3D simulation of radionuclide transport in porous media

Mazen Saad
in collaboration with Fabien  Marpeau

We present an efficient and easily implementable finite volume method simulating radionuclide transport through highly heterogeneous grounds in three space dimensions. The numerical concentration of the transported chemicals are proved to remain nonegative and stable.
Then, we run a realistic test case in which some radioactive iodine I^{129} particles are released from a leak in an underground nuclear waste disposal site. The question of whether the radionuclide invades the undreground and reach the ground surface is investigated.

For more information  HERE.


Transport equation : We propose an efficient  limited second order scheme, stable and positive.  


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Mesh (65x 47 x 50 elements, left) and initial condition (right) for the spiral velocity advection test case.


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Spiral velocity advection test: numerical solution computed with the limited scheme at times t=0.25, t=0.5 and t=0.75.

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From left to right, numerical solution computed with the limited scheme, Murman scheme, and exact solution at time t=1.


APPLICATION: THE 3D COUPLEX TEST-CASE

The goal of this test is to simulate the underground displacement of radioactive Iodine (I 129) coming from a leak in a nuclear waste repository which lies in a clay layer. This clay layer is surrounded by two limestone layers (from Oxfordian and Dogger era), while a Marl layer represents the near ground on the top of the domain.


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Domain for the 3D couplex test (right),  front face of the domain (centre) and Mesh for the 3D Couplex benchmark: 236250 elements.

velocity
Velocity (m/year)  8.11x10^{-10} <=  |V| <= 0.022.



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