Jargon buster

Jargon and Abbreviation Buster
Radiation Protection is stiff with jargon, acronyms and abbreviations.

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ABCC Atom Bomb Casualty Commission; In late 1945 the US Army surgeons said that all deaths due to the radiation effects of the Hiroshima and Nagasaki bombs had already happened. However in 1950 or thereabouts the Americans set up the ABCC to examine causes of death in 109,000 survivors, chosen from 284,000 identified in the 1950 census of Japan, and compared with a supposedly non-exposed control group. ABCC is now replaced by the Radiation Effects Research Foundation.
Absorbed dose a quantity of ionising radiation expressed as the amount of energy imparted to a unit mass of matter such as body tissue. It used to be measured in rads and is now measured in grays (Americans still use rads).
The fact that, by definition, absorbed dose is an average lies at the root of many arguments over the health effects of low levels of radioactive pollution. There are many forms of exposure (e.g. hot particles) which deliver all their energy into microscopic volumes of tissue; it is completely invalid to conceive of these high densities of energy deposition as an average. It is as stupid as saying that a gunman in a packed football stadium can't hurt anyone because the crowd would share the energy from his bullets and no-one would get a dose bigger than a friendly pat on the back.
The CERRIE majority report stated that “... the actual concepts of absorbed dose become questionable, and sometimes meaningless, when considering interactions at the cellular and molecular levels.” When challenged over this, Bob Smith of the UK Environment Agency replied "That is not to say that those concepts are lacking in utility within a radiation protection system ... It continues to be best scientific practice to use these dose coefficients in assessing effective doses to members of the public …. ". Effective dose is derived from absorbed dose, so what he's saying is that it's ok to use one absorbed dose quantity to assess another absorbed dose quantity.
Actinides The fifteen elements with atomic numbers 89 to 103. This includes Uranium and Plutonium
Alpha particle A particle consisting of two protons and two neutrons which has a double positive charge and a mass four times that of a proton. This is not the same as an alpha emitting particle - which is a lump of one of the elements (e.g. Plutonium and Uranium) which release alpha particles when atoms of that element undergo radioactive decay. A half micron particle of Uranium would be about 5000 times the diameter of an alpha particle. The alpha particle is destroyed by interactions with matter (such as your DNA), but the alpha emitting Uranium particle is virtually indestructible.
Americium or Am. An entirely man-made radioactive element created by the neutron bombardment of Plutonium. Am241, used in some types of domestic smoke detector, is relatively long-lived (half life is 458 years) and a very active alpha emitter (1167 million Bq per milligramme)
Article 31 Group of Experts People appointed by the Science and Technology Committee of the European Commission under Article 31 of the Euratom Treaty (q.v.) to advise the European Union on radiation protection issues. Notable for sparse information on membership and for publishing without review and without authors being identified. It is this group which decides that the European Union must rely on the advice of ICRP (q.v.).
Atomicity According to Hutchinsons atomicity refers to the number of atoms of an element that combine together to form a molecule.
Another online dictionary gives atomicity - n. - 1 the number of atoms in the molecules of an element and 2 the state or fact of being composed of atoms.
Jack Cohen Joppa of NukeResister, addressing comparisons which other workers make between Depleted Uranium and the Nagasaki bomb (e.g. DU in Iraq is equivalent to 250,000 Nagasaki bombs) says the unit measured is an intellectual construct coined by a Japanese scientist. "Atomicity" is simply the calculated number of radioactive atoms involved, with no regard for the type of radiation present, its relative biological impact [and] method of dispersal. He says: Such comparison is meaningless at least, misleading at worst.
LLRC points out that it's no more meaningless than the concept of Dose (q.v.), which conventional risk agencies use to predict that there would be no health effects from DU.
Bayesian Smoothing A statistical technique used to correct for random fluctuation of events in small populations by putting them into the context of what would be expected in a larger population where variation would be less.
