RESUMO
The problem of indoor radon in high-rise buildings is mostly associated with exhalation from building materials. Characterization of the radon entry from building materials by diffusion is required to provide a proper control of the population indoor radon exposure. To analyze the relationship between the content of Ra-226 in building materials and the indoor radon concentration the results of the following surveys in high-rise buildings in Russian cities were used: 1) indoor radon (>1000 apartments), 2) natural radionuclides in the building materials in existing buildings by means of non-destructive field gamma spectrometry (100 apartments). The surveys were carried out in nine large cities in different climatic zones. The radon entry rate due to diffusion from building materials, D, normalized to Ra-226 activity concentration, Ra, is in the range of 0.2-0.6 (Bq/m3/h)/(Bq/kg), depending on the type of building materials and building construction. In new multi-story buildings, the typical D/Ra ratio can be assumed to be 0.4 (Bq/m3/h)/(Bq/kg). In new energy-efficient buildings, the ratio of the radon concentration to Ra-226 activity concentration is on average 2.1 times higher than in multi-story buildings of lower energy efficiency built before 2000. The average radon exhalation rate from the building materials, normalized to Ra-226 activity concentration, is estimated to be 0.25 Bq/m2/h.
RESUMO
The worldwide trend toward the construction of high-rise buildings with high energy efficiency highlights the role of building materials as a source of indoor radon in the modern urban environment. The aim of the study is to analyze the relationship between the Ra-226 activity concentration in building materials and indoor radon concentration using the example of multi-story buildings in Ekaterinburg. Measurements of the activity concentration of natural radionuclides in building materials were carried out using a new non-destructive method. A radon survey conducted early provided the data on indoor radon concentrations in the same apartments. The obtained Ra-226 activity concentrations in building materials in high-rise buildings were found to be relatively low, ranging from 9.1 to 51 Bq/kg. The typical radon entry rate by diffusion from building materials for modern Russian multi-story buildings can be accepted as equal to 0.5 Bq/(m3âh) per 1 Bq/kg of Ra-226 activity concentration. Ra-226 in building materials has been shown to be a primary source of indoor radon in modern high-rise buildings, where this factor can cause indoor radon concentrations above the reference level of 100 Bq/m3 at low air exchange rates. The activity concentration of Ra-226 in building materials should be considered a separate parameter for regulation within the national radiation protection systems.
Assuntos
Poluentes Radioativos do Ar , Poluição do Ar em Ambientes Fechados , Monitoramento de Radiação , Rádio (Elemento) , Radônio , Radônio/análise , Poluição do Ar em Ambientes Fechados/análise , Monitoramento de Radiação/métodos , Poluentes Radioativos do Ar/análise , Materiais de Construção , Federação Russa , HabitaçãoRESUMO
Otoliths are the organs which fish use for hearing and keeping balance. Otoliths are the most calcified tissues in the fish body. In contrast to bones, otoliths are not affected by remodeling and, therefore, they are expected to accumulate any dose from ionizing radiation during lifetime. Therefore, EPR dosimetry with fish otoliths could be an important tool for dose reconstruction in radiobiology and radioecology. It could also provide useful information remediation actions to de-contaminate waterbodies. Consequently, in the present study, otoliths of three contaminated fish species (roach (Rutilus rutilus), pike (Esox lucius) and perch (Perca Fluviatilis)) were examined with Electron Paramagnetic Resonance (EPR) spectroscopy. The fish were caught at storage reservoirs of liquid radioactive waste from Mayak PA and from the upper reach of the Techa River, which have been contaminated with different levels of radionuclide activity concentrations. It is shown that the radiation-induced EPR signal of otolith is stable and characterized by a linear dose response. However, the slope of the calibration curve (corresponding to the radiation sensitivity of the material) is not the same for different species; this may be caused by differences in mineralization. The reconstructed doses were found to be in the range from undetectable (in fish from the upper stream of the Techa River) up to 265 Gy (in roach from the most contaminated waterbody). In parallel, otoliths were measured with ß-counter to detect 90Sr/90Y. Samples were also tested on the presence of alpha-emitters, but no alpha activity above background could be detected. However, a significant activity concentration of 90Sr was detected (from 1 × 101 to 2 × 104 Bq/g). The EPR doses measured correlated with the 90Sr activity concentration measured in the otolith samples.
Assuntos
Espectroscopia de Ressonância de Spin Eletrônica , Membrana dos Otólitos/efeitos da radiação , Radiometria/métodosRESUMO
The objective of the study was comparison of the doses received due to contamination of the Techa River with those received from the indoor radon exposure. The study was performed on the example of Muslyumovo, the village closest to Mayak nuclear complex. The accidental doses were estimated using data on radionuclide intakes and ICRP-72 dose coefficients, and Techa River Dosimetry System. Radon exposure was estimated applying results of the radon surveys in 1992 and 2015. The doses prevented by means of different protection measures were considered. The maximum reduction of population exposure could be achieved in the case of timely evacuation to uncontaminated territory together with the indoor radon prevention measures.
Assuntos
Poluentes Radioativos do Ar/análise , Reatores Nucleares , Monitoramento de Radiação/métodos , Liberação Nociva de Radioativos , Resíduos Radioativos/análise , Radônio/análise , Rios , Poluentes Radioativos da Água/análise , Humanos , Doses de Radiação , Federação RussaRESUMO
Since 1995, requirements on energy-efficient building construction were established in Russian Building Codes. In the course of time, utilisation of such technologies became prevailing, especially in multi-storey building construction. According to the results of radon survey in buildings constructed meeting new requirements on energy efficiency, radon concentration exceeds the average level in early-constructed buildings. Preponderance of the diffusion mechanism of radon entry in modern multi-storey buildings has been experimentally established. The experimental technique of the assessment of ventilation rate in dwellings under real conditions was developed. Based on estimates of average ventilation rate, it was approved that measures to increase energy efficiency lead to reduction in ventilation rate and accumulation of higher radon concentrations indoors. Obtained ventilation rate values have to be considered as extremely low.
