/plotting_scripts/eutf4_nb3sn_critical_surface.py
+++ b/documentation/scripts/plotting_scripts/eutf4_nb3sn_critical_surface.py
@@ -5,11 +5,15 @@
 import plotly.graph_objects as go
 
 from process.models import superconductors
+from process.models.superconductors import SuperconductorModel
+
+# Upper critical field (T) for superconductor at zero temperature and strain
+b_c20max = SuperconductorModel.ITER_NB3SN.b_crit_zero_field_strain
+
+temp_c0max = (
+    SuperconductorModel.ITER_NB3SN.temp_crit_zero_field_strain
+)  # Critical temperature (K) at zero field and strain
 
-temp_c0max = 16.06  # Critical temperature (K) at zero field and strain
-b_c20max = (
-    32.97  # Upper critical field (T) for superconductor at zero temperature and strain
-)
 epsilon = 0.00  # Strain in superconductor
 
 # Create a grid of temperature and field values
diff --git a/documentation/scripts/plotting_scripts/hazelton_zhai_rebco_critical_surface.py b/documentation/scripts/plotting_scripts/hazelton_zhai_rebco_critical_surface.py
index dddd17b688..8ad53caeb2 100644
--- a/documentation/scripts/plotting_scripts/hazelton_zhai_rebco_critical_surface.py
+++ b/documentation/scripts/plotting_scripts/hazelton_zhai_rebco_critical_surface.py
@@ -5,6 +5,7 @@
 import plotly.graph_objects as go
 
 from process.models import superconductors
+from process.models.superconductors import SuperconductorModel
 
 # Create a grid of temperature and field values
 temp_conductor = np.linspace(4.2, 40.0, 50)  # Temperature range (K)
@@ -22,8 +23,8 @@
         ) = superconductors.hijc_rebco(
             temp_conductor=temp_grid[i, j],
             b_conductor=b_grid[i, j],
-            b_c20max=138.0,
-            t_c0=92.0,
+            b_c20max=SuperconductorModel.HAZELTON_ZHAI_REBCO.b_crit_zero_field_strain,
+            t_c0=SuperconductorModel.HAZELTON_ZHAI_REBCO.temp_crit_zero_field_strain,
             tape_width=1.0,
             rebco_thickness=1.0,
             tape_thickness=1.0,
diff --git a/documentation/scripts/plotting_scripts/old_empirical_nbti_critical_surface.py b/documentation/scripts/plotting_scripts/old_empirical_nbti_critical_surface.py
index 53e96b8f93..cb380ed60f 100644
--- a/documentation/scripts/plotting_scripts/old_empirical_nbti_critical_surface.py
+++ b/documentation/scripts/plotting_scripts/old_empirical_nbti_critical_surface.py
@@ -5,6 +5,7 @@
 import plotly.graph_objects as go
 
 from process.models import superconductors
+from process.models.superconductors import SuperconductorModel
 
 # Create a grid of temperature and field values
 temp_conductor = np.linspace(1, 10.0, 50)  # Temperature range (K)
@@ -22,8 +23,8 @@
             temp_conductor=temp_grid[i, j],
             b_conductor=b_grid[i, j],
             c0=1e10,
-            b_c20max=15.0,
-            temp_c0max=9.3,
+            b_c20max=SuperconductorModel.OLD_LUBELL_NBTI.b_crit_zero_field_strain,
+            temp_c0max=SuperconductorModel.OLD_LUBELL_NBTI.temp_crit_zero_field_strain,
         )
         # Convert from A/m² to kA/mm² (1 A/m² = 1e-6 A/mm²)
         j_scaling[i, j] *= 1e-9
diff --git a/documentation/scripts/plotting_scripts/western_nb3sn_critical_surface.py b/documentation/scripts/plotting_scripts/western_nb3sn_critical_surface.py
index 10d0fafd95..133e756225 100644
--- a/documentation/scripts/plotting_scripts/western_nb3sn_critical_surface.py
+++ b/documentation/scripts/plotting_scripts/western_nb3sn_critical_surface.py
@@ -7,11 +7,14 @@
 import plotly.graph_objects as go
 
 from process.models import superconductors
+from process.models.superconductors import SuperconductorModel
 
-temp_c0max = 16.34  # Critical temperature (K) at zero field and strain
+temp_c0max = (
+    SuperconductorModel.WST_NB3SN.temp_crit_zero_field_strain
+)  # Critical temperature (K) at zero field and strain
 b_c20max = (
-    33.24  # Upper critical field (T) for superconductor at zero temperature and strain
-)
+    SuperconductorModel.WST_NB3SN.b_crit_zero_field_strain
+)  # Upper critical field (T) for superconductor at zero temperature and strain
 epsilon = 0.00  # Strain in superconductor
 
 # Create a grid of temperature and field values
diff --git a/process/core/input.py b/process/core/input.py
index bf30712004..2a7b4c6df3 100644
--- a/process/core/input.py
+++ b/process/core/input.py
@@ -216,7 +216,6 @@ def bounds(self) -> tuple[NumberType | None, NumberType | None]:
     "auxcool_w": InputVariable("buildings", float, range=(10.0, 1000.0)),
     "p_hcd_injected_min_mw": InputVariable("constraints", float, range=(0.01, 100.0)),
     "f_t_plant_available_min": InputVariable("costs", float, range=(0.0, 1.0)),
-    "b_crit_upper_nbti": InputVariable("tfcoil", float, range=(0.0, 30.0)),
     "p_plant_electric_base": InputVariable(
         "heat_transport", float, range=(1000000.0, 10000000000.0)
     ),
@@ -781,7 +780,6 @@ def bounds(self) -> tuple[NumberType | None, NumberType | None]:
     "dx_tf_turn_cable_space_general": InputVariable("tfcoil", float, range=(0.0, 0.1)),
     "t_crack_radial": InputVariable("cs_fatigue", float, range=(1e-05, 1.0)),
     "t_crack_vertical": InputVariable("cs_fatigue", float, range=(1e-05, 1.0)),
-    "t_crit_nbti": InputVariable("tfcoil", float, range=(0.0, 15.0)),
     "t_plant_pulse_plasma_current_ramp_up": InputVariable(
         "times", float, range=(0.0, 10000.0)
     ),
diff --git a/process/data_structure/tfcoil_variables.py b/process/data_structure/tfcoil_variables.py
index 985bb09b79..1e9bdb5a55 100644
--- a/process/data_structure/tfcoil_variables.py
+++ b/process/data_structure/tfcoil_variables.py
@@ -184,12 +184,6 @@ class TFData:
     e_tf_coil_magnetic_stored: float = 0.0
     """Stored magnetic energy in a single TF coil (J)"""
 
