Probabilistic assessment of the influence of lake properties in long-term radiation doses to humans

Pohjola, Jari; Turunen, Jari; Lipping, Tarmo; Ikonen, A.T.K.

doi:10.1016/j.jenvrad.2016.08.001

Cited by 4 publications

(12 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…influencing the disposal facility (repository) and its surrounding environment necessitating a complex analysis of the processes and their interactions. Thus, the analyzed model output differs from study to study (i.e., peak flux [22], peak time [23], maximum concentration [5], peak dose [24], the amount of radionuclides being released at particular times after repository closure [25], dose over time [26], dose conversion factors [6]). The uncertainty and sensitivity of physical parameters that impact contaminant transport to the environment are considered as a model output to be analyzed (e.g., pressure in the borehole [27]).…”

Section: Radionuclide Transport Model For Rbmk-1500 Snf Disposalmentioning

confidence: 99%

“…Varying the number of input parameters and analyzing the corresponding model results is known as a global sensitivity analysis. It should be mentioned that within the context of geological disposal, the standardized linear regression and correlation analysis are used quite widely [5][6][7][8][9][10][11] for the identification of the most important parameters. Stepwise regression analysis is also used [12,13].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Uncertainty and Sensitivity Analysis at Low Value of Determination Coefficient of Regression Analysis: Case of I-129 Release from RBMK-1500 SNF under Disposal Conditions

2019

View full text Add to dashboard Cite

As in other nuclear countries, the operation of the Ignalina nuclear power plant in Lithuania has led to the accumulation of around 22 thousand assemblies of spent nuclear fuel (SNF). The development of geological disposal program involves an iterative assessment of the system safety supported by scientific research on radionuclides migration and related processes. This study focused on the application of Contribution to the Sample Mean (CSM) and Contribution to Sample Variance (CSV) methods to complement the uncertainty and sensitivity analyses of the time-dependent flux of I-129 from the engineered barriers of a conceptual disposal facility for RBMK-1500 SNF (RBMK is abbreviation of "High Power Channel-type Reactor" (in Russian)). The analysis was performed using a MATLAB platform (8.0.0.783 (R2012b), MathWorks, MA, USA). The mean and variance ratios derived from CSM and CSV plots were applied to estimate the effect of reduced uncertainty range on mean flux and its variance, and the uncertainty analysis was also complimented. Increasing the lower bounding value of defect size enlargement time range to 4.6 × 10 4 years would lead to a lower mean flux until 5 × 10 4 years after repository closure. Later on (up to 1 million years after repository closure), the only reduction of the upper bounding value of the SNF dissolution rate range would affect a decreased mean flux.Keywords: RBMK-1500 spent nuclear fuel; deep geological repository; uncertainty and sensitivity; CSM; CSV; radionuclide migration 3 × 10 −12 (p = 0.15) 1 × 10 −11 (p = 0.7) 3 × 10 −11 (p = 0.15) Discrete 1 Probability density function. SNF: spent nuclear fuel.Minerals 2019, 9, 521 5 of 26 Characterization of Model BehaviorThe model realized using the computer code AMBER [34] assessed time-dependent radionuclide release from the SNF matrix, dissolution, radioactive decay, and contaminant transport by diffusion through engineered barriers. The uncertainty of the main transport-related parameters, including defect size enlargement time, was characterized by probability density function for each parameter. The model output was a large number of the time-dependent flux values over an extended period (10 3 -10 6 years after repository closure), which allowed for the evaluation of the mean flux, the quantiles, and the distribution of the peak flux, as illustrated in Figure 2.

show abstract

Section: Radionuclide Transport Model For Rbmk-1500 Snf Disposalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Uncertainty and Sensitivity Analysis at Low Value of Determination Coefficient of Regression Analysis: Case of I-129 Release from RBMK-1500 SNF under Disposal Conditions

