Protective measures of the staff and population.

The basic principles of the prevention of radiating affects are the following: usage of materials protecting from radiation, reduction of time of an irradiation, increase of distance from a source of radiation, usage of means of medicines protection.

One of the most difficult questions is a question of acceptance of protective measures among the population in a zone of distribution of radioactive emission products. Many protective measures are connected with known risk for health of the people conducting these measures, and with significant social costs to the population. The realization of such measures as evacuation, territory decontamination, cattle transportation for feeding by beforehand prepared fodder is connected also with material expenses, with economic losses from cessation of work of the enterprises, closing of pastures, exception of usage of fields, destruction of the polluted products and so on, as well as with moral damage owing to necessity to abandon native places, dissociation of families etc. Therefore in МКРЗ opinion the protective measures should be commissioned only when their social cost and risk will appear less, than those from the further irradiation.

The basic doze limits are certain for various groups: for the persons working with sources of radiation (category "A") - 50 mZv/year, for the persons living near to sources of radiation (category "B”) - 5 mZv/year, for other population (category "C") - below 0,5 mZv/year.

The decision on acceptance of the certain protective measures will be accepted mostly depending on forecasted doze level. A degree of risk, difficulty of infringement of vital activity and other undesirable consequences are various after introduction of various protective measures. And so the estimation of all these consequences influences on an establishment of a level of dozes, at which these or those measures are required. It is necessary to determine the top doze level at which the introduction of a considered protective measure is almost necessary, and the level, below which the introduction of the given measure is not justified.

The protective measures at dozes less than “B” category are not advisable. In a range of dozes between these two levels the decision about the necessity of realization of this or that protective measure is accepted depending on conditions.

Some orientation concerning expected dozes, at which the introduction of protective measures is advisable, can be obtained from following recommendations of МКРЗ: for evacuation and resettlement the top level of a doze is 500 mZv, lower - 50 mZv. For shelter, intake of stable iodine, control of foodstuff the top level of a doze is 50 mZv, lower - 5 mZv.

The levels of influence allow to estimate (according to these criteria) the correctness of application of an emergency protective measures connected to infringement of normal ability to live of the population. If the radiation or contamination does not exceed the lower level, it isn’t necessary to realize such measures. At achievement of the top level all measures of protection must be engaged.

To organize a service of radiation safety and performance of all volume of protective measures adequate for each particular period of time after the accident, it is necessary to allocate three consecutive stages of an accident development:

The initial stage – is the period of threat of emission of radioactive substances in an environment and the first hours after emission;

Stage of primary liquidation of consequences of failures – is the period from the first several days up to one month, when it is supposed, that the greater amount of emission has already happened and radionuclides have already fallen on the ground;

The stage of realization and end of works on liquidation of failure - in this period the decontamination of territory of station and environmental district is coming to the end, the repair work on a place of failure is finished, the complex of hygienic measures on polluted territories will be carried out, the decisions on realization of agricultural works are accepted.

These stages are general for all failures with emission of radioactive substances in an environment and cover a period of time from a beginning of failure to the end of works on its liquidation.

The initial stage. The acceptance of the decisions on the initial stage about preventive and protective measures is based, mainly, on the information obtained from NPP. There are two methods for operative forecasting of the absorbed dozes, which will arise at emergency emission.

First method consists in a theoretical estimation of size and character of radioactive emission at the initial stage of failure. This estimation of dozes is necessary to conduct on the basis of the information received from NPP and taking into account the meteorological observation.

