Ionizing radiation, radiation safety
Contents
| Name of issue | Time |
| Introduction. | 5' |
| 1. Ionizing radiation, radiation safety | 45' |
| 2. Electromagnetic field of radiation safety of EM radiation. | 35' |
| The final part. | 5' |
Literature.
1. Zaplatynsky V.M. Safety life. Backing lecture notes for all specialties. - K. KDTEU, 1999. - 208 p.
2. Bedrij J.I. , Safety life. Textbook. - L.: Magnolia-2006, 2007. - 499 p.
3. Zhelibo E.P, Zaverukha N.M., Zatsarnyy V.V. Safety life. Textbook/ By version Zhelibo E.P. 6th edition . - K.: Caravel, 2008. -344p.
4. Lapin V.M. Safety of human life. Textbook. - K.: Knowledge, 2007. - 332 p.
5. Law of Ukraine "On protection of population and territories from emergency situations of technogenic and natural character", 2000
6. Public hygiene standards. Radiation Safety Standards of Ukraine (NRBU - 97). (Ministry of Health of Ukraine from 14.07.97 № 208).
http://mozdocs.kiev.ua/view.php?id=2402
7. State sanitary rules and regulations when dealing with sources of electromagnetic fields. 3.3.6.096-2002. http://normativ.com.ua/ot/
8. Terms of safety in the operation of computers. http://normativ.com.ua/ot/ — (Regulations Gospromgornadzora Ukraine. Rules).
Tasks for independent work
1. Study material lectures.
2. Familiar with the governing documents [6-8].
TOPIC 4
RADIATION SAFETY, SECURITY ON ELECTROMAGNETIC WAVES.
Ionizing radiation, radiation safety
Electromagnetic field, their radiation, safety of EM radiation.
Introduction.
In the previous lecture we learned about harmful and dangerous factors of active group and how to protect from them. Notice, that person also protected VrF from using collective and individual protection and moving beyond the zone of danger. Also paid attention to NSHF human perception through physiological functioning analyzers of man. Notice, such SHNF as ionizing and Electromagnetic radiation is not to feel by a person in any physiological analyzer. Given the current radiation situation in Ukraine and the world, saturation equipment with electromagnetic radiation, your further professional career in information technology, Issues of radiation safety, safety of electromagnetic radiation become very relevant in the present days. Today we acquainted with the mechanisms and varieties of ionizing and electromagnetic radiation, with a mechanism of the harmful effects on the human body, with requirements regulations to ensure the safety of domestic and industrial conditions, the main methods of protection and workers from these SHNF.
Ionizing radiation, radiation safety
Ionizing radiation existed on Earth long before the appearance of human on it. However, the effect of ionizing radiation on the human body was detected only in the late XIX century by the opening of the French scientist A.Bekkerelya, then studies of Pierre and Marie Curie phenomenon of radioactivity.
The concept of "ionizing radiation" combines different types, different inherently radiation. Their similarity is that they all characterized by high energy, tend ionization and destroy biological objects.
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Ionizing radiation - is any radiation interaction with the environment which leads to the formation of different electric charges signs. There are corpuscular and electromagnetic (photon) ionizing radiation.
Corpuscular and electromagnetic radiation differ in terms of the formation and properties: wavelength and energy density.
By photon radiation belongs to ultraviolet radiation - the most short-wave part of the spectrum of sunlight (wavelength 400*10-9m).
Radiation characterized by its ionizing and penetrating capabilities.
Ionizing radiation is determined by the ability of specific ionization, ie, the number of ion pairs formed particle per unit volume or mass medium or per unit path length. Different types of radiation have different ionizing power.
Penetrating power of radiation is determined by the size of path, ie the path traversed by particle in matter to its complete disappearance.
Sources of ionizing radiation are divided into natural and man-made (anthropogenic).
