IDAHO FALLS, Idaho (AP) A cleanup contractor is preparing to demolish a 1960s-era nuclear reactor west of Idaho Falls.

Work to remove the Experimental Breeder Reactor-II began in the spring, when contractors successfully entombed most of the reactor vessel in concrete, The Post Register reported. CWI is looking to remove the reactor’s dome by the end of next September.

“It’s kind of a landmark,” said Troy Donahue, the CWI director for the program, of the old reactor. “But [the property is] earmarked for other things they want to build to make a world-class lab.”

EBR-II began operating in 1964 at what was then Argonne National Laboratory-West and is now known as Idaho National Laboratory’s Materials and Fuels Complex, about 30 miles west of Idaho Falls.

The sodium-cooled reactor was used for research and testing new fuels and materials. Before it shut down in 1994, the reactor produced as many as 20 megawatts of power.

CWI has been working to decommission the reactor and related facilities since 2009.

Donahue said the next step is to demolish a massive crane that was built inside the done, which can be seen from U.S. Highway 20. In May or April, the dome itself will come down.

For some, the disappearing dome is bittersweet. Former EBR-II worker Sharon Laird said she would be disappointed to see it go.

“You would come over the hill and start down and you saw that beautiful dome in the distance to the right,” Laird said. “It symbolized something.”