Measurement of Natural Radioactivity and Radon Exhalation Rate in Coal Ash Samples from a Thermal Power Plant (original) (raw)

Measurement of natural radioactivity and radon exhalation rate in fly ash samples from a thermal power plant and estimation of radiation doses

Coal is the main energy source for electricity generation in the world. In Morocco, 37% of electricity generation comes from combustion coal in thermal power plants. This combustion process generates large amounts of fly and bottom ashes. In recent years, these ashes became a great topic of interest because of their different uses and especially in construction materials. In this work, we assess radiation risks due to natural radioactivity in samples of fly and bottom ashes collected from JLEC (Jorf Lasfar Energy Company) thermal power plant, and different analyses are performed through two nuclear techniques such as gamma spectrometry and alpha dosimetry based on the use of LR115 films detectors. Our analysis shows that 226 Ra activities and 232 Th in both ash samples are well above the permissible activity. The values of the external risk index (Hex) and internal one (Hin) for these ashes are below unity, with the exception of 1.28 in fly ash for Hin. The obtained values for the equivalent radium Raeq and annual effective doses Ė in fly and bottom ashes are 324 Bq/kg and 210 Bq/kg, and 0.18 mSv/y and 0.11 mSv/y, respectively. The surface radon exhalation rates for the samples of fly and bottom ashes are 276 mBq•m −2 •h −1 and 381 mBq•m −2 •h −1 , respectively. Based on these results, we have shown that fly ash and bottom one from thermal power plant JLEC didn't have, in any case, a health risk to the public so it can be effectively used in various construction activities.

An investigation of radon exhalation rate and estimation of radiation doses in coal and fly ash samples

Applied Radiation and Isotopes, 2008

Coal is a technologically important material used for power generation. Its cinder (fly ash) is used in the manufacturing of bricks, sheets, cement, land filling etc. Coal and its by-products often contain significant amounts of radionuclides, including uranium which is the ultimate source of the radioactive gas radon. Burning of coal and the subsequent atmospheric emission cause the redistribution of toxic radioactive trace elements in the environment. In the present study, radon exhalation rates in coal and fly ash samples from the thermal power plants at Kolaghat (W.B.) and Kasimpur (U.P.) have been measured using sealed Can technique having LR-115 type II detectors. The activity concentrations of 238 U, 232 Th, and 40 K in the samples of Kolaghat power station are also measured. It is observed that the radon exhalation rate from fly ash samples from Kolaghat is higher than from coal samples and activity concentration of radionuclides in fly ash is enhanced after the combustion of coal. Fly ash samples from Kasimpur show no appreciable change in radon exhalation. Radiation doses from the fly ash samples have been estimated from radon exhalation rate and radionuclide concentrations. r

Radiation Measurements_Measurement of natural radioactivity and radon exhalation rate in fly ash samples from a thermal power plant and estimation of radiation doses

Fly ash produced by coal-burning in thermal power station has become a subject of world wide interest in recent years because of its diverse uses in construction activities and considerable economic and environmental importance. Fly ash is used in the production of bricks, sheets, cement and also in land filling etc. Indian coals used in thermal power plants are found to have high ash contents, resulting in the production of large amount of fly ash. Coal contains radionuclides including uranium (the source of inert gas radon), Th and K. Thus coal combustion results in enhanced concentration of natural radionuclides 226 Ra, 232 Th and 40 K. Since these radionuclides concentration in fly ash plays an important role in health physics it is important to measure radionuclides concentration in fly ash. In the present work enhanced radioactivity and radon exhalation rate from fly ash samples collected from a thermal power plant of NTPC (National Thermal Power Corporation), Dadri (U.P.) India, have been measured.

Analysis of Natural Radioactivity in Coal and Ashes from a Coal Fired Power Plant

Coal is widely used mineral due to its accessibility and abundance in nature. Coal contains naturally occurring radionuclides or Natural Occurring Radioactive Materials (NORM) from Uranium and Thorium series including their decayed daughters namely Uranium-238 (238 U), Radium-226 (226 Ra) and Thorium-232 (232 Th) along with Potassium-40 (40 K). These radionuclides which are a natural phenomenon are released to the environment and concentrated in the ashes resulting from the combustion process. This paper presents an evaluation of the radioactivity content found in the feed coal (FC), bottom ash (BA) and fly ash (FA) sampled from a typical coal fired power plant (CFPP). The samples were measured for activity concentration of several radionuclides namely 238 U, 226 Ra, 232 Th and 40 K by using Instrumental Neutron Activation Analysis (INAA). The radiological hazard based on Radium Equilibrium (Raeq) and External Hazard Index (Hex) was assessed. In this study the activity concentration of all radionuclides in FA was enriched much higher compared to BA and FC. This work found that the degree of enrichment determined by the Enrichment Factor (EF) is differed for bottom and fly ash. The results indicated that each sample have different radiological characteristics. For Raeq and Hex the values calculated for the samples were acceptable and within the limit for construction material. Generally the results proved that the values obtained were much lower and complied with the Malaysia regulatory limit and global values.