-    b_crit_upper_nbti: float = 14.86
-    """upper critical field of GL_nbti"""
-
-    t_crit_nbti: float = 9.04
-    """critical temperature of GL_nbti"""
-
     max_force_density: float = 0.0
     """Maximal (WP averaged) force density in TF coils at 1 point. (MN/m3)"""
 
diff --git a/process/models/pfcoil.py b/process/models/pfcoil.py
index 2343d3fde3..a36ddb6881 100644
--- a/process/models/pfcoil.py
+++ b/process/models/pfcoil.py
@@ -886,8 +886,6 @@ def pfcoil(self):
                             temp_pf_peak_field=self.data.tfcoil.tftmp,
                             bcritsc=self.data.tfcoil.bcritsc,
                             tcritsc=self.data.tfcoil.tcritsc,
-                            b_crit_upper_nbti=self.data.tfcoil.b_crit_upper_nbti,
-                            t_crit_nbti=self.data.tfcoil.t_crit_nbti,
                             dr_hts_tape=self.data.superconducting_tfcoil.dr_tf_hts_tape,
                             dx_hts_tape_rebco=self.data.superconducting_tfcoil.dx_tf_hts_tape_rebco,
                             dx_hts_tape_total=self.data.superconducting_tfcoil.dx_tf_hts_tape_total,
@@ -3610,8 +3608,6 @@ def ohcalc(self):
                 temp_pf_peak_field=self.data.pf_coil.temp_cs_superconductor_operating,
                 bcritsc=self.data.tfcoil.bcritsc,
                 tcritsc=self.data.tfcoil.tcritsc,
-                b_crit_upper_nbti=self.data.tfcoil.b_crit_upper_nbti,
-                t_crit_nbti=self.data.tfcoil.t_crit_nbti,
                 dr_hts_tape=self.data.superconducting_tfcoil.dr_tf_hts_tape,
                 dx_hts_tape_rebco=self.data.superconducting_tfcoil.dx_tf_hts_tape_rebco,
                 dx_hts_tape_total=self.data.superconducting_tfcoil.dx_tf_hts_tape_total,
@@ -3660,8 +3656,6 @@ def ohcalc(self):
                 temp_pf_peak_field=self.data.pf_coil.temp_cs_superconductor_operating,
                 bcritsc=self.data.tfcoil.bcritsc,
                 tcritsc=self.data.tfcoil.tcritsc,
-                b_crit_upper_nbti=self.data.tfcoil.b_crit_upper_nbti,
-                t_crit_nbti=self.data.tfcoil.t_crit_nbti,
                 dr_hts_tape=self.data.superconducting_tfcoil.dr_tf_hts_tape,
                 dx_hts_tape_rebco=self.data.superconducting_tfcoil.dx_tf_hts_tape_rebco,
                 dx_hts_tape_total=self.data.superconducting_tfcoil.dx_tf_hts_tape_total,
@@ -4649,8 +4643,6 @@ def superconpf(
     temp_pf_peak_field: float,
     bcritsc: float,
     tcritsc: float,
-    b_crit_upper_nbti: float,
-    t_crit_nbti: float,
     dr_hts_tape: float,
     dx_hts_tape_rebco: float,
     dx_hts_tape_total: float,
@@ -4698,10 +4690,6 @@ def superconpf(
         Critical field at zero temperature and strain [T] (isumat=4 only)
     tcritsc : float
         Critical temperature at zero field and strain [K] (isumat=4 only)
-    b_crit_upper_nbti: float
-        upper critical field of GL_nbti [T]
-    t_crit_nbti: float
-        critical temperature of GL_nbti [K]
     dr_hts_tape: float
         Mean width of tape [m]
     dx_hts_tape_rebco: float
@@ -4733,8 +4721,12 @@ def j_crit_cable_frac(j_crit_sc, fcu, fhe):
     # Find critical current density in superconducting strand, jcritstr
     if isumat == SuperconductorModel.ITER_NB3SN:
         # ITER Nb3Sn critical surface parameterization
-        bc20m = 32.97e0  # [T] critical field at 0 K and 0 strain
-        tc0m = 16.06e0  # [K] critical temperature at 0 T and 0 strain
+        bc20m = (
+            SuperconductorModel.ITER_NB3SN.b_crit_zero_field_strain
+        )  # [T] critical field at 0 K and 0 strain
+        tc0m = (
+            SuperconductorModel.ITER_NB3SN.temp_crit_zero_field_strain
+        )  # [K] critical temperature at 0 T and 0 strain
 
         # j_crit_sc returned by superconductors.itersc is
         # the critical current density in the superconductor
@@ -4772,8 +4764,12 @@ def j_crit_cable_frac(j_crit_sc, fcu, fhe):
 
     elif isumat == SuperconductorModel.OLD_LUBELL_NBTI:
         # NbTi data
-        bc20m = 15.0e0  # [T] critical field at 0 K and 0 strain
-        tc0m = 9.3e0  # [K] critical temperature at 0 T and 0 strain
+        bc20m = (
+            SuperconductorModel.OLD_LUBELL_NBTI.b_crit_zero_field_strain
+        )  # [T] critical field at 0 K and 0 strain
+        tc0m = (
+            SuperconductorModel.OLD_LUBELL_NBTI.temp_crit_zero_field_strain
+        )  # [K] critical temperature at 0 T and 0 strain
         c0 = 1.0e10  # # [A/m²]
         j_crit_sc, _ = superconductors.jcrit_nbti(
             temp_conductor=temp_pf_peak_field,
@@ -4799,8 +4795,12 @@ def j_crit_cable_frac(j_crit_sc, fcu, fhe):
 
     elif isumat == SuperconductorModel.WST_NB3SN:
         # WST Nb3Sn parameterisation
-        bc20m = 32.97e0  # [T] critical field at 0 K and 0 strain
-        tc0m = 16.06e0  # [K] critical temperature at 0 T and 0 strain
+        bc20m = (
+            SuperconductorModel.WST_NB3SN.b_crit_zero_field_strain
+        )  # [T] critical field at 0 K and 0 strain
+        tc0m = (
+            SuperconductorModel.WST_NB3SN.temp_crit_zero_field_strain
+        )  # [K] critical temperature at 0 T and 0 strain
 