Assuntos
Movimentos do Ar , Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Radiação de Fundo , Algoritmos , Arquitetura de Instituições de Saúde/normas , Arquitetura de Instituições de Saúde/tendências , Habitação/normas , Habitação/tendências , Exposição à Radiação , Monitoramento de Radiação/métodos , Radônio/análise , Federação Russa , VentilaçãoRESUMO
Modern energy-efficient architectural solutions and building construction technologies such as monolithic concrete structures in combination with effective insulation reduce air permeability of building envelope. As a result, air exchange rate is significantly reduced and conditions for increased radon accumulation in indoor air are created. Based on radon survey in Ekaterinburg, Russia, remarkable increase in indoor radon concentration level in energy-efficient multi-storey buildings was found in comparison with similar buildings constructed before the-energy-saving era. To investigate the problem of indoor radon in energy-efficient multi-storey buildings, the measurements of radon concentration have been performed in seven modern buildings using radon monitoring method. Values of air exchange rate and other parameters of indoor climate in energy-efficient buildings have been estimated.
Assuntos
Poluição do Ar em Ambientes Fechados/análise , Arquitetura de Instituições de Saúde , Habitação , Monitoramento de Radiação , Poluentes Radioativos/análise , Radônio/análise , Poluição do Ar em Ambientes Fechados/prevenção & controle , Humanos , Proteção Radiológica , Poluentes Radioativos/efeitos adversos , Radônio/efeitos adversos , VentilaçãoRESUMO
To investigate the influence of modern building construction technologies on the accumulation of radon indoor, 20 rooms in buildings constructed using mostly monolithic concrete or aerated concrete blocks have been studied. Dominance of the diffusion mechanism of radon entry in buildings constructed with modern technologies has been established. As a result of computer simulations it was found that the main contribution to the variability of radon concentration was made by changes in the ventilation rate. At a low ventilation rate (<0.2 h(-1)) radon concentration above 200 Bq m(-3) can be observed for residential buildings. There is a need for the regulation of the radium-specific activity in building materials. According to the estimates of this study, the content of 226Ra in building materials should not exceed the value of 100 Bq kg(-1).
Assuntos
Poluição do Ar em Ambientes Fechados/análise , Materiais de Construção/análise , Arquitetura de Instituições de Saúde , Habitação , Monitoramento de Radiação , Poluentes Radioativos/análise , Radônio/análise , Poluição do Ar em Ambientes Fechados/prevenção & controle , Simulação por Computador , Humanos , Proteção Radiológica , Poluentes Radioativos/efeitos adversos , Radônio/efeitos adversos , VentilaçãoRESUMO
The contemporary radiation doses to the organs and tissues of murine rodents inhabiting the most contaminated part of the EURT were estimated. The bones of animals trapped in 2005 at territories with a surface (90)Sr contamination of 24-40 MBq/m(2) were used for dose reconstruction. The concentration of (90)Sr in the animals' skulls was measured using the nondestructive method of bone radiometry. The dose estimation procedure included application of the published values of absorbed fractions of beta-radiation energy for different combinations of source and target organs, accounting for the distribution of radionuclide by organs and tissues. Twelve conversion coefficients were obtained to link the skeleton (90)Sr concentration and doses to eleven organs and the whole body. The whole-body dose rate on the 45th day after the beginning of exposure normalised to whole-body activity is 0.015 (mGy day(-1))/(Bq g(-1)). The estimation yields the following values of doses for Microtus agrestis, Sylvaemus uralensis and Clethrionomys rutilus, respectively: maximum absorbed doses in the skeleton: 267, 121 and 160 mGy; mean whole body internal doses: 37, 14 and 23 mGy; mean internal dose rates on the last day before trapping: 1.2; 0.44 and 0.75 mGy/day. Approaches to the assessment of doses to foetuses and to offspring before weaning were also developed.
Assuntos
Arvicolinae , Osso e Ossos/química , Murinae , Radioisótopos de Estrôncio/análise , Animais , Feminino , Masculino , Modelos Teóricos , Doses de Radiação , Monitoramento de RadiaçãoRESUMO
There are practically no direct techniques for measuring radon entry rate in the rooms. The suggested technique allows estimating such parameter under real conditions. The technique for radon diagnostic procedures including radon entry rate and air change rate assessment was proposed and tested in the field under various experimental conditions. The method consists of the continuous measurement of radon concentration, temperature and pressure difference between indoor and outdoor atmosphere. It was demonstrated that the study of dependence of radon entry rate on temperature difference ΔT between indoor and outdoor atmosphere allows to estimate the dominant radon entry mechanism - diffusion mechanism (absence of the dependence on ΔT) or convective (radon entry rate increase at ΔT increase). It was shown that simultaneous measurements of time series of radon concentration and pressure difference between building envelope and outdoor atmosphere allow assessing such room parameter as Effective Leakage Area. The approach applied in this paper to estimate the air change rate practically is not differing from tracer gas techniques when the constant gas entry rate is used. It was shown that radon could be used as kind of tracer gas to estimate the air change rate. Obtained measurement results for all buildings confirmed the seasonal variations of radon concentrations. A correlation of radon concentration and air change rate with outside temperature occurred in general.