|
Nuclear heating results from the slowing down of energetic charged
particles produced in nuclear reactions, including the recoil
nucleus from scattering reactions. It is a very important quantity.
Sometimes it is the product being sold (as in power reactors), and
sometimes it is a damaging corollary of the nuclear reactions (as
in melting of important structural elements). The HEATR module of
NJOY can be used to compute estimates of energy-deposition cross
sections for neutrons that can be combined with calculations of
neutron fluxes in nuclear systems to compute the neutronic
contributions to nuclear heating. The heating due to the photon
flux in a nuclear system is usually even more important; it is
computed in the GAMINR module.
The same energetic charged particles and recoil nuclei that lead
to heating can also cause damage to the crystalline structure of the
materials that they pass through. An important case of this is
the embrittlement of power reactor containment vessels that is one
of the main limiting factors in the useful life of a commercial
reactor. HEATR computes the damage-production energy, which can be
correlated to macroscopic damage, such as tensile strength, ductility,
or resistivity, through phenomenological factors like DPA
(displacements per atom).
|