The Number of Transfer Units method is used to calculate the rate of heat transfer in heat exchangers (especially counter current exchangers) when there is insufficient information to calculate the Log-Mean Temperature Difference.

An N-type semiconductor is a type of material used in solar cells.

A nuclear and radiation accident is defined by the International Atomic Energy Agency (IAEA) as "an event that has led to significant consequences to people, the environment or the facility.

Nuclear binding energy is the minimum energy that would be required to disassemble the nucleus of an atom into its component parts.

A nuclear chain reaction occurs when one single nuclear reaction causes an average of one or more subsequent nuclear reactions, thus leading to the possibility of a self-propagating series of these reactions.

The nuclear cross section of a nucleus is used to describe the probability that a nuclear reaction will occur.

Nuclear decommissioning is the administrative and technical process whereby a nuclear facility such as a nuclear power plant, a research reactor, an isotope production plant, a particle accelerator, or uranium mine is dismantled to the point that it no longer requires measures for radiation protection.

Nuclear engineering is the branch of engineering concerned with the application of breaking down atomic nuclei (fission) or of combining atomic nuclei (fusion), or with the application of other sub-atomic processes based on the principles of nuclear physics.

Nuclear entombment is a method of nuclear decommissioning in which radioactive contaminants are encased in a structurally long-lived material, such as concrete.

Nuclear fission is a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into two or more smaller, lighter nuclei.

The fuel for nuclear fission reactor usually consists of a low-enriched oxide material (e.g.

Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission.

A nuclear flask is a shipping container that is used to transport active nuclear materials between nuclear power station and spent fuel reprocessing facilities.

The nuclear force is a force that acts between the protons and neutrons of atoms.

Nuclear fuel is a material that can be 'burned' by nuclear fission or fusion to derive nuclear energy.

The progression of nuclear fuel through a series of differing stages.

Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles (neutrons or protons).

A nuclear meltdown is a severe nuclear reactor accident that results in core damage from overheating.

Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions.

Nuclear potential energy is the potential energy of the particles inside an atomic nucleus.