Where people want to play down the significance of an elevated risk they adopt the assumption that it's a random fluctuation and use Bayesian Smoothing to massage the rate down towards the average. Using this kind of logic you could reason that you don't find any squashed hedgehogs in the fields, so hedgehogs are not at risk of being squashed when they run across the road.

Technically, Bayesian methods involve a specification of the subjective prior knowledge of the relative risks that must be estimated. Essentially the method involves correcting the area Standardised Mortality Ratio (SMR) towards the mean, with the size of the correction depending on the size of the population in the given area. Thus an area where there is a larger population will be corrected to a lesser degree than one with a smaller population. If the population is small the posterior estimate will be close to the overall mean. In one of the most widely used empirical Bayes methods the gamma distribution is used as the prior for the relative risks (the gamma distribution being the Bayesian conjugate of the poisson in frequential statistics).
The maths is
estimated relative risk= [observed cases+(mean^2/variance of the gamma distribution)]/
[expected cases+(mean/variance of the gamma distribution)]
so if "Observed" and "Expected" are small the corrected SMR will become more or less M, the "mean", but if o and e are large the smr will be close to the SMR as calculated in the normal way. (Roughly paraphrased from Elliott P, Martuzzi M ,Shaddick G. Spatial statistical methods in environmental epidemiology: a critique. Statistical Methods in Medical Research 1995:4:137-159.)

When looking at cancer risks around nuclear plant the problem is that the numbers involved are generally small. This is especially the case where we are looking at specific exposures such as the inland migration of particles originating from the sea; the exposure area is very small because the radioactive particles tend to be deposited close to the sea. Applying Bayesian Smoothing to such data denies us the opportunity to learn from real world information.

Becquerel (Bq.) A measure of the amount of radiation given off by a radioactive substance. A Becquerel is "one disintegration per second". It can express a concentration of radioactivity, e.g. 200 Bq. per gramme, or a total quantity, e.g. emissions limits for nuclear plant are given as so many Becquerels per year.
Bq replaces the earlier measure "Curies" [q.v.]
BEIR Biological Effects of Ionising Radiation. American committee periodically dragged out of its coffin by the NAS (after dark of course) to carry on ignoring low dose effects.
Beta particle A particle with a mass and charge equal to those of an electron.
Bi-phasic dose-response curve A Dose-response curve is a picture (or graph) of the relationship between how much an effect changes as you change the amount of the cause of that effect.
In this case, it's the relationship between radioactive pollution and genetic mutation. The conventional idea is that they are in strict proportion to each other, giving a straight line on the graph - in other words, the relationship is linear. A Bi-phasic curve, which has been derived from studies of disease in exposed populations, shows two peaks with a dip in between. This means that low doses have a greater effect per unit dose, followed by a reduction at slightly higher dose, followed by an increase at yet larger doses. For more on dose-response curves see explanation on another page
Bq. see Becquerel
Background Radiation see NBR
BRC Beneath Regulatory Concern, a term denoting concentrations of radioactivity which the industry and its regulators think they can ignore.
BSS The Basic Safety Standards Directive of the European Union
CEDE (Collective Effective Dose) (or Collective Effective Dose Equivalent) see Collective Dose.
CERRIE Committee Examining Radiation Risks of Internal Emitters. An oppositional committee set up by the UK Environment Minister in 2001. Notable for caving into legalistic threats from Departmental lawyers right at the end of its two-and-a-half year deliberations, banning a Dissenting Statement from being published in its Final Report despite earlier undertakings.
Ci see Curie
Clearance Under the Basic Safety Standards Directive [see BSS] contaminated materials and wastes from nuclear licensed sites will be subject to thresholds expressed in terms of Becquerels per unit mass. If they are less radioactive than these thresholds they may be regarded as being not radioactive at all, and may be cleared -- i.e. dumped, sold, and used in any way, irrespective of where they will end up.
A synonym for BRC [q.v.]
