The Himalayan Physics Vol. 6 & 7, April 2017 (92-95) ISSN 2542-2545 A Study of Exposure of Overall Background Radiation In Syangja District of Nepal
S. Timilsina, K. R. Poudel1* P. R. Poudel2 1Department of Physics, Prithvi Narayan Campus, Pokhara, Nepal 2 Department of Physics, Prithvi Narayan Campus, Pokhara, Nepal *Corresponding address: [email protected] Abstract: This study presents general exposure of background radiation to the people living or visiting nine places of Syangja district. A portable GM counter was used to quantify the total radiation at those places. The findings of this study show variation of radiation level at different places. Comparatively large values of radiation counts are observed at high altitude places (Gurung Dada: 70.23 cpm and Pokhari Dada: 64.77 cpm). The value of radiation count inside room is comparatively larger than that at outside room for these places. Moreover, small value of radiation count is observed at river side (Bank of Aandhikhola river: 21.63 cpm). Little large values are observed near Saligram stones and ancient statue than at other regions of one historical/religious place. Hence, results show fluctuations of background radiation level for different places. Some places have comparatively large value of radiation count while some places have comparatively small value. But there is no any abnormal value of radiation counts for all sample places. So there is, generally, no significant risk of public exposure to the background radiation for sample places. Keywords: Background Radiation, CMP 1. Introduction 2. Theory Radiation can be referred as the energy in motion or energy 2.1 Detection and Measurement of Radiation in the form of waves or particles. Radiation is present There are various instruments for detecting and measuring everywhere around us in many forms. The sources of ionizing background radiation level such as Geiger radiation may be of different types such as radiation from Mueller (GM) counter, semiconductor counter, outer space (cosmic rays), radiation from the radioactive environmental radiation monitors etc. Among them the atoms present in earth’s surface, radiation from our own instrument incorporated in this study is GM counter. bodies etc. The dose of radiation varies at different locations. The schematic diagram of this counter is as follows: In accordance with energy, radiations can be classified into two types namely ionizing and non-ionizing radiations. Those types of radiations which have sufficient energy to knock out electrons from the outermost orbit of an atom are known as ionizing radiations. These radiations are also known as high energy radiations or strong radiations. Some examples of ionizing radiations are: alpha radiation, beta radiation, gamma radiation, X-ray etc. Whereas, those types Fig. 1: Schematic Diagram of GM counter of radiations, which lack the sufficient energy required to When ionizing radiation such as an alpha, beta, or gamma knock out electrons from outermost orbit of an atom are particles enters the tube, it can ionize some of the gas known as non-ionizing radiations. These radiations are molecules in the tube. From those ionized atoms, an low energy radiations or weak radiations. Some examples electron is knocked out of the atom and the remaining are microwave radiation, radio wave radiation, infrared atom is positively charged. The high voltage in the tube radiation etc. produces an electric field inside the tube. The electrons that knocked out of the atom are attracted to the positive electrode and the positively charged ions are attracted to the negative electrode. This produces a pulse of current in the 92 A Study of Exposure of Overall Background Radiation In Syangja District of Nepal wires connecting the electrodes and this pulse is counted by 3 Mahendra 34.23 3.48 34.23 ± 3.48 counter. After the pulse is counted, the charged ions become Chowk i.e. (30.75, neutralized and the Geiger Counter is ready to record another 37.71) pulse. For proper use of the Geiger counter, one must have 4 Gurung Dada 70.23 15.97 70.23 ± 15.97 the appropriate voltage across the electrodes. If the voltage i.e. (54.26, 90.2) is too low, the electric field in the tube is too weak to causeBackground radiation counts for different places of Syangja district have been successfully a current pulse. If the voltage is too high, the tube willcollected 5 with theAandhikhola help of GM counter.21.63 Raw data is2.94 in count per21.63 100 sec ± 2.94and is converted into count per minuteBank (cpm). Average values and standard deviationsi.e. of cpm(18.69, for different places undergo continuous discharge, and the tube can be damaged.are calculated by using MS Excel. Those can be tabulated as follows: 24.57) Usually manufacture recommends the correct voltage to use Table 61: RadiationNTC countsOffice of various31.52 places with5.26 standard deviation31.52 ±and 5.26 peak value for the tube. Larger tubes require larger voltages to produce of count/sec i.e. (26.26, the necessary electric fields inside the tube. This is the S.N. Name of the place Mean Count Per Standard Deviation36.38) Mean ± S.D photograph of the GM counter employed in this study. Minute (S.D) 1 7 SyangjaSanyas Hospital 43.9828.59 9.58 2.7743.98 ± 9.58 28.59 ± 2.77 Aashram i.e. (34.4,i.e. (25.82, 31.36) 2 Radio Chowk 30.39 3.29 30.39 ± 3.29 53.56) i.e. (27.1, 33.68) 3 Mahendra Chowk 