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Glossary |
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There are at all times two sciences in progress. Running side by side, the one is real, while the other is only apparent. The former is pursued by those who live for science. Its course is clearly guided by sober, responsible people who have conscience. Their concepts are clear and their aims noble. This group is the steam-engine of science. Like train engineers they are always at work and their work is to safely guide and illuminate the way. The latter kind of science is pursued by persons who live on science. They are all deadweight passengers on this train. For them, career growth is their only aim. Each pursues his own interests first. This is often propelled by the interests of governments and "big money" financial groups who thrust them forward to write "happy face" reports such as the September, 2005 UN report on Chernobyl. Now, let me explain why the nuclear industry fogs its information with jargon and doublespeak. Most nuclear industry reports are written by riders on science, and not writers of science. Often they have no clear idea of what they talking about. Their aim is to keep the public from the truth, so their way of expressing themselves is always obscure. They try to make the people believe that their research goes much wider and deeper than is really the case. They blather on in long, obtuse sentences that twist about in tortured and unnatural ways. They coin new words and write prolix paragraphs which wind round and round the facts, as if to wrap them up tightly in a sticky cocoon of mush and mucous. Reading and comprehending their reports is like peeling onions and cabbage. To get past the dry and often decaying layers, one must discard much before getting into the facts. Often there is corruption clear to the core. The authors seem to twitch between the two incompatible goals of communicating what they want to say and of concealing it for the sake of their masters. Their object is to festoon their work so that it looks learned or deep, hoping to give people the impression that there is very much more in it than there really is. At the other extreme, some jot down their thoughts bit by bit in short, but ambiguous and paradoxical, sentences. This method, seemingly profound and scientific, sedates the reader with the numbing effect of assault-style sentences, lacking even a single idea among them. This proves they write down words, even whole sentences, without attaching any real meaning to them, in the hope that it is so hard to break through the nutshell of their pseudo-scientific language that no reader will discover that there is no kernel inside - or at best the kernel is shriveled or rotten. It's quite understandable, that after more then fifty years of obscurantism in the field nuclear science, it is now bedeviled with jargon and acronyms, all apparently intended to be confused with scientific fact. Their vocabulary changes all the time. The glossary on this page mainly contains terms and expressions which were in use in 1986, at the time of the Chernobyl nuclear accident and before. I briefly mentioned becquerel, sievert and gray that were introduced right after Chernobyl. Those indicate the rate at which disintegrations are taking place and its biological significance. This type of measurement takes into account the way in which the radionuclides behave in the body, their biological half-life and their physical half-life and whether or not they tend to concentrate in particular organs. More information about those and other new measures can be found on the internet, my purpose is to preserve vocabulary of the time of Chernobyl accident.
AGR (Advanced Gas-Cooled Reactor)
AGR belong to group of Gas-cooled reactors and has much higher efficiency, since the coolant reaches a temperature of 650C, more than 300C higher than normal Magnox operating temerature.
Alpha particle
Nucleus of the helium atom, consisting of two protons and two neutrons. Alpha particles are emitted from the nuclei of some radioactive substances in the process of decaying into other elements.
Americium-241
Daughter of Pu-241, the physical half-life 458 years with an effective (in the body) half-life of about 100 years. Am-241 is alpha emitter and requires special and delicate detectors.
Atom
Smallest amount of an element
which can exist independently and still retain the chemical properties
of that element. It consists of a nucleus around which small particles,
electrons, travel in orbit.
When we talk about "splitting
the atom" it is not strictly correct, for it is nucleus of the atom
which is split. Let's imagine taking a small piece of any mineral and
continuing to cut it in half, we will finally reach a stage where, if we
were to divide it any further, what we would be left with would no
longer be that mineral. At this stage, while it still remains intact,
what we have is an atom.
But if we keep on cutting
away at it the next part we will remove is called the electron, and it
is negatively charged. The remainder of the atom is positively charged.
The part we have removed has become a negative ion and what are left are
positive ions. Every time we remove another ion those that remain become
more strongly positively charged. But if we finally succeed in cutting
them all away, what we are left with is the nucleus of the atom itself.
