Gamma contact dose rate computation fispact style

openmc/data/__init__.py

@@ -35,3 +35,4 @@
 from .function import *
 
 from .effective_dose.dose import dose_coefficients
+from .mass_energy_absorption import mu_en_coefficients

openmc/data/data.py

@@ -274,6 +274,7 @@
 # Unit conversions
 EV_PER_MEV = 1.0e6
 JOULE_PER_EV = 1.602176634e-19
+BARN_PER_CM_SQ = 1.0e24
 
 # Avogadro's constant
 AVOGADRO = 6.02214076e23

openmc/data/mass_energy_absorption.py

@@ -0,0 +1,93 @@
+import numpy as np
+
+import openmc.checkvalue as cv
+from openmc.data import EV_PER_MEV
+
+# Embedded NIST-126 data
+# Air (Dry Near Sea Level) — NIST Standard Reference Database 126 Table 4 (doi: 10.18434/T4D01F)
+# Columns: Energy (MeV), μen/ρ (cm^2/g)
+_NIST126_AIR = np.array(
+    [
+        [1.00000e-03, 3.599e03],
+        [1.50000e-03, 1.188e03],
+        [2.00000e-03, 5.262e02],
+        [3.00000e-03, 1.614e02],
+        [3.20290e-03, 1.330e02],
+        [3.20290e-03, 1.460e02],
+        [4.00000e-03, 7.636e01],
+        [5.00000e-03, 3.931e01],
+        [6.00000e-03, 2.270e01],
+        [8.00000e-03, 9.446e00],
+        [1.00000e-02, 4.742e00],
+        [1.50000e-02, 1.334e00],
+        [2.00000e-02, 5.389e-01],
+        [3.00000e-02, 1.537e-01],
+        [4.00000e-02, 6.833e-02],
+        [5.00000e-02, 4.098e-02],
+        [6.00000e-02, 3.041e-02],
+        [8.00000e-02, 2.407e-02],
+        [1.00000e-01, 2.325e-02],
+        [1.50000e-01, 2.496e-02],
+        [2.00000e-01, 2.672e-02],
+        [3.00000e-01, 2.872e-02],
+        [4.00000e-01, 2.949e-02],
+        [5.00000e-01, 2.966e-02],
+        [6.00000e-01, 2.953e-02],
+        [8.00000e-01, 2.882e-02],
+        [1.00000e00, 2.789e-02],
+        [1.25000e00, 2.666e-02],
+        [1.50000e00, 2.547e-02],
+        [2.00000e00, 2.345e-02],
+        [3.00000e00, 2.057e-02],
+        [4.00000e00, 1.870e-02],
+        [5.00000e00, 1.740e-02],
+        [6.00000e00, 1.647e-02],
+        [8.00000e00, 1.525e-02],
+        [1.00000e01, 1.450e-02],
+        [1.50000e01, 1.353e-02],
+        [2.00000e01, 1.311e-02],
+    ],
+    dtype=float,
+)
+
+# Registry of embedded tables: (data_source, material) -> ndarray
+# Table shape: (N, 2) with columns [Energy (MeV), μen/ρ (cm^2/g)]
+_MUEN_TABLES = {
+    ("nist126", "air"): _NIST126_AIR,
+}
+
+
+def mu_en_coefficients(
+    material: str, data_source: str = "nist126"
+) -> tuple[np.ndarray, np.ndarray]:
+    """Return tabulated mass energy-absorption coefficients.
+
+    Parameters
+    ----------
+    material : {'air'}
+        Material compound for which to load coefficients.
+    data_source : {'nist126'}
+        Source library.
+
+    Returns
+    -------
+    energy : numpy.ndarray
+        Energies [eV]
+    mu_en_coeffs : numpy.ndarray
+        Mass energy-absorption coefficients [cm^2/g]
+    """
+    cv.check_value("material", material, {"air"})
+    cv.check_value("data_source", data_source, {"nist126"})
+
+    key = (data_source, material)
+    if key not in _MUEN_TABLES:
+        available = sorted({m for (ds, m) in _MUEN_TABLES.keys() if ds == data_source})
+        raise ValueError(
+            f"'{material}' has no embedded μen/ρ table for data source {data_source}. "
+            f"Available materials for {data_source}: {available}"
+        )
+
+    data = _MUEN_TABLES[key]
+    energy = data[:, 0].copy() * EV_PER_MEV  # MeV -> eV
+    mu_en_coeffs = data[:, 1].copy()
+    return energy, mu_en_coeffs

openmc/data/photon_attenuation.py

@@ -0,0 +1,80 @@
+import numpy as np
+
+from openmc.exceptions import DataError
+
+from .data import ATOMIC_SYMBOL, ELEMENT_SYMBOL, zam
+from .function import Sum, Tabulated1D
+from .library import DataLibrary
+from .photon import IncidentPhoton
+
+
+_PHOTON_LIB: DataLibrary | None = None
+_PHOTON_DATA: dict[str, IncidentPhoton] = {}
+
+
+def _get_photon_data(nuclide: str) -> IncidentPhoton | None:
+    global _PHOTON_LIB
+
+    if _PHOTON_LIB is None:
+        try:
+            _PHOTON_LIB = DataLibrary.from_xml()
+        except Exception as err:
+            raise DataError(
+                "A cross section library must be specified with "
+                "openmc.config['cross_sections'] in order to load photon data."
+            ) from err
+
+    lib = _PHOTON_LIB.get_by_material(nuclide, data_type="photon")
+    if lib is None:
+        return None
+
+    if nuclide not in _PHOTON_DATA:
+        _PHOTON_DATA[nuclide] = IncidentPhoton.from_hdf5(lib["path"])
+
+    return _PHOTON_DATA[nuclide]
+
+
+def linear_attenuation_xs(element_input: str) -> Sum | None:
+    """Return total photon interaction cross section for a nuclide.
+
+    Parameters
+    ----------
+    element_input : str
+        Name of nuclide or element
+
+    Returns
+    -------
+    openmc.data.Sum or None
+        Sum of the relevant photon reaction cross sections as a function of
+        photon energy, or None if no photon data exist for *nuclide*.
+    """
+
+    try:
+        z = zam(element_input)[0]
+        element = ATOMIC_SYMBOL[z]
+    except (ValueError, KeyError, TypeError):
+        if element_input not in ELEMENT_SYMBOL.values():
+            raise ValueError(f"Element '{element_input}' not found in ELEMENT_SYMBOL.")
+        element = element_input
+
+    photon_data = _get_photon_data(element)
+    if photon_data is None:
+        return None
+
+    photon_mts = (502, 504, 515, 517, 522)
+
+    xs_list = []
+    for reaction in photon_data.reactions.values():
+        mt = getattr(reaction, "mt", None)
+        if mt not in photon_mts:
+            continue
+
+        xs_list.append(reaction.xs)
+
+    if not xs_list:
+        return None
+
+    return Sum(xs_list)
+
+
+