تعیین غلظت، تغییرات فصلی و مدت زمان ماندگاری ذرات پرتوزای طبیعی در هوای تهران

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد مهندسی پدافند غیرعامل(گرایش مدیریت بحران) دانشگاه جامع امام حسین(ع)

2 دانشیار مرکز علم و فناوری پدافند غیرعامل، دانشکده و پژوهشکده پدافند غیرعامل، دانشگاه جامع امام حسین(ع)

3 استادیار مرکز راهبردی آب، انرژی و محیط‌زیست، دانشکده و پژوهشکده عمران، آب و انرژی، دانشگاه جامع امام حسین(ع)

چکیده

یکی از مهم‌ترین چالش‌های حوادث هسته‌ای میزان انتشار و تعلیق ذرات پرتوزا در اتمسفر است. اطلاع از رفتار این ذرات در جو مدیریت و تصمیمات بعدی از اتفاقات پیش‌بینی‌نشده را بهینه‌تر خواهد کرد. استفاده از ذرات پرتوزای طبیعی به‌عنوان ردیاب­های محیطی برای مطالعه آلاینده­های اتمسفری یکی از مطالعات کلیدی و مهم در انجام تحقیقات اتمسفری است. برای بررسی تعیین غلظت رادیونوکلئیدهای سرب 210، بیسموت 210 و پلونیم 210 و همچنین تخمین زمان اقامت برای کل ذرات معلق پرتوزا به‌صورت ماهانه از آبان ماه 1400 الی مهرماه 1401 در شهر تهران نمونه‌برداری صورت گرفت. نمونه‌ها توسط پمپ نمونه‌بردار حجم بالا با دبی متوسط 5/1 مترمکعب در دقیقه با بازه زمانی 6 تا 12 ساعت انجام و در سازمان انرژی اتمی آماده‌سازی و شمارش شدند. نتایج میانگین ماهیانه غلظت رادیونوکلئیدها نشان می‌دهد که بیشترین مقدار اندازه‌گیری شده برای سرب 210 در مهرماه با mBq/m3 25/1 بود. متوسط غلظت سالیانه برای این پارامتر در حدود mBq/m3 89/0 بود که کمترین مقدار آن در فروردین­ماه با مقدار mBq/m3 42/0 ثبت شد. نتایج نشان از افزایش نسبی در غلظت این متغیر برای فروردین‌ و اردیبهشت­ماه و کاهش نسبی برای شهریور و دی­ماه بود. میانگین غلظت اندازه­گیری شده برای متغیر پلونیم 210 در کل دوره حدود   mBq/m305۸/0 بود. همچنین  mBq/m3095/0 در آذر‌ماه به‌عنوان بیشترین غلظت و mBq/m3 032/0 در دی­ماه به‌عنوان کمترین مقدار اندازه­گیری شده برای این رادیونوکلئید است. همین روند برای بیسموت 210 نیز با میانگین کلی mBq/m3 42/0 برای دوره بررسی مشاهده شد. بیشترین و کمترین مقدار اندازه­گیری شده برای این رادیونوکلئید در کل دوره بررسی به ترتیب 85/0 و 18/0 mBq/m3 بود. طبق نتایج به‌دست‌آمده بر مبنای سرب 210/ پلونیم 210 میانگین زمان اقامت ذرات معلق 1/20 روز تخمین زده شد. بر این اساس تیرماه با میانگین 5/22 روز و دی‌ماه 8/17 روز به­عنوان بیشترین و کمترین زمان اقامت اندازه‌گیری شده در این کار پژوهشی تخمین زده شد. نتایج به‌دست‌آمده می‌تواند در تدوین سناریوهای انتشار و استنشاق ذرات پرتوزای ناشی از حوادث هسته‌ای کمک نماید.

کلیدواژه‌ها


عنوان مقاله [English]

Determining the Concentration, Seasonal Changes and Shelf Life of Natural Radioactive Particles in the Air of Tehran

نویسندگان [English]

  • Shahab Ghorbani 1
  • Ali Saeidi 2
  • Balal Oroji 3
1 Passive Defense Science and Technology Center, Faculty and Research Institute of Passive Defense, , Imam Hossein Comprehensive University
2 Passive Defense Science and Technology Center, Faculty and Research Institute of Passive Defense, , Imam Hossein Comprehensive University
3 Water, Energy and Environment Center, Faculty and Research Institute of Civil Engineering, Water and Energy, Imam Hossein Comprehensive University
چکیده [English]

One of the most important challenges of nuclear accidents is the release and suspension of radioactive particles in the atmosphere. Knowing the behavior of these particles in the atmosphere will optimize management and subsequent decisions of unforeseen events. Using natural radioactive particles as environmental tracers to study atmospheric pollutants is one of the key and important studies in conducting atmospheric research. In order to determine the concentration of Pb-210, Bi-210 and Po-210 radionuclides, as well as to estimate the residence time of radioactive particles, sampling was done on a monthly basis from November 1400 to October 1401 in Tehran. The samples were taken by a high volume sampling pump with an average flow rate of 1.5 cubic meters per minute with a time interval of 6 to 12 hours and were prepared and counted in the Atomic Energy Organization. The results of the monthly average concentration of radionuclides show that the highest measured value for Pb-210 was 1.25 mBq/m3 in October. The average annual concentration for this parameter was around 0.89 mBq/m3, and its lowest value was recorded in April with a value of 0.42 mBq/m3. The results showed a relative increase in the concentration of this variable for April and May and a relative decrease for September and December. The average measured concentration for the variable  Po-210 in the whole period was about 0.058 mBq/m3. Also, 0.095 mBq/m3 in December is the highest concentration and 0.032 mBq/m3 in January is the lowest value measured for this radionuclide. The same trend was observed for Bi-210 with an overall average of 0.42 mBq/m3 for the period under review. The highest and lowest values measured for this radionuclide in the entire study period were 0.85 and 0.18 mBq/m3, respectively. According to the obtained results, based on Pb-210/Po-210, the average residence time of suspended particles was estimated to be 20.1 days. Based on this, July with an average of 22.5 days and January with an average of 17.8 days were estimated as the maximum and minimum length of stay measured in this research work. The obtained results can help in formulating the release and inhalation scenarios of radioactive particles caused by nuclear accidents.

کلیدواژه‌ها [English]

  • Radioactive Particulate Matter
  • Atmospheric Residence Time
  • Particle Activity
  • Concentration
  • Tehran Air

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