Development of a radioecological model for accidental release of radionuclides: Akkuyu and Sinop Nuclear Power Plants
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Date
2014-09
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The Middle East Technical University, Department of Environmental Engineering, The Graduate School of Natural And Applied Sciences
Abstract
Bir nükleer reaktör kazası sonrası atmosfere yayılan salımlar nedeniyle maruz kalınacak radyasyon dozunu ve stokastik riskleri hesaplayan dinamik bir yazılım geliştirilmiştir. Bu model ile farklı radyasyon taşınım yollarından farklı yaş grupları için bireysel dozlar, kolektif dozlar ve stokastik riskler hesaplanabilir. Model belirli zaman aralıklarında hava konsantrasyonları ya da birikim hesaplayabilen herhangi bir uzun dönemli atmosferik taşınım modeli ile birleştirilebilir ya da ölçüm verileri modelde girdi olarak kullanılabilir. Çernobil kazasından sonra çevrede radyonüklit konsantrasyonlarının tespitine ve doz hesaplayan yazılımların kabiliyetlerini değerlendirmeye yönelik çalışmalar oldukça artmıştır. Bu nedenle Çernobil kazası sonrası ölçülen radyoaktivite verileri ile benzer modellerin doğrulama çalışmaları geliştirilen yazılımın doğruluğunu sınamak için kullanılmıştır. Doğrulanmış yazılım sonrasında, Türkiye'de kurulacak Akkuyu ve Sinop nükleer santrallerinde olabilecek ciddi bir kazanın radyolojik sonuçlarını modellemek için kullanılmıştır. Seçilen kaza senaryosu Fukuşhima Daiichi nükleer santral kazasına dayanmaktadır. Geliştirilen yazılım farklı zamanlarda çalıştırılmış ve dozlar üzerinde meteorolojik koşullar kadar bitkilerin vejetasyon döngülerinin de önemli olduğu belirlenmiştir. Akkuyu NGS'de olabilecek ciddi bir kaza senaryosuna göre, ortalama alışkanlıklara sahip yetişkinlerin dozları kazadan 1 yıl sonrasında 3.374 mSv ve ömür boyu ise 9.706 mSv olarak hesaplanmıştır. Sinop NGS'de olabilecek ciddi kazada ise dozlar daha yüksek bulunmuştur. Cs-134, Cs-137 ve I-131 doza en cok katkı yapan izotoplar olarak, tahıllar, inek sütü, tavuk eti, meyveler, koyun eti, dana eti, meyveli ve köklü sebzeler doza en çok katkı yapan gıdalar olarak tanımlanmıştır. Akkuyu nükleer santralinde meydana gelebilecek ciddi bir kaza için en fazla birikimin olduğu grit, en fazla doza katkıda bulunan radyoizotoplar ve gıda maddeleri için LHS metodu ile dozlardaki ve aktivite konsantrasyonlarındaki belirsizlikler hesaplanmıştır. Ayrıca, yukarıda bahsedilen parametreler arasından LHS metodu ile kısa dönem ve yaşam boyu dozlar üzerindeki en çok etkin olan parametreleri ortaya çıkarmaya yönelik korelasyon teknikleri kullanılarak hassasiyet analizleri de yapılmıştır. Yaşam boyu dozların üzerinde Cs'nin toprak-bitki ve inek sütündeki transfer faktörleri, harici radyasyon için azaltım faktörü, dana eti ve tahıl tüketim miktarının oldukça etkili olduğu görülmüştür. Kısa dönemli dozlar üzerinde ise iyodun inek sütündeki transfer faktörü ve çimenin radyonüklitleri tutma katsayısı da etkindir.