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The radiation background generated by cosmic rays, gives less than half the external exposure that people receive from natural radiation sources. Exposure from natural sources of radiation exposed all the inhabitants of the Earth, but some of them receive higher doses, others - less. Radiation levels in Deycal occurrence of radioactive rocks of the globe significantly higher than average, and elsewhere - under lower. The dose of irradiation ion also depends on the lifestyle of people.
According to the Scientific Committee on the Effects of Atomic Radiation, United Nations, the average effective equivalent dose of external radiation that a person receives a year from terrestrial sources of natural radiation is about 350 mk3v, or slightly more than the average dose due to background radiation formed by cosmic rays.
Man undergoes radiation in two ways - external and internal.
External radiation. If radioactive substances are outside the body and lit it from the outside, in this case we deal with external radiation.
Internal radiation. If radioactive substances are in the air breathing person, or in food or water and get into the body through the respiratory and gastrointestinal tract, it is called internal radiation.
Internal irradiation is on average 2/3 of effective equivalent dose that a person receives from natural sources of radiation. It goes over from radioactive substances that get into the body through food, water or air. A small portion of the dose accounted for radioactive isotopes (such as carbon-14, tritium), formed under the influence of cosmic radiation. Everything else comes from sources of terrestrial origin. The average person receives about 180 mkZv/year by potassium-40, which is digested with not radioactive isotope of potassium, which is essential for human life. However, a much larger internal dose a person receives from radioactive nuclides of uranium-238 and lesser number of radio nuclides number of thorium-232.
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Artificial sources of ionizing radiation are nuclear explosions, nuclear facilities for energy production, nuclear reactors, particle accelerators, X-ray machines, devices communications equipment, high voltage, etc.
Damaging factors are:
1. Penetrating radiation.
2. Radioactive pollution areas (Radioactive pollution - the presence or spread of radioactive substances over their natural content in the environment and / or in the human body).
Over the last few decades mankind created hundreds of artificial radionuclide and learned to use energy of the atom in military purposes-for manufacturing of WMD, and in peaceful – for producing of energy, in medicine, for searching of minerals, diagnostic equipment and others. All this causes the increasing of exposure portions for separate people, and for the whole Earth population.
Individual doses, which are obtained by different people from ionizing radiation, are strongly different. In most of the cases this doses aren’t significant, but sometimes radiation of the technogenic sources in many thousands times intensive than because of natural. However, it should be noted that radiation which was made by technogenic sources of radiation is easier to control, than the radiation caused by cosmic and earth natural sources.
The radiation of the population of Ukraine in the last years by artificial sources is mainly connected with the results of disaster on Chernobyl AES. Among the technogenic sources of ionizing radiation as for today, people mostly radiated during medical procedures and treatment, connected with the usage of radioactivity, sources of radiation.
Among the different types of ionizing radiation, as was mentioned above, most important in terms of considering the question of life safety and health, are the radiation which appears as the result of decay of nuclei of radioactive elements, so to say ionizing radiation.
In contradistinction to penetrating radiation, (the flow of neurons and gamma-quantum) radioactive infection of the locality acts long time (months, years, decades).
The mechanism and character of infection in nuclei explosion and during the catastrophe at nuclei reactor have the same and different signs (Table 1).
The grade of radioactive poisoning as the result of disaster on nuclei reactor is determined by amount of radioactive parts, which come into atmosphere because of their release from reactor. The amount and radionuclide composition of release from destroyed reactor depends on the character of destruction, the power of reactor, the regime of overloading of fuel and time which last from last overloading.
