DHS plans to spend $300 million on troubled radiation detectors -

The Department of Homeland Security plans to spend more than $300 million over the next four years on radiation-detection equipment that has not been fully tested and may not work, according to a budget request and an unreleased report by the Government Accountability Office.

The department’s plan is the latest in a series of efforts involving the troubled Advanced Spectroscopic Portal machine, which was touted by the George W. Bush administration as an advanced way to prevent the importation of radioactive materials that could be used in a nuclear or dirty bomb.