         # j_crit_sc returned by superconductors.itersc is the critical current density
         # in the superconductor - not the whole strand, which contains copper
@@ -4815,16 +4815,29 @@ def j_crit_cable_frac(j_crit_sc, fcu, fhe):
         j_crit_cable = j_crit_cable_frac(j_crit_sc, fcu, fhe)
 
     elif isumat == SuperconductorModel.CROCO_REBCO:
-        # "REBCO" 2nd generation HTS superconductor in CroCo strand
+        # "REBCO" 2nd generation HTS superconductor in CrCo strand
+        b_c20m = (
+            SuperconductorModel.CROCO_REBCO.b_crit_zero_field_strain
+        )  # [T] critical field at 0 K and 0 strain
+        t_c0m = (
+            SuperconductorModel.CROCO_REBCO.temp_crit_zero_field_strain
+        )  # [K] critical temperature at 0 T and 0 strain
         j_crit_sc, _, _, _ = superconductors.jcrit_rebco(
-            temp_conductor=temp_pf_peak_field, b_conductor=b_pf_peak
+            temp_conductor=temp_pf_peak_field,
+            b_conductor=b_pf_peak,
+            b_c20_max=b_c20m,
+            temp_c0_max=t_c0m,
         )
         j_crit_cable = j_crit_cable_frac(j_crit_sc, fcu, fhe)
 
     elif isumat == SuperconductorModel.DURHAM_NBTI:
         # Durham Ginzburg-Landau critical surface model for Nb-Ti
-        bc20m = b_crit_upper_nbti  # [T] critical field at 0 K and 0 strain
-        tc0m = t_crit_nbti  # [K] critical temperature at 0 T and 0 strain
+        bc20m = (
+            SuperconductorModel.DURHAM_NBTI.b_crit_zero_field_strain
+        )  # [T] critical field at 0 K and 0 strain
+        tc0m = (
+            SuperconductorModel.DURHAM_NBTI.temp_crit_zero_field_strain
+        )  # [K] critical temperature at 0 T and 0 strain
         j_crit_sc, _, _ = superconductors.gl_nbti(
             temp_conductor=temp_pf_peak_field,
             b_conductor=b_pf_peak,
@@ -4836,8 +4849,12 @@ def j_crit_cable_frac(j_crit_sc, fcu, fhe):
 
     elif isumat == SuperconductorModel.DURHAM_REBCO:
         # Durham Ginzburg-Landau critical surface model for REBCO
-        bc20m = 429e0  # [T] critical field at 0 K and 0 strain
-        tc0m = 185e0  # [K] critical temperature at 0 T and 0 strain
+        bc20m = (
+            SuperconductorModel.DURHAM_REBCO.b_crit_zero_field_strain
+        )  # [T] critical field at 0 K and 0 strain
+        tc0m = (
+            SuperconductorModel.DURHAM_REBCO.temp_crit_zero_field_strain
+        )  # [K] critical temperature at 0 T and 0 strain
         j_crit_sc, _, _ = superconductors.gl_rebco(
             temp_conductor=temp_pf_peak_field,
             b_conductor=b_pf_peak,
@@ -4850,8 +4867,12 @@ def j_crit_cable_frac(j_crit_sc, fcu, fhe):
 
     elif isumat == SuperconductorModel.HAZELTON_ZHAI_REBCO:
         # Hazelton experimental data + Zhai conceptual model for REBCO
-        bc20m = 138  # [T] critical field at 0 K and 0 strain
-        tc0m = 92  # [K] critical temperature at 0 T and 0 strain
+        bc20m = (
+            SuperconductorModel.HAZELTON_ZHAI_REBCO.b_crit_zero_field_strain
+        )  # [T] critical field at 0 K and 0 strain
+        tc0m = (
+            SuperconductorModel.HAZELTON_ZHAI_REBCO.temp_crit_zero_field_strain
+        )  # [K] critical temperature at 0 T and 0 strain
         j_crit_sc, _, _ = superconductors.hijc_rebco(
             temp_conductor=temp_pf_peak_field,
             b_conductor=b_pf_peak,
diff --git a/process/models/stellarator/coils/calculate.py b/process/models/stellarator/coils/calculate.py
index cefdf71da7..bb273f81c3 100644
--- a/process/models/stellarator/coils/calculate.py
+++ b/process/models/stellarator/coils/calculate.py
@@ -419,11 +419,9 @@ def winding_pack_total_size(
             b_max_k[k],
             data.tfcoil.tftmp + data.tfcoil.tmargmin,
             data.tfcoil.i_tf_sc_mat,
-            data.tfcoil.b_crit_upper_nbti,
             data.tfcoil.bcritsc,
             data.tfcoil.f_a_tf_turn_cable_copper,
             data.tfcoil.fhts,
-            data.tfcoil.t_crit_nbti,
             data.tfcoil.tcritsc,
             data.tfcoil.f_a_tf_turn_cable_space_extra_void,
             data.tfcoil.j_tf_wp,
diff --git a/process/models/stellarator/coils/coils.py b/process/models/stellarator/coils/coils.py
index e5e7394a95..fd927eaf6b 100644
--- a/process/models/stellarator/coils/coils.py
+++ b/process/models/stellarator/coils/coils.py
@@ -7,6 +7,7 @@
 from process.core.exceptions import ProcessValueError
 from process.core.model import DataStructure
 from process.models import superconductors
+from process.models.superconductors import SuperconductorModel
 
 logger = logging.getLogger(__name__)
 
@@ -23,11 +24,9 @@ def jcrit_from_material(
     b_max,
     t_helium,
     i_tf_sc_mat,
-    b_crit_upper_nbti,
     b_crit_sc,
     f_a_tf_turn_cable_copper,
     f_hts,
-    t_crit_nbti,
     t_crit_sc,
     f_a_tf_turn_cable_space_extra_void,
     j_wp,
@@ -49,9 +48,11 @@ def jcrit_from_material(
     )
     # of a cable conductor.
 
-    if i_tf_sc_mat == 1:  # ITER Nb3Sn critical surface parameterization
-        bc20m = 32.97  # these are values taken from sctfcoil.f90
-        tc0m = 16.06
+    if (
+        i_tf_sc_mat == SuperconductorModel.ITER_NB3SN
+    ):  # ITER Nb3Sn critical surface parameterization
+        bc20m = SuperconductorModel.ITER_NB3SN.b_crit_zero_field_strain
+        tc0m = SuperconductorModel.ITER_NB3SN.temp_crit_zero_field_strain
 
         #  j_crit_sc returned by itersc is the critical current density in the
         #  superconductor - not the whole strand, which contains copper
@@ -70,7 +71,7 @@ def jcrit_from_material(
         j_crit_sc = max(1.0e-9, j_crit_sc)
         j_crit_cable = max(1.0e-9, j_crit_cable)
 
