The Dreamliner recently got the green light to fly again by the Federal Aviation Administration, which had grounded the new aircraft for three months after its batteries caught fire in two separate incidents, The Guardian reported Wednesday.
Addressing the National Transportation Safety Board, Martin Robinett, Boeing's manager of regulatory administration, said there was a "one-in-10-million" chance of a "major or more severe" failure.
He calculated the possibility of the batteries having a "catastrophic" failure at one in a billion.
The lithium-ion batteries have been linked to fires in smaller airplanes, cars, laptops and mobile devices.
Jerry Hulm, the company's safety engineer, said the batteries had undergone vigorous testing for more than 10,000 hours.
The cause of the battery fires is still unknown, but Hulm said engineers had been able to reproduce the failure without knowing the root cause.
Boeing has now placed a new casing around the battery and created a system to vent away gases.
While Boeing is sticking with the lithium-ion technology, The Daily Beast reported Thursday that other aircraft manufacturers looked into the new batteries, then backed away, choosing to go with nickel-cadmium batteries, which are considered less risky.
Airbus actually chose to go with lithium-ion batteries, then pulled back when it took note of problems Boeing was having with the new system.
Bombardier in Canada and Mitsubishi Regional Jet also looked at the lithium-ion option, but said no.
"We looked into the technology and decided that lithium-ion batteries were not ready, not stable enough, to be used on our airplane," Bombardier spokesman Marc Duchesne said.
As reported in The New York Times, Mitsubishi President Teruaki Kawai said the new batteries were "too dangerous."