The photon flux incident from all propagation directions, resolved by wavelength when needed for photodissociation. It is distinct from the net radiative flux through a horizontal surface; scattered and diffuse photons can contribute even when their net vertical flux cancels.

The fraction of transmitted light scattered sufficiently far from the forward direction under a specified measurement geometry. A transparent electrode can have high total transmittance yet blur an image if scattering is strong. State the collection angles and wavelength when comparing haze measurements.

Chemical transformation of water initiated by ionizing radiation. Both reducing and oxidizing products occur; observed net redox chemistry depends on the solution and reactions of primary products.

A waste form designed using durable mineral structures as hosts. A natural analogue motivates a design but does not substitute for tests of the actual radioactive composition.

Immobilisation of radioactive waste in a glass matrix. glass composition, durability, secondary phases and the complete package affect performance.

A waste form together with its container and any associated internal barriers prepared for handling, storage or disposal.

Removal of water vapour to concentrate mainly nonvolatile contaminants. Entrainment and volatile radionuclides can contaminate the condensate; a smaller concentrate volume does not guarantee a clean distillate.

Transfer of dissolved contaminants to separable solids by precipitation, coprecipitation or surface uptake. The resulting sludge requires separation and conditioning; residual dissolved radioactive activity must be measured.

radioactive activity per volume, in $\mathrm{Bq}{\mathrm{m}}^{-3}$. This differs from mass-specific radioactive activity, usually expressed per kilogram.

If scattering is elastic and there is no absorption or thermal emission in the band, the integrated outgoing energy equals incoming energy. Consequently net radiative-flux convergence and matter heating vanish even when the direct beam is almost extinguished.

Consider unit energy of incident radiation travelling downward into a conservatively scattering slab. Let $t$ be its unscattered transmission fraction. Of the fraction $1-t$ that scatters, suppose a fraction $a$ continues exactly forward and the remaining fraction $1-a$ has an isotropic outgoing distribution. Approximate every scattered contribution as escaping without a second interaction.

The isotropic part splits equally between upward and downward directions. The escape fractions are thereforeThey sum to one, as required by conservation of energy without electromagnetic absorption. For example, $t=0.6$ and $a=0.5$ give $f_{\uparrow }=0.1$ and $f_{\downarrow }=0.9$. Exactly forward scattering does not remove downward energy in this model; treating all scattering as backward loss would give a different result.

For a specified direct path, exponential attenuation gives $t=e^{-{\tau }_s}$ with scattering optical depth ${\tau }_s$. The single-escape assumption becomes unreliable when repeated scattering is important. A thick slab generally requires the angular scattering phase function and the full radiative transfer equation, rather than this two-branch bookkeeping.

In an optically thin plasma, radiative recombination removes the kinetic energy of captured electrons. A radiative recombination photon can also carry the binding energy released when a free electron becomes bound; that part is stored ionization energy, rather than newly removed thermal energy. The kinetic contribution per event is the recombination-weighted electron energy, which need not be $3k_{B}T/2$.

Equality with mean photoelectron heating requires two balances. If photoionization is the only ionization and heating process, and radiative recombination the only recombination and cooling process, photoionization equilibrium equates their event rates. Separately imposing thermal equilibrium then equates the mean heating energy per ionization to the mean kinetic cooling energy per recombination. Photoionization equilibrium alone does not do this: at the same balanced event rate, unequal energies can still heat or cool the gas. Additional atomic line cooling, collisional ionization or trapping of emitted photons changes the energy accounting.

A random-overlap model in which each independent radioactive decay damages a fixed volume. At constant event rate density $R$ and damaged volume $v$, the surviving crystalline fraction is $e^{-Rvt}$ and the amorphous fraction is $1-e^{-Rvt}$.

The fraction of a material lacking the specified long-range crystalline order. It is a structural measure, not directly a dissolved mass fraction or radionuclide release fraction.

Mean energy imparted by ionizing radiation per unit mass; its unit is the gray.

A radiation weighting factor weighted sum of mean absorbed doses for a specified organ or tissue. Its unit is the sievert.

A tissue weighting factor weighted sum of equivalent doses. Its unit is the sievert.

For three-dimensional radial wavefunctions with measure $r^{2}dr$, this formal symmetric momentum expression obeys $[f(r),p_r]=i\hslash f^{\prime }(r)$ on appropriate test functions and has square $-{\hslash }^2({\partial }_r^2+2{\partial }_r/r)$. It is useful in separating kinetic energy as $p^2=p_r^2+L^2/r^2$. Formal symmetry and these identities do not establish a self-adjoint momentum observable on the half-line; domains and origin conditions must be specified when taking adjoints or defining products.

A one-dimensional reference model combining elastic wave speeds, density and attenuation, developed by Adam M. Dziewonski and Don L. Anderson. It incorporates joint seismic and global integral constraints rather than treating density as a direct travel-time measurement.