This contain only positive charges, immensely strengthened and held
together by a tremendous power. It is the shattering of this nucleus and
the release of the awesome power within it which produces a nuclear
bomb. Carefully controlled, in what is known as a controlled chain
reaction, it can produce nuclear power.
Auxiliary absorbers
When a reactor has just been loaded with fresh fuel, its ability to increase neutron power exceeds the ability of the absorbent rods to suppress the chain reaction. In such circumstances, parts of the fuel bundles are withdrawn, and stationary absorber rods known as auxiliary absorbers are inserted in their place to assist the movable rods. As the uranium is gradually burned up, those auxiliary rods are removed and replaced by nuclear fuel.
AZ (Emergency power reduction system)
Red button which Alexander Akimov pressed at 1:23:40 and in 20 seconds reactor at Chernobyl
exploded. Many blame him for activating the emergency power reduction system, which gave reactor a prompt neutron power surge. Akimov struggled to the end, he has
received a lethal dose of radiation and died in 3 weeks agonizing death.
One unit of disintegration per second, or one count of radioactivity per second. It is also a very small measurement, so small that it is colloquially known in the trade as a "baggerall". It is unit now used for measuring radiation in milk and water. Becquerel was introduced after Chernobyl accident.
Beta particle
High-energy electron emitted by radionuclide.
Blanket
Fuel elements surrounding the core in a fast-breeder reactor; these contain uranium-238, which is converted to plutonium by neutron bombardment.
Breeder
Reactor that produces more fissile material than it uses.
BWR
Acronym for boiling-water reactor. BWR is one of variants of a general reactor type known as light water reactor (LWR) It uses ordinary water (light water) as both coolant and moderator.
Fission product; a hazardous beta-emitter. Caesium-137 is deposited in muscles of the body where it can produce malignant changes.
Cascade
The aim of enrichment is to increase the proportion of fissile uranium-235 atoms within uranium. For uranium to work in a nuclear reactor it must be enriched to contain 2-3% uranium-235. Weapons-grade uranium must contain 90% or more u-235.
A common enrichment method is a gas centrifuge, where uranium hexafluoride gas is spun in a cylindrical chamber at high speeds. This causes the slightly denser isotope u-238 to separate from the lighter u-235. (illustration attached)
The dense u-238 is drawn towards the bottom of the chamber and extracted; the lighter u-235 clusters near the centre and is collected. The enriched u-235 is then fed into another centrifuge. The process is repeated many times through a chain of centrifuges known as a cascade.
The remaining uranium - essentially u-238 with all the u-235 removed - is known as depleted uranium.
Chain reaction
Self-perpetuating process whereby the fission of one nucleus releases neutrons which cause the fission of other nuclei and so on.
Chernobylit
Radioactive magma, inside of
sarcophagus that looks like crystal and has a form of stalactite/stalagmite. Consist mostly of melted sand that has absorbed a large amount of fuel from the reactor.
Chernobyl type reactor.
Chernobyl reactor was of the generic RMBK (light-water
pressurized-tube graphite-moderated reactor) 1000-megawatt nuclear reactor was using graphite as a moderator and water as a coolant. Twenty years after the accident, there are still four RMBK reactors operating in Russia. (illustration attached)
"China syndrome"
Theoretical consequence of a core meltdown, when the heavy molten mass of highly radioactive material actually goes straight through the vessel in which it had been contained and down through the earth's core. With the other words, China syndrome
occur when out-of-control reactor burns its way downwards towards the earth's core. From the US, it would reappear in China.
Cladding
Metal sheath that seals in the reactor fuel.
Control rod
Rod of neutron-absorbing material inserted into a reactor core to soak up neutrons and shut off or reduce the rate of the nuclear reaction.
Conversion
Stage in the nuclear fuel cycle after mining and before enrichment.
Critical mass
A nuclear reaction will only take place if there are enough u-235 atoms present to allow this process to continue as a self-sustaining chain reaction. This requirement is known as "critical mass".
Coolant
Liquid, usually water or gas (carbon dioxide, helium, air) piped through a reactor core to remove heat generated in it.
Cooling pond
Deep tank of water into which spent fuel is discharged from a reactor. It then requires either
shipment for reprocessing or storage.
