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Federal prosecutors say Alpha Natural Resources has slashed its accident and injury rates in the six months since a landmark settlement spared the company criminal charges in West Virginia's Upper Big Branch mine disaster.

It's also started construction of an $18 million training center that U.S. Attorney Booth Goodwin tells The Associated Press will dramatically benefit the industry. When it opens next June, miners will be able to train for dangerous conditions in a 96,000-square-foot simulation lab.

Goodwin says Virginia-based Alpha has room to improve. But he says it's making "substantial progress" as it overhauls the Massey Energy mines it acquired last summer and fixes a corporate culture that devalued safety.

The 2010 explosion in southern West Virginia killed 29 men and was the worst U.S. mining disaster in 40 years.