-    elif i_tf_sc_mat == 2:
+    elif i_tf_sc_mat == SuperconductorModel.BI2212:
         # Bi-2212 high temperature superconductor parameterization
         #  Current density in a strand of Bi-2212 conductor
         #  N.B. jcrit returned by bi2212 is the critical current density
@@ -88,9 +89,9 @@ def jcrit_from_material(
         )  # bi2212 outputs j_crit_cable
         j_crit_sc = j_crit_cable / (1 - f_tf_conductor_copper)
         _tcrit = t_helium + tmarg
-    elif i_tf_sc_mat == 3:  # NbTi data
-        bc20m = 15.0
-        tc0m = 9.3
+    elif i_tf_sc_mat == SuperconductorModel.OLD_LUBELL_NBTI:  # NbTi data
+        bc20m = SuperconductorModel.OLD_LUBELL_NBTI.b_crit_zero_field_strain
+        tc0m = SuperconductorModel.OLD_LUBELL_NBTI.temp_crit_zero_field_strain
         c0 = 1.0
 
         if b_max > bc20m:
@@ -109,16 +110,18 @@ def jcrit_from_material(
         # This is needed right now. Can we change it later?
         j_crit_sc = max(1.0e-9, j_crit_sc)
         j_crit_cable = max(1.0e-9, j_crit_cable)
-    elif i_tf_sc_mat == 4:  # As (1), but user-defined parameters
+    elif (
+        i_tf_sc_mat == SuperconductorModel.USER_DEFINED_NB3SN
+    ):  # As (1), but user-defined parameters
         bc20m = b_crit_sc
         tc0m = t_crit_sc
         j_crit_sc, _bcrit, _tcrit = superconductors.itersc(
             t_helium, b_max, strain, bc20m, tc0m
         )
         j_crit_cable = j_crit_cable_from_fraction(j_crit_sc, f_tf_conductor_copper, f_he)
-    elif i_tf_sc_mat == 5:  # WST Nb3Sn parameterisation
-        bc20m = 32.97
-        tc0m = 16.06
+    elif i_tf_sc_mat == SuperconductorModel.WST_NB3SN:  # WST Nb3Sn parameterisation
+        bc20m = SuperconductorModel.WST_NB3SN.b_crit_zero_field_strain
+        tc0m = SuperconductorModel.WST_NB3SN.temp_crit_zero_field_strain
 
         #  j_crit_sc returned by itersc is the critical current density in the
         #  superconductor - not the whole strand, which contains copper
@@ -132,22 +135,33 @@ def jcrit_from_material(
         )
         j_crit_cable = j_crit_cable_from_fraction(j_crit_sc, f_tf_conductor_copper, f_he)
 
-    elif i_tf_sc_mat == 6:  # ! "REBCO" 2nd generation HTS superconductor in CroCo strand
-        j_crit_sc, _validity, _, _ = superconductors.jcrit_rebco(t_helium, b_max, 0)
+    elif (
+        i_tf_sc_mat == SuperconductorModel.CROCO_REBCO
+    ):  # ! "REBCO" 2nd generation HTS superconductor in CrCo strand
+        b_c20m = SuperconductorModel.CROCO_REBCO.b_crit_zero_field_strain
+        t_c0m = SuperconductorModel.CROCO_REBCO.temp_crit_zero_field_strain
+        j_crit_sc, _validity, _, _ = superconductors.jcrit_rebco(
+            temp_conductor=t_helium,
+            b_conductor=b_max,
+            b_c20_max=b_c20m,
+            temp_c0_max=t_c0m,
+        )
         j_crit_sc = max(1.0e-9, j_crit_sc)
         j_crit_cable = j_crit_cable_from_fraction(j_crit_sc, f_tf_conductor_copper, f_he)
 
-    elif i_tf_sc_mat == 7:  # Durham Ginzburg-Landau Nb-Ti parameterisation
-        bc20m = b_crit_upper_nbti
-        tc0m = t_crit_nbti
+    elif (
+        i_tf_sc_mat == SuperconductorModel.DURHAM_NBTI
+    ):  # Durham Ginzburg-Landau Nb-Ti parameterisation
+        bc20m = SuperconductorModel.DURHAM_NBTI.b_crit_zero_field_strain
+        tc0m = SuperconductorModel.DURHAM_NBTI.temp_crit_zero_field_strain
         j_crit_sc, _bcrit, _tcrit = superconductors.gl_nbti(
             t_helium, b_max, strain, bc20m, tc0m
         )
         j_crit_cable = j_crit_cable_from_fraction(j_crit_sc, f_tf_conductor_copper, f_he)
 
-    elif i_tf_sc_mat == 8:
-        bc20m = 429
-        tc0m = 185
+    elif i_tf_sc_mat == SuperconductorModel.DURHAM_REBCO:
+        bc20m = SuperconductorModel.DURHAM_REBCO.b_crit_zero_field_strain
+        tc0m = SuperconductorModel.DURHAM_REBCO.temp_crit_zero_field_strain
         j_crit_sc, _bcrit, _tcrit = superconductors.gl_rebco(
             t_helium, b_max, strain, bc20m, tc0m
         )
diff --git a/process/models/superconductors.py b/process/models/superconductors.py
index 2590fd9b4c..6491d59f05 100644
--- a/process/models/superconductors.py
+++ b/process/models/superconductors.py
@@ -76,49 +76,72 @@ class SuperconductorModel(IntEnum):
     ITER_NB3SN = (
         1,
         SuperconductorMaterial.NB3SN,
+        32.97e0,  # [T]
+        16.06e0,  # [K]
         SuperconductorShape.CABLE,
         "ITER Nb₃Sn critical surface model",
     )
-    BI2212 = (2, SuperconductorMaterial.BI2212, SuperconductorShape.CABLE, "Bi-2212")
+    BI2212 = (
+        2,
+        SuperconductorMaterial.BI2212,
+        None,  # Model is fitted to experimental data, so no critical B or T is defined
+        None,  # Model is fitted to experimental data, so no critical B or T is defined
+        SuperconductorShape.CABLE,
+        "Bi-2212",
+    )
     OLD_LUBELL_NBTI = (
         3,
         SuperconductorMaterial.NBTI,
+        15.0e0,  # [T]
+        9.3e0,  # [K]
         SuperconductorShape.CABLE,
         "Old Lubell NbTi",
     )
     USER_DEFINED_NB3SN = (
         4,
         SuperconductorMaterial.NB3SN,
+        None,  # User input via `bcritsc`
+        None,  # User input via `tcritsc`
         SuperconductorShape.CABLE,
         "User-defined ITER Nb₃Sn",
     )
     WST_NB3SN = (
         5,
         SuperconductorMaterial.NB3SN,
+        32.97e0,  # [T]
+        16.06e0,  # [K]
         SuperconductorShape.CABLE,
         "Western Superconducting Nb₃Sn",
     )
     CROCO_REBCO = (
         6,
         SuperconductorMaterial.REBCO,
+        132.5e0,  # [T]
+        90.0e0,  # [K]
         SuperconductorShape.TAPE,
         "CROCO REBCO",
     )
     DURHAM_NBTI = (
         7,
         SuperconductorMaterial.NBTI,
+        14.86e0,  # [T]
+        9.2e0,  # [K]
         SuperconductorShape.CABLE,
         "Durham Ginzburg-Landau NbTi",
     )
     DURHAM_REBCO = (
         8,
         SuperconductorMaterial.REBCO,
+        430.0e0,  # [T]
+        185.0e0,  # [K]
         SuperconductorShape.TAPE,
         "Durham Ginzburg-Landau REBCO",
     )
     HAZELTON_ZHAI_REBCO = (
         9,
         SuperconductorMaterial.REBCO,
+        138.0e0,  # [T]
+        92.0e0,  # [K]
         SuperconductorShape.TAPE,
         "Hazelton-Zhai REBCO",
     )
@@ -127,6 +150,8 @@ def __new__(
         cls,
         value: int,
         material: SuperconductorMaterial,
+        b_crit_zero_temp_strain: float | None,
+        temp_crit_zero_field_strain: float | None,
         shape: SuperconductorShape,
         full_name: str,
     ):
@@ -134,6 +159,8 @@ def __new__(
         obj = int.__new__(cls, value)
         obj._value_ = value
         obj._material_ = material
+        obj._b_crit_zero_temp_strain = b_crit_zero_temp_strain
+        obj._temp_crit_zero_field_strain = temp_crit_zero_field_strain
         obj._shape_ = shape
         obj._full_name_ = full_name
         return obj
@@ -153,6 +180,20 @@ def sc_shape(self):
         """The superconductor shape associated with this model."""
         return self._shape_
 