Critical
Or "going critical": the point in a chain reaction when neutrons are being captured and released at exactly the same rate.
Curie
Quantity of a radioactive isotope that disintegrates at the rate of 37,000 million disintegrations per second. Named after early pioneer in the field Marie Curie who with her daughter Iren both died of aplastic anaemia at the ages of 67 and 59 respectively.
Element caused by the transformation of one substance into another through decay.
Decay
Disintegration of radioactive elements over time, releasing radiation.
Depleted uranium
Uranium with less than the natural proportion (0.7%) of uranium-235; the latter is removed in the enrichment process and transferred to enriched uranium.
Depleted uranium, a heavy and slightly radioactive metal, is used as a component in
armor-piercing shells and other munitions.
Dirty bomb
Primitive explosive device, filled with spent fuel from atomic power plants or other radioactive waste materials or chemicals. It does not produce a self sustaining fission reaction and therefore dirty bomb do not posses the power of destruction. It spread chemicals over the land and creates the effect of Chernobyl.
Dose
Amount of energy delivered to a unit mass of material by radiation
traveling through it.
Dose rate
Time rate at which radiation delivers energy to a unit mass of a material through which it is passing.
Dosimeterist
Radiation protection specialist
Dosimeter
After Chernobyl accident people start calling
Geiger counters - dosimeters. Perhaps, the reason is because counters were devices of dosimeterists. It is not correct, for dosimeter is device used to measure an individual's exposure to radiation, it measures the cumulative dose of radiation received by the device.
Negatively charged particles that travel around the nucleus of an atom.
Elephant's Foot
Formation of radioactive fuel inside of Chernobyl sarcophagus. The mass is more then 2 meters across and many tons. Because of it's shape it was named the "Elephant's Foot". At least 50% of nuclear fuel inside of sarcophagus is thought to be trapped in this glassified form.
Enrichment
Process of increasing the concentration of the isotope uranium-235 beyond the 0.7% contained in natural uranium.
Uranium enriched to around 5% can be used as nuclear fuel, but if it is enriched to around 90% it can be used in a weapon.
Radioactive-fission products created by nuclear
explosions which fall back to earth as a dust.
Fast breeder
Reactor that is fuelled with a mixture of plutonium and uranium oxide and has no moderator to slow down the neutrons. Known as an FBR.
Fissile
Isotope of an element whose nucleus will split upon being hit by a neutron in a spontaneous process when a critical mass is formed. Uranium-235 and plutonium are fissile.
Fission
Division of the atomic
nucleus into two lighter fragments releasing energy. In a nuclear power station fission occurs slowly, while in a nuclear weapon, very rapidly. In both instances, fission must be very carefully controlled.
Fuel
Arrangement of fissile material in a reactor. It can be natural uranium in some, slightly enriched in other, while some military reactors use highly enriched fuel. Others use plutonium. Enriched fuel contains plutonium-235.
Fuel cycle
Stages in the production of nuclear power from mining the uranium to disposal of the waste.
Fuel pin/rod
Single tube of cladding filled with pellets of fuel.
Fusion
Merging of two light nuclei to make a heavier one, releasing energy.
Technical definition of gamma ray is high energy
electromagnetic radiation emitted by the nucleus, of great penetrating
power. The gamma radiation is made up of photons, as visible light or
X-ray, but it is much more energy. The visible light has an energy of
about one electron volt (1 eV), a unit used by physicists. X-rays have
an energy of a thousand to a million of eV, while the gamma rays can
reach an energy of a million million eV (one Tera-electronvolt or
1,000,000,000,000 eV). Due to this very high-energy gamma rays are very
penetrating.
Gas centrifuge
Gas diffusion
Another method of enrichment is known as diffusion. It is alternative to
centrifuge. This works on the principle that of the two isotopes present in uranium, hexafluoride gas, u-235 will diffuse more rapidly through a porous barrier than its heavier cousin, u-238. As with the centrifuge method, this process must be repeated many times.
Gas cooled reactors
Group name for Magnox, AGR and HTR reactors. Unlike
pressurized water reactors, gas-cooled reactors have a separate moderator and coolant. As in the PWR, the nuclear reaction is controlled by neutron absorbing rods.