Radioactive dust, which hit to the atmosphere, settles after time, infect big areas of territories and all objects placed on it, and result is the radioactive cloud on the way of motion of which the radioactive trace appears- infection zone. In this process N of infection = 0.5% N of release. Lets point that zone of radioactive infection appeared as result of disaster on nuclei reactor will be characterized in comparison with the same case of nuclei explosion, by less area of the territory with dangerous dose of radiation, however its geometrical parameters are greater and it can reach hundreds or even thousands kilometers. The lowering of radiation level in this process occurs more slowly and the law of decline is:
X*t0.5=const (1)
Table 1
| № | Feature | Reactor accident | Nuclear explosion |
| Similarity | |||
| Effects of ionizing radiation on 2-3 km. | |||
| Radioactive contamination - large areas | |||
| Requires uniform set of measures | |||
| The presence of lesions of humans, animals, plants, water, soil | |||
| Difference | |||
| І | Nuclear chain reaction | there is not | there is |
| type of explosion | vapor | nuclear | |
| Height radioactive cloud | <4-6 km | < 18-20 km | |
| 4 | Time loss of radioactive substances in a particular area | > 1 day | to 1 hour. |
| The nature of radioactive contamination | spotted | in the form of an ellipse | |
| Number of radionuclides | to 400 | to 200 | |
| The decline in radiation levels or does it mean that because | Dt t - 0.5 = const Dt= D1 t - 0.5 4 day Din 10 times [t] = hour. [D] = Р/h. | Dt t - 1.2 = const Dt= D1 t - 1.2 after 7hour. D in 10 times 72h.(2 day.) – at 100 times 73 h.(2week.) – at1000 times |
It is explained by that in a reactor mos radionuclides is formed long before its destruction and the relative availability of short-lived radionuclides it will be much lower compared with the products of a nuclear explosion. So when people live in such areas and uselocal food production should take into account not only the effect external gamma radiation, but also revenues biohazard radionuclides in the food chain, as well as inhalation of contaminated air.
Radionuclides form of radiation at the moment, converting one atomic nuclei in others.
They are characterized by:
- Half-life (from 1 sec. till million years), Half Life - Characteristic of radionuclide - the time during which the number of nuclei Radionuclide result of spontaneous nuclear transformations reduced by half.
- Activity (number of radioactive transformations per unit time) that characterizes their ionizing ability. Activity in the International System (SI) is measured in Becquerel (Bq), and сommon unit is the Curie (Cu). One Cu = 3,7 х 1010БкBk.
The measure ionizing radiation, in any environment depends the energy of the radiation and the estimated dose of ionizing radiation. The dose is determined for air, material and biological tissue. Accordingly distinguish:
1. Exposure dose IP.
2. Absorbed dose IP.
3. The equivalent dose of IP.
Exposure dose characterizes ionizing radiation power in the air is measured in coulone per 1 kg (C / kg) Common Units - X -ray (R), 1 C / kg = 3.88 x 103R. For exposition dose can be determined potential of ionizing radiation. (1 R - a dose at which at 1sm in cube created 2.1 * 109 ions).
Absorbed dose characterizes the energy of ionizing radiation absorbed by unit mass of irradiated material. It is measured in hreyah Gy (December 1 = 1 J / kg). Applies Common Units and tips (1 rad = 0.01 = 0.01 December J / kg).
Dose that person receives depends on the type of radiation, the energy flux density and duration of exposure.
Equivalent dose is a measure of the biological effects of radiation to a specific person, that individual criterion danger brings about lenym ionizing radiation. The unit of measurement equivalent dose received sievert (Sv). Sievert is devoured a dose of 1 J / kg (for X and α, β, radiation). Common Units is the rem (biological equivalent Board). March 1 Sv = 0.01.
