Attorney General Martha Coakley and state Senate President Therese Murray are calling on Congress to address a longstanding problem of what to do with the spent fuel at commercial nuclear power plants.

Coakley and Murray last week sent a letter to members of Congress urging passage of a bill establishing a process for creating permanent storage facilities for spent nuclear fuel.

The lack of such long-term storage means spent fuel must be stored on site, which Murray called a ``major concern.''

Murray's Senate district includes Plymouth, home of the Pilgrim nuclear plant.

The letter warns of potential environmental and public safety issues associated with on-site storage, along with added costs for ratepayers.

Coakley and Murray have previously questioned the Nuclear Regulatory Commission's assertion that the risks of on-site storage are minimal. (Associated Press)