Collective Dose (or Collective Effective Dose Equivalent) The logical next step from accepting that there is no threshold dose below which ionising radiations can not cause genetic mutations (see LNT), Collective Dose is the sum of the effective dose equivalent to all the people exposed. It's expressed in units of man-rems or man-sieverts. See Effective Dose.
Collective Dose is important because it is a means of assessing the impact of radioactive pollution on large populations over long periods of time -- there's no reason why you could not extend the calculations to the entire human race over the next several thousand years, and many people see very good reason to do so, given how long nuclear waste remains a problem. ICRP is (as of 1999 - 2001) bent on dumping the concept of Collective Dose, because it is too costly for their mates in the nuclear industry to take care of people who, while they may die from the radiation, will never be able to stick the rap on the nukes. See also "Controllable Dose".
COMARE Committee on Medical Aspects of Radiation in the Environment. Set up to advise Government in the aftermath of Yorkshire TV's discovery of the Seascale cluster of childhood leukaemia. Notable for failure to challenge NRPB's appallingly unscientific view of health detriment from radioactive pollution and for biased investigation of phenomena which don't fit with that view. COMARE is supposed to be independent, but the secretary also works inside the Department of Health and hangs out at NRPB.
Controllable Dose ICRP's idea for allowing the nukes to pollute anybody and everybody with radioactivity up to an arbitrary threshold which they want to set somewhere around the point at which a person who got cancer might be able to persuade a court of law that the nukes had caused it. ICRP puts it thus:... so long as the individual most exposed to radioactivity from a particular source were adequately protected, then everybody else would be adequately protected. They will no longer take into account the incidence of disease from radiation-induced genetic mutation at low doses, though it is inevitable according to the No Threshold model espoused by ICRP.
What constitutes adequate protection is of course a political decision but ICRP (unelected and unaccountable) are making it for us.
Cosmic rays Penetrating high energy radiations (mostly gamma rays) emanating from outer space.
CPS counts per second - the rate at which a monitoring instrument registers radioactive disintegrations
Curies (Ci.) A measure of the amount of radiation given off by a radioactive substance, based on the radioactivity of one gramme of radium, which is one Curie (1 Ci.). Now replaced by the Becquerel (Bq). One Curie = 37,000 million Bq.
Decay chain When a radioactive atom decays (= spontaneously changes its energy state) it turns into a different isotope of the same element or into an atom of some other element. Decay chain is the series of incarnations it passes through before becoming stable.
Deterministic effects Deterministic effects are those which are certain to occur — acute and fairly immediate symptoms which a person will certainly suffer as a result of a large dose of radiation. They are effects such as hair loss, vomiting, diarrhoea and organ failure, usually termed radiation sickness. For external irradiation skin symptoms (reddening and burns) would occur at lower doses; these too are deterministic. Massive contamination with internal radioactivity will cause the hair loss, vomiting, diarrhoea and organ failure without the skin symptoms.
Stochastic effects. Since the way radiation affects body tissue means there can be no dose too small to cause some damage it follows that the lowest dose may cause a diagnosable health effect eventually. The conventional radiation risk model acknowledges this — it's the origin of the statement that there's no safe dose. Low dose effects are called stochastic effects (meaning determined by chance) and they appear later than deterministic effects. There is no certainty that they'll occur in any individual but they will occur in the exposed population (or its descendants) with a likelihood proportional to dose.
This analysis is not affected by the dispute over whether ICRP is right about what dose means for low levels of contamination; that dispute just affects the numbers of ill and dead people. However many or few people will sicken or die it will still be impossible to predict just who they'll be, and it's this randomness that makes the effects stochastic.
and see Stochastic effects below
DETR Department of Environment, Transport and the Regions:- a vast department of the UK government set up under John Prescott by Tory Blair's "new" Labour administration in 1997. Dismantled immediately after the 2001 General Election and revamped as Department of Environment, Food and Rural Affairs under Margaret Beckett -- to be known as DerFoora, perhaps? (We said it first). Prescott was kicked into oblivion to clean bogs at the Cabinet Office and MAFF was scrapped too (not before time!). The Transport and the Regions bits of DETR were transferred to another new department under Stephen Byers.