Gray
Unit of exposure to radiation. A gray equals 100 rads and is the new measurement of absorption of radiation into the body. It was introduced after Chernobyl accident. A whole-body dose of 10 grays of high-energy radiation, delivered at one time is fatal to humans
Time taken for half the
atoms in a radioactive substance to disintegrate into atoms of another
element. The characteristic is constant for each particular substance.
Half life of each element is constant and unique. Some radio-nuclides,
for instance krypton-94 being born in reactor and live less then a
second, the others, like Potassium-40 were formed during the creation of
the earth. Due to its long half-life of 1.28 billion years Potassium-40
is still present on earth.
HTR
Acronym for high-temperature reactor, which belongs to family of Gas-cooled reactors and works on highly enriched uranium (up to 93% in
comparison with an AGR enrichment level of around 2%)
Biologically hazardous fission product with a half-life of eight days. Radioactive iodine is
absorbed through the bowel wall and migrates through
the blood into the thyroid gland, where it may
produce both cancerous and non-cancerous growths.
The human thyroid gland is responsible for an
unusual nuclear health hazard. In the first days
after the accident, the absorbed radiation being
re-emitted by the thyroid of many people who
were close to reactor was as much as 50 roentgens
per hour. Under such circumstances the thyroid
irradiates the body even beyond the dose received
from external sources. People were being poisoned
with extra roentgens from their own thyroid glands.
State of reactor right after the accident. On 27 April an analysis showed that 50 percent of the radioactive particles consisted of Iodine-131.
Ion
Atom or molecule that has lost or gained one or more electrons and is thus positively or negatively charged.
Ionizing radiation
Any form of radiation that knocks electrons from atoms, turning them into ions.
Irradiation time
Length of time that fuel spends in a reactor being bombarded by neutrons.
Isotopes
Atoms of the same chemical element but with a different atomic mass, i.e. having the same number of protons in the nucleus but different numbers of neutrons.
1000 watts.
Krypton 85
Chemically inert gas that is a fission product released into the atmosphere by reprocessing plants.
Kurchatova institute
The institute of atomic energy in Moskov.
Cancer-like disease of the blood
characterized by a proliferation of white cells. It can be caused by exposure to radiation, but it is not exclusively due to such exposure.
Light water
Ordinary water used as a coolant and/or moderator.
Light-water reactor
A group name for either a Pressured-Water Reactor or a Boiling-Water Reactor. Known as an LWR.
LOCA
Acronym for loss of coolant accident.
Low level
Radioactive waste with a short half-life.
In the Magnox reactor, whose name derives from the material used for fuel cladding, natural uranium fuel is used. Heat generated in the core is transferred to the carbon dioxide coolant which is circulated past boilers (steam generators) Heat transferred to the boilers by the coolant gas causes the water inside them to boil, and the steam created is fed to turbines driving the electrical generator. Magnox belong to family of Gas-cooled
reactors (illustration attached).
Manhattan Project
Codename for the World War II project that developed the first atomic bomb.
Maximum permissible level
Radiation dose defined as the upper limit to which people can be exposed. The maximum permissible dose for nuclear power plant operators is 5 rems or 5 roentgens per year. For the rest of population it is tenth of that- 0,5 roentgen per year or 500 milliroentgens. Divide that by 365 days and you find that an ordinary mortal is entitled to absorb 1.3
milliroentgens (1300 microroentgens) per 24 hours, which is 54
microroentgens per hour. Those are the standards set by the World Health Organization. The highest I measured where people lived in 2006 was 250 microR per hour, this is 4.6 times higher than the WHO norm.
(In Chernobyl all this mathematics is pretty useless, because there is no way to count particles we inhale and chemicals we receive with food)
Megawatt
1 million watts.
Meltdown
When the reactor core overheats, thus allowing part of all of the solid fuel in a reactor to reach the point and temperature at which the cladding (and possibly the fuel and the structure that supports it) would liquefy and collapse - the ultimate nuclear accident, which nearly happened at Three-Mile Island.