Estimation of radon exhalation rate, natural radioactivity and radiation doses in fly ash samples from Durgapur thermal power plant, West Bengal, India

Journal of Environmental Radioactivity, 2008

Coal and its by products often contain significant amounts of radionuclides, including uranium which is the ultimate source of the radioactive gas radon. Burning of coal and the subsequent emission to the atmosphere cause the re-distribution of toxic trace elements in the environment. Due to considerable economic and environmental importance and diverse uses, the collected fly ash has become a subject of worldwide interest in recent years. In the present study, radon exhalation rate and the activity concentration of 238 U, 232 Th and 40 K radionuclides in fly ash samples from Durgapur thermal power plant (WB) have been measured by ''Sealed Can technique'' using LR-115 type II detectors and a low level NaI (Tl) based gamma ray spectrometer, respectively. Radon exhalation rate varied from 360.0 to 470.0 mBq m À2 h À1 with an average value of 406.8 mBq m À2 h À1 . Activity concentrations of 238 U ranged from 84.8 to 126.4 Bq kg À1 with an average value of 99.3 Bq kg À1 , 232 Th ranged from 98.1 to 140.5 Bq kg À1 with an average value of 112.9 Bq kg À1 and 40 K ranged from 267.1 to 364.9 Bq kg À1 with an average value of 308.9 Bq kg À1 . Radium equivalent activity obtained from activity concentrations is found to vary from 256.5 to 352.8 Bq kg À1 with an average value of 282.5 Bq kg À1 . Absorbed gamma dose rates due to the presence of 238 U, 232 Th and 40 K in fly ash samples vary in the range 115.3-158.5 nGy h À1 with an average value of 126.4 nGy h À1 . While the external annual effective dose rate varies from 0.14 to 0.19 mSv y À1 with an average value of 0.15 mSv y À1 , effective dose equivalent estimated from exhalation rate varies from 42.5 to 55.2 mSv y À1 with an average value of 47.8 mSv y À1 . Values of external hazard index H ex for the fly ash samples studied in this work range from 0.69 to 0.96 with a mean value of 0.77.

Measurement of natural radioactivity and radon exhalation rate from rock samples of Jaduguda uranium mines and its radiological implications

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms

Coal is the main energy source for electricity generation in the world. In Morocco, 37% of electricity generation comes from combustion coal in thermal power plants. This combustion process generates large amounts of fly and bottom ashes. In recent years, these ashes became a great topic of interest because of their different uses and especially in construction materials. In this work, we assess radiation risks due to natural radioactivity in samples of fly and bottom ashes collected from JLEC (Jorf Lasfar Energy Company) thermal power plant, and different analyses are performed through two nuclear techniques such as gamma spectrometry and alpha dosimetry based on the use of LR115 films detectors. Our analysis shows that 226 Ra activities and 232 Th in both ash samples are well above the permissible activity. The values of the external risk index (Hex) and internal one (Hin) for these ashes are below unity, with the exception of 1.28 in fly ash for Hin. The obtained values for the equivalent radium Raeq and annual effective doses Ė in fly and bottom ashes are 324 Bq/kg and 210 Bq/kg, and 0.18 mSv/y and 0.11 mSv/y, respectively. The surface radon exhalation rates for the samples of fly and bottom ashes are 276 mBq•m −2 •h −1 and 381 mBq•m −2 •h −1 , respectively. Based on these results, we have shown that fly ash and bottom one from thermal power plant JLEC didn't have, in any case, a health risk to the public so it can be effectively used in various construction activities.

Radon activity and exhalation rates measurements in fly ash from a thermal power plant

Radiation Measurements, 2005

Radon exhalation rate from fly ash samples and from the homogeneous mixture of fly ash of different proportions additive in soil and cement samples to study the effect of the addition was measured by cup dosimeter using SSNTDs. Radon activities were found to vary from (1018 ± 38) to (1435 ± 45) Bq m −3 whereas the radon exhalation rate varied from (366 ± 14) to (516 ± 17) mBq m −2 h −1 . A gradual increase has been observed in samples having fly ash as an additive in cement samples whereas a gradual decrease was observed in soil samples after the addition of fly ash. 238 U in fly ash was measured by a low-level NaI (Tl)-based gamma ray spectrometer. The results show enhancement in U concentration in fly ash as compared to coal samples, whereas radon exhalation rate is less in fly ash samples.