+    @DynamicClassAttribute
+    def b_crit_zero_field_strain(self):
+        """The upper critical field [T] for the superconductor at zero temperature and
+        strain (ε = 0).
+        """
+        return self._b_crit_zero_temp_strain
+
+    @DynamicClassAttribute
+    def temp_crit_zero_field_strain(self):
+        """The critical temperature [K] for the superconductor at zero field and strain
+        (ε = 0).
+        """
+        return self._temp_crit_zero_field_strain
+
     @DynamicClassAttribute
     def sc_type(self):
         """The superconductor type (LTS or HTS) associated with this model."""
@@ -165,7 +206,7 @@ def full_name(self):
 
 
 def jcrit_rebco(
-    temp_conductor: float, b_conductor: float
+    temp_conductor: float, b_conductor: float, temp_c0_max: float, b_c20_max: float
 ) -> tuple[float, bool, float, float]:
     """Calculate the critical current density for a "REBCO" 2nd generation HTS
     superconductor.
@@ -173,9 +214,13 @@ def jcrit_rebco(
     Parameters
     ----------
     temp_conductor : float
-        Superconductor temperature in Kelvin (K).
+        Superconductor temperature in Kelvin [K].
     b_conductor : float
-        Magnetic field at the superconductor in Tesla (T).
+        Magnetic field at the superconductor in Tesla [T].
+    temp_c0_max : float
+        Critical temperature [K] at zero field and strain.
+    b_c20_max : float
+        Upper critical field [T] for the superconductor at zero temperature and strain.
 
     Returns
     -------
@@ -201,11 +246,6 @@ def jcrit_rebco(
             - For temp_conductor ≥ 65 K: 0.0 T ≤ b_conductor ≤ 11.5 T
 
     """
-    # Critical temperature (K) at zero field and strain.
-    temp_c0max = 90.0
-    # Upper critical field (T) for the superconductor at zero temperature and strain.
-    b_c20max = 132.5
-
     C = 1.82962e8  # scaling constant
     p = 0.5875
     q = 1.7
@@ -233,12 +273,12 @@ def jcrit_rebco(
             b_conductor,
         )
 
-    if temp_conductor < temp_c0max:
+    if temp_conductor < temp_c0_max:
         # Normal case
-        birr = b_c20max * (1 - temp_conductor / temp_c0max) ** alpha
+        birr = b_c20_max * (1 - temp_conductor / temp_c0_max) ** alpha
     else:
         # If temp is greater than critical temp, ensure result is real but negative.
-        birr = b_c20max * (1 - temp_conductor / temp_c0max)
+        birr = b_c20_max * (1 - temp_conductor / temp_c0_max)
 
     if b_conductor < birr:
         # Normal case
@@ -248,10 +288,10 @@ def jcrit_rebco(
         # Field is too high
         # Ensure result is real but negative, and varies with temperature.
         # tcb = critical temperature at field b
-        tcb = temp_c0max * (1 - (b_conductor / b_c20max) ** oneoveralpha)
+        tcb = temp_c0_max * (1 - (b_conductor / b_c20_max) ** oneoveralpha)
         j_critical = -(temp_conductor - tcb)
 
-    return j_critical, validity, b_c20max, temp_c0max
+    return j_critical, validity, b_c20_max, temp_c0_max
 
 
 def current_sharing_rebco(bfield, j):
@@ -271,7 +311,12 @@ def current_sharing_rebco(bfield, j):
     """
 
     def deltaj_rebco(temperature):
-        jcritical, _, _, _ = jcrit_rebco(temperature, bfield)
+        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
diff --git a/process/models/tfcoil/superconducting.py b/process/models/tfcoil/superconducting.py
index 56162e2469..d212eab543 100644
--- a/process/models/tfcoil/superconducting.py
+++ b/process/models/tfcoil/superconducting.py
@@ -1228,12 +1228,23 @@ def calculate_superconductor_temperature_margin(
         #  Temperature margin (already calculated in superconductors.bi2212 for
         # i_tf_superconductor=2)
 
-        if i_tf_superconductor == 2:
+        if SuperconductorModel(i_tf_superconductor) == SuperconductorModel.BI2212:
             # Bi-2212: temperature margin already calculated elsewhere
             temp_tf_superconductor_margin = 0.0
             # Find temperature at which current density margin = 0
-        elif i_tf_superconductor in {1, 3, 4, 5, 7, 8, 9}:
-            if i_tf_superconductor == 3:
+        elif SuperconductorModel(i_tf_superconductor) in {
+            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,
@@ -2909,8 +2920,8 @@ def tf_cable_in_conduit_superconductor_properties(
         # ITER Nb3Sn critical surface parameterization
         if i_tf_superconductor == SuperconductorModel.ITER_NB3SN:
             # Peak field and temperature at zero strain
-            bc20m = 32.97e0  # [T]
-            tc0m = 16.06e0  # [K]
+            bc20m = SuperconductorModel.ITER_NB3SN.b_crit_zero_field_strain  # [T]
+            tc0m = SuperconductorModel.ITER_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:
@@ -2980,8 +2991,8 @@ def tf_cable_in_conduit_superconductor_properties(
 
