A possible method of low-level radioactive waste disposal in shallow water-table regions is burial in the...

 

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A possible method of low-level radioactive waste disposal in shallow water-table regions is burial in the less permeable strata of aquifer-aquitard systems. Shown below is such a hydrogeological situation where wastes have been placed approximately 30 m below the top of a 50 m thick aquitard. The aquitard itself is a layered structure comprised of ten homogeneous strata each 5 m thick. From the top to the bottom, the hydraulic conductivity values (in m/s) of the layers are 3* 10-10, 2 10-10, 7 * 10-¹1, 1 * 10-9, 5 * 10-10, 6* 10-11, 3 * 10-10, 4*10-10, 5*10-¹⁰, 6* 10-10. The effective porosity of the aquitard material is 15%. 50m J₁ 10m AQUITARD Piezometric surface of confined aquifer unconfined aquifer 30m CONFINED RAD WASTE AQUIFER Groundwater development of the unconfined formation will result in a 10 m lowering of the hydraulic head with respect to the lower confined aquifer. Thus there will be a net upward flow through the aquitard and there is a possibility that the unconfined aquifer will be contaminated by dissolved radioactive material. 1) Find the hydraulic head difference between the radioactive waste and the top of aquitard. 2) How many years will it take for the radioactive material to travel through the aquitard? 3) The radionuclides buried at this site have radioactive half-lives generally less than 100 years. If the travel time is longer than 20 times of radioactive half-life, the environmental hazard is deemed as low. Does this particular disposal site pose significant environmental hazard? A possible method of low-level radioactive waste disposal in shallow water-table regions is burial in the less permeable strata of aquifer-aquitard systems. Shown below is such a hydrogeological situation where wastes have been placed approximately 30 m below the top of a 50 m thick aquitard. The aquitard itself is a layered structure comprised of ten homogeneous strata each 5 m thick. From the top to the bottom, the hydraulic conductivity values (in m/s) of the layers are 3* 10-10, 2 10-10, 7 * 10-¹1, 1 * 10-9, 5 * 10-10, 6* 10-11, 3 * 10-10, 4*10-10, 5*10-¹⁰, 6* 10-10. The effective porosity of the aquitard material is 15%. 50m J₁ 10m AQUITARD Piezometric surface of confined aquifer unconfined aquifer 30m CONFINED RAD WASTE AQUIFER Groundwater development of the unconfined formation will result in a 10 m lowering of the hydraulic head with respect to the lower confined aquifer. Thus there will be a net upward flow through the aquitard and there is a possibility that the unconfined aquifer will be contaminated by dissolved radioactive material. 1) Find the hydraulic head difference between the radioactive waste and the top of aquitard. 2) How many years will it take for the radioactive material to travel through the aquitard? 3) The radionuclides buried at this site have radioactive half-lives generally less than 100 years. If the travel time is longer than 20 times of radioactive half-life, the environmental hazard is deemed as low. Does this particular disposal site pose significant environmental hazard?

Answer rating: 100% (QA)

Solution The correct answer is Option D which is 139800 Budget... View the full answer