# openmc.data.FissionEnergyRelease¶

class openmc.data.FissionEnergyRelease(fragments, prompt_neutrons, delayed_neutrons, prompt_photons, delayed_photons, betas, neutrinos)[source]

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 FissionEnergyRelease.from_hdf5() method builds this class from the usual OpenMC HDF5 data files. FissionEnergyRelease.from_endf() uses ENDF-formatted data.

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). <http://dx.doi.org/10.1016/j.nuclphysa.2006.03.013>

Variables
• 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).

classmethod from_endf(ev, incident_neutron)[source]

Generate fission energy release data from an ENDF file.

Parameters
Returns

Fission energy release data

Return type

openmc.data.FissionEnergyRelease

classmethod from_hdf5(group)[source]

Generate fission energy release data from an HDF5 group.

Parameters

group (h5py.Group) – HDF5 group to read from

Returns

Fission energy release data

Return type

openmc.data.FissionEnergyRelease

to_hdf5(group)[source]

Write energy release data to an HDF5 group

Parameters

group (h5py.Group) – HDF5 group to write to