The second method is the measurement of radionuclides activity (density of pollution and isotope structure) outside a place of failure soon after a beginning of emission into environment (it is necessary to obtain these data as soon as possible). The results of such measurements will confirm or correct theoretical accounts carried out earlier and will allow to estimate more precisely the radiating conditions in those areas, where the measurements were carried out. Dosimetric measurements should be carried out by specialists, equipped by the appropriate technique. These groups should begin their work immediately. Depending on the sizes of emission and possible dozes of radiation the shelter of the population will be carried out. The usage of shelters includes also staying of the people in their homes at the closed windows. Thus it is expedient to caulk cracks of doors and windows by a wet paper or fabric. The walls of a stone house can lower the doze power on one degree. In Pripyat, which is located in several kilometers from Chernobyl NPP, in apartments, where the windows and window leaves were closed during all period of failure, there was not marked the significant radioactive pollution of the things. It is recommended to use the improvised means of protection of respiratory organs. It is possible to ensure protection of respiratory organs by usage of such simply means, as handkerchiefs, towels, cotton fabrics, pieces of clothes, by which the mouth and nostrils can be covered. The protective efficiency of these materials can be increased by their wetting. The individual special means of protection of respiratory organs (respirators, gas masks etc.) are obligatory for special groups participating in operations on liquidation of failure. The protection of a body is reduced to protection of a skin and hair, what is possible to ensure with any pieces of clothes, including hats, jackets, raincoats, gloves, boots etc. It is necessary to follow these recommendations. So, the patients who have arrived form Chernobyl NPP to the hospital, had extensive burns caused by radiation, except for places protected by dense clothes, boots, belt. The hair at surveyed was not polluted, if they were closed by hats, etc. The personnel participating in liquidation of failure, should use more complex means of individual protection (isolate suits). It is necessary to avoid long movement on the polluted territory - on a dusty road, grass. In an initial period the emergency preventive measures to avoid the affect by radioactive iodine should be carried out. The emergency " iodine preventive maintenance " begins only after the special notification and should begin as soon as possible (!). The emergency " iodine preventive maintenance " is carried out immediately by organs and establishment of public health services at threat of pollution by radioactive iodine. To prevent the radiating influence of iodine radioisotopes the preparations of stable iodine are used, which extremely effectively warn the accumulation of radioisotopes in the thyroid gland and promotes their removing from organism. For iodine preventive maintenance the tablets of potassium iodine are used, and at its absence – the water-spirituous iodine solution is used. The potassium iodine is applied in tablets, in dozes of 125 mg, for children above two years and adults, and for children under 2 years - 40 mg after meal together with jelly, tea, water 1 time per day for 7 days. Thus practically the 100 % degree of protection is reached.

The water-spirituous iodine solution (5%) is applied to children above 2 years and adults 3 times per day for 7 days (3-5 drops on a glass of milk or water after meal). Thus practically 100 % degree of protection is achieved. The milk should be obviously clean - not to contain iodine isotopes (bought before the accident, tinned). 5 % iodine tincture is applied to children under two years 1-2 drops on 100 ml of milk or nutritious mix 3 times per day for 7 days. At danger of radioactive iodine isotopes receipt into the organism the pregnant women are recommended to intake potassium iodine, simultaneously with potassium perchlorate once per day (125 mg potassium iodine and 750 mg potassium perchlorate). They are taken after meal, washed down by sweet tea, sour milk. The tablets should be taken until the elimination of direct threat of radioactive iodine isotopes receipt (but not more than for 7 days). Potassium perchlorate, taken simultaneously with potassium iodine, weakens the toxic influence of potassium iodine on the fetus.

The major moment of planning the emergency measures is the opportunity of the fast notification of groups of the people, which can undergo or already have undergone the irradiation. The purpose of the notification is to achieve the peoples’ staying in rooms (buildings). It is simple and effective measures of protection at cooling a torch of emission of radioactive substances. The doze of an external irradiation thus depending on a type and size of a building is reduced in 2-10 times. Closing of windows and doors and deenergizing of ventilation will lower a doze of an irradiation from RS inhalation and superficial pollution.

After passage of a torch of emission the urgent notification about necessity to close windows and to switch off ventilation is required. Besides the application of elementary respirators and simple breathing through a wet fabric can lower a doze of RS inhalation receipt in 10 times. Iodine preventive maintenance must be carried out under the control of a medical service, since the superfluous iodine application can cause undesirable consequences.

The evacuation is one of the most difficult measures, by its organizing, and also by breaking the vital activity. If there is enough time, the anticipatory evacuation can exclude or strongly decrease the radiation of the population. The difficulty of acceptance of the decision about evacuation at an early stage depends on complexity of a situation, whether the danger of consequences of a potential irradiation is so high to justify all undesirable consequences of introduction of this measure, taking into account uncertainty in a prediction of the further development of events in the reactor, forecasting of dozes of an irradiation and territory contamination.

The evacuation requires time and at an early stage is carried out only on short distance. Evacuation should be taken before appearance of a torch of radioactive substances. The dozes can be much higher if people are not under the shelters.

Individual decontamination is necessary in cases of revealed or supposed skin contamination - it is recommended to take off clothes, carefully and thoroughly wash up hands, face, hair, to take a shower, using ordinary soap, washing powders or specially developed washing powder "Protection".

The first aid brigades render the first aid at early stage of accident, which includes a call away of victims out of zone of an industrial platform; realization of sanitary processing and transportation of injured with initial reaction to the nearest medical establishment. In the shortest terms the specialized radiological-therapeutic brigade should begin work which carries out survey of all possible victims, fills in out-patient cards, carries out sorting and directs all persons with suspicion of ARD II-IV degrees of severity to specialized in-patient departments.