Disintegration The decay of a single atom of a radioactive element into a different element or a different isotope of the same element. Some elements are naturally unstable or have been rendered unstable by being bombarded with charged sub-atomic particles either from natural sources (cosmic rays or stellar supernovae) or in man-made nuclear fission processes (nuclear bombs or nuclear reactors or particle accelerators). [Some people - nuclear apologists mostly - will rabbit on about natural reactors - someplace in Africa where the concentration of Uranium was so high that it caused a chain reaction about gazillion years before dinosaurs had been thought of. Don't take any notice, it wasn't a big deal - they're just trying to distract your attention from the really big deal; the fact that the nukes have polluted the entire planet with cancer-causing junk.] Unstable in this context means the same as radioactive -- the atom has a finite (i.e. measurable or predictable) probability of decaying spontaneously, giving off charged particles. As far as the health effects go, it's the charged particles that do the damage, through their interactions with sub-cellular structures - DNA and membranes and so on (nobody actually knows what the critical targets are). See also Half life.
Dose Equivalent An attempt to approach the biological effects of radiation to offset the problem which the conventional radiation risk agencies have made by concentrating on the physical qualities. Absorbed Dose (q.v.) is the amount of energy transferred into body tissue; Dose Equivalent is a factor by which Absorbed Dose is multiplied to allow for differences in biological effectiveness of different types of radiation. This gives rise to Relative Biological Effectiveness (RBE). The most obvious example is the RBE of alpha particles, which is set at 20 on account of the tendency for alphas to kill cells. X, beta, and gamma rays have an RBE of 1. Pretty meaningless if what you want is to understand mutation effects at low dose. It used to be expressed in REMs (Roentgen Equivalent Man), which have now been replaced with Sieverts (where 100 rem = 1 sievert).
Dose response A Dose-response curve is a picture (or graph) of the relationship between how much an effect changes as you change the amount of the cause of that effect. (see also Bi-phasic)
Dose Dose is conventionally understood as energy transfer from ionising radiation into substantial volumes of body tissue, expressed as Joules per kilogramme, revealing the pivotal role physicists have played in this area.
The concept is useless at low dose. Radiation damage is caused by discrete events - single particles passing through tissue. Cells are either hit or they are missed. If they are hit the energy transfer (dose) can be high, if not, then the dose is zero. Cells that are hit may be damaged; the damage may or may not be repairable. If it is not repairable then the cell dies and causes no further problems, but if the damage is repaired it may be misrepaired, passing defects on to daughter cells. There are newly discovered field effects (or epigenetic effects which mean that cells near a cell that is hit may get the same symptoms as if they themselves had been hit (the bystander effect), and they may acquire genomic instability which shows up many cell generations after the exposure. These amplify the error in the conventional view since there are even more effects at low dose.
The notion of "dose" is virtually meaningless; every single radiation track may cause a mutation which may turn out to be deleterious or fatal to the individual person or to his/her descendants. Until you get into the realm where the exposure is so great / acute that you can predict the results with fair certainty (so-called deterministic effects) every exposure is a lottery - harm may or may not happen, and those that do happen may not be detectable. These are known as stochastic effects (see stochastic effects). By analogy the nuclear industry is forcing lottery tickets on us; the more tickets you get the greater are your chances of winning the deadly prize, but essentially one ticket is enough. True, some people and some cell types are more susceptible and some stages of development (e.g. foetus) are more sensitive; for these subpopulations each ticket will be more likely to pay off.
For more on the nonsense of "dose", see this link
Electron A particle with a small mass (1/1836 that of a proton) that has a negative charge.
Epidemiology The study of disease as it occurs in populations, rather than in individuals.
EURATOM European Atomic Energy Community, set up by the Euratom Treaty of 25th March 1957 - one of the founding instruments of what is now called the European Union (soon to be the United States of Europe, no doubt).