Mining uranium
Uranium is the basic raw material of both civilian and military nuclear programs. When uranium is mined from the ground it emits the radioactive gas called radon. When inhaled into the lungs of miners, after four days radon converts to lead-210 which remains radioactive for more than a hundred years. Because radiation in the body is carcinogenic, lung cancer is a
professional disease for uranium miners. In the Soviet Union convicts were forced to work in the uranium mines. Even today we have this saying- "You'll
go to the uranium mines for that", meaning one will be punished severely.
Moderator
Material used to slow down neutrons in a reactor to enable them to be captured and allow fission. Moderators include graphite, water and heavy water.
Sodium potassium alloy with a low melting point, used as a coolant in early fast-breeder reactors and as an emergency coolant in some others.
Neutron
Uncharged particle in the nucleus of the atom, which is released during fission.
Nucleus
Centre of the atom that contains all the protons (positively charged) and neutrons (uncharged). It comprised almost all of the mass of the atom.
Nuclide
Nucleus of an isotope.
Name used for the original nuclear reactors, where "piles" of uranium were cooled by gas or water and moderated by graphite or water.
Plutonium
Heavy, totally synthetic metal made by neutron bombardment of uranium. It has 94 protons and the atomic nuclei are fissionable. Extremely toxic and highly chemically reactive, half-life of Plutonium-239 is 24,400 years.
Plutonium is one of the most carcinogenic substances known. The route of entry of plutonium is by inhalation of contaminated air into the lungs. Small particles of Plutonium are deposited deep in the respiratory passages, where they tend to remain for years. It is accepted that one millionth of one gram of plutonium is sufficient to produce lung cancer fifteen to
twenty years after initial inhalation of the element.
Plutonium is also causes sarcoma and
leukemia. Because of it's incredible gene-changing properties, it may cause an increased incidence of deformed and diseased babies, both now and in future generations.
Plutonium is appropriately named after Pluto, god of the dead and ruler of the underworld. By extrapolation, 1 lb (less then half kilogram) of plutonium, universally disposed, would be enough to kill every living human being on the earth.
Plutonium bomb
As a trans-uranium element, Plutonium offers several advantages over uranium as a component in a nuclear weapon. They call it a potential weapon of terrorists, because only about 4kg of plutonium is needed to make a bomb. A crude plutonium bomb could be designed and assembled without possessing greater level of skill A warhead consists of a sphere of plutonium surrounded by a shell of material such as beryllium, which reflects neutrons back into the fission process. This means that less plutonium is needed to achieve critical mass and explode. A terrorist group or country may find it easier to acquire plutonium from civil nuclear reactors, rather than to go through process of enriching uranium. Only a relatively small facility would be needed to produce 10-12 kg of plutonium per year, the components could also be obtained on the black market of nuclear materials, being alpha emitter Plutonium is not easily detected and can be smuggled, such a device could be easily transported in a car and would explode with the power of 100 tonnes of TNT - 20 times more powerful than the largest terrorist bomb attack to date. Also associated with terrorist device known as "suitcase bomb." Unlike to dirt bomb, a crude plutonium bomb produce a self sustaining fission reaction and posses the power of destruction.
Pressure vessel
Large container of welded steel or pre-stressed concrete which contains the reactor core, etc.
Pressurizer
Found in a Pressurized-Water Reactor (PWR): Electrically heated boiler in a cooling system, which boils water as necessary to maintain coolant pressure.
Proton
Positively charged particle that is a constituent of a nucleus.
Potassium iodide
Is a chemical that when, ingested, readily enters the thyroid gland. If taken in sufficient quantity before exposure to radioactive iodine, it can prevent the thyroid from absorbing it.
PWR
Acronym for pressurized-water reactor. PWR works on following principle: Heat created in the core is transferred to the
pressurized (primary) cooling water which circulates through U-shaped tubes in the stream generators. This causes
feed water at lower pressure, which is injected into the side of the steam generator, to boil. Steam taken from the top of the steam-generator drives turbines and is condensed to water and returned to the steam generator. The schematic drawings of PWR attached to "Glossary"
PWR is one of variants of LWR (light water reactor) because it uses ordinary water (light water) as both coolant and moderator. The basic design of all PWRs is the same, but the number of steam generators used depends on the size of the plant. Submarine reactors are equipped with just one steam generator, which is used to drive a steam turbine connected
directly to the propeller shaft.
