Unexpected gas releases from Hanford tank
[link to www.nwcn.com]

[snip]

Confidential sources say it began on March 16 and lasted for several days, much longer than usual, and they worry a single spark could have set off an explosive release of radioactivity.

This comes two days after a report by a government panel expressing concerns about the release of flammable gasses at Hanford and the government's inability to respond to them.

Workers who toil above the buried Hanford tank farms constantly monitor the tanks for gas build-ups and will conduct controlled releases to reduce pressure. We're told this was a spontaenous release, not controlled.