Article 1 says It shall be the task of the Community to contribute to the raising of the standard of living in the Member States and to the development of relations with the other countries by creating the conditions necessary for the speedy establishment and growth of nuclear industries. Time to repeal it, then.
Gamma ray A quantity of energy without mass or charge that is propagated as a wave. High energy short wavelength electromagnetic radiation emitted from the nucleus of an excited atom.
Gray (Gy) Unit of absorbed dose (q.v.); replaced obsolete Rad (q.v.)
Half life The time taken for half of any given quantity of a radioactive substance to decay to its daughters, which may also be radioactive and (just to confuse things) will have different half-lives (all the radioelements have different half-lives). Look at it another way - half-life is a measure of how unstable an element is, and that means how radioactive it is ; long half-life means not very unstable, or not very radioactive. Elements with long half-lives are axiomatically less unstable (than those with short half-lives), so any given mass of that element is less radioactive. Uranium is just about the practical limit, with a half-life equal to the age of the planet, meaning that half of the Uranium Earth inherited from the primaeval dust cloud (or whatever) is still here.
A spectacular amount of bollocks is talked about half-lives. It's commonly thought that long half-life is the same as big problem but it isn't as simple as that; long half-life just means Whatever is radioactive now will be radioactive for ages. Working out the health hazard is much, much more a matter of empirical research into actual health effects of actual exposures. Uranium is, once more, a classic example; in its natural form it is everywhere, including inside your body, but it's soluble so it's not concentrated anywhere, though its chemical affinity for DNA is a bit of a problem because of the Secondary Photoelectron effect (qv). On the other hand, insoluble ceramic particles from Uranium weapons can deliver damaging doses to local tissue in a way which natural (i.e. non-ceramic, non-particulate) Uranium could not achieve. The Ministry of Defence is profoundly culpable for using the common confusion of terminology to its own advantage - they repeat that natural Uranium is not very radioactive and that the depleted Uranium used in weapons is even less radioactive (i.e. has a longer half-life). So we are supposed to believe that it is therefore less hazardous. In fact the ceramic particle exposure route makes the half-life pretty irrelevant - the specific activity of the particles and the consequent chronic high local doses are much more important, and that's saying nothing about the Secondary Photoelectron effect.
Health Physicists Professionals who have to ensure that radiation safety standards are observed. The term physicists is revealing. The health effects of radiation exposure is not a matter of physics. Wouldn't it be more appropriate to have Health biologists, or Radiation medics? (see SWITCHEROO DD URL AND LINK for discussion of the first Health Physicist, Herbert Parker.
Health Protection Agency (HPA) See National Radiological Protection Board. From 2013 HPA became part of Public Health England.
Hormesis The word "hormesis" is derived from the Greek word "hormaein" which means"to excite" - so in the radiation protection context the idea is that "a small dose of radiation excites a protective response in the cell". Paracelsus wrote "All substances are poisons, there is none which is not a poison. The right dose differentiates a poison from a remedy."
Apologists for nuclear power regularly use this to support their case, claiming that a little bit of radiation is good for you.
Among the radiation protection community the conventional view is that hormesis is irrelevant because there is no dose below which genetic mutation (potentially fatal) cannot be induced. ICRP's Chairman wrote ... the postulate that low-dose irradiation induces additional DNA repair capacity lack[s] adequate supporting data and also fails to take account of the complex[ity of radiation induced] DNA damage ... [Clarke 1999]
LLRC says: "A protective mechanism which happens in cells (assuming that it does happen) cannot be assumed to extend to the whole organism - there may be unacceptable costs. The available epidemiology at low dose from internal radiation indicates effects 2 or 3 orders of magnitude greater than predicted by ICRP.
All the above is highly dependent on what exactly you mean by dose.
H PARP Health Protection Agency- Radiation Protection Department, formerly known as National Radiological Protection Board (see NRPB entry below). Same people, same 'phone numbers, same address, same mind-set.
