CENE 150L

CENE 150L Introduction to Environmental Engineering Computations (Lab) 1 of 1

Computations Topic Area: Radioactive Waste and Decay

Assign Date: 4/13/15

Due Date (end of class time): 4/20/15

# Problem Description Problem Set No. 7

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A sewage treatment plant discharges an effluent Qe= 0.2 m^3/s into a well mixed lake with a

volume V= 10^4 m^3. The effluent flow is balanced by an equal flow out of the lake. Dissolved

chloroform is formed in the effluent by the reaction between organic carbon in the effluent and

chlorine added to the effluent as a disinfectant. The concentration of dissolved chloroform in the

effluent is measured to be Ce= 1000 mg/L. Once formed, the chloroform degrades with a half life

of 1 day. What is the lifetime cancer risk to a 70-kg person who eats 6.5 g fish from the lake

daily.Bioaccumulation Factor in fish: Lower Level: 6.0003 L/kg; Medium Level: 6.591 L/kg; High

Level: 8.706 L/Kg. Slope Factor can be taken as 0.013 (mg/Kg.d)^-1 [0.013]

Liquid radioactive material with a half life of 3 days is accidentally discharged into a river that has

a constant velocity of 0.1 m/s. As it discharges, the radioactive material (10^5 microCi/ml) mixes

completely and instantly with the river flow. You are responsible for setting the time and distance

downstream over which drinking water withdrawals from the river will be restricted until the

concentration of the radioactive material in the river falls below the water quality standards of

Cmax= 10^-3 microCi/ml. What is your recommendation? [80 days, 690 km]

Use information provided on dependable sources on Internet (by citing the source) calculate the

decay rate constants for radon-222, carbon-14, iodine-125, plutonium-239 and uranium-238.

[varies]