def METHOD_NAME(self):
    # Read the statepoint and summary files.
    statepoint = glob.glob(os.path.join(os.getcwd(), self._sp_name))[0]
    sp = openmc.StatePoint(statepoint)
    # Extract the tally data as a Pandas DataFrame.
    tally_dfs = [t.get_pandas_dataframe() for t in sp.tallies.values()]
    df = pd.concat(tally_dfs, ignore_index=True)
    # Extract the relevant data as a CSV string.
    cols = ('d_material', 'd_nuclide', 'd_variable', 'score', 'mean',
            'std. dev.')
    return df.to_csv(None, columns=cols, index=False, float_format='%.7e')