Plot neutron reaction threshold energy for an isotopes. Setup to show different reactions resulting from DD (~2.5MeV) and DT (~14.1MeV) neutron sources.

neutron_reaction_threshold_plot

import matplotlib.pyplot as plt
import openmc
from matplotlib.lines import Line2D


def plot_thresholds(nuclide="Fe56"):
    plt.clf()
    threshold_below_14 = 0
    threshold_below_2 = 0
    x = {}
    fe = openmc.data.IncidentNeutron.from_hdf5(
        # this dir would need changing to read the local nuclear data
        f"/home/jshimwell/ENDF-B-VIII.0-NNDC/h5_files/neutron/{nuclide}.h5"
    )
    for key, value in fe.reactions.items():
        reaction = fe[key]
        xs = reaction.xs["294K"]
        threshold = xs.x[0]
        name = reaction.__str__().split()[-1][:-1]
        if name not in ["heating", "damage-energy", "heating-local"]:
            # print(threshold/1e6, name)
            x[name] = threshold
            if threshold < 14.1e6:
                threshold_below_14 = threshold_below_14 + 1
                color = "blue"
                plt.plot(xs.x / 1e6, xs.y, label=name, color=color, linewidth=0.5)
            if threshold < 2.5e6:
                threshold_below_2 = threshold_below_2 + 1
                color = "red"
                plt.plot(xs.x / 1e6, xs.y, label=name, color=color, linewidth=0.5)
            print(key, name, threshold / 1e6)

    custom_lines = [
        Line2D([0], [0], color="red", lw=4),
        Line2D([0], [0], color="blue", lw=4),
    ]
    plt.legend(
        custom_lines,
        ["Reaction threshold < 2.5MeV", "Reaction threshold > 2.5 MeV and < 14 MeV"],
    )
    plt.title(
        f"Neutron reaction cross sections for {nuclide} colored by threshold energy.\n {threshold_below_2} reactions below 2.5MeV {threshold_below_14} reactions below 14.1MeV"
    )
    plt.yscale("log")
    plt.xlabel("Energy [MeV]")
    plt.ylabel("Cross sections [barns]")

    plt.xlim((0, 15))
    plt.ylim((1e-16, 1e10))
    plt.savefig(f"threshold_{nuclide}.png", dpi=200)

    # all the reactiosn sorted by energy
    all = dict(sorted(x.items(), key=lambda item: item[1]))


plot_thresholds(nuclide="Al27")
plot_thresholds(nuclide="Fe56")

Example plots show there are many more reactions from DT neutron sources compared to DD neutron sources