Second whistleblower Donna Busche fired at troubled Wash. State Hanford nuke plant

A second whistleblower at the troubled Hanford Nuclear Power Reservation in Washington State is out of a job. The facility is owned by the Department of Energy, and it's undergoing a multi-billion-dollar clean-up.

Her employer denies the woman's firing was tied to her ongoing complaints about safety concerns, but as Carter Evans reported on "CBS This Morning," she believes it sends an ominous message.

Asked if she feels like she's a target, Donna Busche said: "Absolutely." 

Until Tuesday, Busche was the manager of Environmental and Nuclear Safety at the Hanford Nuclear Reservation. CBS News interviewed her in October after one of her colleagues was also fired. They had raised concerns about the $13 billion cleanup of a treatment facility in southeastern Washington State.

There are currently 53 million gallons of nuclear waste held in 177 underground tanks. Many have leaked radioactive material into the ground.

In October, Busche said, "We raised technical issues and have received harassment, retaliation. The fact that he was terminated, it sent a resounding message to me, right? And heightened my sense of awareness that I was probably next."

She was next. Late Tuesday, her employer, a Hanford cleanup subcontractor, issued this statement: "Though URS supports Ms. Busche's right to raise concerns and to express her personal views, we do not agree with her assertions that she suffered retaliation or was otherwise treated unfairly. Ms. Busche's employment was terminated...due to issues unrelated to her purported concerns."

CBS News spoke with Busche via Skype. She said, "URS gave me no reason for my termination other than 'unprofessional conduct.' They gave me no documentation. They gave me no explanation."

Her colleague, fellow safety official Walter Tamosaitis, was fired in October. Both he and Busche have been outspoken about dangers at the plant. Among their biggest concerns is a design flaw they claim could lead to a deadly hydrogen explosion or worse -- a nuclear chain reaction.

Busche says their firings will have a chilling effect on anyone else who raises safety concerns at Hanford. She said via Skype, "One of my previous subordinates says that they're actually afraid of getting fired for doing their job."