         # NbTi data
         elif i_tf_superconductor == SuperconductorModel.OLD_LUBELL_NBTI:
-            bc20m = 15.0e0  # [T]
-            tc0m = 9.3e0  # [K]
+            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]
 
             j_superconductor_critical, _ = superconductors.jcrit_nbti(
@@ -3046,8 +3057,8 @@ def tf_cable_in_conduit_superconductor_properties(
 
         # WST Nb3Sn parameterisation
         elif i_tf_superconductor == SuperconductorModel.WST_NB3SN:
-            bc20m = 32.97e0  # [T]
-            tc0m = 16.06e0  # [K]
+            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:
@@ -3087,8 +3098,8 @@ def tf_cable_in_conduit_superconductor_properties(
 
         # Durham Ginzburg-Landau Nb-Ti parameterisation
         elif i_tf_superconductor == SuperconductorModel.DURHAM_NBTI:
-            bc20m = data.tfcoil.b_crit_upper_nbti  # [T]
-            tc0m = data.tfcoil.t_crit_nbti  # [K]
+            bc20m = SuperconductorModel.DURHAM_NBTI.b_crit_zero_field_strain  # [T]
+            tc0m = SuperconductorModel.DURHAM_NBTI.temp_crit_zero_field_strain  # [K]
 
             j_superconductor_critical, _, _ = superconductors.gl_nbti(
                 temp_conductor=temp_tf_coolant_peak_field,
@@ -4448,17 +4459,22 @@ def tf_croco_superconductor_properties(
         # =================================================================
 
         if i_tf_superconductor == SuperconductorModel.CROCO_REBCO:
+            b_c20_max = SuperconductorModel.CROCO_REBCO.b_crit_zero_field_strain  # [T]
+            t_c0 = SuperconductorModel.CROCO_REBCO.temp_crit_zero_field_strain  # [K]
             #  Find critical current density in superconducting cable, j_crit_cable
             j_superconductor_critical, _, bc20m, tc0m = superconductors.jcrit_rebco(
-                temp_conductor=temp_tf_peak, b_conductor=b_tf_inboard_peak
+                temp_conductor=temp_tf_peak,
+                b_conductor=b_tf_inboard_peak,
+                temp_c0_max=t_c0,
+                b_c20_max=b_c20_max,
             )
 
         # =================================================================
 
         # Durham Ginzburg-Landau critical surface model for REBCO
         elif i_tf_superconductor == SuperconductorModel.DURHAM_REBCO:
-            bc20m = 430  # [T]
-            tc0m = 185  # [K]
+            bc20m = SuperconductorModel.DURHAM_REBCO.b_crit_zero_field_strain  # [T]
+            tc0m = SuperconductorModel.DURHAM_REBCO.temp_crit_zero_field_strain  # [K]
 
             # If strain limit achieved, throw a warning and use the lower strain
             if abs(strain) > 0.7e-2:
@@ -4480,8 +4496,12 @@ def tf_croco_superconductor_properties(
 
         # Hazelton experimental data + Zhai conceptual model for REBCO
         elif i_tf_superconductor == SuperconductorModel.HAZELTON_ZHAI_REBCO:
-            bc20m = 138  # [T]
-            tc0m = 92  # [K]
+            bc20m = (
+                SuperconductorModel.HAZELTON_ZHAI_REBCO.b_crit_zero_field_strain
+            )  # [T]
+            tc0m = (
+                SuperconductorModel.HAZELTON_ZHAI_REBCO.temp_crit_zero_field_strain
+            )  # [K]
 
             # If strain limit achieved, throw a warning and use the lower strain
             if abs(strain) > 0.7e-2:
diff --git a/tests/unit/models/test_pfcoil.py b/tests/unit/models/test_pfcoil.py
index dc096cb36d..a7b8c4fe64 100644
--- a/tests/unit/models/test_pfcoil.py
+++ b/tests/unit/models/test_pfcoil.py
@@ -2478,8 +2478,6 @@ class PFCoilParam(NamedTuple):
     tcritsc: Any = None
     str_pf_con_res: Any = None
     bcritsc: Any = None
-    b_crit_upper_nbti: Any = None
-    t_crit_nbti: Any = None
     first_call: Any = None
     r_tf_outboard_out: Any = None
     t_plant_pulse_coil_precharge: Any = None
@@ -2553,8 +2551,6 @@ class PFCoilParam(NamedTuple):
             tcritsc=1.6e1,
             str_pf_con_res=-5.0e-3,
             bcritsc=2.4e1,
-            b_crit_upper_nbti=1.486e1,
-            t_crit_nbti=9.04,
             first_call=True,
             r_tf_outboard_out=10.0,
             t_plant_pulse_coil_precharge=5.0e2,
@@ -2661,8 +2657,6 @@ def test_pfcoil(monkeypatch, pfcoil, pfcoilparam):
         "tcritsc",
         "str_pf_con_res",
         "bcritsc",
-        "b_crit_upper_nbti",
-        "t_crit_nbti",
     ]:
         monkeypatch.setattr(pfcoil.data.tfcoil, field, getattr(pfcoilparam, field))
 
@@ -2727,14 +2721,12 @@ class OhCalcParam(NamedTuple):
     str_cs_con_res: Any = None
     fhts: Any = None
     bcritsc: Any = None
-    t_crit_nbti: Any = None
     c_pf_cs_coil_pulse_start_ma: Any = None
     c_pf_cs_coil_flat_top_ma: Any = None
     c_pf_cs_coil_pulse_end_ma: Any = None
     rmajor: Any = None
     plasma_current: Any = None
     poisson_steel: Any = None
-    b_crit_upper_nbti: Any = None
     exp_b_pf_coil_peak: Any = None
     exp_j_cs_critical_flat_top_end: Any = None
 
@@ -2780,14 +2772,12 @@ class OhCalcParam(NamedTuple):
             str_cs_con_res=-5.000e-3,
             fhts=0.5,
             bcritsc=2.4e1,
-            t_crit_nbti=9.04,
             c_pf_cs_coil_pulse_start_ma=np.full(22, 0.0),
             c_pf_cs_coil_flat_top_ma=np.full(22, 0.0),
             c_pf_cs_coil_pulse_end_ma=np.full(22, -175.84911993600002),
             rmajor=8.938,
             plasma_current=1.8254e7,
             poisson_steel=3.0e-1,
-            b_crit_upper_nbti=9.04,
             exp_b_pf_coil_peak=13.073958753751993,
             exp_j_cs_critical_flat_top_end=54101481.7685945,
         )
@@ -2854,9 +2844,7 @@ def test_ohcalc(monkeypatch, reinitialise_error_module, cs_coil, ohcalcparam):
         "str_cs_con_res",
         "fhts",
         "bcritsc",
-        "t_crit_nbti",
         "poisson_steel",
-        "b_crit_upper_nbti",
     ]:
         monkeypatch.setattr(cs_coil.data.tfcoil, field, getattr(ohcalcparam, field))
 
