Assume that a decision is made to start ordering reactors at such a constant rate per year from 1990 until 2030, at which time orders will stop, so that all known uranium reserves of 2.3 million metric tons will be used up assume:

a. all plants are identical and need 150 tons of natural uranium per year.
b. it takes 10 years to build a plant
c. every plant has a 30-yr lifetime
d. there are 120 plants operating in 1990 (e) reactors operating in 1990 start retiring in 2000, at a rate of 10/yr. for these reactors, consider their needs only after 1990.

required:
1. calculate how many reactors per year could be ordered and the maximum number of reactors operating at any single time.
2. calculate the maximum number of reactors operating at any single time