Table D.10.2 - Relationship between Common and units in the Cl
| Quantity | Old unit | New unit | Conversion coefficient | ||
| Cl out sys | Out sys in Cl | Conversion | |||
| Activity | Curie (Ci) | Becquerel 1Bq=1 s-1 | -2,7.10-11 | 3,7.1010 | 1 Cі=3,7.1010Bq 1 Bq= 2,7.10-11Ci |
| Total activity | Ci/g Eman Mache Tritium unit | Bq/kg Bq/l Bq/l Bq/l | -2,7.10-14 -2,7.10-1 -7,4.10-2 -8,3 | 3,7.1013 3,7 13,5 1,2.10-1 | 1 Cі/g=3,7.1013 Bq/kg |
| Pollution density | Ci/km2 | Bq/m2 | -2,7.10-6 | 3,7.104 | Ci/km2 = 2,7.10-6 Bq/m2 |
| Exposure dose | Roentgen (Р) | Coulomb per kg C/kg | 3,9.103 | 2,6.10-4 | 1 Р=2,58.10-4C/kg 1 C/kg=3,876.103 Р |
| Absorbed dose | Rad | Gray 1Gy=J/kg | 1.102 | 1.10-2 | 1Gy=J/kg 1 Gy= 100 rad |
| Equivalent dose | Rad’s biological equivalent (rem) | Sievert 1Sv =J/kg | 1.102 | 1.10-2 | 1 Sv =J/kg 1 Sv = 100 rem |
| Effective dose | Rad’s biological equivalent (rem) | Sievert 1Sv =J/kg | 1.102 | 1.10-2 | 1 Sv =J/kg 1 Sv = 100 rem |
Under the influence of ionization radiation, atoms and molecules are ionized by living cells, resulting undergoing complex physical and chemical processes that influence the nature of future human life.
1) According to some views, the ionization of atoms and molecules, which occurs under the influence of radiation, leading to the cancellation of bonds in protein molecules, leading to cell death and destruction of the body. Form compounds which are not typical living organism. This leads to metabolic abnormalities, enzyme inhibition and specific functional systems, ie violation of life of the whole organism.
2) Specificity of ionizing radiation is that the intensity of chemical reactions induced by free radicals increases, and they involved many hundreds or thousands of molecules not affected by irradiation. Thus, the effect of ionizing radiation, caused not by the number of absorbed energy target and form in which this energy is transferred. No other form of energy (heat, electricity, etc.). Absorbed by biological objects in the same amount, does not lead to such changes, which leads to ionizing radiation.
Also to be noted some peculiarities of ionizing radiation on the human body:
• senses do not respond to radiation;
• small doses of radiation can add up and accumulate in the body (cumulative effect);
• radiation affects not only the present living organism, but also to his heirs (genetic effect);
• various organs of the body have different sensitivity to radiation.
The strongest effect is experienced by the cells of red bone marrow, thyroid, lungs, internal organs, ie organs, cells that have a high level of division. At one and the same dose of radiation in children affects more cells than in adults because children all the cells are in a state of division.
The effects of ionizing radiation (radiation) are classified and systematized by types of damages and time display.
By damages are divided into three groups:
1) physical,
2) somatic (random, probable)
3) genetic.
By the time display into two groups - early and late.
Early lesions are only physical. This leads to the death or radiation sickness. Suppliers of such particles are mainly isotopes with a short lifetime, γ-radiation, neutron flux.
The acute form occurs as a result of exposure to higher doses for short time. At doses of the order of thousands of boards lesion body can be instantaneous. The chronic form develops result from prolonged radiation dose that exceeds limyty dose. To address issues of radiation safety first cause interest effects observed at low doses of irradiation-reference sample- The order of several santyzyvertiv per hour, which actually happens with- yutsya the practical use of nuclear energy. In a normal radiotion Security NRBU-97, introduced in 1998 as a unit of time used tovuyetsya-year or the concept of annual dose. This is, as noted earlier, effect of the accumulation of "small" doses and their Sumartion effects on the body person.
There are various rules contamination: single, accompanied useless maximum allowable, and more. These are described in specific directories.
LD total human exposure dose is considered that in the current Knowledge should not cause serious damage to the body over a lifetime.
HDD for people who are constantly working with radioactive substances-us is 2 rem per year. If this dose is not observed somatych-tion lesions but still fairly unknown how implemented carcinogenic and Genetic effects of actions. This dose should be considered as an upper limit, which is should converge.
Radiation safety.
Radiation safety - state radiation and nuclear facilities and environmental environment that provides for avoiding the basic dose limits exclude any undue exposure and dose reduction exposure of personnel and the population below the dose limits extent this can be achieved and economically justified.
Radiation weighing factor - a factor that takes into account the relative biological effectiveness of different types of ionizing radiation. Used when calculating the effective and equivalent doses.