A dynamic dose model has been developed to estimate radiation doses and stochastic risks due to atmospheric discharges of radionuclides in the case of a nuclear reactor accident. In addition to individual doses from different pathways for different age groups, collective doses and stochastic risks can be calculated by the model. The model can be coupled to any long-range atmospheric dispersion model which can calculate radionuclide concentrations in air and on the ground at predetermined time intervals or measurement data. Since the Chernobyl accident, there had been an increase in real world data to assess the capabilities of software, which are developed to calculate radionuclide concentrations in the environment and doses to human. Therefore, data related to Chernobyl accident was used to validate the developed software. The validated software was then used to calculate radiological consequences in the case of hypothetical severe accidents at Akkuyu and Sinop NPPs in Turkey. The accident scenario was based on Fukushima Daiichi NPP accident. The newly developed software was run for different release times, and it was turned out that meteorological pattern as well as vegetation cycles of the plants were influencing doses to humans. The doses incurred due to a severe accident at Akkuyu NPP were calculated as 3.374 mSv 1 year after the accident, and the lifetime doses will be 9.706 for adults having average habits; the doses in the case of Sinop NPP accident have been found out to be more than that of Akkuyu NPP accident. Cs-134, Cs-137 and I-131 were identified as the most dose contributing isotopes, and cereals, cow milk, chicken, fruits, lamb, beef, fruit vegetables and root vegetables were the most dose contributing foods respectively. For the maximum deposited grit found out as a result of simulation of Akkuyu NPP accident, and for the related parameters of most dose contributing isotopes and foodstuffs, uncertainty analysis was performed by LHS to predict uncertainties in the doses and activity concentrations. Furthermore, sensitivity analysis was also conducted by again LHS of the aforementioned parameters and the outputs were processed by correlation techniques to find out most influencing parameters on lifetime and short-term doses. It can be concluded that soil-plant transfer factors for Cs have a big influence on the lifetime dose results, feed-animal transfer factor for Cs for cow milk and reduction factors for external radiation, beef and grain consumption amounts have also the high effect on lifetime doses. For the short term doses, cow milk transfer factor for iodine and interception factor for the grass are also influential parameters.
A dynamic dose model has been developed to estimate radiation doses and stochastic risks due to atmospheric discharges of radionuclides in the case of a nuclear reactor accident. In addition to individual doses from different pathways for different age groups, collective doses and stochastic risks can be calculated by the model. The model can be coupled to any long-range atmospheric dispersion model which can calculate radionuclide concentrations in air and on the ground at predetermined time intervals or measurement data. Since the Chernobyl accident, there had been an increase in real world data to assess the capabilities of software, which are developed to calculate radionuclide concentrations in the environment and doses to human. Therefore, data related to Chernobyl accident was used to validate the developed software. The validated software was then used to calculate radiological consequences in the case of hypothetical severe accidents at Akkuyu and Sinop NPPs in Turkey. The accident scenario was based on Fukushima Daiichi NPP accident. The newly developed software was run for different release times, and it was turned out that meteorological pattern as well as vegetation cycles of the plants were influencing doses to humans. The doses incurred due to a severe accident at Akkuyu NPP were calculated as 3.374 mSv 1 year after the accident, and the lifetime doses will be 9.706 for adults having average habits; the doses in the case of Sinop NPP accident have been found out to be more than that of Akkuyu NPP accident. Cs-134, Cs-137 and I-131 were identified as the most dose contributing isotopes, and cereals, cow milk, chicken, fruits, lamb, beef, fruit vegetables and root vegetables were the most dose contributing foods respectively. For the maximum deposited grit found out as a result of simulation of Akkuyu NPP accident, and for the related parameters of most dose contributing isotopes and foodstuffs, uncertainty analysis was performed by LHS to predict uncertainties in the doses and activity concentrations. Furthermore, sensitivity analysis was also conducted by again LHS of the aforementioned parameters and the outputs were processed by correlation techniques to find out most influencing parameters on lifetime and short-term doses. It can be concluded that soil-plant transfer factors for Cs have a big influence on the lifetime dose results, feed-animal transfer factor for Cs for cow milk and reduction factors for external radiation, beef and grain consumption amounts have also the high effect on lifetime doses. For the short term doses, cow milk transfer factor for iodine and interception factor for the grass are also influential parameters.
Description
Keywords
Dynamic software, Dinamik yazılım, Environmental transfer, Çevrede taşınım, Radionuclide, Radyonüklit, Nuclear accident, Nükleer kaza, Chernobyl, Çernobil, Dose, Doz, Uncertainty, Belirsizlik, Sensitivity, Hassasiyet
Citation
Ünver, L. Ö. (2014). Development of a radioecological model for accidental release of radionuclides: Akkuyu and Sinop Nuclear Power Plants. (Yayımlanmamış doktora tezi). Ankara : The Middle East Technical University, The Graduate School of Natural And Applied Sciences.