In 1979, an accident happened at the Three Mile Island nuclear power plant in Pennsylvania. Through a combination of mechanical failure and human error, cooling water drained from the reactor ves-sel, temperatures rose inside the reactor core, and metal surrounding the uranium fuel rods began to melt, releasing radiation. This partial meltdown proceeded through half of one reactor core. Area residents stood ready to be evacuated. For-tunately, however, most radiation remained trapped inside the building that contained the nuclear reac-tor. The accident was brought under control within days. The damaged reactor was shut down. It took years, and about a billion dollars, to clean up the damage.

16. Which of the following best describes the sequence of events at Three Mile Island?a. partial meltdown, followed by loss of cooling water, followed by rising temperatures in the reactor coreb. partial meltdown, followed by the release of radiation, followed by an explosionc. partial meltdown, followed by cleanup, fol-lowed by rising temperatures in the reactor cored. loss of cooling water, followed by rising temperatures in the reactor core, followed by partial meltdown

17. People were not evacuated becausea. the cleanup had begun. b. most of the radiation did not leak out. c. the evacuation would have cost billions of dollars. d. only one reactor was affected.

18. Which of the following was NOT involved in the accident at Three Mile Island?a. an explosionb. reactor damagec. nuclear fissiond. mistakes by people