@@ -3805,8 +3793,6 @@ def test_peakb(monkeypatch, pfcoil):
 
 
 class SuperconPFParam(NamedTuple):
-    b_crit_upper_nbti: Any = None
-    t_crit_nbti: Any = None
     bmax: Any = None
     fhe: Any = None
     fcu: Any = None
@@ -3836,8 +3822,6 @@ class SuperconPFParam(NamedTuple):
             thelium=4.75,
             bcritsc=24,
             tcritsc=16,
-            b_crit_upper_nbti=14.86,
-            t_crit_nbti=9.04,
             dr_tf_hts_tape=4.0e-3,
             dx_tf_hts_tape_rebco=1.0e-6,
             dx_tf_hts_tape_total=6.5e-5,
@@ -3873,8 +3857,6 @@ def test_superconpf(superconpfparam):
         superconpfparam.thelium,
         superconpfparam.bcritsc,
         superconpfparam.tcritsc,
-        superconpfparam.b_crit_upper_nbti,
-        superconpfparam.t_crit_nbti,
         superconpfparam.dr_tf_hts_tape,
         superconpfparam.dx_tf_hts_tape_rebco,
         superconpfparam.dx_tf_hts_tape_total,
diff --git a/tests/unit/models/test_superconductors.py b/tests/unit/models/test_superconductors.py
index f6626623e4..393ec37e98 100644
--- a/tests/unit/models/test_superconductors.py
+++ b/tests/unit/models/test_superconductors.py
@@ -3,7 +3,7 @@
 import pytest
 
 from process.models import superconductors
-from process.models.superconductors import CroCoCableGeometry
+from process.models.superconductors import CroCoCableGeometry, SuperconductorModel
 
 
 class IterscParam(NamedTuple):
@@ -31,8 +31,8 @@ class IterscParam(NamedTuple):
             thelium=4.75,
             bmax=13.008974843466492,
             strain=0.001601605753441172,
-            bc20max=32.969999999999999,
-            tc0max=16.059999999999999,
+            bc20max=SuperconductorModel.ITER_NB3SN.b_crit_zero_field_strain,
+            tc0max=SuperconductorModel.ITER_NB3SN.temp_crit_zero_field_strain,
             expected_jcrit=692348194.774593,
             expected_bcrit=27.092853296363597,
             expected_tcrit=11.338458919718571,
@@ -41,8 +41,8 @@ class IterscParam(NamedTuple):
             thelium=6.2510000000000003,
             bmax=13.008974843466492,
             strain=0.001601605753441172,
-            bc20max=32.969999999999999,
-            tc0max=16.059999999999999,
+            bc20max=SuperconductorModel.ITER_NB3SN.b_crit_zero_field_strain,
+            tc0max=SuperconductorModel.ITER_NB3SN.temp_crit_zero_field_strain,
             expected_jcrit=495889332.08959526,
             expected_bcrit=24.442648486388464,
             expected_tcrit=11.338458919718571,
@@ -101,8 +101,8 @@ class JcritNbtiParam(NamedTuple):
             temperature=4.75,
             bmax=8.0517923638507547,
             c0=10000000000,
-            bc20max=15,
-            tc0max=9.3000000000000007,
+            bc20max=SuperconductorModel.OLD_LUBELL_NBTI.b_crit_zero_field_strain,
+            tc0max=SuperconductorModel.OLD_LUBELL_NBTI.temp_crit_zero_field_strain,
             expected_jcrit=906668274.04561484,
             expected_tcrit=5.9060082696285683,
         ),
@@ -110,8 +110,8 @@ class JcritNbtiParam(NamedTuple):
             temperature=6,
             bmax=8.0517923638507547,
             c0=10000000000,
-            bc20max=15,
-            tc0max=9.3000000000000007,
+            bc20max=SuperconductorModel.OLD_LUBELL_NBTI.b_crit_zero_field_strain,
+            tc0max=SuperconductorModel.OLD_LUBELL_NBTI.temp_crit_zero_field_strain,
             expected_jcrit=-73718607.547511846,
             expected_tcrit=5.9060082696285683,
         ),
@@ -143,7 +143,12 @@ def test_jcrit_nbti(jcritnbtiparam):
 
 
 def test_jcrit_rebco():
-    jcrit_rebco, validity, _, _ = superconductors.jcrit_rebco(4.75, 7.0)
+    jcrit_rebco, validity, _, _ = superconductors.jcrit_rebco(
+        temp_conductor=4.75,
+        b_conductor=7.0,
+        temp_c0_max=SuperconductorModel.CROCO_REBCO.temp_crit_zero_field_strain,
+        b_c20_max=SuperconductorModel.CROCO_REBCO.b_crit_zero_field_strain,
+    )
 
     assert jcrit_rebco == pytest.approx(55870234414.171684)
     assert validity
diff --git a/tests/unit/models/tfcoil/test_sctfcoil.py b/tests/unit/models/tfcoil/test_sctfcoil.py
index 71fbafe4a9..5dd134b05f 100644
--- a/tests/unit/models/tfcoil/test_sctfcoil.py
+++ b/tests/unit/models/tfcoil/test_sctfcoil.py
@@ -3,6 +3,7 @@
 import numpy as np
 import pytest
 
+from process.models.superconductors import SuperconductorModel
 from process.models.tfcoil import superconducting as sctf
 
 
@@ -161,14 +162,10 @@ class SuperconParam(NamedTuple):
 