34.23 3.48 34.23 ± 3.48 8 Pokhari Dada 64.77 9.09 64.77 ± 9.09 i.e. (30.75, 37.71) 4 Gurung Dada 70.23 15.97i.e. (55.68,73.86)70.23 ± 15.97 i.e. (54.26, 90.2) 5 9 AandhikholaDistrict Bank 40.4821.63 6.57 2.9440.48 ± 6.57 21.63 ± 2.94 i.e. (18.69, 24.57) 6 NTCHospital Office 31.52 5.26i.e. (33.91, 31.52 ± 5.26 47.05) i.e. (26.26, 36.38) 7 Sanyas Aashram 43.98 9.58 43.98 ± 9.58 i.e. (34.4, 53.56) 8 ThesePokhari average Dada values of 64.77background radiation9.09 counts for64.77 ± 9.09 i.e. (55.68,73.86) 9 variousDistrict places Hospital are plotted 40.48in a bar diagram by6.57 taking X-axis40.48 ± 6.57 i.e. (33.91, 47.05) as name of the place and Y-axis as average count per minute, These averagewhich isvalues shown of background below: radiation counts for various places are plotted in a bar diagram by taking X-axis as name of the place and Y-axis as average count per minute, Fig. 2: Instruments Used in Radiation Survey (GM tube set) which is shown below: Mean Count Per Minute 3. Result 80 Syangja Hospital 70 Radio Chowk Background radiation counts for different places of Syangja Mahendra Chowk
60 district have been successfully collected with the help of GM Gurung Dada 50 counter. Raw data is in count per 100 sec and is converted Aandhikhola 40 into count per minute (cpm). Average values and standard Nepal Telecom 30 deviations of cpm for different places are calculated by Sanyas Aashram
Mean Count/minute → 20 Pokhari Dada using MS Excel. Those can be tabulated as follows: 10 District Hospital Table 1: Radiation counts of various places with standard 0 deviation and peak value of count/sec Name of Place →
S.N. Name of the Mean Count Standard Mean ± S.D place Per Minute Deviation Fig.3: VariationFig.6.1: Variation of background of background radiation radiation at different at different places places
(S.D) There are no significantly large fluctuations in the arrival 1 Syangja 28.59 2.77 28.59 ± 2.77 of radioactive particles inside GM tube for six places while Hospital i.e. (25.82, moving it at variety of regions of the same place. So counts 31.36) are placed in same category. But for three places there are 2 Radio Chowk 30.39 3.29 30.39 ± 3.29 significant fluctuations in the count rates while moving the i.e. (27.1, device at several parts. So the data are further categorized 33.68) into two or three parts and average values and standard
93 The Himalayan Physics Vol. 6 & 7, April 2017 S. Timilsina, K. R. Poudel and P. R. Poudel deviations of separate parts has also been calculated. Those 68.44 cpm resp.) than at the free environment (46.44 and can be tabulated as follows: 53.76 cpm resp.). So we can have another explanation that Table.2: Variety of Observations at Three Places the high radiation may be due to the presence of little amount S. Places Variety of Regions Mean Standard of radioactive nuclides in house building stones and soil N. Count Deviation because insider radiation level is greater than outsider. Our Per instrument does not tell about the type of radiation present Minute but we can roughly say that the detected radiations are mostly Gurung Inside Room 78.73 7.41 There are no significantly large fluctuations in the arrival of radioactive particles inside GMof gamma type because there was no significant change in Dada tube for 1six places while movingOutside it at variety Room of regions of46.44 the same place.2.99 So counts arecount rates while blocking the window of the tube by thick placed in same category. But for three places there are significant fluctuations in the count rates while moving the device at several parts. So the data are further categorized into two ormaterials. So we can guess that the detected radiation is three parts and Pokhariaverage values Inside and standard Room deviations of68.44 separate parts7.33 has also been enriched with highly penetrative gamma radiation. calculated.2 ThoseDada can be tabulated as follows: Outside Room 53.76 1.73 The minimum value of radiation was observed at the bank Table.6.2: Variety of Observations at Three Places of Aandhikhola river ( i.e. 21.63 cpm). This may be due to S.N. PlacesSanyas VarietyOutside of Regions Temple/ Mean Count32.7 Per Minute 5.9Standard Deviation absence of vegetations and radioisotopes enriched stones and 3 Aashram/ AashramInside Room 78.73 7.41 1 Gurung Dada sand. There may be another reason that low radiation is due Temple NearOutside Shivalinga Room 41.8846.44 3.94 2.99 Inside Room 68.44 7.33 to more absorption of cosmic rays by the dense atmosphere 2 Pokhari Dada Near Saligran Stones 52.67 2.3 Outside Room 53.76 1.73 and Ancient Statue because Aandhikhola river lies at lower height than other Outside Temple/Aashram 32.7 5.9 3 Sanyas places. Near Shivalinga 41.88 3.94 Aashram/Temple The average valuesNear Saligran of background Stones and radiation52.67 counts of three2.3 There is no doubt in saying that high energetic ionizing places (Gurung Dada,Ancient Pokhari Statue Dada and Sanyas Aashram/ radiations are used in hospitals for X-ray technology or