Unit of the radiation that can be absorbed by tissue.
"Rad" stands for "Radiation absorbed dose". After Chernobyl it was superseded by gray. 100 rad equivalent to 1 gray. 1000 rad of high-energy radiation, delivered at one time, is fatal to humans. First victims- firefighters, atomic plant works who received doses of 1000 rad or more, all died within weeks.
Radiation protective means.
Includes a wide variety of gas masks,
respirators, lead tunics and specially impregnated uniforms. Typically these
can stop only 60% of radiation. Not much help if someone is going into
fields of high radiation. There is no means, no technology, that can protect
humans from the radiation. Nothing can stop gamma rays. The only real
defense for the individual is to know safe exposure-time allowable for level
of radiation being encountered. If those levels too high or can not be
detected by you device, then there is no other rule or prescription for
saving yourself, except for one that applies for the plague or ticking mine.
Run as far and as fast as you can.
Radioactivity
Behavior of a substance in which the nuclei are undergoing transformation and emitting radiation.
Radio-isotope
Radioactive isotope.
Radio-nuclide
Radioactive nuclide.
Radon
Alpha-emitting radioactive gas given off by radium.
Reactor
Arrangement to create and control a chain reaction.
Rem
Unit for measuring radiation doses, which takes into account the degree of harmful effects on biological tissue caused by each type of radiation - e.g. exposure to one roentgen of X-rays gives an absorbed dose of one rem. The term comes from "roentgen equivalent:man."
Reprocessing
Reprocessing is the chemical operation which separates useful fuel for recycling from nuclear waste.
Roentgen
Unit for measuring a radiation dose, measured by the number of ions released in a gram of air by X-rays or gamma rays. Unit named after W. K. Roentgen, discoverer of X-ray, who died from own invention, of bone cancer.
Runaway
Accidental, uncontrolled chain reaction.
Emergency shutdown of fission material in a reactor.
Shielding
Protective wall of material (concrete, lead, water) surrounding a source of radiation.
Sievert
New unit of measurement. Technical explanation - unit of radiation exposure, compensated to allow for extra biological damage. Simply, it means a unit which takes into account the effect of different kinds of radiation on human beings. It replaces the rem (Roentgen Equivalent: Man) although the term rem is still often used. 1 sievert equals 100 rem and sieverts are often described in millisieverts (i.e. thousandths of a sievert).
Spent fuel
Fuel that has undergone a chain reaction and is nearing the point where it can no longer do so because its fissile material has been transformed into other elements and has thus been removed from the reactor. Spent fuel can be used for producing dirty bombs.
Strontium-90
Hazardous beta-emitter with a half-life of 28 years. It is accepted by plants, animals, people, etc. as an "analog" of calcium - that is, it is so similar to calcium that it is absorbed in the same way. It attacks the bones and can cause bone cancer.
Fine sand left over after extraction of uranium ore. It contains radium and emits radon gas.
THORP
Acronym for thermal oxide reprocessing plant.
Heaviest natural element, a metal. Isotopes 233 and 235 are fissile, 238 fertile. It is an alpha-emitter.
UBS (Upper Biological Shield)
1000 ton cap on the nuclear containment vessel, a circle 15 m (49 feet) in diameter, consisting of two thousand cubes, each of them sits like a cap on top of a fuel channel containing a fuel bundle. In Chernobyl it was blown with explosion and fell on edge of the reactor vessel where it rest ever since. Chernobyl reactor had only one shield, many blame RMBK reactors for the
absence of secondary containment. Before explosion UBS of Chernobyl reactor was known as "Pyatachok" (five copek piece) After the accident it got a new name- "Elena"
Fusing of high-level waste into glass-like blocks.
Once extracted, uranium ore is taken to a mill to be crushed and ground into a fine powder. This is then purified in a chemical process and reconstituted in a solid form known as "yellow cake," due to its yellow
coloring. Yellow cake consists of 60-70% uranium and is radioactive.
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