Question

A plant along the river accidentally spilled 5 × 10⁵ Bq of ¹³⁷Cs into the river. Average river width, depth, and velocity are 40 m, 5 m, and 3 m s^?1, respectively. The longitudinal dispersion coefficient of the river is estimated to be 200 m² s^?1. A nearby city uses the river for drinking water and has its water intake station 5 km downstream from the plant. Assuming that ¹³⁷Cs will be fully mixed across the river cross section by the time it reaches the city intake station and that radionuclide decay is negligible,

What will the ¹³⁷Cs concentration be at the intake station 30 min after the accidental spill?

What will the ¹³⁷Cs concentration be and at what time will it occur when the center of ¹³⁷Cs plume patch arrives at the city intake station?

Answer 1