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43
y^K 504
RESEARCH OF THE RADIO-ACTIVITY OF MULTICOMPONENT
CONCRETES
А. Piven, student, E. Khоbоtоvа, d.ch.s., prof., E. Voronova, ass. prof.,
KhNAHU
Abstract. In this article the necessity of radiotional — hygienic estimation of multicomponent concretes is described. The expediency of experimental gamma-spectrometer as a method of research is shown. Effective specific activity of natural radionuclides are indicated in concrete and admissible borders of a specific radio-activity of cement in concrete structures. The value of gamma irradiation dozes of people is calculated due to the gamma-radiation natural radionuclides.
Key words: natural radionuclides, gamma-spectrometer, gamma-background, specific activity, concrete, gamma-radiation.
Introduction
Natural sources of the ionizing radiation contribute greatly to a doze of irradiation of the population. From all natural sources of irradiation a human being receives on average an equivalent doze constituting 2,4 milliSv a year-1. Among all natural sources of the ionizing radiation the leading place is occupied by the components of the radiating background of premises: 223>226Ra, 232Th, 238U, 210Po, 210Pb, 22a222Rn, 40K. The population of industrially developed countries spend about 80 percent of time inside the inhabited and industrial premises. The doze of natural sources of the ionizing radiation is influenced significally by natural radionuclides which are contained in building materials and also depend on peculiarities of construction of buildings.
The estimation of main radiation characteristics of multicomponent concretes
The purpose of the work is the research of radioactive properties of multicomponent concretes of the East region of Ukraine and calculation of the doze of gamma irradiations of the population in premises.
The industrial wastes are used for production of construction materials concentrating natural radionuclides. The specific activity here is typical for the concrete with fly ash, quartz shale, slag concrete, pumice concrete.
The specific activity of natural radionuclides in construction materials is the parameter defining the level of gamma-background in premises. For the definition of the specific activities of radionuclides
the gamma - spectrometer method with the semiconductor detector have been used. The presence of
natural radionuclides in 226Ra, 232Th, 40K concretes
samples have been revealed.
The specific activities of natural radio nuclides concrete samples have been got experimentally. The analysis of data shows that the specific radio-activity of concrete samples ranges from 84,1 up to 1043,4 Bq kg-1. Specific activity of some concrete samples exceeds the specific activity of concrete samples in the USA, Hungary and Germany (211-411 Bq kg-1). The effective specific activity (Cef) of natural radionuclides is counted by the formula
Cf = CRa +1,31Cra + 0,085Q
All investigated concrete samples refer to the first class of radiation danger of construction materials to be used in construction without restrictions. The condition [1] Cef < 370 Bq kg-1 should satisfy them.
The value Cef considerably exceeds the average one
by CIS (93 Bq kg-1) and in Ukraine (106 Bq kg-1) for concrete samples [2].
The specific activity of a cement component in concrete is calculated by the formula
Cf -Z nC
Ccem =---------!------ , Bq kg-1
n
cem
The value considerably exceeds the average one CIS (65 Bq kg-1) for concrete samples. The use of such concrete can lead to increase in the doze of the irradiation of people due to the increase of the
average effective specific activity Cef of ready
multicomponent concrete taking into accorent the mass contributions of its components.
The value of the annual effective equivalent doze of gamma irradiation ( Dquarters ) is calculated by the following formula [2]
Dquarters = 4,74C/ , microSv a year-1
where Dquarlers is the annual effective equivalent
doze of gamma irradiation, microSv a year-1. The formula deduded from the estimation of NKDAR U.N.O that people of living in industrially developed countries spend more than 80 % their time premises.
The value of the doze of gamma-radiation natural radionuclides concrete is calculated by the formula [2]
ADNRN = Dquar,ers - 305 - microSv a y^
where 305 is microSv a year-1 (the doze which people can receive being all the year round into the open district) [2].
The value of the annual equivalent doze of gamma irradiation ( Dod ), under the stipulation accoding to which people were found all the time running in the open district is calculated by the formula
Dod = 3,28Ce/, microSv a year-1 Thus, the difference
ADquarters = Dquarters - Dod = 298,96 microSv a yea^
representes the complemented action of gamma irradiation natural radionuclides resulting from postulate that people live in stone building. The results of calculations show, that Dquarters is rather
greater and depends on Cef the cement component
very little, and basically is defined by the activity of gravel rubble. In the category of houses constructed of the above mentioned concrete with the use of granite gravel rubble, as a filler of concrete,it is noted the highest doze of capacity. The increase of specific activity of natural radionuclides in gravel causes the increased level of gamma-background in houses of the above mentioned concrete.
The greatest values of dozes for the first and third variants, the contribution of gravel constitute 65-55 percent. In both cases the exceeded average value Dnrn in the CIS is 100 microSv a year-1 [2]. The
gamma-radiation of concrete sample 3 exceeds 6,65 times Dnrn and approximates to the annual doze due to the action of the gamma-radiation of construction materials and emanations of isotopes of radon (350 microSv [2,3]) from the walls.
The average equivalent of doze gamma-radiation for the developed countries constitutes 350 - 411 microSv a year-1. In the considered example the additional gamma-radiation of natural radionucleads constitutes 665,61mcSv a year-1, and for 50 years of life it is 0,015 Sv.
970,6150 : 1000000 = 0,049 Sv
The total irradiation will costitute 0.049 for 50 years for people living in stone houses for 50 years. This value is less than the irradiation doze of the population due to the natural radionuclides and at medical procedures. For comparison: the average irrariation doze of population caused by the natural radiation background and medical procedures, is equaled 0,1-0,2 Sv for 50 years. Thus the part of the somatic long-term effects contribution is 1-2 %. Probability of the general death rate from malignant malignant neoplasms constitutes 14 %.
Conclusions
All this specifies that at the small irradiation dozes there also exists a probability of negative influence on human health. Therefore it is necessary to achieve to use in housing construction of building materials with the least specific activity. The basic danger at the use of the investigated concretes will be connected with the increased gamma-radiation natural radionuclides of building materials. The investigated samples of concrete can be recommended for construction of inhabited premisess, where air exchange is not intensive.
Literature
1. Нормирование радиоактивности строительных
материалов при разном виде их использования / Э.М. Крисюк, В.И. Карпов, П. Кляус и др. // Report SAAS - 250. - Berlin, 1979. - P. 205 - 213.
2. Крисюк Э.М. Радиационный фон помещений. -
М.: Энергоиздат, 1989. - 120 с.
3. Крисюк Э. М. Нормирование радиоактивности
строительных материалов // Г игиена и санитария. - 1980. - №12. - С.32 - 34.
Рецензент: В.К. Жданюк, профессор, д.т.н.,
ХНАДУ.
Статья поступила в редакцию 12 сентября 2006 г.