IAEA International Atomic Energy Agency. Part of United Nations. Based in Vienna. Article 1 of the constitution requires IAEA to promote nuclear power. Since 1957 IAEA has had a power of veto over all other UN organisations' research projects.
ICRP International Commission on Radiological Protection, a desk puppet set up in the 1950s to protect the American Atom bomb industry. Self-appointed and self-perpetuating. The ICRP was reinvented from the pre-war International X-ray and Radium Protection Committee. (More.) Their recommendations have the status of "advice" but they are so deeply entrenched in the culture of radiation protection that they inform standards everywhere. ICRP is a charity registered in the UK, a status which seems to go unchallenged despite their obvious pro-nuclear bias.
Ionisation An ion is an atom or group of atoms that has lost or gained one or more electrons. An atom which has lost electrons acquires a positive charge and is known as a cation; an atom which has gained electrons has a negative charge and is called an anion. The process is called ionisation. Ionising radiation is a radiation of sufficient energy to cause the ionisation of matter through which it passes.
Isotope One of two or more forms of an element all having the same chemical properties but with different numbers of neutrons, different relative atomic mass, and different nuclear properties.
Kerma Kinetic Energy Released in Material
LNT See Linear No-Threshold
LET See Linear Energy Transfer
Linear Energy Transfer The average amount of energy lost per unit of distance travelled. Gamma rays are low LET radiations, because they blast through you without losing much of their energy; where they do lose energy through collisions with matter in your body the ionisations are well spread out along the length of the radiation track - in other words, what's low is the energy density. Alpha particles are high LET, since they lose all their energy within a few microns and the density of ionisations is high.
Linear No-Threshold (LNT) The hypothesis that health detriment is proportional to dose and that there's no dose too small to cause the detriment.
Most radiation protection specialists agree that there is no amount of ionising radiation too small to cause harm. This arises from two observations —
  1. that radiation affects us when charged particles pass through body tissue. The smallest dose is a single particle which can ionise atoms in its path, thereby causing damage potentially leading to mutation and disease;
  2. Muller's 1927 X-ray experiments showed the number of genetic mutations in fruit flies was proportional to dose.
The no-threshold idea is disputed by proponents of hormesis (q.v.)

The Linear aspect is the hypothesis that damage is proportional to dose. This is approximately correct where the radiation is well-averaged; otherwise it is manifest nonsense (see dose)

NAS National Academy of Science (US)
Natural Background see NBR
National Radiological Protection Board (NRPB) a.k.a. Health Protection Agency Radiation Protection Department (from 2005) and (from 2013) Centre for Radiation, Chemical and Environmental Hazards (CRCE) of PHE (Public Health England) NRPB was set up by the UK Parliament's Radiological Protection Act 1970. In 2003 it became part of the Health Protection Agency (HPA). On 1st April 2013 HPA became part of Public Health England, an executive agency of the Department of Health. Its Chief Executive is accountable to the Secretary of State for Health.
Little seems to have changed. The radiation protection staff are still based in the old NRPB building at Harwell. Their role is to provide expertise and specialist advice in dealing with radiation, chemical and environmental hazards.
Staff at NRPB and its successors do not see themselves as regulators - more as advisors; and neither do they see themselves as the ultimate source of the advice they hand down - that comes from ICRP, they say. The validity of this claim is dubious, given the overlaps between NRPB and ICRP [as well as the Article 31 Group of Experts (q.v.)]. Supposedly independent, NRPB was from the beginning a bunch of poachers turned gamekeepers. There is a big problem of culture - a highly defensive bunker mentality springs into action to repel any challenge to their modelling of radiation risk. It is clear that people in key positions are either not competent, or are not intellectually independent of the industries they advise on. In view of this incompetence and bias, the practice of publishing without peer review or with only internal review is a further problem (which is common to other advisory bodies - ICRP and the Article 31 Group).
