FirstEnergy began loading fuel into the reactor at the Davis-Besse nuclear plant Wednesday -- a milestone in the company's efforts to get the facility ready for restart.

The loading of 177 fuel bundles, each weighing about 1,500 pounds, will take about four days, said FirstEnergy spokesman Richard Wilkins.

The company said it needs to load the fuel to run tests to make sure coolant isn't leaking from underneath the reactor. If no leaks are found, the fuel will not be removed, Wilkins said.

Tests will also begin shortly to make sure that the large concrete building that surrounds the reactor, called the containment vessel, doesn't leak, either, he said. The containment vessel is the last safety barrier between the reactor and the environment.