diff --git a/docs/source/io_formats/fission_energy.rst b/docs/source/io_formats/fission_energy.rst new file mode 100644 index 000000000..d73a95f60 --- /dev/null +++ b/docs/source/io_formats/fission_energy.rst @@ -0,0 +1,53 @@ +.. _usersguide_fission_energy: + +================================== +Fission Energy Release File Format +================================== + +This file is a compact HDF5 representation of the ENDF MT=1, MF=458 data (see +ENDF-102_ for details). It gives the information needed to compute the energy +carried away from fission reactions by each reaction product (e.g. fragment +nuclei, neutrons) which depends on the incident neutron energy. OpenMC is +distributed with one of these files under +openmc/data/fission_Q_data_endfb71.h5. More files of this format can be +created from ENDF files with the +``openmc.data.write_compact_458_library`` function. They can be read with the +``openmc.data.FissionEnergyRelease.from_compact_hdf5`` class method. + +:Attributes: - **comment** (*char[]*) -- An optional text comment + - **component order** (*char[][]*) -- An array of strings + specifying the order each reaction product occurs in the data + arrays. The components use the 2-3 letter abbreviations + specified in ENDF-102 e.g. EFR for fission fragments and ENP for + prompt neutrons. + +**//** + Nuclides are named by concatenating their Z and their A numbers. For + example, U235 is named 92235. Metastable nuclides are appended with an + '_m' and their metastable number. For example, the first excited isomer + of Am-242 is named 95242_m1. + +:Datasets: - **data** (*double[][][]*) -- The energy release coefficients. The + first axis indexes the component type. The second axis specifies + values or uncertainties. The third axis indexes the polynomial + order. If the data uses the Sher-Beck format, then the last axis + will have a length of one and ENDF-102 should be consulted for + energy dependence. Otherwise, the data uses the Madland format + which is a polynomial of incident energy. + + For example, if 'EFR' is given first in the **component order** + attribute and the data uses the Madland format, then the energy + released in the form of fission fragments at an incident energy + :math:`E` is given by + + .. math:: + \text{data}[0, 0, 0] + \text{data}[0, 0, 1] \cdot E + + \text{data}[0, 0, 2] \cdot E^2 + \ldots + + And its uncertainty is + + .. math:: + \text{data}[0, 1, 0] + \text{data}[0, 1, 1] \cdot E + + \text{data}[0, 1, 2] \cdot E^2 + \ldots + +.. _ENDF-102: http://www.nndc.bnl.gov/endfdocs/ENDF-102-2012.pdf diff --git a/docs/source/io_formats/index.rst b/docs/source/io_formats/index.rst index acab7e893..39b38fcf2 100644 --- a/docs/source/io_formats/index.rst +++ b/docs/source/io_formats/index.rst @@ -15,6 +15,7 @@ Data Files nuclear_data mgxs_library data_wmp + fission_energy ------------ Output Files diff --git a/docs/source/io_formats/nuclear_data.rst b/docs/source/io_formats/nuclear_data.rst index ba6a54eb1..7544ca1f5 100644 --- a/docs/source/io_formats/nuclear_data.rst +++ b/docs/source/io_formats/nuclear_data.rst @@ -55,6 +55,27 @@ Incident Neutron Data from fission. It is formatted as a reaction product, described in :ref:`product`. +**//fission_energy_release/** + +:Attributes: - **format** (*char[]*) -- The energy-dependence format. Either + 'Madland' or 'Sher-Beck' + +:Datasets: - **fragments** (*double[]*) -- Polynomial coefficients for energy + released in the form of fragments + - **prompt_neutrons** (*double[]* or :ref:`tabulated <1d_tabulated>`) + -- Energy released in the form of prompt neutrons. Polynomial if + the format is Madland or a table if Sher-Beck. + - **delayed_neutrons** (*double[]*) -- Polynomial coefficients for + energy released in the form of delayed neutrons + - **prompt_photons** (*double[]*) -- Polynomial coefficients for + energy released in the form of prompt photons + - **delayed_photons** (*double[]*) -- Polynomial coefficients for + energy released in the form of delayed photons + - **betas** (*double[]*) -- Polynomial coefficients for + energy released in the form of betas + - **neutrinos** (*double[]*) -- Polynomial coefficients for + energy released in the form of neutrinos + ------------------------------- Thermal Neutron Scattering Data ------------------------------- diff --git a/docs/source/pythonapi/index.rst b/docs/source/pythonapi/index.rst index 36f161b3c..5d45c799d 100644 --- a/docs/source/pythonapi/index.rst +++ b/docs/source/pythonapi/index.rst @@ -335,6 +335,7 @@ Core Classes openmc.data.Tabulated1D openmc.data.ThermalScattering openmc.data.CoherentElastic + openmc.data.FissionEnergyRelease Angle-Energy Distributions -------------------------- @@ -368,21 +369,22 @@ Classes +++++++ .. autosummary:: - :toctree: generated - :nosignatures: - :template: myclass.rst + :toctree: generated + :nosignatures: + :template: myclass.rst - openmc.data.ace.Library - openmc.data.ace.Table + openmc.data.ace.Library + openmc.data.ace.Table Functions +++++++++ .. autosummary:: - :toctree: generated - :nosignatures: + :toctree: generated + :nosignatures: - openmc.data.ace.ascii_to_binary + openmc.data.ace.ascii_to_binary + openmc.data.write_compact_458_library .. _Jupyter: https://jupyter.org/ .. _NumPy: http://www.numpy.org/ diff --git a/openmc/data/fission_energy.py b/openmc/data/fission_energy.py index c22fef9a9..d7fe5fa72 100644 --- a/openmc/data/fission_energy.py +++ b/openmc/data/fission_energy.py @@ -1,7 +1,6 @@ from collections import Callable from copy import deepcopy import sys -#from warnings import warn import h5py import numpy as np @@ -199,6 +198,82 @@ def write_compact_458_library(endf_files, output_name=None, comment=None, class FissionEnergyRelease(object): + """Energy relased by fission reactions. + + Energy is carried away from fission reactions by many different particles. + The attributes of this class specify how much energy is released in the form + of fission fragments, neutrons, photons, etc. Each component is also (in + general) a function of the incident neutron energy. + + Following a fission reaction, most of the energy release is carried by the + daughter nuclei fragments. These fragments accelerate apart from the + Coulomb force on the time scale of ~10^-20 s [1]. Those fragments emit + prompt neutrons between ~10^-18 and ~10^-13 s after scission (although some + prompt neutrons may come directly from the scission point) [1]. Prompt + photons follow with a time scale of ~10^-14 to ~10^-7 s [1]. The fission + products then emit delayed neutrons with half lives between 0.1 and 100 s. + The remaining fission energy comes from beta decays of the fission products + which release beta particles, photons, and neutrinos (that escape the + reactor and do not produce usable heat). + + Use the class methods to instantiate this class from an HDF5 or ENDF + dataset. The :meth:`FissionEnergyRelease.from_hdf5` method builds this + class from the usual OpenMC HDF5 data files. + :meth:`FissionEnergyRelease.from_endf` uses ENDF-formatted data. + :meth:`FissionEnergyRelease.from_compact_hdf5` uses a different HDF5 format + that is meant to be compact and store the exact same data as the ENDF + format. Files with this format can be generated with the + :func:`openmc.data.write_compact_458_library` function. + + References + ---------- + [1] D. G. Madland, "Total prompt energy release in the neutron-induced + fission of ^235U, ^238U, and ^239Pu", Nuclear Physics A 772:113--137 (2006). + + + Attributes + ---------- + fragments : Callable + Function that accepts incident neutron energy value(s) and returns the + kinetic energy of the fission daughter nuclides (after prompt neutron + emission). + prompt_neutrons : Callable + Function of energy that returns the kinetic energy of prompt fission + neutrons. + delayed_neutrons : Callable + Function of energy that returns the kinetic energy of delayed neutrons + emitted from fission products. + prompt_photons : Callable + Function of energy that returns the kinetic energy of prompt fission + photons. + delayed_photons : Callable + Function of energy that returns the kinetic energy of delayed photons. + betas : Callable + Function of energy that returns the kinetic energy of delayed beta + particles. + neutrinos : Callable + Function of energy that returns the kinetic energy of neutrinos. + recoverable : Callable + Function of energy that returns the kinetic energy of all products that + can be absorbed in the reactor (all of the energy except for the + neutrinos). + total : Callable + Function of energy that returns the kinetic energy of all products. + q_prompt : Callable + Function of energy that returns the prompt fission Q-value (fragments + + prompt neutrons + prompt photons - incident neutron energy). + q_recoverable : Callable + Function of energy that returns the recoverable fission Q-value + (total release - neutrinos - incident neutron energy). This value is + sometimes referred to as the pseudo-Q-value. + q_total : Callable + Function of energy that returns the total fission Q-value (total release + - incident neutron energy). + form : str + Format used to compute the energy-dependence of the data. Either + 'Sher-Beck' or 'Madland'. + + """ def __init__(self): self._fragments = None self._prompt_neutrons = None @@ -453,8 +528,10 @@ class FissionEnergyRelease(object): obj.neutrinos = Polynomial(group['neutrinos'].value) if group.attrs['format'].decode() == 'Madland': + obj.form = 'Madland' obj.prompt_neutrons = Polynomial(group['prompt_neutrons'].value) elif group.attrs['format'].decode() == 'Sher-Beck': + obj.form = 'Sher-Beck' obj.prompt_neutrons = Tabulated1D.from_hdf5( group['prompt_neutrons']) else: @@ -471,7 +548,7 @@ class FissionEnergyRelease(object): fname : str Path to an HDF5 file containing fission energy release data. This file should have been generated form the - openmc.data.write_compact_458_library function. + :func:`openmc.data.write_compact_458_library` function. incident_neutron : openmc.data.IncidentNeutron Corresponding incident neutron dataset