NBR Natural Background Radiation. Naturally occurring radiation from cosmic rays and terrestrial rock strata. Food is commonly slightly radioactive because it absorbs naturally radioactive substances like Potassium-40 and Uranium.
Not to be confused with Background radiation without the Natural - this is a trick to write off man-made pollution spread around the environment.
Neutron An elementary particle with about the same mass as a proton but with no electric charge, present in all atomic nuclei except ordinary Hydrogen.
NRPB see National Radiological Protection Board
NORM Naturally Occurring Radioactive Materials
Nuclide A type of atom characterised by the number of protons and neutrons in the nucleus. In other words, it's any of the isotopes of an element.
OECD Oganisation for Economic Co-operation and Development
Public Health England See National Radiological Protection Board.
Rad = Radiation Absorbed Dose - an obsolete unit of absorbed dose now replaced by the Gray (q.v. and see Roentgen).
Radon (Rn.) A naturally-occurring radioactive but inert gas part of the decay chain that starts with Uranium and ends with lead. An alpha emitter with a half life of 3.2 days.
Since there is a lot of Uranium on the planet (about a hundred thousand billion tons) it is constantly producing considerable quantities of radon, which seeps out of the earth's crust and then we breathe it in. The resulting dose to our lungs is half of the total radiation we absorb, according to the nukes' favourite pie chart. This is one type of exposure where NRPB's averaging approach is valid, since radon is chemically and biologically inert; it doesn't concentrate or become localised anywhere, except where it becomes attached to particles. Epidemiological studies do not show that regional variations in radon are matched by variations in disease rates, but other pollutants do have an effect.
Radioactivity The spontaneous emission of energy from nuclei of unstable atoms.
Radionuclide Unstable nuclide capable of spontaneous transformation into an other nuclide by emitting photons or particles, thus changing its nuclear configuration or energy level.
RBE see Relative Biological Effectiveness and Dose Equivalent
Relative Biological Effectiveness (RBE) see Dose Equivalent
REM see Roentgen Equivalent Man
RERF Radiation Effects Research Foundation. See ABCC
Roentgen A quantity of radiation absorbed per unit mass of matter. Named after the man who discovered X-rays. Replaced by rads (radiation absorbed dose) where one Roentgen = 0.93 rad. It has now been replaced by the gray, where one gray equals 100 rads.
Roentgen Equivalent Man see "Dose Equivalent"
RWMAC Radioactive Waste Management Advisory Committee; a quango advising the UK government. RWMAC slavishly follows NRPB's view of the health effects of low levels of environmental pollution and is pressing for relaxation of disposal thresholds thus aligning itself with the IAEA and the Article 31 group of "experts" advising the European Commission.
SAHSU Small Areas Health Statistics Unit. Set up on the recommendation of the Black Committee to make sure that embarrassments like the Seascale leukeamia cluster were discovered by official bodies, rather than by news hounds. SAHSU has instead adopted a mission of making life easier for local authorities and health authorities by telling them that clusters are just part of the random distribution and that the causes can't be found. Based at Imperial College, London.
Sievert (Sv.) see Dose Equivalent
SMR Standardised Mortality Ratio (q.v.)
SoLA
[SoLA EO]
Substances of Low Activity Exemption Order. One of 17 Statutory Instruments which under UK law allow some practices involving radioactivity to be exempt from regulation under the Radioactive Substances Act [originally from the 1960 RSA but now its 1993 replacement]. The SoLA EO adopted a threshold value of 400Bq/Kg as the cut off. This was in 1986; no-one now knows why 400 Bq/Kg was chosen. The Order specifically included the disposal of wastes from Exempt undertakings. This has turned out to be crucial, since this EO is now being applied to the Clearance [q.v.] of unlimited amounts of "minimally" contaminated materials and even the delicensing of entire sites, thus allowing them to be sold off and used for housing, or anything, as if they were clean.