2019

View full text Add to dashboard Cite

show abstract

“…In 18 five sensitivity analysis methods were compared in the context of a compartmental lake-farm biosphere model to study the sensitivity of the dose conversion factors from a spent nuclear fuel repository in bedrock to humans living in the area, to the parameters of the model such as distribution coefficients and concentration ratios between the various compartments. The results are presented in 19 . Both first and total order analyses were made and it was found that the order of the parameter sensitivities was similar for the different methods although the emphasis of the parameters varied.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of neural network metamodels for emulation and sensitivity analysis of radionuclide transport models

Turunen

Lipping

2023

Sci Rep

Self Cite

View full text Add to dashboard Cite

In this paper we compare the outputs of neural network metamodels with numerical solutions of differential equation models in modeling cesium-137 transportation in sand. Convolutional neural networks (CNNs) were trained with differential equation simulation results. Training sets of various sizes (from 5120 to 163,840) were used. First order and total order Sobol methods were applied to both models in order to test the feasibility of neural network metamodels for sensitivity analysis of a radionuclide transport model. Convolutional neural networks were found to be capable of emulating the differential equation models with high accuracy when the training set size was 40,960 or higher. Neural network metamodels also gave similar results compared with the numerical solutions of the partial differential equation model in sensitivity analysis.

show abstract

“…In the model presented in this paper, our earlier lake scenario (Pohjola et al 2016) is altered so that that the radionuclides are transported from groundwater into the lake through the sediments instead of being directly released into the lake water. The agricultural and exposure parts of the model remain the same.…”

Section: Introductionmentioning

confidence: 99%

“…Also, the effects of radionuclide contaminated dust and external irradiation are examined as a complementary view to the earlier work. Sensitivity analysis is improved by adding more simulations to get more reliable estimations of distributions than in Pohjola et al (2016) in which the modelling was based on the abovementioned scenario as well. Two variance-based methods are compared with each other in order to find differences in results and to discuss possible reasons for them.…”

Section: Introductionmentioning

confidence: 99%

Probabilistic assessment of the impact of bottom sediment on doses to humans from a groundwater-mediated radionuclide release in a farm-lake scenario

Pohjola¹,

Turunen²,

Lipping³

et al. 2019

J. Radiol. Prot.

Self Cite

View full text Add to dashboard Cite

Radionuclide transport with groundwater flow and subsequent doses to people are an aspect to be studied when assessing the long-term safety of geological nuclear waste repositories. A scenario where the radionuclide release migrates through a three-layer sediment structure of a lake in a farming environment is presented in this paper. The sediment column consists of deep (till), intermediate (glacio-aquatic sediment) and top layers (clay). The radionuclide release is assumed to enter the deep sediment layer from a bedrock fracture system at a rate of 1 Bq yr−1. The main objectives of the paper are to investigate the most contributing parameters, especially linked to the sediment layers, to the overall dose estimates for humans. The sensitivity analysis was conducted in two phases where the Morris method was used for screening and the Extended Fourier Amplitude Sensitivity Testing and Sobol’s methods were used for estimating total-order indices. The studied radionuclides, 36Cl, 135Cs, 129I, 94Nb, 237Np, 90Sr, 99Tc and 238U, exhibit differences in how the sediment layers affect the concentration in the lake water used for drinking, irrigation and watering cattle and subsequently the dose conversion factors for humans through ingestion, inhalation and external radiation.

show abstract

Probabilistic assessment of the influence of lake properties in long-term radiation doses to humans

Cited by 4 publications

References 16 publications

Uncertainty and Sensitivity Analysis at Low Value of Determination Coefficient of Regression Analysis: Case of I-129 Release from RBMK-1500 SNF under Disposal Conditions

Uncertainty and Sensitivity Analysis at Low Value of Determination Coefficient of Regression Analysis: Case of I-129 Release from RBMK-1500 SNF under Disposal Conditions

Feasibility of neural network metamodels for emulation and sensitivity analysis of radionuclide transport models

Probabilistic assessment of the impact of bottom sediment on doses to humans from a groundwater-mediated radionuclide release in a farm-lake scenario

Contact Info

Product

Resources

About