The averageTemple) values forof background variety ofradiation regions counts are of threeplotted places in (Gurung another Dada, bar Pokhari other medical procedures. Several studies had already Dada and Sanyas Aashram/Temple) for variety of regions are plotted in another bar diagram as follows:diagram as follows: been performed to know about the extent of occupational Mean Count Per Minute exposure to the radiations at hospitals. But this study does not focus on occupational exposures rather it focuses on public 80 Gurung Dada Inside Room exposure to background radiation level. Observation have 70 Gurung Dada Outside Room 60 been carried out outside the hospital so as to check whether Pokhari Dada Inside Room 50 the ionizing radiations used in hospitals have higher range to 40 Pokhari Dada Outside Room produce harm to public. By analyzing the observations taken
30 Sanyas Aashram/Temple Outside near Syangja Hospital Pvt. Ltd. And District Hospital (28.59 Temple/Aashram 20 Sanyas Aashram/Temple Near and 40.48 cpm), it can be said that there is no significant Mean Count/minute → Mean Count/minute 10 Shivalinga effect of high energy radiations used in hospitals to the Sanyas Aashram/Temple Near 0 Saligran Stones and Ancient Statue Name of Place with variety of region public because we observed second minimum count near → Syangja Hospital Pvt. Ltd. and little more but not maximum Fig 3: Variation of Radiation at Different Regions of Three Places Fig.6.3: Variation of Radiation at Different Regions of Three Places count at District Hospital; Kumalgaam, Syangja. Conclusion There may be one supposition that signal broadcasting areas Maximum4. Cvaluesonclusion of cpm are obtained at two nearly located villages: Gurung Dada and Pokhari Dada (70.23 and 64.77 cpm respectively). These values are higher than the valueshave high dose of harmful radiation than in other normal obtainedMaximum at other places. values In general of cpm sense are, this obtained may be due at to two the highnearly exposure located to cosmic places. But the observation is opposite to our supposition rays becausevillages: these villagesGurung lie Dadaat high andaltitude Pokhari than other Dada places (70.23 mentioned and above. 64.77 But this explanation may not be fitted here because the background radiation count is maximumbecause background counts observed at signal broadcasting cpm respectively). These values are higher than the values areas (Radio Chowk and NTC office area) are not obtained at other places. In general sense, this may be due to significantly high (30.39 and 31.52 cpm). The main reason the high exposure to cosmic rays because these villages lie behind this may be that the GM counter used in this study just at high altitude than other places mentioned above. But this only counts high energy alpha, beta and gamma radiations explanation may not be fitted here because the background and cannot detect microwaves and radiowaves used in these radiation count is maximum inside the rooms (78.73 and types of signal broadcasting stations as the energy of these
The Himalayan Physics Vol. 6 & 7, April 2017 94 A Study of Exposure of Overall Background Radiation In Syangja District of Nepal kinds of radiation is not enough to produce ionization. Acknowledgements Radiation count for Mahendra Chowk (High residential Author acknowledges P.N Campus Department of Physics area) is comparable (i.e. 34.23 cpm) to signal broadcasting for lab support, K.R Poudel and P.R poudel for support areas. This may be because these places are near and located during this research work. at nearly same height and net contribution of high residents to the background radiation level is negligible. References A little high value of background radiation (as compared 1. Henriksen, T. (2013).Radiation and Health. Oslo, to previous values) has been observed at Shree 1008 Norway: University of Oslo. Champagiri Sanyas Aashram/Temple, Gundhikhola ( 2. Adhikari, P. B., Chhatkuli, D. N. &Koirala, I. P. i.e. overall 43.98 cpm). The overall average value is not (2010).A Textbook of Physics (Volume II, Third significantly different from previous values but this is the Edition).Kathmandu, Nepal: SukundaPustakBhawan average of three different values observed at three regions: Publisher and Distributors. outside Temple/Aashram (32.7 cpm), near Shivalinga (41.88 3. Background radiation Natural Versus Man-Made cpm) and near Saligram stones and ancient statue (52.67 (2002).Washington State of Department of Health. cpm). By observing these values it can be said that the area 4. Giri, K., Giri, D., Murthy, V.K.(2007). Radiation near Shivalinga is more radiated than outer environment and Measurement at X-ray Centres of a Few Hospitals in the area inside the temple containing Saligram stones and Kathmandu City, Nepal (Vol I, No. IV).Dhulikhel, ancient statue is more radiated than outer environment and Kavre, Nepal: Kathmandu University Journal of area containing Shivalinga. Science, Engineering and Technology 5. Recommendation Findings of this or this type of research can be used to confirm and plan strategies related to possible radiation related problems in the particular area. It can also be used to raise public attention and awareness on the subject so as to help in promoting an understanding of the general feature of environment because this type of study helps to know about the quality of environment in terms of radiation dose and to alert about the radiation risk of the specific area. This research may be helpful to make health policies. This research may also be useful to generalize future investigations related to radiation measurement, which may lead to the exploration of new natural sources of radiation.
95 The Himalayan Physics Vol. 6 & 7, April 2017