The stage of initial liquidation of failure. At this stage the basic problem is the radioactive pollution of territory and objects. If the emission of radioactive substances proceeds, so all factors of influence preserve. Depending on conditions, in this period the following measures are possible:

- temporary migration from areas where the doze is not so high but rather considerable. However the evacuation is not needed;

- control of foodstuff and water. The estimation of J131activity in milk is most essential, it reaches a maximum in 2 days after single emission. Therefore the decision on using it should be accepted as soon as possible. The power of a doze lower than 50 mcR/h is accepted as a parameter which is not requiring departure of products for exacter radiometric or radiochemical researches. The doze of an internal irradiation from such product will not exceed 0,05 Zv annually.

- the usage of the prepared forages for an animal. The sooner the cows will be removed from pastures and are set on the usage of prepared forages, the lower will be a level of milk infection.

- sanitary processing of the people, which were exposed to radioactive pollution.

- medical help, though it is not much needed. The treatment will be carried out by general principles of ARD treatment. If necessary then the RS removing measures take place.

At the recovering stage the measures ensuring returning to normal life will be carried out. At this time the decontamination works, fixation of pollution, establishment of barriers for prevention of RS moving are carried out.

At all stages of liquidation of failure the movement of the people through border of the polluted territory is limited. This measure is directed on restriction of pollution distribution and on prevention of the unjustified irradiation.

The existence of radiation lesions in the contingent, who carry out the work on the contamination territory, is achieved by reducing the radiation doze. During the work the maximum permissible dozes are set for a concrete case. The daily doze of an irradiation is usually accepted to be 0,01 Zv.

The duration of work in conditions of an external irradiation is limited in view of levels of radiation and established limiting daily doze. Thus the doze which can be received in a place of a constant arrangement and during delivery to a place of work is taken into account. Along with all this an individual dosimetric control of the really received doze is carried out, the results of which are registered in journals and personal cards.

For protection from external and internal radioactive contamination the individual means of protection are used, such as protective suits, gloves, boots, respirators and gas masks. The usage of protection means of single use is preferable. Decontamination, water and special laundries are used as means of protection. According to НРБ-76/87 the pollution of personal clothes and underwear by b-active nuclides should not exceed 100 particles/cm² per minute.

Protective measures from damaging affect of ionising radiation

Physical protection.

The idealist and most reliable protection against damaging action of radiation is the so-called physical protection, which is provided with the appropriate constructive and technical ways. The physical protection sharply reduces a level of radiating influence on human organism. The ability of a material to reduce the action of gamma-radiation is usually estimated by a layer of half-weaken of radiation.

One layer of half-weakening the doze power (radiation intensity) reduces on 50%, two layers on 75 %, three on 87,5%.

Medical protection.

In some cases, when the irradiation of the people in exceeding dozes is inevitable the medical protection should be carried out. Here belongs: the pharmacological, biological, local protection of radiosensitive organs and tissues (their combination is possible).

As a result of the numerous researches the substances were found which when being entered into the organism for the certain time before the irradiation, can reduce to some extent the damaging effect of radiation.

Chemical protection on the warm-blooded for the first time was carried out in 1949 by Patt et al. They have shown, that the introduction of cystein, glutathione and sodium cyanide to an animal before an irradiation rendered protective action.

The weakening of damaging action of radiation occurs in conditions of oxygen insufficiency in cells or tissues at the moment of an irradiation, and the increase of the contents of oxygen strengthens this action. The downturn of sensitivity to radiation appears identical irrespective of the fact which the way and than causes a lack of oxygen in cells at the moment of an irradiation: by nitrogen, helium, argon or hydrogen, constraining of blood vessel in an irradiated site, oppression of the respiratory centre, blocking of hemoglobin by methemoglobinformation, blocking or weakening of tissue respiration.

On the basis of the mechanism of protective action the following processes can lay:

• Competition for strong oxidizers and free radicals formed as a result of water radiolysis;

• The increasing amount of the endogenic thiol junctions in tissues

• The development of mixed disulfides and convertible temporary junctions of them;

• The development of temporary convertible junctions with sensitive groups of vital enzymes or other protein molecules ensuring protection against damaging action at the moment of an irradiation;

• The migration of energy surplus with from macromolecules to radioprotector;

• The inhibition of the chain reaction of oxidation;

• The absorption of secondary ultra-violet radiation stimulating macromolecules such as nucleic acids;

• The increase of stability and mobility of protective mechanisms of the organism;

• The oppression of metabolism;

• Detoxicity or acceleration of removing the toxins from irradiated organism etc.

