A nuclear power plant is situated in a valley which can be modeled as a rectangle that is 5 km long, 2 km wide, and 200 m deep. You must evaluate the effects of a scenario where the reactor housing fails and releases radiation into the atmosphere. In the worst-case scenario, 120 kg of Iodine-131 (a radioisotope that causes thyroid gland and liver damage) could be released. a. Assuming the release of Iodine-131 was very rapid and all of it was uniformly distributed through the valley’s atmosphere (with none escaping the valley), what would be the concentration (in ppmv) of Iodine-131 in the valley’s air? Assume a temperature of 20 ˚C and atmospheric pressure of 1.0 atm. b. Assume the Iodine-131 concentration calculated in (a) is the initial concentration in the valley. Now you want to determine how long it will take for the concentration to decrease to the safe limit of 1.0 x 10-5 ppmv. The average wind speed through the valley (entering at one end and exiting at the other) is 1.5 m/min. Iodine-131 is also removed by two other processes: 1) radioactive decay with a half-life of 8.1 days, and 2) sedimentation to the ground with a rate constant of 0.02/d. Draw a picture of the situation, and label the appropriate variables. c. Derive an equation that expresses the concentration of Iodine-131 in the valley’s air as a function of the time since the accident. Use the equation to determine the time (in days) needed for the concentration to decrease to a safe level.