Radiation transport and attenuation

A first article "Activation", presents the physical phenomena involved in activating materials and attenuating radiation to ensure the protection of people and equipment in nuclear facilities.

This article follows on from it, dealing with the calculation methods used to design radiation protection.

The aim is to determine, at a given point P (where personnel are located, for example), the particle flux φ (E) emanating from a source $S\left(\overrightarrow{r},E,\overrightarrow{\Omega },t\right)$ at an instant t.

Very high radiation attenuation is generally sought between the source and the area accessible to people: in the core of a fission reactor, neutron and photon fluxes of the order of 10 ¹⁴ n · cm ^–2 · s ^–1 , with energies of up to a few MeV, prevail, whereas in areas accessible to the public, we aim not to exceed dose equivalent rates of the order of µSv · h ^–1 corresponding to fluxes of the order of a few neutrons or a few photons cm ^–2 . s ^–1 . This involves taking into account a considerable number of radiation-matter interactions and solving the integro-differential transport equation linking φ (E) to $S\left(\overrightarrow{r},E,\overrightarrow{\Omega },t\right)$ 1 .

Attenuations as strong as the ones we've just mentioned require computational methods that provide an accurate representation of radiation-matter...