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The A to Z of nuclear power for on-site machinists


Getting involved in portable machining projects within the nuclear power sector isn’t normally a quick and simple process. The unique nature of some projects (especially in nuclear decommissioning), the safety risks involved, getting security clearance, and the lengthy tender processes can be off putting to say the least.

But for those who do win the contracts, there’s plenty of familiar opportunities from on-site machining.

Away from the nuclear reactor, the fundamentals are pretty much the same as for fossil fuel power stations. There’s steam turbines to be maintained and plenty of pipe and flange joints to be kept safe and secure. 

So for those of you unfamiliar with the nuclear power sector and thirst for knowledge, we’ve put together an A to Z of the essentials. This is to give you a very basic introduction, so if you want to know more see the websites listed at the end of the article.

A - Alpha particle radiation 

Of the three radiation types (Alpha, Beta and Gamma), Alpha is the radiation with the lowest potential for penetrating materials. It can be stopped by a sheet of paper and is only dangerous for living creatures if the substance emitting alpha rays is inhaled or ingested with food or enters wounds.

B - Beta particle radiation

Beta particles are lighter than alpha particles, and they generally have a greater ability to penetrate other materials. They can travel a few feet in the air, can penetrate skin but a thin sheet of metal or plastic or a block of wood can stop them.

C - Controlled area

Areas in which persons may receive a ‘dose’ of radiation.

D - Dose

A dose is a measure of a radiation exposure using the international system of units (SI system) "gray" (Gy) and "sievert" (Sv).

E - Electron

A very small negatively charged particle which orbits the nucleus of an atom. It is a stable subatomic particle found in all atoms and acts as the primary carrier of electricity in solids.

F - Fission

This is the process occurring inside a power plant’s nuclear reactor. It is the release of energy where heavy element atoms are split up into smaller atoms, producing free neutrons and large amounts of energy.

G - Gamma radiation

One of the three radiation types, gamma rays are highly-energetic, short-wave electromagnetic radiation emitted from the nucleus of an atom. They are extremely penetrative and may best be weakened or stopped by material of high density such as lead.
The time taken for the radioactivity of a specified isotope to fall to half its original value.

I - Isotope

Isotopes of a given element have the same atomic number (same number of protons in their nuclei) but different atomic weights (different number of neutrons in their nuclei). Uranium-238 and uranium-235 are isotopes of uranium.

J - Joule

The SI unit of energy. The release of one Joule per second is one Watt.

K - Kilowatt

A measure of one thousand watts of electrical power

L - Lethal dose

This is an ionizing radiation dose leading to the death of the irradiated individual due to acute radiation injuries. LD1 is the dose leading to a mortality of 1% of the irradiated persons, LD99 is lethal for all (99%) persons irradiated.

M - Megawatt (MW)

A unit of power, one million watts
A large power plant such as the Palo Verde in Arizona) generates 3,872 megawatts from its 3 reactors.

N - Neutron

An uncharged elementary particle found in the nucleus of every atom - except hydrogen.

O - Oxide fuels

Enriched or natural uranium in the form of the oxide UO2, used in many types of reactor

P - Pressurised water reactor (PWR)

These constitute the large majority of the world's nuclear power plants (notable exceptions being the United Kingdom, Japan, and Canada) and are one of three types of light water reactor (LWR), the other types being boiling water reactors (BWRs) and supercritical water reactors (SCWRs).

R - Reactor

The reactor is the heart of a nuclear power plant. It is where nuclear fission is sustained and controlled in a self-supporting nuclear reaction.

U - Uranium

The fuel used in a nuclear reactor. It is the heaviest known naturally-occurring element, consisting of two isotopes: uranium-235, which undergoes fission, and uranium-238 which does not.

V - Vitrification

A process used to solidify concentrated solutions of fission radioactive waste by mixing them with a glass matrix at high temperature. Glass discs/ blocks are placed into long term storage where they are air-cooled while the radioactivity decays.

W - Waste

High-level waste (HLW) is highly radioactive material arising from nuclear fission. It requires very careful handling, storage and disposal.

Intermediate-level waste (ILW) comprises a range of materials from reprocessing and decommissioning. It is sufficiently radioactive to require shielding and is disposed of in engineered facilities underground. 

Low-level waste (LLW) is mildly radioactive material usually disposed of by incineration and burial

X - X-ray

X-rays are electromagnetic waves and ionizing, virtually identical to gamma rays, but not necessarily nuclear in origin.

Y - Yellowcake

Ammonium diuranate, the penultimate uranium compound in U3O8 production, but the form in which mine product was sold until about 1970. See also Uranium oxide concentrate

Z - Zircaloy

An alloy of zirconium, tin, and other metals, used chiefly as cladding for nuclear-reactor fuel.

Sources and more information: 

Read or CNC Gantry milling case study to find our what we did for the nuclear sector.





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