def get_emission_coef(df_coef):
    """
    Overwrite emissions coefficients for nuclear generators

    Parameters
    ----------
    df_coef: DataFrame
        Coefficients dataframe with fuel and cooling systems assigned

    Returns
    -------
    df_coef: DataFrame
        Updated coefficients dataframe with nuclear emission coefficients
        adjusted
    """
    # Local vars
    emit_cols = ['alpha', 'beta_emit', 'gamma', 'xi', 'lambda']

    # Nuclear has no air pollution
    nuc_idx = df_coef[df_coef['fuel_type'] == 'Nuclear'].index
    df_coef.loc[nuc_idx, emit_cols] = 0.0

    return df_coef