Radioprotectors should be highly effective and non-toxic, they should not cause decrease and loss of work capacity.

All existing preparations on their special-purpose designation can serve for protection from a short-term irradiation and high-power dozes, from prolonged irradiation and low power dozes raising the organism’ stability to radiation or X-ray therapy.

Biological protection.

In contrast with radioprotectors some medicinal preparations, having not specific action, are capable to raise general resistibility of organism and in particular to radiation. These substances have received the name of adaptogenes. Adaptogenes in contrast with radioprotectors render anti-radiation effect only at repeated introduction before some days or weeks and if the radiation is not lethal. The means of biological protection promote efficiency of complex therapy of radiation sickness, and also raise radioprotective effect of pharmacological and local protection. There are practically no contra-indications for means of biological protection and they can be used in any conditions. Here belong some microelements (calcium, Fluor), adenosinetriphosphate, dibazol, eleuterococcus, ginseng, Schizander chinensis, vitamin-aminoacid complex. The adaptogenes weaken morphological and biochemical displays of stress reaction.

The indication to realization of medical measures is the detection of radionuclides in organism. At detection in environment radioactive iodine and strontium - it is necessary to saturate an organism by accordingly preparations of stable iodine and calcium, at reception of radioactive cesium into an organism – the ferrocyne is applied, for acceleration of removing of cerium, plutonium and transplutonium elements from organism the pentacyne is applied. Usually these preparations are applied within two weeks.

The organization of the medical help to victims at failures on radiation-dangerous objects.

The character of therapeutic pathology at failures and accidents of peacetime (reactor failure, epidemic flares, HATA affects etc.) is much common with battle therapeutic trauma.

The experience of organization of the medical help to victims on Chernobyl NPP testifies, that pre-medical and the first medical aid were given by the nurses of NPP medical post and brigades of the first aid from 0,5 to 3-4 hours after failure. It consisted in taking out the victims from the industrial platform, partial sanitary processing, introduction antiemetic others symptomatic means, evacuation of the persons with the expressed primary radiation sickness. The persons with satisfactory state of health were invited for inspection to a medico-sanitary department at the first 12-24 hours. In 12 hours the specialized brigade has arrived in a zone of accident, which has examined 350 people for 36 hours, has made about 1000 analyses of blood. Per the first 3 day there was hospitalized about 300 people and during the next days about 200.

The medical establishments, sent to the accident zone, should be amplified by therapeutic-radiological and hematological groups or brigades. They are equipped by the necessary cure-and-diagnostic equipment, medical radiation monitoring instruments, means of early therapy and cupping of primary beam reaction, means of individual dosimetry, skin and breath organs’ protection means. Before an entrance to a zone of radioactive pollution the preparations of stable iodine are introduced.

The medical sorting will be carried out for the purpose of definition of realization necessity of special (sanitary) processing, promptness and volume of the medical help, way of evacuation.

The basic criteria of an establishment of a degree of severity of acute radiation disease (ARD) are: term of occurrence and degree of display of a nausea, vomiting, primary erythema, lymphopenia lower than 1*10⁹/l per the first day after an irradiation.

The leucocytosis level of more than 10-12*10⁹/l testifies a heavy and heaviest degree of ARD. The confused consciousness, febrile temperature, diarrhea, extremely high indices of radiation above a body surface (more than 1 R/hour) – is the characteristic for IV degree of ARD.

To a category of the persons who require the urgent medical help during initial reaction belong victims with III-IV degree of ARD severity (with unrestrained vomiting, collapse, widespread radiation burns, expressed intoxication).

To the persons, the help with which during primary reaction can be deferred it is necessary to carry struck with ARD I-II degrees of weight.

The victims with a doze of radiation not exceeding 1 Gr, in this period, as a rule, do not require the medical help.

The evacuation-transport sorting of affected supposes, that people are transportable after the cupping of vomiting and taken out of collapse with ARD of III-IV degrees of severity during initial reaction.

Thus, at large accidents with destruction of the reactor and radioactive pollution of an atmosphere and area it is necessary to expect mass radiating affects of combined character from external, internal both local g- and b-irradiation. The widespread radiation burns of a skin in many cases will determine the outcome of ARD.

The most difficult questions are:

• Duly and qualitative realization of medical sorting with allocation of a flow of the persons who have received an irradiation less 1 Gr,

• Rendering of the urgent help at vomiting and collapse,

• Realization of complete sanitary processing,

• The subsequent evacuation by air transport to the specialized medical establishments.