Standardised Mortality Ratio (SMR) Standardised Mortality Ratio; the rate of deaths relative to national average rates after adjustments have been made for the age structure and relative social status (or deprivation) of the study population. For example 1.31 means "1.31 times what you would expect on the basis of national averages for a (hypothetical) population with the same proportions of people aged 0 - 4 years, 5 - 9 years, and so on, and where the people have the same income levels, types of job, standards of housing, diet, smoking habits and so on as the area in the study." You could also call it "31% above average".
Stochastic effects An effect like cancer or other mutation which, following radiation exposure, may or may not occur in any particular person. In other words, it's a matter of probabilities.
Such effects do not vary in severity (you either have got cancer or you haven't - in just the same way that you can't be slightly pregnant), but they do vary in frequency in proportion to dose. The shape of the dose-response curve is, however, disputed - it's unlikely that effects are strictly proportional to dose (see bi-phasic) and, in any case, there are large problems with the concept of dose (q.v.). All low level radiation effects are essentially stochastic. At higher doses effects like radiation burns occur with a clear and well recognised relationship between dose and both frequency and severity. These are non-stochastic or deterministic. High doses may cause stochastic effects as well.
Stochastic comes from a Greek word meaning to guess, so it also describes NRPB's risk assessments.
Synergy The combination of factors which each multiply the effects of the other(s) rather than merely adding to them.
TENORM Technically Enhanced Naturally Occurring Radioactive Materials
Transuranic An element with atoms heavier than those of Uranium.
UNSCEAR United Nations Scientific Committee on the Effects of Atomic Radiation
URANIUM RATIOS The three natural isotopes of Uranium are U238 U235 and U234.
The isotopic percentages are, respectively, 99.2745/0.72/0.0055.
When organisations publish results of analysing environmental samples it is common to use the ratio of U238 to U235. To get their natural ratio we have to divide 99.2745 by 0.72 = 137.88. A number higher than 137.88 means there is less U235 than naturally occurs, indicating that Depleted Uranium (DU) has been used. A number lower than 137.88 indicates the presence of an unnaturally large proportion of U235 — i.e. it’s enriched. In practice it is usual to assume that ratios between 136 and 142 are inconclusive; ratios larger or smaller than these values are significant.
More detail and background information.
Wards In connection with epidemiological studies it has been pointed out to us that outside the British Isles the word "ward" is not well understood. Apologies for any confusion.
Wards are local administrative areas for the purpose of conducting elections and censuses. This usage is common in Britain and the USA.
In Britain each ward defines a population of about 2000 people. This is the smallest unit for which officially collected population statistics are commonly available. The figures are updated in censuses conducted every ten years since 1841 (or maybe earlier)
Urban wards cover small geographical areas, rural wards may be many square kilometers in extent.
Thus in small towns on the coast (there are many in Wales) the whole population lives near the sea (within a kilometer), but in rural coastal wards many of the people live distant from the sea.
The coastal towns in Wales next to the contaminated Irish Sea show the highest cancer and leukaemia risks and this difference in Relative Risks supports the hypothesis that the incidence of disease is driven by proximity to the sea and consequent exposure to inhaling the radioactivity that is migrating inland.
WCISU Welsh Cancer Intelligence and Surveillance Unit
WCR Wales Cancer Registry; one of a dozen or so cancer registries in England and Wales collecting cancer data from 1974. WCR was closed down in 1996 amid allegations of incompetence, shortly after releasing all its data to the Low Level Radiation Campaign. It was replaced by the Welsh Cancer Intelligence and Surveillance Unit.
WEERIE a computer programme for reactor safety analysis which, according to the blurb, " ... allows a comprehensive analysis of the consequences of radioactive releases discharged from nuclear installations to the atmosphere."
When used after the event it obviously spares NRPB the inconvenience of going out into the environment to measure what's really happening, and if you just feed in the wrong wind direction you can make complete nonsense of everything, as the big expert on the WEERIE programme - NRPB's Director Roger Clarke - did in 1974 [see this link] . There's lots of information on the web.


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