Technical and radiological characterisation of fly ash and bottom ash from thermal power plant

Journal of Radioanalytical and Nuclear Chemistry

Huge quantities of fly ash and bottom ash are generated from thermal power plants and it presents great concern for country, mainly due to the environmental effects. In this study, fly ashes and bottom ash were characterized from technical and radiological aspects. Health effect due to the activity of radionuclides 226Ra, 232Th and 40K was estimated via radium equivalent activity (Raeq), external hazards index (Hex), the external absorbed dose rate (D) and annual effective dose rate (EDR). The specific surface area (40.25 m2 g−1), particle density (1.88 g cm−3) and LOI (23.49%) were typical for bottom ash. Siliceous fly ash contained 32% reactive silica. The annual effective dose rate for all ashes is ≤ 0.2 mSv y−1. Both, fly ash and bottom ash present potential secondary raw materials to be used for building purposes as result of their technological and radiological assessment.

Radon Exhalation and radiological impact of building materials containing fly ASH

2008

The knowledge of the natural radioactivity of building materials is important for the determination of population exposure to radiations, as most of the residents spend about 80% of their time indoors, In controlling the natural radiation exposure for the residents of dwellings, it is necessary to detennine the levels of natllHI1radioactivity and radon exhalation rate from building materials, A knowledge 0[' Hldioactivity present in construction materials helps to (n) assess the possible radiological hazards to human health and (b) develop the standards and guidelines for use and management ofthe,~materials. The pr~s~nt study deals with a total of 71 samples of II dilTerent commonly used structural and covering building materials in which, six types of covering/decorative building materials (marble, granite, mosaic stone, tiles, limestone and lime powder, where, most of them are imported from different countries); four types of structural building materials (cement, brick, sand and stone) and one by-product of coal-fired power plants (fly ash) were collected from varions manufactnrers ami suppliers to measure the natural radioactivity due to the presence of :!:!uRa, 2J2.yhand 4rx.. The measurements were carried ont using gamma-ray spectrometry with an HPGe detector. The radon exhalation rate was measured by hermetically closing the sample in a contain~r and following the radon activity growth as a function of time. The specific activities of the different building materials srudied varied from 46.770101.91 to 117.770106.16 Bq.kg"l, 52.36:102.33 to 157.32"=8.55 Bq.k{l and 668,77="11.50 to 1463.3tli22.77 Bq.kg"1for 22liRa, m'lb and 4~, respectively. The results show that the lowest mean values of the specific activity of 226Ra,232Thand 4~K ar~46.77:101.91 (marble), 52.36:102.33 (marble) and 66~.77"=11.50 Bq.kg,1 (limestone), respectively while the highest mean values of the specific activity of the same radionuclides are 117.77"=6.16, 157.32"=8.55 and 1463.30"=22.77 8q.kg"l, respectively measured in fly ash. The measured activity concentrations for this radionuelide were compared with the reported data of other countries and with the typical world values. The average values of radon exhalution nlte of the studied materials varied li-om 0.010 to 0.044 Bq.kg'l.h'l. This study revealed that all the M f'itil'lltesis

Assessment of the Radiological Impact on the Environment near a Storage Site of Coal Ashes in a Thermal Power Plant

World Journal of Nuclear Science and Technology, 2016

The radiological impact of coal ashes, with enhanced natural radioactivity in the storage site, is due to the presence of naturally occurring radionuclides. Some of these radionuclides have a radioactive period of several million years and will, therefore, have time to migrate to the soil, atmospheric air, surface water, and groundwater. This impact depends mainly on the activity of these coal ashes, the duration of exposure to such waste, transfers to the air, and the leaching phenomenon by rainwater. In this study, and so as to assess the radiological impact of coal ashes of the storage site of the JLEC-Morocco thermal power plant on environment, some analyses are performed by alpha dosimetry and a digital dosimeter on samples of coal ashes, soil, atmospheric air, surface water and groundwater belonging to a perimeter of 10 km around that site. The obtained results show that, within the studied area, the radiological impact on the soil of the coal ashes of the storage site is insignificant even though the concentrations of radon in the near vicinity (1 to 2 km) are moderately important, and remain below 200 Bq/m 3. In the atmospheric air, this impact remains medium for the neighborhoods of the storage site (2 to 3 km) with radon activities superior to 10 Bq/m 3. These results also show that there may be a water contamination of wells located at the storage site without any transfer of radioactivity into the groundwater of the area studied where the concentrations of radon are less than 11.1 Bq/l.