This month, it's buying its first cascading oxygen system--similar to what firefighters use--to give miners an uninterrupted supply of air while trying to escape. Alpha expects to eventually spend at least $10 million on that technology.

It's also hired a company to develop wireless sensors that can check for methane in a mine, Goodwin said. They will be in place in every Alpha mine by next year.

The investments come even as Alpha loses money. Last month, it posted a first-quarter loss of $29.1 million due to weak demand for coal and rising costs.

Alpha also says it implemented plans to ensure coal dust accumulations are properly treated and has a system for monitoring results.

But problems remain.

Earlier this month, MSHA issued citations and enforcement orders at Alpha's Road Fork No. 1 in Wyoming County, where a conveyor belt caught fire.

Inspectors found inoperable smoke detectors and fire suppression systems, and accumulations of coal dust as deep as 18 inches. MSHA said managers charged with safety inspections failed to report or record obvious safety hazards, or fix those they did list.

The conditions were similar to those in another Massey disaster. In January 2006, two West Virginia miners died in a fire at Aracoma Coal Co.'s Alma No. 1 mine.

Goodwin and Ruby said they're monitoring the Road Fork investigation.

"We don't mean to paint that everything's coming up roses," Goodwin said. "They still have room to improve."

But he said that after lengthy conversations with Alpha leadership, he's confident of its corporate resolve to change Massey's ways.

It's noteworthy, Ruby added, that after the settlement, "there was a wholesale house cleaning of the executive ranks of Massey.

"That factors into our thinking about the tone at the top," he said.

Ruby declined to detail how deep that process went, saying it's among the information Alpha considers commercially sensitive.

Goodwin said the settlement had three objectives--addressing systemic problems at Massey, advancing state-of-the-art technology and making clear "that shortchanging mine safety is bad business."

Progress so far, he said, "shows the chance we took entering a resolution of this nature was a good chance to take."

Alpha Natural Resources has significantly cut its accident and injury rates in the six months since a landmark $210 million settlement that spared the company criminal charges over the 2010 mine explosion that killed 29 workers, federal prosecutors said.

Alpha cut its accident rate by a third and its injury rate by 25 percent at West Virginia's Upper Big Branch mine and other former Massey Energy Co. operations. It's also broken ground on an $18 million training center that U.S. Attorney Booth Goodwin said will dramatically benefit the industry. When it opens in Julian next June, miners will be able to train for dangerous conditions in a 96,000-square-foot simulation laboratory.

Goodwin said the progress report he and lead prosecutor Steven Ruby received shows Virginia-based Alpha making "pretty substantial progress" as it tries to overhaul the Massey Energy mines it acquired last summer and fix a corporate culture that devalued safety.

"This is like turning a freight liner," Goodwin said. "This is a company that now has 11,000 coal miners, and they can't just turn on a dime. But they got pretty close."

In April 2010, an explosion fueled by methane and coal dust killed 29 men in the southern West Virginia mine. It was the worst U.S. coal mining disaster in 40 years, and it led to the retirement of former chief executive Don Blankenship and criminal charges against a former superintendent and security chief.

Ruby said his criminal investigation remains active.

Four reports on the disaster agree on its mechanics: Massey allowed methane and coal dust to accumulate, and worn and broken cutting equipment created the spark that ignited the fuel. Broken and clogged water sprayers allowed a mere flare-up to turn into an inferno that ripped through miles of underground tunnels.

The federal Mine Safety and Health Administration said the root cause was Massey's "systematic, intentional and aggressive efforts" to conceal life-threatening problems, noting managers even maintained two sets of pre-shift inspection books--an accurate one for itself, and a fake one for regulators.

They also habitually warned miners underground when an inspector arrived on site, trying to give crews time to make the mine appear safe.

Training to stop those practices is among the many components of the non-prosecution agreement Goodwin's office reached with Alpha in December. It wiped the slate clean of some 370 safety violations related to Upper Big Branch and required Alpha to pay $35 million in fines for violations there and at other Massey mines.

Those fines were paid, and in a five-page letter to prosecutors, Alpha says it's making progress on other required initiatives. Alpha asked prosecutors to refrain from making its full report public, citing concerns about competitive information.

Alpha says it has, among other things:

-done remedial maintenance at all Massey mines and added safety personnel at some;

-purchased digital sensors that can continuously monitor air flow and methane levels;

-created a foundation that will spend $48 million on research and development in mine safety and health;

-and hired a new regulatory compliance director.

This month, it's buying its first cascading oxygen system--similar to what firefighters use--to give miners an uninterrupted supply of air while trying to escape. Alpha expects to eventually spend at least $10 million on that technology.

It's also hired a company to develop wireless sensors that can check for methane in a mine, Goodwin said. They will be in place in every Alpha mine by next year.

The investments come even as Alpha loses money. Last month, it posted a first-quarter loss of $29.1 million due to weak demand for coal and rising costs.

Alpha also says it implemented plans to ensure coal dust accumulations are properly treated and has a system for monitoring results.

But problems remain.

Earlier this month, MSHA issued citations and enforcement orders at Alpha's Road Fork No. 1 in Wyoming County, where a conveyor belt caught fire.

Inspectors found inoperable smoke detectors and fire suppression systems, and accumulations of coal dust as deep as 18 inches. MSHA said managers charged with safety inspections failed to report or record obvious safety hazards, or fix those they did list.

The conditions were similar to those in another Massey disaster. In January 2006, two West Virginia miners died in a fire at Aracoma Coal Co.'s Alma No. 1 mine.

Goodwin and Ruby said they're monitoring the Road Fork investigation.

"We don't mean to paint that everything's coming up roses," Goodwin said. "They still have room to improve."

But he said that after lengthy conversations with Alpha leadership, he's confident of its corporate resolve to change Massey's ways.

It's noteworthy, Ruby added, that after the settlement, "there was a wholesale house cleaning of the executive ranks of Massey.

"That factors into our thinking about the tone at the top," he said.

Ruby declined to detail how deep that process went, saying it's among the information Alpha considers commercially sensitive.

Goodwin said the settlement had three objectives--addressing systemic problems at Massey, advancing state-of-the-art technology and making clear "that shortchanging mine safety is bad business."

Progress so far, he said, "shows the chance we took entering a resolution of this nature was a good chance to take."