     a_tf_turn_cable_space_effective: Any = None
 
-    b_crit_upper_nbti: Any = None
-
     i_str_wp: Any = None
 
     str_wp: Any = None
 
-    t_crit_nbti: Any = None
-
     tf_fit_t: Any = None
 
     tf_fit_z: Any = None
@@ -249,15 +246,13 @@ class SuperconParam(NamedTuple):
             c_tf_turn=74026.751437500003,
             b_tf_inboard_peak_with_ripple=12.48976756562082,
             str_tf_con_res=-0.0050000000000000001,
-            b_crit_upper_nbti=14.859999999999999,
             i_str_wp=1,
             f_a_tf_turn_cable_space_cooling=0.3,
             str_wp=0.0015619754370069119,
-            t_crit_nbti=9.0399999999999991,
             tf_fit_t=0.80807838916035957,
             tf_fit_z=0.3149613642807837,
             f_b_tf_inboard_peak_ripple_symmetric=1.0658869305062604,
-            i_tf_superconductor=5,
+            i_tf_superconductor=SuperconductorModel.WST_NB3SN,
             iprint=0,
             outfile=11,
             a_tf_turn_cable_space=0.001293323051622732,
@@ -286,8 +281,8 @@ class SuperconParam(NamedTuple):
             expected_j_superconductor_critical=832616175.5329928,
             expected_f_c_tf_turn_operating_critical=0.46510052068203006,
             expected_j_tf_coil_turn=23124470.793774802,
-            expected_bc20m=32.97,
-            expected_tc0m=16.06,
+            expected_bc20m=SuperconductorModel.WST_NB3SN.b_crit_zero_field_strain,
+            expected_tc0m=SuperconductorModel.WST_NB3SN.temp_crit_zero_field_strain,
             expected_c_turn_cables_critical=159162.9081148869,
             expected_j_superconductor=387250216.7686755,
         ),
@@ -299,15 +294,13 @@ class SuperconParam(NamedTuple):
             c_tf_turn=74026.751437500003,
             b_tf_inboard_peak_with_ripple=12.48976756562082,
             str_tf_con_res=-0.0050000000000000001,
-            b_crit_upper_nbti=14.859999999999999,
             i_str_wp=1,
             f_a_tf_turn_cable_space_cooling=0.3,
             str_wp=0.0015619754370069119,
-            t_crit_nbti=9.0399999999999991,
             tf_fit_t=0.80807838916035957,
             tf_fit_z=0.3149613642807837,
             f_b_tf_inboard_peak_ripple_symmetric=1.0658869305062604,
-            i_tf_superconductor=5,
+            i_tf_superconductor=SuperconductorModel.WST_NB3SN,
             iprint=0,
             outfile=11,
             a_tf_turn_cable_space=0.001293323051622732,
@@ -334,8 +327,8 @@ class SuperconParam(NamedTuple):
             expected_j_superconductor_critical=832616175.5329928,
             expected_f_c_tf_turn_operating_critical=0.46510052068203006,
             expected_j_tf_coil_turn=23124470.793774802,
-            expected_bc20m=32.97,
-            expected_tc0m=16.06,
+            expected_bc20m=SuperconductorModel.WST_NB3SN.b_crit_zero_field_strain,
+            expected_tc0m=SuperconductorModel.WST_NB3SN.temp_crit_zero_field_strain,
             expected_c_turn_cables_critical=159162.9081148869,
             expected_j_superconductor=387250216.7686755,
         ),
@@ -400,18 +393,10 @@ def test_supercon(superconparam, monkeypatch, cicc_sctfcoil):
         cicc_sctfcoil.data.tfcoil, "str_tf_con_res", superconparam.str_tf_con_res
     )
 
-    monkeypatch.setattr(
-        cicc_sctfcoil.data.tfcoil, "b_crit_upper_nbti", superconparam.b_crit_upper_nbti
-    )
-
     monkeypatch.setattr(cicc_sctfcoil.data.tfcoil, "i_str_wp", superconparam.i_str_wp)
 
     monkeypatch.setattr(cicc_sctfcoil.data.tfcoil, "str_wp", superconparam.str_wp)
 
-    monkeypatch.setattr(
-        cicc_sctfcoil.data.tfcoil, "t_crit_nbti", superconparam.t_crit_nbti
-    )
-
     monkeypatch.setattr(
         cicc_sctfcoil.data.superconducting_tfcoil, "tf_fit_t", superconparam.tf_fit_t
     )
@@ -2051,19 +2036,79 @@ def test_superconducting_tf_coil_area_and_masses(
     ),
     [
         # ITER Nb3Sn, standard parameters
-        (1, 1e8, 12.0, 0.0, 32.97, 16.06, 1e10, 4.5, 5.679499736095401),
+        (
+            1,
+            1e8,
+            12.0,
+            0.0,
+            SuperconductorModel.ITER_NB3SN.b_crit_zero_field_strain,
+            SuperconductorModel.ITER_NB3SN.temp_crit_zero_field_strain,
+            1e10,
+            4.5,
+            5.679499736095401,
+        ),
         # NbTi
-        (3, 1e8, 8.0, 0.0, 15.0, 9.3, 1e10, 4.5, 1.3048296694055175),
+        (
+            3,
+            1e8,
+            8.0,
+            0.0,
+            SuperconductorModel.OLD_LUBELL_NBTI.b_crit_zero_field_strain,
+            SuperconductorModel.OLD_LUBELL_NBTI.temp_crit_zero_field_strain,
+            1e10,
+            4.5,
+            1.3048296694055175,
+        ),
         # User-defined Nb3Sn
         (4, 1e8, 10.0, 0.0, 30.0, 15.0, 1e10, 4.5, 5.539631803535094),
         # WST Nb3Sn
-        (5, 1e8, 13.0, 0.0, 32.97, 16.06, 1e10, 4.5, 5.221287311831414),
+        (
+            5,
+            1e8,
+            13.0,
+            0.0,
+            SuperconductorModel.WST_NB3SN.b_crit_zero_field_strain,
+            SuperconductorModel.WST_NB3SN.temp_crit_zero_field_strain,
+            1e10,
+            4.5,
+            5.221287311831414,
+        ),
         # Durham Ginzburg-Landau Nb-Ti
-        (7, 1e8, 7.0, 0.0, 14.85, 9.04, 1e10, 4.5, 1.263064155425198),
+        (
+            7,
+            1e8,
+            7.0,
+            0.0,
+            SuperconductorModel.DURHAM_NBTI.b_crit_zero_field_strain,
+            SuperconductorModel.DURHAM_NBTI.temp_crit_zero_field_strain,
+            1e10,
+            4.5,
+            1.3679852289396255,
+        ),
         # Durham Ginzburg-Landau REBCO
-        (8, 1e8, 10.0, 0.0, 430, 185, 1e10, 20.0, 31.82616792800119),
+        (
+            8,
+            1e8,
+            10.0,
+            0.0,
+            SuperconductorModel.DURHAM_REBCO.b_crit_zero_field_strain,
+            SuperconductorModel.DURHAM_REBCO.temp_crit_zero_field_strain,
+            1e10,
+            20.0,
+            31.82616792800119,
+        ),
         # Hazelton-Zhai REBCO
-        (9, 1e8, 10.0, 0.0, 138, 92, 1e10, 20.0, 48.363687012510425),
+        (
+            9,
+            1e8,
+            10.0,
+            0.0,
+            SuperconductorModel.HAZELTON_ZHAI_REBCO.b_crit_zero_field_strain,
+            SuperconductorModel.HAZELTON_ZHAI_REBCO.temp_crit_zero_field_strain,
+            1e10,
+            20.0,
+            48.363687012510425,
+        ),
     ],
 )
 def test_calculate_superconductor_temperature_margin(