Add AvailabilityModel enum for plant availability models

process/core/scan.py

@@ -17,6 +17,7 @@
 from process.core.solver.solver_handler import SolverHandler
 from process.data_structure.numerics import FiguresOfMerit, PROCESSRunMode
 from process.data_structure.scan_variables import IPNSCNS, NOUTVARS, ScanData
+from process.models.availability import AvailabilityModel
 
 if TYPE_CHECKING:
     from process.core.model import DataStructure, Model
@@ -1145,7 +1146,10 @@ def scan_select(self, nwp, swp, iscn):
             case 20:
                 self.data.constraints.t_burn_min = swp[iscn - 1]
             case 22:
-                if self.data.costs.i_plant_availability == 1:
+                if (
+                    AvailabilityModel(self.data.costs.i_plant_availability)
+                    != AvailabilityModel.USER_INPUT
+                ):
                     raise ProcessValueError(
                         "Do not scan f_t_plant_available if i_plant_availability=1"
                     )

process/core/solver/objectives.py

@@ -3,6 +3,7 @@
 from process.core.exceptions import ProcessValueError
 from process.core.model import DataStructure
 from process.data_structure.numerics import FiguresOfMerit
+from process.models.availability import AvailabilityModel
 
 
 def objective_function(minmax: int, data: DataStructure) -> float:
@@ -70,8 +71,14 @@ def objective_function(minmax: int, data: DataStructure) -> float:
     elif figure_of_merit == FiguresOfMerit.PULSE_LENGTH:
         objective_metric = data.times.t_plant_pulse_burn / 2.0e4
     elif figure_of_merit == FiguresOfMerit.PLANT_AVAILABILITY_FACTOR:
-        if data.costs.i_plant_availability != 1:
-            raise ProcessValueError("minmax=15 requires i_plant_availability=1")
+        if (
+            AvailabilityModel(data.costs.i_plant_availability)
+            == AvailabilityModel.USER_INPUT
+        ):
+            raise ProcessValueError(
+                "minmax=15 requires `f_t_plant_available` to be calculated, not user "
+                "input"
+            )
         objective_metric = data.costs.f_t_plant_available
     elif figure_of_merit == FiguresOfMerit.MIN_R0_MAX_TAU_BURN:
         objective_metric = 0.95 * (data.physics.rmajor / 9.0) - 0.05 * (

process/models/availability.py

@@ -1,5 +1,7 @@
 import logging
 import math
+from enum import IntEnum
+from types import DynamicClassAttribute
 
 from scipy.special import comb as combinations
 
@@ -11,6 +13,41 @@
 
 logger = logging.getLogger(__name__)
 
+
+class AvailabilityModel(IntEnum):
+    """Enum for availability models"""
+
+    USER_INPUT = (0, "Input value for `f_t_plant_available`")
+    WARD_TAYLOR = (1, "Ward and Taylor model (1999)")
+    MORRIS = (2, "Morris model (2015)")
+    ST = (3, "ST model (2023)")
+
+    def __new__(cls, value: int, full_name: str):
+        """Create a new AvailabilityModel enum instance.
+
+        Parameters
+        ----------
+        value : int
+            The integer value of the enum member.
+        full_name : str
+            The full name/description of the availability model.
+
+        Returns
+        -------
+        AvailabilityModel
+            A new enum instance with the specified value and full_name.
+        """
+        obj = int.__new__(cls, value)
+        obj._value_ = value
+        obj._full_name_ = full_name
+        return obj
+
+    @DynamicClassAttribute
+    def full_name(self):
+        """The full name of the availability model."""
+        return self._full_name_
+
+
 DAY_SECONDS = 60 * 60 * 24
 # Number of seconds in a day [s]
 
@@ -20,13 +57,6 @@
 YEAR_SECONDS = DAY_SECONDS * DAYS_IN_YEAR
 # Number of seconds in a year [s]
 
-AVAILABILITY_MODELS = {
-    0: "Input value for f_t_plant_available",
-    1: "Ward and Taylor model (1999)",
-    2: "Morris model (2015)",
-    3: "ST model (2023)",
-}
-
 
 class Availability(Model):
     """Module containing plant availability routines
@@ -58,15 +88,21 @@ def run(self, output: bool = False):
         output :
             indicate whether output should be written to the output file, or not
         """
-        if self.data.costs.i_plant_availability == 3:
+        if (
+            AvailabilityModel(self.data.costs.i_plant_availability)
+            == AvailabilityModel.ST
+        ):
             if self.data.physics.itart != 1:
                 raise ProcessValueError(
                     f"{self.data.costs.i_plant_availability=}"
                     " is for a Spherical Tokamak."
                     " Please set itart=1 to use this model."
                 )
             self.avail_st(output)  # ST model (2023)
-        elif self.data.costs.i_plant_availability == 2:
+        elif (
+            AvailabilityModel(self.data.costs.i_plant_availability)
+            == AvailabilityModel.MORRIS
+        ):
             self.avail_2(output)  # Morris model (2015)
         else:
             self.avail(output)  # Taylor and Ward model (1999)
@@ -167,7 +203,10 @@ def avail(self, output: bool):
         # if i_plant_availability = 0 use input value for f_t_plant_available
 
         # Taylor and Ward 1999 model (i_plant_availability=1)
-        if self.data.costs.i_plant_availability == 1:
+        if (
+            AvailabilityModel(self.data.costs.i_plant_availability)
+            == AvailabilityModel.WARD_TAYLOR
+        ):
             # Which component has the shorter life?
             if self.data.costs.life_div_fpy < self.data.fwbs.life_blkt_fpy:
                 ld = self.data.costs.life_div_fpy
@@ -294,7 +333,10 @@ def avail(self, output: bool):
                 self.data.costs.life_plant,
             )
 
-            if self.data.costs.i_plant_availability == 1:
+            if (
+                AvailabilityModel(self.data.costs.i_plant_availability)
+                == AvailabilityModel.WARD_TAYLOR
+            ):
                 if self.data.costs.life_div_fpy < self.data.fwbs.life_blkt_fpy:
                     po.ovarre(
                         self.outfile,
@@ -331,7 +373,10 @@ def avail(self, output: bool):
                     "OP ",
                 )
 
-            if self.data.costs.i_plant_availability == 0:
+            if (
+                AvailabilityModel(self.data.costs.i_plant_availability)
+                == AvailabilityModel.USER_INPUT
+            ):
                 po.ovarre(
                     self.outfile,
                     "Total plant availability fraction",