DAUPHIN COUNTY, Pa. (WHTM) — A big step forward at Three Mile Island has been 30 years in the making.

The project to decommission Unit 2, which suffered a partial meltdown in 1979, is now moving into a new phase, allowing crews to begin removing core debris.

Unit 2 had been in a monitoring phase for just shy of three decades. The company that owns Unit 2 says it will take about six years to remove the damaged remnants of the core and then another seven or eight years to completely dismantle the structure.

Unit 1 is also on track for decommissioning, which is expected to be done by 2079.