Assistant Energy Secretary Jessie Roberson, who headed the environmental cleanup program at the department's nuclear weapons sites, resigned yesterday, citing a desire to spend more time with her family.

Roberson's accelerated agenda for cleaning up weapons sites has been criticized by some state officials and environmentalists as an attempt by the Energy Department to scale back cleanup standards and saddle states with more of the highly radioactive waste.

Her resignation is the third by a senior Energy Department official closely involved in nuclear waste cleanup or environmental management in just over two months. Undersecretary Robert Card, the department's No. 3 official, who was closely involved in nuclear waste issues, and Assistant Secretary Beverly Cook, who reported to Card and was in charge of environmental and health management at nuclear complex sites, resigned in early April after tangling with Congress over a worker health issue.

According to DOE spokesman Joe Davis, Energy Secretary Spencer Abraham told Roberson that, in three years at the job, she had "fundamentally changed the management" of the waste-cleanup effort.

Roberson was appointed to the post after working for the Energy Department office that oversees the cleanup of the Rocky Flats nuclear site in Colorado.