Using the concept of risk in the practice of radiation protection rights
Limits exposure of the population and personnel (including the dose with the planned increased irradiation) are set based on the scale of risks due to any likelihood of adverse effects in practical activities related to the action or use of ionizing radiation can be correlated with the probability loss of health or life in other areas not related to the radiation factor.
Using the value of risk operate such concepts as rejected risk, acceptable risk and the upper limit of individual risk. In accordance with international practice in NRBU-97 accepted:
| Rзн=10-6 | neglected risk |
| Rпр(А)=10-4 | acceptable risk to personnel |
| Rпр(В)=10-5 | acceptable risk for the population |
| Rінд(А)=10-3 | upper limit individual risk for personnel |
| Rінд(В)=5*10-5 | upper limit individual risk for the population |
The concept of risk is valued for both the stochastic and deterministic effects.
Individual (r) and collective (R) - risk of stochastic effect appearance of radiation is determined in accordance with:
r = rЕ х E
R = гЕ х ЕS,
where E, Es - individual and collective dozes, accordingly;
re - risk coefficient of cancer with fatal and nonfatal outcome, and serious hereditary effects.
Risk coefficient per unit of individual or collective doze (in accordance with appendix 1 point 4 НРБУ-97 ) accepted as equal to:
rЕ = 5,6*10-2 Зв-1 - for professional radiation
rЕ = 7,3*10-2 Зв-1 - for population
Risk of heavy effects is equal to the probability of an accident appearance at radiation in dozes that cause deterministic effects:
r = p(E)
R = p(ЕS) х N,
where P(E), P(ЕS) - probability of events, which create dozes E and ЕS;
N - amount of population that was influenced by equivalent dozes of radiation E > 0,5 Зв.
Optimization principe is one of the principles for providing radiation safety, which implies decrease of risks to the minimum level and provides in a range from the upper to lower limit that is defined as a rejected risk and below of this lower limit, limit decrease is appropriate.
R is [Rн, Rв], Rн=Rзн.
Optimization principe is done considering that risk limit regulates potential radiation from all possible sources, that's why for each source in optimization process there is its own risk limit.
Dozes reduction below the lower limit is connected with additional expenditures for protection. Expenditures is considered to be justified if following condition deals:
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where V - monetary expression of the gross (full) profits earned as a result of industrial activity;
P - cost of primary production;
X - cost of protection;
N - number of radiated individuals;
λ - cash equivalent unit risk
Cash equivalent unit risk quantity is calculated from gross domestic product quantity for one citizen (economic of a component) and with counting of psychological risk perception compensation (psychological or social of a component). Usually, economic of a component is 5-10 % of psychological one in practice of protection optimization.
Radiation safety measures used in the business and how usually require in carrying out a complex variety of protective activities, depending on the specific conditions of work with sources of ionizing radiation and, above all, on the type of radiation source.
Protective measures to ensure radiation safety conditions, based on the knowledge of the spread of radiation and the nature of their interaction with matter. The main ones are:
> external exposure dose is proportional to the radiation intensity and exposure time;
> intensity of radiation from a point source is proportional number of photons, or particles that occur in it per unit time, and inverse proportional to the square of the distance;
> intensity can be reduced by screens.
These regularities follow the basic principles of Radiation Safety:
- Reduce power sources to the minimum ("protection number ");
- Reduction running time of the source ("protection time");
- Increasing the distance from the source to the people ("protection of distance");
- Sources of radiation shielding materials that absorb ionizing radiation ("protection screen").
The basic principles for the protection of open sources of radiation:
> using protection principles that apply when working with sources of radiation in a closed form;
>sealing of production equipment to isolate processes can become sources of radioactive substances in the outer environment;
> Events planning nature;
> Use of sanitary means and equipment, use of special protective material;
> using of personal protective equipment and sanitization personnel;
> Personal hygiene;
> Treatment of radioactive contamination of surfaces of building structures, equipment and personal protective equipment (decontamination);
> using radio protectors (biological protection).